Bio

Clinical Focus


  • Vascular Medicine
  • Cardiovascular Disease

Academic Appointments


Publications

All Publications


  • Clinical and Genetic Determinants of Varicose Veins Prospective, Community-Based Study of approximate to 500 000 Individuals CIRCULATION Fukaya, E., Flores, A. M., Lindholm, D., Gustafsson, S., Zanetti, D., Ingelsson, E., Leeper, N. J. 2018; 138 (25): 2869–80
  • Proefferocytic Therapy Promotes Transforming Growth Factor-beta Signaling and Prevents Aneurysm Formation CIRCULATION Kojima, Y., Werner, N., Ye, J., Nanda, V., Tsao, N., Wang, Y., Flores, A. M., Miller, C. L., Weissman, I., Deng, H., Xu, B., Dalman, R. L., Eken, S. M., Pelisek, J., Li, Y., Maegdefessel, L., Leeper, N. J. 2018; 137 (7): 750–53

    View details for PubMedID 29440201

    View details for PubMedCentralID PMC5819616

  • The Role of Efferocytosis in Atherosclerosis CIRCULATION Kojima, Y., Weissman, I. L., Leeper, N. J. 2017; 135 (5): 476-489

    Abstract

    The necrotic core has long been a hallmark of the vulnerable atherosclerotic plaque. Although apoptotic cells are cleared quickly in almost all other tissue beds, their removal appears to be significantly impaired in the diseased blood vessel. Emerging evidence indicates that this phenomenon is caused by a defect in efferocytosis, the process by which apoptotic tissue is recognized for engulfment by phagocytic cells such as macrophages. Genetic and experimental data suggest that efferocytosis is impaired during atherogenesis caused by dysregulation of so-called eat me ligands, which govern the edibility of cells undergoing programmed cell death. The following is a summary of recent data indicating that efferocytosis is a major unappreciated driver of lesion expansion but also a reversible defect that can potentially be targeted as a means to prevent plaque progression.

    View details for DOI 10.1161/CIRCULATIONAHA.116.025684

    View details for Web of Science ID 000393716200009

    View details for PubMedID 28137963

    View details for PubMedCentralID PMC5302553

  • Canagliflozin and Cardiovascular and Renal Events in Type 2 Diabetes. The New England journal of medicine Neal, B., Perkovic, V., Mahaffey, K. W., de Zeeuw, D., Fulcher, G., Erondu, N., Shaw, W., Law, G., Desai, M., Matthews, D. R. 2017; 377 (7): 644–57

    Abstract

    Background Canagliflozin is a sodium-glucose cotransporter 2 inhibitor that reduces glycemia as well as blood pressure, body weight, and albuminuria in people with diabetes. We report the effects of treatment with canagliflozin on cardiovascular, renal, and safety outcomes. Methods The CANVAS Program integrated data from two trials involving a total of 10,142 participants with type 2 diabetes and high cardiovascular risk. Participants in each trial were randomly assigned to receive canagliflozin or placebo and were followed for a mean of 188.2 weeks. The primary outcome was a composite of death from cardiovascular causes, nonfatal myocardial infarction, or nonfatal stroke. Results The mean age of the participants was 63.3 years, 35.8% were women, the mean duration of diabetes was 13.5 years, and 65.6% had a history of cardiovascular disease. The rate of the primary outcome was lower with canagliflozin than with placebo (occurring in 26.9 vs. 31.5 participants per 1000 patient-years; hazard ratio, 0.86; 95% confidence interval [CI], 0.75 to 0.97; P<0.001 for noninferiority; P=0.02 for superiority). Although on the basis of the prespecified hypothesis testing sequence the renal outcomes are not viewed as statistically significant, the results showed a possible benefit of canagliflozin with respect to the progression of albuminuria (hazard ratio, 0.73; 95% CI, 0.67 to 0.79) and the composite outcome of a sustained 40% reduction in the estimated glomerular filtration rate, the need for renal-replacement therapy, or death from renal causes (hazard ratio, 0.60; 95% CI, 0.47 to 0.77). Adverse reactions were consistent with the previously reported risks associated with canagliflozin except for an increased risk of amputation (6.3 vs. 3.4 participants per 1000 patient-years; hazard ratio, 1.97; 95% CI, 1.41 to 2.75); amputations were primarily at the level of the toe or metatarsal. Conclusions In two trials involving patients with type 2 diabetes and an elevated risk of cardiovascular disease, patients treated with canagliflozin had a lower risk of cardiovascular events than those who received placebo but a greater risk of amputation, primarily at the level of the toe or metatarsal. (Funded by Janssen Research and Development; CANVAS and CANVAS-R ClinicalTrials.gov numbers, NCT01032629 and NCT01989754 , respectively.).

    View details for PubMedID 28605608

  • CD47-blocking antibodies restore phagocytosis and prevent atherosclerosis. Nature Kojima, Y., Volkmer, J., McKenna, K., Civelek, M., Lusis, A. J., Miller, C. L., DiRenzo, D., Nanda, V., Ye, J., Connolly, A. J., Schadt, E. E., Quertermous, T., Betancur, P., Maegdefessel, L., Matic, L. P., Hedin, U., Weissman, I. L., Leeper, N. J. 2016; 536 (7614): 86-90

    Abstract

    Atherosclerosis is the disease process that underlies heart attack and stroke. Advanced lesions at risk of rupture are characterized by the pathological accumulation of diseased vascular cells and apoptotic cellular debris. Why these cells are not cleared remains unknown. Here we show that atherogenesis is associated with upregulation of CD47, a key anti-phagocytic molecule that is known to render malignant cells resistant to programmed cell removal, or 'efferocytosis'. We find that administration of CD47-blocking antibodies reverses this defect in efferocytosis, normalizes the clearance of diseased vascular tissue, and ameliorates atherosclerosis in multiple mouse models. Mechanistic studies implicate the pro-atherosclerotic factor TNF-α as a fundamental driver of impaired programmed cell removal, explaining why this process is compromised in vascular disease. Similar to recent observations in cancer, impaired efferocytosis appears to play a pathogenic role in cardiovascular disease, but is not a fixed defect and may represent a novel therapeutic target.

    View details for PubMedID 27437576

  • CDKN2B Regulates TGFß Signaling and Smooth Muscle Cell Investment of Hypoxic Neovessels. Circulation research Nanda, V., Downing, K. P., Ye, J., Xiao, S., Kojima, Y., Spin, J. M., DiRenzo, D., Nead, K. T., Connolly, A. J., Dandona, S., Perisic, L., Hedin, U., Maegdefessel, L., Dalman, J., Guo, L., Zhao, X., Kolodgie, F. D., Virmani, R., Davis, H. R., Leeper, N. J. 2016; 118 (2): 230-240

    Abstract

    Genetic variation at the chromosome 9p21 cardiovascular risk locus has been associated with peripheral artery disease, but its mechanism remains unknown.To determine whether this association is secondary to an increase in atherosclerosis, or it is the result of a separate angiogenesis-related mechanism.Quantitative evaluation of human vascular samples revealed that carriers of the 9p21 risk allele possess a significantly higher burden of immature intraplaque microvessels than carriers of the ancestral allele, irrespective of lesion size or patient comorbidity. To determine whether aberrant angiogenesis also occurs under nonatherosclerotic conditions, we performed femoral artery ligation surgery in mice lacking the 9p21 candidate gene, Cdkn2b. These animals developed advanced hindlimb ischemia and digital autoamputation, secondary to a defect in the capacity of the Cdkn2b-deficient smooth muscle cell to support the developing neovessel. Microarray studies identified impaired transforming growth factor β (TGFβ) signaling in cultured cyclin-dependent kinase inhibitor 2B (CDKN2B)-deficient cells, as well as TGFβ1 upregulation in the vasculature of 9p21 risk allele carriers. Molecular signaling studies indicated that loss of CDKN2B impairs the expression of the inhibitory factor, SMAD-7, which promotes downstream TGFβ activation. Ultimately, this manifests in the upregulation of a poorly studied effector molecule, TGFβ1-induced-1, which is a TGFβ-rheostat known to have antagonistic effects on the endothelial cell and smooth muscle cell. Dual knockdown studies confirmed the reversibility of the proposed mechanism, in vitro.These results suggest that loss of CDKN2B may not only promote cardiovascular disease through the development of atherosclerosis but may also impair TGFβ signaling and hypoxic neovessel maturation.

    View details for DOI 10.1161/CIRCRESAHA.115.307906

    View details for PubMedID 26596284

    View details for PubMedCentralID PMC4740238

  • The Genetic Basis of Peripheral Arterial Disease Current Knowledge, Challenges, and Future Directions CIRCULATION RESEARCH Kullo, I. J., Leeper, N. J. 2015; 116 (9): 1551-1560

    Abstract

    Several risk factors for atherosclerotic peripheral arterial disease (PAD), such as dyslipidemia, diabetes mellitus, and hypertension, are heritable. However, predisposition to PAD may be influenced by genetic variants acting independently of these risk factors. Identification of such genetic variants will provide insights into underlying pathophysiologic mechanisms and facilitate the development of novel diagnostic and therapeutic approaches. In contrast to coronary heart disease, relatively few genetic variants that influence susceptibility to PAD have been discovered. This may be, in part, because of greater clinical and genetic heterogeneity in PAD. In this review, we (1) provide an update on the current state of knowledge about the genetic basis of PAD, including results of family studies and candidate gene, linkage as well as genome-wide association studies; (2) highlight the challenges in investigating the genetic basis of PAD and possible strategies to overcome these challenges; and (3) discuss the potential of genome sequencing, RNA sequencing, differential gene expression, epigenetic profiling, and systems biology in increasing our understanding of the molecular genetics of PAD.

    View details for DOI 10.1161/CIRCRESAHA.116.303518

    View details for Web of Science ID 000353383600005

    View details for PubMedID 25908728

    View details for PubMedCentralID PMC4410432

  • Proton Pump Inhibitor Usage and the Risk of Myocardial Infarction in the General Population. PloS one Shah, N. H., LePendu, P., Bauer-Mehren, A., Ghebremariam, Y. T., Iyer, S. V., Marcus, J., Nead, K. T., Cooke, J. P., Leeper, N. J. 2015; 10 (6)

    Abstract

    Proton pump inhibitors (PPIs) have been associated with adverse clinical outcomes amongst clopidogrel users after an acute coronary syndrome. Recent pre-clinical results suggest that this risk might extend to subjects without any prior history of cardiovascular disease. We explore this potential risk in the general population via data-mining approaches.Using a novel approach for mining clinical data for pharmacovigilance, we queried over 16 million clinical documents on 2.9 million individuals to examine whether PPI usage was associated with cardiovascular risk in the general population.In multiple data sources, we found gastroesophageal reflux disease (GERD) patients exposed to PPIs to have a 1.16 fold increased association (95% CI 1.09-1.24) with myocardial infarction (MI). Survival analysis in a prospective cohort found a two-fold (HR = 2.00; 95% CI 1.07-3.78; P = 0.031) increase in association with cardiovascular mortality. We found that this association exists regardless of clopidogrel use. We also found that H2 blockers, an alternate treatment for GERD, were not associated with increased cardiovascular risk; had they been in place, such pharmacovigilance algorithms could have flagged this risk as early as the year 2000.Consistent with our pre-clinical findings that PPIs may adversely impact vascular function, our data-mining study supports the association of PPI exposure with risk for MI in the general population. These data provide an example of how a combination of experimental studies and data-mining approaches can be applied to prioritize drug safety signals for further investigation.

    View details for DOI 10.1371/journal.pone.0124653

    View details for PubMedID 26061035

    View details for PubMedCentralID PMC4462578

  • Oxido-reductive regulation of vascular remodeling by receptor tyrosine kinase ROS1 JOURNAL OF CLINICAL INVESTIGATION Ali, Z. A., Perez, V. D., Yuan, K., Orcholski, M., Pan, S., Qi, W., Chopra, G., Adams, C., Kojima, Y., Leeper, N. J., Qu, X., Zaleta-Rivera, K., Kato, K., Yamada, Y., Oguri, M., Kuchinsky, A., Hazen, S. L., Jukema, J. W., Ganesh, S. K., Nabe, E. G., Channon, K., Leon, M. B., Charest, A., Quertermous, T., Ashley, E. A. 2014; 124 (12): 5159-5174

    Abstract

    Angioplasty and stenting is the primary treatment for flow-limiting atherosclerosis; however, this strategy is limited by pathological vascular remodeling. Using a systems approach, we identified a role for the network hub gene glutathione peroxidase-1 (GPX1) in pathological remodeling following human blood vessel stenting. Constitutive deletion of Gpx1 in atherosclerotic mice recapitulated this phenotype of increased vascular smooth muscle cell (VSMC) proliferation and plaque formation. In an independent patient cohort, gene variant pair analysis identified an interaction of GPX1 with the orphan protooncogene receptor tyrosine kinase ROS1. A meta-analysis of the only genome-wide association studies of human neointima-induced in-stent stenosis confirmed the association of the ROS1 variant with pathological remodeling. Decreased GPX1 expression in atherosclerotic mice led to reductive stress via a time-dependent increase in glutathione, corresponding to phosphorylation of the ROS1 kinase activation site Y2274. Loss of GPX1 function was associated with both oxidative and reductive stress, the latter driving ROS1 activity via s-glutathiolation of critical residues of the ROS1 tyrosine phosphatase SHP-2. ROS1 inhibition with crizotinib and deglutathiolation of SHP-2 abolished GPX1-mediated increases in VSMC proliferation while leaving endothelialization intact. Our results indicate that GPX1-dependent alterations in oxido-reductive stress promote ROS1 activation and mediate vascular remodeling.

    View details for DOI 10.1172/JCI77484

    View details for Web of Science ID 000345677200011

    View details for PubMedID 25401476

  • Cyclin-dependent kinase inhibitor 2B regulates efferocytosis and atherosclerosis JOURNAL OF CLINICAL INVESTIGATION Kojima, Y., Downing, K., Kundu, R., Miller, C., Dewey, F., Lancero, H., Raaz, U., Perisic, L., Hedin, U., Schadt, E., Maegdefessel, L., Quertermous, T., Leeper, N. J. 2014; 124 (3): 1083-1097

    Abstract

    Genetic variation at the chromosome 9p21 risk locus promotes cardiovascular disease; however, it is unclear how or which proteins encoded at this locus contribute to disease. We have previously demonstrated that loss of one candidate gene at this locus, cyclin-dependent kinase inhibitor 2B (Cdkn2b), in mice promotes vascular SMC apoptosis and aneurysm progression. Here, we investigated the role of Cdnk2b in atherogenesis and found that in a mouse model of atherosclerosis, deletion of Cdnk2b promoted advanced development of atherosclerotic plaques composed of large necrotic cores. Furthermore, human carriers of the 9p21 risk allele had reduced expression of CDKN2B in atherosclerotic plaques, which was associated with impaired expression of calreticulin, a ligand required for activation of engulfment receptors on phagocytic cells. As a result of decreased calreticulin, CDKN2B-deficient apoptotic bodies were resistant to efferocytosis and not efficiently cleared by neighboring macrophages. These uncleared SMCs elicited a series of proatherogenic juxtacrine responses associated with increased foam cell formation and inflammatory cytokine elaboration. The addition of exogenous calreticulin reversed defects associated with loss of Cdkn2b and normalized engulfment of Cdkn2b-deficient cells. Together, these data suggest that loss of CDKN2B promotes atherosclerosis by increasing the size and complexity of the lipid-laden necrotic core through impaired efferocytosis.

    View details for DOI 10.1172/JCI70391

    View details for Web of Science ID 000332347700028

    View details for PubMedID 24531546

  • Transcriptional activation of hypoxia-inducible factor-1 (HIF-1) in myeloid cells promotes angiogenesis through VEGF and S100A8 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ahn, G., Seita, J., Hong, B., Kim, Y., Bok, S., Lee, C., Kim, K. S., Lee, J. C., Leeper, N. J., Cooke, J. P., Kim, H. J., Kim, I. H., Weissman, I. L., Brown, J. M. 2014; 111 (7): 2698-2703

    Abstract

    Emerging evidence indicates that myeloid cells are essential for promoting new blood vessel formation by secreting various angiogenic factors. Given that hypoxia-inducible factor (HIF) is a critical regulator for angiogenesis, we questioned whether HIF in myeloid cells also plays a role in promoting angiogenesis. To address this question, we generated a unique strain of myeloid-specific knockout mice targeting HIF pathways using human S100A8 as a myeloid-specific promoter. We observed that mutant mice where HIF-1 is transcriptionally activated in myeloid cells (by deletion of the von Hippel-Lindau gene) resulted in erythema, enhanced neovascularization in matrigel plugs, and increased production of vascular endothelial growth factor (VEGF) in the bone marrow, all of which were completely abrogated by either genetic or pharmacological inactivation of HIF-1. We further found that monocytes were the major effector producing VEGF and S100A8 proteins driving neovascularization in matrigel. Moreover, by using a mouse model of hindlimb ischemia we observed significantly improved blood flow in mice intramuscularly injected with HIF-1-activated monocytes. This study therefore demonstrates that HIF-1 activation in myeloid cells promotes angiogenesis through VEGF and S100A8 and that this may become an attractive therapeutic strategy to treat diseases with vascular defects.

    View details for DOI 10.1073/pnas.1320243111

    View details for Web of Science ID 000331396500062

    View details for PubMedID 24497508

    View details for PubMedCentralID PMC3932909

  • Alternative Ankle-Brachial Index Method Identifies Additional At-Risk Individuals JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Nead, K. T., Cooke, J. P., Olin, J. W., Leeper, N. J. 2013; 62 (6): 553-559

    Abstract

    OBJECTIVES: To determine whether utilization of an alternative ankle-brachial index (ABI) calculation method improves mortality risk prediction compared to traditional methods. BACKGROUND: The ABI is used to diagnose peripheral arterial disease (PAD), and to identify those at risk for cardiovascular events. Traditionally, the ABI is calculated using the higher of the dorsalis pedis and posterior tibial ankle arteries. Studies directly comparing calculation methods are limited. METHODS: The ABI was calculated at baseline in 1,413 study participants undergoing non-emergent coronary angiography subsequently followed for all-cause and cardiovascular mortality. There were 224 individuals assigned to the traditional-PAD group (ABI < 0.90) using the traditional ABI method. Of those remaining, an alternative ABI method utilizing the lower of the two ankle pressures assigned 282 patients to the alternative-PAD group. The 862 individuals not assigned to PAD by either method were the no-PAD group. RESULTS: There were 163 mortalities during a median follow-up of 5.0 years. Adjusted Cox regression models showed that the alternative-PAD group had an increased risk for all-cause (HR=1.49; 95% CI, 1.01-2.19) and cardiovascular mortality (HR=3.21; 95% CI, 1.53-6.37) versus the no-PAD group. Additionally, in the no-PAD group, there was an 11% (HR=1.11; 95% CI, 1.05-1.17) increased risk of all-cause mortality per 1mm Hg increased difference between the left and right brachial systolic pressures. CONCLUSION: The implementation of an alternative ABI method and use of the brachial difference identifies individuals at an increased risk for mortality who are currently missed using traditional ABI methods. Current ABI protocols may need to be evaluated.

    View details for DOI 10.1016/j.jacc.2013.04.061

    View details for Web of Science ID 000322524300011

    View details for PubMedID 23707317

  • Loss of CDKN2B promotes p53-dependent smooth muscle cell apoptosis and aneurysm formation. Arteriosclerosis, thrombosis, and vascular biology Leeper, N. J., Raiesdana, A., Kojima, Y., Kundu, R. K., Cheng, H., Maegdefessel, L., Toh, R., Ahn, G., Ali, Z. A., Anderson, D. R., Miller, C. L., Roberts, S. C., Spin, J. M., de Almeida, P. E., Wu, J. C., Xu, B., Cheng, K., Quertermous, M., Kundu, S., Kortekaas, K. E., Berzin, E., Downing, K. P., Dalman, R. L., Tsao, P. S., Schadt, E. E., Owens, G. K., Quertermous, T. 2013; 33 (1): e1-e10

    Abstract

    Genomewide association studies have implicated allelic variation at 9p21.3 in multiple forms of vascular disease, including atherosclerotic coronary heart disease and abdominal aortic aneurysm. As for other genes at 9p21.3, human expression quantitative trait locus studies have associated expression of the tumor suppressor gene CDKN2B with the risk haplotype, but its potential role in vascular pathobiology remains unclear.Here we used vascular injury models and found that Cdkn2b knockout mice displayed the expected increase in proliferation after injury, but developed reduced neointimal lesions and larger aortic aneurysms. In situ and in vitro studies suggested that these effects were attributable to increased smooth muscle cell apoptosis. Adoptive bone marrow transplant studies confirmed that the observed effects of Cdkn2b were mediated through intrinsic vascular cells and were not dependent on bone marrow-derived inflammatory cells. Mechanistic studies suggested that the observed increase in apoptosis was attributable to a reduction in MDM2 and an increase in p53 signaling, possibly due in part to compensation by other genes at the 9p21.3 locus. Dual inhibition of both Cdkn2b and p53 led to a reversal of the vascular phenotype in each model.These results suggest that reduced CDKN2B expression and increased smooth muscle cell apoptosis may be one mechanism underlying the 9p21.3 association with aneurysmal disease.

    View details for DOI 10.1161/ATVBAHA.112.300399

    View details for PubMedID 23162013

  • Genetics of Peripheral Artery Disease CIRCULATION Leeper, N. J., Kullo, I. J., Cooke, J. P. 2012; 125 (25): 3220-3228
  • MicroRNA-21 Blocks Abdominal Aortic Aneurysm Development and Nicotine-Augmented Expansion SCIENCE TRANSLATIONAL MEDICINE Maegdefessel, L., Azuma, J., Toh, R., Deng, A., Merk, D. R., Raiesdana, A., Leeper, N. J., Raaz, U., Schoelmerich, A. M., McConnell, M. V., Dalman, R. L., Spin, J. M., Tsao, P. S. 2012; 4 (122)

    Abstract

    Identification and treatment of abdominal aortic aneurysm (AAA) remains among the most prominent challenges in vascular medicine. MicroRNAs are crucial regulators of cardiovascular pathology and represent possible targets for the inhibition of AAA expansion. We identified microRNA-21 (miR-21) as a key modulator of proliferation and apoptosis of vascular wall smooth muscle cells during development of AAA in two established murine models. In both models (AAA induced by porcine pancreatic elastase or infusion of angiotensin II), miR-21 expression increased as AAA developed. Lentiviral overexpression of miR-21 induced cell proliferation and decreased apoptosis in the aortic wall, with protective effects on aneurysm expansion. miR-21 overexpression substantially decreased expression of the phosphatase and tensin homolog (PTEN) protein, leading to increased phosphorylation and activation of AKT, a component of a pro-proliferative and antiapoptotic pathway. Systemic injection of a locked nucleic acid-modified antagomir targeting miR-21 diminished the pro-proliferative impact of down-regulated PTEN, leading to a marked increase in the size of AAA. Similar results were seen in mice with AAA augmented by nicotine and in human aortic tissue samples from patients undergoing surgical repair of AAA (with more pronounced effects observed in smokers). Modulation of miR-21 expression shows potential as a new therapeutic option to limit AAA expansion and vascular disease progression.

    View details for DOI 10.1126/scitranslmed.3003441

    View details for PubMedID 22357537

  • Inhibition of microRNA-29b reduces murine abdominal aortic aneurysm development JOURNAL OF CLINICAL INVESTIGATION Maegdefessel, L., Azuma, J., Toh, R., Merk, D. R., Deng, A., Chin, J. T., Raaz, U., Schoelmerich, A. M., Raiesdana, A., Leeper, N. J., McConnell, M. V., Dalman, R. L., Spin, J. M., Tsao, P. S. 2012; 122 (2): 497-506

    Abstract

    MicroRNAs (miRs) regulate gene expression at the posttranscriptional level and play crucial roles in vascular integrity. As such, they may have a role in modifying abdominal aortic aneurysm (AAA) expansion, the pathophysiological mechanisms of which remain incompletely explored. Here, we investigate the role of miRs in 2 murine models of experimental AAA: the porcine pancreatic elastase (PPE) infusion model in C57BL/6 mice and the AngII infusion model in Apoe-/- mice. AAA development was accompanied by decreased aortic expression of miR-29b, along with increased expression of known miR-29b targets, Col1a1, Col3a1, Col5a1, and Eln, in both models. In vivo administration of locked nucleic acid anti-miR-29b greatly increased collagen expression, leading to an early fibrotic response in the abdominal aortic wall and resulting in a significant reduction in AAA progression over time in both models. In contrast, overexpression of miR-29b using a lentiviral vector led to augmented AAA expansion and significant increase of aortic rupture rate. Cell culture studies identified aortic fibroblasts as the likely vascular cell type mediating the profibrotic effects of miR-29b modulation. A similar pattern of reduced miR-29b expression and increased target gene expression was observed in human AAA tissue samples compared with that in organ donor controls. These data suggest that therapeutic manipulation of miR-29b and its target genes holds promise for limiting AAA disease progression and protecting from rupture.

    View details for DOI 10.1172/JCI61598

    View details for PubMedID 22269326

  • MicroRNA-26a Is a Novel Regulator of Vascular Smooth Muscle Cell Function JOURNAL OF CELLULAR PHYSIOLOGY Leeper, N. J., Raiesdana, A., Kojima, Y., Chun, H. J., Azuma, J., Maegdefessel, L., Kundu, R. K., Quertermous, T., Tsao, P. S., Spin, J. M. 2011; 226 (4): 1035-1043

    Abstract

    Aberrant smooth muscle cell (SMC) plasticity has been implicated in a variety of vascular disorders including atherosclerosis, restenosis, and abdominal aortic aneurysm (AAA) formation. While the pathways governing this process remain unclear, epigenetic regulation by specific microRNAs (miRNAs) has been demonstrated in SMCs. We hypothesized that additional miRNAs might play an important role in determining vascular SMC phenotype. Microarray analysis of miRNAs was performed on human aortic SMCs undergoing phenotypic switching in response to serum withdrawal, and identified 31 significantly regulated entities. We chose the highly conserved candidate miRNA-26a for additional studies. Inhibition of miRNA-26a accelerated SMC differentiation, and also promoted apoptosis, while inhibiting proliferation and migration. Overexpression of miRNA-26a blunted differentiation. As a potential mechanism, we investigated whether miRNA-26a influences TGF-β-pathway signaling. Dual-luciferase reporter assays demonstrated enhanced SMAD signaling with miRNA-26a inhibition, and the opposite effect with miRNA-26a overexpression in transfected human cells. Furthermore, inhibition of miRNA-26a increased gene expression of SMAD-1 and SMAD-4, while overexpression inhibited SMAD-1. MicroRNA-26a was also found to be downregulated in two mouse models of AAA formation (2.5- to 3.8-fold decrease, P < 0.02) in which enhanced switching from contractile to synthetic phenotype occurs. In summary, miRNA-26a promotes vascular SMC proliferation while inhibiting cellular differentiation and apoptosis, and alters TGF-β pathway signaling. MicroRNA-26a represents an important new regulator of SMC biology and a potential therapeutic target in AAA disease.

    View details for DOI 10.1002/jcp.22422

    View details for Web of Science ID 000287258800019

    View details for PubMedID 20857419

    View details for PubMedCentralID PMC3108574

  • MicroRNA and Mechanisms of Impaired Angiogenesis in Diabetes Mellitus CIRCULATION Leeper, N. J., Cooke, J. P. 2011; 123 (3): 236-238
  • Stem Cell Therapy for Vascular Regeneration Adult, Embryonic, and Induced Pluripotent Stem Cells CIRCULATION Leeper, N. J., Hunter, A. L., Cooke, J. P. 2010; 122 (5): 517-526
  • Apelin prevents aortic aneurysm formation by inhibiting macrophage inflammation AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Leeper, N. J., Tedesco, M. M., Kojima, Y., Schultz, G. M., Kundu, R. K., Ashley, E. A., Tsao, P. S., Dalman, R. L., Quertermous, T. 2009; 296 (5): H1329-H1335

    Abstract

    Apelin is a potent inodilator with recently described antiatherogenic properties. We hypothesized that apelin might also attenuate abdominal aortic aneurysm (AAA) formation by limiting disease-related vascular wall inflammation. C57BL/6 mice implanted with osmotic pumps filled with apelin or saline were treated with pancreatic elastase to create infrarenal AAAs. Mice were euthanized for aortic PCR analysis or followed ultrasonographically and then euthanized for histological analysis. The cellular expression of inflammatory cytokines and chemokines in response to apelin was also assessed in cultured macrophages, smooth muscle cells, and fibroblasts. Apelin treatment resulted in diminished AAA formation, with a 47% reduction in maximal cross-sectional area (0.74 vs. 1.39 mm(2), P < 0.03) and a 57% reduction in macrophage infiltrate (113 vs. 261.3 cells/high-power field, P < 0.0001) relative to the saline-treated group. Apelin infusion was also associated with significantly reduced aortic macrophage colony-stimulating factor expression and decreased monocyte chemattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1alpha, interleukin (IL)-6, and tumor necrosis factor (TNF)-alpha mean mRNA levels. Apelin stimulation of cultured macrophages significantly reduced MCP-1 and TNF-alpha mRNA levels relative to baseline (2.03- and 1.89-fold reduction, P < 0.03, respectively) but did not affect intimal adhesion molecule expression or medial or adventitial cell cytokine production. Apelin significantly reduces aneurysm formation in the elastase model of human AAA disease. The mechanism appears to be decreased macrophage burden, perhaps related to an apelin-mediated decrease in proinflammatory cytokine and chemokine activation.

    View details for DOI 10.1152/ajpheart.01341.2008

    View details for Web of Science ID 000265659100020

    View details for PubMedID 19304942

    View details for PubMedCentralID PMC2685356

  • Clinical problem-solving. Fool's Gold. New England journal of medicine Leeper, N. J., Dhaliwal, G., Saint, S., Witteles, R. M. 2008; 359 (19): 2035-2041

    View details for DOI 10.1056/NEJMcps0802668

    View details for PubMedID 18987372

  • Apelin signaling antagonizes Ang II effects in mouse models of atherosclerosis JOURNAL OF CLINICAL INVESTIGATION Chun, H. J., Ali, Z. A., Kojima, Y., Kundu, R. K., Sheikh, A. Y., Agrawal, R., Zheng, L., Leeper, N. J., Pearl, N. E., Patterson, A. J., Anderson, J. P., Tsao, P. S., Lenardo, M. J., Ashley, E. A., Quertermous, T. 2008; 118 (10): 3343-3354

    Abstract

    Apelin and its cognate G protein-coupled receptor APJ constitute a signaling pathway with a positive inotropic effect on cardiac function and a vasodepressor function in the systemic circulation. The apelin-APJ pathway appears to have opposing physiological roles to the renin-angiotensin system. Here we investigated whether the apelin-APJ pathway can directly antagonize vascular disease-related Ang II actions. In ApoE-KO mice, exogenous Ang II induced atherosclerosis and abdominal aortic aneurysm formation; we found that coinfusion of apelin abrogated these effects. Similarly, apelin treatment rescued Ang II-mediated increases in neointimal formation and vascular remodeling in a vein graft model. NO has previously been implicated in the vasodepressor function of apelin; we found that apelin treatment increased NO bioavailability in ApoE-KO mice. Furthermore, infusion of an NO synthase inhibitor blocked the apelin-mediated decrease in atherosclerosis and aneurysm formation. In rat primary aortic smooth muscle cells, apelin inhibited Ang II-mediated transcriptional regulation of multiple targets as measured by reporter assays. In addition, we demonstrated by coimmunoprecipitation and fluorescence resonance energy transfer analysis that the Ang II and apelin receptors interacted physically. Taken together, these findings indicate that apelin signaling can block Ang II actions in vascular disease by increasing NO production and inhibiting Ang II cellular signaling.

    View details for DOI 10.1172/JCI34871

    View details for PubMedID 18769630

  • Statin use in patients with extremely low low-density lipoprotein levels is associated with improved survival CIRCULATION Leeper, N. J., Ardehali, R., DeGoma, E. M., Heidenreich, P. A. 2007; 116 (6): 613-618

    Abstract

    Aggressive lipid management has recently become the standard of care for patients with coronary heart disease. The safety and effectiveness of statin usage for patients with extremely low low-density lipoprotein (LDL) levels are less clear, however. The aim of this study was to investigate the safety and clinical outcomes of statin treatment in patients with LDL cholesterol levels below 60 mg/dL.A total of 6107 consecutive patients with LDL levels less than 60 mg/dL were identified from a tertiary care medical center or affiliated community clinic. Statin therapy was defined as a prescription during the 150 days after the low LDL value was obtained. The propensity to be treated with a statin was used to adjust the association of statin therapy and survival. A total of 4295 patients (70%) had at least 1 prescription for any medication during the 150-day observation period after the low LDL value. Their mean age was 65 years, 43% had prior ischemic heart disease, and 47% had diabetes mellitus. Statins were prescribed in 2564 patients (60%) after the low LDL value was observed. During a mean follow-up of 2.0+/-1.4 years after the observation period, there were 510 deaths. After controlling for the propensity to receive a statin, statin therapy was associated with improved survival (hazard ratio [HR], 0.65; 95% CI, 0.53 to 0.80). This lower mortality was also observed for subgroups of patients already taking statins at baseline (HR, 0.58; 95% CI, 0.38 to 0.88), those with extremely low LDL levels (<40 mg/dL, n=623; HR, 0.51; 95% CI, 0.33 to 0.79), and those without a history of ischemic heart disease (n=2438; HR, 0.58; 95% CI, 0.42 to 0.80). Statin use was not associated with an increase in malignancy, transaminase elevation, or rhabdomyolysis.Statin therapy in the setting of a very low LDL level appears to be safe and is associated with improved survival.

    View details for DOI 10.1161/CIRCULATIONAHA.107.694117

    View details for Web of Science ID 000248572300010

    View details for PubMedID 17664373

  • Prognostic value of heart rate increase at onset of exercise testing CIRCULATION Leeper, N. J., Dewey, F. E., Ashley, E. A., Sandri, M., Tan, S. Y., Hadley, D., Myers, J., Froelicher, V. 2007; 115 (4): 468-474

    Abstract

    The initial response of heart rate to dynamic exercise has been proposed as having prognostic value in limited studies that have used modalities other than the treadmill. Our aim was to evaluate the prognostic value of early heart rate parameters in patients referred for routine clinical treadmill testing.The heart rate rise at the onset of exercise was measured in 1959 patients referred for clinical treadmill testing at the Palo Alto (Calif) Veterans Affairs Medical Center from 1997 to 2004. Multivariable Cox survival analysis was performed for 197 all-cause and 74 cardiovascular deaths that accrued during a mean follow-up of 5.4+/-2.1 years. Decreased heart rate changes at all initial relative exercise workloads were associated with significantly increased all-cause mortality. The heart rate rise at one-third total exercise capacity, however, was the only early heart rate variable that significantly predicted both all-cause and cardiovascular risk after adjustment for confounders. Failing to reach 1 SD in the heart rate rise at one-third total exercise capacity was associated with a 28% increased all-cause mortality rate (hazard ratio, 0.72; 95% CI, 0.61 to 0.85; P<0.001) and a 35% cardiovascular mortality rate (hazard ratio, 0.65; 95% CI, 0.49 to 0.86; P=0.003). Of all heart rate measurements considered (initial and recovery), the heart rate increase at peak exercise was the most powerful predictor of cardiovascular prognosis after adjustment for potential confounders. The Duke treadmill score, however, was superior to all heart rate measurements in the prediction of cardiovascular mortality.In the present study population, a rapid initial heart rate rise was associated with improved survival, but the heart rate increase at peak exercise and other conventional measurements such as exercise capacity and the Duke treadmill score were more powerful predictors of prognosis.

    View details for DOI 10.1161/CIRCULATIONAHA.106.666388

    View details for PubMedID 17242274

  • Clinical problem-solving. One surprise after another. New England journal of medicine Leeper, N. J., Wener, L. S., Dhaliwal, G., Saint, S., Wachter, R. M. 2005; 352 (14): 1474-1479

    View details for PubMedID 15814884

  • Cloning of a unique lipase from endothelial cells extends the lipase gene family JOURNAL OF BIOLOGICAL CHEMISTRY Hirata, K., Dichek, H. L., Cioffi, J. A., Choi, S. Y., Leeper, N. J., Quintana, L., Kronmal, G. S., Cooper, A. D., Quertermous, T. 1999; 274 (20): 14170-14175

    Abstract

    A new lipoprotein lipase-like gene has been cloned from endothelial cells through a subtraction methodology aimed at characterizing genes that are expressed with in vitro differentiation of this cell type. The conceptual endothelial cell-derived lipase protein contains 500 amino acids, including an 18-amino acid hydrophobic signal sequence, and is 44% identical to lipoprotein lipase and 41% identical to hepatic lipase. Comparison of primary sequence to that of lipoprotein and hepatic lipase reveals conservation of the serine, aspartic acid, and histidine catalytic residues as well as the 10 cysteine residues involved in disulfide bond formation. Expression was identified in cultured human umbilical vein endothelial cells, human coronary artery endothelial cells, and murine endothelial-like yolk sac cells by Northern blot. In addition, Northern blot and in situ hybridization analysis revealed expression of the endothelial-derived lipase in placenta, liver, lung, ovary, thyroid gland, and testis. A c-Myc-tagged protein secreted from transfected COS7 cells had phospholipase A1 activity but no triglyceride lipase activity. Its tissue-restricted pattern of expression and its ability to be expressed by endothelial cells, suggests that endothelial cell-derived lipase may have unique functions in lipoprotein metabolism and in vascular disease.

    View details for Web of Science ID 000080322200064

    View details for PubMedID 10318835

  • Resolvin D1 promotes the targeting and clearance of necroptotic cells. Cell death and differentiation Gerlach, B. D., Marinello, M., Heinz, J., Rymut, N., Sansbury, B. E., Riley, C. O., Sadhu, S., Hosseini, Z., Kojima, Y., Tang, D. D., Leeper, N. J., Spite, M., Barroso, M., Rayner, K. J., Fredman, G. 2019

    Abstract

    Inflammation-resolution is a protective response that is mediated by specialized pro-resolving mediators (SPMs). The clearance of dead cells or efferocytosis is a critical cellular program of inflammation-resolution. Impaired efferocytosis can lead to tissue damage in prevalent human diseases, like atherosclerosis. Therefore understanding mechanisms associated with swift clearance of dead cells is of utmost clinical importance. Recently, the accumulation of necroptotic cells (NCs) was observed in human plaques and we postulated that this is due to defective clearance programs. Here we present evidence that NCs are inefficiently taken up by macrophages because they have increased surface expression of a well-known "don't eat me" signal called CD47. High levels of CD47 on NCs stimulated RhoA-pMLC signaling in macrophages that promoted "nibbling", rather than whole-cell engulfment of NCs. Anti-CD47 blocking antibodies limited RhoA-p-MLC signaling and promoted whole-cell NC engulfment. Treatment with anti-CD47 blocking antibodies to Ldlr-/- mice with established atherosclerosis decreased necrotic cores, limited the accumulation of plaque NCs and increased lesional SPMs, including Resolvin D1 (RvD1) compared with IgG controls. Mechanistically, RvD1 promoted whole-cell engulfment of NCs by decreasing RhoA signaling and activating CDC42. RvD1 specifically targeted NCs for engulfment by facilitating the release of the well-known "eat me signal" called calreticulin from macrophages in a CDC42 dependent manner. Lastly, RvD1 enhanced the clearance of NCs in advanced murine plaques. Together, these results suggest new molecules and signaling associated with the clearance of NCs, provide a new paradigm for the regulation of inflammation-resolution, and offer a potential treatment strategy for diseases where NCs underpin the pathology.

    View details for DOI 10.1038/s41418-019-0370-1

    View details for PubMedID 31222041

  • Incidence and Cost of Major Adverse Cardiovascular Events and Major Adverse Limb Events in Patients With Chronic Coronary Artery Disease or Peripheral Artery Disease AMERICAN JOURNAL OF CARDIOLOGY Berger, A., Simpson, A., Bhagnani, T., Leeper, N. J., Murphy, B., Nordstrom, B., Ting, W., Zhao, Q., Berger, J. S. 2019; 123 (12): 1893–99
  • A Comprehensive Evaluation of Lifestyle and Social Factors Related to Peripheral Artery Disease Events in a Large Longitudinal Study Ross, E., Leeper, N., Ingelsson, E. MOSBY-ELSEVIER. 2019: E54–E55
  • Clonal Smooth Muscle Cell Expansion, Autophagy, and Vascular Integrity in Aortic Aneurysm Disease. Arteriosclerosis, thrombosis, and vascular biology Wang, Y., Nanda, V., Leeper, N. J. 2019; 39 (6): 982–83

    View details for DOI 10.1161/ATVBAHA.119.312739

    View details for PubMedID 31116606

  • Nanoparticle Therapy for Vascular Diseases ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Flores, A. M., Ye, J., Jarr, K., Hosseini-Nassab, N., Smith, B. R., Leeper, N. J. 2019; 39 (4): 635–46
  • Predicting Future Cardiovascular Events in Patients With Peripheral Artery Disease Using Electronic Health Record Data CIRCULATION-CARDIOVASCULAR QUALITY AND OUTCOMES Ross, E., Jung, K., Dudley, J. T., Li, L., Leeper, N. J., Shah, N. H. 2019; 12 (3)
  • Predicting Future Cardiovascular Events in Patients With Peripheral Artery Disease Using Electronic Health Record Data. Circulation. Cardiovascular quality and outcomes Ross, E. G., Jung, K., Dudley, J. T., Li, L., Leeper, N. J., Shah, N. H. 2019; 12 (3): e004741

    Abstract

    BACKGROUND: Patients with peripheral artery disease (PAD) are at risk of major adverse cardiac and cerebrovascular events. There are no readily available risk scores that can accurately identify which patients are most likely to sustain an event, making it difficult to identify those who might benefit from more aggressive intervention. Thus, we aimed to develop a novel predictive model-using machine learning methods on electronic health record data-to identify which PAD patients are most likely to develop major adverse cardiac and cerebrovascular events.METHODS AND RESULTS: Data were derived from patients diagnosed with PAD at 2 tertiary care institutions. Predictive models were built using a common data model that allowed for utilization of both structured (coded) and unstructured (text) data. Only data from time of entry into the health system up to PAD diagnosis were used for modeling. Models were developed and tested using nested cross-validation. A total of 7686 patients were included in learning our predictive models. Utilizing almost 1000 variables, our best predictive model accurately determined which PAD patients would go on to develop major adverse cardiac and cerebrovascular events with an area under the curve of 0.81 (95% CI, 0.80-0.83).CONCLUSIONS: Machine learning algorithms applied to data in the electronic health record can learn models that accurately identify PAD patients at risk of future major adverse cardiac and cerebrovascular events, highlighting the great potential of electronic health records to provide automated risk stratification for cardiovascular diseases. Common data models that can enable cross-institution research and technology development could potentially be an important aspect of widespread adoption of newer risk-stratification models.

    View details for PubMedID 30857412

  • Nanoparticle Therapy for Vascular Diseases. Arteriosclerosis, thrombosis, and vascular biology Flores, A. M., Ye, J., Jarr, K., Hosseini-Nassab, N., Smith, B. R., Leeper, N. J. 2019: ATVBAHA118311569

    Abstract

    Nanoparticles promise to advance strategies to treat vascular disease. Since being harnessed by the cancer field to deliver safer and more effective chemotherapeutics, nanoparticles have been translated into applications for cardiovascular disease. Systemic exposure and drug-drug interactions remain a concern for nearly all cardiovascular therapies, including statins, antithrombotic, and thrombolytic agents. Moreover, off-target effects and poor bioavailability have limited the development of completely new approaches to treat vascular disease. Through the rational design of nanoparticles, nano-based delivery systems enable more efficient delivery of a drug to its therapeutic target or even directly to the diseased site, overcoming biological barriers and enhancing a drug's therapeutic index. In addition, advances in molecular imaging have led to the development of theranostic nanoparticles that may simultaneously act as carriers of both therapeutic and imaging payloads. The following is a summary of nanoparticle therapy for atherosclerosis, thrombosis, and restenosis and an overview of recent major advances in the targeted treatment of vascular disease.

    View details for PubMedID 30786744

  • Incidence and Cost of Major Adverse Cardiovascular Events and Major Adverse Limb Events in Patients With Chronic Coronary Artery Disease or Peripheral Artery Disease. The American journal of cardiology Berger, A., Simpson, A., Bhagnani, T., Leeper, N. J., Murphy, B., Nordstrom, B., Ting, W., Zhao, Q., Berger, J. S. 2019

    Abstract

    Chronic coronary artery disease (CAD) and peripheral artery disease (PAD) are both associated with elevated risks of major adverse cardiovascular events (MACE) and major adverse limb events (MALE). The frequency of these events in patients with CAD or PAD, and their corresponding costs, are not well understood. Accordingly, we describe the incidence and cost of both MACE and MALE in patients with CAD or PAD. Using a database that included healthcare claims linked to electronic medical records, we identified patients with evidence of chronic CAD and PAD, respectively, between January 1, 2009, and September 30, 2016. We assessed the occurrence of MACE (defined as myocardial infarction, stroke, or cardiovascular-related death) and MALE (critical limb ischemia, amputation, or peripheral artery disease-related revascularization). A total of 99,730 patients met all selection criteria: 86.0% had CAD, 25.8% had PAD, and 11.8% had both. Mean (±standard deviation) age was 67.7 (±11.5) years and 59.8% were male. During follow-up (mean: 1.8 years), 13.6% experienced MACE or MALE (6.3 per 100 person-years [PYs]), predominantly MACE (9.6% [4.3 per 100 PYs]). Adjusted 1-year healthcare costs were $44,495 greater in patients who experienced MACE or MALE (mean [95% confidence interval]: $64,099 [$33,254 to $123,557] vs $19,604 [$10,175 to $37,771]; p < 0.001). In conclusion, approximately 1 in 7 patients with chronic CAD or PAD experiences additional MACE or MALE within approximately 2 years of follow-up; the relatively high risk and cost of these events highlight the need for new secondary prevention therapies that may improve outcomes in these patients.

    View details for PubMedID 31014542

  • Smooth Muscle Cells Contribute the Majority of Foam Cells in ApoE (Apolipoprotein E)-Deficient Mouse Atherosclerosis. Arteriosclerosis, thrombosis, and vascular biology Wang, Y., Dubland, J. A., Allahverdian, S., Asonye, E., Sahin, B., Jaw, J. E., Sin, D. D., Seidman, M. A., Leeper, N. J., Francis, G. A. 2019; 39 (5): 876–87

    Abstract

    Objective- Smooth muscle cells (SMCs) are the most abundant cells in human atherosclerotic lesions and are suggested to contribute at least 50% of atheroma foam cells. In mice, SMCs contribute fewer total lesional cells. The purpose of this study was to determine the contribution of SMCs to total foam cells in apolipoprotein E-deficient (ApoE-/-) mice, and the utility of these mice to model human SMC foam cell biology and interventions. Approach and Results- Using flow cytometry, foam cells in the aortic arch of ApoE-/- mice were characterized based on the expression of leukocyte-specific markers. Nonleukocyte foam cells increased from 37% of total foam cells in 27-week-old to 75% in 57-week-old male ApoE-/- mice fed a chow diet and were ≈70% in male and female ApoE-/- mice following 6 weeks of Western diet feeding. A similar contribution to total foam cells by SMCs was found using SMC-lineage tracing ApoE-/- mice fed the Western diet for 6 or 12 weeks. Nonleukocyte foam cells contributed a similar percentage of total atheroma cholesterol and exhibited lower expression of the cholesterol exporter ABCA1 (ATP-binding cassette transporter A1) when compared with leukocyte-derived foam cells. Conclusions- Consistent with previous studies of human atheromas, we present evidence that SMCs contribute the majority of atheroma foam cells in ApoE-/- mice fed a Western diet and a chow diet for longer periods. Reduced expression of ABCA1, also seen in human intimal SMCs, suggests a common mechanism for formation of SMC foam cells across species, and represents a novel target to enhance atherosclerosis regression.

    View details for PubMedID 30786740

  • Smooth muscle cells contribute the majority of foam cells in apolipoprotein E-deficient mouse atherosclerosis Arteriosclerosis, Thrombosis, and Vascular Biology (In press) Wang, Y., Dubland, J., Allahverdian, S., Asonye, E., Sahin, B., Jaw, J., Sin, D., Seidman, M., Leeper, N., Francis, G. 2019 : 876–87

    Abstract

    Objective- Smooth muscle cells (SMCs) are the most abundant cells in human atherosclerotic lesions and are suggested to contribute at least 50% of atheroma foam cells. In mice, SMCs contribute fewer total lesional cells. The purpose of this study was to determine the contribution of SMCs to total foam cells in apolipoprotein E-deficient (ApoE-/-) mice, and the utility of these mice to model human SMC foam cell biology and interventions. Approach and Results- Using flow cytometry, foam cells in the aortic arch of ApoE-/- mice were characterized based on the expression of leukocyte-specific markers. Nonleukocyte foam cells increased from 37% of total foam cells in 27-week-old to 75% in 57-week-old male ApoE-/- mice fed a chow diet and were ≈70% in male and female ApoE-/- mice following 6 weeks of Western diet feeding. A similar contribution to total foam cells by SMCs was found using SMC-lineage tracing ApoE-/- mice fed the Western diet for 6 or 12 weeks. Nonleukocyte foam cells contributed a similar percentage of total atheroma cholesterol and exhibited lower expression of the cholesterol exporter ABCA1 (ATP-binding cassette transporter A1) when compared with leukocyte-derived foam cells. Conclusions- Consistent with previous studies of human atheromas, we present evidence that SMCs contribute the majority of atheroma foam cells in ApoE-/- mice fed a Western diet and a chow diet for longer periods. Reduced expression of ABCA1, also seen in human intimal SMCs, suggests a common mechanism for formation of SMC foam cells across species, and represents a novel target to enhance atherosclerosis regression.

    View details for DOI 10.1161/ATVBAHA.119.312434

  • Clinical and Genetic Determinants of Varicose Veins. Circulation Fukaya, E., Flores, A. M., Lindholm, D., Gustafsson, S., Zanetti, D., Ingelsson, E., Leeper, N. J. 2018; 138 (25): 2869–80

    Abstract

    BACKGROUND: Varicose veins are a common problem with no approved medical therapies. Although it is believed that varicose vein pathogenesis is multifactorial, there is limited understanding of the genetic and environmental factors that contribute to their formation. Large-scale studies of risk factors for varicose veins may highlight important aspects of pathophysiology and identify groups at increased risk for disease.METHODS: We applied machine learning to agnostically search for risk factors of varicose veins in 493519 individuals in the UK Biobank. Predictors were further studied with univariable and multivariable Cox regression analyses (2441 incident events). A genome-wide association study of varicose veins was also performed among 337536 unrelated individuals (9577 cases) of white British descent, followed by expression quantitative loci and pathway analyses. Because height emerged as a new candidate risk factor, we performed mendelian randomization analyses to assess a potential causal role for height in varicose vein development.RESULTS: Machine learning confirmed several known (age, sex, obesity, pregnancy, history of deep vein thrombosis) and identified several new risk factors for varicose vein disease, including height. After adjustment for traditional risk factors in Cox regression, greater height remained independently associated with varicose veins (hazard ratio for upper versus lower quartile, 1.74; 95% CI, 1.51-2.01; P<0.0001). A genome-wide association study identified 30 new genome-wide significant loci, identifying pathways involved in vascular development and skeletal/limb biology. Mendelian randomization analysis provided evidence that increased height is causally related to varicose veins (inverse-variance weighted: odds ratio, 1.26; P=2.07*10-16).CONCLUSIONS: Using data from nearly a half-million individuals, we present a comprehensive genetic and epidemiological study of varicose veins. We identified novel clinical and genetic risk factors that provide pathophysiological insights and could help future improvements of treatment of varicose vein disease.

    View details for PubMedID 30566020

  • Functional regulatory mechanism of smooth muscle cell-restricted LMOD1 coronary artery disease locus PLOS GENETICS Nanda, V., Wang, T., Pjanic, M., Liu, B., Trieu Nguyen, Matic, L., Hedin, U., Koplev, S., Ma, L., Franzen, O., Ruusalepp, A., Schadt, E. E., Bjorkegren, J. M., Montgomery, S. B., Snyder, M. P., Quertermous, T., Leeper, N. J., Miller, C. L. 2018; 14 (11)
  • Association of Blood Pressure Measurements With Peripheral Artery Disease Events: Reanalysis of the ALLHAT Data CIRCULATION Itoga, N. K., Tawfik, D. S., Lee, C. K., Maruyama, S., Leeper, N. J., Chang, T. I. 2018; 138 (17): 1805–14
  • Loss of CDKN2B Promotes Fibrosis via Increased Fibroblast Differentiation Rather Than Proliferation AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY Scruggs, A. M., Koh, H. B., Tripathi, P., Leeper, N. J., White, E. S., Huang, S. K. 2018; 59 (2): 200–214

    Abstract

    Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease characterized by excessive scarring and fibroblast activation. We previously showed that fibroblasts from patients with IPF are hypermethylated at the CDKN2B gene locus, resulting in decreased CDKN2B expression. Here, we examine how diminished CDKN2B expression in normal and IPF fibroblasts affect fibroblast function, and how loss of CDKN2B contributes to IPF pathogenesis. We first confirmed that protein expression of CDKN2B was diminished in IPF lungs in situ. Loss of CDKN2B was especially notable in regions of increased myofibroblasts and fibroblastic foci. The degree of CDKN2B hypermethylation was particularly elevated in patients with radiographic honeycombing, a marker of more advanced fibrosis, and increased DNA methylation correlated with decreased expression. Although CDKN2B is traditionally considered a cell cycle inhibitor, loss of CDKN2B did not result in an increase in fibroblast proliferation, but instead was associated with an increase in myofibroblast differentiation. An increase in myofibroblast differentiation was not observed when CDKN2A was silenced. Loss of CDKN2B was associated with an increase in the transcription factors serum response factor and myocardin-related transcription factor A, and overexpression of CDKN2B in IPF fibroblasts inhibited myofibroblast differentiation. Finally, decreased CDKN2B expression was noted in fibroblasts from a murine model of fibrosis, and Cdkn2b-/- mice developed greater histologic fibrosis after bleomycin injury. These findings identify a novel function for CDKN2B that differs from its conventional designation as a cell cycle inhibitor and demonstrate the importance of this protein in pulmonary fibrosis.

    View details for PubMedID 29420051

  • Bioimpedance and New-Onset Heart Failure: A Longitudinal Study of >500 000 Individuals From the General Population JOURNAL OF THE AMERICAN HEART ASSOCIATION Lindholm, D., Fukaya, E., Leeper, N. J., Ingelsson, E. 2018; 7 (13)

    Abstract

    Heart failure constitutes a high burden on patients and society, but although lifetime risk is high, it is difficult to predict without costly or invasive testing. We aimed to establish new risk factors of heart failure, which potentially could enable early diagnosis and preemptive treatment.We applied machine learning in the UK Biobank in an agnostic search of risk factors for heart failure in 500 451 individuals, excluding individuals with prior heart failure. Novel factors were then subjected to several in-depth analyses, including multivariable Cox models of incident heart failure, and assessment of discrimination and calibration. Machine learning confirmed many known and putative risk factors for heart failure and identified several novel candidates. Mean reticulocyte volume appeared as one novel factor and leg bioimpedance another, the latter appearing as the most important new marker. Leg bioimpedance was lower in those who developed heart failure during an up to 9.8-year follow-up. When adjusting for known heart failure risk factors, leg bioimpedance was inversely related to heart failure (hazard ratio [95% confidence interval], 0.60 [0.48-0.73] and 0.75 [0.59-0.94], in age- and sex-adjusted and fully adjusted models, respectively, comparing the upper versus lower quartile). A model including leg bioimpedance, age, sex, and self-reported history of myocardial infarction showed good discrimination for future heart failure hospitalization (Concordance index [C-index]=0.82) and good calibration.Leg bioimpedance is inversely associated with heart failure incidence in the general population. A simple model of exclusively noninvasive measures, combining leg bioimpedance with history of myocardial infarction, age, and sex provides accurate predictive capacity.

    View details for PubMedID 29959136

  • Association of Blood Pressure Measurements with Peripheral Arterial Disease Events: A Reanalysis of the ALLHAT Data. Circulation Itoga, N. K., Tawfik, D. S., Lee, C. K., Maruyama, S., Leeper, N. J., Chang, T. I. 2018

    Abstract

    Background -Current guidelines recommend treating hypertension in patients with peripheral arterial disease (PAD) to reduce the risk of cardiac events and stroke, but the effect of reducing blood pressure on lower extremity PAD events is largely unknown. We investigated the association of blood pressure with lower extremity PAD events using data from the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). Methods -ALLHAT investigated the effect of different antihypertensive medication classes (chlorthalidone, amlodipine, lisinopril, or doxazosin) on cardiovascular events. Using these data, the primary outcome in our analysis was time to first lower extremity PAD event, defined as PAD-related hospitalization, procedures, medical treatment, or PAD-related death. Given the availability of longitudinal standardized blood pressure measurements, we analyzed systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP) as time-varying categorical variables (reference categories 120-129 mm Hg for SBP, 70-79 mm Hg for DBP, and 45-54 mm Hg for PP) in separate models. We used extended Cox regression with death as a competing risk to calculate the association of each BP component with PAD events, and report the results as sub-distribution hazard ratios (HR) and 95% confidence intervals (CI). Results -The present analysis included 33,357 patients with an average age of 67.4 years, 53.1% men, 59.7% white race, and 36.2% with diabetes mellitus. The median baseline blood pressure was 146/84 mm Hg. Participants were followed for a median of 4.3 (IQR 3.6-5.3) years, during which time 1,489 (4.5%) had a lower extremity PAD event, and 4,148 (12.4%) died. In models adjusted for demographic and clinical characteristics, SBP <120 mm Hg was associated with a 26% (CI 5-52%, P=0.015) higher hazard and SBP≥160 mm Hg was associated with a 21% (CI 0-48%, P=0.050) higher hazard for a PAD event, compared with SBP 120-129 mm Hg. In contrast, lower, but not higher, DBP was associated with higher hazard of PAD events: for DBP <60 mm Hg HR = 1.72 (CI 1.38 - 2.16). PP had a U-shaped association with PAD events. Conclusions -In this re-analysis of data from ALLHAT, we found a higher rate of lower extremity PAD events with higher and lower SBP and PP, and with lower DBP. Given the recent revised blood pressure guidelines advocating lower SBP targets for overall cardiovascular risk reduction, further refinement of optimal blood pressure targets specific to PAD is needed. Clinical Trial Registration -URL: www.clinicaltrials.gov Unique identifier: NCT00000542.

    View details for PubMedID 29930023

  • Clinical and genetic determinants of varicose veins: a prospective, community-based prospective study of similar to 500,000 individuals Fukaya, E., Flores, A., Lindholm, D., Gustafsson, S., Ingelsson, E., Leeper, N. SAGE PUBLICATIONS LTD. 2018: 300
  • Thrombotic Regulation From the Endothelial Cell Perspectives ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Wang, M., Hao, H., Leeper, N. J., Zhu, L., Early Career Comm 2018; 38 (6): E90–E95

    View details for PubMedID 29793992

  • Non-coding RNAs: key regulators of smooth muscle cell fate in vascular disease CARDIOVASCULAR RESEARCH Leeper, N. J., Maegdefessel, L. 2018; 114 (4): 611–21

    Abstract

    The vascular smooth muscle cell (SMC) is one of the most plastic cells in the body. Understanding how non-coding RNAs (ncRNAs) regulate SMC cell-fate decision making in the vasculature has significantly enhanced our understanding of disease development, and opened up exciting new avenues for potential therapeutic applications. Recent studies on SMC physiology have in addition challenged our traditional view on their role and contribution to vascular disease, mainly in the setting of atherosclerosis as well as aneurysm disease, and restenosis after angioplasties. The impact of SMC behaviour on vascular disease is now recognized to be context dependent; SMC proliferation and migration can be harmful or beneficial, whereas their apoptosis, senescence, and switching into a more macrophage-like phenotype can promote inflammation and disease progression. This is in particular true for atherosclerosis-related diseases, where proliferation of SMCs was believed to promote lesion formation, but may also prevent plaque rupture by stabilizing the fibrous cap. Based on newer findings of genetic lineage tracing studies, it was revealed that SMC phenotypic switching can result in less-differentiated forms that lack classical SMC markers while exhibiting functions more related to macrophage-like cells. This switching can directly promote atherogenesis. The aim of this current review is to summarize and discuss how ncRNAs (mainly microRNAs and long ncRNAs) are involved in SMC plasticity, and how they directly affect vascular disease development and progression. Finally, we want to critically assess where potential future therapies could be useful to influence the burden of vascular diseases.

    View details for PubMedID 29300828

    View details for PubMedCentralID PMC5852528

  • Consideration of Sex Differences in Design and Reporting of Experimental Arterial Pathology Studies-Statement From ATVB Council ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Robinet, P., Milewicz, D. M., Cassis, L. A., Leeper, N. J., Lu, H. S., Smith, J. D. 2018; 38 (2): 292–303

    Abstract

    There are many differences in arterial diseases between men and women, including prevalence, clinical manifestations, treatments, and prognosis. The new policy of the National Institutes of Health, which requires the inclusion of sex as a biological variable for preclinical studies, aims to foster new mechanistic insights and to enhance our understanding of sex differences in human diseases. The purpose of this statement is to suggest guidelines for designing and reporting sex as a biological variable in animal models of atherosclerosis, thoracic and abdominal aortic aneurysms, and peripheral arterial disease. We briefly review sex differences of these human diseases and their animal models, followed by suggestions on experimental design and reporting of animal studies for these vascular pathologies.

    View details for PubMedID 29301789

    View details for PubMedCentralID PMC5785439

  • Trends in Rates of Lower Extremity Amputation Among Patients With End-Stage Renal Disease Who Receive Dialysis JAMA Internal Medicine Franz, D., Zheng, Y., Leeper, N. J., Chandra, V., Montez-Rath, M., Chang, T. I. 2018
  • Functional regulatory mechanism of smooth muscle cell-restricted LMOD1 coronary artery disease locus. PLoS genetics Nanda, V., Wang, T., Pjanic, M., Liu, B., Nguyen, T., Matic, L. P., Hedin, U., Koplev, S., Ma, L., Franzén, O., Ruusalepp, A., Schadt, E. E., Björkegren, J. L., Montgomery, S. B., Snyder, M. P., Quertermous, T., Leeper, N. J., Miller, C. L. 2018; 14 (11): e1007755

    Abstract

    Recent genome-wide association studies (GWAS) have identified multiple new loci which appear to alter coronary artery disease (CAD) risk via arterial wall-specific mechanisms. One of the annotated genes encodes LMOD1 (Leiomodin 1), a member of the actin filament nucleator family that is highly enriched in smooth muscle-containing tissues such as the artery wall. However, it is still unknown whether LMOD1 is the causal gene at this locus and also how the associated variants alter LMOD1 expression/function and CAD risk. Using epigenomic profiling we recently identified a non-coding regulatory variant, rs34091558, which is in tight linkage disequilibrium (LD) with the lead CAD GWAS variant, rs2820315. Herein we demonstrate through expression quantitative trait loci (eQTL) and statistical fine-mapping in GTEx, STARNET, and human coronary artery smooth muscle cell (HCASMC) datasets, rs34091558 is the top regulatory variant for LMOD1 in vascular tissues. Position weight matrix (PWM) analyses identify the protective allele rs34091558-TA to form a conserved Forkhead box O3 (FOXO3) binding motif, which is disrupted by the risk allele rs34091558-A. FOXO3 chromatin immunoprecipitation and reporter assays show reduced FOXO3 binding and LMOD1 transcriptional activity by the risk allele, consistent with effects of FOXO3 downregulation on LMOD1. LMOD1 knockdown results in increased proliferation and migration and decreased cell contraction in HCASMC, and immunostaining in atherosclerotic lesions in the SMC lineage tracing reporter mouse support a key role for LMOD1 in maintaining the differentiated SMC phenotype. These results provide compelling functional evidence that genetic variation is associated with dysregulated LMOD1 expression/function in SMCs, together contributing to the heritable risk for CAD.

    View details for PubMedID 30444878

  • Trends in Rates of Lower Extremity Amputation Among Patients With End-stage Renal Disease Who Receive Dialysis. JAMA internal medicine Franz, D., Zheng, Y., Leeper, N. J., Chandra, V., Montez-Rath, M., Chang, T. I. 2018

    Abstract

    Patients with end-stage renal disease (ESRD) who receive dialysis are at high risk of lower extremity amputation. Recent studies indicate decreasing rates of lower extremity amputation in non-ESRD populations, but contemporary data for patients with ESRD who receive dialysis are lacking.To assess rates of lower extremity amputation among patients with ESRD who receive dialysis during a recent 15-year period; to analyze whether those rates differed by age, sex, diabetes, or geographic region; and to determine 1-year mortality rates in this population after lower extremity amputation.This retrospective study of 3 700 902 records obtained from a US national registry of patients with ESRD who receive dialysis assessed cross-sectional cohorts for each calendar year from 2000 through 2014. Adult patients with prevalent ESRD treated with hemodialysis or peritoneal dialysis covered by Medicare Part A and B on January 1 of each cohort year were included. Data analysis was conducted from August 2017 to April 2018.Age, sex, diabetes, and hospital referral region.Annual rates per 100 person-years of nontraumatic major (above- or below-knee) and minor (below-ankle) amputations.For each annual cohort, there were fewer women (47.5% in 2000, 46.2% in 2005, 44.9% in 2010, and 44.0% in 2014) than men, more than half the patients were white individuals (58.1% in 2000, 56.9% in 2005, 56.9% in 2010, and 56.7% in 2014), and a small proportion were employed (13.9% in 2000, 15.1% in 2005, 16.1% in 2010, and 16.5% in 2014). The rate of lower extremity amputations for patients with ESRD who receive dialysis decreased by 51.0% from 2000 to 2014, driven primarily by a decrease in the rate of major amputations (5.42 [95% CI, 5.28-5.56] in 2000 vs 2.66 [95% CI, 2.59-2.72] per 100 person-years in 2014). Patients with diabetes had amputation rates more than 5 times as high as patients without diabetes. Patients younger than 65 years had higher adjusted amputation rates than older patients, and men had consistently higher adjusted amputation rates than women. Adjusted 1-year mortality rates after lower extremity amputation for patients with ESRD who receive dialysis decreased from 52.2% (95% CI, 50.9%-53.4%) in 2000 to 43.6% (95% CI, 42.5%-44.8%) in 2013. In general, amputation rates decreased among all regions from 2000 to 2014, but regional variability persisted across time despite adjustment for differences in patient demographics and comorbid conditions.Although rates of lower extremity amputations among US patients with ESRD who receive dialysis decreased by 51% during a recent 15-year period, mortality rates remained high, with nearly half of patients dying within a year after lower extremity amputation. Our results highlight the need for more research on ways to prevent lower extremity amputation in this extremely high-risk population.

    View details for PubMedID 29987332

  • A Missing LNC in Vascular Diseases CIRCULATION RESEARCH Cooke, J. P., Leeper, N. J. 2017; 121 (4): 320–22

    View details for PubMedID 28775007

    View details for PubMedCentralID PMC5637485

  • MiRNA-210 Enhances Fibrous Cap Stability in Advanced Atherosclerotic Lesions Eken, S. M., Jin, H., Chernogubova, E., Li, Y., Simon, N., Sun, C., Korzunowicz, G., Busch, A., Backlund, A., Osterholm, C., Razuvaev, A., Renne, T., Eckstein, H. H., Pelisek, J., Eriksson, P., Diez, M., Perisic, L., Schellinger, I. N., Raaz, U., Leeper, N. J., Hansson, G. K., Paulsson-Berne, G., Hedin, U., Maegdefessel, L. LIPPINCOTT WILLIAMS & WILKINS. 2017
  • A CD47-associated super-enhancer links pro-inflammatory signalling to CD47 upregulation in breast cancer NATURE COMMUNICATIONS Betancur, P. A., Abraham, B. J., Yiu, Y. Y., Willingham, S. B., Khameneh, F., Zarnegar, M., Kuo, A. H., McKenna, K., Kojima, Y., Leeper, N. J., Ho, P., Gip, P., Swigut, T., Sherwood, R. I., Clarke, M. F., Somlo, G., Young, R. A., Weissman, I. L. 2017; 8

    Abstract

    CD47 is a cell surface molecule that inhibits phagocytosis of cells that express it by binding to its receptor, SIRPα, on macrophages and other immune cells. CD47 is expressed at different levels by neoplastic and normal cells. Here, to reveal mechanisms by which different neoplastic cells generate this dominant 'don't eat me' signal, we analyse the CD47 regulatory genomic landscape. We identify two distinct super-enhancers (SEs) associated with CD47 in certain cancer cell types. We show that a set of active constituent enhancers, located within the two CD47 SEs, regulate CD47 expression in different cancer cell types and that disruption of CD47 SEs reduces CD47 gene expression. Finally we report that the TNF-NFKB1 signalling pathway directly regulates CD47 by interacting with a constituent enhancer located within a CD47-associated SE specific to breast cancer. These results suggest that cancers can evolve SE to drive CD47 overexpression to escape immune surveillance.

    View details for DOI 10.1038/ncomms14802

    View details for Web of Science ID 000398343600001

    View details for PubMedID 28378740

  • The Intersection of Genome-Wide Association Studies and High-Throughput Small Interfering Ribonucleic Acid Screens Allows for the Identification of Novel Pathways Relevant to Atherosclerosis. JACC. Basic to translational science Nanda, V., Xiao, S., Ye, J., Leeper, N. J. 2017; 2 (2): 209–11

    Abstract

    It is now known that the internalization and transcytosis of low density lipoprotein (LDL) in the vessel wall occurs through molecular pathways independent of the LDL receptor. In a study recently published in Nature Communications, investigators cross-referenced results from a genome-wide ribonucleic acid interference screen with targets identified in publicly-available genome-wide association studies datasets to identify activin-like kinase 1 as a novel driver of this process. This approach has relevance to the field of atherosclerosis, and could be used as a model for the prioritization of future "hits" in large-scale genomic screens.

    View details for PubMedID 30167568

  • "Attack of the Clones": Commonalities Between Cancer and Atherosclerosis. Circulation research DiRenzo, D., Owens, G. K., Leeper, N. J. 2017; 120 (4): 624-626

    View details for DOI 10.1161/CIRCRESAHA.116.310091

    View details for PubMedID 28209794

  • Evaluation of Cell Therapy on Exercise Performance and Limb Perfusion in Peripheral Artery Disease: The CCTRN Patients with Intermittent Claudication Injected with ALDH Bright Cells (PACE) Trial. Circulation Perin, E. C., Murphy, M. P., March, K. L., Bolli, R., Loughran, J., Yang, P. C., Leeper, N. J., Dalman, R. L., Alexander, J. Q., Henry, T. D., Traverse, J. H., Pepine, C. J., Anderson, R. D., Berceli, S., Willerson, J. T., Muthupillai, R., Gahremanpour, A. A., Raveendran, G., Velazquez, O. C., Hare, J. M., Schulman, I. H., Kasi, V. S., Hiatt, W. R., Ambale-Venkatesh, B., Lima, J. A., Taylor, D. A., Resende, M. M., Gee, A. P., Durett, A. G., Bloom, J., Richman, S., G'Sell, P., Williams, S., Khan, F., Ross, E. G., Santoso, M. R., Goldman, J., Leach, D., Handberg, E., Cheong, B. Y., Piece, N. A., Difede, D., Bruhn-Ding, B., Caldwell, E., Bettencourt, J., Lai, D., Piller, L. B., Simpson, L. M., Cohen, M., Sayre, S. L., Vojvodic, R. W., Moyé, L., Ebert, R. F., Simari, R. D., Hirsch, A. T. 2017

    Abstract

    Atherosclerotic peripheral artery disease affects 8% to 12% of Americans >65 years of age and is associated with a major decline in functional status, increased myocardial infarction and stroke rates, and increased risk of ischemic amputation. Current treatment strategies for claudication have limitations. PACE (Patients With Intermittent Claudication Injected With ALDH Bright Cells) is a National Heart, Lung, and Blood Institute-sponsored, randomized, double-blind, placebo-controlled, phase 2 exploratory clinical trial designed to assess the safety and efficacy of autologous bone marrow-derived aldehyde dehydrogenase bright (ALDHbr) cells in patients with peripheral artery disease and to explore associated claudication physiological mechanisms.All participants, randomized 1:1 to receive ALDHbr cells or placebo, underwent bone marrow aspiration and isolation of ALDHbr cells, followed by 10 injections into the thigh and calf of the index leg. The coprimary end points were change from baseline to 6 months in peak walking time (PWT), collateral count, peak hyperemic popliteal flow, and capillary perfusion measured by magnetic resonance imaging, as well as safety.A total of 82 patients with claudication and infrainguinal peripheral artery disease were randomized at 9 sites, of whom 78 had analyzable data (57 male, 21 female patients; mean age, 66±9 years). The mean±SEM differences in the change over 6 months between study groups for PWT (0.9±0.8 minutes; 95% confidence interval [CI] -0.6 to 2.5; P=0.238), collateral count (0.9±0.6 arteries; 95% CI, -0.2 to 2.1; P=0.116), peak hyperemic popliteal flow (0.0±0.4 mL/s; 95% CI, -0.8 to 0.8; P=0.978), and capillary perfusion (-0.2±0.6%; 95% CI, -1.3 to 0.9; P=0.752) were not significant. In addition, there were no significant differences for the secondary end points, including quality-of-life measures. There were no adverse safety outcomes. Correlative relationships between magnetic resonance imaging measures and PWT were not significant. A post hoc exploratory analysis suggested that ALDHbr cell administration might be associated with an increase in the number of collateral arteries (1.5±0.7; 95% CI, 0.1-2.9; P=0.047) in participants with completely occluded femoral arteries.ALDHbr cell administration did not improve PWT or magnetic resonance outcomes, and the changes in PWT were not associated with the anatomic or physiological magnetic resonance imaging end points. Future peripheral artery disease cell therapy investigational trial design may be informed by new anatomic and perfusion insights.URL: http://www.clinicaltrials.gov. Unique identifier: NCT01774097.

    View details for DOI 10.1161/CIRCULATIONAHA.116.025707

    View details for PubMedID 28209728

  • MicroRNA-210 Enhances Fibrous Cap Stability in Advanced Atherosclerotic Lesions CIRCULATION RESEARCH Eken, S. M., Jin, H., Chernogubova, E., Li, Y., Simon, N., Sun, C., Korzunowicz, G., Busch, A., Backlund, A., Osterholm, C., Razuvaev, A., Renne, T., Eckstein, H. H., Pelisek, J., Eriksson, P., Diez, M. G., Matic, L. P., Schellinger, I. N., Raaz, U., Leeper, N. J., Hansson, G. K., Paulsson-Berne, G., Hedin, U., Maegdefessel, L. 2017; 120 (4): 633-?

    Abstract

    In the search for markers and modulators of vascular disease, microRNAs (miRNAs) have emerged as potent therapeutic targets.To investigate miRNAs of clinical interest in patients with unstable carotid stenosis at risk of stroke.Using patient material from the BiKE (Biobank of Karolinska Endarterectomies), we profiled miRNA expression in patients with stable versus unstable carotid plaque. A polymerase chain reaction-based miRNA array of plasma, sampled at the carotid lesion site, identified 8 deregulated miRNAs (miR-15b, miR-29c, miR-30c/d, miR-150, miR-191, miR-210, and miR-500). miR-210 was the most significantly downregulated miRNA in local plasma material. Laser capture microdissection and in situ hybridization revealed a distinct localization of miR-210 in fibrous caps. We confirmed that miR-210 directly targets the tumor suppressor gene APC (adenomatous polyposis coli), thereby affecting Wnt (Wingless-related integration site) signaling and regulating smooth muscle cell survival, as well as differentiation in advanced atherosclerotic lesions. Substantial changes in arterial miR-210 were detectable in 2 rodent models of vascular remodeling and plaque rupture. Modulating miR-210 in vitro and in vivo improved fibrous cap stability with implications for vascular disease.An unstable carotid plaque at risk of stroke is characterized by low expression of miR-210. miR-210 contributes to stabilizing carotid plaques through inhibition of APC, ensuring smooth muscle cell survival. We present local delivery of miR-210 as a therapeutic approach for prevention of atherothrombotic vascular events.

    View details for DOI 10.1161/CIRCRESAHA.116.309318

    View details for Web of Science ID 000394446200016

    View details for PubMedID 27895035

  • Baseline assessment and comparison of arterial anatomy, hyperemic flow, and skeletal muscle perfusion in peripheral artery disease: The Cardiovascular Cell Therapy Research Network "Patients with Intermittent Claudication Injected with ALDH Bright Cells" (CCTRN PACE) study AMERICAN HEART JOURNAL Venkatesh, B. A., Nauffal, V., Noda, C., Fujii, T., Yang, P. C., Bettencourt, J., Ricketts, E. P., Murphy, M., Leeper, N. J., Moye, L., Ebert, R. F., Muthupillai, R., Bluemke, D. A., Perin, E. C., Hirsch, A. T., Lima, J. A. 2017; 183: 24-34

    Abstract

    Peripheral artery disease (PAD) is important to public health as a major contributor to cardiovascular morbidity and mortality. Recent developments in magnetic resonance imaging (MRI) techniques permit improved assessment of PAD anatomy and physiology, and may serve as surrogate end points after proangiogenic therapies.The PACE study is a randomized, double-blind, placebo-controlled clinical trial designed to assess the physiologic impact and potential clinical efficacy of autologous bone marrow-derived ALDH(br) stem cells. The primary MRI end points of the study are as follows: (1) total collateral count, (2) calf muscle plasma volume (a measure of capillary perfusion) by dynamic contrast-enhanced MRI, and (3) peak hyperemic popliteal flow by phase-contrast MRI (PC-MRI).The interreader and intrareader and test-retest results demonstrated good-to-excellent reproducibility (interclass correlation coefficient range 0.61-0.98) for all magnetic resonance measures. The PAD participants (n=82) had lower capillary perfusion measured by calf muscle plasma volume (3.8% vs 5.6%) and peak hyperemic popliteal flow (4.1 vs 13.5mL/s) as compared with the healthy participants (n=16), with a significant level of collateralization.Reproducibility of the MRI primary end points in PACE was very good to excellent. The PAD participants exhibited decreased calf muscle capillary perfusion as well as arterial flow reserve when compared with healthy participants. The MRI tools used in PACE may advance PAD science by enabling accurate measurement of PAD microvascular anatomy and perfusion before and after stem cell or other PAD therapies.

    View details for DOI 10.1016/j.ahj.2016.09.013

    View details for PubMedID 27979038

  • High-Density Lipoprotein Nanoparticle Imaging in Atherosclerotic Vascular Disease. JACC. Basic to translational science Leeper, N. J., Park, S. M., Smith, B. R. 2017; 2 (1): 98–100

    Abstract

    Nanoparticles promise to advance the field of cardiovascular theranostics. However, their sustained and targeted delivery remains an important obstacle. The body synthesizes some "natural" nanoparticles, including high-density lipoprotein (HDL), which may home to the atherosclerotic plaque and promote cholesterol efflux. In a recent article published in JACC: Cardiovascular Imaging, investigators generated modified, radiolabeled HDL nanoparticles and confirmed they accumulated in atherosclerotic lesions from several different species. These approaches hold promise for the noninvasive diagnosis of vulnerable plaque and in the stratification of patients in whom HDL-mimetic therapy may have a clinical benefit.

    View details for PubMedID 30167557

  • High-Density Lipoprotein Nanoparticle Imaging in Atherosclerotic Vascular Disease JACC: Basic to Translational Science Leeper, N. J., Park, S., Smith, B. R. 2017; 2 (1): 98-100
  • Association Between Androgen Deprivation Therapy and Risk of Dementia JAMA ONCOLOGY Nead, K. T., Gaskin, G., Chester, C., Swisher-McClure, S., Leeper, N. J., Shah, N. H. 2017; 3 (1): 49-55

    Abstract

    A growing body of evidence supports a link between androgen deprivation therapy (ADT) and cognitive dysfunction, including Alzheimer disease. However, it is currently unknown whether ADT may contribute to the risk of dementia more broadly.To use an informatics approach to examine the association of ADT as a treatment for prostate cancer with the subsequent development of dementia (eg, senile dementia, vascular dementia, frontotemporal dementia, and Alzheimer dementia).In this cohort study, a text-processing method was used to analyze electronic medical record data from an academic medical center from 1994 to 2013, with a median follow-up of 3.4 years (interquartile range, 1.0-7.2 years). We identified 9455 individuals with prostate cancer who were 18 years or older at diagnosis with data recorded in the electronic health record and follow-up after diagnosis. We excluded 183 patients with a previous diagnosis of dementia. Our final cohort comprised 9272 individuals with prostate cancer, including 1826 men (19.7%) who received ADT.We tested the effect of ADT on the risk of dementia using propensity score-matched Cox proportional hazards regression models and Kaplan-Meier survival analysis.Among 9272 men with prostate cancer (mean [SD] age, 66.9 [10.9] years; 5450 [58.8%] white), there was a statistically significant association between use of ADT and risk of dementia (hazard ratio, 2.17; 95% CI, 1.58-2.99; P < .001). In sensitivity analyses, results were similar when excluding patients with Alzheimer disease (hazard ratio, 2.32; 95% CI, 1.73-3.12; P < .001). The absolute increased risk of developing dementia among those who received ADT was 4.4% at 5 years (7.9% among those who received ADT vs 3.5% in those who did not receive ADT). Analyses stratified by duration of ADT found that individuals with at least 12 months of ADT use had the greatest absolute increased risk of dementia (hazard ratio, 2.36; 95% CI, 1.64-3.38; P < .001). Kaplan-Meier analysis demonstrated that ADT users 70 years or older had the lowest cumulative probability of remaining dementia free (log-rank P < .001).Androgen deprivation therapy in the treatment of prostate cancer may be associated with an increased risk of dementia. This finding should be further evaluated in prospective studies.

    View details for DOI 10.1001/jamaoncol.2016.3662

    View details for Web of Science ID 000394257300011

  • Administration of ALDH Bright Cells to Patients With Intermittent Claudication: The NHLBI CCTRN PACE Trial Perin, E. C., Murphy, M., March, K., Bolli, R., Leeper, N. J., Yang, P. C., Alexander, J., Henry, T. D., Traverse, J. H., Pepine, C. J., Willerson, J. T., Velasquez, O., Hare, J. M., Kasi, V. S., Lima, J. A., Hiatt, W. R., Taylor, D. A., Gee, A. P., Moye, L., Ebert, R. F., Simari, R. D., Hirsch, A. T. LIPPINCOTT WILLIAMS & WILKINS. 2016: E709
  • Genome-Wide Association Studies Candidate Gene to Dual Modifier of Nonalcoholic Steatohepatitis and Atherosclerosis. JACC. Basic to translational science Miller, C. L., Leeper, N. J. 2016; 1 (7): 680–83

    Abstract

    Non-alcoholic steatohepatitis (NASH) is a common disease involving chronic accumulation of fat and inflammation in the liver, often leading to advanced fibrosis, cirrhosis and cancer. It is known that NASH shares many features with atherosclerosis, however, there are still no effective therapeutics. In a recent study published in Nature, investigators demonstrate that mice lacking a high-density lipoprotein (HDL)-associated gene were surprisingly protected from both steatohepatitis and atherosclerosis through the stabilization of the liver X receptor (LXR). This work reveals a timely candidate target for two highly prevalent cardiovascular diseases.

    View details for PubMedID 28603781

  • The use of machine learning for the identification of peripheral artery disease and future mortality risk. Journal of vascular surgery Ross, E. G., Shah, N. H., Dalman, R. L., Nead, K. T., Cooke, J. P., Leeper, N. J. 2016; 64 (5): 1515-1522 e3

    Abstract

    A key aspect of the precision medicine effort is the development of informatics tools that can analyze and interpret "big data" sets in an automated and adaptive fashion while providing accurate and actionable clinical information. The aims of this study were to develop machine learning algorithms for the identification of disease and the prognostication of mortality risk and to determine whether such models perform better than classical statistical analyses.Focusing on peripheral artery disease (PAD), patient data were derived from a prospective, observational study of 1755 patients who presented for elective coronary angiography. We employed multiple supervised machine learning algorithms and used diverse clinical, demographic, imaging, and genomic information in a hypothesis-free manner to build models that could identify patients with PAD and predict future mortality. Comparison was made to standard stepwise linear regression models.Our machine-learned models outperformed stepwise logistic regression models both for the identification of patients with PAD (area under the curve, 0.87 vs 0.76, respectively; P = .03) and for the prediction of future mortality (area under the curve, 0.76 vs 0.65, respectively; P = .10). Both machine-learned models were markedly better calibrated than the stepwise logistic regression models, thus providing more accurate disease and mortality risk estimates.Machine learning approaches can produce more accurate disease classification and prediction models. These tools may prove clinically useful for the automated identification of patients with highly morbid diseases for which aggressive risk factor management can improve outcomes.

    View details for DOI 10.1016/j.jvs.2016.04.026

    View details for PubMedID 27266594

    View details for PubMedCentralID PMC5079774

  • Influence of age on androgen deprivation therapy-associated Alzheimer's disease SCIENTIFIC REPORTS Nead, K. T., Gaskin, G., Chester, C., Swisher-McClure, S., Dudley, J. T., Leeper, N. J., Shah, N. H. 2016; 6

    Abstract

    We recently found an association between androgen deprivation therapy (ADT) and Alzheimer's disease. As Alzheimer's disease is a disease of advanced age, we hypothesize that older individuals on ADT may be at greatest risk. We conducted a retrospective multi-institutional analysis among 16,888 individuals with prostate cancer using an informatics approach. We tested the effect of ADT on Alzheimer's disease using Kaplan-Meier age stratified analyses in a propensity score matched cohort. We found a lower cumulative probability of remaining Alzheimer's disease-free between non-ADT users age ≥70 versus those age <70 years (p < 0.001) and between ADT versus non-ADT users ≥70 years (p = 0.034). The 5-year probability of developing Alzheimer's disease was 2.9%, 1.9% and 0.5% among ADT users ≥70, non-ADT users ≥70 and individuals <70 years, respectively. Compared to younger individuals older men on ADT may have the greatest absolute Alzheimer's disease risk. Future work should investigate the ADT Alzheimer's disease association in advanced age populations given the greater potential clinical impact.

    View details for DOI 10.1038/srep35695

    View details for Web of Science ID 000385588200002

    View details for PubMedID 27752112

    View details for PubMedCentralID PMC5067668

  • Association Between Androgen Deprivation Therapy and Risk of Dementia. JAMA oncology Nead, K. T., Gaskin, G., Chester, C., Swisher-McClure, S., Leeper, N. J., Shah, N. H. 2016

    Abstract

    A growing body of evidence supports a link between androgen deprivation therapy (ADT) and cognitive dysfunction, including Alzheimer disease. However, it is currently unknown whether ADT may contribute to the risk of dementia more broadly.To use an informatics approach to examine the association of ADT as a treatment for prostate cancer with the subsequent development of dementia (eg, senile dementia, vascular dementia, frontotemporal dementia, and Alzheimer dementia).In this cohort study, a text-processing method was used to analyze electronic medical record data from an academic medical center from 1994 to 2013, with a median follow-up of 3.4 years (interquartile range, 1.0-7.2 years). We identified 9455 individuals with prostate cancer who were 18 years or older at diagnosis with data recorded in the electronic health record and follow-up after diagnosis. We excluded 183 patients with a previous diagnosis of dementia. Our final cohort comprised 9272 individuals with prostate cancer, including 1826 men (19.7%) who received ADT.We tested the effect of ADT on the risk of dementia using propensity score-matched Cox proportional hazards regression models and Kaplan-Meier survival analysis.Among 9272 men with prostate cancer (mean [SD] age, 66.9 [10.9] years; 5450 [58.8%] white), there was a statistically significant association between use of ADT and risk of dementia (hazard ratio, 2.17; 95% CI, 1.58-2.99; P < .001). In sensitivity analyses, results were similar when excluding patients with Alzheimer disease (hazard ratio, 2.32; 95% CI, 1.73-3.12; P < .001). The absolute increased risk of developing dementia among those who received ADT was 4.4% at 5 years (7.9% among those who received ADT vs 3.5% in those who did not receive ADT). Analyses stratified by duration of ADT found that individuals with at least 12 months of ADT use had the greatest absolute increased risk of dementia (hazard ratio, 2.36; 95% CI, 1.64-3.38; P < .001). Kaplan-Meier analysis demonstrated that ADT users 70 years or older had the lowest cumulative probability of remaining dementia free (log-rank P < .001).Androgen deprivation therapy in the treatment of prostate cancer may be associated with an increased risk of dementia. This finding should be further evaluated in prospective studies.

    View details for DOI 10.1001/jamaoncol.2016.3662

    View details for PubMedID 27737437

  • The Promise and Challenge of Induced Pluripotent Stem Cells for Cardiovascular Applications. JACC. Basic to translational science Youssef, A. A., Ross, E. G., Bolli, R., Pepine, C. J., Leeper, N. J., Yang, P. C. 2016; 1 (6): 510-523

    Abstract

    The recent discovery of human-induced pluripotent stem cells (iPSCs) has revolutionized the field of stem cells. iPSCs have demonstrated that biological development is not an irreversible process and that mature adult somatic cells can be induced to become pluripotent. This breakthrough is projected to advance our current understanding of many disease processes and revolutionize the approach to effective therapeutics. Despite the great promise of iPSCs, many translational challenges still remain. In this article, we review the basic concept of induction of pluripotency as a novel approach to understand cardiac regeneration, cardiovascular disease modeling and drug discovery. We critically reflect on the current results of preclinical and clinical studies using iPSCs for these applications with appropriate emphasis on the challenges facing clinical translation.

    View details for DOI 10.1016/j.jacbts.2016.06.010

    View details for PubMedID 28580434

  • The role of necroptosis in atherosclerotic disease. JACC. Basic to translational science Leeper, N. J. 2016; 1 (6): 548–50

    Abstract

    It is now known that cells don't always die by apoptosis, but can also undergo a process known as programmed cell necrosis, or necroptosis. In a study recently published in Science Advances, investigators reported that this pro-inflammatory process is active in human atherosclerosis, may promote growth of the necrotic core, and may serve as a novel molecular imaging and translational therapeutic target. These findings represent a major step in our goal to reduce coronary disease and stroke.

    View details for PubMedID 28480338

  • Use of Predictive Analytics for the Identification of Latent Vascular Disease and Future Adverse Cardiac Events Ross, E. G., Shah, N., Dalman, R. L., Nead, K., Leeper, N. J. MOSBY-ELSEVIER. 2016: 28S–29S
  • Statin Intensity or Achieved LDL? Practice-based Evidence for the Evaluation of New Cholesterol Treatment Guidelines PLOS ONE Ross, E. G., Shah, N., Leeper, N. 2016; 11 (5)

    Abstract

    The recently updated American College of Cardiology/American Heart Association cholesterol treatment guidelines outline a paradigm shift in the approach to cardiovascular risk reduction. One major change included a recommendation that practitioners prescribe fixed dose statin regimens rather than focus on specific LDL targets. The goal of this study was to determine whether achieved LDL or statin intensity was more strongly associated with major adverse cardiac events (MACE) using practice-based data from electronic health records (EHR).We analyzed the EHR data of more than 40,000 adult patients on statin therapy between 1995 and 2013. Demographic and clinical variables were extracted from coded data and unstructured clinical text. To account for treatment selection bias we performed propensity score stratification as well as 1:1 propensity score matched analyses. Conditional Cox proportional hazards modeling was used to identify variables associated with MACE.We identified 7,373 adults with complete data whose cholesterol appeared to be actively managed. In a stratified propensity score analysis of the entire cohort over 3.3 years of follow-up, achieved LDL was a significant predictor of MACE outcome (Hazard Ratio 1.1; 95% confidence interval, 1.05-1.2; P < 0.0004), while statin intensity was not. In a 1:1 propensity score matched analysis performed to more aggressively control for covariate balance between treatment groups, achieved LDL remained significantly associated with MACE (HR 1.3; 95% CI, 1.03-1.7; P = 0.03) while treatment intensity again was not a significant predictor.Using EHR data we found that on-treatment achieved LDL level was a significant predictor of MACE. Statin intensity alone was not associated with outcomes. These findings imply that despite recent guidelines, achieved LDL levels are clinically important and LDL titration strategies warrant further investigation in clinical trials.

    View details for DOI 10.1371/journal.pone.0154952

    View details for Web of Science ID 000376882500009

    View details for PubMedID 27227451

    View details for PubMedCentralID PMC4881915

  • Androgen Deprivation Therapy and Future Alzheimer's Disease Risk. Journal of clinical oncology Nead, K. T., Gaskin, G., Chester, C., Swisher-McClure, S., Dudley, J. T., Leeper, N. J., Shah, N. H. 2016; 34 (6): 566-571

    Abstract

    To test the association of androgen deprivation therapy (ADT) in the treatment of prostate cancer with subsequent Alzheimer's disease risk.We used a previously validated and implemented text-processing pipeline to analyze electronic medical record data in a retrospective cohort of patients at Stanford University and Mt. Sinai hospitals. Specifically, we extracted International Classification of Diseases-9th revision diagnosis and Current Procedural Terminology codes, medication lists, and positive-present mentions of drug and disease concepts from all clinical notes. We then tested the effect of ADT on risk of Alzheimer's disease using 1:5 propensity score-matched and traditional multivariable-adjusted Cox proportional hazards models. The duration of ADT use was also tested for association with Alzheimer's disease risk.There were 16,888 individuals with prostate cancer meeting all inclusion and exclusion criteria, with 2,397 (14.2%) receiving ADT during a median follow-up period of 2.7 years (interquartile range, 1.0-5.4 years). Propensity score-matched analysis (hazard ratio, 1.88; 95% CI, 1.10 to 3.20; P = .021) and traditional multivariable-adjusted Cox regression analysis (hazard ratio, 1.66; 95% CI, 1.05 to 2.64; P = .031) both supported a statistically significant association between ADT use and Alzheimer's disease risk. We also observed a statistically significant increased risk of Alzheimer's disease with increasing duration of ADT (P = .016).Our results support an association between the use of ADT in the treatment of prostate cancer and an increased risk of Alzheimer's disease in a general population cohort. This study demonstrates the utility of novel methods to analyze electronic medical record data to generate practice-based evidence.

    View details for DOI 10.1200/JCO.2015.63.6266

    View details for PubMedID 26644522

  • Reply. Gastroenterology Shah, N. H., Cooke, J. P., Leeper, N. J. 2016; 150 (2): 528-?

    View details for DOI 10.1053/j.gastro.2015.12.017

    View details for PubMedID 26721609

  • Proton pump inhibitors and vascular function: A prospective cross-over pilot study VASCULAR MEDICINE Ghebremariam, Y. T., Cooke, J. P., Khan, F., Thakker, R. N., Chang, P., Shah, N. H., Nead, K. T., Leeper, N. J. 2015; 20 (4): 309-316

    Abstract

    Proton pump inhibitors (PPIs) are commonly used drugs for the treatment of gastric reflux. Recent retrospective cohorts and large database studies have raised concern that the use of PPIs is associated with increased cardiovascular (CV) risk. However, there is no prospective clinical study evaluating whether the use of PPIs directly causes CV harm. We conducted a controlled, open-label, cross-over pilot study among 21 adults aged 18 and older who are healthy (n=11) or have established clinical cardiovascular disease (n=10). Study subjects were assigned to receive a PPI (Prevacid; 30 mg) or a placebo pill once daily for 4 weeks. After a 2-week washout period, participants were crossed over to receive the alternate treatment for the ensuing 4 weeks. Subjects underwent evaluation of vascular function (by the EndoPAT technique) and had plasma levels of asymmetric dimethylarginine (ADMA, an endogenous inhibitor of endothelial function previously implicated in PPI-mediated risk) measured prior to and after each treatment interval. We observed a marginal inverse correlation between the EndoPAT score and plasma levels of ADMA (r = -0.364). Subjects experienced a greater worsening in plasma ADMA levels while on PPI than on placebo, and this trend was more pronounced amongst those subjects with a history of vascular disease. However, these trends did not reach statistical significance, and PPI use was also not associated with an impairment in flow-mediated vasodilation during the course of this study. In conclusion, in this open-label, cross-over pilot study conducted among healthy subjects and coronary disease patients, PPI use did not significantly influence vascular endothelial function. Larger, long-term and blinded trials are needed to mechanistically explain the correlation between PPI use and adverse clinical outcomes, which has recently been reported in retrospective cohort studies.

    View details for DOI 10.1177/1358863X14568444

    View details for Web of Science ID 000359414300001

    View details for PubMedID 25835348

    View details for PubMedCentralID PMC4572842

  • Text-mining methods applied to clinical records support an association between androgen deprivation therapy and subsequent cardiometabolic disease Nead, K. T., Gaskin, G. L., Chester, C., Shah, N. H., Leeper, N. J. AMER ASSOC CANCER RESEARCH. 2015
  • Proton Pump Inhibitor Usage and the Risk of Myocardial Infarction in the General Population PLOS ONE Shah, N. H., LePendu, P., Bauer-Mehren, A., Ghebremariam, Y. T., Iyer, S. V., Marcus, J., Nead, K. T., Cooke, J. P., Leeper, N. J. 2015; 10 (6)

    Abstract

    Proton pump inhibitors (PPIs) have been associated with adverse clinical outcomes amongst clopidogrel users after an acute coronary syndrome. Recent pre-clinical results suggest that this risk might extend to subjects without any prior history of cardiovascular disease. We explore this potential risk in the general population via data-mining approaches.Using a novel approach for mining clinical data for pharmacovigilance, we queried over 16 million clinical documents on 2.9 million individuals to examine whether PPI usage was associated with cardiovascular risk in the general population.In multiple data sources, we found gastroesophageal reflux disease (GERD) patients exposed to PPIs to have a 1.16 fold increased association (95% CI 1.09-1.24) with myocardial infarction (MI). Survival analysis in a prospective cohort found a two-fold (HR = 2.00; 95% CI 1.07-3.78; P = 0.031) increase in association with cardiovascular mortality. We found that this association exists regardless of clopidogrel use. We also found that H2 blockers, an alternate treatment for GERD, were not associated with increased cardiovascular risk; had they been in place, such pharmacovigilance algorithms could have flagged this risk as early as the year 2000.Consistent with our pre-clinical findings that PPIs may adversely impact vascular function, our data-mining study supports the association of PPI exposure with risk for MI in the general population. These data provide an example of how a combination of experimental studies and data-mining approaches can be applied to prioritize drug safety signals for further investigation.

    View details for DOI 10.1371/journal.pone.0124653

    View details for Web of Science ID 000355979500007

    View details for PubMedID 26061035

    View details for PubMedCentralID PMC4462578

  • What Matters Most, Statin Intensity or Achieved LDL? - Evaluating Concordance of AHA/ACC Guidelines for Statin Use with Practice Outcomes at Stanford Hospital & Clinics Gyang, E., Shah, N., Leeper, N. SAGE PUBLICATIONS LTD. 2015: 295
  • Cyclin-Dependent Kinase Inhibitor 2B Regulates Transforming Growth Factor Beta 1 Mediated Smooth Muscle Cell Recruitment to Ischemic Blood Vessels Nanda, V., Downing, K., Kojima, Y., DiRenzo, D., Dalman, J., Connolly, A. J., Maegdefessel, L., Perisic, L., Dandona, S., Guo, L., Davis, H. R., Virmani, R., Spin, J., Leeper, N. SAGE PUBLICATIONS LTD. 2015: 274
  • Using clinical data text-mining analysis to examine the association between androgen deprivation therapy and depression. Nead, K. T., Gaskin, G. L., Chester, C., Leeper, N. J., Shah, N. H. AMER SOC CLINICAL ONCOLOGY. 2015
  • Improved Reclassification of Mortality Risk by Assessment of Physical Activity in Patients Referred for Exercise Testing AMERICAN JOURNAL OF MEDICINE Myers, J., Nead, K. T., Chang, P., Abella, J., Kokkinos, P., Leeper, N. J. 2015; 128 (4): 396-402

    Abstract

    Inability to meet minimal guidelines on physical activity is associated with poor health outcomes, but quantifying activity can be complex. We studied whether a simple question regarding participation in regular activity improves risk classification for all-cause mortality.Maximal exercise testing was performed in 6962 patients (mean age, 58.9 ± 11 years) for clinical reasons. Subjects also were assessed for participation in regular activity using a simple yes/no response to meeting minimal recommendations on activity. The incremental value of adding a simple physical activity assessment to clinical, demographic, and exercise test information to predict mortality was determined using Cox proportional hazards models, net reclassification improvement, and integrated discrimination index during a mean follow-up of 9.7 ± 4 years.Subjects who did not meet the minimal guidelines on activity had a lower exercise capacity (7.4 ± 4.3 vs 9.1 ± 3.6 metabolic equivalents, P < .0001) and a higher annual mortality rate (2.42% vs 1.71%, P < .001). Not meeting activity guidelines was associated with an age-adjusted 36% higher risk of mortality (hazard ratio, 1.36; 95% confidence interval, 1.22-1.51, P < .0001). Among clinical and exercise test variables, fitness had the highest C-index for predicting mortality (0.72, P < .001). The addition of physical activity classification to a model including traditional risk factors resulted in a net reclassification improvement of 22.8% (P < .001); adding fitness to the traditional risk factor model resulted in a net reclassification improvement of 43.5% (P < .001).The addition of a simple assessment of physical activity status significantly improves reclassification of risk for all-cause mortality among patients who are referred for exercise testing.

    View details for DOI 10.1016/j.amjmed.2014.10.061

    View details for Web of Science ID 000351365600029

    View details for PubMedID 25511076

  • Effect of physical activity assessment on prognostication for peripheral artery disease and mortality. Mayo Clinic proceedings Chang, P., Nead, K. T., Olin, J. W., Myers, J., Cooke, J. P., Leeper, N. J. 2015; 90 (3): 339-345

    Abstract

    To examine whether a simple question about the performance of regular vigorous activity is associated with peripheral artery disease (PAD) and mortality.A total of 1288 individuals undergoing nonemergency coronary angiography were assessed for participation in regular vigorous activity by questionnaire. Data on demographic characteristics, ankle-brachial indexes, and cardiovascular outcomes were prospectively collected.Compared with those who denied participation in regular vigorous activity, those who reported participation were less likely to have PAD (odds ratio, 0.58; 95% CI, 0.39-0.86), had higher ankle-brachial indexes, had better Walking Impairment Questionnaire scores (P<.001), and experienced reduced all-cause mortality rates (hazard ratio, 0.48; 95% CI, 0.31-0.74). When added to the Framingham Risk Score, the response improved the net reclassification index for all-cause (32.6%) and cardiovascular (32.0%) mortality.Among at-risk individuals, regular vigorous activity is associated with decreased PAD and all-cause mortality. Simple and readily available, a single yes/no query about participation in regular vigorous exercise could be used to improve risk stratification.

    View details for DOI 10.1016/j.mayocp.2014.12.016

    View details for PubMedID 25649965

  • MicroRNA Regulation of Vascular Smooth Muscle Function and Phenotype Early Career Committee Contribution ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Maegdefessel, L., Rayner, K. J., Leeper, N. J. 2015; 35 (1): 2-6

    View details for DOI 10.1161/ATVBAHA.114.304877

    View details for Web of Science ID 000346561100003

    View details for PubMedID 25520518

  • Therapeutic Potential of Modulating MicroRNA in Peripheral Artery Disease CURRENT VASCULAR PHARMACOLOGY Hamburg, N. M., Leeper, N. J. 2015; 13 (3): 316–23

    Abstract

    Peripheral artery disease (PAD) produces significant disability attributable to lower extremity ischemia. Limited treatment modalities exist to ameliorate clinical symptoms in patients with PAD. Growing evidence links microRNAs to key processes that govern disease expression in PAD including angiogenesis, endothelial function, inflammation, vascular regeneration, vascular smooth muscle cell function, restenosis, and mitochondrial function. MicroRNAs have been identified in circulation and may serve as novel biomarkers in PAD. This article reviews the potential contribution of microRNA to key pathways of disease development in PAD that may lead to microRNA-based diagnostic and therapeutic approaches.

    View details for DOI 10.2174/15701611113119990014

    View details for Web of Science ID 000357694900005

    View details for PubMedID 23713861

    View details for PubMedCentralID PMC4886469

  • Rationale and Design for PACE: Patients with Intermittent Claudication Injected with ALDH Bright Cells AMERICAN HEART JOURNAL Perin, E. C., Murphy, M., Cooke, J. P., Moye, L., Henry, T. D., Bettencourt, J., Gahremanpour, A., Leeper, N., Anderson, R. D., Hiatt, W. R., Lima, J. A., Venkatesh, B., Sayre, S. L., Vojvodic, R. W., Taylor, D. A., Ebert, R. F., Hirsch, A. T. 2014; 168 (5): 667-673

    Abstract

    Peripheral artery disease (PAD) is recognized as a public health issue because of its prevalence, functional limitations, and increased risk of systemic ischemic events. Current treatments for claudication, the primary symptom in patients with PAD, have limitations. Cells identified using cytosolic enzyme aldehyde dehydrogenase (ALDH) may benefit patients with severe PAD but has not been studied in patients with claudication. PACE is a randomized, double-blind, placebo-controlled clinical trial conducted by the Cardiovascular Cell Therapy Research Network to assess the safety and efficacy of autologous bone marrow-derived ALDH(br) cells delivered by direct intramuscular injections in 80 patients with symptom-limiting intermittent claudication. Eligible patients will have a significant stenosis or occlusion of infrainguinal arteries and a resting ankle-brachial index less than 0.90 and will be randomized 1:1 to cell or placebo treatment with a 1-year follow-up. The primary end points are the change in peak walking time and leg collateral arterial anatomy, calf muscle blood flow, and tissue perfusion as determined by magnetic resonance imaging at 6 months compared with baseline. The latter 3 measurements are new physiologic lower extremity tissue perfusion and PAD imaging-based end points that may help to quantify the biologic and mechanistic effects of cell therapy. This trial will collect important mechanistic and clinical information on the safety and efficacy of ALDH(br) cells in patients with claudication and provide valuable insight into the utility of advanced magnetic resonance imaging end points.

    View details for DOI 10.1016/j.ahj.2014.07.021

    View details for Web of Science ID 000344434300008

    View details for PubMedCentralID PMC4254580

  • Rationale and design for PACE: patients with intermittent claudication injected with ALDH bright cells. American heart journal Perin, E. C., Murphy, M., Cooke, J. P., Moyé, L., Henry, T. D., Bettencourt, J., Gahremanpour, A., Leeper, N., Anderson, R. D., Hiatt, W. R., Lima, J. A., Venkatesh, B., Sayre, S. L., Vojvodic, R. W., Taylor, D. A., Ebert, R. F., Hirsch, A. T. 2014; 168 (5): 667-673

    Abstract

    Peripheral artery disease (PAD) is recognized as a public health issue because of its prevalence, functional limitations, and increased risk of systemic ischemic events. Current treatments for claudication, the primary symptom in patients with PAD, have limitations. Cells identified using cytosolic enzyme aldehyde dehydrogenase (ALDH) may benefit patients with severe PAD but has not been studied in patients with claudication. PACE is a randomized, double-blind, placebo-controlled clinical trial conducted by the Cardiovascular Cell Therapy Research Network to assess the safety and efficacy of autologous bone marrow-derived ALDH(br) cells delivered by direct intramuscular injections in 80 patients with symptom-limiting intermittent claudication. Eligible patients will have a significant stenosis or occlusion of infrainguinal arteries and a resting ankle-brachial index less than 0.90 and will be randomized 1:1 to cell or placebo treatment with a 1-year follow-up. The primary end points are the change in peak walking time and leg collateral arterial anatomy, calf muscle blood flow, and tissue perfusion as determined by magnetic resonance imaging at 6 months compared with baseline. The latter 3 measurements are new physiologic lower extremity tissue perfusion and PAD imaging-based end points that may help to quantify the biologic and mechanistic effects of cell therapy. This trial will collect important mechanistic and clinical information on the safety and efficacy of ALDH(br) cells in patients with claudication and provide valuable insight into the utility of advanced magnetic resonance imaging end points.

    View details for DOI 10.1016/j.ahj.2014.07.021

    View details for PubMedID 25440794

  • Clinical and socioeconomic factors associated with unrecognized peripheral artery disease VASCULAR MEDICINE Chang, P., Nead, K. T., Olin, J. W., Cooke, J. P., Leeper, N. J. 2014; 19 (4): 289-296

    Abstract

    Peripheral artery disease (PAD) is a highly prevalent condition that frequently goes undetected and untreated. Socioeconomic factors associated with unrecognized PAD are not known. The ankle-brachial index (ABI) was calculated in 1656 study participants undergoing non-emergent coronary angiography with PAD defined as an ABI <0.9. Subjects were followed for mortality and cardiovascular outcomes. Compared to those without PAD, those with unrecognized PAD at enrollment were older, had higher rates of cardiovascular comorbidities, and had higher major adverse cardiovascular events (MACE) (p<0.03 for all). Among those enrolling without a reported history of PAD, there was a higher prevalence of PAD with decreasing income (p=0.004), education level (p<0.001), social isolation (p=0.027) and depression (p=0.034); 50% of these individuals reported symptoms suggestive of claudication. In conclusion, the prevalence of unrecognized PAD is high amongst a cohort of high-risk individuals referred for coronary angiography. A profile of lower socioeconomic status is associated with unrecognized PAD. These subjects will report symptoms suggestive of claudication and impaired walking ability when directly queried.

    View details for DOI 10.1177/1358863X14535475

    View details for Web of Science ID 000340161000006

  • Coronary heart disease-associated variation in TCF21 disrupts a miR-224 binding site and miRNA-mediated regulation. PLoS genetics Miller, C. L., Haas, U., Diaz, R., Leeper, N. J., Kundu, R. K., Patlolla, B., Assimes, T. L., Kaiser, F. J., Perisic, L., Hedin, U., Maegdefessel, L., Schunkert, H., Erdmann, J., Quertermous, T., Sczakiel, G. 2014; 10 (3)

    Abstract

    Genome-wide association studies (GWAS) have identified chromosomal loci that affect risk of coronary heart disease (CHD) independent of classical risk factors. One such association signal has been identified at 6q23.2 in both Caucasians and East Asians. The lead CHD-associated polymorphism in this region, rs12190287, resides in the 3' untranslated region (3'-UTR) of TCF21, a basic-helix-loop-helix transcription factor, and is predicted to alter the seed binding sequence for miR-224. Allelic imbalance studies in circulating leukocytes and human coronary artery smooth muscle cells (HCASMC) showed significant imbalance of the TCF21 transcript that correlated with genotype at rs12190287, consistent with this variant contributing to allele-specific expression differences. 3' UTR reporter gene transfection studies in HCASMC showed that the disease-associated C allele has reduced expression compared to the protective G allele. Kinetic analyses in vitro revealed faster RNA-RNA complex formation and greater binding of miR-224 with the TCF21 C allelic transcript. In addition, in vitro probing with Pb2+ and RNase T1 revealed structural differences between the TCF21 variants in proximity of the rs12190287 variant, which are predicted to provide greater access to the C allele for miR-224 binding. miR-224 and TCF21 expression levels were anti-correlated in HCASMC, and miR-224 modulates the transcriptional response of TCF21 to transforming growth factor-β (TGF-β) and platelet derived growth factor (PDGF) signaling in an allele-specific manner. Lastly, miR-224 and TCF21 were localized in human coronary artery lesions and anti-correlated during atherosclerosis. Together, these data suggest that miR-224 interaction with the TCF21 transcript contributes to allelic imbalance of this gene, thus partly explaining the genetic risk for coronary heart disease associated at 6q23.2. These studies implicating rs12190287 in the miRNA-dependent regulation of TCF21, in conjunction with previous studies showing that this variant modulates transcriptional regulation through activator protein 1 (AP-1), suggests a unique bimodal level of complexity previously unreported for disease-associated variants.

    View details for DOI 10.1371/journal.pgen.1004263

    View details for PubMedID 24676100

    View details for PubMedCentralID PMC3967965

  • Coronary heart disease-associated variation in TCF21 disrupts a miR-224 binding site and miRNA-mediated regulation. PLoS genetics Miller, C. L., Haas, U., Diaz, R., Leeper, N. J., Kundu, R. K., Patlolla, B., Assimes, T. L., Kaiser, F. J., Perisic, L., Hedin, U., Maegdefessel, L., Schunkert, H., Erdmann, J., Quertermous, T., Sczakiel, G. 2014; 10 (3)

    View details for DOI 10.1371/journal.pgen.1004263

    View details for PubMedID 24676100

  • The combination of 9p21.3 genotype and biomarker profile improves a peripheral artery disease risk prediction model. Vascular medicine Downing, K. P., Nead, K. T., Kojima, Y., Assimes, T., Maegdefessel, L., Quertermous, T., Cooke, J. P., Leeper, N. J. 2014; 19 (1): 3-8

    Abstract

    Peripheral artery disease (PAD) is a highly morbid condition affecting more than 8 million Americans. Frequently, PAD patients are unrecognized and therefore do not receive appropriate therapies. Therefore, new methods to identify PAD have been pursued, but have thus far had only modest success. Here we describe a new approach combining genomic and metabolic information to enhance the diagnosis of PAD. We measured the genotype of the chromosome 9p21 cardiovascular-risk polymorphism rs10757269 as well as the biomarkers C-reactive protein, cystatin C, β2-microglobulin, and plasma glucose in a study population of 393 patients undergoing coronary angiography. The rs10757269 allele was associated with PAD status (ankle-brachial index < 0.9) independent of biomarkers and traditional cardiovascular risk factors (odds ratio=1.92; 95% confidence interval, 1.29-2.85). Importantly, compared to a previously validated risk factor-based PAD prediction model, the addition of biomarkers and rs10757269 significantly and incrementally improved PAD risk prediction as assessed by the net reclassification index (NRI=33.5%; p=0.001) and integrated discrimination improvement (IDI=0.016; p=0.017). In conclusion, a model including a panel of biomarkers, which includes both genomic information (which is reflective of heritable risk) and metabolic information (which integrates environmental exposures), predicts the presence or absence of PAD better than established risk models, suggesting clinical utility for the diagnosis of PAD.

    View details for DOI 10.1177/1358863X13514791

    View details for PubMedID 24323119

  • Self-reported history of childhood smoking is associated with an increased risk for peripheral arterial disease independent of lifetime smoking burden. PloS one Priest, J. R., Nead, K. T., Wehner, M. R., Cooke, J. P., Leeper, N. J. 2014; 9 (2)

    Abstract

    Atherosclerotic disorders are well known to be associated with obesity, lipid profile, smoking, hypertension and other medical comorbidities, and large cohort studies have explored the childhood correlates to these adult risk factors. However, there has been little investigation into the childhood risk factors for peripheral arterial disease (PAD). We endeavored to better understand the role of smoking in childhood in the risk for PAD in a well described cohort of 1,537 adults at high risk for cardiovascular disease. In a multivariate regression model, we observed an increased risk of PAD among those who reported a history of smoking during childhood (OR = 2.86; 95% CI, 1.99-4.11; P<0.001), which remained statistically significant after controlling for lifetime smoking burden (OR = 1.55; 95% CI, 1.00-2.41; P = 0.049). Our novel observation of disproportionate risk of PAD conferred by a history of childhood smoking may reflect an unrecognized biological mechanism such as a unique susceptibility to vascular injury or an unaccounted for covariate such as secondhand smoke exposure in childhood. This observation suggests further investigation is required into the pathophysiology of smoking in the developing vasculature and the need for detailed clinical data about patterns of childhood smoking and smoke exposure.

    View details for DOI 10.1371/journal.pone.0088972

    View details for PubMedID 24558458

  • Clinical and socioeconomic factors associated with unrecognized peripheral artery disease. Vascular medicine (London, England) Chang, P., Nead, K. T., Olin, J. W., Cooke, J. P., Leeper, N. J. 2014; 19 (4): 289–96

    Abstract

    Peripheral artery disease (PAD) is a highly prevalent condition that frequently goes undetected and untreated. Socioeconomic factors associated with unrecognized PAD are not known. The ankle-brachial index (ABI) was calculated in 1656 study participants undergoing non-emergent coronary angiography with PAD defined as an ABI <0.9. Subjects were followed for mortality and cardiovascular outcomes. Compared to those without PAD, those with unrecognized PAD at enrollment were older, had higher rates of cardiovascular comorbidities, and had higher major adverse cardiovascular events (MACE) (p<0.03 for all). Among those enrolling without a reported history of PAD, there was a higher prevalence of PAD with decreasing income (p=0.004), education level (p<0.001), social isolation (p=0.027) and depression (p=0.034); 50% of these individuals reported symptoms suggestive of claudication. In conclusion, the prevalence of unrecognized PAD is high amongst a cohort of high-risk individuals referred for coronary angiography. A profile of lower socioeconomic status is associated with unrecognized PAD. These subjects will report symptoms suggestive of claudication and impaired walking ability when directly queried.

    View details for PubMedID 24872403

  • Association of lower extremity performance with cardiovascular and all-cause mortality in patients with peripheral artery disease: a systematic review and meta-analysis. Journal of the American Heart Association Morris, D. R., Rodriguez, A. J., Moxon, J. V., Cunningham, M. A., McDermott, M. M., Myers, J., Leeper, N. J., Jones, R. E., Golledge, J. 2014; 3 (4)

    Abstract

    Peripheral artery disease (PAD) is associated with impaired mobility and a high rate of mortality. The aim of this systematic review was to investigate whether reduced lower extremity performance was associated with an increased incidence of cardiovascular and all-cause mortality in people with PAD.A systematic search of the MEDLINE, EMBASE, SCOPUS, Web of Science, and Cochrane Library databases was conducted. Studies assessing the association between measures of lower extremity performance and cardiovascular or all-cause mortality in PAD patients were included. A meta-analysis was conducted combining data from commonly assessed performance tests. The 10 identified studies assessed lower extremity performance by strength tests, treadmill walking performance, 6-minute walk, walking velocity, and walking impairment questionnaire (WIQ). A meta-analysis revealed that shorter maximum walking distance was associated with increased 5-year cardiovascular (unadjusted RR=2.54, 95% CI 1.86 to 3.47, P<10(-5), n=1577, fixed effects) and all-cause mortality (unadjusted RR=2.23 95% CI 1.85 to 2.69, P<10(-5), n=1710, fixed effects). Slower 4-metre walking velocity, a lower WIQ stair-climbing score, and poor hip extension, knee flexion, and plantar flexion strength were also associated with increased mortality. No significant associations were found for hip flexion strength, WIQ distance score, or WIQ speed score with mortality.A number of lower extremity performance measures are prognostic markers for mortality in PAD and may be useful clinical tools for identifying patients at higher risk of death. Further studies are needed to determine whether interventions that improve measures of lower extremity performance reduce mortality.

    View details for DOI 10.1161/JAHA.114.001105

    View details for PubMedID 25122666

  • Self-reported history of childhood smoking is associated with an increased risk for peripheral arterial disease independent of lifetime smoking burden. PloS one Priest, J. R., Nead, K. T., Wehner, M. R., Cooke, J. P., Leeper, N. J. 2014; 9 (2)

    View details for DOI 10.1371/journal.pone.0088972

    View details for PubMedID 24558458

  • Socioeconomic Barriers to the Diagnosis of Peripheral Arterial Disease Chang, P., Nead, K. T., Thakker, R., Cooke, J. P., Olin, J. W., Leeper, N. J. LIPPINCOTT WILLIAMS & WILKINS. 2013
  • Disease-Related Growth Factor and Embryonic Signaling Pathways Modulate an Enhancer of TCF21 Expression at the 6q23.2 Coronary Heart Disease Locus PLOS GENETICS Miller, C. L., Anderson, D. R., Kundu, R. K., Raiesdana, A., Nuernberg, S. T., Diaz, R., Cheng, K., Leeper, N. J., Chen, C., Chang, I., Schadt, E. E., Hsiung, C. A., Assimes, T. L., Quertermous, T. 2013; 9 (7)

    Abstract

    Coronary heart disease (CHD) is the leading cause of mortality in both developed and developing countries worldwide. Genome-wide association studies (GWAS) have now identified 46 independent susceptibility loci for CHD, however, the biological and disease-relevant mechanisms for these associations remain elusive. The large-scale meta-analysis of GWAS recently identified in Caucasians a CHD-associated locus at chromosome 6q23.2, a region containing the transcription factor TCF21 gene. TCF21 (Capsulin/Pod1/Epicardin) is a member of the basic-helix-loop-helix (bHLH) transcription factor family, and regulates cell fate decisions and differentiation in the developing coronary vasculature. Herein, we characterize a cis-regulatory mechanism by which the lead polymorphism rs12190287 disrupts an atypical activator protein 1 (AP-1) element, as demonstrated by allele-specific transcriptional regulation, transcription factor binding, and chromatin organization, leading to altered TCF21 expression. Further, this element is shown to mediate signaling through platelet-derived growth factor receptor beta (PDGFR-β) and Wilms tumor 1 (WT1) pathways. A second disease allele identified in East Asians also appears to disrupt an AP-1-like element. Thus, both disease-related growth factor and embryonic signaling pathways may regulate CHD risk through two independent alleles at TCF21.

    View details for DOI 10.1371/journal.pgen.1003652

    View details for Web of Science ID 000322321100049

    View details for PubMedID 23874238

    View details for PubMedCentralID PMC3715442

  • A hybrid genomic and proteomic biomarker panel accurately predicts peripheral arterial disease status Nead, K. T., Putnam, K., Cooke, J. P., Olin, J. W., Leeper, N. J. SAGE PUBLICATIONS LTD. 2013: 165–65
  • Walking impairment questionnaire improves mortality risk prediction models in a high-risk cohort independent of peripheral arterial disease status. Circulation. Cardiovascular quality and outcomes Nead, K. T., Zhou, M., Caceres, R. D., Olin, J. W., Cooke, J. P., Leeper, N. J. 2013; 6 (3): 255-261

    Abstract

    Background- The Walking Impairment Questionnaire (WIQ) is a subjective measure of patient-reported walking performance developed for peripheral arterial disease. The purpose of this study is to examine whether this simple tool can improve the predictive capacity of established risk models and whether the WIQ can be used in patients without peripheral arterial disease. Methods and Results- At baseline we assessed the walking distance, stair-climbing, and walking speed WIQ category scores among individuals who were undergoing coronary angiography. During a median follow-up of 5.0 years, there were 172 mortalities among 1417 study participants. Adjusted Cox proportional hazards models showed that all 3 WIQ categories independently predicted future all-cause and cardiovascular mortality, including among individuals without peripheral arterial disease (P<0.001). Compared with the cardiovascular risk factors model, we observed significantly increased risk discrimination with a C-index of 0.741 (change in C-index, 0.040; 95% confidence interval, 0.011-0.068) and 0.832 (change in C-index, 0.080; 95% confidence interval, 0.034-0.126) for all-cause and cardiovascular mortality, respectively. Examination of risk reclassification using the net reclassification improvement index showed a 48.4% (P<0.001) improvement for all-cause mortality and a 77.4% (P<0.001) improvement for cardiovascular mortality compared with the cardiovascular risk factors model. Conclusions- All 3 WIQ categories independently predicted future all-cause and cardiovascular mortality. Importantly, we found that this subjective measure of walking ability could be extended to patients without peripheral arterial disease. The addition of the WIQ scores to established cardiovascular risk models significantly improved risk discrimination and reclassification, suggesting broad clinical use for this simple, inexpensive test.

    View details for DOI 10.1161/CIRCOUTCOMES.111.000070

    View details for PubMedID 23633217

  • Usefulness of the Addition of Beta-2-Microglobulin, Cystatin C and C-Reactive Protein to an Established Risk Factors Model to Improve Mortality Risk Prediction in Patients Undergoing Coronary Angiography AMERICAN JOURNAL OF CARDIOLOGY Nead, K. T., Zhou, M. J., Caceres, R. D., Sharp, S. J., Wehner, M. R., Olin, J. W., Cooke, J. P., Leeper, N. J. 2013; 111 (6): 851-856

    Abstract

    Evidence-based therapies are available to reduce the risk for death from cardiovascular disease, yet many patients go untreated. Novel methods are needed to identify those at highest risk for cardiovascular death. In this study, the biomarkers β2-microglobulin, cystatin C, and C-reactive protein were measured at baseline in a cohort of participants who underwent coronary angiography. Adjusted Cox proportional-hazards models were used to determine whether the biomarkers predicted all-cause and cardiovascular mortality. Additionally, improvements in risk reclassification and discrimination were evaluated by calculating the net reclassification improvement, C-index, and integrated discrimination improvement with the addition of the biomarkers to a baseline model of risk factors for cardiovascular disease and death. During a median follow-up period of 5.6 years, there were 78 deaths among 470 participants. All biomarkers independently predicted future all-cause and cardiovascular mortality. A significant improvement in risk reclassification was observed for all-cause (net reclassification improvement 35.8%, p = 0.004) and cardiovascular (net reclassification improvement 61.9%, p = 0.008) mortality compared to the baseline risk factors model. Additionally, there was significantly increased risk discrimination with C-indexes of 0.777 (change in C-index 0.057, 95% confidence interval 0.016 to 0.097) and 0.826 (change in C-index 0.071, 95% confidence interval 0.010 to 0.133) for all-cause and cardiovascular mortality, respectively. Improvements in risk discrimination were further supported using the integrated discrimination improvement index. In conclusion, this study provides evidence that β2-microglobulin, cystatin C, and C-reactive protein predict mortality and improve risk reclassification and discrimination for a high-risk cohort of patients who undergo coronary angiography.

    View details for DOI 10.1016/j.amjcard.2012.11.055

    View details for Web of Science ID 000316537700013

    View details for PubMedID 23290308

    View details for PubMedCentralID PMC3594484

  • AN ALTERNATIVE ANKLE-BRACHIAL INDEX METHOD IDENTIFIES INDIVIDUALS AT HIGH-RISK FOR CARDIOVASCULAR MORTALITY THAT ARE CURRENTLY OVERLOOKED 62nd Annual Scientific Session of the American-College-of-Cardiology Nead, K. T., Cooke, J. P., Leeper, N. J. ELSEVIER SCIENCE INC. 2013: E2124–E2124
  • Exercise capacity is the strongest predictor of mortality in patients with peripheral arterial disease JOURNAL OF VASCULAR SURGERY Leeper, N. J., Myers, J., Zhou, M., Nead, K. T., Syed, A., Kojima, Y., Caceres, R. D., Cooke, J. P. 2013; 57 (3): 728-733

    Abstract

    The objective of this study was to assess the predictive value of clinical and exercise test variables in patients with peripheral arterial disease (PAD).A customized symptom-limited ramp treadmill protocol was used to assess 725 PAD patients referred for exercise testing at the Palo Alto Veterans Hospital between 1997 and 2011. Detailed clinical and exercise test data were collected at baseline, and patients were followed up for a mean of 11.3 ± 6.3 years.During follow-up, there were 364 deaths. Baseline exercise capacity was 7.0 ± 2.6 metabolic equivalents (METs) among survivors and 5.5 ± 2.4 METs in those who died (P < .001). Although several physiologic parameters differed between survivors and nonsurvivors, age-adjusted Cox regression revealed that exercise capacity was the strongest independent predictor of death. Each additional MET achieved was associated with age-adjusted 18% and 20% reductions in all-cause and cardiovascular mortality, respectively (P < .001 for both). This variable surpassed all classical risk factors (including smoking and history of congestive heart failure) and all measured exercise test responses (including symptoms and electrocardiograph abnormalities).Among PAD patients, reduced exercise capacity is the most powerful harbinger of long-term mortality. This factor has predictive power beyond traditional risk factors and confirms the critical importance of fitness in this cohort.

    View details for DOI 10.1016/j.jvs.2012.07.051

    View details for Web of Science ID 000315944400019

    View details for PubMedID 23044259

    View details for PubMedCentralID PMC3543469

  • Disease-related growth factor and embryonic signaling pathways modulate an enhancer of TCF21 expression at the 6q23.2 coronary heart disease locus. PLoS genetics Miller, C. L., Anderson, D. R., Kundu, R. K., Raiesdana, A., Nürnberg, S. T., Diaz, R., Cheng, K., Leeper, N. J., Chen, C., Chang, I., Schadt, E. E., Hsiung, C. A., Assimes, T. L., Quertermous, T. 2013; 9 (7)

    Abstract

    Coronary heart disease (CHD) is the leading cause of mortality in both developed and developing countries worldwide. Genome-wide association studies (GWAS) have now identified 46 independent susceptibility loci for CHD, however, the biological and disease-relevant mechanisms for these associations remain elusive. The large-scale meta-analysis of GWAS recently identified in Caucasians a CHD-associated locus at chromosome 6q23.2, a region containing the transcription factor TCF21 gene. TCF21 (Capsulin/Pod1/Epicardin) is a member of the basic-helix-loop-helix (bHLH) transcription factor family, and regulates cell fate decisions and differentiation in the developing coronary vasculature. Herein, we characterize a cis-regulatory mechanism by which the lead polymorphism rs12190287 disrupts an atypical activator protein 1 (AP-1) element, as demonstrated by allele-specific transcriptional regulation, transcription factor binding, and chromatin organization, leading to altered TCF21 expression. Further, this element is shown to mediate signaling through platelet-derived growth factor receptor beta (PDGFR-β) and Wilms tumor 1 (WT1) pathways. A second disease allele identified in East Asians also appears to disrupt an AP-1-like element. Thus, both disease-related growth factor and embryonic signaling pathways may regulate CHD risk through two independent alleles at TCF21.

    View details for DOI 10.1371/journal.pgen.1003652

    View details for PubMedID 23874238

    View details for PubMedCentralID PMC3715442

  • Practice-based evidence: profiling the safety of cilostazol by text-mining of clinical notes. PloS one Leeper, N. J., Bauer-Mehren, A., Iyer, S. V., LePendu, P., Olson, C., Shah, N. H. 2013; 8 (5)

    View details for DOI 10.1371/journal.pone.0063499

    View details for PubMedID 23717437

  • Loss of CDKN2B Promotes p53-Dependent Smooth Muscle Cell Apoptosis and Aneurysm Formation ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Leeper, N. J., Raiesdana, A., Kojima, Y., Kundu, R. K., Cheng, H., Maegdefessel, L., Toh, R., Ahn, G., Ali, Z. A., Anderson, D. R., Miller, C. L., Roberts, S. C., Spin, J. M., de Almeida, P. E., Wu, J. C., Xu, B., Cheng, K., Quertermous, M., Kundu, S., Kortekaas, K. E., Berzin, E., Downing, K. P., Dalman, R. L., Tsao, P. S., Schadt, E. E., Owens, G. K., Quertermous, T. 2013; 33 (1): E1-?

    Abstract

    Genomewide association studies have implicated allelic variation at 9p21.3 in multiple forms of vascular disease, including atherosclerotic coronary heart disease and abdominal aortic aneurysm. As for other genes at 9p21.3, human expression quantitative trait locus studies have associated expression of the tumor suppressor gene CDKN2B with the risk haplotype, but its potential role in vascular pathobiology remains unclear.Here we used vascular injury models and found that Cdkn2b knockout mice displayed the expected increase in proliferation after injury, but developed reduced neointimal lesions and larger aortic aneurysms. In situ and in vitro studies suggested that these effects were attributable to increased smooth muscle cell apoptosis. Adoptive bone marrow transplant studies confirmed that the observed effects of Cdkn2b were mediated through intrinsic vascular cells and were not dependent on bone marrow-derived inflammatory cells. Mechanistic studies suggested that the observed increase in apoptosis was attributable to a reduction in MDM2 and an increase in p53 signaling, possibly due in part to compensation by other genes at the 9p21.3 locus. Dual inhibition of both Cdkn2b and p53 led to a reversal of the vascular phenotype in each model.These results suggest that reduced CDKN2B expression and increased smooth muscle cell apoptosis may be one mechanism underlying the 9p21.3 association with aneurysmal disease.

    View details for DOI 10.1161/ATVBAHA.112.300399

    View details for Web of Science ID 000312392500001

    View details for PubMedID 23162013

    View details for PubMedCentralID PMC3569043

  • Network analysis of unstructured EHR data for clinical research. AMIA Summits on Translational Science proceedings AMIA Summit on Translational Science Bauer-Mehren, A., LePendu, P., Iyer, S. V., Harpaz, R., Leeper, N. J., Shah, N. H. 2013; 2013: 14-18

    Abstract

    In biomedical research, network analysis provides a conceptual framework for interpreting data from high-throughput experiments. For example, protein-protein interaction networks have been successfully used to identify candidate disease genes. Recently, advances in clinical text processing and the increasing availability of clinical data have enabled analogous analyses on data from electronic medical records. We constructed networks of diseases, drugs, medical devices and procedures using concepts recognized in clinical notes from the Stanford clinical data warehouse. We demonstrate the use of the resulting networks for clinical research informatics in two ways-cohort construction and outcomes analysis-by examining the safety of cilostazol in peripheral artery disease patients as a use case. We show that the network-based approaches can be used for constructing patient cohorts as well as for analyzing differences in outcomes by comparing with standard methods, and discuss the advantages offered by network-based approaches.

    View details for PubMedID 24303229

  • Practice-based evidence: profiling the safety of cilostazol by text-mining of clinical notes. PloS one Leeper, N. J., Bauer-Mehren, A., Iyer, S. V., LePendu, P., Olson, C., Shah, N. H. 2013; 8 (5)

    Abstract

    Peripheral arterial disease (PAD) is a growing problem with few available therapies. Cilostazol is the only FDA-approved medication with a class I indication for intermittent claudication, but carries a black box warning due to concerns for increased cardiovascular mortality. To assess the validity of this black box warning, we employed a novel text-analytics pipeline to quantify the adverse events associated with Cilostazol use in a clinical setting, including patients with congestive heart failure (CHF).We analyzed the electronic medical records of 1.8 million subjects from the Stanford clinical data warehouse spanning 18 years using a novel text-mining/statistical analytics pipeline. We identified 232 PAD patients taking Cilostazol and created a control group of 1,160 PAD patients not taking this drug using 1∶5 propensity-score matching. Over a mean follow up of 4.2 years, we observed no association between Cilostazol use and any major adverse cardiovascular event including stroke (OR = 1.13, CI [0.82, 1.55]), myocardial infarction (OR = 1.00, CI [0.71, 1.39]), or death (OR = 0.86, CI [0.63, 1.18]). Cilostazol was not associated with an increase in any arrhythmic complication. We also identified a subset of CHF patients who were prescribed Cilostazol despite its black box warning, and found that it did not increase mortality in this high-risk group of patients.This proof of principle study shows the potential of text-analytics to mine clinical data warehouses to uncover 'natural experiments' such as the use of Cilostazol in CHF patients. We envision this method will have broad applications for examining difficult to test clinical hypotheses and to aid in post-marketing drug safety surveillance. Moreover, our observations argue for a prospective study to examine the validity of a drug safety warning that may be unnecessarily limiting the use of an efficacious therapy.

    View details for DOI 10.1371/journal.pone.0063499

    View details for PubMedID 23717437

    View details for PubMedCentralID PMC3662653

  • Exercise capacity is the strongest predictor of mortality in patients with peripheral arterial disease Zhou, M., Leeper, N. J., Nead, K. T., Syed, A., Abella, J., Kojima, Y., Panchal, S. N., Cooke, J. P., Myers, J. SAGE PUBLICATIONS LTD. 2012: 204–5
  • The Effect of Angiotensin-Converting Enzyme Inhibitors and Statins on the Progression of Aortic Sclerosis and Mortality JOURNAL OF HEART VALVE DISEASE Ardehali, R., Leeper, N. J., Wilson, A. M., Heidenreich, P. A. 2012; 21 (3): 337-343

    Abstract

    Although aortic sclerosis has been associated with an increase in adverse cardiovascular outcomes, no proven therapy has been shown to slow its progression to overt aortic stenosis (AS). Thus, the hypothesis was assessed that treatment with angiotensin-converting enzyme inhibitors (ACE-Is), angiotensin receptor blockers (ARBs) or statins may be associated with an improvement in the clinical outcome of these patients.A total of 4,105 patients with evidence of aortic sclerosis seen on transthoracic echocardiography (defined as thickening or calcification with a mean valve gradient < or = 15 mmHg) was identified. Patients with a sclerotic valve who were treated with ACE-Is/ARBs or statins were followed for a mean period of 1,078 +/- 615 days. After adjustment for the propensity to receive ACE-Is/ARBs or statins, mortality, hemodynamic progression to AS, hospitalization for ischemic heart disease (IHD), and congestive heart failure (CHF) were assessed and related to the medical treatment.At baseline, patients with aortic sclerosis who were treated with an ACE-I/ARB or a statin suffered significantly more from comorbidities such as IHD, CHF, hypertension, diabetes, and peripheral arterial disease, when compared to subjects with sclerotic valves not treated with these drugs. After adjustment for confounding factors, treatment with statins was associated with a significant reduction in mortality (odds ratio [OR] 0.73, 95% CI 0.56-0.98, p = 0.001), admission for IHD (OR 0.81, 95% CI 0.66-0.99, p = 0.03), admission for CHF (OR 0.68, 95% CI 0.55-0.85, p = 0.01) and progression to AS (OR 0.64, 95% CI 0.42-0.97, p = 0.03). While ACE-I treatment resulted in a significant reduction in admission for IHD (OR 0.80, 95% CI 0.65-0.98, p = 0.03) and CHF (OR 0.76, 95% CI 0.62-0.94, p = 0.01), the beneficial trend towards reduced mortality and delayed progression to AS was not significant.Treatment of this patient population with statins led to a significant reduction in mortality and also slowed the progression to AS--an effect that was not statistically significant with ACE-I treatment.

    View details for Web of Science ID 000306675500011

    View details for PubMedID 22808835

  • Network Analysis Identifies the Orphan Receptor Tyrosine Kinase Ros1 as a Determinant of Glutathione Peroxidase-1 Mediated Vascular Remodeling Scientific Sessions of the American-Heart-Association/Resuscitation Science Symposium Ali, Z. A., Perez, V. D., Raiesdana, A., Leeper, N. J., Pan, S., Qu, X., Ali, A., Haghighat, R., Kato, K., Channon, K. M., Rabinovitch, M., Quertermous, T., Ashley, E. A. LIPPINCOTT WILLIAMS & WILKINS. 2011
  • Microrna-21 Regulates Expansion of Abdominal Aortic Aneurysms Through the PTEN/PI3K/AKT Pathway Scientific Sessions of the American-Heart-Association/Resuscitation Science Symposium Maegdefessel, L., Azuma, J., Deng, A., Toh, R. M., Merk, D. R., Raiesdana, A., Leeper, N. J., Spin, J. M., Tsao, P. S. LIPPINCOTT WILLIAMS & WILKINS. 2011
  • Two Decades of Progress in Vascular Medicine AMERICAN JOURNAL OF MEDICINE Leeper, N. J., Lee, J. T., Cooke, J. P. 2011; 124 (9): 791-792

    View details for DOI 10.1016/j.amjmed.2011.03.017

    View details for PubMedID 21683936

  • CDKN2B Regulates Cell Fate Decisions in Human Vascular Smooth Muscle Cells Leeper, N. J., Raiesdana, A., Cheng, H., Kundu, R. K., Kojima, Y., Cheng, K., Schadt, E., Quertermous, T. LIPPINCOTT WILLIAMS & WILKINS. 2010
  • The Role of CDKN2B in Vascular Disease Cheng, H. G., Leeper, N. J., Raisedana, A., Kundu, R., Kojima, Y., Quertermous, T. LIPPINCOTT WILLIAMS & WILKINS. 2010
  • Microarray Analysis Identifies miRNA-26a as a Regulator of Vascular Smooth Muscle Cell Phenotypic Modulation Scientific Sessions on Arteriosclerosis, Thrombosis and Vascular Biology Leeper, N. J., Raiesdana, A., Kojima, Y., Chun, H. J., Azuma, J., Kundu, R. K., Quertermous, T., Tsao, P. S., Spin, J. M. LIPPINCOTT WILLIAMS & WILKINS. 2010: E244–E244
  • Upregulation of the apelin-APJ pathway promotes neointima formation in the carotid ligation model in mouse CARDIOVASCULAR RESEARCH Kojima, Y., Kundu, R. K., Cox, C. M., Leeper, N. J., Anderson, J. A., Chun, H. J., Ali, Z. A., Ashley, E. A., Krieg, P. A., Quertermous, T. 2010; 87 (1): 156-165

    Abstract

    To investigate apelin-APJ (angiotensin receptor-like 1) signalling in vascular remodelling, we have examined the pathophysiological response to carotid ligation in apelin knockout mice.Apelin null animals compared with wild-type mice had significantly decreased neointimal lesion area (1.17 +/- 0.17 vs. 3.33 +/- 1.04 x 10(4) microm(2), P < 0.05) and intima/media ratio (0.81 +/- 0.23 vs. 1.49 +/- 0.44, P < 0.05), averaged over four sites 0.5-2 mm from the ligation. Exogenous apelin infusion rescued the apelin-KO phenotype, promoting neointima formation in the null animals. Apelin null animals showed decreased smooth muscle positive area in the neointima (82.3 +/- 2.4 vs. 63.9 +/- 8.4, P < 0.05), and a smaller percentage BrdU positive cells in the neointima and media (11.06 +/- 1.00 vs. 6.53 +/- 0.86, P < 0.05). Apelin mRNA expression increased initially (5.2-fold, P < 0.01) followed by increased apelin receptor expression (10.1-fold, P < 0.05) in the ligated artery. Cytochemistry studies localized apelin expression to luminal endothelial cells and apelin receptor upregulation to smooth muscle cells (SMC) in the media and neointima. In vitro experiments with cultured rat aortic SMC revealed that apelin stimulation increased migration. In contrast to the increased expression of apelin and apelin receptor in carotid remodelling, expression was not upregulated in the apoE high fat model, and correlated with the known disease-inhibitory effect in this model.These data suggest that increased apelin receptor expression by SMC provides a paracrine pathway in injured vessels that allows endothelial-derived apelin to stimulate their division and migration into the neointima.

    View details for DOI 10.1093/cvr/cvq052

    View details for PubMedID 20176814

  • Apelin Modulates Adipocyte and Inflammatory Cell Processes to Inhibit Atherosclerosis Kojima, Y., Kundu, R., Leeper, N. J., Chun, H. J., Quertermous, T. LIPPINCOTT WILLIAMS & WILKINS. 2009: S1064
  • Endogenous regulation of cardiovascular function by apelin-APJ AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Charo, D. N., Ho, M., Fajardo, G., Kawana, M., Kundu, R. K., Sheikh, A. Y., Finsterbach, T. P., Leeper, N. J., Ernst, K. V., Chen, M. M., Ho, Y. D., Chun, H. J., Bernstein, D., Ashley, E. A., Quertermous, T. 2009; 297 (5): H1904-H1913

    Abstract

    Studies have shown significant cardiovascular effects of exogenous apelin administration, including the potent activation of cardiac contraction. However, the role of the endogenous apelin-APJ pathway is less clear. To study the loss of endogenous apelin-APJ signaling, we generated mice lacking either the ligand (apelin) or the receptor (APJ). Apelin-deficient mice were viable, fertile, and showed normal development. In contrast, APJ-deficient mice were not born in the expected Mendelian ratio, and many showed cardiovascular developmental defects. Under basal conditions, both apelin and APJ null mice that survived to adulthood manifested modest decrements in contractile function. However, with exercise stress both mutant lines demonstrated consistent and striking decreases in exercise capacity. To explain these findings, we explored the role of autocrine signaling in vitro using field stimulation of isolated left ventricular cardiomyocytes lacking either apelin or APJ. Both groups manifested less sarcomeric shortening and impaired velocity of contraction and relaxation with no difference in calcium transient. Taken together, these results demonstrate that endogenous apelin-APJ signaling plays a modest role in maintaining basal cardiac function in adult mice with a more substantive role during conditions of stress. In addition, an autocrine pathway seems to exist in myocardial cells, the ablation of which reduces cellular contraction without change in calcium transient. Finally, differences in the developmental phenotype between apelin and APJ null mice suggest the possibility of undiscovered APJ ligands or ligand-independent effects of APJ.

    View details for DOI 10.1152/ajpheart.00686.2009

    View details for Web of Science ID 000271143400045

    View details for PubMedID 19767528

    View details for PubMedCentralID PMC2781363

  • Apelin Regulates Vascular Remodeling In The Mouse Carotid Artery Ligation Model Kojima, Y., Kundu, R., Leeper, N. J., Anderson, J., Quertermous, T. LIPPINCOTT WILLIAMS & WILKINS. 2008: S574
  • Apelin Prevents Aortic Aneurysm Formation by Inhibiting Macrophage Inflammation and Infiltration Leeper, N. J., Tedesco, M. M., Kojima, Y., Schultz, G., Ho, M. Y., Kundu, R. K., Anderson, J. P., Tsao, P. S., Dolman, R. L., Quedermous, T. LIPPINCOTT WILLIAMS & WILKINS. 2008: S451
  • Atherosclerosis Development is Increased in Apelin/Apoe Double Knockout Mice Kojima, Y., Kundu, R., Leeper, N. J., Quortermous, T. LIPPINCOTT WILLIAMS & WILKINS. 2008: S481
  • Response to letter regarding article, "Statin use in patients with extremely low low-density lipoprotein levels is associated with improved survival" CIRCULATION Leeper, N. J., Ardehali, R., DeGoma, E. M., Heidenreich, P. A. 2008; 117 (9): E175-E175
  • Clinical significance of high-density lipoprotein cholesterol in patients with low low-density lipoprotein cholesterol JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY deGoma, E. M., Leeper, N. J., Heidenreich, P. A. 2008; 51 (1): 49-55

    Abstract

    We sought to evaluate the significance of high-density lipoprotein cholesterol (HDL-C) in the context of low low-density lipoprotein cholesterol (LDL-C).Earlier studies support an inverse correlation between circulating HDL-C and coronary risk in patients with normal or elevated LDL-C.This study involved 4,188 patients attending the Palo Alto Veterans Administration Medical Center or affiliated clinics with LDL-C levels below 60 mg/dl. Outcomes were examined 1 year after the index LDL-C date. The combined primary end point was myocardial injury or hospitalization from ischemic heart disease. The secondary end point was all-cause mortality.Mean HDL-C levels (mg/dl) by quartile (Q) were: Q1 28 mg/dl, Q2 36 mg/dl, Q3 43 mg/dl, and Q4 63 mg/dl. The rate of myocardial injury or hospitalization for ischemic heart disease showed an inverse relationship to HDL-C (adjusted odds ratios: Q1 1.59 [95% confidence interval (CI) 1.16 to 2.19], Q2 1.39 [95% CI 1.01 to 1.92], Q3 1.33 [95% CI 0.96 to 1.84], and Q4 reference) that persisted regardless of statin use or recent myocardial injury. Analyzing HDL-C as a continuous variable revealed a 10% [95% CI 3% to 17%] increase in the combined end point of myocardial injury or hospitalization for ischemic heart disease for every 10-mg/dl decrease in HDL-C. The unadjusted and adjusted incidence of all-cause mortality demonstrated a U-shaped relationship to HDL-C (adjusted odds ratios: Q1 1.13 [95% CI 0.79 to 1.62], Q2 0.97 [95% CI 0.67 to 1.40], Q3 0.74 [95% CI 0.50 to 1.09], and Q4 reference).The inverse relationship between HDL-C and coronary risk persists even among patients with LDL-C below 60 mg/dl, although a U-shaped relationship is observed between HDL-C and all-cause mortality.

    View details for DOI 10.1016/j.jacc.2007.07.086

    View details for Web of Science ID 000252510300008

    View details for PubMedID 18174036

  • Clinical dilemmas in treating left ventricular thrombus. International journal of cardiology Leeper, N. J., Gupta, A., Schnittger, I., Wu, J. C. 2007; 114 (3): e118-9

    View details for PubMedID 17049652

  • Clinical significance of HDL-c levels among patients with LDL-c less than 60 mg/dl deGoma, E., Leeper, N. J., Heidenreich, P. A. LIPPINCOTT WILLIAMS & WILKINS. 2006: 899
  • Statin use in patients with extremely low LDL levels is associated with improved survival Leeper, N. J., Ardehali, R., DeGoma, E. M., Heidenreich, P. A. LIPPINCOTT WILLIAMS & WILKINS. 2006: 827–28
  • Right coronary cameral fistula resulting from surgery of double chamber right ventricle. Journal of the American Society of Echocardiography Leeper, N. J., Gupta, A., Murphy, D. J., Wu, J. C. 2006; 19 (9): 1191 e9-11

    View details for PubMedID 16950481

  • The effect of preoperative statin therapy on cardiovascular outcomes in patients undergoing infrainguinal vascular surgery INTERNATIONAL JOURNAL OF CARDIOLOGY Ward, R. P., Leeper, N. J., Kirkpatrick, J. N., Lang, R. M., Sorrentino, M. J., Williams, K. A. 2005; 104 (3): 264-268

    Abstract

    Patients undergoing vascular surgery are at increased risk for perioperative cardiovascular (CV) complications. Our goal was to determine the effect of preoperative statin therapy on perioperative cardiac and vascular outcomes, and long-term survival in patients undergoing infrainguinal vascular bypass surgery.We retrospectively reviewed consecutive infrainguinal vascular bypass surgeries on 446 patients performed between 1995-2001 at the University of Chicago Medical Center. Information was collected on preoperative statin and beta-blocker use, baseline characteristics, perioperative cardiac and major vascular complications, and length of stay (LOS). Long-term survival was assessed using the Social Security Death Index (SSDI).Thirty day perioperative complications included all-cause mortality (2.5%), CV mortality (1.8%), myocardial infarction (MI) (4.7%), stroke (1.1%), and major peripheral vascular complications (12.8%), and the composite of cardiac and vascular complications [combined CV complications] (17.9%). Statin therapy was associated with fewer combined CV complications (6.9% vs 20.1%, p=0.008), and a shorter LOS (6.4 vs 9.7 days, p=0.007). On multivariate logistic regression analysis, adjusting for significant baseline characteristics including beta-blocker use, statin therapy was independently associated fewer combined CV complications (odds ratio (OR) 0.36, 95% confidence interval (CI) 0.14-0.93, p=0.035) and a shorter LOS (OR 1.49, 95% CI 1.14-1.95, p=0.003). In a mean follow up period of 5.5 years, 215 deaths (48%) occurred. Statin therapy was independently associated with improved long-term survival (OR 0.52, 95% CI 0.32-0.84, p<0.004), after adjusting for significant baseline characteristics.Preoperative statin therapy is associated with fewer combined perioperative cardiac and major vascular complications, a shorter length of stay, and improved long-term survival in patients undergoing infrainguinal vascular bypass surgery.

    View details for DOI 10.1016/j.ijcard.2004.10.030

    View details for Web of Science ID 000232752700004

    View details for PubMedID 16186054

  • One surprise after another NEW ENGLAND JOURNAL OF MEDICINE Leeper, N. J., Wener, L. S., Dhaliwal, G., Saint, S., Wachter, R. M. 2005; 352 (14): 1474-1479
  • Interleukin-6 causes endothelial barrier dysfunction via the protein kinase C pathway 35th Annual Meeting of the Association-for-Academic-Surgery Desai, T. R., Leeper, N. J., Hynes, K. L., Gewertz, B. L. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2002: 118–23

    Abstract

    Elevated levels of interleukin-6 (IL-6) have been identified in a variety of systemic inflammatory states that are associated with endothelial barrier dysfunction, but the specific effect of IL-6 on endothelial permeability and the mechanism of action have not been fully examined. The current study evaluated the effect of IL-6 on endothelial permeability and on the distribution of the tight junctional protein ZO-1 and cytoskeletal actin. We also assessed the role of protein kinase C (PKC) in this process.Confluent monolayers of human umbilical vein endothelial cells (n = 6) were exposed to IL-6 (50-500 ng/ml) in the presence or absence of the PKC inhibitor Gö6976 (0.1 microM). Transendothelial electrical resistance (TEER) was measured at the onset of exposure and at 6-h intervals and compared with that of control cells using ANOVA with a Bonferroni multiple comparison test. Additional monolayers were exposed to IL-6, stained for ZO-1 and F-actin, and evaluated via fluorescence microscopy.Interleukin-6 increased endothelial permeability as measured by TEER in a dose- and time-dependent manner. In the presence of PKC inhibitor, the IL-6-mediated increase in permeability was attenuated (18-h TEER 73% of control with IL-6 exposure vs 95% of control with IL-6 + Gö6976 inhibitor, P < 0.01). Microscopy revealed that permeability changes were accompanied by a redistribution of the tight junctional protein ZO-1 and cytoskeletal actin, increased cell contraction, and disorganization of the intercellular borders. Conclusions. The inflammatory cytokine IL-6 is an important mediator of increased endothelial permeability via alterations in the ultrastructural distribution of tight junctions and morphologic changes in cell shape. PKC is a critical intracellular messenger in these IL-6-mediated changes. A better understanding of this mechanism should allow the determination of rational treatment strategies for endothelial barrier dysfunction which occurs in inflammatory states.

    View details for DOI 10.1006/jsre.2002.6415

    View details for Web of Science ID 000176074300008

    View details for PubMedID 12020130

  • Gender does not influence outcomes after iliac angioplasty 26th Annual Meeting of the Peripheral-Vascular-Surgery-Society Orr, J. D., Leeper, N. J., Funaki, B., Leef, J., Gewertz, B. L., Desai, T. R. ELSEVIER SCIENCE INC. 2002: 55–60

    Abstract

    The current study was undertaken to evaluate the potential influence of gender on iliac angioplasty outcomes. All iliac angioplasty procedures performed at a tertiary care center from 1994 to 1999 were reviewed. One hundred four angioplasties with or without stenting were performed in 44 women (56 limbs) and 40 men (48 limbs). Age and atherosclerotic risk factors were similar in men and women. Iliac angioplasty was performed for limb salvage in 41% of patients (39% female vs. 44% male; p = 0.65). There were no differences in degree of stenosis, lesion length, or initial angioplasty site. Female iliac arteries were more likely to be occluded (21% vs. 6%; p = 0.03); mean iliac artery luminal diameter was smaller in women than in men (6.5 +/- 0.5 mm vs. 8.2 +/- 0.6 mm; p < 0.001). After a median follow-up of 13 months, there were no significant differences in 2-year primary patency, endovascular primary-assisted patency, or limb salvage rates between women and men. Despite having smaller iliac arteries and a higher incidence of arterial occlusion before treatment, women had outcomes similar to those of men after iliac angioplasty. The current results support the initial use of angioplasty to treat common and external iliac artery occlusive disease in both women and men.

    View details for DOI 10.1007/s10016-001-0131-7

    View details for Web of Science ID 000174307700010

    View details for PubMedID 11904805

  • Regulated expression of a unique lipase in endothelial cells suggests a local role in disease-associated lipid metabolism in the blood vessel wall Hirata, K., Dichek, H. L., Choi, S. Y., Leeper, N. J., Cooper, A. D., Quertermous, T. LIPPINCOTT WILLIAMS & WILKINS. 1999: 610–10
  • Tetracycline-regulatable expression vectors tightly regulate in vitro gene expression of secreted proteins GENE Sturtz, F. G., Cioffi, L., Wittmer, S., Sonk, M. J., Shafer, A., Li, Y. S., Leeper, N. J., Smith-Gbur, J., Shulok, J., Platika, D. 1998; 221 (2): 279-285

    Abstract

    The regulation of gene expression by the tetracycline system has attracted a high level of interest in the recent past. However, expression of secreted proteins has not been evaluated precisely. In this study, we constructed two versions of a one-plasmid system containing the elements necessary for the regulation of gene expression. The regulatable elements and the selectable marker (Neor) were set up in two different configurations, pTRIN31 and pTRIN76. With these two regulatable versions, the levels of protein expression after transfection into the NIH/3T3 cell line were measured by insertion of three different genes encoding the secreted proteins (hGH, ApoE3, hGM-CSF). The maximum levels of gene expression obtained with the pTRIN76-derived plasmids were 100ng/24h/106 cells for hGH, 427ng/24h/106 cells for ApoE3 and 108ng/24h/106 cells for hGM-CSF. For the pTRIN31-derived plasmids the maximum levels were 2.7ng/24h/106 cells for hGH and 47ng/24h/106 for ApoE3. Both plasmids give rise to an expression of the transfected gene that can be tightly regulated by three different molecules: tetracycline, minocycline and doxycycline. The levels of the secreted proteins are below the detectable level when the reporter genes are repressed. This repression is reversible within 48h after the regulator has been removed from the medium.

    View details for Web of Science ID 000077027300013

    View details for PubMedID 9795241