Advances in Proximity Ligation in situ Hybridization (PLISH)
BIO-PROTOCOL
Nagendran, M., Andruska, A. M., Harbury, P. B., Desai, T. J.
2020; 10 (21)
A Notch3-Marked Subpopulation of Vascular Smooth Muscle Cells is the Cell of Origin for Occlusive Pulmonary Vascular Lesions.
Circulation
Steffes, L. C., Froistad, A. A., Andruska, A., Boehm, M., McGlynn, M., Zhang, F., Zhang, W., Hou, D., Tian, X., Miquerol, L., Nadeau, K., Metzger, R. J., Spiekerkoetter, E., Kumar, M. E.
2020
Abstract
Background: Pulmonary arterial hypertension (PAH) is a fatal disease characterized by profound vascular remodeling in which pulmonary arteries narrow due to medial thickening and occlusion by neointimal lesions, resulting in elevated pulmonary vascular resistance and right heart failure. Therapies targeting the neointima would represent a significant advance in PAH treatment, however our understanding of the cellular events driving neointima formation, and the molecular pathways that control them, remains limited. Methods: We comprehensively map the stepwise remodeling of pulmonary arteries in a robust, chronic inflammatory mouse model of pulmonary hypertension. This model demonstrates pathologic features of the human disease, including increased right ventricular pressures, medial thickening, neointimal lesion formation, elastin breakdown, increased anastomosis within the bronchial circulation, and perivascular inflammation. Using genetic lineage tracing, clonal analysis, multiplexed in situ hybridization, immunostaining, deep confocal imaging and staged pharmacologic inhibition we define the cell behaviors underlying each stage of vascular remodeling and identify a pathway required for neointima formation. Results: Neointima arises from smooth muscle cells (SMCs) and not endothelium. Medial SMCs proliferate broadly to thicken the media, after which a small number of SMCs are selected to establish the neointima. These neointimal founder cells subsequently undergoing massive clonal expansion to form occlusive neointimal lesions. The normal pulmonary artery SMC population is heterogeneous and we identify a Notch3-marked minority subset of SMCs as the major neointimal cell of origin. Notch signaling is specifically required for the selection of neointimal founder cells, and Notch inhibition significantly improves pulmonary artery pressure in animals with pulmonary hypertension. Conclusions: This work describes the first nongenetically driven murine model of PH that generates robust and diffuse occlusive neointimal lesions across the pulmonary vascular bed and does so in a stereotyped timeframe. We uncover distinct cellular and molecular mechanisms underlying medial thickening and neointima formation and highlight novel transcriptional, behavioral and pathogenic heterogeneity within pulmonary artery SMCs. In this model, inflammation is sufficient to generate characteristic vascular pathologies and physiologic measures of human PAH. We hope that identifying the molecular cues regulating each stage of vascular remodeling will open new avenues for therapeutic advancements in the treatment of PAH.
View details for DOI 10.1161/CIRCULATIONAHA.120.045750
View details for PubMedID 32794408
Abstract
Since its association with familial pulmonary arterial hypertension (PAH) in 2000, Bone Morphogenetic Protein Receptor II (BMPR2) and its related signaling pathway have become recognized as a key regulator of pulmonary vascular homeostasis. Herein, we define BMPR2 deficiency as either an inactivation of the receptor, decreased receptor expression, or an impairment of the receptor's downstream signaling pathway. Although traditionally the phenotypic consequences of BMPR2 deficiency in PAH have been thought to be limited to the pulmonary vasculature, there is evidence that abnormalities in BMPR2 signaling may have consequences in many other organ systems and cellular compartments. Revisiting how BMPR2 functions throughout health and disease in cells and organs beyond the lung vasculature may provide insight into the contribution of these organ systems to PAH pathogenesis as well as the potential systemic manifestation of PAH. Here we review our knowledge of the consequences of BMPR2 deficiency across multiple organ systems.
View details for PubMedID 30149506
Abstract
RATIONALE: Pulmonary arterial hypertension (PAH) is characterized by progressive narrowing of pulmonary arteries resulting in right heart failure and death. Bone Morphogenetic Protein Receptor type-2 (BMPR2) mutations account for most familial PAH (FPAH) forms while reduced BMPR2 is present in many idiopathic PAH (IPAH) forms, suggesting dysfunctional BMPR2 signaling to be a key feature of PAH. Modulating BMPR2 signaling is therapeutically promising, yet how BMPR2 is downregulated in PAH is unclear.OBJECTIVES: We intended to identify and pharmaceutically target BMPR2 modifier genes to improve PAH.METHODS: We combined siRNA High Throughput Screening (HTS) of >20,000 genes with a multi-cohort analysis of publicly available PAH RNA expression data to identify clinically relevant BMPR2-modifiers. After confirming gene dysregulation in PAH patient tissue, we determined the functional roles of BMPR2-modifiers in vitro and tested the repurposed drug Enzastaurin for its propensity to improve experimental PH.MEASUREMENTS AND MAIN RESULTS: We discovered Fragile Histidine Triad (FHIT) as a novel BMPR2-modifier. BMPR2 and FHIT expression were reduced in PAH patients. FHIT reductions were associated with endothelial and smooth muscle cell dysfunction, rescued by Enzastaurin through a dual mechanism: upregulation of FHIT as well as miR17-5 repression. Fhit-/- mice had exaggerated hypoxic PH and failed to recover in normoxia. Enzastaurin reversed PH in the Sugen5416/Hypoxia/Normoxia rat model, by improving Right Ventricular Systolic Pressure (RVSP), RV hypertrophy, cardiac fibrosis and vascular remodeling.CONCLUSIONS: This study highlights the importance of the novel BMPR2 modifier FHIT in PH and the clinical value of the repurposed drug Enzastaurin as a potential novel therapeutic strategy to improve PAH.
View details for PubMedID 30107138
Abstract
Hospital readmissions for pneumonia occur often and are difficult to predict. For fiscal year 2013, the Centers for Medicare & Medicaid Services readmission penalties have been applied to acute myocardial infarction, heart failure, and pneumonia. However, the overall impact of pneumonia pathogen characterization on hospital readmission is undefined.This was a retrospective 6-year cohort study (August 2007 to September 2013).We evaluated 9,624 patients with a discharge diagnosis of pneumonia. Among these patients, 4,432 (46.1%) were classified as having culture-negative pneumonia, 1,940 (20.2%) as having pneumonia caused by antibiotic-susceptible bacteria, 2,991 (31.1%) as having pneumonia caused by potentially antibiotic-resistant bacteria, and 261 (2.7%) as having viral pneumonia. The 90-day hospital readmission rate for survivors (n = 7,637, 79.4%) was greatest for patients with pneumonia attributed to potentially antibiotic-resistant bacteria (11.4%) followed by viral pneumonia (8.3%), pneumonia attributed to antibiotic-susceptible bacteria (6.6%), and culture-negative pneumonia (5.8%) (P < .001). Multiple logistic regression analysis identified pneumonia attributed to potentially antibiotic-resistant bacteria to be independently associated with 90-day readmission (OR, 1.75; 95% CI, 1.56-1.97; P < .001). Other independent predictors of 90-day readmission were Charlson comorbidity score > 4, cirrhosis, and chronic kidney disease. Culture-negative pneumonia was independently associated with lower risk for 90-day readmission.Readmission after hospitalization for pneumonia is relatively common and is related to pneumonia pathogen characterization. Pneumonia attributed to potentially antibiotic-resistant bacteria is associated with an increased risk for 90-day readmission, whereas culture-negative pneumonia is associated with lower risk for 90-day readmission.
View details for DOI 10.1378/chest.14-2129
View details for Web of Science ID 000359003000031
View details for PubMedID 25429607
Abstract
Stroke is a significant complication in patients supported with continuous-flow left ventricular assist devices (CF-LVAD) and hypertension is a significant risk factor for stroke, but the association between blood pressure and stroke in LVAD patients is not well characterized.We identified 275 consecutive patients who survived implant hospitalization between January 2005 and April 2013. Patients were grouped according to systolic blood pressure (SBP) as above a median and below a median of 100 mm Hg by their averaged systolic blood pressure during the 48 hours before discharge from implantation hospitalization. The groups were compared for the primary outcome of time to stroke.The above-median SBP group had mean SBP of 110 mm Hg and the below-median SBP group had mean SBP of 95 mm Hg. There were no significant between-group differences in body mass index, smoking, vascular disease, hypertension, atrial fibrillation, or prior stroke. During a mean follow-up of 16 months, stroke occurred in 16% of the above-median SBP group vs in 7% of the below-median SBP group (hazard ratio, 2.38; 95% confidence interval, 1.11-5.11), with a similar proportion of hemorrhagic and ischemic strokes in each group. In Cox proportional hazard models adjusting for age, diabetes, or prior stroke, the hazard ratio remained statistically significant. SBP as a continuous variable predictor of stroke had an area under the curve of 0.64 in a receiver operating characteristic curve analysis.In this large, CF-LVAD cohort, elevated SBP was independently associated with a greater risk of subsequent stroke. These results identify management of hypertension as a potential modifiable risk factor for reducing the incidence of stroke in patients supported by CF-LVAD.
View details for DOI 10.1016/j.healun.2014.09.042
View details for PubMedID 25540881
View details for PubMedCentralID PMC4402112
Abstract
Neurons cultured on multielectrode arrays almost always lack external stimulation except during the acute experimental phase. We have investigated the effects of chronic stimulation during the course of development in cultured hippocampal neural networks by applying paired pulses at half of the electrodes for 0, 1 or 3 r/day for 8 days. Spike latencies increased from 4 to 16 ms as the distance from the stimulus increased from 200 to 1700 microm, suggesting an average of four synapses over this distance. Compared to no chronic stimulation, our results indicate that chronic stimulation increased evoked spike counts per stimulus by 50% at recording sites near the stimulating electrode and increased the instantaneous firing rate. On trials where both pulses elicited responses, spike count was 40-80% higher than when only one of the pulses elicited a response. In attempts to identify spike amplitude plasticity, we found mainly amplitude variation with different latencies suggesting recordings from neurons with different identities. These data suggest plastic network changes induced by chronic stimulation that enhance the reliability of information transmission and the efficiency of multisynaptic network communication.
View details for DOI 10.1088/1741-2560/7/1/016008
View details for PubMedID 20083862
View details for PubMedCentralID PMC3775841
