Carsten Riether, Christian Schürch, Adrian Ochsenbein, Karen Silence. "United States Patent 10,391,168 B1 Anti-CD70 combination therapy", University of Bern, Aug 27, 2019
The coronavirus SARS-CoV-2 is the causative agent of the ongoing severe acute respiratory disease pandemic COVID-19. Tissue and cellular tropism is one key to understanding the pathogenesis of SARS-CoV-2. We investigate the expression and subcellular localization of the SARS-CoV-2 receptor, angiotensin-converting enzyme 2 (ACE2), within the upper (nasal) and lower (pulmonary) respiratory tracts of human donors using a diverse panel of banked tissues. Here, we report our discovery that the ACE2 receptor protein robustly localizes within the motile cilia of airway epithelial cells, which likely represents the initial or early subcellular site of SARS-CoV-2 viral entry during host respiratory transmission. We further determine whether ciliary ACE2 expression in the upper airway is influenced by patient demographics, clinical characteristics, comorbidities, or medication use, and show the first mechanistic evidence that the use of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II receptor blockers (ARBs) does not increase susceptibility to SARS-CoV-2 infection through enhancing the expression of ciliary ACE2 receptor. These findings are crucial to our understanding of the transmission of SARS-CoV-2 for prevention and control of this virulent pathogen.
View details for DOI 10.1038/s41467-020-19145-6
View details for PubMedID 33116139
SARS-CoV-2 is causing a pandemic with currently>29 million confirmed cases and>900,000 deaths worldwide. The locations and mechanisms of virus entry into the human respiratory tract are incompletely characterized. We analyzed publicly available RNA microarray datasets for SARS-CoV-2 entry receptors and cofactors ACE2, TMPRSS2, BSG (CD147) and FURIN. We found that ACE2 and TMPRSS2 are upregulated in the airways of smokers. In asthmatics, ACE2 tended to be downregulated in nasal epithelium, and TMPRSS2 was upregulated in the bronchi. Furthermore, respiratory epithelia were negative for ACE-2 and TMPRSS2 protein expression while positive for BSG and furin, suggesting a possible alternative entry route for SARS-CoV-2.
View details for DOI 10.1186/s12931-020-01521-x
View details for PubMedID 32993656
Serum acetate increases upon systemic infection. Acutely, assimilation of acetate expands the capacity of memory CD8+ Tcells to produce IFN-gamma. Whether acetate modulates memory CD8+ Tcell metabolism and function during pathogen re-encounter remains unexplored. Here we show that at sites of infection, high acetate concentrations are being reached, yet memory CD8+ Tcells shut down the acetate assimilating enzymes ACSS1 and ACSS2. Acetate, being thus largely excluded from incorporation into cellular metabolic pathways, now had different effects, namely (1) directly activating glutaminase, thereby augmenting glutaminolysis, cellular respiration, and survival, and (2) suppressing TCR-triggered calcium flux, and consequently cell activation and effector cell function. Invivo, high acetate abundance at sites of infection improved pathogen clearance while reducing immunopathology. This indicates that, during different stages of the immune response, the same metabolite-acetate-induces distinct immunometabolic programs within the same cell type.
View details for DOI 10.1016/j.cmet.2020.07.004
View details for PubMedID 32738204
Redirecting the immune system in cancer treatment has led to remarkable responses in a subset of patients. Natural killer (NK) cells are innate lymphoid cells being explored as they engage tumor cells in different mechanisms compared to T cells, which could be exploited for treatment of nonresponders to current immunotherapies. NK cell therapies are monitored through measuring peripheral NK cell concentrations or changes in tumor volume over time. The former does not detect NK cells at the tumor site(s), and the latter is inaccurate for immunotherapies because of pseudoprogression. Therefore, new imaging methods are required as companion diagnostics for optimizing immunotherapies. Methods: Here we develop and complete pre-clinical in vivo validation of two antibody-based PET probes specific for NKp30, an activation natural cytotoxicity receptor expressed by human NK cells. Quantitative, multicolor flow cytometry during a variety of NK cell activation conditions was completed on primary human NK cells and the NK92MI cell line. Human renal cell carcinoma (RCC) tumors were stained for the NK cell receptors CD56, NKp30, and NKp46 to determine expression on tumor-infiltrating NK cells. An NKp30 antibody was radiolabeled with 64Cu or 89Zr and evaluated in subcutaneous xenografts and adoptive cell transfer mouse models. Results: Quantitative flow cytometry showed consistent expression of the NKp30 receptor during different activation conditions. NKp30 and NKp46 costained in RCC samples, demonstrating the expression of these receptors on tumor-infiltrating NK cells in human tumors, while tumor cells in one RCC sample expressed the peripheral NK marker CD56. Both PET tracers showed high stability and specificity in vitro and in vivo. Notably, 89Zr- NKp30Ab had higher on-target contrast compared to 64Cu-NKpAb at their respective terminal time points. 64Cu-NKp30Ab delineated NK cell trafficking to the liver and spleen in an adoptive cell transfer model. Conclusion: The consistent expression of NKp30 on NK cells makes it an attractive target for quantitative imaging. Immunofluorescence staining on human RCC samples demonstrated the advantages of NKp30 targeting versus the traditional CD56 for detection of tumor infiltrating NK cells. This work advances PET imaging of NK cells and supports the translation of imaging agents for immunotherapy monitoring.
View details for DOI 10.2967/jnumed.119.233163
View details for PubMedID 32532927
There is the notion that infection with a virulent intestinal pathogen induces generally stronger mucosal adaptive immunity than the exposure to an avirulent strain. Whether the associated mucosal inflammation is important or redundant for effective induction of immunity is, however, still unclear. Here we use a model of auxotrophic Salmonella infection in germ-free mice to show that live bacterial virulence factor-driven immunogenicity can be uncoupled from inflammatory pathogenicity. Although live auxotrophic Salmonella no longer causes inflammation, its mucosal virulence factors remain the main drivers of protective mucosal immunity; virulence factor-deficient, like killed, bacteria show reduced efficacy. Assessing the involvement of innate pathogen sensing mechanisms, we show MYD88/TRIF, Caspase-1/Caspase-11 inflammasome, and NOD1/NOD2 nodosome signaling to be individually redundant. In colonized animals we show that microbiota metabolite cross-feeding may recover intestinal luminal colonization but not pathogenicity. Consequent immunoglobulin A immunity and microbial niche competition synergistically protect against Salmonella wild-type infection.
View details for DOI 10.1038/s41467-020-15891-9
View details for PubMedID 32332737
Co-stimulatory signals, cytokines and transcription factors regulate the balance between effector and memory cell differentiation during T cell activation. Here, we analyse the role of the TRAF2-/NCK-interacting kinase (TNIK), a signaling molecule downstream of the tumor necrosis factor superfamily receptors such as CD27, in the regulation of CD8+ T cell fate during acute infection with lymphocytic choriomeningitis virus. Priming of CD8+ T cells induces a TNIK-dependent nuclear translocation of beta-catenin with consecutive Wnt pathway activation. TNIK-deficiency during T cell activation results in enhanced differentiation towards effector cells, glycolysis and apoptosis. TNIK signaling enriches for memory precursors by favouring symmetric over asymmetric cell division. This enlarges the pool of memory CD8+ T cells and increases their capacity to expand after re-infection in serial re-transplantation experiments. These findings reveal that TNIK is an important regulator of effector and memory T cell differentiation and induces a population of stem cell-like memory T cells.
View details for DOI 10.1038/s41467-020-15413-7
View details for PubMedID 32242021
BACKGROUND: Cryopreserved human peripheral blood mononuclear cells (PBMCs) are a commonly used sample type for a variety of immunological assays. Many factors can affect the quality of PBMCs, and careful consideration and validation of an appropriate PBMC isolation and cryopreservation method is important for well-designed clinical studies. A major point of divergence in PBMC isolation protocols is the collection of blood, either directly into vacutainers pre-filled with density gradient medium or the use of conical tubes containing a porous barrier to separate the density gradient medium from blood. To address potential differences in sample outcome, we isolated, cryopreserved, and compared PBMCs using parallel protocols differing only in the use of one of two common tube types for isolation.METHODS: Whole blood was processed in parallel using both Cell Preparation Tubes (CPT, BD Biosciences) and Lymphoprep Tubes (Axis-Shield) and assessed for yield and viability prior to cryopreservation. After thawing, samples were further examined by flow cytometry for cell yield, cell viability, frequency of 10 cell subsets, and capacity for stimulation-dependent CD4+ and CD8+ T cell intracellular cytokine production.RESULTS: No significant differences in cell recovery, viability, frequency of immune cell subsets, or T cell functionality between PBMC samples isolated using CPT or Lymphoprep tubes were identified.CONCLUSION: CPT and Lymphoprep tubes are effective and comparable methods for PBMC isolation for immunological studies.
View details for DOI 10.1186/s12865-020-00345-0
View details for PubMedID 32228458
Antitumoral immunity requires organized, spatially nuanced interactions between components of the immune tumor microenvironment (iTME). Understanding this coordinated behavior in effective versus ineffective tumor control will advance immunotherapies. We re-engineered co-detection by indexing (CODEX) for paraffin-embedded tissue microarrays, enabling simultaneous profiling of 140 tissue regions from 35 advanced-stage colorectal cancer (CRC) patients with 56 protein markers. We identified nine conserved, distinct cellular neighborhoods (CNs)-a collection of components characteristic of the CRC iTME. Enrichment of PD-1+CD4+ T cells only within a granulocyte CN positively correlated with survival in a high-risk patient subset. Coupling of tumor and immune CNs, fragmentation of T cell and macrophage CNs, and disruption of inter-CN communication was associated with inferior outcomes. This study provides a framework for interrogating how complex biological processes, such as antitumoral immunity, occur through concerted actions of cells and spatial domains.
View details for DOI 10.1016/j.cell.2020.07.005
View details for PubMedID 32763154
Multiple myeloma (MM) is a plasma cell malignancy and the second most common hematological neoplasm in adults, comprising 1.8% of all cancers. With an annual incidence of ~30,770 cases in the United States, MM has a high mortality rate, leading to 12,770 deaths per year. MM is a genetically complex, highly heterogeneous malignancy, with significant inter- and intra-patient clonal variability. Recent years have witnessed dramatic improvements in the diagnostics, classification, and treatment of MM. However, patients with high-risk disease have not yet benefited from therapeutic advances. High-risk patients are often primary refractory to treatment or relapse early, ultimately resulting in progression toward aggressive end-stage MM, with associated extramedullary disease or plasma cell leukemia. Therefore, novel treatment modalities are needed to improve the outcomes of these patients. Bispecific antibodies (BsAbs) are immunotherapeutics that simultaneously target and thereby redirect effector immune cells to tumor cells. BsAbs have shown high efficacy in B cell malignancies, including refractory/relapsed acute lymphoblastic leukemia. Various BsAbs targeting MM-specific antigens such as B cell maturation antigen (BCMA), CD38, and CD138 are currently in pre-clinical and clinical development, with promising results. In this review, we outline these advances, focusing on BsAb drugs, their targets, and their potential to improve survival, especially for high-risk MM patients. In combination with current treatment strategies, BsAbs may pave the way toward a cure for MM.
View details for DOI 10.3389/fimmu.2020.00501
View details for PubMedID 32391000
Influenza is a significant cause of morbidity and mortality worldwide. Here we show changes in the abundance and activation states of more than 50 immune cell subsets in 35 individuals over 11 time points during human A/California/2009 (H1N1) virus challenge monitored using mass cytometry along with other clinical assessments. Peak change in monocyte, B cell, and T cell subset frequencies coincided with peak virus shedding, followed by marked activation of T and NK cells. Results led to the identification of CD38 as a critical regulator of plasmacytoid dendritic cell function in response to influenza virus. Machine learning using study-derived clinical parameters and single-cell data effectively classified and predicted susceptibility to infection. The coordinated immune cell dynamics defined in this study provide a framework for identifying novel correlates of protection in the evaluation of future influenza therapeutics.
View details for DOI 10.1172/JCI137265
View details for PubMedID 33044226
Recent research has dramatically advanced our understanding of the genetic basis of multiple myeloma (MM). MM displays enormous inter- and intratumoral heterogeneity, and underlies a clonal evolutionary process driven and shaped by diverse factors such as clonal competition, tumor microenvironment, host immunity, and therapy. Two main cytogenetic groups are distinguished: MM with recurrent translocations involving the immunoglobulin heavy chain locus and MM with hyperdiploidy involving the odd chromosomes. The disease virtually always starts with a preneoplastic prodromal phase-monoclonal gammopathy of undetermined significance-that variably progresses to symptomatic MM within a few months or many years. Tumor heterogeneity and its evolution in space and time have important consequences for the clinical management and outcome of MM patients. At diagnosis, spatial intratumoral heterogeneity poses a challenge for classification and risk stratification. During maintenance therapy, clonal evolution may complicate disease monitoring and promote drug resistance. Upon progression or transformation, identifying the dominant disease-driving neoplastic clones and elucidating their properties are key to tailor personalized therapy. In this review, we discuss tumor heterogeneity and clonal evolution in MM, integrating pathological, radiological, molecular genetics, and clinical data. Current and prospective classification schemes and prognostic parameters, incorporating new genetic and proteomic discoveries and advances in imaging, are highlighted. In addition, the roles of the tumor microenvironment, host immunity, and resistance mutations, and their effects on therapy, are discussed. An improved understanding of high-risk disease, tumor heterogeneity, and clonal evolution will guide future therapies and may ultimately lead towards a cure for MM.
View details for DOI 10.1007/s00428-019-02725-3
View details for PubMedID 31848687
View details for Web of Science ID 000496473200424
View details for Web of Science ID 000509478706203
Transformative technologies are enabling the construction of three-dimensional maps of tissues with unprecedented spatial and molecular resolution. Over the next seven years, the NIH Common Fund Human Biomolecular Atlas Program (HuBMAP) intends to develop a widely accessible framework for comprehensively mapping the human body at single-cell resolution by supporting technology development, data acquisition, and detailed spatial mapping. HuBMAP will integrate its efforts with other funding agencies, programs, consortia, and the biomedical research community at large towards the shared vision of a comprehensive, accessible three-dimensional molecular and cellular atlas of the human body, in health and under various disease conditions.
View details for DOI 10.1038/s41586-019-1629-x
View details for Web of Science ID 000489784200035
View details for PubMedID 31597973
View details for PubMedCentralID PMC6800388
Lobular neoplasia (LN), invasive lobular breast cancer (ILBC) and related pleomorphic variants represent a distinct group of neoplastic mammary gland lesions. This study assessed the inter-observer agreement of histological grading in a series of ILBC and LN. 54 cases (36x ILBC, 18x LN) were evaluated by 17 observers. 3978 classification calls on various histological features, including nuclear grade, proliferative activity (Ki67 immunohistochemistry, categorical scoring), histological grade and pleomorphism were obtained. Pairwise Cohen's kappa values were calculated and compared between various features and different observer subsets with variable histomorphological experience. In ILBC, pairwise inter-observer agreement for histological grade ranged from poor to almost perfect concordance and was higher in advanced and experienced histopathologists compared with beginners (P<0.001). Agreement for proliferation (Ki67) ranged from slight to almost perfect concordance and was also higher in advanced and experienced histopathologists (P<0.001). Considering different features, agreement for proliferation (Ki67) was superior to agreement for histological grade and nuclear grade, even among advanced and experienced histopathologists (P<0.001). In LN, agreement for B-classification ranged from poor to almost perfect concordance and was higher in advanced and experienced histopathologists (P<0.001). Considering different features, agreement for proliferation (Ki67 in LN) was superior to subclassification agreement based on conventional features, such as acinar distention and nuclear grade (P<0.001). In summary, pairwise inter-observer concordance of histological grading of ILBC and LN is dependent on histomorphological experience. Assessment of proliferation by Ki67 immunohistochemistry is associated with favorable inter-observer agreement and can improve histological grading of ILBC as well as LN.
View details for DOI 10.1016/j.prp.2019.152611
View details for PubMedID 31551174
Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human cancers with a median survival of only 3-6 months. Standard treatment options and even targeted therapies have so far failed to improve long-term overall survival. Thus, novel treatment modalities for ATC, such as immunotherapy, are urgently needed. CD47 is a "don't eat me" signal which prevents cancer cells from phagocytosis by binding to signal regulatory protein ? (SIRP?) on macrophages. So far, the role of macrophages and the CD47-SIRP? signaling axis in ATC is not well understood.We analyzed 19 primary human ATCs for macrophage markers, CD47 expression and immune checkpoints by immunohistochemistry. ATC cell lines and a fresh ATC sample were assessed by flow cytometry for CD47 expression and macrophage infiltration, respectively. CD47 was blocked in phagocytosis assays of co-cultured macrophages and ATC cell lines. Anti-CD47 antibody treatment was administered to ATC cell line xenotransplanted immunocompromised mice as well as to tamoxifen-induced ATC double-transgenic mice.Human ATC samples were heavily infiltrated by CD68- and CD163-expressing tumor-associated macrophages (TAMs), and expressed CD47 and calreticulin, the dominant pro-phagocytic molecule. In addition, ATC tissues expressed the immune checkpoint molecules programmed cell death 1 (PD-1) and PD-1 ligand 1 (PD-L1). Blocking CD47 promoted the phagocytosis of ATC cell lines by macrophages in vitro. Anti-CD47 antibody treatment of ATC xenotransplanted mice increased the frequency of TAMs, enhanced the expression of macrophage activation markers, augmented tumor cell phagocytosis, and suppressed tumor growth. In double-transgenic ATC mice, CD47 was expressed on tumor cells and blocking CD47 increased TAM frequencies.Targeting CD47 or CD47 in combination with PD-1 may potentially improve the outcomes of ATC patients and may represent a valuable addition to the current standard of care.
View details for PubMedID 30938231
Drug resistance and relapse remain key challenges in pancreatic cancer. Here, we have used RNA sequencing (RNA-seq), chromatin immunoprecipitation (ChIP)-seq, and genome-wide CRISPR analysis to map the molecular dependencies of pancreatic cancer stem cells, highly therapy-resistant cells that preferentially drive tumorigenesis and progression. This integrated genomic approach revealed an unexpected utilization of immuno-regulatory signals by pancreatic cancer epithelial cells. In particular, the nuclear hormone receptor retinoic-acid-receptor-related orphan receptor gamma (ROR?), known to drive inflammation and T cell differentiation, was upregulated during pancreatic cancer progression, and its genetic or pharmacologic inhibition led to a striking defect in pancreatic cancer growth and a marked improvement in survival. Further, a large-scale retrospective analysis in patients revealed that ROR? expression may predict pancreatic cancer aggressiveness, as it positively correlated with advanced disease and metastasis. Collectively, these data identify an orthogonal co-option of immuno-regulatory signals by pancreatic cancer stem cells, suggesting that autoimmune drugs should be evaluated as novel treatment strategies for pancreatic cancer patients.
View details for PubMedID 30955884
Therapeutic monoclonal antibodies (mAbs) such as antibody-drug conjugates, ligand-receptor antagonists, immune checkpoint inhibitors and bispecific T cell engagers have shown impressive efficacy in the treatment of multiple human cancers. Numerous therapeutic mAbs that have been developed for myeloid neoplasms, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), are currently investigated in clinical trials. Because AML and MDS originate from malignantly transformed hematopoietic stem/progenitor cells-the so-called leukemic stem cells (LSCs) that are highly resistant to most standard drugs-these malignancies frequently relapse and have a high disease-specific mortality. Therefore, combining standard chemotherapy with antileukemic mAbs that specifically target malignant blasts and particularly LSCs or utilizing mAbs that reinforce antileukemic host immunity holds great promise for improving patient outcomes. This review provides an overview of therapeutic mAbs for AML and MDS. Antibody targets, the molecular mechanisms of action, the efficacy in preclinical leukemia models, and the results of clinical trials are discussed. New developments and future studies of therapeutic mAbs in myeloid neoplasms will advance our understanding of the immunobiology of these diseases and enhance current therapeutic strategies.
View details for DOI 10.3389/fonc.2018.00152
View details for Web of Science ID 000432577400001
View details for PubMedID 29868474
View details for PubMedCentralID PMC5968093
View details for Web of Science ID 000429308603413
View details for Web of Science ID 000459341002413
Acute myelogenous leukemia (AML) is initiated and maintained by leukemia stem cells (LSC). LSCs are therapy-resistant, cause relapse, and represent a major obstacle for the cure of AML. Resistance to therapy is often mediated by aberrant tyrosine kinase (TK) activation. These TKs primarily activate downstream signaling via STAT3/STAT5. In this study, we analyzed the potential to therapeutically target aberrant TK signaling and to eliminate LSCs via the multi-TK inhibitor Debio 0617B. Debio 0617B has a unique profile targeting key kinases upstream of STAT3/STAT5 signaling such as JAK, SRC, ABL, and class III/V receptor TKs. We demonstrate that expression of phospho-STAT3 (pSTAT3) in AML blasts is an independent prognostic factor for overall survival. Furthermore, phospho-STAT5 (pSTAT5) signaling is increased in primary CD34(+) AML stem/progenitors. STAT3/STAT5 activation depends on tyrosine phosphorylation, mediated by several upstream TKs. Inhibition of single upstream TKs did not eliminate LSCs. In contrast, the multi-TK inhibitor Debio 0617B reduced maintenance and self-renewal of primary human AML CD34(+) stem/progenitor cells in vitro and in xenotransplantation experiments resulting in long-term elimination of human LSCs and leukemia. Therefore, inhibition of multiple TKs upstream of STAT3/5 may result in sustained therapeutic efficacy of targeted therapy in AML and prevent relapses. Mol Cancer Ther; 16(8); 1497-510. ©2017 AACR.
View details for DOI 10.1158/1535-7163.MCT-16-0889
View details for PubMedID 28468777
Aberrant proliferation, symmetric self-renewal, increased survival, and defective differentiation of malignant blasts are key oncogenic drivers in acute myeloid leukemia (AML). Stem cell gene signatures predict poor prognosis in AML patients; however, with few exceptions, these deregulated molecular pathways cannot be targeted therapeutically. In this study, we demonstrate that the TNF superfamily ligand-receptor pair CD70/CD27 is expressed on AML blasts and AML stem/progenitor cells. CD70/CD27 signaling in AML cells activates stem cell gene expression programs, including the Wnt pathway, and promotes symmetric cell divisions and proliferation. Soluble CD27, reflecting the extent of CD70/CD27 interactions in vivo, was significantly elevated in the sera of newly diagnosed AML patients and is a strong independent negative prognostic biomarker for overall survival. Blocking the CD70/CD27 interaction by mAb induced asymmetric cell divisions and differentiation in AML blasts and AML stem/progenitor cells, inhibited cell growth and colony formation, and significantly prolonged survival in murine AML xenografts. Importantly, hematopoietic stem/progenitor cells from healthy BM donors express neither CD70 nor CD27 and were unaffected by blocking mAb treatment. Therefore, targeting CD70/CD27 signaling represents a promising therapeutic strategy for AML.
View details for DOI 10.1084/jem.20152008
View details for Web of Science ID 000394251400008
View details for PubMedID 28031480
View details for PubMedCentralID PMC5294846
The facts that cancer represents tissues consisting of heterogeneous neoplastic, as well as reactive, cell populations and that cancers of the same histotype may show profound differences in clinical behavior have long been recognized. With the advent of new technologies and the demands of precision medicine, the investigation of tumor heterogeneity has gained much interest. An understanding of intertumoral heterogeneity in patients with the same disease entity is necessary to optimally guide personalized treatment. In addition, increasing evidence indicates that different tumor areas or primary tumors and metastases in an individual patient can show significant intratumoral heterogeneity on different levels. This phenomenon can be driven by genomic instability, epigenetic events, the tumor microenvironment, and stochastic variations in cellular function and antitumoral therapies. These mechanisms may lead to branched subclonal evolution from a common progenitor clone, resulting in spatial variation between different tumor sites, disease progression, and treatment resistance. This review addresses tumor heterogeneity in lymphomas from a pathologist's viewpoint. The relationship between morphologic, immunophenotypic, and genetic heterogeneity is exemplified in different lymphoma entities and reviewed in the context of high-grade transformation and transdifferentiation. In addition, factors driving heterogeneity, as well as clinical and therapeutic implications of lymphoma heterogeneity, will be discussed.
View details for DOI 10.1159/000475530
View details for PubMedID 28719907
Citrobacter rodentium infection is a mouse model for the important human diarrheal infection caused by enteropathogenic E. coli (EPEC). The pathogenesis of both species is very similar and depends on their unique ability to form intimately epithelium-adherent microcolonies, also known as "attachment/effacement" (A/E) lesions. These microcolonies must be dynamic and able to self-renew by continuous re-infection of the rapidly regenerating epithelium. It is unknown whether sustained epithelial A/E lesion pathogenesis is achieved through re-infection by planktonic bacteria from the luminal compartment or local spread of sessile bacteria without a planktonic phase. Focusing on the earliest events as C. rodentium becomes established, we show here that all colonic epithelial A/E microcolonies are clonal bacterial populations, and thus depend on local clonal growth to persist. In wild-type mice, microcolonies are established exclusively within the first 18 hours of infection. These early events shape the ongoing intestinal geography and severity of infection despite the continuous presence of phenotypically virulent luminal bacteria. Mechanistically, induced resistance to A/E lesion de-novo formation is mediated by TLR-MyD88/Trif-dependent signaling and is induced specifically by virulent C. rodentium in a virulence gene-dependent manner. Our data demonstrate that the establishment phase of C. rodentium pathogenesis in vivo is restricted to a very short window of opportunity that determines both disease geography and severity.
View details for DOI 10.1371/journal.ppat.1006476
View details for PubMedID 28662171
View details for PubMedCentralID PMC5507559
View details for Web of Science ID 000370302502489
View details for Web of Science ID 000369270702222
Bile acids, important mediators of lipid absorption, also act as hormone-like regulators and as antimicrobial molecules. In all these functions their potency is modulated by a variety of chemical modifications catalyzed by bacteria of the healthy gut microbiota, generating a complex variety of secondary bile acids. Intestinal commensal organisms are well-adapted to normal concentrations of bile acids in the gut. In contrast, physiological concentrations of the various intestinal bile acid species play an important role in the resistance to intestinal colonization by pathogens such as Clostridium difficile. Antibiotic therapy can perturb the gut microbiota and thereby impair the production of protective secondary bile acids. The most important bile acid transformation is 7?-dehydroxylation, producing deoxycholic acid (DCA) and lithocholic acid (LCA). The enzymatic pathway carrying out 7?-dehydroxylation is restricted to a narrow phylogenetic group of commensal bacteria, the best-characterized of which is Clostridium scindens. Like many other intestinal commensal species, 7-dehydroxylating bacteria are understudied in vivo. Conventional animals contain variable and uncharacterized indigenous 7?-dehydroxylating organisms that cannot be selectively removed, making controlled colonization with a specific strain in the context of an undisturbed microbiota unfeasible. In the present study, we used a recently established, standardized gnotobiotic mouse model that is stably associated with a simplified murine 12-species "oligo-mouse microbiota" (Oligo-MM(12)). It is representative of the major murine intestinal bacterial phyla, but is deficient for 7?-dehydroxylation. We find that the Oligo-MM(12) consortium carries out bile acid deconjugation, a prerequisite for 7?-dehydroxylation, and confers no resistance to C. difficile infection (CDI). Amendment of Oligo-MM(12) with C. scindens normalized the large intestinal bile acid composition by reconstituting 7?-dehydroxylation. These changes had only minor effects on the composition of the native Oligo-MM(12), but significantly decreased early large intestinal C. difficile colonization and pathogenesis. The delayed pathogenesis of C. difficile in C. scindens-colonized mice was associated with breakdown of cecal microbial bile acid transformation.
View details for DOI 10.3389/fcimb.2016.00191
View details for PubMedID 28066726
View details for PubMedCentralID PMC5168579
In chronic myelogenous leukemia (CML), oncogenic BCR-ABL1 activates the Wnt pathway, which is fundamental for leukemia stem cell (LSC) maintenance. Tyrosine kinase inhibitor (TKI) treatment reduces Wnt signaling in LSCs and often results in molecular remission of CML; however, LSCs persist long term despite BCR-ABL1 inhibition, ultimately causing disease relapse. We demonstrate that TKIs induce the expression of the tumor necrosis factor (TNF) family ligand CD70 in LSCs by down-regulating microRNA-29, resulting in reduced CD70 promoter DNA methylation and up-regulation of the transcription factor specificity protein 1. The resulting increase in CD70 triggered CD27 signaling and compensatory Wnt pathway activation. Combining TKIs with CD70 blockade effectively eliminated human CD34(+) CML stem/progenitor cells in xenografts and LSCs in a murine CML model. Therefore, targeting TKI-induced expression of CD70 and compensatory Wnt signaling resulting from the CD70/CD27 interaction is a promising approach to overcoming treatment resistance in CML LSCs.
View details for DOI 10.1126/scitranslmed.aab1740
View details for Web of Science ID 000358739300005
View details for PubMedID 26223302
Myeloproliferative neoplasms (MPNs) are characterized by the clonal expansion of one or more myeloid cell lineage. In most cases, proliferation of the malignant clone is ascribed to defined genetic alterations. MPNs are also associated with aberrant expression and activity of multiple cytokines; however, the mechanisms by which these cytokines contribute to disease pathogenesis are poorly understood. Here, we reveal a non-redundant role for steady-state IL-33 in supporting dysregulated myelopoiesis in a murine model of MPN. Genetic ablation of the IL-33 signaling pathway was sufficient and necessary to restore normal hematopoiesis and abrogate MPN-like disease in animals lacking the inositol phosphatase SHIP. Stromal cell-derived IL-33 stimulated the secretion of cytokines and growth factors by myeloid and non-hematopoietic cells of the BM, resulting in myeloproliferation in SHIP-deficient animals. Additionally, in the transgenic JAK2V617F model, the onset of MPN was delayed in animals lacking IL-33 in radio-resistant cells. In human BM, we detected increased numbers of IL-33-expressing cells, specifically in biopsies from MPN patients. Exogenous IL-33 promoted cytokine production and colony formation by primary CD34+ MPN stem/progenitor cells from patients. Moreover, IL-33 improved the survival of JAK2V617F-positive cell lines. Together, these data indicate a central role for IL-33 signaling in the pathogenesis of MPNs.
View details for DOI 10.1172/JCI77347
View details for Web of Science ID 000357553300009
View details for PubMedID 26011644
View details for PubMedCentralID PMC4563674
Binding of CD47 to signal regulatory protein alpha (SIRP?), an inhibitory receptor, negatively regulates phagocytosis. In acute myeloid leukemia (AML), CD47 is overexpressed on peripheral blasts and leukemia stem cells and inversely correlates with survival. Aim of the study was to investigate the correlation between CD47 protein expression by immunohistochemistry (IHC) in a bone marrow (BM) tissue microarray (TMA) and clinical outcome in AML patients. CD47 staining on BM leukemia blasts was scored semi-quantitatively and correlated with clinical parameters and known prognostic factors in AML. Low (scores 0-2) and high (score 3) CD47 protein expression were observed in 75% and 25% of AML patients. CD47 expression significantly correlated with percentage BM blast infiltration and peripheral blood blasts. Moreover, high CD47 expression was associated with nucleophosmin (NPM1) gene mutations. In contrast, CD47 expression did not significantly correlate with overall or progression free survival or response to therapy. In summary, a BM TMA permits rapid and reproducible semi-quantitative analysis of CD47 protein expression by IHC. While CD47 expression on circulating AML blasts has been shown to be a negative prognostic marker for a very defined population of AML patients with NK AML, CD47 expression on AML BM blasts is not.
View details for DOI 10.1016/j.leukres.2015.04.007
View details for Web of Science ID 000355636700011
View details for PubMedID 25943033
View details for Web of Science ID 000349242702148
Neutropenia is probably the strongest known predisposition to infection with otherwise harmless environmental or microbiota-derived species. Because initial swarming of neutrophils at the site of infection occurs within minutes, rather than the hours required to induce "emergency granulopoiesis," the relevance of having high numbers of these cells available at any one time is obvious. We observed that germ-free (GF) animals show delayed clearance of an apathogenic bacterium after systemic challenge. In this article, we show that the size of the bone marrow myeloid cell pool correlates strongly with the complexity of the intestinal microbiota. The effect of colonization can be recapitulated by transferring sterile heat-treated serum from colonized mice into GF wild-type mice. TLR signaling was essential for microbiota-driven myelopoiesis, as microbiota colonization or transferring serum from colonized animals had no effect in GF MyD88(-/-)TICAM1(-/-) mice. Amplification of myelopoiesis occurred in the absence of microbiota-specific IgG production. Thus, very low concentrations of microbial Ags and TLR ligands, well below the threshold required for induction of adaptive immunity, sets the bone marrow myeloid cell pool size. Coevolution of mammals with their microbiota has probably led to a reliance on microbiota-derived signals to provide tonic stimulation to the systemic innate immune system and to maintain vigilance to infection. This suggests that microbiota changes observed in dysbiosis, obesity, or antibiotic therapy may affect the cross talk between hematopoiesis and the microbiota, potentially exacerbating inflammatory or infectious states in the host.
View details for DOI 10.4049/jimmunol.1400762
View details for Web of Science ID 000345023400055
View details for PubMedID 25305320
Cytotoxic CD8(+) T cells (CTLs) play a major role in host defense against intracellular pathogens, but a complete clearance of pathogens and return to homeostasis requires the regulated interplay of the innate and acquired immune systems. Here, we show that interferon ? (IFN?) secreted by effector CTLs stimulates hematopoiesis at the level of early multipotent hematopoietic progenitor cells and induces myeloid differentiation. IFN? did not primarily affect hematopoietic stem or progenitor cells directly. Instead, it promoted the release of hematopoietic cytokines, including interleukin 6 from bone marrow mesenchymal stromal cells (MSCs) in the hematopoietic stem cell niche, which in turn reduced the expression of the transcription factors Runx-1 and Cebp? in early hematopoietic progenitor cells and increased myeloid differentiation. Therefore, our study indicates that, during an acute viral infection, CTLs indirectly modulate early multipotent hematopoietic progenitors via MSCs in order to trigger the temporary activation of emergency myelopoiesis and promote clearance of the infection.
View details for DOI 10.1016/j.stem.2014.01.002
View details for Web of Science ID 000334766400010
View details for PubMedID 24561082
Triggering receptor expressed on myeloid cells-1 (TREM-1) is a potent amplifier of pro-inflammatory innate immune reactions. While TREM-1-amplified responses likely aid an improved detection and elimination of pathogens, excessive production of cytokines and oxygen radicals can also severely harm the host. Studies addressing the pathogenic role of TREM-1 during endotoxin-induced shock or microbial sepsis have so far mostly relied on the administration of TREM-1 fusion proteins or peptides representing part of the extracellular domain of TREM-1. However, binding of these agents to the yet unidentified TREM-1 ligand could also impact signaling through alternative receptors. More importantly, controversial results have been obtained regarding the requirement of TREM-1 for microbial control. To unambiguously investigate the role of TREM-1 in homeostasis and disease, we have generated mice deficient in Trem1. Trem1(-/-) mice are viable, fertile and show no altered hematopoietic compartment. In CD4(+) T cell- and dextran sodium sulfate-induced models of colitis, Trem1(-/-) mice displayed significantly attenuated disease that was associated with reduced inflammatory infiltrates and diminished expression of pro-inflammatory cytokines. Trem1(-/-) mice also exhibited reduced neutrophilic infiltration and decreased lesion size upon infection with Leishmania major. Furthermore, reduced morbidity was observed for influenza virus-infected Trem1(-/-) mice. Importantly, while immune-associated pathologies were significantly reduced, Trem1(-/-) mice were equally capable of controlling infections with L. major, influenza virus, but also Legionella pneumophila as Trem1(+/+) controls. Our results not only demonstrate an unanticipated pathogenic impact of TREM-1 during a viral and parasitic infection, but also indicate that therapeutic blocking of TREM-1 in distinct inflammatory disorders holds considerable promise by blunting excessive inflammation while preserving the capacity for microbial control.
View details for DOI 10.1371/journal.ppat.1003900
View details for Web of Science ID 000332640900051
View details for PubMedID 24453980
View details for PubMedCentralID PMC3894224
Chronic myeloid leukemia (CML) is a clonal myeloproliferative neoplasia arising from the oncogenic break point cluster region/Abelson murine leukemia viral oncogene homolog 1 translocation in hematopoietic stem cells (HSCs), resulting in a leukemia stem cell (LSC). Curing CML depends on the eradication of LSCs. Unfortunately, LSCs are resistant to current treatment strategies. The host's immune system is thought to contribute to disease control, and several immunotherapy strategies are under investigation. However, the interaction of the immune system with LSCs is poorly defined. In the present study, we use a murine CML model to show that LSCs express major histocompatibility complex (MHC) and co-stimulatory molecules and are recognized and killed by leukemia-specific CD8(+) effector CTLs in vitro. In contrast, therapeutic infusions of effector CTLs into CML mice in vivo failed to eradicate LSCs but, paradoxically, increased LSC numbers. LSC proliferation and differentiation was induced by CTL-secreted IFN-?. Effector CTLs were only able to eliminate LSCs in a situation with minimal leukemia load where CTL-secreted IFN-? levels were low. In addition, IFN-? increased proliferation and colony formation of CD34(+) stem/progenitor cells from CML patients in vitro. Our study reveals a novel mechanism by which the immune system contributes to leukemia progression and may be important to improve T cell-based immunotherapy against leukemia.
View details for DOI 10.1084/jem.20121229
View details for Web of Science ID 000315997000013
View details for PubMedID 23401488
View details for PubMedCentralID PMC3600910
The immune system is able to specifically target antigen-expressing cancer cells. The promise of immunotherapy was to eliminate cancer cells without harming normal tissue and, therefore, with no or very few side effects. Immunotherapy approaches have, for several decades, been tested against several tumours, most often against malignant melanoma. However, although detectable immune responses have regularly been induced, the clinical outcome has often been disappointing. The development of molecular methods and an improved understanding of tumour immunosurveillance led to novel immunotherapy approaches in the last few years. First randomised phase III trials proved that immunotherapy can prolong survival of patients with metastatic melanoma or prostate cancer. The development in the field is very rapid and various molecules (mainly monoclonal antibodies) that activate the immune system are currently being tested in clinical trials and will possibly change our treatment of cancer. The ultimate goal of any cancer therapy and also immunotherapy is to cure cancer. However, this depends on the elimination of the disease originating cancer stem cells. Unfortunately, cancer stem cells seem resistant to most available treatment options. Recent developments in immunotherapy may allow targeting these cancer stem cells specifically in the future. In this review, we summarise the current state of immunotherapy in clinical routine and the expected developments in the near future.
View details for DOI 10.4414/smw.2013.13734
View details for Web of Science ID 000321907200001
View details for PubMedID 23348718
Acute and chronic myeloid leukemia (AML, CML) are hematologic malignancies arising from oncogene-transformed hematopoietic stem/progenitor cells known as leukemia stem cells (LSCs). LSCs are selectively resistant to various forms of therapy including irradiation or cytotoxic drugs. The introduction of tyrosine kinase inhibitors has dramatically improved disease outcome in patients with CML. For AML, however, prognosis is still quite dismal. Standard treatments have been established more than 20?years ago with only limited advances ever since. Durable remission is achieved in less than 30% of patients. Minimal residual disease (MRD), reflected by the persistence of LSCs below the detection limit by conventional methods, causes a high rate of disease relapses. Therefore, the ultimate goal in the treatment of myeloid leukemia must be the eradication of LSCs. Active immunotherapy, aiming at the generation of leukemia-specific cytotoxic T cells (CTLs), may represent a powerful approach to target LSCs in the MRD situation. To fully activate CTLs, leukemia antigens have to be successfully captured, processed, and presented by mature dendritic cells (DCs). Myeloid progenitors are a prominent source of DCs under homeostatic conditions, and it is now well established that LSCs and leukemic blasts can give rise to "malignant" DCs. These leukemia-derived DCs can express leukemia antigens and may either induce anti-leukemic T cell responses or favor tolerance to the leukemia, depending on co-stimulatory or -inhibitory molecules and cytokines. This review will concentrate on the role of DCs in myeloid leukemia immunotherapy with a special focus on their generation, application, and function and how they could be improved in order to generate highly effective and specific anti-leukemic CTL responses. In addition, we discuss how DC-based immunotherapy may be successfully integrated into current treatment strategies to promote remission and potentially cure myeloid leukemias.
View details for DOI 10.3389/fimmu.2013.00496
View details for Web of Science ID 000209374100482
View details for PubMedID 24427158
View details for PubMedCentralID PMC3876024
Based on a single-case observation, the descriptive label "leiomyomatoid angiomatous neuroendocrine tumor" (LANT) has been tentatively applied to what was perceived as a possible novel type of dual-lineage pituitary neoplasm with biphasic architecture. We report on two additional examples of an analogous phenomenon encountered in male patients, aged 59 years (Case 1) and 91 years (Case 2). Both tumors were intra- and suprasellar masses, measuring 5.6 cm × 4.4 cm × 3.4 cm, and 2.7 cm × 2 cm × 1.7 cm, respectively. Histologically, Case 1 was an FSH-cell adenoma interwoven by vascularized connective tissue septa that tended to exhibit incremental stages of adventitial overgrowth. The epithelial component of Case 2 corresponded to an LH-cell adenoma, and lay partitioned by a maze of paucicellular to hyalinized vascular axes. Irrespective of architectural variations, perivascular spindle cells exhibited immunopositivity for vimentin, muscular actin, and smooth muscle actin. Conversely, negative results were obtained for CD34, EMA, S100 protein, GFAP, and TTF-1. Ultrastructural study failed to reveal metaplastic cell forms involving transitional features between adenohypophyseal-epithelial and mesenchymal-contractile phenotype. We propose that LANT be regarded as a peculiar reflection of maladaptive angiogenesis in some pituitary adenomas, rather than a genuine hybrid neoplasm. While no mechanistic clue is forthcoming to account for this distinctive pattern, hemodynamic strain through direct arterial - rather than portal - supply of the adenoma's capillary bed may be one such explanatory factor. The apparent predilection of the LANT pattern for macroadenomas of the gonadotroph cell lineage remains unexplained.
View details for DOI 10.1016/j.prp.2013.01.003
View details for Web of Science ID 000317093000004
View details for PubMedID 23419690
Signaling of the TNF receptor superfamily member CD27 activates costimulatory pathways to elicit T- and B-cell responses. CD27 signaling is regulated by the expression of its ligand CD70 on subsets of dendritic cells and lymphocytes. Here, we analyzed the role of the CD27-CD70 interaction in the immunologic control of solid tumors in Cd27-deficient mice. In tumor-bearing wild-type mice, the CD27-CD70 interaction increased the frequency of regulatory T cells (Tregs), reduced tumor-specific T-cell responses, increased angiogenesis, and promoted tumor growth. CD27 signaling reduced apoptosis of Tregs in vivo and induced CD4(+) effector T cells (Teffs) to produce interleukin-2, a key survival factor for Tregs. Consequently, the frequency of Tregs and growth of solid tumors were reduced in Cd27-deficient mice or in wild-type mice treated with monoclonal antibody to block CD27 signaling. Our findings, therefore, provide a novel mechanism by which the adaptive immune system enhances tumor growth and may offer an attractive strategy to treat solid tumors.
View details for DOI 10.1158/0008-5472.CAN-11-2791
View details for Web of Science ID 000307353200023
View details for PubMedID 22628427
Chronic myelogenous leukemia (CML) results from a chromosomal translocation in hematopoietic stem or early progenitor cells that gives rise to the oncogenic BCR/ABL fusion protein. Clinically, CML has a chronic phase that eventually evolves into an accelerated stage and blast crisis. A CML-specific immune response is thought to contribute to the control of disease. Whether the immune system can also promote disease progression is not known. In the present study, we investigated the possibility that the TNF receptor family member CD27 is present on leukemia stem cells (LSCs) and mediates effects of the immune system on CML. In a mouse model of CML, BCR/ABL+ LSCs and leukemia progenitor cells were found to express CD27. Binding of CD27 by its ligand, CD70, increased expression of Wnt target genes in LSCs by enhancing nuclear localization of active ?-catenin and TRAF2- and NCK-interacting kinase (TNIK). This resulted in increased proliferation and differentiation of LSCs. Blocking CD27 signaling in LSCs delayed disease progression and prolonged survival. Furthermore, CD27 was expressed on CML stem/progenitor cells in the bone marrow of CML patients, and CD27 signaling promoted growth of BCR/ABL+ human leukemia cells by activating the Wnt pathway. Since expression of CD70 is limited to activated lymphocytes and dendritic cells, our results reveal a mechanism by which adaptive immunity contributes to leukemia progression. In addition, targeting CD27 on LSCs may represent an attractive therapeutic approach to blocking the Wnt/?-catenin pathway in CML.
View details for DOI 10.1172/JCI45977
View details for Web of Science ID 000299765800029
View details for PubMedID 22232214
View details for PubMedCentralID PMC3266773
Immune responses have the important function of host defense and protection against pathogens. However, the immune response also causes inflammation and host tissue injury, termed immunopathology. For example, hepatitis B and C virus infection in humans cause immunopathological sequel with destruction of liver cells by the host's own immune response. Similarly, after infection with lymphocytic choriomeningitis virus (LCMV) in mice, the adaptive immune response causes liver cell damage, choriomeningitis and destruction of lymphoid organ architecture. The immunopathological sequel during LCMV infection has been attributed to cytotoxic CD8(+) T cells. However, we now show that during LCMV infection CD4(+) T cells selectively induced the destruction of splenic marginal zone and caused liver cell damage with elevated serum alanin-transferase (ALT) levels. The destruction of the splenic marginal zone by CD4(+) T cells included the reduction of marginal zone B cells, marginal zone macrophages and marginal zone metallophilic macrophages. Functionally, this resulted in an impaired production of neutralizing antibodies against LCMV. Furthermore, CD4(+) T cells reduced B cells with an IgM(high)IgD(low) phenotype (transitional stage 1 and 2, marginal zone B cells), whereas other B cell subtypes such as follicular type 1 and 2 and germinal center/memory B cells were not affected. Adoptive transfer of CD4(+) T cells lacking different important effector cytokines and cytolytic pathways such as IFN?, TNF?, perforin and Fas-FasL interaction did reveal that these cytolytic pathways are redundant in the induction of immunopathological sequel in spleen. In conclusion, our results define an important role of CD4(+) T cells in the induction of immunopathology in liver and spleen. This includes the CD4(+) T cell mediated destruction of the splenic marginal zone with consecutively impaired protective neutralizing antibody responses.
View details for DOI 10.1371/journal.pone.0024772
View details for Web of Science ID 000295267100008
View details for PubMedID 21966366
View details for PubMedCentralID PMC3179489
Chronic myelogenous leukemia (CML) is a malignant myeloproliferative disease of hematopoietic stem cells. The disease progresses after several years from an initial chronic phase to a blast phase. Leukemia-specific T cells are regularly detected in CML patients and may be involved in the immunological control of the disease. Here, we analyzed the role of leukemia-specific CD8(+) T cells in CML disease control and the mechanism that maintains CD8(+) T-cell immunosurveillance in a retroviral-induced murine CML model. To study antigen-specific immune responses, the glycoprotein of the lymphocytic choriomeningitis virus was used as model leukemia antigen. Leukemia-specific CTL activity was detectable in vivo in CML mice and depletion of CD8(+) T cells rapidly led to disease progression. CML-specific CTL were characterized by the expression of the IL-7 receptor ?-chain. In addition, leukemia cells produced IL-7 that was crucial for the maintenance of leukemia-specific CTL and for disease control. Therefore, CML cells maintain the specific CD8(+) T-cell-mediated immune control by IL-7 secretion. This results in prolonged control of disease and probably contributes to the characteristic chronic phase of the disease.
View details for DOI 10.1002/eji.201040404
View details for Web of Science ID 000283387500010
View details for PubMedID 20836157
Chronic myeloid leukemia (CML) is a malignant myeloproliferative disease with a characteristic chronic phase (cp) of several years before progression to blast crisis (bc). The immune system may contribute to disease control in CML. We analyzed leukemia-specific immune responses in cpCML and bcCML in a retroviral-induced murine CML model. In the presence of cpCML and bcCML expressing the glycoprotein of lymphocytic choriomeningitis virus as a model leukemia antigen, leukemia-specific cytotoxic T lymphocytes (CTLs) became exhausted. They maintained only limited cytotoxic activity, and did not produce interferon-gamma or tumor necrosis factor-alpha or expand after restimulation. CML-specific CTLs were characterized by high expression of programmed death 1 (PD-1), whereas CML cells expressed PD-ligand 1 (PD-L1). Blocking the PD-1/PD-L1 interaction by generating bcCML in PD-1-deficient mice or by repetitive administration of alphaPD-L1 antibody prolonged survival. In addition, we found that PD-1 is up-regulated on CD8(+) T cells from CML patients. Taken together, our results suggest that blocking the PD-1/PD-L1 interaction may restore the function of CML-specific CTLs and may represent a novel therapeutic approach for CML.
View details for DOI 10.1182/blood-2008-09-179697
View details for Web of Science ID 000269380300014
View details for PubMedID 19420358
Chronic myelogenous leukemia (CML) is a malignant myeloproliferative disease arising from a hematopoietic stem cell expressing the BCR/ABL fusion protein. Leukemic and dendritic cells (DCs) develop from the same transformed hematopoietic progenitors. How BCR/ABL interferes with the immunoregulatory function of DCs in vivo is unknown. We analyzed the function of BCR/ABL-expressing DCs in a retroviral-induced murine CML model using the glycoprotein of lymphocytic choriomeningitis virus as a model leukemia antigen. BCR/ABL-expressing DCs were found in bone marrow, thymus, spleen, lymph nodes, and blood of CML mice. They were characterized by a low maturation status and induced only limited expansion of naive and memory cytotoxic T lymphocytes (CTLs). In addition, immunization with in vitro-generated BCR/ABL-expressing DCs induced lower frequencies of specific CTLs than immunization with control DCs. BCR/ABL-expressing DCs preferentially homed to the thymus, whereas only few BCR/ABL-expressing DCs reached the spleen. Our results indicate that BCR/ABL-expressing DCs do not efficiently induce CML-specific T-cell responses resulting from low DC maturation and impaired homing to secondary lymphoid organs. In addition, BCR/ABL-expressing DCs in the thymus may contribute to CML-specific tolerance induction of specific CTLs.
View details for DOI 10.1182/blood-2008-05-156471
View details for Web of Science ID 000265910300031
View details for PubMedID 19252140
Bacteriolytic antibiotics cause the release of bacterial components that augment the host inflammatory response, which in turn contributes to the pathophysiology of brain injury in bacterial meningitis. In the present study, antibiotic therapy with nonbacteriolytic daptomycin was compared with that of bacteriolytic ceftriaxone in experimental pneumococcal meningitis, and the treatments were evaluated for their effects on inflammation and brain injury. Eleven-day-old rats were injected intracisternally with 1.3 x 10(4) +/- 0.5 x 10(4) CFU of Streptococcus pneumoniae serotype 3 and randomized to therapy with ceftriaxone (100 mg/kg of body weight subcutaneously [s.c.]; n = 55) or daptomycin (50 mg/kg s.c.; n = 56) starting at 18 h after infection. The cerebrospinal fluid (CSF) was assessed for bacterial counts, matrix metalloproteinase-9 levels, and tumor necrosis factor alpha levels at different time intervals after infection. Cortical brain damage was evaluated at 40 h after infection. Daptomycin cleared the bacteria more efficiently from the CSF than ceftriaxone within 2 h after the initiation of therapy (log(10) 3.6 +/- 1.0 and log(10) 6.3 +/- 1.4 CFU/ml, respectively; P < 0.02); reduced the inflammatory host reaction, as assessed by the matrix metalloproteinase-9 concentration in CSF 40 h after infection (P < 0.005); and prevented the development of cortical injury (cortical injury present in 0/30 and 7/28 animals, respectively; P < 0.004). Compared to ceftriaxone, daptomycin cleared the bacteria from the CSF more rapidly and caused less CSF inflammation. This combined effect provides an explanation for the observation that daptomycin prevented the development of cortical brain injury in experimental pneumococcal meningitis. Further research is needed to investigate whether nonbacteriolytic antibiotic therapy with daptomycin represents an advantageous alternative over current bacteriolytic antibiotic therapies for the treatment of pneumococcal meningitis.
View details for DOI 10.1128/AAC.01014-06
View details for Web of Science ID 000246991400041
View details for PubMedID 17371820
View details for PubMedCentralID PMC1891377