Meirav Pevsner-Fischer

Weizmann Institute of Science, Rhovot, Central District, Israel

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Publications (26)210.99 Total impact

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    [Show abstract] [Hide abstract] ABSTRACT: "The forgotten organ", the human microbiome, comprises a community of microorganisms that colonizes various sites of the human body. Through coevolution of bacteria, archaea and fungi with the human host over thousands of years, a complex host-microbiome relationship emerged in which many functions, including metabolism and immune responses, became codependent. This coupling becomes evident when disruption in the microbiome composition, termed dysbiosis, is mirrored by the development of pathologies in the host. Among the most serious consequences of dysbiosis, is the development of cancer. As many as 20% of total cancers worldwide are caused by a microbial agent. To date, a vast majority of microbiome-cancer studies focus solely on the microbiome of the large intestine and the development of gastrointestinal cancers. Here, we will review the available evidence implicating microbiome involvement in the development and progression of non-gastrointestinal cancers, while distinguishing between viral and bacterial drivers of cancer, as well as "local" and "systemic", "cancer-stimulating" and "cancer-suppressing" effects of the microbiome. Developing a system-wide approach to cancer-microbiome studies will be crucial in understanding how microbiome influences carcinogenesis, and may enable to employ microbiome-targeting approaches as part of cancer treatment.
    Preview · Article · Apr 2016
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    [Show abstract] [Hide abstract] ABSTRACT: Summary Host-microbiome co-evolution drives homeostasis and disease susceptibility, yet regulatory principles governing the integrated intestinal host-commensal microenvironment remain obscure. While inflammasome signaling participates in these interactions, its activators and microbiome-modulating mechanisms are unknown. Here, we demonstrate that the microbiota-associated metabolites taurine, histamine, and spermine shape the host-microbiome interface by co-modulating NLRP6 inflammasome signaling, epithelial IL-18 secretion, and downstream anti-microbial peptide (AMP) profiles. Distortion of this balanced AMP landscape by inflammasome deficiency drives dysbiosis development. Upon fecal transfer, colitis-inducing microbiota hijacks this microenvironment-orchestrating machinery through metabolite-mediated inflammasome suppression, leading to distorted AMP balance favoring its preferential colonization. Restoration of the metabolite-inflammasome-AMP axis reinstates a normal microbiota and ameliorates colitis. Together, we identify microbial modulators of the NLRP6 inflammasome and highlight mechanisms by which microbiome-host interactions cooperatively drive microbial community stability through metabolite-mediated innate immune modulation. Therefore, targeted "postbiotic" metabolomic intervention may restore a normal microenvironment as treatment or prevention of dysbiosis-driven diseases.
    Full-text · Article · Dec 2015 · Cell
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    [Show abstract] [Hide abstract] ABSTRACT: Elevated postprandial blood glucose levels constitute a global epidemic and a major risk factor for prediabetes and type II diabetes, but existing dietary methods for controlling them have limited efficacy. Here, we continuously monitored week-long glucose levels in an 800-person cohort, measured responses to 46,898 meals, and found high variability in the response to identical meals, suggesting that universal dietary recommendations may have limited utility. We devised a machine-learning algorithm that integrates blood parameters, dietary habits, anthropometrics, physical activity, and gut microbiota measured in this cohort and showed that it accurately predicts personalized postprandial glycemic response to real-life meals. We validated these predictions in an independent 100-person cohort. Finally, a blinded randomized controlled dietary intervention based on this algorithm resulted in significantly lower postprandial responses and consistent alterations to gut microbiota configuration. Together, our results suggest that personalized diets may successfully modify elevated postprandial blood glucose and its metabolic consequences. VIDEO ABSTRACT.
    Full-text · Article · Nov 2015 · Cell
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    [Show abstract] [Hide abstract] ABSTRACT: Metagenomic sequencing increased our understanding of the role of the microbiome in health and disease, yet it only provides a snapshot of a highly dynamic ecosystem. Here, we show that the pattern of metagenomic sequencing read coverage for different microbial genomes contains a single trough and a single peak, the latter coinciding with the bacterial origin of replication. Furthermore, the ratio of sequencing coverage between the peak and trough provides a quantitative measure of a species’ growth rate. We demonstrate this in vitro and in vivo, under different growth conditions, and in complex bacterial communities. For several bacterial species, peak-to-trough coverage ratios, but not relative abundances, correlated with the manifestation of inflammatory bowel disease and type II diabetes.
    Full-text · Article · Sep 2015 · Science
  • Ada Weinstock · Meirav Pevsner-Fischer · Ziv Porat · Michael Selitrennik · Dov Zipori
    [Show abstract] [Hide abstract] ABSTRACT: Mesenchymal stem cells (MSCs) serve as supporting and regulatory cells, by providing tissues with multiple factors and are also known for their immunosuppressive capabilities. Our laboratory had previously shown that MSCs expressed toll-like receptor (TLR) 2 and are activated by its ligand Pam3Cys. TLR2 is an important component of the innate immune system, as it recognizes bacterial lipopeptides, thus priming a pro-inflammatory immune response. This study showed that Pam3Cys attached extensively to cells of both wild-type and TLR2 deficient cultured MSCs, thus, independently of TLR2. The TLR2 independent binding occurred through the adsorption of the palmitoyl moieties of Pam3Cys. It was further showed that Pam3Cys was transferred from cultured MSCs to immune cells. Moreover, Pam3Cys provided to the immune cells induced a pro-inflammatory response in vitro and in vivo. Overall, it is demonstrated herein that a TLR2 ligand bound to MSCs also through a TLR2 independent mechanism. Furthermore, the ligand incorporated by MSCs is subsequently released to stimulate an immune response both in vitro and in vivo. It is thus suggested that during bacterial infection, stromal cells may retain a reservoir of the TLR2 ligands, in a long-term manner, and release them slowly to maintain an immune response.
    No preview · Article · Aug 2015 · Stem cell reviews
  • [Show abstract] [Hide abstract] ABSTRACT: The outstanding heterogeneity of stem cell populations is a major obstacle on the way to their clinical application. It is therefore paramount to identify the molecular mechanisms that underlay this heterogeneity. Individually derived bone marrow mesenchymal stromal cells (MSCs) preparations, studied here, diverged markedly in various properties, despite of being all tripotent in their differentiation potential. Microarray analysis showed that MSC diversity is evident also in highly variable gene expression patterns. Differentially expressed genes were significantly enriched in toll-like receptors (TLRs) and differentiation pathways. Marked differences were observed in LPS binding protein (LBP) and transforming growth factor (TGF)β1 expression. These differences correlated with MSC functionality. Therefore, the possible contribution of these molecules to MSC diversity was examined. In the TLR signaling pathway, LBP levels predicted the ability of specific MSCs to secrete interleukin (IL)-6 in response to LPS. A relatively higher expression of TGFβ1 endowed MSCs with a capacity to respond to IL-1β by reduced osteogenic differentiation. This study thus demonstrates major diversity within MSC isolates, which appears early on following derivation and persists following long-term culture. MSC heterogeneity results from highly variable transcriptome. Differential expression of LBP and TGFβ1, along with other genes, in different MSC preparations, produces the variable responses to external stimuli.
    No preview · Article · Mar 2014 · Stem cell reviews
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    [Show abstract] [Hide abstract] ABSTRACT: Human mesenchymal stromal cells (hMSCs) from adipose cardiac tissue have attracted considerable interest in regard to cell-based therapies. We aimed to test the hypothesis that hMSCs from the heart and epicardial fat would be better cells for infarct repair. We isolated and grew hMSCs from patients with ischemic heart disease from 4 locations: epicardial fat, pericardial fat, subcutaneous fat, and the right atrium. Significantly, hMSCs from the right atrium and epicardial fat secreted the highest amounts of trophic and inflammatory cytokines, while hMSCs from pericardial and subcutaneous fat secreted the lowest. Relative expression of inflammation- and fibrosis-related genes was considerably higher in hMSCs from the right atrium and epicardial fat than in subcutaneous fat hMSCs. To determine the functional effects of hMSCs, we allocated rats to hMSC transplantation 7 days after myocardial infarction. Atrial hMSCs induced greatest infarct vascularization as well as highest inflammation score 27 days after transplantation. Surprisingly, cardiac dysfunction was worst after transplantation of hMSCs from atrium and epicardial fat and minimal after transplantation of hMSCs from subcutaneous fat. These findings were confirmed by using hMSC transplantation in immunocompromised mice after myocardial infarction. Notably, there was a correlation between tumor necrosis factor-α secretion from hMSCs and posttransplantation left ventricular remodeling and dysfunction. Because of their proinflammatory properties, hMSCs from the right atrium and epicardial fat of cardiac patients could impair heart function after myocardial infarction. Our findings might be relevant to autologous mesenchymal stromal cell therapy and development and progression of ischemic heart disease.
    Full-text · Article · Aug 2013 · Journal of the American Heart Association
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    Noam Cohen · Raanan Margalit · Meirav Pevsner-Fischer · Simon Yona · Steffen Jung · Lea Eisenbach · Irun R Cohen
    [Show abstract] [Hide abstract] ABSTRACT: Mice are exceedingly sensitive to intra-peritoneal (IP) challenge with some virulent pneumococci (LD50 = 1 bacterium). To investigate how peripheral contact with bacterial capsular polysaccharide (PS) antigen can induce resistance, we pulsed bone marrow dendritic cells (BMDC) of C57BL/6 mice with type 4 or type 3 PS, injected the BMDC intra-foot pad (IFP) and challenged the mice IP with supra-lethal doses of pneumococci. We examined the responses of T cells and B cells in the draining popliteal lymph node and measured the effects on the bacteria in the peritoneum and blood. We now report that: 1) The PS co-localized with MHC molecules on the BMDC surface; 2) PS-specific T and B cell proliferation and IFNγ secretion was detected in the draining popliteal lymph nodes on day 4; 3) Type-specific resistance to lethal IP challenge was manifested only after day 5; 4) Type-specific IgM and IgG antibodies were detected in the sera of only some of the mice, but B cells were essential for resistance; 5) Control mice vaccinated with a single injection of soluble PS did not develop a response in the draining popliteal lymph node and were not protected; 6) Mice injected with unpulsed BMDC also did not resist challenge: In unprotected mice, pneumococci entered the blood shortly after IP inoculation and multiplied exponentially in both blood and peritoneum killing the mice within 20 hours. Mice vaccinated with PS-pulsed BMDC trapped the bacteria in the peritoneum. The trapped bacteria proliferated exponentially IP, but died suddenly at 18-20 hours. Thus, a single injection of PS antigen associated with intact BMDC is a more effective vaccine than the soluble PS alone. This model system provides a platform for studying novel aspects of PS-targeted vaccination.
    Full-text · Article · Jun 2012 · PLoS ONE
  • Meirav Pevsner-Fischer · Sarit Levin · Dov Zipori
    [Show abstract] [Hide abstract] ABSTRACT: Cultured mesenchymal stromal cell (MSC) populations are best characterized by the capacity of some cells within this population to differentiate into mesodermal derivatives such as osteoblasts, chondrocytes and adipocytes. However, this progenitor property is not shared by all cells within the MSC population. Furthermore, MSCs exhibit variability in their phenotypes, including proliferation capacity, expression of cell surface markers and ability to secrete cytokines. These facts raise three major questions: (1) Does the in vitro observed variability reflect the existence of MSC subsets in vivo? (2) What is the molecular basis of the in vitro observed heterogeneity? and (3) What is the biological significance of this variability? This review considers the possibility that the variable nature of MSC populations contributes to the capacity of adult mammalian tissues to adapt to varying microenvironmental demands.
    No preview · Article · Sep 2011 · Stem cell reviews
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    [Show abstract] [Hide abstract] ABSTRACT: In human multiple myeloma (MM), the tumor cells exhibit strict dependence on bone marrow (BM) stromal elements. It has been suggested that, in turn, MM cells modify multipotent stromal cells (MSCs), diverting them to support the myeloma. We investigated MM-derived MSCs by comparing their toll-like receptor (TLR) responses to those of MSCs derived from healthy controls. We now report that MM-derived MSCs manifested intact proliferation responses and IL-6 secretion and their adipose and osteogenic differentiation responses to TLR ligands were also similar to those of healthy controls, ranging from augmentation to inhibition. However, MM-derived MSCs were found to be defective in IL-8 secretion and ERK1/2 phosphorylation following TLR-2 activation. Moreover, MM-derived MSCs failed to respond to EGF by elevation of ERK1/2 phosphorylation. The persistence of these changes in extensively cultured MM-derived MSCs, suggests that these cells are stably, if not irreversibly modified.
    Full-text · Article · Sep 2011 · Stem cell reviews
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    David Margel · Meirav Pevsner-Fischer · Jack Baniel · Ofer Yossepowitch · Irun R. Cohen
    Full-text · Article · Apr 2011 · European Urology
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    [Show abstract] [Hide abstract] ABSTRACT: Cancer often involves inflammatory processes. We hypothesized that immune mediators in urine may serve as biomarkers for bladder cancer (BCa). To investigate whether BCa might be marked by urinary levels of heat shock proteins (HSPs; HSP60, HSP70, or HSP90) or cytokines (interferon [IFN]-γ, tumor necrosis factor [TNF]-α, tumor growth factor [TGF]-β, interleukin [IL]-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, or IL-13). This was a case-control study with a discovery and validation phase. We examined urine from 106 consecutive patients: healthy controls (n=18); hematuria with no evidence of BCa (n=20); non-muscle-invasive BCa (n=50); and muscle-invasive BCa (n=18). The concentrations of HSPs and cytokines were assessed by enzyme-linked immunosorbent assay. In the validation phase, independent urine samples from 40 patients were analyzed (controls [n=19] and BCa [n=21]). We used the area under the curve (AUC) of a receiver operating characteristic analysis to determine the ability of HSPs and cytokines to mark BCa and applied a multivariate logistic regression to create a formula able to diagnose BCa. The formula was applied to the validation set without recalculation, and positive and negative predictive values were calculated. Urinary concentrations of IL-8, IL-10, and IL-13 were significantly elevated in BCa; IL-13 was the most prominent marker (AUC: 0.93; 95% confidence interval [CI], 0.85-0.99). The multivariate regression analysis highlighted HSP60 (odds ratio [OR]: 1.206; 95% CI, 1.041-1.397, p=0.003) and IL-13 (OR: 1.020; 95% CI: 1.007-1.033, p=0.012). The validation assay was performed using HSP60 and IL-13. The overall positive predictive value was 74% (95% CI, 64-84%); and the negative predictive value was 76% (95% CI, 66-86%). Since we examined a small number of patients, the results need to be confirmed in a larger cohort. These results suggest that it might be possible to develop a urinary biomarker for BCa and raise the possibility that expression of anti-inflammatory cytokines and HSPs might allow BCa to evade immune surveillance.
    Full-text · Article · Oct 2010 · European Urology
  • M. Pevsner-Fischer · S. Levin · T. Hammer · Y. Cohen · F. Mor · M. Mayorov · G. Wagemaker · A. Nagler · I. Cohen · D. Zipori
    No preview · Conference Paper · Jun 2010
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    [Show abstract] [Hide abstract] ABSTRACT: The identification and isolation of human cardiac progenitor cells (hCPCs) offer new approaches for myocardial regeneration and repair. Still, the optimal source of human cardiac progenitor cells and the influence of patient characteristics on their number remain unclear. Using a novel method to isolate human cardiac progenitor cells, we aimed to define the optimal source and association between their number and patient characteristics. We developed a novel isolation method that produced viable cells (7 x 10(6)+/-6.53 x 10(5)/g) from various tissue samples obtained during heart surgery or endomyocardial biopsies (113 samples from 94 patients 23 to 80 years of age). The isolated cardiac cells were grown in culture with a stem cell expansion medium. According to fluorescence-activated cell sorting analysis, cultured cells derived from the right atrium generated higher amounts of c-kit(+) (24+/-2.5%) and Islet-1(+) cells (7%) in culture (mean of passages 1, 2, and 3) than did cultured cells from the left atrium (7.3+/-3.5%), right ventricle (4.1+/-1.6%), and left ventricle (9.7+/-3%; P=0.001). According to multivariable analysis, the right atrium as the cell source and female sex were associated with a higher number of c-kit(+) cells. There was no overlap between c-kit(+) and Islet-1 expression. In vitro assays of differentiation into osteoblasts, adipocytes, and myogenic lineage showed that the isolated human cardiac progenitor cells were multipotent. Finally, the cells were transplanted into infarcted myocardium of rats and generated myocardial grafts. Our results show that the right atrium is the best source for c-kit(+) and Islet-1 progenitors, with higher percentages of c-kit(+) cells being produced by women.
    Preview · Article · Dec 2009 · Circulation
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    Michal Cohen-Sfady · Meirav Pevsner-Fischer · Raanan Margalit · Irun R Cohen
    [Show abstract] [Hide abstract] ABSTRACT: We recently reported that heat shock protein 60 (HSP60) via TLR4 signaling activates B cells and induces them to proliferate and secrete IL-10. We now report that HSP60 inhibits mouse B cell apoptosis, spontaneous or induced by dexamethasone or anti-IgM activation. Unlike HSP60 enhancement of B cell proliferation and IL-10 secretion, TLR4 signaling was not required for the inhibition of apoptosis by HSP60; nevertheless, MyD88 was essential. Inhibition of apoptosis by HSP60 was associated with up-regulation of the antiapoptotic molecules Bcl-2, Bcl-x(L), and survivin, maintenance of the mitochondrial transmembrane potential, and inhibition of caspase-3 activation. Moreover, B cells incubated with HSP60 manifested prolonged survival following transfer into recipient mice. These results extend the varied role of HSP60 in the innate regulation of the adaptive immune response.
    Preview · Article · Jul 2009 · The Journal of Immunology
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    [Show abstract] [Hide abstract] ABSTRACT: Multiple myeloma is characterized by the malignant growth of immunoglobulin producing plasma cells, predominantly in the bone marrow. The effects of primary human mesenchymal stromal cells on the differentiation phenotype of multiple myeloma cells were studied by co-culture experiments. The incubation of multiple myeloma cells with bone marrow-derived mesenchymal stromal cells resulted in significant reduction of the expression of the predominant plasma cell differentiation markers CD38 and CD138, and cell surface immunoglobulin light chain. While the down-regulation of CD138 by stromal cells was completely dependent on their adhesive interactions with the multiple myeloma cells, interleukin-6 induced specific down-regulation of CD38. Mesenchymal stromal cells or their conditioned media inhibited the growth of multiple myeloma cell line, thereby reducing the overall amounts of secreted light chains. Analysis of primary multiple myeloma bone marrow samples reveled that the expression of CD38 on multiple myeloma cells was not affected by adhesive interactions. The ex vivo propagation of primary multiple myeloma cells resulted in significant increase in their differentiation markers. Overall, the data indicate that the bone marrow-derived mesenchymal stromal cells revert multiple myeloma cells to less differentiated phenotype by the combined activities of adhesive interactions and interleukin-6.
    Full-text · Article · Apr 2009 · Experimental Cell Research
  • Meirav Pevsner-Fischer · Dov Zipori
    [Show abstract] [Hide abstract] ABSTRACT: Mesenchymal progenitor cells are widespread in the organism and are implicated in a variety of physiological and pathological processes. As such, these cells should be able to respond to microenvironmental signals. Here we review some of the conditions that modulate the biological functions of mesenchymal progenitors, particularly during inflammation and stress. KeywordsMultipotent stromal cells–Hemopoietic stem cells–Microenvironments–Toll-like receptors–Inflammation–Stress
    No preview · Chapter · Dec 2008
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    Dataset: Figure S1
    [Show abstract] [Hide abstract] ABSTRACT: p53 inhibits the adipogenic differentiation program in the MBA-15 cell line. (A and B) Confluent cultures of MBA-15-sh-p53 and control cells were subjected to induction of adipogenic differentiation by treatment with medium containing 10 µg/ml insulin, 10-6M dexamethasone, 0.5 Mm 3-Isobutyl-1-methylxanthine (Adipogenic medium) or with control medium (non treated, NT). The cells were grown for three weeks with medium replacement once in three days. Total RNA was isolated before to the induction of differentiation (od) as well as 7 and 21 days later. Relative expression of PPARγ, CEBPα, Ap2 and AdipoQ were determined by QRT-PCR analysis. The results of QRT-PCR are presented as a range of two duplicate runs (N = 2) after normalization to HPRT control. (A) Adipogenic differentiation was assessed using Oil Red O staining for lipid droplets (B). (1.57 MB TIF)
    Full-text · Dataset · Nov 2008
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    Dataset: Figure S2
    [Show abstract] [Hide abstract] ABSTRACT: Cells expressing a dominant negative p53 protein display enhanced myofibroblast/smooth muscle differentiation. h-TERT immortalized, early passaged WI-38 cells stably expressing GSE56 (GSE56) or control empty vector (Neo) were grown in culture for 48 hours (non treated, NT); serum starved for 24 hours, and then treated with a fresh serum-free medium with 1 ng/ml TGFβ for 24 h. Relative expression of αSMA, CNN1 and SM-MHC was determined by QRT-PCR. The results of QRT-PCR are presented as a range of two duplicate runs (N = 2) after normalization to GAPDH control. (0.09 MB TIF)
    Full-text · Dataset · Nov 2008
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    [Show abstract] [Hide abstract] ABSTRACT: Cultured bone marrow stromal cells create an in vitro milieu supportive of long-term hemopoiesis and serve as a source for multipotent mesenchymal progenitor cells defined by their ability to differentiate into a variety of mesodermal derivatives. This study aims to examine whether the capacity to support myelopoiesis is coupled with the multipotency. Our results show that the myelopoietic supportive ability of stromal cells, whether from the bone marrow or from embryo origin, is not linked with multipotency; cell populations that possess multipotent capacity may or may not support myelopoiesis, whereas others, lacking multipotency, may possess full myelopoietic supportive ability. However, upon differentiation, the ability of multipotent mesenchymal progenitors to support myelopoiesis is varied. Osteogenic differentiation did not affect myelopoietic supportive capacity, whereas adipogenesis resulted in reduced ability to support the maintenance of myeloid progenitor cells. These differences were accompanied by a divergence in glycosylation patterns, as measured by binding to lectin microarrays; osteogenic differentiation was associated with an increased level of antennarity of N-linked glycans, whereas adipogenic differentiation caused a decrease in antennarity. Inhibition of glycosylation prior to seeding the stroma with bone marrow cells resulted in reduced capacity of the stromal cells to support the formation of cobblestone areas. Our data show that myelopoietic support is unrelated to the multipotent phenotype of cultured mesenchymal progenitors but is dependent on the choice of differentiation pathway and upon correct glycosylation of the stromal cells.
    Preview · Article · Jul 2008 · Stem Cells

Publication Stats

898 Citations
210.99 Total Impact Points

Institutions

  • 2005-2011
    • Weizmann Institute of Science
      • • Department of Molecular Cell Biology
      • • Department of Immunology
      Rhovot, Central District, Israel
  • 2010
    • Rabin Medical Center
      Tell Afif, Tel Aviv, Israel