Role of coagulation cascade peptides in the regulation of fibroblast proliferation.

Fibroblast proliferation and extracellular matrix deposition play a critical role in tissue repair and fibrosis. These functions are thought to be modulated by cytokines and growth factors, but these mechanisms are only partially understood. Tissue injury is associated with blood vessel disruption and the activation of coagulation cascade factors VII, IX, X and II (prothrombin) which result in the cleavage of blood fibrinogen into a haemostatic fibrin clot. In addition, increased levels of active coagulation cascade factors and fibrin deposition are associated with fibrotic diseases of the lung, liver, kidney, heart and vasculature. Recently, thrombin has been shown to promote fibroblast chemotaxis, proliferation and procollagen production in vitro and it has been proposed that it may contribute to tissue repair and fibrosis. Little is known about the cellular effects of the other coagulation cascade factors. The aim of this thesis is to study the effects of coagulation factors VIIa, IXa, Xa and fibrinogen cleavage products on fibroblast proliferation in vitro. This thesis shows that factor Xa is mitogenic for fibroblasts and the kinetics of this effect are equivalent to that of thrombin. Studies with specific inhibitors and antibodies demonstrated that this effect is dependent on its catalytic site, but independent of thrombin generation. Furthermore, this is mediated by platelet-derived growth factor production and autocrine stimulation similarly to thrombin. In contrast, factor IXa and fibrinogen-derived peptides have no effects, but factor VIIa and stimulates proliferation at high concentrations. Further studies of receptor expression, activation and intracellular calcium signalling showed that factor Xa stimulates proliferation via binding to effector cell-protease receptor-1 and the proteolytic activation of protease-activated receptor-1. In conclusion, this thesis demonstrated for the first time that coagulation cascade factors Xa and VIIa are mitogenic for fibroblasts, but not all peptides generated during blood coagulation. Furthermore, the mitogenic effect of factor Xa is mediated by a novel dual receptor system involving binding to effector-cell protease receptor-1 and activation of protease-activated receptor-1. These observations suggest that factor Xa may play a role in the regulation of fibroblast proliferation during normal tissue repair and fibrosis

A motif within the N-terminal domain of TSP-1 specifically promotes the proangiogenic activity of endothelial colony-forming cells

Thrombospondin-1 (TSP-1) gives rise to fragments that have both pro- and anti-angiogenic effects in vitro and in vivo. the TSP-HepI peptide (2.3 kDa), located in the N-terminal domain of TSP-1, has proangiogenic effects on endothelial cells. We have previously shown that TSP-1 itself exhibits a dual effect on endothelial colony-forming cells (ECFC) by enhancing their adhesion through its TSP-HepI fragment while reducing their proliferation and differentiation into vascular tubes (tubulogenesis) in vitro. This effect is likely mediated through CD47 binding to the TSP-1 C-terminal domain. Here we investigated the effect of TSP-HepI peptide on the angiogenic properties of ECFC in vitro and in vivo. TSP-HepI peptide potentiated FGF-2-induced neovascularisation by enhancing ECFC chemotaxis and tubulogenesis in a Matrigel plug assay. ECFC exposure to 20 mu g/mL of TSP-HepI peptide for 18 h enhanced cell migration (p < 0.001 versus VEGF exposure), upregulated alpha 6-integrin expression, and enhanced their cell adhesion to activated endothelium under physiological shear stress conditions at levels comparable to those of SDF-1 alpha. the adhesion enhancement appeared to be mediated by the heparan sulfate proteoglycan (HSPG) syndecan-4, as ECFC adhesion was significantly reduced by a syndecan-4-neutralising antibody. ECFC migration and tubulogenesis were stimulated neither by a TSP-HepI peptide with a modified heparin-binding site (S/TSP-HepI) nor when the glycosaminoglycans (GAGS) moieties were removed from the ECFC surface by enzymatic treatment. Ex vivo TSP-HepI priming could potentially serve to enhance the effectiveness of therapeutic neovascularisation with ECFC. (C) 2012 Elsevier Inc. All rights reserved.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Groupe d'Etude et de Recherches sur l'Hemostase (GEHT)Region Ile-de-France (CORDDIM)Leducq TransAtlantic Network of ExcellenceUniv Estado Rio de Janeiro, Dept Biol Celular, Lab Biol Celula Endotelial & Angiogenese LabAngio, Inst Biol Roberto Alcantara Gomes, BR-20550011 Rio de Janeiro, RJ, BrazilINSERM, U765, Paris, FranceUniv Paris 05, Paris, FranceUniversidade Federal de São Paulo, Escola Paulista Med, Dept Biofis, São Paulo, BrazilUniv Fed Rio de Janeiro, Inst Ciencias Biomed, Rio de Janeiro, RJ, BrazilHop Europeen Georges Pompidou, AP HP, Dept Haematol, Paris, FranceINSERM, Paris Cardiovasc Res Ctr, U970, Paris, FranceUniversidade Federal de São Paulo, Escola Paulista Med, Dept Biofis, São Paulo, BrazilLeducq TransAtlantic Network of Excellence: 04CVD01-LENALeducq TransAtlantic Network of Excellence: 04CVD02 -LINATCNPq: E-26/110.780/2010CAPES: 629/09Web of Scienc

J Clin Invest

Arterial cardiovascular events are the leading cause of death in patients with JAK2V617F myeloproliferative neoplasms (MPN). However, their mechanisms are poorly understood. The high prevalence of myocardial infarction without significant coronary stenosis or atherosclerosis in patients with MPN suggests that vascular function is altered. Consequences of JAK2V617F mutation on vascular reactivity are unknown. We observe here increased responses to vasoconstrictors in arteries from Jak2V617F mice, resulting from disturbed endothelial nitric oxide pathway and increased endothelial oxidative stress. This response was reproduced in wild-type mice by circulating microvesicles isolated from patients carrying JAK2V617F and by erythrocyte-derived microvesicles from transgenic mice. Microvesicles of other cellular origins had no effect. This effect was observed ex vivo on isolated aortas, but also in vivo on femoral arteries. Proteomic analysis of microvesicles derived from JAK2V617F erythrocytes identified increased expression of myeloperoxidase as the likely mechanism accounting for microvesicles effect. Myeloperoxidase inhibition in microvesicles derived from JAK2V617F erythrocytes supressed their effect on oxidative stress. Antioxidants, such as simvastatin and N-acetyl-cysteine, improved arterial dysfunction in Jak2V617F mice. In conclusion, JAK2V617F MPN are characterized by exacerbated vasoconstrictor responses resulting from increased endothelial oxidative stress caused by circulating erythrocyte-derived microvesicles. Simvastatin appears as promising therapeutic strategy in this setting

Microvesicles in vascular homeostasis and diseases. Position Paper of the European Society of Cardiology (ESC) Working Group on Atherosclerosis and Vascular Biology

Microvesicles are members of the family of extracellular vesicles shed from the plasma membrane of activated or apoptotic cells. Microvesicles were initially characterised by their pro-coagulant activity and described as "microparticles". There is mounting evidence revealing a role for microvesicles in intercellular communication, with particular relevance to hemostasis and vascular biology. Coupled with this, the potential of microvesicles as meaningful biomarkers is under intense investigation. This Position Paper will summarise the current knowledge on the mechanisms of formation and composition of microvesicles of endothelial, platelet, red blood cell and leukocyte origin. This paper will also review and discuss the different methods used for their analysis and quantification, will underline the potential biological roles of these vesicles with respect to vascular homeostasis and thrombosis and define important themes for future research

Rôle de la thrombospondine-1 dans la génération de microparticules plasmatiques (implication dans le recrutement leucocytaire lors de la thrombose et dans les crises vaso-occlusives drépanocytaires)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Rôle des facteurs plaquettaires de la thrombose et des adipokines dans la thérapie cellulaire pro-angiogénique

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Therapeutic targeting of the survivin pathway in cancer: initiation of mitochondrial apoptosis and suppression of tumor-associated angiogenesis

PURPOSE: Molecular antagonists of the inhibitor of apoptosis protein survivin have shown promise as novel anticancer strategies for triggering tumor cell apoptosis, dysregulating mitotic progression, and inhibiting tumor growth in preclinical models. However, how survivin couples to the cell death machinery has remained elusive, and the relevant cellular targets of survivin antagonists have not been completely elucidated. Experimental Design: Human umbilical vein and dermal microvascular endothelial cells were infected with replication-deficient adenoviruses encoding survivin (pAd-Survivin), green fluorescent protein (pAd-GFP), or a phosphorylation-defective survivin Thr(34)--\u3eAla (pAd-T34A) dominant negative mutant. The effect of wild-type or mutant survivin was investigated on capillary network stability, endothelial cell viability, and caspase activation in vitro and on kinetics of tumor growth and development of angiogenesis in a breast cancer xenograft model in vivo. The cell death pathway initiated by survivin targeting was mapped with respect to cytochrome c release, changes in mitochondrial transmembrane potential, and apoptosome requirements using mouse embryonic fibroblasts deficient in Apaf-1 or caspase-9. RESULTS: Adenoviral transduction of endothelial cells with pAd-Survivin inhibited growth factor deprivation- or ceramide-induced apoptosis, reduced caspase-3 and -7 generation, and stabilized three-dimensional capillary networks in vitro. Conversely, expression of pAd-T34A caused apoptosis in umbilical vein and dermal microvascular endothelial cells and resulted in caspase-3 activity. Cell death induced by survivin targeting exhibited the hallmarks of mitochondrial-dependent apoptosis with release of cytochrome c and loss of mitochondrial transmembrane potential and was suppressed in Apaf-1 or caspase-9 knockout mouse embryonic fibroblasts. When injected in human breast cancer xenografts, pAd-T34A inhibited growth of established tumors and triggered tumor cell apoptosis in vivo. This was associated with a approximately 60% reduction in tumor-derived blood vessels by quantitative morphometry of CD31-stained tumor areas, and appearance of endothelial cell apoptosis by internucleosomal DNA fragmentation in vivo. CONCLUSIONS: Survivin functions as a novel upstream regulator of mitochondrial-dependent apoptosis, and molecular targeting of this pathway results in anticancer activity via a dual mechanism of induction of tumor cell apoptosis and suppression of angiogenesis

Mesenchymal stem cells-derived exosomes are more immunosuppressive than microparticles in inflammatory arthritis

International audienceObjectives: Mesenchymal stem cells (MSCs) release extracellular vesicles (EVs) that display a therapeutic effect in inflammatory disease models. Although MSCs can prevent arthritis, the role of MSCs-derived EVs has never been reported in rheumatoid arthritis. This prompted us to compare the function of exosomes (Exos) and microparticles (MPs) isolated from MSCs and investigate their immunomodulatory function in arthritis. Methods: MSCs-derived Exos and MPs were isolated by differential ultracentrifugation. Immunosuppressive effects of MPs or Exos were investigated on T and B lymphocytes in vitro and in the Delayed-Type Hypersensitivity (DTH) and Collagen-Induced Arthritis (CIA) models. Results: Exos and MPs from MSCs inhibited T lymphocyte proliferation in a dose-dependent manner and decreased the percentage of CD4 + and CD8 + T cell subsets. Interestingly, Exos increased Treg cell populations while parental MSCs did not. Conversely, plasmablast differentiation was reduced to a similar extent by MSCs, Exos or MPs. IFN-γ priming of MSCs before vesicles isolation did not influence the immunomodulatory function of isolated Exos or MPs. In DTH, we observed a dose-dependent anti-inflammatory effect of MPs and Exos, while in the CIA model, Exos efficiently decreased clinical signs of inflammation. The beneficial effect of Exos was associated with fewer plasmablasts and more Breg-like cells in lymph nodes. Conclusions: Both MSCs-derived MPs and Exos exerted an anti-inflammatory role on T and B lymphocytes independently of MSCs priming. However, Exos were more efficient in suppressing inflammation in vivo. Our work is the first demonstration of the therapeutic potential of MSCs-derived EVs in inflammatory arthritis