Human Muscle Progenitor Cells Displayed Immunosuppressive Effect through Galectin-1 and Semaphorin-3A

In human skeletal muscle, myoblasts represent the main population of myogenic progenitors. We previously showed that, beside their myogenic differentiation capacities, myoblasts also differentiate towards osteogenic and chondrogenic lineages, some properties generally considered being hallmarks of mesenchymal stem cells (MSCs). MSCs are also characterized by their immunosuppressive potential, through cell-cell contacts and soluble factors, including prostaglandin E-2 (PGE-2), transforming growth factor-β1 (TGF-β1), interleukine-10, or indoleamine 2,3-dioxygenase. We and others also reported that Galectin-1 (Gal-1) and Semaphorin-3A (Sema-3A) were involved in MSCs-mediated immunosuppression. Here, we show that human myoblasts induce a significant and dose-dependant proliferation inhibition, independently of PGE-2 and TGF-β1. Our experiments revealed that myoblasts, in culture or in situ in human muscles, expressed and secreted Gal-1 and Sema-3A. Furthermore, myoblasts immunosuppressive functions were reverted by using blocking antibodies against Gal-1 or Sema-3A. Together, these results demonstrate an unsuspected immunosuppressive effect of myoblasts that may open new therapeutic perspectives

Cellules souches mésenchymateuses (procédé de thérapie cellulaire et applications cliniques)

PARIS-BIUP (751062107) / SudocSudocFranceF

Intérêt des retinoïdes dans le traitement différenciateur des cancers thyroïdiens en impasse thérapeutique (résultats cliniques et étude in vitro)

Au cours de leur évolution tumorale, certains cancers thyroïdiens différenciés (CTD) perdent leur capacité à fixer l'iode en raison d'une dé-différenciation cellulaire. Ces patients se trouvent alors en impasse thérapeutique puisque l'iode radioactif, seul traitement de ces cancers, devient inefficace. Les résultats de notre étude clinique démontrent l'intérêt d'une thérapeutique différenciatrice par rétinoïdes puisqu'une ré-induction de la fixation de l'iode a été observée chez 37 % des patients traités par l'acide rétinoïque 13-cis (AR 13-cis). Nous avons également mis en évidence une efficacité du bexarotène chez certains patients résistants à l'AR 13-cis. Cependant, l'effet sur la réponse tumorale a été très variable, parfois même variable selon les sites tumoraux chez un même patient, et cela indépendamment ou non de la fixation de l'iode et de la réponse du marqueur tumoral, la thyroglobuline. Afin de déterminer les facteurs moléculaires prédictifs d'une réponse à l'acide rétinoïque (AR), nous avons étudié l'effet de différents rétinoïdes sur la différenciation de deux lignées de cancers folliculaires de la thyroïde présentant des sensibilités distinctes à l'AR. L'AR tout-trans (ATRA) induit l'expression de gènes spécifiques des fonctions thyroïdiennes uniquement dans la lignée FTC133. L'étude de l'expression des récepteurs nucléaires à l'AR (RAR et RXR) montre une faible expression de l'isoforme RARb dans les deux lignées. Alors que le traitement par l'ATRA restaure l'expression de RARb dans la lignée sensible FTC133, seul un traitement par l'AR 13-cis ou le béxarotène, analogue spécifique de RXR, permet de lever cette inhibition dans la lignée FTC238. Ces résultats suggèrent que l'effet des rétinoïdes dans la différenciation des CTD dépend de la structure du rétinoïde et est lié à l'expression différentielle des RAR et RXR endogènes ainsi que de leur induction par l'AR. Une thérapeutique différenciatrice semble ainsi une stratégie prometteuse. Cependant, un ciblage des tumeurs et/ou des patients susceptibles de pouvoir en bénéficier est nécessaire.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Résistance des cellules tumorales aux rétinoïdes (paramètres moléculaires prédictifs d'une réponse thérapeutique aux rexinoïdes et aux drogues épigénétiques)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Human Bone Marrow Mesenchymal Stem Cells Regulate Biased DNA Segregation in Response to Cell Adhesion Asymmetry

Biased DNA segregation is a mitotic event in which the chromatids carrying the original template DNA strands and those carrying the template copies are not segregated randomly into the two daughter cells. Biased segregation has been observed in several cell types, but not in human mesenchymal stem cells (hMSCs), and the factors affecting this bias have yet to be identified. Here, we have investigated cell adhesion geometries as a potential parameter by plating hMSCs from healthy donors on fibronectin-coated micropatterns. On symmetric micropatterns, the segregation of sister chromatids to the daughter cells appeared random. In contrast, on asymmetric micropatterns, the segregation was biased. This sensitivity to asymmetric extracellular cues was reproducible in cells from all donors but was not observed in human skin-derived fibroblasts or in a fibroblastic cell line used as controls. We conclude that the asymmetry of cell adhesion is a major factor in the regulation of biased DNA segregation in hMSCs

Non-Classical HLA Determinants of the Clinical Response after Autologous Stem Cell Transplantation for Systemic Sclerosis

International audienceSystemic Sclerosis (SSc) is a chronic autoimmune disease with high morbidity and mortality. Autologous Hematopoietic Stem Cell Transplantation (AHSCT) is the best therapeutic option for rapidly progressive SSc, allowing increased survival with regression of skin and lung fibrosis. The immune determinants of the clinical response after AHSCT have yet to be well characterized. In particular, the pivotal role of the Human Leukocyte Antigen (HLA) system is not well understood, including the role of non-classical immuno-modulatory HLA-E and HLA-G molecules in developing tolerance and the role of Natural Killer cells (NK) in the immunomodulation processes. We retrospectively tested whether the genetic and/or circulating expression of the non-classical HLA-E and HLA-G loci, as well as the imputed classical HLA determinants of HLA-E expression, influence the observed clinical response to AHSCT at 12- and 24-month follow-up. In a phenotypically well-defined sample of 46 SSc patients classified as clinical responders or non-responders, we performed HLA genotyping using next-generation sequencing and circulating levels of HLA-G and quantified HLA-E soluble isoforms by ELISA. The -21HLA-B leader peptide dimorphism and the differential expression level of HLA-A and HLA-C alleles were imputed. We observed a strong trend towards better clinical response in HLA-E*01:03 or HLA-G 14bp Del allele carriers, which are known to be associated with high expression of the corresponding molecules. At 12-month post-AHSCT follow-up, higher circulating levels of soluble HLA-E were associated with higher values of modified Rodnan Skin Score (mRSS) (p = 0.0275), a proxy of disease severity. In the non-responder group, the majority of patients carried a double dose of the HLA-B Threonine leader peptide, suggesting a non-efficient inhibitory effect of the HLA-E molecules. We did not find any correlation between the soluble HLA-G levels and the observed clinical response after AHSCT. High imputed expression levels of HLA-C alleles, reflecting more efficient NK cell inhibition, correlated with low values of the mRSS 3 months after AHSCT (p = 0.0087). This first pilot analysis of HLA-E and HLA-G immuno-modulatory molecules suggests that efficient inhibition of NK cells contributes to clinical response after AHSCT for SSc. Further studies are warranted in larger patient cohorts to confirm our results

Identification des microvésicules génératrices de plasmine : De minuscules messagers impliqués dans la fibrinolyse et la protéolyse

International audienceA number of stressors and inflammatory mediators (cytokines, proteases, oxidative stress mediators) released during inflammation or ischemia stimulate and activate cells in blood, the vessel wall or tissues. The most well-known functional and phenotypic responses of activated cells are (1) the immediate expression and/or release of stored or newly synthesized bioactive molecules, and (2) membrane blebbing followed by release of microvesicles. An ultimate response, namely the formation of extracellular traps by neutrophils (NETs), is outside the scope of this work. The main objective of this article is to provide an overview on the mechanism of plasminogen reception and activation at the surface of cell-derived microvesicles, new actors in fibrinolysis and proteolysis. The role of microvesicle-bound plasmin in pathological settings involving inflammation, atherosclerosis, angiogenesis, and tumour growth, remains to be investigated. Further studies are necessary to determine if profibrinolytic microvesicles are involved in a finely regulated equilibrium with pro-coagulant microvesicles, which ensures a balanced haemostasis, leading to the maintenance of vascular patency.Un certain nombre de facteurs de stress et de médiateurs inflammatoires (cytokines, protéases, médiateurs du stress oxydatif) libérés pendant l'inflammation ou l'ischémie stimulent et activent les cellules du sang, de la paroi vasculaire ou des tissus. Les réponses fonctionnelles et phénotypiques les plus connues des cellules activées sont (1) l'expression et/ou la libération immédiate de molécules bioactives stockées ou nouvellement synthétisées, et (2) le décollement de la membrane suivi de la libération de microvésicules. Une réponse ultime, à savoir la formation de pièges extracellulaires par les neutrophiles (NETs), sort du cadre de ce travail. L'objectif principal de cet article est de donner un aperçu du mécanisme de réception et d'activation du plasminogène à la surface des microvésicules dérivées des cellules, nouveaux acteurs de la fibrinolyse et de la protéolyse. Le rôle de la plasmine liée aux microvésicules dans des contextes pathologiques impliquant l'inflammation, l'athérosclérose, l'angiogenèse et la croissance tumorale, reste à étudier. D'autres études sont nécessaires pour déterminer si les microvésicules profibrinolytiques sont impliquées dans un équilibre finement régulé avec les microvésicules pro-coagulantes, qui assure une hémostase équilibrée, conduisant au maintien de la perméabilité vasculaire

Bone Marrow Microenvironment in an In Vitro Model of Gaucher Disease: Consequences of Glucocerebrosidase Deficiency

International audienc

Regulatory B Cells Contribute to the Clinical Response After Bone Marrow-Derived Mesenchymal Stromal Cell Infusion in Patients With Systemic Sclerosis

International audiencecenter dot Initial overexpression of profibrotic factors by B cells is associated with a lack of clinical response to mesenchymal stromal cells (MSCs) in patients with severe systemic sclerosis (SSc). center dot Increase of regulatory B cells is a marker of clinical response to MSCs in SSc patients. center dot MSCs directly upregulate IL-10 production by activated B cells in vitro. Mesenchymal stromal cells (MSCs) have recently emerged as an interesting therapeutic approach for patients with progressive systemic sclerosis (SSc), a rare and life-threatening orphan autoimmune disease. Whereas MSC immunomodulatory potential is considered as a central mechanism for their clinical benefit, very few data are available on the impact of MSCs on immune cell subsets in vivo. In the current extended study of a phase I/II clinical trial exploring the injection of a single dose of allogeneic bone marrow-MSCs (alloBM-MSCs) in patients with severe SSc (NCT02213705), we performed a longitudinal in-depth characterization of circulating immune cells in 19 MSC-treated patients, including 14 responders and 5 non-responders. By a combination of flow cytometry and transcriptomic analyses, we highlighted an increase in circulating CD24(hi)CD27(pos)CD38(lo/neg) memory B cells, the main IL-10-producing regulatory B cell (Breg) subset, and an upregulation of IL10 expression in ex-vivo purified B cells, specifically in responder patients, early after the alloBM-MSC infusion. In addition, a deeper alteration of the B-cell compartment before alloBM-MSC treatment, including a higher expression of profibrotic cytokines IL6 and TGF beta by sorted B cells was associated with a non-responder clinical status. Finally, BM-MSCs were able to directly upregulate IL-10 production in activated B cells in vitro. These data suggest that cytokine-producing B cells, in particular Breg, are pivotal effectors of BM-MSC therapeutic activity in SSc. Their quantification as activity biomarkers in MSC potency assays and patient selection criteria may be considered to reach optimal clinical benefit when designing MSC-based clinical trials