Longitudinal immunomonitoring following Tocilizumab in rheumatoid arthritis

Poster presentationInternational audienc

Targeted delivery to inflammatory monocytes for efficient RNAi-mediated immuno-intervention in auto-immune arthritis

Poster presentationInternational audienc

Microenvironmental changes during differentiation of mesenchymal stem cells towards chondrocytes

Chondrogenesis is a process involving stem-cell differentiation through the coordinated effects of growth/differentiation factors and extracellular matrix (ECM) components. Recently, mesenchymal stem cells (MSCs) were found within the cartilage, which constitutes a specific niche composed of ECM proteins with unique features. Therefore, we hypothesized that the induction of MSC differentiation towards chondrocytes might be induced and/or influenced by molecules from the microenvironment. Using microarray analysis, we previously identified genes that are regulated during MSC differentiation towards chondrocytes. In this study, we wanted to precisely assess the differential expression of genes associated with the microenvironment using a large-scale real-time PCR assay, according to the simultaneous detection of up to 384 mRNAs in one sample. Chondrogenesis of bone-marrow-derived human MSCs was induced by culture in micropellet for various periods of time. Total RNA was extracted and submitted to quantitative RT-PCR. We identified molecules already known to be involved in attachment and cell migration, including syndecans, glypicans, gelsolin, decorin, fibronectin, and type II, IX and XI collagens. Importantly, we detected the expression of molecules that were not previously associated with MSCs or chondrocytes, namely metalloproteases (MMP-7 and MMP-28), molecules of the connective tissue growth factor (CTGF); cef10/cyr61 and nov (CCN) family (CCN3 and CCN4), chemokines and their receptors chemokine CXC motif ligand (CXCL1), Fms-related tyrosine kinase 3 ligand (FlT3L), chemokine CC motif receptor (CCR3 and CCR4), molecules with A Disintegrin And Metalloproteinase domain (ADAM8, ADAM9, ADAM19, ADAM23, A Disintegrin And Metalloproteinase with thrombospondin type 1 motif ADAMTS-4 and ADAMTS-5), cadherins (4 and 13) and integrins (α4, α7 and β5). Our data suggest that crosstalk between ECM components of the microenvironment and MSCs within the cartilage is responsible for the differentiation of MSCs into chondrocytes

Transcriptional profiles discriminate bone marrow-derived and synovium-derived mesenchymal stem cells

Previous studies have reported that mesenchymal stem cells (MSC) may be isolated from the synovial membrane by the same protocol as that used for synovial fibroblast cultivation, suggesting that MSC correspond to a subset of the adherent cell population, as MSC from the stromal compartment of the bone marrow (BM). The aims of the present study were, first, to better characterize the MSC derived from the synovial membrane and, second, to compare systematically, in parallel, the MSC-containing cell populations isolated from BM and those derived from the synovium, using quantitative assays. Fluorescent-activated cell sorting analysis revealed that both populations were negative for CD14, CD34 and CD45 expression and that both displayed equal levels of CD44, CD73, CD90 and CD105, a phenotype currently known to be characteristic of BM-MSC. Comparable with BM-MSC, such MSC-like cells isolated from the synovial membrane were shown for the first time to suppress the T-cell response in a mixed lymphocyte reaction, and to express the enzyme indoleamine 2,3-dioxygenase activity to the same extent as BM-MSC, which is a possible mediator of this suppressive activity. Using quantitative RT-PCR these data show that MSC-like cells from the synovium and BM may be induced to chondrogenic differentiation and, to a lesser extent, to osteogenic differentiation, but the osteogenic capacities of the synovium-derived MSC were significantly reduced based on the expression of the markers tested (collagen type II and aggrecan or alkaline phosphatase and osteocalcin, respectively). Transcription profiles, determined with the Atlas Human Cytokine/Receptor Array, revealed discrimination between the MSC-like cells from the synovial membrane and the BM-MSC by 46 of 268 genes. In particular, activin A was shown to be one major upregulated factor, highly secreted by BM-MSC. Whether this reflects a different cellular phenotype, a different amount of MSC in the synovium-derived population compared with BM-MSC adherent cell populations or the impact of a different microenvironment remains to be determined. In conclusion, although the BM-derived and synovium-derived MSC shared similar phenotypic and functional properties, both their differentiation capacities and transcriptional profiles permit one to discriminate the cell populations according to their tissue origin

Approche thérapeutique par utilisation de cellules dendritiques tolérogènes et de T régulateurs CD49b+ dans un modèle murin d'arthrite induite au collagène

MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Potentiel thérapeutique des lymphocytes régulateurs de type 1 (Tr1) dans l'arthrite expérimentale.

Objectifs : Les lymphocytes T régulateurs de par leur rôle primordial dans l'homéostasie de la réponse immune sont des cellules idéales pour une immunothérapie antigène-spécifique dans les maladies auto-immunes. Les lymphocytes T régulateurs de type 1 ou Tr1 sont caractérisées par une forte sécrétion d'IL-10, cytokine qui joue un rôle déterminant dans leur capacité à supprimer des réponses immunes pathologiques dans différents contextes. L'objectif de ma thèse est d'évaluer le potentiel thérapeutique de cellules Tr1 spécifiques du collagène de type II (col-Treg) dans deux modèles de polyarthrite rhumatoïde (PR) chez la souris. Méthode : Les clones Col-Treg ne possèdent pas de marqueurs membranaires spécifiques mais sont caractérisés par un profil cytokinique particulier (IL10highIL4negIFN-gint) et par leur capacité de suppression in vitro. Tout comme les Tregs naturels, ils expriment une quantité importante de GITR, de CD39 et de Granzyme B. Une simple injection de cellules Col-Treg réduit l'incidence et les symptômes cliniques de l'arthrite à la fois de manière préventive et curative, avec un impact significatif sur les anticorps anti-collagène de type II. En outre, l'injection de Tr1 antigène spécifique in vivo diminue de manière significative la prolifération des cellules T antigène spécifique. Conclusion : Nos résultats démontrent le potentiel thérapeutique des cellules Col-Treg dans deux modèles d'arthrite expérimentale prouvant que les cellules Col-Treg représente une nouvelle approche thérapeutique de choix pour le traitement des patients atteint de polyarthrite et réfractaires aux traitements actuels.Objectives : Regulatory T (Treg) cells play a crucial role in preventing autoimmune diseases and are an ideal target for therapies to suppress inflammation in an antigen-specific manner. Type 1 Treg cells (Tr1) are defined by their capacity to produce high levels of IL10, which contributes to their ability to suppress pathological immune responses in several settings. The aim of my PhD was to evaluate the therapeutic potential of collagen type II-specific Tr1 (Col-Treg) cells in two models of rheumatoid arthritis (RA) in mice. Methods : Col-Treg clones were isolated and expanded from Collagen-specific TCR transgenic mice. Their cytokine secretion profile and phenotype characterization were studied. The therapeutic potential of Col-Treg cells was evaluated after adoptive transfer in collagen-antibodies- and collagen-induced arthritis models. The in vivo suppressive mechanism on effector T cell proliferation was also investigated. Results : Col-Treg clones are characterized by a cytokine profile (IL10highIL4negIFN-gint) and mediate contact-independent immune suppression. They also share with natural Tregs high expression of GITR, CD39 and Granzyme B. Single infusion of Col-Treg cells reduced incidence and clinical symptoms of arthritis both in preventive and curative settings, with a significant impact on collagen type II antibodies. Importantly, injection of antigen-specific type 1 Treg cells decreases significantly the proliferation of antigen-specific effector T cells in vivo. Conclusion : Our results demonstrate the therapeutic potential of Col-Treg cells in two models of RA, providing evidence that Col-Treg could be an efficient cell-based therapy for RA patients refractory to current treatments.MONTPELLIER-BU Médecine UPM (341722108) / SudocSudocFranceF

Cellular senescence impact on immune cell fate and function

International audienceCellular senescence occurs not only in cultured fibroblasts, but also in undifferentiated and specialized cells from various tissues of all ages, in vitro and in vivo. Here, we review recent findings on the role of cellular senescence in immune cell fate decisions in macrophage polarization, natural killer cell phenotype, and following T-lymphocyte activation. We also introduce the involvement of the onset of cellular senescence in some immune responses including T-helper lymphocyte-dependent tissue homeostatic functions and T-regulatory cell-dependent suppressive mechanisms. Altogether, these data propose that cellular senescence plays a wide-reaching role as a homeostatic orchestrator

Specific overexpression of rheumatoid arthritis-associated HLA-DR alleles and presentation of low-affinity peptides.

International audienceObjective To compare levels of HLA–DR expression in rheumatoid arthritis (RA) patients and healthy controls for whom an ordered expression according to the DR alleles is demonstrated and to test the functional consequences of this expression on peptide presentation. Methods Using monoclonal antibodies that recognize different DRB1 alleles, DR molecules were quantitated at the surface of the peripheral blood B cells of 23 RA patients and 17 healthy subjects. The functional consequences of the level of DR surface expression was tested using a universal model of antigen presentation and mutated peptides with variable affinities for the T cell receptor. Results In healthy subjects, surface HLA–DR molecules were expressed at different levels according to allele (DR53, DR4, and DR11 less than DR1 less than DR7 less than DR15). In RA patients, this hierarchy was not conserved and, furthermore, the density of RA‐associated DR4 and DR1 molecules was enhanced in patients compared with the basal density in healthy individuals. We demonstrated that an increased expression of DR molecules at the surface of antigen‐presenting cells allowed a noteworthy presentation of low‐affinity peptides that under normal conditions are not efficient in generating a T cell response at physiologic surface density of the DR molecules. Conclusion Our results suggest that the specific overexpression of RA‐associated HLA molecules could be responsible for the presentation of low‐affinity autopeptides and therefore the activation of peripheral autoreactive T cells

The control of dendritic cell maturation by pH-sensitive polyion complex micelles.

9International audienceDouble-hydrophilic block copolymer micelles were designed as vectors for ex vivo dendritic cell engineering to improve the delivery of therapeutic molecules in such immune cells. Polymethacrylic acid-b-polyethylene oxide (PMAA2100-b-POE5000)/poly-l-lysine micelles were optimised and showed a hydrodynamic diameter of 30 nm with a peculiar core organised with hydrogen bonds as well as hydrophobic domains. The micelles proved high stability in physiological conditions (pH and ionic strength) and were also able to disassemble under acidic conditions mimicking acidic endolysosomes. The efficient endocytosis of the optimised micelles tested on bone marrow-derived dendritic cells was monitored by fluorescence-activated cell sorting and microscopy analysis. Finally, the micelle biocompatibility permitted a complete control of the dendritic cell-maturation process widening the therapeutical potential of such engineered dendritic cells for cancer vaccines as well as for immunomodulation in autoimmune diseases