Peroxisome Proliferator-activated Receptor-{gamma} Down-regulates Chondrocyte Matrix Metalloproteinase-1 via a Novel Composite Element

Interleukin-1{beta} (IL-1{beta}) induces degradation via hyperexpression of an array of genes, including metalloproteinases (MMP), in cartilage cells during articular degenerative diseases. In contrast, natural ligands for peroxisome proliferator-activated receptors (PPARs) display protective anti-cytokine effects in these cells. We used the PPAR agonist rosiglitazone (Rtz) to investigate PPAR-{gamma} isotype on IL-1{beta}-target genes. Immunocytochemistry, electrophoretic mobility shift, and transient transfection assays revealed a functional PPAR-{gamma} in chondrocytes in vitro. Rtz displayed significant inhibition of IL-1{beta} effects in chondrocytes. Low Rtz concentrations (close to Kd values for PPAR-{gamma}, 0.1 to 1 µM) inhibited the effects of IL-1{beta} on 35S-sulfated proteoglycan production and gelatinolytic activities and downregulated MMP1 expression at mRNA and protein levels. We have investigated the mechanism of action of Rtz against IL-1{beta}-mediated MMP1 gene hyperexpression. Rtz effect occurs at the transcriptional level of the MMP1 promoter, as observed in transiently transfected cells with pMMP1-luciferase vector. Transient expression of wild type PPAR-{gamma} enhanced Rtz inhibitory effect in chondrocytes, whereas a mutated dominant negative PPAR-{gamma} abolished it, supporting the role of PPAR-{gamma} in this effect. MMP1 gene promoter analysis revealed the involvement of a cis-acting element located at -83 to -77, shown to be a composite PPRE/AP1 site. Gel mobility and supershift assays demonstrated that PPAR-{gamma} and c-Fos/c-Jun proteins bind this cis-acting element in a mutually exclusive way. Our data highlight a new PPAR-{gamma}-dependent inhibitory mechanism on IL-1{beta}-mediated cartilage degradation occurring through DNA binding competition on the composite PPRE/AP1 site in the MMP1 promoter

La thérapie cellulaire dans ses applications cliniques

Le cartilage a un médiocre potentiel de réparation spontanée de ses propres lésions. Pour être efficace, le processus de réparation devrait restituer les composants cellulaires et les protéines matricielles du tissu cartilagineux, et surtout reproduire le plus fidèlement possible l’architecture et les propriétés physico-chimiques exceptionnelles de ce tissu pour maintenir sa fonction. La transplantation autologue de greffons de chondrocytes, constitue un réel progrès, dans le cadre restreint de jeunes sportifs, porteurs de lésions du cartilage de petite taille, sans autre atteinte de l’articulation. Des travaux récents montrent que les cellules mésenchymateuses pluripotentes présentes dans la moelle osseuse peuvent aussi être utilisées pour réparer des lésions cartilagineuses expérimentales. L’avantage de cette transplantation est qu’elle pourrait être utilisée pour des lésions étendues du cartilage. Les cellules de moelle sont relativement faciles à prélever, ont un fort pouvoir de prolifération et peuvent se différencier in vitro en cellules chondrogéniques, ostéogéniques ou adipocytaires. Les voies de recherche actuelles sont centrées sur les points suivants : la caractérisation du ou des facteurs susceptibles d’induire spécifiquement l’entrée des cellules pluripotentes dans la voie de différenciation chon- drogénique; la caractérisation des facteurs nutritionnels et environnementaux permettant la survenue du processus de maturation cellulaire des cellules chondrogéniques au sein du greffon; l’élaboration d’un support tri-dimensionnel biocompatible et biodégradable susceptible de recevoir les cellules chondrogéniques, de leur permettre de développer leur processus de maturation et de maintenir autour d’elles les protéines matricielles néoformées; la mise au point d’un biomateriau mixte contenant des cellules chondrogéniques et ostéogéniques réparties sélectivement, devrait permettre d’aborder positivement l’implantation d’un tel greffon dans l’os sous-chondral

Cartilage de croissance dans ses aspects métaboliques et la régulation hormonale de son développement

International audienc

Cartilage Breakdown in Rheumatoid Arthritis

previous Rheumatoid arthritis (RA) is a connective tissue disease characterized by destruction of the joint previous cartilage and subsequently of the underlying bone. previous Cartilagen destruction is due to proteolysis by enzymes called metalloproteinases (MMPs), whose production and expression are regulated by numerous local mediators such as cytokines, growth factors, prostaglandins, oxygen species, and neuropeptides. MMP activation is largely due to a stimulatory effect of cytokines including IL-1β and TNFα. When these cytokines bind to their membrane receptor, they set off signaling cascades, with activation of TGFβ-activating kinase (TAK-1), of NF-κB by Iκ-B kinase, of mitogen-activated protein kinases (MAP kinases), and finally of activator protein-1 (AP-1). Tissue inhibitors of MMPs (TIMPs) specifically inhibit MMPs. The interrelations between joint inflammation and joint destruction remain poorly understood. Experimental data suggest that IL-1 may be involved chiefly in joint destruction and TNF in joint inflammation. However, TNF antagonists are potent inhibitors of joint destruction in clinical practice. These results suggest that the mediators function as a network and that inhibition of a single mediator can affect the entire web. Insights gained into the innermost mechanisms of previous cartilage breakdown in patients with RA have led to major therapeutic breakthroughs. Thus, TNF antagonists have proved highly effective in RA. Future progress will no doubt stem from new knowledge about the extracellular mediators and intracellular signaling pathways that lead to the production and activation of enzymes responsible for previous cartilagenext term degradation

Métabolisme et activité du 25-hydroxycholécalciférol dans les chondrocytes en culture

International audienc

Resveratrol, Potential Therapeutic Interest in Joint Disorders: A Critical Narrative Review

Trans-resveratrol (t-Res) is a natural compound of a family of hydroxystilbenes found in a variety of spermatophyte plants. Because of its effects on lipids and arachidonic acid metabolisms, and its antioxidant activity, t-Res is considered as the major cardioprotective component of red wine, leading to the “French Paradox” health concept. In the past decade, research on the effects of resveratrol on human health has developed considerably in diverse fields such as cancer, neurodegenerative and cardiovascular diseases, and metabolic disorders. In the field of rheumatic disorders, in vitro evidence suggest anti-inflammatory, anti-catabolic, anti-apoptotic and anti-oxidative properties of t-Res in various articular cell types, including chondrocytes and synoviocytes, along with immunomodulation properties on T and B lymphocytes. In preclinical models of osteoarthritis and rheumatoid arthritis, resveratrol has shown joint protective effects, mainly mediated by decreased production of pro-inflammatory and pro-degradative soluble factors, and modulation of cellular and humoral responses. Herein, we comprehensively reviewed evidence supporting a potential therapeutic interest of t-Res in treating symptoms related to rheumatic disorders

La thérapie cellulaire du cartilage : bases cellulaires et moléculaires

L'augmentation de l'espérance de vie rend très urgente la mise au point de techniques de réparation des tissus lésés. Le cartilage articulaire est résistant, élastique et dure toute la vie. Il permet les mouvements des articulations et protége l'os sous-jacent contre les agressions mécaniques et traumatiques. Mais lorsqu'il est lésé, le cartilage ne se répare pas spontanément. Aucun traitement médicamenteux n'étant efficace à ce jour, il paraît licite d'agir précocement sur les lésions traumatiques du cartilage de façon à prévenir l'arthrose et reculer d'autant l'heure de la chirurgie prothétique. La thérapie cellulaire pourrait être une voie de prévention de la survenue de l'arthrose. Le cartilage ne contient qu'un seul type cellulaire, le chondrocyte qui synthétise et sécrète une abondante matrice protéique. Cette dernière assure le maintien des fonctions mécaniques du cartilage. Le concept de thérapie cellulaire consiste à combler la lésion cartilagineuse non seulement avec des chondrocytes sains, mais aussi à reconstituer la structure et les propriétés physico-chimiques de la matrice. La greffe de chondrocytes autologues est à la base de ce concept. Les recherches actuelles portent sur l'utilisation de cellules souches ou progénitrices, associées à un biomatériau "intelligent" permettant le maintien du caractère chondrogénique des cellules, l'introduction du greffon dans la lésion articulaire par des méthodes peu invasives et l'acquisition de propriétés mécaniques proches de celle du cartilage natif

Basic fibroblast growth factor as a selective inducer of matrix Gla protein gene expression in proliferative chondrocytes.

Matrix Gla protein (MGP) is a member of the vitamin K-dependent gamma carboxylase protein family expressed in cartilage. Insulin-like growth factor I (IGF1) stimulates chondrocyte differentiation, whereas basic fibroblast growth factor (FGF2) acts in an opposite manner. We explored the differential expression and regulation by IGF1 and FGF2 of the MGP gene during chondrocyte differentiation. We used a primary culture system of rabbit epiphyseal chondrocytes to show that MGP mRNA is mainly expressed during serum-induced proliferation. Much lower MGP mRNA content is observed in post-mitotic chondrocytes, which newly express alpha 1X procollagen mRNA, a marker of late-differentiated cells. From studies of a series of growth factors, it was shown that IGF1 decreased chondrocyte MGP transcripts, whereas FGF2 had the opposite effect. FGF2 stimulated chondrocyte MGP production in a dose- and time-dependent manner at the mRNA and protein levels. FGF2 acted in a dose- and time-dependent manner, reaching a maximum at 10 ng/ml at 20 h. The protein synthesis inhibitor cycloheximide did not modify FGF2 action, in agreement with a direct effect. Actinomycin D abolished FGF2-induced stimulation, strongly suggesting that FGF2 modulated MGP gene transcription. We transiently transfected chondrocytes with a construct containing the mouse MGP promoter from -5000 to -168 base pairs, relative to the transcription start site of the gene linked to the luciferase gene (MGP-Luc). In transfected cells, FGF2 stimulated luciferase activity up to sevenfold while IGF1 had no effect. Hence, FGF2 induces transcription of the MGP gene via the 5'-flanking region of the gene. Using a series of deleted MGP-Luc constructs, we identified a sequence of 748 base pairs which was sufficient for transcriptional activation by FGF2. These results led us to postulate that the inhibitory chondrogenic action of FGF2 involves a mechanism whereby MGP gene transcription and protein are induced

Endocrine disruptors target collagen type 2 maturation in chondrocytes in vitro – CIME project

Endocrine disruptors target collagen type 2 maturation in chondrocytes in vitro – CIME project. Colloque PNR-PE <National endocrine disruptor research program