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Related Orphan Receptor (relate + orphan_receptor)
Selected AbstractsControl of chondrocyte gene expression by actin dynamics: a novel role of cholesterol/Ror-, signalling in endochondral bone growthJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 9b 2009Anita Woods Abstract Elucidating the signalling pathways that regulate chondrocyte differentiation, such as the actin cytoskeleton and Rho GTPases, during development is essential for understanding of pathological conditions of cartilage, such as chondrodysplasias and osteoarthritis. Manipulation of actin dynamics in tibia organ cultures isolated from E15.5 mice results in pronounced enhancement of endochondral bone growth and specific changes in growth plate architecture. Global changes in gene expression were examined of primary chondrocytes isolated from embryonic tibia, treated with the compounds cytochalasin D, jasplakinolide (actin modifiers) and the ROCK inhibitor Y27632. Cytochalasin D elicited the most pronounced response and induced many features of hypertrophic chondrocyte differentiation. Bioinformatics analyses of microarray data and expression validation by real-time PCR and immunohistochemistry resulted in the identification of the nuclear receptor retinoid related orphan receptor-, (Ror-,) as a novel putative regulator of chondrocyte hypertrophy. Expression of Ror-, target genes, (Lpl, fatty acid binding protein 4 [Fabp4], Cd36 and kruppel-like factor 5 [Klf15]) were induced during chondrocyte hypertrophy and by cytochalasin D and are cholesterol dependent. Stimulation of Ror-, by cholesterol results in increased bone growth and enlarged, rounded cells, a phenotype similar to chondrocyte hypertrophy and to the changes induced by cytochalasin D, while inhibition of cholesterol synthesis by lovastatin inhibits cytochalasin D induced bone growth. Additionally, we show that in a mouse model of cartilage specific (Col2-Cre) Rac1, inactivation results in increased Hif-1, (a regulator of Rora gene expression) and Ror-,+ cells within hypertrophic growth plates. We provide evidence that cholesterol signalling through increased Ror-, expression stimulates chondrocyte hypertrophy and partially mediates responses of cartilage to actin dynamics. [source] Role of osteopontin in synovial Th17 differentiation in rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 10 2010Guangjie Chen Objective Osteopontin (OPN) that is aberrantly produced in rheumatoid synovium is thought to play an important role in rheumatoid arthritis (RA). This study was undertaken to investigate the role of OPN in the differentiation and accumulation of Th17 cells in rheumatoid synovium. Methods Peripheral blood mononuclear cells and purified CD4+ T cells derived from patients with RA or healthy controls were used to test the effect of OPN in vitro. Cytokine expression was determined by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. Intracellular staining and flow cytometry were used to detect the percentages of Th17 cells and OPN receptors. Signaling and molecular events were analyzed by immunoblotting and chromatin immunoprecipitation. Results The levels of OPN correlated significantly with interleukin-17 (IL-17) production and the frequency of Th17 cells in the synovial fluid (SF) of RA patients. Endogenous OPN produced in RA SF was responsible for markedly increased production of IL-17 in T cells, which was blocked by OPN antibody. The effect of OPN in Th17 differentiation was mediated through a mechanism independent of the IL-6/STAT-3 pathway or other cytokines and specifically involved the OPN receptors CD44 and CD29 and the transcription factor retinoic acid,related orphan receptor (ROR). Furthermore, OPN was found to induce H3 acetylation of the IL17A gene promoter, mainly through the CD44 binding domain in CD4+ T cells, allowing the interaction of the IL17A gene locus with ROR. Conclusion This study reveals new evidence of the critical role of OPN in Th17 differentiation in rheumatoid synovitis. [source] Interleukin-23 promotes Th17 differentiation by inhibiting T-bet and FoxP3 and is required for elevation of interleukin-22, but not interleukin-21, in autoimmune experimental arthritisARTHRITIS & RHEUMATISM, Issue 4 2010Adriana M. C. Mus Objective To examine the role of interleukin-23 (IL-23) in subgroup polarization of IL-17A,positive and/or interferon-, (IFN,),positive T cells in autoimmune disease,prone DBA/1 mice with and without collagen-induced arthritis. Methods A magnetic-activated cell sorting system was used to isolate CD4+ T cells from the spleen of naive and type II collagen (CII),immunized DBA/1 mice. These CD4+ T cells were stimulated in vitro under Th0, Th1, or different Th17 culture conditions. Intracellular staining for IL-17A and IFN, was evaluated by flow cytometry. In addition, Th17 cytokines and T helper,specific transcription factors were analyzed by enzyme-linked immunosorbent assay and/or quantitative polymerase chain reaction. Results In CD4+ T cells from naive DBA/1 mice, IL-23 alone hardly induced retinoic acid,related orphan receptor ,t (ROR,t), Th17 polarization, and Th17 cytokines, but it inhibited T-bet expression. In contrast, transforming growth factor ,1 (TGF,1)/IL-6 was a potent inducer of ROR,t, ROR,, IL-17A, IL-17F, IL-21, and FoxP3 in these cells. In contrast to TGF,1/IL-6, IL-23 was critical for the induction of IL-22 in CD4+ T cells from both naive and CII-immunized DBA/1 mice. Consistent with these findings, IL-23 showed a more pronounced induction of the IL-17A+IFN,, subset in CD4+ T cells from CII-immunized mice. However, in CD4+ T cells from naive mice, IL-23 significantly increased the TGF,1/IL-6,induced Th17 polarization, including elevated levels of IL-17A and IL-17F and decreased expression of T-bet and FoxP3. Of note, the IL-23,induced increase in IL-17A and IL-17F levels was prevented in T-bet,deficient mice. Conclusion IL-23 promotes Th17 differentiation by inhibiting T-bet and FoxP3 and is required for elevation of IL-22, but not IL-21, levels in autoimmune arthritis. These data indicate different mechanisms for IL-23 and TGF,1/IL-6 at the transcription factor level during Th17 differentiation in autoimmune experimental arthritis. [source] Inhibition of synovial hyperplasia, rheumatoid T cell activation, and experimental arthritis in mice by sulforaphane, a naturally occurring isothiocyanateARTHRITIS & RHEUMATISM, Issue 1 2010Jin-Sun Kong Objective To investigate whether sulforaphane (SFN), an isothiocyanate derived from cruciferous vegetables such as broccoli, regulates synoviocyte hyperplasia and T cell activation in rheumatoid arthritis (RA). Methods Synoviocyte survival was assessed by MTT assay. The levels of Bcl-2, Bax, p53, and pAkt were determined by Western blot analysis. Cytokine concentrations in culture supernatants from mononuclear cells were analyzed by enzyme-linked immunosorbent assay. The in vivo effects of SFN were examined in mice with experimentally induced arthritis. Results SFN induced synoviocyte apoptosis by modulating the expression of Bcl-2/Bax, p53, and pAkt. In addition, nonapoptotic doses of SFN inhibited T cell proliferation and the production of interleukin-17 (IL-17) and tumor necrosis factor , (TNF,) by RA CD4+ T cells stimulated with anti-CD3 antibody. Anti-CD3 antibody,induced increases in the expression of retinoic acid,related orphan receptor ,t and T-bet were also repressed by SFN. Moreover, the intraperitoneal administration of SFN to mice suppressed the clinical severity of arthritis induced by injection of type II collagen (CII), the anti-CII antibody levels, and the T cell responses to CII. The production of IL-17, TNF,, IL-6, and interferon-, by lymph node cells and spleen cells from these mice was markedly reduced by treatment with SFN. Anti-CII antibody,induced arthritis in mice was also alleviated by SFN injection. Conclusion SFN was found to inhibit synovial hyperplasia, activated T cell proliferation, and the production of IL-17 and TNF, by rheumatoid T cells in vitro. The antiarthritic and immune regulatory effects of SFN, which were confirmed in vivo, suggest that SFN may offer a possible treatment option for RA. [source] GATA-3 protects against severe joint inflammation and bone erosion and reduces differentiation of Th17 cells during experimental arthritisARTHRITIS & RHEUMATISM, Issue 3 2009Jan Piet van Hamburg Objective Rheumatoid arthritis is associated with the infiltration of T helper cells into the joints. It is unclear whether interferon-, (IFN,),producing Th1 cells or the novel T helper subset, interleukin-17 (IL-17),producing Th17 cells, are the pathogenic mediators of joint inflammation in chronic nonautoimmune arthritis. Therefore, this study was aimed at examining whether the Th2-specific transcription factor GATA-3 can regulate arthritis, in an experimental murine model, by modulating Th1 and/or Th17 cell polarization. Methods Arthritis was induced with methylated bovine serum albumin (mBSA) in both wild-type and CD2 T cell,specific GATA-3 (CD2,GATA-3),transgenic mice. At days 1 and 7 after the induction of arthritis, knee joints were scored macroscopically for arthritis severity and for histologic changes. Single-cell suspensions were generated from the spleens, lymph nodes, and inflamed knee joints. Cytokine expression by CD4+ T cells was determined using flow cytometry, and IL-17 expression in the inflamed knee joints was determined by enzyme-linked immunosorbent assay. Analyses of gene expression were performed for Th17-associated factors. Results Wild-type mice developed severe joint inflammation, including massive inflammatory cell infiltration and bone erosion that increased significantly over time, reaching maximal arthritis scores at day 7. In contrast, only mild joint inflammation was observed in CD2,GATA-3,transgenic mice. This mild effect was further accompanied by systemic and local reductions in the numbers of IL-17+IFN,, and IL-17+IFN,+, but not IL-17,IFN,+, CD4+ T cells, and by induction of Th2 cytokine expression. Moreover, GATA-3 overexpression resulted in reduced gene expression of the Th17-associated transcription factor retinoic acid,related orphan receptor ,t. Conclusion These results indicate that enforced GATA-3 expression protects against severe joint inflammation and bone erosion in mice, accompanied by reduced differentiation of Th17 cells, but not Th1 cells, during mBSA-induced arthritis. [source] | ||||||||||