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Rheumatoid Synovium (rheumatoid + synovium)
Selected AbstractsThe X-box binding protein-1 transcription factor is required for plasma cell differentiation and the unfolded protein responseIMMUNOLOGICAL REVIEWS, Issue 1 2003Neal N. Iwakoshi Summary:, X-box binding protein-1 (XBP-1) is a transcription factor essential for plasma cell differentiation. XBP-1 transcripts are found at high levels in plasma cells from rheumatoid synovium and myeloma cell lines. Lymphoid chimeras deficient in XBP-1 have a profound defect in plasma cell differentiation, with few plasma cells in their periphery and severely reduced serum immunoglobulin levels. When introduced into B-lineage cells, XBP-1 initiates plasma cell differentiation. XBP-1 is also the mammalian homologue of the yeast transcription factor Hac1p, an important component of the unfolded protein response (UPR). The UPR allows cells to tolerate conditions of endoplasmic reticulum (ER) stress caused by misfolded proteins. Studies examining the relationship between plasma cell differentiation, XBP-1, and the UPR demonstrate that this novel signaling system is vital for plasma cell differentiation. Signals that induce plasma cell differentiation and the UPR cooperate via XBP-1 to induce terminal B-cell differentiation. Additionally, XBP-1 plays an important role in the regulation of interleukin-6 production, a cytokine essential for plasma cell survival. [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] The programmed death 1/programmed death ligand 1 inhibitory pathway is up-regulated in rheumatoid synovium and regulates peripheral T cell responses in human and murine arthritisARTHRITIS & RHEUMATISM, Issue 7 2010Amalia P. Raptopoulou Objective T cells play a major role in the pathogenesis of rheumatoid arthritis (RA). The programmed death 1 (PD-1)/programmed death ligand 1 (PDL-1) pathway is involved in peripheral tolerance through inhibition of T cells at the level of synovial tissue. The aim of this study was to examine the role of PD-1/PDL-1 in the regulation of human and murine RA. Methods In synovial tissue and synovial fluid (SF) mononuclear cells from patients with RA, expression of PD-1/PDL-1 was examined by immunohistochemistry and flow cytometry, while PD-1 function was assessed in RA peripheral blood (PB) T cells after stimulation of the cells with anti-CD3 and PDL-1.Fc to crosslink PD-1. Collagen-induced arthritis (CIA) was induced in PD-1,/, C57BL/6 mice, and recombinant PDL-1.Fc was injected intraperitoneally to activate PD-1 in vivo. Results RA synovium and RA SF were enriched with PD-1+ T cells (mean ± SEM 24 ± 5% versus 4 ± 1% in osteoarthritis samples; P = 0.003) and enriched with PDL-1+ monocyte/macrophages. PD-1 crosslinking inhibited both T cell proliferation and production of interferon-, (IFN,) in RA patients; PB T cells incubated with RA SF, as well as SF T cells from patients with active RA, exhibited reduced PD-1,mediated inhibition of T cell proliferation at suboptimal, but not optimal, concentrations of PDL-1.Fc. PD-1,/, mice demonstrated increased incidence of CIA (73% versus 36% in wild-type mice; P < 0.05) and greater severity of CIA (mean maximum arthritis score 5.0 versus 2.3 in wild-type mice; P = 0.040), and this was associated with enhanced T cell proliferation and increased production of cytokines (IFN, and interleukin-17) in response to type II collagen. PDL-1.Fc treatment ameliorated the severity of CIA and reduced T cell responses. Conclusion The negative costimulatory PD-1/PDL-1 pathway regulates peripheral T cell responses in both human and murine RA. PD-1/PDL-1 in rheumatoid synovium may represent an additional target for immunomodulatory therapy in RA. [source] Amelioration of experimental arthritis by a telomerase-dependent conditionally replicating adenovirus that targets synovial fibroblastsARTHRITIS & RHEUMATISM, Issue 11 2009Shih-Yao Chen Objective Synovial fibroblasts (SFs) play a pivotal role in the pathogenesis of rheumatoid arthritis (RA). It has been documented that the phenotype of rheumatoid synovium is similar, in many respects, to that of an aggressive tumor. In this study, a novel, genetically engineered adenovirus was designed to lyse SFs that exhibit high telomerase activity and p53 mutations, and its effects as a novel therapeutic strategy were assessed in an experimental arthritis model. Methods An E1B,55-kd,deleted adenovirus driven by the human telomerase reverse transcriptase promoter was constructed (designated Ad.GS1). Cytolysis of SFs and productive replication of Ad.GS1 in the SFs of rats with collagen-induced arthritis (CIA), as well as the SFs of patients with RA (RASFs), were assessed in vitro and in vivo. Treatment responses, as well as the presence of disease-related cytokines and enzymes in the ankle joints, were determined in the murine model. Results Ad.GS1 replicated in and induced cytolysis of human RASFs and SFs from arthritic rats, but spared normal fibroblasts. Bioluminescence imaging in vivo also demonstrated replication of Ad.GS1 in arthritic rat joints, but not in normal rat joints. Intraarticular administration of Ad.GS1 significantly reduced the ankle circumference, articular index scores, radiographic scores, and histologic scores and decreased the production of interleukin-1,, matrix metalloproteinase 9, and prolyl 4-hydroxylase in rats with CIA compared with their control counterparts. Conclusion This study is the first to demonstrate the amelioration of arthritic symptoms by a novel, telomerase-dependent adenovirus in the rat CIA model, an experimental model that resembles human RA. In addition, the results suggest that because of its ability to induce cytolysis of SFs, this virus may be further explored as a therapeutic agent in patients with RA. [source] Galectin 3 induces a distinctive pattern of cytokine and chemokine production in rheumatoid synovial fibroblasts via selective signaling pathwaysARTHRITIS & RHEUMATISM, Issue 6 2009Andrew Filer Objective High expression of galectin 3 at sites of joint destruction in rheumatoid arthritis (RA) suggests that galectin 3 plays a role in RA pathogenesis. Previous studies have demonstrated the effects of galectins on immune cells, such as lymphocytes and macrophages. This study was undertaken to investigate the hypothesis that galectin 3 induces proinflammatory effects in RA by modulating the pattern of cytokine and chemokine production in synovial fibroblasts. Methods Matched samples of RA synovial and skin fibroblasts were pretreated with galectin 3 or tumor necrosis factor , (TNF,), and the levels of a panel of cytokines, chemokines, and matrix metalloproteinases (MMPs) were determined using enzyme-linked immunosorbent assays and multiplex assays. Specific inhibitors were used to dissect signaling pathways, which were confirmed by Western blotting and NF-,B activation assay. Results Galectin 3 induced secretion of interleukin-6 (IL-6), granulocyte,macrophage colony-stimulating factor, CXCL8, and MMP-3 in both synovial and skin fibroblasts. By contrast, galectin 3,induced secretion of TNF,, CCL2, CCL3, and CCL5 was significantly greater in synovial fibroblasts than in skin fibroblasts. TNF, blockade ruled out autocrine TNF,-stimulated induction of chemokines. The MAPKs p38, JNK, and ERK were necessary for IL-6 production, but phosphatidylinositol 3-kinase (PI 3-kinase) was required for selective CCL5 induction. NF-,B activation was required for production of both IL-6 and CCL5. Conclusion Our findings indicate that galectin 3 promotes proinflammatory cytokine secretion by tissue fibroblasts. However, galectin 3 induces the production of mononuclear cell,recruiting chemokines uniquely from synovial fibroblasts, but not matched skin fibroblasts, via a PI 3-kinase signaling pathway. These data provide further evidence of the role of synovial fibroblasts in regulating the pattern and persistence of the inflammatory infiltrate in RA and suggest a new and important functional consequence of the observed high expression of galectin 3 in the rheumatoid synovium. [source] Development of an ex vivo cellular model of rheumatoid arthritis: Critical role of cd14-positive monocyte/macrophages in the development of pannus tissueARTHRITIS & RHEUMATISM, Issue 9 2007Toshiko Nozaki Objective To establish an ex vivo cellular model of pannus, the aberrant overgrowth of human synovial tissue (ST). Methods Inflammatory cells that infiltrated pannus tissue from patients with rheumatoid arthritis (RA) were collected without enzyme digestion, and designated as ST-derived inflammatory cells. Single-cell suspensions of ST-derived inflammatory cells were cultured in medium alone. Levels of cytokines produced in culture supernatants were measured using enzyme-linked immunosorbent assay kits. ST-derived inflammatory cells were transferred into the joints of immunodeficient mice to explore whether these cells could develop pannus. CD14 and CD2 cells were depleted by negative selection. Results Culture of ST-derived inflammatory cells from 92 of 111 patients with RA resulted in spontaneous reconstruction of inflammatory tissue in vitro within 4 weeks. Ex vivo tissue contained fibroblasts, macrophages, T cells, and tartrate-resistant acid phosphatase,positive multinucleated cells. On calcium phosphate,coated slides, ST-derived inflammatory cell cultures showed numerous resorption pits. ST-derived inflammatory cell cultures continuously produced matrix metalloproteinase 9 and proinflammatory cytokines associated with osteoclastogenesis, such as tumor necrosis factor ,, interleukin-8, and macrophage colony-stimulating factor. More importantly, transferring ST-derived inflammatory cells into the joints of immunodeficient mice resulted in the development of pannus tissue and erosive joint lesions. Both in vitro development and in vivo development of pannus tissue by ST-derived inflammatory cells were inhibited by depleting CD14-positive, but not CD2-positive, cells from ST-derived inflammatory cells. Conclusion These findings suggest that overgrowth of inflammatory cells from human rheumatoid synovium simulates the development of pannus. This may prove informative in the screening of potential antirheumatic drugs. [source] Light up-regulated on B lymphocytes and monocytes in rheumatoid arthritis mediates cellular adhesion and metalloproteinase production by synoviocytesARTHRITIS & RHEUMATISM, Issue 4 2007Young Mo Kang Objective To study the expression of LIGHT (tumor necrosis factor superfamily 14) and herpesvirus entry mediator (HVEM; tumor necrosis factor receptor superfamily 14) in rheumatoid arthritis (RA) and to determine the regulatory role of LIGHT on the effector functions of fibroblast-like synoviocytes (FLS). Methods The expression of LIGHT and HVEM was assessed by immunohistochemical staining of synovial tissue and by flow cytometric analysis of mononuclear cells. The presence of HVEM and lymphotoxin , receptor was measured by reverse transcriptase,polymerase chain reaction and by flow cytometry. The regulation of effector molecules, including matrix metalloproteinases (MMPs) and adhesion molecules, was evaluated. The adhesiveness of FLS was determined by adhesion assay. Results HVEM was detected in most cell types within rheumatoid synovial tissue, while only a few cells were positive for LIGHT. In RA patients, LIGHT expression was significantly up-regulated only in CD20+ B cells and monocytes, whereas the mean fluorescence intensity of HVEM was down-regulated in mononuclear cells. The stimulation of FLS with LIGHT resulted in the production of MMPs and the expression of adhesion molecules, which were efficiently inhibited by dexamethasone. LIGHT-mediated up-regulation of MMPs and intercellular adhesion molecule 1 was blocked by inhibitors of NF-,B and JNK, whereas up-regulation of vascular cell adhesion molecule 1 was blocked by inhibitors of phosphatidylinositol 3-kinase, as well as NF-,B. Conclusion These data suggest that binding of LIGHT with its receptors may play a role in the progression of inflammation within rheumatoid synovium, especially by mediating the interactions between infiltrating inflammatory cells and stromal cells. These findings thus emphasize the relevance of LIGHT as a potential therapeutic target in RA. [source] Sphingosine 1-phosphate/sphingosine 1-phosphate receptor 1 signaling in rheumatoid synovium: Regulation of synovial proliferation and inflammatory gene expressionARTHRITIS & RHEUMATISM, Issue 3 2006Masayasu Kitano Objective Sphingosine 1-phosphate (S1P) is involved in various pathologic conditions and has been implicated as an important mediator of angiogenesis, inflammation, cancer, and autoimmunity. This study was undertaken to examine the role of S1P/S1P1 signaling in the pathogenesis of rheumatoid arthritis (RA). Methods We examined S1P1 messenger RNA (mRNA) and protein levels in RA synoviocytes and MH7A cells by reverse transcriptase,polymerase chain reaction and Western blotting. We also performed S1P1 immunohistochemistry analysis in synovial tissue from 28 RA patients and 18 osteoarthritis (OA) patients. We investigated the effects of S1P on proliferation by WST-1 assay, and its effects on tumor necrosis factor , (TNF,), or interleukin-1, (IL-1,),induced cyclooxygenase 2 (COX-2) expression and prostaglandin E2 (PGE2) production in RA synoviocytes and MH7A cells by Western blotting and enzyme-linked immunosorbent assay, respectively. Finally, we examined whether these effects of S1P were sensitive to pertussis toxin (PTX), an inhibitor of the Gi/Go proteins. Results S1P1 mRNA and protein were detected in RA synoviocytes and MH7A cells. S1P1 was more strongly expressed in synovial lining cells, vascular endothelial cells, and inflammatory mononuclear cells of RA synovium compared with OA synovium. S1P increased the proliferation of RA synoviocytes and MH7A cells. S1P alone significantly enhanced COX-2 expression and PGE2 production. Moreover, S1P enhanced expression of COX-2 and production of PGE2 induced by stimulation with TNF, or IL-1, in RA synoviocytes and MH7A cells. These effects of S1P were inhibited by pretreatment with PTX. Conclusion These findings suggest that S1P signaling via S1P receptors plays an important role in cell proliferation and inflammatory cytokine,induced COX-2 expression and PGE2 production by RA synoviocytes. Thus, regulation of S1P/S1P1 signaling may represent a novel therapeutic target in RA. [source] Analysis of the function, expression, and subcellular distribution of human tristetraprolinARTHRITIS & RHEUMATISM, Issue 5 2002Seth A. Brooks Objective The zinc-finger protein tristetraprolin (TTP) has been demonstrated to regulate tumor necrosis factor , (TNF,) messenger RNA (mRNA) instability in murine macrophages. We sought to develop a model system to characterize the effects of human TTP (hTTP) on TNF, 3,-untranslated region (3,-UTR)-mediated expression. We also generated a specific polyclonal antibody against hTTP that enabled the examination of the subcellular distribution of hTTP and its RNA binding in vivo. Methods Transfection of reporter gene constructs were used to functionally characterize the role of hTTP in regulating TNF, expression in a 3,-UTR-dependent manner. An immunoprecipitation reverse transcription-polymerase chain reaction technique, immunoblotting, immunocytochemistry, and sucrose density fractionation were used to identify and localize hTTP. Results We found that hTTP interacted with human TNF, mRNA in the cytoplasm. The presence of the TNF, 3,-UTR was sufficient to confer binding by TTP in vivo. This interaction resulted in reduced luciferase reporter gene activity in a TNF, 3,-UTR adenine-uridine-rich element (ARE)-dependent manner. Immunoblotting and immunocytochemistry indicated that endogenous and transfected hTTP localized to the cytoplasm. Results of sucrose density fractionation studies were consistent with a polysomal location of hTTP. In rheumatoid synovium, hTTP expression was restricted to cells in the synovial lining layers. Conclusion Through the development of an antiserum specific for hTTP, we have been able to demonstrate that hTTP binds specifically to the TNF, 3,-UTR and reduces reporter gene expression in an ARE-specific manner. These studies establish that hTTP is likely to function in a similar, if not identical manner, in the posttranscriptional regulation of TNF,. Understanding the posttranscriptional regulation of TNF, biosynthesis is important for the development of novel treatment strategies in rheumatoid arthritis. [source] Expression of membrane-type 1 matrix metalloproteinase in rheumatoid synovial cellsCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2001S. Honda Membrane-type 1 matrix metalloproteinase (MT1-MMP) is thought to be a putative regulator of pro-gelatinase A (MMP-2) in the rheumatoid synovium. In this study, we examined the effects of IL-1,, one of the inflammatory cytokines, on the expression of MT1-MMP and the activation of pro-MMP-2 using rheumatoid synovial cells. We also studied the effects of KE-298 (2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid), a new disease-modifying anti-rheumatic drug (DMARD), on MT1-MMP expression of rheumatoid synovial cells. Type B synovial cells (fibroblast-like synovial cells) were cultured with KE-298 (25,100 µg/ml) in the presence of IL-1, for 48 h. Activation of pro-MMP-2 secreted from synovial cells was analysed by gelatin zymography. Reverse transcription,polymerase chain reaction (RT,PCR) methods were used to detect MT1-MMP mRNA. MT1-MMP protein expression on synovial cells was examined by anti-MT1-MMP immunoblot. An active form of MMP-2 was demonstrated in the culture media conditioned by IL-1,-stimulated synovial cells. In addition, MT1-MMP mRNA and protein expression of rheumatoid synovial cells were increased by IL-1, treatment. KE-298 blocked this IL-1,-induced pro-MMP-2 activation and MT1-MMP expression, but did not affect IL-1,-induced tissue inhibitor of metalloproteinase-2 (TIMP-2) secretion from rheumatoid synovial cells. These findings indicate that activation of rheumatoid synovial cells by IL-1, results in the induction of MT1-MMP expression. Given that MT1-MMP promotes matrix degradation by activating pro-MMP-2, these results suggest a novel mechanism whereby cytokine may contribute to articular destruction in rheumatoid arthritis (RA). KE-298 may prevent this process by down-regulating MT1-MMP expression. [source] | ||||||||||