Cartilage destruction mediated by synovial fibroblasts does not depend on proliferation in rheumatoid arthritis

The aim of the study was to investigate the relationship between invasion and proliferation in rheumatoid arthritis synovial fibroblasts (RASFs). In vitro, RASFs, normal synovial fibroblasts (NSFs), and RASFs transformed with SV40 T-antigen (RASF(SV40)) were analyzed for the expression of cell surface markers (Thy1, VCAM-1, ICAM-1, CD40, CD44) and their proliferation by flow cytometry. Furthermore, colony-forming unit assays were performed and the expression of matrix metalloproteinases (MMP)-14 and cathepsin K mRNA were determined by real-time polymerase chain reaction. In vivo, in the severe combined immunodeficiency (SCID) mouse co-implantation model, RASFs, NSFs, and RASF(SV40) were tested for cartilage invasion, cellular density, and for their expression of the cell cycle-associated protein Ki67. In the SCID mouse co-implantation model, RASFs invaded significantly stronger into the cartilage than NSFs and RASF(SV40). Of note, RASF(SV40) cells formed tumor-like tissues, and the cellular density adjacent to the cartilage was significantly higher than in RASFs or NSFs. In turn, the proliferation marker Ki67 was strongly expressed in the SV40-transformed synoviocytes in SCID mice, but not in RASFs, and specifically not at sites of cartilage invasion. Using the colony-forming unit assay, RASFs and NSFs did not form colonies, whereas RASF(SV40) lost contact inhibition. In vitro, the proliferative rate of RASFs was low (4.3% S phase) in contrast to RASF(SV40) (24.4%). Expression of VCAM-1 was significantly higher, whereas of ICAM-1 was significantly lower, in RASFs than in RASF(SV40). CD40 was significantly stronger expressed in RASF(SV40), whereas CD44 and AS02 were present at the same degree in almost all synoviocytes. Expression of cathepsin K and matrix metalloproteinase-14 mRNA was significantly higher in RASFs than in the RASF(SV40). Our data demonstrate clearly that invasion of cartilage is mediated by activated RASFs characterized by increased expression of adhesion molecules, matrix-degrading enzymes, but does not depend on cellular proliferation, suggesting the dissociation of invasion and proliferation in RASFs.     

钩吻碱通过下调circ_001680抑制类风湿关节炎滑膜成纤维细胞增殖和侵袭

目的探讨钩吻碱对类风湿关节炎滑膜成纤维细胞(RASFs)增殖、迁移和侵袭的影响及可能机制。方法体外分离培养RASFs。经50、100、200μg/mL的钩吻碱干预24 h或转染circ_001680的小干扰RNA或过表达载体至RASFs后,CCK-8法和克隆形成实验检测细胞增殖;划痕实验检测细胞迁移;Transwell小室法检测细胞侵袭;蛋白印迹法检测E-cadherin和N-cadherin蛋白表达;RT-qPCR检测circ_001680表达。结果钩吻碱或干扰circ_001680表达可降低RASFs的增殖、克隆形成数、划痕愈合率和侵袭细胞数及细胞中N-cadherin蛋白表达(P<0.05),而促进E-cadherin蛋白表达(P<0.05)。钩吻碱可降低RASFs中circ_001680的表达(P<0.05),过表达circ_001680减轻钩吻碱对RASFs增殖、迁移和侵袭的抑制作用。结论钩吻碱可抑制RASFs增殖、迁移和侵袭,其作用机制可能与下调circ_001680表达有关。     

Estrogen inhibits apoptosis and promotes CC motif chemokine ligand 13 expression on synovial fibroblasts in rheumatoid arthritis

Objective: Female patients have a higher prevalence of rheumatoid arthritis (RA) than male patients, suggesting that female sex hormones contribute to the disease pathogenesis. We herein report the findings of our study, which was conducted to clarify the role of estrogen in the pathogenesis of RA.

Methods: Cultured human synovial fibroblasts from a patient with RA were treated with 17β-estradiol (E₂). The effects of E₂ against cellular activation and apoptosis were evaluated. To identify the disease-related genes altered by E₂ treatment, the changes in the gene expression of the cells stimulated with and without E₂ were evaluated using a microarray analysis.

Results: We found that E₂-mediated cellular activation signaling through extracellular signal-regulated kinase (ERK)-1/2. E₂ possessed a suppressive effect for apoptosis and a promotive effect for tumor necrosis factor (TNF)-α-induced matrix metalloproteinase (MMP)-3 production on the synovial fibroblasts. A microarray analysis revealed that E₂ profoundly upregulated CC motif chemokine ligand 13 (CCL13) gene expression.

Conclusions: E₂ could mediate cellular activation signaling through ERK-1/2 on the synovial fibroblasts. The present data suggest that E₂ has adverse effects on the pathogenesis of RA as a result of unregulated cell death, increased TNF-α-induced MMP-3 production, and CCL13 overproduction, subsequently resulting in the disease progression of RA.     

Estrogen inhibits apoptosis and promotes CC motif chemokine ligand 13 expression on synovial fibroblasts in rheumatoid arthritis

Objective: Female patients have a higher prevalence of rheumatoid arthritis (RA) than male patients, suggesting that female sex hormones contribute to the disease pathogenesis. We herein report the findings of our study, which was conducted to clarify the role of estrogen in the pathogenesis of RA. Methods: Cultured human synovial fibroblasts from a patient with RA were treated with 17β-estradiol (E(2)). The effects of E(2) against cellular activation and apoptosis were evaluated. To identify the disease-related genes altered by E(2) treatment, the changes in the gene expression of the cells stimulated with and without E(2) were evaluated using a microarray analysis. Results: We found that E(2)-mediated cellular activation signaling through extracellular signal-regulated kinase (ERK)-1/2. E(2) possessed a suppressive effect for apoptosis and a promotive effect for tumor necrosis factor (TNF)-α-induced matrix metalloproteinase (MMP)-3 production on the synovial fibroblasts. A microarray analysis revealed that E(2) profoundly upregulated CC motif chemokine ligand 13 (CCL13) gene expression. Conclusions: E(2) could mediate cellular activation signaling through ERK-1/2 on the synovial fibroblasts. The present data suggest that E(2) has adverse effects on the pathogenesis of RA as a result of unregulated cell death, increased TNF-α-induced MMP-3 production, and CCL13 overproduction, subsequently resulting in the disease progression of RA.     

JAB1 determines the response of rheumatoid arthritis synovial fibroblasts to tumor necrosis factor-alpha

Fibroblast-like synoviocytes (FLSs) of patients with rheumatoid arthritis (RA FLSs) exhibit prosurvival, rather than apoptotic, response to tumor necrosis factor (TNF)-alpha stimulation. Here, we show that JAB1 is a critical regulator of the TNF-alpha-mediated anti-apo-ptosis pathways in RA FLSs. We found that knockdown of JAB1 using small interfering (si)RNA led to restoration of the TNF-alpha-induced apoptosis response, reduction of nuclear factor-kappaB activity, delayed degradation of IkappaB-alpha, and inhibited phosphorylation of JNK. Analysis of the interactions of JAB1 by reciprocal co-immunoprecipitations and confocal microscopy revealed that JAB1 interacts with TNF receptor-associated-factor 2 (TRAF2). The generation of the anti-apoptotic signal on binding of TNF-alpha to the TNF receptor (TNFR)1 has been shown to be associated with the recruitment of TRAF2 to the TNFR1 in a process that requires ubiquitination of TRAF2 with lysine-63-linked polyubiquitin chains. We found that TNF-alpha stimulation of JAB1 siRNA-transfected RA FLSs failed to stimulate ubiquitination of TRAF2. Thus, we conclude that JAB1-regulated ubiquitination of TRAF2 is a novel mechanism whereby TNF-alpha can induce anti-apoptosis signaling and production of matrix metalloproteinases through activation of nuclear factor-kappaB and JNK in RA FLSs.     

Circulating levels of TNF-like cytokine 1A (TL1A) and its decoy receptor 3 (DcR3) in rheumatoid arthritis

TL1A is a novel TNF-like cytokine, which provides co-stimulatory and Th1-polarizing signals to activated lymphocytes, via binding to death-domain receptor 3 (DR3). These functions are inhibited when TL1A associates to decoy receptor 3 (DcR3). We investigated the serum expression of TL1A and DcR3 in 81 patients with RA and 51 healthy controls. TL1A concentrations were elevated in patients by 5-fold (P<0.00001). This increase was more prominent in RFactor-positive patients and correlated with clinical activity in this subgroup. DcR3 was detected more frequently and in significantly higher values in RA-derived sera, correlated strongly with TL1A, and was present in inflammatory synovial fluid. Severe RA stage was associated with highly elevated TL1A and DcR3 serum levels. Treatment with an anti-TNF agent significantly decreased TL1A serum levels. We conclude that TL1A may serve as an inflammatory marker in RA. Interactions between TL1A and its receptors may be important in the pathogenesis of RA.     

MicroRNA-16对类风湿关节炎患者滑膜成纤维细胞增殖、侵袭及细胞因子分泌的影响

 目的:研究microRNA-16（miR-16）对类风湿关节炎（rheumatoid arthritis,RA）患者滑膜成纤维细胞（rheumatoid arthritis synovial fibroblasts,RASFs）增殖、侵袭及细胞因子分泌的影响。方法: 体外分离培养RASFs,脂质体转染化学合成的miR-16 mimic或miR-16抑制剂,分别采用MTT法、Transwell小室法和流式细胞术检测其对RASFs增殖、侵袭及凋亡的影响;RT-PCR和Western blotting检测miR-16对RASFs基质金属蛋白酶3/13（matrix metalloproteinase 3/13,MMP3/13）及白细胞介素1β（interleukin 1β,IL-1β）表达的影响。结果:增殖实验结果表明miR-16可显著抑制RASFs的增殖;细胞侵袭结果表明miR-16可显著抑制RASFs的侵袭;流式细胞术检测发现miR-16对RASFs凋亡无显著影响;miR-16可下调MMP3/13及IL-1β的表达水平。结论:  miR-16在RA的发生中起着重要作用,它可能通过下调MMP3/13及IL-1β的表达抑制RASFs增殖和侵袭。这为进一步研究miR-16在RA中的作用机制奠定了基础。     

Comparative proliferation of non-rheumatoid and rheumatoid human synovial cells

While normal synovial membrane cells have a very long doubling time, rheumatoid arthritis increases cell turn-over leading to the formation of a pannus. We studied the comparative proliferative behaviour in culture of synoviocytes of rheumatoid (RA) and non-rheumatoid (NR) origin in order to evaluate the usefulness of this model to investigate the drugs used in the treatment of inflammatory diseases. First-passage cultures of cells from patients with clinically defined non-inflammatory joint disease or rheumatoid arthritis were observed for 8 days. In the presence of various combinations of supplemented media, 3H-thymidine incorporation, protein content and cell density were assessed. In addition to a relationship between the fetal calf serum (FCS) concentration and cell growth, it was found that RA cells proliferated more rapidly than NR cells. In 1% FCS, protein content and cell density increased in RA cultures whereas NR synoviocytes accumulated in the quiescent phase. In 5% and 10% FCS, RA cells responded more strongly than NR in terms of protein and DNA synthesis and cell division. After 48 hours of relative FCS deprivation, NR cells abruptly started to proliferate; the response of RA cultures was delayed, but the synoviocytes quickly reached preconfluence.     

阿司匹林抑制内皮素-1诱导的大鼠心脏成纤维细胞增殖

目的 探讨阿司匹林（Aspirin）对内皮素-1(ET-1)诱导的大鼠心脏成纤维细胞（CFs）增殖的干预作用及可能机制。方法 经差速贴壁法培养的新生大鼠CFs,随机分为7组：对照组、ET-1组、阿司匹林组、ET-1+ 阿司匹林1、2、5和10 mmol·L-1组。用四氮唑盐（MTT）法测定CFs数目,流式细胞仪检测CFs细胞周期,液体闪烁计数仪测定CFs 3H-脯氨酸掺入率,硝酸还原酶法测定细胞培养上清液中NO含量。结果 与对照组相比,10-7 mol·L-1 ET-1能显著促CFs增值及[3H]-Proline掺入率,降低CFs生成NO2-/NO3-的量（均P < 0.01）,1～10 mmol·L-1 阿司匹林呈浓度依赖性的缓解上述变化（均P < 0.05）; ET-1能显著提高S期细胞百分率（P < 0.01）,10 mmol·L-1 阿司匹林抑制ET-1诱导S期细胞百分率上升（P < 0.01）。结论 阿司匹林抑制ET-1诱导的CFs增殖及胶原合成可能和NO生成有关。     

Curcumin induces apoptosis and inhibits prostaglandin E(2) production in synovial fibroblasts of patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease that is characterized by hyperplasia of the synovial fibroblasts, which is partly the result of decreased apoptosis. This study investigated the mechanisms through which curcumin, a polyphenolic compound from the rhizome of Curcuma longa, exerts its anti-proliferative action in the synovial fibroblasts obtained from patients with RA. Exposure of the synovial fibroblasts to curcumin resulted in growth inhibition and the induction of apoptosis, as measured by MTT assay, fluorescent microscopy and Annexin-V-based assay. RT-PCR and immunoblotting showed that treating the cells with curcumin resulted in the down-regulation of anti-apoptotic Bcl-2 and the X-linked inhibitor of the apoptosis protein as well as the up-regulation of pro-apoptotic Bax expression in a concentration-dependent manner. Curcumin-induced apoptosis was also associated with the proteolytic activation of caspase-3 and caspase-9, and the concomitant degradation of poly(ADP-ribose) polymerase protein. Furthermore, curcumin decreased the expression levels of the cyclooxygenase (COX)-2 mRNA and protein without causing significant changes in the COX-1 levels, which was correlated with the inhibition of prostaglandin E(2) synthesis. These results show that curcumin might help identify a new therapeutic pathway against hyperplasia of the synovial fibroblasts in RA.     

Effect of cytokine-induced soluble ICAM-1 from human synovial cells on synovial cell-lymphocyte adhesion.

The present study was designed to establish (i) the effects of cytokines on soluble ICAM-1 (sICAM-1) production by human synovial cells (SC) and ICAM-1 expression on these cells, and (ii) the effects of sICAM-1 on lymphocyte-SC adhesion. sICAM-1 production was enhanced in parallel with ICAM-1 expression by IL-1 beta, TNF-alpha and IFN-gamma. IL-4 showed no effects on ICAM-1 expression. In contrast with the transient elevation of cell-associated ICAM-1 by IL-1 beta, which peaked 36 h after stimulation and declined thereafter, sICAM-1 continued to accumulate in culture supernatants even after 48 h. Purified sICAM-1 was obtained from a 48 h culture synovial cell supernatant by affinity chromatography using ICAM-1 monoclonal antibody. The purified sICAM-1 significantly inhibited adhesion of lymphocytes and monocytes to cytokine-stimulated synovial cells. These results suggest that sICAM-1 may modulate chronic synovitis by inhibiting ICAM-1-mediated cell-to-cell adhesion.     

TNF-alpha-mediated expression of membrane-type matrix metalloproteinase in rheumatoid synovial fibroblasts.

Degradation of the extracellular matrix plays an important role in rheumatoid articular destruction. Rheumatoid synovial fibroblasts secrete a large amount of matrix-degrading metalloproteinases (MMPs), which initiate tissue damage by proteolytic degradation of collagens and proteoglycans. Cytokines, such as interleukin-1 alpha, -1 beta or tumour necrosis factor (TNF)-alpha, are potent inducers of MMPs in rheumatoid synovial fibroblasts, MMPs are synthesized and secreted as latent pro-enzymes and their activation is achieved by proteolytic cleavage or the propeptide domain at the N-terminus of the molecule. Thus, the interaction of the pro-enzymes with specific activators determines the enzymatic activity in the extracellular space. In the present study, we identified a novel mechanism for the activation of pro-MMP-2, which can be achieved through the interaction of the inflammatory cytokine, TNF-alpha, with synovial fibroblasts. Although MMP-2 is constitutively secreted by synovial fibroblasts as a pro-enzyme, stimulation of fibroblasts by TNF-alpha-induced secretion of MMP-2 in an active form. In support of this result, TNF-alpha stimulation-induced membrane-type matrix metalloproteinase (MT-MMP), a newly identified MMP-2-specific activator on synovial fibroblasts. Cycloheximide analysis demonstrated that protein synthesis may be required for TNF-alpha-mediated MT-MMP expression on synovial fibroblasts. Our results suggest that TNF-alpha induces MMP-2 activation in part by up-regulating MT-MMP expression, thus representing a new mechanism for cytokine-mediated articular destruction in rheumatoid arthritis (RA).     

类风湿性关节炎滑膜成纤维细胞骨保护素和骨形态发生蛋白-2的表达及干预

目的 探讨甲氨蝶呤（MTX）及白细胞介素-6受体（IL-6R）抗体对类风湿关节炎（RA）滑膜成纤维细胞增殖的干预及对骨保护素（OPG）、骨形态发生蛋白-2（BMP-2）的影响.方法 获取RA患者滑膜组织,消化并传代培养成纤维细胞.CCK-8法检测IL-6R抗体、甲氨蝶呤（MTX）对RA滑膜成纤维细胞活性影响;荧光定量（qRT）-PCR检测OPG和BMP-2表达.结果 与空白组相比,MTX组、IL-6R抗体组成纤维细胞的活性受到抑制（F=29.30,34.22,P＜0.05）,MTX联合IL-6R抗体组成纤维细胞的活性显著受到抑制（F=52.04,P ＜0.01）.qRT-PCR显示与空白组相比,IL-6R抗体组、MTX联合IL-6R抗体组OPG、BMP-2的表达均上升（P＜0.05）.与MTK组相比,IL-6R抗体组OPG、BMP-2的表达增加（P＜0.05）.结论 IL-6R抗体单独或联合MTK使用均能明显抑制RA滑膜成纤维细胞的活性,与MTX相比,IL-6R抗体能升高OPG、BMP-2的表达.本研究为应用IL-6R抗体预防和治疗RA关节破坏提供实验依据.     

Histamine-stimulated production of matrix metalloproteinase 1 by human rheumatoid synovial fibroblasts is mediated by histamine H1-receptors

The purpose of this study was to investigate the role of histamine in human rheumatoid synovial fibroblasts in the production of factors responsible for tissue remodelling and cartilage breakdown in rheumatoid arthritis. We examined the effects of histamine of tritiated thymidine incorporation, production of matrix metalloproteinase-1 (MMP-1), histamine H₁-receptor expression, phosphoinositide metabolism and intracellular calcium ion concentration ([Ca²⁺] _i ) in human rheumatoid synovial fibroblasts. Tritiated thymidine incorporation studies demonstrated that histamine markedly stimulated the proliferation of rheumatoid synovial fibroblasts. Immunofluorescence and Northern blot analyses revealed that proMMP-1 production was also stimulated by histamine. The levels of inositol phosphates and [Ca²⁺] _i in the cells were elevated in response to histamine, indicating that the cells expressed histamine H₁-receptors; and Northern blot analysis indicated that these H₁-receptors were up-regulated by histamine. In in situ hybridization, large amounts of histamine H₁-receptor mRNA were also detected in rheumatoid synovial tissue. These results suggest that the interaction between H₁-receptor expression in rheumatoid synovial fibroblasts and histamine secretion by mast cells and macrophages in the affected sites is an important event responsible for tissue remodelling and joint destruction in rheumatoid arthritis.