OBJECTIVE We have previously reported that the coactivation of NF-κB and STAT3 in nonimmune cells, including synovial fibroblasts, enhances the expression of NF-κB target genes and plays a role in chronic inflammation and rheumatoid arthritis (RA). This study was undertaken to examine the role of NF-κB activation in chondrocytes and better understand the pathogenesis of RA. Furthermore, transmembrane protein 147 (TMEM147) was investigated as a representative NF-κB activator in chondrocytes. METHODS Clinical samples from RA patients were analyzed by immunohistochemistry. Specimens obtained from patients with polydactyly were used as control samples. The functional contribution of chondrocytes and TMEM147 to arthritis was examined in several murine models of RA. In vitro experiments (quantitative polymerase chain reaction, RNA interference, immunoprecipitation, and confocal microscopy) were performed to investigate the mechanism of action of TMEM147 in chondrocytes. RESULTS Samples obtained from RA patients and mouse models of RA showed coactivation of NF-κB and STAT3 in chondrocytes (P < 0.001). This coactivation induced a synergistic expression of NF-κB targets in vitro (P < 0.01). Chondrocyte-specific deletion of STAT3 significantly suppressed the development of cytokine-induced RA (P < 0.01). TMEM147 was highly expressed in chondrocytes from RA patient samples and the mouse models of RA. Gene silencing of TMEM147 or anti-TMEM147 antibody treatment inhibited the cytokine-mediated activation of NF-κB in vitro (P < 0.01) and suppressed cytokine-induced RA in vivo (P < 0.01). Mechanistically, TMEM147 molecules acted as scaffold proteins for the NF-κB complex, which included breakpoint cluster region and casein kinase 2, and enhanced NF-κB activity. CONCLUSION These results suggest that chondrocytes play a role in the development of RA via TMEM147-mediated NF-κB activation and indicate a novel therapeutic strategy for RA.

中文翻译：

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软骨细胞通过跨膜蛋白147介导的NF-κB活化在类风湿性关节炎发展中的作用。

目的我们以前曾报道过，包括滑膜成纤维细胞在内的非免疫细胞中NF-κB和STAT3的共激活会增强NF-κB靶基因的表达，并在慢性炎症和类风湿关节炎（RA）中发挥作用。进行这项研究以检查NF-κB激活在软骨细胞中的作用，并更好地了解RA的发病机理。此外，研究了跨膜蛋白147（TMEM147）作为软骨细胞中代表性的NF-κB激活剂。方法采用免疫组织化学方法对RA患者的临床样本进行分析。从多指患者获得的标本用作对照样品。在几种RA小鼠模型中检查了软骨细胞和TMEM147对关节炎的功能性贡献。体外实验（定量聚合酶链反应，RNA干扰，进行了免疫沉淀和共聚焦显微镜检查以研究TMEM147在软骨细胞中的作用机制。结果从RA患者和RA小鼠模型中获得的样品显示，软骨细胞中NF-κB和STAT3共激活（P <0.001）。这种共激活在体外诱导了NF-κB靶标的协同表达（P <0.01）。STAT3的软骨细胞特异性缺失显着抑制了细胞因子诱导的RA的发生（P <0.01）。TMEM147在RA患者样品和RA小鼠模型的软骨细胞中高表达。TMEM147的基因沉默或抗TMEM147抗体处理可在体外抑制细胞因子介导的NF-κB活化（P <0.01），并在体内抑制细胞因子诱导的RA（P <0.01）。从机制上讲，TMEM147分子充当NF-κB复合体的支架蛋白，其中包括断点簇区域和酪蛋白激酶2，并增强了NF-κB活性。结论这些结果表明，软骨细胞通过TMEM147介导的NF-κB活化在RA的发展中起作用，并为RA提出了一种新的治疗策略。