目的：探究性别决定区Y框蛋白9（sex determining region Y-box transcription factor 9, SOX9）通过抑制微小核糖核酸（micro-ribonucleic acid, miRNA）204和211对类风湿关节炎（rheumatoid arthritis, RA）成纤维样滑膜细胞（fibroblast-like synoviocyte, FLS）功能的影响及其潜在机制。方法：通过Ⅱ型胶原诱导建立胶原诱导性关节炎（collagen-induced arthritis, CIA）模型。使用Ⅳ型胶原酶消化CIA小鼠膝关节滑膜组织分离FLS。采用实时荧光定量聚合酶链反应（quantitative real-time polymerase chain reaction, qPCR）检测FLS中Sox9的表达水平。使用小干扰核糖核酸（small interfering ribonucleic acid, siRNA）抑制Sox9的表达，通过CCK-8法和5-乙炔基-2’-脱氧尿嘧啶核苷（5-ethynyl-2’-deoxyuridine, EdU）染色法检测细胞增殖能力；细胞衰老β半乳糖苷酶（senescence-associated β-galactosidase, SA-β-gal）染色分析细胞衰老，qPCR检测细胞周期蛋白依赖性激酶抑制因子（cyclin-dependent-kinase inhibitor, CKI）p16、p21、p53和miR-204、miR-211的表达。采用HDOCK在线网站（http://hdock.phys.hust.edu.cn/）分析miR-204、miR-211与SOX9的结合能力。结果：与正常小鼠FLS相比，CIA-FLS中SOX9的信使核糖核酸（messenger ribonucleic acid, mRNA）表达显著增高。敲低Sox9可促进细胞衰老，从而抑制FLS增殖。miR-204、miR-211均可与SOX9稳定结合。在CIA-FLS中敲低Sox9可促进miR-204/-211的表达。结论：SOX9可通过下调miR-204/-211的表达，促进CIA-FLS细胞增殖并抑制其衰老。

Objective To investigate the effect of sex determining region Y-box transcription factor 9 (SOX9) on the function of fibroblast-like synoviocyte (FLS) in rheumatoid arthritis (RA) by inhibiting micro-ribonucleic acid (miRNA)-204 and -211, and to explore the underlying mechanism. Methods A collagene-induced arthritis (CIA) model was established by type Ⅱ collagen induction. FLS were isolated from the knee joint synovial tissue of CIA mice by digestion with type Ⅳ collagenase. The expression level of Sox9 in FLS was detected by quantitative real-time polymerase chain reaction (qPCR). Small interfering ribonucleic acid (siRNA) was used to inhibit Sox9 expression, and cell proliferation was assessed by CCK-8 assay and 5-ethynyl-2’-deoxyuridine (EdU) staining. Cell senescence was analyzed by senescence-associated β-galactosidase (SA-β-gal) staining, and the expression of cyclin-dependent kinase inhibitor (CKI) p16, p21, p53 and miR-204, miR-211 was detected by qPCR. The HDOCK online server (http://hdock.phys.hust.edu.cn/) was used to analyze the binding potential between miR-204/miR-211 and SOX9. Results Compared with FLS from normal mice, the messenger ribonucleic acid (mRNA) level of SOX9 was significantly increased in CIA-FLS. Knock down of Sox9 can promote cell senescence, thereby inhibiting FLS proliferation. Both miR-204 and miR-211 could stably bind to SOX9. Knockdown of Sox9 in CIA-FLS can increase the expression of miR-204/-211. Conclusions SOX9 can promote the proliferation of CIA-FLS and inhibit their senescence by down-regulating the expression of miR-204 and miR-211.