【摘要】 目的：类风湿关节炎(rheumatoid arthritis,RA)是一种慢性自身免疫性疾病，微RNA已被证实在RA中起重要作用。微RNA-124a(microRNA-124a,miR-124a)在RA滑膜细胞中具有抗增殖及抗炎作用。本研究探讨过表达miR-124a对胶原诱导关节炎(collagen-induced arthritis,CIA)小鼠关节炎的影响及其可能的作用机制。方法：构建牛源性II型胶原和完全弗氏佐剂诱导的DBA/1小鼠CIA模型。初次免疫后第28天(D28)，将CIA模型小鼠随机分成模型组、miR-124a治疗组和阴性对照(NC)组，分别在小鼠尾根部皮内注射生理盐水、miR-124a agomir、miR-124a agomir阴性对照，每3 d注射1次，共注射4次。观察并评估小鼠关节肿胀程度及关节炎指数。初次免疫后第63天(D63)，处死小鼠获取踝关节滑膜组织。采用HE染色观察小鼠关节滑膜细胞增殖、炎症细胞浸润、血管翳、骨质侵蚀情况；TUNEL染色检测滑膜组织细胞凋亡情况；定量反转录PCR检测滑膜组织中miR-124a、磷脂酰肌醇3-激酶催化亚基α(phosphatidylinositol-3-kinase catalytic subunit alpha,PIK3CA)基因及下游基因Bcl-2、Bax mRNA的表达；免疫组织化学检测滑膜组织中PIK3CA、Bcl-2、Bax蛋白质的表达。结果：D28时，DBA/1小鼠足爪开始出现不同程度的肿胀，表明CIA模型构建成功。初次免疫后第48天(D48),miR-124a治疗组小鼠的足爪仅有轻微红肿，而模型组、NC组足爪红肿明显。初次免疫后第51、53、59、62天(D51、D53、D59、D62),miR-124a治疗组小鼠关节炎指数较NC组明显下降(均P<0.05)。D63时，miR-124a治疗组小鼠的滑膜细胞增殖、炎症细胞浸润、血管翳及骨质侵蚀评分均较模型组和NC组明显降低(P<0.05或P<0.01)，细胞凋亡增加(P<0.01或P<0.001），滑膜组织中miR-124a、Bax的表达水平明显上调且PIK3CA、Bcl-2的表达水平明显下调(P<0.05或P<0.01或P<0.001),Bcl-2/Bax值明显下降(P<0.01或P<0.001)。结论：过表达miR-124a可减轻CIA小鼠关节炎，其机制可能是miR-124a靶向调控PIK3CA及其下游通路，促进滑膜细胞凋亡，抑制滑膜细胞增殖。更多还原

【Abstract】 Objective: Rheumatoid arthritis(RA) is a chronic autoimmune disease. MicroRNA has been shown to play an important role in RA. MicroRNA-124a(miR-124a) has antiproliferative and anti-inflammatory effects in RA fibroblast synovial cells. This study aims to explore the effects of miR-124a overexpression on arthritis in collagen-induced arthritis(CIA) mice and the underlying mechanisms.Methods: Bovine type II collagen and complete Ferris adjuvant were used to induce CIA model from DBA/1 mice. Twenty-eight days after initial immunization(D28), CIA mice were randomly divided into a model group, a miR-124a treatment group, and a negative control(NC) group. Physiological saline, miR-124a agomir, and miR-124a agomir NC were injected into the skin at the tail root of mice every 3 days for 4 times, respectively.The degree of joint swelling and arthritis index of mice were recorded accordingly. Sixtythree days after initial immunization(D63), the mice were sacrificed to obtain the synovial tissue of ankle joint. HE staining was used to observe the proliferation of synovial cell,infiltration of inflammatory cell, pannus, and bone erosion of synovial tissues; TUNEL staining was used to detect cell apoptosis; qRT-PCR was used to detect the m RNA expression of miR-124a, phosphatidylinositol-3-kinase catalytic subunit alpha(PIK3CA)and its downstream genes Bcl-2 and Bax. Immunohistochemistry was used to detect the protein expression of PIK3CA, Bcl-2, and Bax protein in synovial tissues of each group.Results: Different degrees of swelling presented in the paws of DBA/1 mice at D28, which indicated the CIA model was constructed successfully. Forty-eight days after initial immunization(D48), the paws of mice in the miR-124a treatment group were only slightly red and swollen, while the paws of mice in the model group and the NC group were obviously red and swollen. The arthritis index of mice in the miR-124a treatment group were decreased significantly compared to the NC group at D51, D53, D59, and D62(51,53, 59, 62 days after initial immunization)(all P<0.05). Sixty-three days after initial immunization(D63), HE staining indicated that the scores of synovial cell proliferation,inflammatory cell infiltration, synovial pannus, and bone erosion were significantly reduced in the miR-124a treatment group(P<0.05 or P<0.01), while cell apoptosis was increased in the miR-124a treatment group compared with the model group and NC group(P<0.01 or P<0.001). Besides, the expression of miR-124a and Bax in the synovial tissue in miR-124a treatment group was significantly higher than those in the model group and NC group(P<0.01 or P<0.001), while the expressions of PIK3CA and Bcl-2 were decreased(P<0.05 or P<0.01 or P<0.001), and the ratio of Bcl-2 to Bax was significantly decreased(P<0.01 or P<0.001).Conclusion: Overexpression of miR-124a can reduce arthritis in CIA mice bacause it could promote synovial cell apoptosis and inhibit synovial cell proliferation via targeting PIK3CA and regulating its downstream pathways.更多还原