DNA识别器cGAS对RA成纤维样滑膜细胞异常活化和增殖的调控及其机制

Persisting synovial inflammation play a critical role in the progress of joint destruction of rheumatoid arthritis (RA), and abnormal activation of fibroblast-like synoviocytes (FLS) in the synovial intimal lining contributing to perpetuate inflammation by producing cytokines and proteases. In recent years, it has been shown that double stranded DNA(dsDNA) participate in modulation of immune responses and the pathogenesis of some autoimmune diseases, but it’s role in pathogenesis of RA remain unclear. We found that the expression of dsDNA and cytosolic dsDNA sensor cGAMP synthetase (cGAS) in synovium and fibroblast like synoviocytes synoviocytes (FLS) of RA patients was higher compared with osteoarthritis patients. Treatment with dsDNA increased secretion of proinflammatory cytokines and MMP in FLS from RA patients, and suppression of cGAS by shRNA down-regulated dsDNA-induced proinflammatory cytokines secretion and proliferation of RA FLS. These suggest that cGAS might have an important role in the dsDNA-induced activation and proliferation of RA FLS. Therefore, based on our previous studies, we will further determine the role of increased intracellular dsDNA and cGAS in regulating cytokines expression, MMP secretion and proliferaton of RA FLS, as well as its signal mechanisms. We will also identify the in vivo inhibitory effect of cGAS shRNA on severity of arthritis in mice with collagen-induced arthritis (CIA). Our results will reveal the role of dsDNA via cGAS signal pathway in synovitis and joint destruction, and provide evidence for new therapeutic target of RA.

关节滑膜持续炎症是类风湿关节炎（RA）病情恶化和关节破坏的关键因素之一，成纤维样滑膜细胞（FLS）异常活化和增殖在滑膜炎症发生发展中起重要作用。近年发现异常增多的胞浆内双链DNA(dsDNA)诱导某些自身免疫性疾病发生，但在RA发病中的作用尚无报道。我们前期发现RAFLS胞浆内dsDNA及其识别器cGAMP合成酶（cGAS）表达高于骨关节炎患者，dsDNA转染RAFLS可促增殖和炎症因子分泌，干扰cGAS表达可抑制该作用，提示cGAS可调控胞内dsDNA诱导的FLS异常活化。基于以往工作基础，本课题拟证实FLS胞内增多的dsDNA对其活化和增殖的影响，明确cGAS对dsDNA诱导的FLS活化及增殖的调控作用及机制；利用胶原诱导关节炎模型，观察体内抑制cGAS表达对FLS活化和增殖的影响及关节损害的改善作用，旨在阐明cGAS对RA滑膜炎症和增生的调控作用，为研制新型RA治疗药物提供理论基础。

关节滑膜持续炎症是类风湿关节炎（RA）病情恶化和关节破坏的关键因素之一，成纤维样 滑膜细胞（FLS）异常活化在滑膜炎症发生发展中起重要作用。近年研究发现核酸（包括外源性及自身核酸）能够被固有免疫系统模式识别受体识别，直接促发机体固有免疫反应。异常增多的胞浆内双链DNA(dsDNA)诱导某些自身免疫性疾病发生，但在RA发病中的作用尚无报道。我们主要研究发现1）胞浆内dsDNA在RA细胞及组织中的表达高于创伤对照组及骨关节炎对照组，TNF-α可促进RAFLS胞内dsDNA表达，且RA滑膜dsDNA的表达与滑膜炎症程度相关；2）dsDNA转染RA FLS可促进细胞炎症因子基因表达及分泌增高；3）DNaseII过表达可减少胞内dsDNA含量，且过表达DNaseII可抑制细胞炎症因子分泌；4）dsDNA识别器cGAS 在RA细胞及组织中的表达高于创伤对照组及骨关节炎对照组，TNF-α及dsDNA可促进cGAS高表达，干扰cGAS及STING水平可抑制dsDNA诱导的细胞因子分泌；5）干扰cGAS及STING对下游NF-κB及IRF3的作用；6）dsDNA与JETPI共同注射入DBA及C57小鼠，诱导关节炎，未见明显关节炎症状，但病理可见炎症改变。本课题证实了FLS胞内增多的dsDNA对其分泌炎症因子的影响，其可能通过DNase2-dsDNA-c GAS/STING-NF-κB/IRF3通路发挥作用。本研究阐明了dsDNA及cGAS对RA滑膜炎症的调控作用为研制新型RA治疗药物提供理论基础。