NRAGE对类风湿关节炎滑膜炎症和骨破坏的调控作用及机制研究

Rheumatoid arthritis is a chronic inflammatory disease that results in synovial inflammation and subsequent destruction of bone. It is urgent for us to look for new targets to prevent and cure RA. NRAGE, an important adaptor protein, has been shown to play critical roles in many aspects of cellular events and physiologic functions. However, its role in RA remains unknown. Our preliminary data showed that NRAGE maybe play a key regulatory role in synovial inflammation and destruction of bone. The main evidences supporting this hypothesis are as follows: ①NRAGE knockdown increased the cytokine mRNA expression in TNFɑ-stimulated MH7A cells; ②NRAGE-deficient osteoclasts exhibited enhanced differentiation and bone resorption activity; ③The expression level of NRAGE was lower in the synovial tissues of CIA rat than that in the normal control; ④NRAGE knockdown in the articular cavities of CIA rats using adenovirus plasmids carrying small hairpin NRAGE interference showed significantly aggravated synovial inflammation and destruction of bone. Collectively, these studies demonstrated for the first time that NRAGE probably involved in the regulation of RA pathogenesis, however, its mechanism remains unknown. This project will clarify the roles of NRAGE in RA, using NRAGE knockout mice with CIA and cultured rheumatoid FLS, and subsequently investigated the possibly mechanisms. This study will not only greatly help us to understand the complex mechanisms of RA pathogenesis but also provide a novel clue for prevention and treatment of RA.

RA病程复杂，发病机制尚未阐明，寻找新的调控基因和防治靶标仍是目前亟待解决的问题。NRAGE作为细胞内重要接头蛋白，已被证明可通过不同的机制调控机体多种生理病理过程，但其与RA的关系尚未见任何报道。我们前期研究结果发现: ①滑膜成纤维细胞MH7A沉默NRAGE后，TNFɑ诱导的炎性因子表达上调；②体外破骨细胞分化实验表明，NRAGE敲除可明显增强破骨细胞的分化能力和骨吸收活性；③NRAGE在CIA大鼠滑膜中的表达较正常对照组明显下降；④CIA大鼠关节局部沉默NRAGE后，滑膜炎症及骨侵蚀明显加重。上述结果提示：NRAGE可能是新的RA调控分子，参与调控了RA滑膜炎症和骨破坏等重要病理学环节，但其具体作用机制并不清楚。本项目拟以胶原诱导的敲除小鼠和滑膜成纤维细胞为材料，多种方法综合运用，明确NRAGE对RA的调控作用，并从动物、细胞和分子水平揭示其可能的机制，为寻找新的防治靶标提供思路。

类风湿关节炎（Rheumatoid arthritis, RA）病程复杂，发病机制尚未阐明，寻找新的调控基因和防治靶标仍是目前亟待解决的问题。NRAGE隶属于MAGE（黑色素瘤抗原）家族，是细胞内重要的多功能接头蛋白，已被证明可通过不同的机制调控机体多种生理病理过程，但其与RA的关系尚未见任何报道。本项目基于NRAGE敲除小鼠，构建了胶原诱导性关节炎模型（collagen-induced arthritis，CIA）和胶原抗体诱导性关节炎模型（Collagen antibody-induced arthritis, CAIA），通过关节炎指数评分、足爪厚度测量、血清和踝关节炎性因子检测、病理学评分和影像学分析等多种评价指标，比较分析了NRAGE敲除组和野生组RA表型，发现敲除组CIA和CAIA发病率显著降低，RA病理改变明显改善，确证NRAGE正调控RA病理进程。机制研究发现，敲除型CIA小鼠踝关节、脾脏和腹腔中M2型巨噬细胞比例明显上调；体外巨噬细胞极化模型亦显示，NRAGE敲除能够明显促进巨噬细胞向M2方向极化。分子水平研究进一步表明，NRAGE敲除能够上调M2极化中PPARγ及其靶基因的表达。综上所述，NRAGE基因缺失能够通过上调PPARγ表达以促进巨噬细胞M2极化，进而抑制RA病理进程。该发现不仅拓宽了NRAGE基因的功能领域，而且有助于阐明RA发病机理，为该疾病防治提供新思路。