HMGB1介导的自噬调控巨噬细胞极化在类风湿关节炎发展中的作用和机制

Rheumatoid arthritis(RA) is an M1 macrophage-dominant chronic inflammatory disease. In addition, macrophage autophagy level can regulate its polarization progress to achieve different macrophage biological effects. Our preliminary results indicate that the overexpression of HMGB1 in serum and joints can increase the autophagy level in rheumatoid arthritis synovial fibroblasts（RASF） to facilitate RASF to secrete matrix metalloproteinase and inflammatory cytokines. It has not been reported previously that HMGB1 can induce macrophage autophagy and regulate its polarization. In terms of flow cytometry, western blot, immunohistochemistry, mice model with a macrophage-specific knockout of the autophagy gene Atg5, this project aims to analyze the monocyte /macrophage autophagy level of blood and synovial tissue from RA patients, to reveal the relationship between the M1/M2 macrophage ratio and the level of HMGB1, the relationship between the M1/M2 macrophage ratio and the disease severity, then investigate the key receptor and signal transduction pathway of HMGB1 regulating the monocyte /macrophage autophagy process. Also, we investigate the effects, target molecules and signal transduction pathway of the macrophage polarization process regulated by autophagy. Next, we plan to demonstrate the pathogenicity of HMGB1-mediated autophagy in mice arthritis model. We hope to elucidate the role and mechanism of HMGB1 in the immunopathological damage of RA and to provide new targets for treatment of RA.

类风湿关节炎（RA）是M1型巨噬细胞主导的慢性炎症性关节炎。文献报道巨噬细胞自噬可调控其极化的方向，发挥不同生物学效应。我们前期研究发现，HMGB1在RA患者血清和病损关节高表达，诱导滑膜成纤维细胞自噬，促进细胞分泌蚀骨基质蛋白酶和炎性因子等。有关HMGB1诱导巨噬细胞自噬，调控巨噬细胞极化及在RA中的作用和机制均未见报道。本课题拟采用流式细胞术、免疫印迹、免疫组化、巨噬细胞条件敲除Atg5小鼠等技术和材料，首先分析RA患者血液和病损滑膜组织单核/巨噬细胞自噬水平、M1/M2型巨噬细胞比例与HMGB1水平、疾病活动度等的关联；继而探讨HMGB1对单核/巨噬细胞自噬水平的调控及作用的关键受体和信号通路；再研究自噬对巨噬细胞极化的影响及关键信号通路；最后通过体内外实验探究HMGB1介导巨噬细胞自噬对小鼠关节炎模型的致病作用及机制。为HMGB1在RA免疫病理损伤提供新的理论依据和干预靶点。

类风湿性关节炎（Rheumatoid arthritis,RA）是M1型巨噬细胞主导的慢性炎症性关节炎。文献报道巨噬细胞自噬可调控其极化的方向，发挥不同生物学效应。我们先前的研究表明HMGB1-PAMP复合物可以直接诱导小鼠关节滑膜炎症，病理表现为关节滑膜增厚，滑膜成纤维细胞过度增殖和淋巴细胞浸润，提示HMGB1-PAMP复合物诱导RASFs的形成是RA发生的可能机制之一，有关HMGB1诱导巨噬细胞自噬，调控巨噬细胞极化及在RA中的作用和机制均未见报道。本课题首先通过检测活动性RA患者血液和病损滑膜组织单核/巨噬细胞自噬水平、M1/M2型巨噬细胞比例与HMGB1水平，初步明确了HMGB1诱导巨噬细胞自噬与RA疾病活动度间存在相关关系，通过体外实验进一步探明了HMGB1通过结合巨噬细胞表面TLR-4受体，促使巨噬细胞分泌大量促炎性细胞因子，最终加速RA病人的病情发展。本课题研究证实了HMGB1可以在实验动物体内诱导实验性关节炎，免疫组化染色显示大量促炎性细胞过度增殖，软骨组织基质发生严重破坏，软骨细胞发生退化、皱缩，促炎性细胞因子表达明显上调。