NLRP3炎性小体通路调控足细胞抗原提呈功能在狼疮肾炎中的作用机制研究

Lupus nephritis (LN) is the most common severe internal organ involvement in systemic lupus erythematosus. We previously reported that NLRP3 inflammasome pathway was highly activated in podocytes in LN and IgG from diseased mice sera was the major component responsible for NLRP3 inflammasome pathway activation. However, the pathogenic IgG that activates NLRP3 inflammasome pathway and how does NLRP3 inflammasome pathway activation contribute to LN progression remain to be elucidated. Our preliminary data showed that dsDNA-anti-dsDNA antibody activated podocytes NLRP3 inflammasome pathway which could be blocked by NLRP3 selective inhibitor MCC950. In addition, recent studies showed that podocytes could act as antigen presenting cell (APC). And we further found abundant expression of MHC-II on podocytes from LN biopsies and diseased lupus-prone mice and that NLRP3 inflammasome pathway activation by dsDNA-anti-dsDNA antibody could also enhance the expression of MHC-II and CD80 on podocytes. Based on these results, our study aims to explore how does dsDNA-anti-dsDNA antibody activate podocytes NLRP3 inflammasome pathway and the role of NLRP3 inflammasome pathway regulation on podocytes antigen presentation function and progression of LN so as to clarify the role of podocyte in the pathogenesis of LN.

狼疮肾炎(LN)是系统性红斑狼疮最常见的严重器官损害。我们既往报道LN足细胞NLRP3炎性小体通路显著活化，发病小鼠血清IgG是活化NLRP3炎性小体的关键成分。但活化足细胞NLRP3炎性小体通路的致病性抗体及足细胞NLRP3炎性小体通路活化参与LN进展机制尚不明确。本课题预实验结果显示dsDNA-抗dsDNA抗体活化足细胞NLRP3炎性小体通路并被NLRP3抑制剂MCC950抑制。最近研究发现足细胞具有抗原提呈细胞功能。进一步探索发现LN患者及发病狼疮小鼠肾脏足细胞高表达MHC-II且dsDNA-抗dsDNA抗体活化NLRP3炎性小体显著升高足细胞MHC-II及CD80。基于以上发现，本课题拟通过体内外实验探索dsDNA-抗dsDNA抗体参与活化足细胞NLRP3炎性小体通路的具体机制，及NLRP3炎性小体通路活化增强足细胞抗原提呈功能在LN进展的作用机制，进一步阐明足细胞在LN中的作用。

研究背景：足细胞损伤促进狼疮肾炎（LN）蛋白尿产生及进展。既往研究表明LN足细胞NLRP3炎性小体活化，但其调控机制仍不完全明确。坏死性凋亡是新发现的细胞死亡形式。研究报道该通路RIP3分子可直接介导炎症反应。但RIP3是否调控足细胞NLRP3炎性小体且NLRP3炎性小体是否增强足细胞抗原提呈功能仍不明确。.主要研究内容：收集临床及狼疮小鼠肾组织，行免疫荧光染色探讨足细胞RIP3-NLRP3、MHC-II、CD80表达变化。进而采用RIP3抑制剂GSK872干预MRL/lpr狼疮小鼠，收集小鼠肾脏进行病理染色，观察肾脏组织病理变化、免疫复合物沉积；免疫荧光染色观察肾脏足细胞NLRP3炎性小体活化情况；分离肾小球制备单细胞悬液进行流式细胞术分析肾脏足细胞NLRP3炎性小体活化水平。体外采用Protein A+G法去除血清中IgG，或采用dsDNA-抗dsDNA抗体刺激足细胞，探讨抗dsDNA等致病性自身抗体通过FcRn活化足细胞NLRP3炎性小体的机制。.关键结果：发现致病性自身抗体如抗dsDNA抗体可通过FcRn进入足细胞，进而活化RIP3-NLRP3炎性小体通路，加重肾小球炎症进展；NLRP3炎性小体活化增强了足细胞MHC-II、CD80分子的表达；狼疮患者血清处理的足细胞可进一步活化狼疮患者来源的CD4+T细胞，而活化的CD4+T细胞反过来造成足细胞骨架重构，加重足细胞损伤。靶向抑制RIP3显著抑制肾脏及足细胞RIP3-NLRP3炎性小体通路，降低MHC-II、CD80表达水平，减轻肾损伤及蛋白尿。.结论：致病性自身抗体通过FcRn活化足细胞RIP3-NLRP3炎性小体通路，并增强足细胞抗原提呈相关分子表达水平，促进狼疮肾炎进展。