STAT3/MAVS/NLRP3炎症小体信号通路在足细胞损伤中的作用

Podocyte injury contributes to the development and progression of many glomerular diseases and CKDs. Accumulating evidence indicated that inflammation serves as an important contributor of podocyte injury. Emerging evidence demonstrated that MAVS, an innate immunity-related protein is also involved in the pathogenesis of non-infectious inflammation. Our preliminary data revealed that several insults could similarly induce MAVS upregulation and STAT3 phosphorylation in podocytes. Overexpression of MAVS induced podocyte apoptosis in line with nephrin reduction. Interestingly, bioinformatics analysis showed three STAT3 binding sites in MAVS promoter region, and inhibition of STAT3 phosphorylation down-regulated MAVS mRNA expression, suggesting that transcription factor STAT3 may directly drive MAVS transcription. Moreover, studies from other groups reported that MAVS has a role in activating NLRP3 inflammasome in other cell types. Consistent with these reports, we also found that overexpression of MAVS up-regulated NLRP3 protein expression in podocytes. Thus, we hypothesized that STAT3/MAVS/NLRP3 inflammasome signaling pathway might be attributable to the pathogenesis of podocyte injury. In the present proposal, using in vitro cell and in vivo animal models, we will fully investigate the contribution of STAT3/MAVS/NLRP3 inflammasome signaling pathway in podocyte injury, which will offer new insights into the therapy of podocytopathy and CKD.

足细胞损伤是引发肾小球疾病及CKD的重要病理因素，而炎症是导致足细胞损伤的重要机制。研究显示抗病毒蛋白MAVS 亦可介导固有细胞的非感染性炎症，然而在足细胞中尚无研究报道。本课题组前期研究发现，多种刺激均可上调足细胞MAVS表达及转录因子STAT3磷酸化，高表达MAVS可诱导足细胞Nephrin表达下降及细胞凋亡；生物信息学分析发现MAVS启动子区有3个转录因子STAT3结合位点，且抑制STAT3磷酸化可下调MAVS表达，提示STAT3是MAVS的直接调控因子。此外，有研究显示MAVS在其它细胞可活化NLRP3炎症小体，我们预实验结果亦显示在足细胞高表达MAVS可增加NLRP3表达。本课题拟从动物、细胞及分子水平探讨STAT3/MAVS/NLRP3炎症小体信号通路在足细胞损伤过程中的活化及作用，为足细胞损伤及CKD防治提供新的理论依据及干预靶点。

足细胞损伤是引发肾小球疾病及慢性肾脏病的重要病理因素，而炎症是导致足细胞损伤的重要机制。研究显示抗病毒蛋白MAVS亦可介导固有细胞的非感染性炎症，然而在足细胞中尚无研究报道。本课题组研究发现，多种刺激均可激活人足细胞内MAVS信号通路，高表达MAVS可诱导人足细胞损伤，表现为podocin蛋白表达下降及细胞凋亡。在小鼠体内转染MAVS高表达质粒，结果显示，高表达MAVS可以显著加重阿霉素造成的蛋白尿、肾小球损伤、足细胞损伤以及NLRP3炎症小体活化。为了验证高表达结果，本课题组又利用CRISPR/Cas9新技术构建MAVS基因组敲除质粒，在小鼠体内转染MAVS的敲除质粒，结果显示，低表达MAVS可以显著减轻阿霉素造成的蛋白尿，肾小球损伤显著减轻，蛋白尿管型明显减少以及NLRP3炎症小体活化减轻。随后又构建了MAVS敲除小鼠醛固酮刺激模型，发现MAVS敲除小鼠可以显著减轻醛固酮引起的蛋白尿。根据以上实验结果，说明MAVS确实参与阿霉素以及醛固酮引起的肾脏足细胞损伤，减少MVAS可以显著减轻阿霉素或者醛固酮引起的肾脏足细胞损伤。