p204/IFI16介导的免疫调控在急性肾损伤中的作用与机制

Pattern-recognition receptors (PRRs)-mediated immunoregulation and inflammatory response play critical roles in acute kidney injury (AKI), and take center stage in the study of AKI. Mouse p204 and human IFI16 are homologous proteins due to the similarity in structure and function. As a member of DNA sensors family in PRRs, p204/IFI16 play important roles in a variety of physiologic and disease processes. However, the expression of p204/IFI16 in kidney and the role of p204/IFI16 in the pathogenesis of AKI are still unknown. Our preliminary studies showed that there is a physiological expression of p204/IFI16 in renal parenchymal cells, which were up-regulated in ischemia and nephrotoxic drug induced AKI. p204 deficiency protected against kidney injury induced by renal ischemia-reperfusion in mice. Therefore, the present study is designed to explore the role of p204/IFI16 in AKI using p204 knockout mice and cell biology approaches, among others. We will further investigate the immune regulatory mechanisms of p204/IFI16 in AKI, including p204/IFI16-repressed anti-inflammatory factor progranulin (PGRN) and p204/IFI16-mediated DNA-sensing pathway. This study will expand new knowledge of biological function of p204/IFI16 and provide new target and idea for the prevention and treatment of AKI.

模式识别受体（PRRs）介导的免疫调控和炎性反应在急性肾损伤中发挥关键作用并成为该领域的研究热点。小鼠p204与人IFI16是结构与功能相似的同源蛋白（p204/IFI16）并作为PRRs中DNA感受器分子家族成员在多种病理生理过程中具有重要作用，但p204/IFI16在肾脏中的表达及在急性肾损伤中的作用机制尚不清楚。我们前期工作中首次证实p204/IFI16在肾脏实质细胞中表达并在缺血和药物所致急性肾损伤中表达显著升高，p204敲除可保护肾缺血再灌注诱导的小鼠肾损伤。为此，本课题将运用p204敲除小鼠和细胞生物学等方法，明确p204/IFI16在急性肾损伤中的作用，并探讨p204/IFI16负调控抑炎因子PGRN和通过DNA感应途径在急性肾损伤中的免疫调控机制。此研究将拓展对p204/IFI16生物学功能的新认识，为急性肾损伤防治提供新的靶点和思路，具有重要的理论意义。

人类IFI16及其小鼠p204被认为是一类识别外源性DNA的潜在的模式识别受体，在DNA病毒感染引起的固有免疫应答中具有重要作用。本研究旨在证实p204/IFI16在急性肾损伤（AKI）中的作用与分子调控机制。本研究利用缺血再灌注诱导的AKI小鼠模型，发现p204在AKI小鼠肾脏肾小管上皮细胞的细胞核中表达显著升高；而在体外模拟AKI的肾小管上皮细胞系HK-2中也印证了IFI16表达上升。使用p204系统性敲除小鼠明确了p204基因缺失可有效抑制缺血再灌注诱导的肾小管上皮细胞损伤、肾功能下降和肾脏炎症应答；抑制HK-2细胞中IFI16表达则显著改善缺氧/复氧引起的细胞凋亡和炎性分子表达。使用p204肾小管上皮细胞特异性敲除小鼠，证实肾小管上皮细胞中的p204缺失在AKI中发挥主要作用。AKI小鼠肾皮质转录组分析及体内、体外实验证实p204/IFI16通过介导肾小管上皮细胞铁死亡途径，促进肾脏损伤，进而导致肾脏炎症性免疫应答。此外，缺氧/复氧处理的HK-2细胞中IFI16与DNA损伤相关标志物γ-H2AX共定位，提示p204/IFI16可能通过识别损伤DNA启动铁死亡。分子机制研究发现p204/IFI16可促进AKI压力下DNA损伤修复相关ATM磷酸化水平，IFI16介导铁死亡依赖于ATM信号途径的活化。本研究首次发现了p204/IFI16可能结合AKI病理条件下肾小管上皮细胞中受损DNA，进而激活ATM，介导铁死亡，引起肾脏损伤和炎症应答的新功能与分子机制，为AKI防治提供新的靶点和思路，同时拓展了疾病过程中铁死亡的新型调控机制，具有重要的理论意义。