AIM2在乙肝病毒相关性肾小球肾炎发病中的分子作用机制

Hepatitis B virus associated glomerulonephritis (HBV-GN) is an immune complex-mediated disease. Recent studies found the virus particles within the glomeruli and renal tubules in HBV-GN，in which the HBV-DNA was detected in cytoplasm. The view that "HBV may replication within the renal tissue and damage the tissue directly" was proposed by some researchers, but the mechanism remains unclear, that is, whether the virus is a "passenger" or "driver" in pathegenesis of HBV-GN?.The exciting discovery of absent in melanoma 2 ( AIM2 ) was a landmark in immunology. AIM2 is an interferon-inducible HIN-200 family member，which can be activated by cytoplasmic exogenous dsDNA. Recognition and activation of AIM2 by cytoplasmic dsDNA results in direct activation of Caspase-1, which subsequently induces secretion of potent pro-inflammatory cytokines (such as IL) and pyroptosis, a form of programmed cell death. Since HBV is dsDNA virus，our project is designed to combine cytological and histological experiments to identify expression of AIM2、Caspase-1、IL-1βand IL-18 in HBV infected renal tissue and cell. .Our preliminary experiments showed that the expressions of AIM2 in HBV-GN group was significantly higher than those in control group，and same with the expression of caspase-1. The expression of IL-1β was positive correlated with Caspase-1, and the latter was positive correlated with AIM2 in HBV-GN group. As an important inflammasome component that senses potentially dangerous cytoplasmic HBV-DNA, AIM2 leads to activation of the ASC pyroptosome and Caspase-1，induces the formation of AIM2-caspase-ASC inflammasome complexes, and causes the release of Inflammatory mediators，making the injury of renal tissue directly. .Our research aims to to reveal the molecular mechanism of AIM2 in HBV-GN，exploring weather AIM2 can be activated by HBV-DNA，and confirm the formation of inflammasome complexes. The final goal of our study is to explore its potential application of AIM2 inflammasome complexes as potential clinical therapeutic target in HBV-GN..Floating AIM2 detection in urine is in order to become a new index of HBV-GN clinical test.

乙肝病毒相关性肾炎（HBV-GN）肾小球及小管细胞内发现病毒样颗粒并检测到病毒DNA,因此有学者提出“HBV在肾组织内直接感染致病”观点,但一直未能阐明损伤机制。病毒究竟是“过客”还是“主角”?黑色素瘤缺乏因子(AIM2)是近年来免疫界的重大发现，能识别胞浆内dsDNA进而活化Caspase-1，形成炎性复合体，介导炎症因子的加工与分泌。HBV是dsDNA病毒，课题拟通过细胞结合组织学实验检测HBV-GN肾小球固有细胞内AIM2及下游因子表达（预实验证实肾组织内HBV-DNA与AIM2激活、Caspase-1表达等呈正相关），再应用AIM2siRNA进行逆向实验,最终证实HBV DNA通过激活传感器AIM2启动胞浆内炎性复合体形成、释放炎性因子，揭示HBV直接引起肾损伤的作用机理,使AIM2炎性体成为治疗HBV-GN等疾病的可能目标；同时进行患者尿液AIM2检测以期成为临床检验助诊新指标。

乙肝病毒相关性肾小球肾炎(HBV-GN)是HBV感染主要的肝外表现之一，免疫复合物引起的肾组织损伤是HBV-GN目前较为公认的发病机制。而现今免疫电镜对HBV-GN肾组织的超微形态结构观察发现肾固有细胞内HBV的存在，以及PT-PCR检测技术在HBV-GN肾组织内直接检测到HBV-DNA的复制，均提示除HBV抗原-抗体复合物在肾小球沉积等经典免疫复合物致病途径外，还应该考虑HBV直接感染所致的组织损伤可能也参与了发病。据此有学者提出“HBV可在肾组织直接感染、复制及损伤”的观点。虽有上述研究和证据支持这一观点，却都仅为形态学观察结果或分析推论，少有在分子水平阐明病毒的直接损伤机制的相关研究，因此仍需深入探讨，以揭示HBV病毒本身在疾病发生的分子作用通路。.胞浆内DNA是机体发生免疫应答的一个强力激发因子，免疫反应过程中所涉及的下游信号通道已被广泛研究和揭示，但是机体对细胞浆内的外源性DNA的识别和触发机制知之甚少。近年来免疫学基础研究发现：PYHIN蛋白成员--IFI16和AIM2是细胞内的双链DNA感受器，IFI16能够感受胞质和核内dsDNA，发起天然免疫应答，通过不同信号通路最终诱导产生IFN-β参与炎症反应；AIM2可感知转染到胞质中的外源性dsDNA并与其结合，通过其特殊结构域使Caspas-1的活化, 形成炎性复合体，参与炎症反应。不同研究证明，细胞感染病毒后，细胞内的外源性dsDNA会激活AIM2并使之持续表达，成为一个重要的炎症反应物并触发一系列胞内反应，分泌和释放IL-18、IL-1β，进而发挥致炎和致凋亡等多种重要的生物学活性。其中由TLR4介导的信号通路中MyD88 依赖性途径，通过TIR区域向胞内传递信号，激活JNK和NF-κB等因子，引起IL家族蛋白及IFN的释放这一下游信号通路已被多项研究证实。.近年来陆续可见关于PYHIN家族蛋白及细胞内DNA感受器的研究报道，但均局限于免疫学基础研究及肿瘤病因学研究，在感染性疾病中的研究报道则主要集中在细菌感染方面，少量关于HBV与AIM2的研究主要为基础研究，未见PYHIN家族蛋白在HBV感染性疾病中的研究和探讨。HBV是双链DNA病毒，基于在HBV-GN肾组织肾小球固有细胞内中已经明确发现HBV-GN存在及其复制，结合细胞内IFI16和AIM2相关研究取得的上述进展，本研究设定IFI16、AIM2