天然免疫受体AIM2在乙型肝炎中的作用研究

It is reported that the AIM2 (absent in melanoma 2) protein can promote host defenses against invading viruses and pathogenic bacteria through corresponding adapter molecules leading to the initiation of innate immune responses. Whether AIM2 and its inflammasome are involved in the immune clearance of hepatitis B virus (HBV) in the host, is unclear yet. Our previous study indicated that there is a higher expression of AIM2, IL-1β, and IL-18 in acute hepatitis B (AHB), and a lower expression of that in chronic Hepatitis B (CHB). This suggests that there be a higher immune status in AHB, and a lower immune response in CHB.AIM2mRNA expression was positively correlated with IL-1β and IL-18, and negatively correlated with HBV DNA loads in AHB patients and CHB patients with immune clearance, which suggests that AIM2 expression should be correlated with the immune clearance of HBV in the host. Our results suggest that the down-regulation of AIM2 should be associated with chronic HBV infection.We will establish cell model of HBV infection by using PBMCs of healthy people,to further confirm these conclusions from the perspective of signal transduction pathway of AIM2 and its inflammasome by using RNAi and IP or CHIP experiments.These results would help us clarify precise role of AIM2 in the hepatitis B,and provide the novel insights into the mechanism of hepatitis B.

研究表明天然免疫受体黑色素瘤缺失因子2（AIM2）及其炎症复合体与机体抗病毒免疫密切相关。AIM2及其炎症复合体是否参与了机体清除乙肝病毒的免疫反应尚不清楚。我们初步研究发现,急性乙肝患者AIM2、IL-1β和IL-18的表达显著高于慢性乙肝。急性乙肝和慢性乙肝免疫清除期(急性活动期)AIM2mRNA表达与HBVDNA之间存在显著的负相关,与IL-1β、IL-18之间存在显著的正相关,提示AIM2表达水平与机体免疫清除HBV有关,AIM2低水平表达可能与乙肝慢性化相关。本项目拟分离健康人外周血单个核细胞并暴露于HBV环境培养,用RNA干扰和免疫共沉淀等实验,从AIM2及其炎症复合体的信号转导角度进一步确证AIM2表达水平与机体免疫清除HBV的关联及AIM2低水平表达与HBV感染慢性化的关系。该项研究将阐明机体天然免疫受体AIM2在乙肝中的作用,也为慢性乙肝发生机制研究提供新的思路。

我们前期研究发现,急性乙肝患者AIM2、IL-1β和IL-18的表达显著高于慢性乙肝。急性乙肝和慢性乙肝免疫清除期(急性活动期)AIM2mRNA表达与HBVDNA之间存在显著的负相关, 与IL-1β、IL-18之间存在显著的正相关。本项目分离健康人外周血单个核细胞并暴露于HBV环境培养,进行免疫共沉淀等实验，实验结果不理想；而肝脏活检免疫组化实验提示，急性乙肝与慢性乙肝免疫清除期肝脏细胞内AIM2较免疫耐受期有增高趋势。急性乙肝肝细胞核内，也存在AIM2不典型表达。提示AIM2表达水平与机体免疫清除HBV有关,AIM2低水平表达可能与乙肝慢性化相关。另外，初步研究发现慢性乙肝免疫耐受期mIL-1β和mIL-18水平明显低于急性乙肝和慢性乙肝免疫清除期，推测可能与免疫耐受期高水平的HBeAg以及HBsAg有关。本研究选取慢性乙肝免疫耐受期患者外周血50例以及肝脏穿刺30例研究样本，采用活细胞内蛋白质相互作用实验，即NanoBRET，检测慢性乙肝免疫耐受期患者PBMCs与肝细胞中HBeAg以及HBsAg作用的靶蛋白。结果表明其与某些接头蛋白发生了相互作用，提示HBeAg与HBsAg可能通过干预天然免疫受体复合体的形成，从而影响下游IL-1β和IL-18的成熟，下调了机体免疫强度。该研究为乙肝慢性化机制研究提供了新思路。