天然免疫相关分子TRIM25与HBV之间相互抑制作用的机制研究

Hepatitis B virus infection is a worldwide health problem. Interferon is one of the main drugs for the treatment of viral hepatitis, but the limited efficacy limits its clinical application. Our preliminary studies showed the innate immune associated molecules: TRIM25 could be up-regulated through STAT1/3 after IFN stimulation, so as to further promote type I interferon to inhibit the replication of HBV.However, the expression of TRIM25 in PBMC was significantly decreased in HBV patients. We also found that HBV can inhibit TRIM25 that promote the production of interferon in turn, which indicated hepatitis B virus could inhibit TRIM25 expression through some special mechanisms, so as to achieve the purpose of immune escape, this might be one of the reasons for the interferon resistance. Then we found that: The promoter region of TRIM25 has the binding site of STAT1/3,TRIM25 can interact with HBx and degrade HBx but the specific mechanism has not been clarified. This project will further elucidate the molecular mechanism involved in the mutual inhibition between TRIM25 and HBV by gene engineering technology,WB,qPCR,CO-immunoprecipitation method etc. and clarify the interaction between TRIM25 and HBx and its specific effect on HBV replication. The present study will provide an insight into the mechanism of pathogen host interactions , "crossing" immune tolerance limit, and provide new ideas and therapeutic targets for more effective treatment of chronic hepatitis B.

乙型肝炎病毒感染是世界性的卫生难题，人体感染HBV后多无法自发清除，造成感染慢性化进展。干扰素是治疗乙型病毒性肝炎的主要药物之一，但有限的疗效限制了其临床应用。申请人前期研究发现：干扰素可以通过STAT1/3诱导TRIM25的表达从而起到抗HBV的作用，然而临床上HBV病人PBMC中TRIM25的表达明显降低，细胞实验证实HBV可以抑制TRIM25的表达从而实现免疫逃逸。我们进一步研究发现：TRIM25的启动子区有STAT1/3的结合位点，TRIM25可以与HBx相互作用并使HBx降解，但具体机制尚不明确。本项目拟通过基因工程、WB、qPCR、Co-IP等方法，进一步阐明TRIM25与HBV之间相互抑制作用机制，为深入理解干扰素抗HBV作用机制及HBV诱导宿主免疫耐受机制提供理论基础，为开发新型抗HBV治疗药物提供作用靶点。

HBV入侵人体后可引起慢性乙型病毒性肝炎，最终进展至肝硬化、肝癌。人体感染HBV后多无法自发清除，造成感染慢性化进展。干扰素是治疗乙型病毒性肝炎的主要药物之一，但有限的疗效限制了其临床应用。申请人前期研究发现：干扰素可以通过STAT1/3诱导TRIM25的表达从而起到抗HBV的作用，但具体机制尚不明确。在本项目基金支持下课题组进行了深入研究，我们发现TRIM25作为E3泛素连接酶通过蛋白酶体途径促进HBx降解；TRIM25通过促进HBx蛋白K90位点的泛素化促进HBx降解；除了TRIM25的Ring结构域，SPRY结构域在这个过程中也是不可或缺的；TRIM25可以通过与RIG-I相互作用增强对HBV pgRNA的识别，这可能进一步促进下游干扰素通路激活。进一步阐明TRIM25与HBV之间相互抑制作用机制，为深入理解干扰素抗HBV作用机制及HBV诱导宿主免疫耐受机制提供理论基础，为开发新型抗HBV治疗药物提供作用靶点。