TP53BP2通过抑制SOCS2正向调节慢乙肝患者的干扰素应答

血清表面抗原（HBsAg）阴转是慢性乙肝患者抗病毒治疗的理想终点。目前对宿主遗传因素在慢性乙肝临床治愈中的作用缺乏了解。实验室前期队列遗传关联分析发现，肿瘤蛋白P53结合蛋白2（TP53BP2）在肝组织特异性高表达利于患者HBsAg阴转。本课题将探讨TP53BP2对慢性乙肝患者干扰素（IFN）治疗应答转归的影响。在利用不同数据库明确TP53BP2高表达与肝组织内ISG15、MxA以及OAS2等IFN刺激基因呈正相关的基础上，通过HBV复制、感染细胞模型和水压动力注射小鼠模型验证TP53BP2的抗病毒作用，并在机制上探讨其通过对细胞因子信号抑制因子2（SOCS2）的表达抑制，一定程度上解除IFN抗病毒通路的负反馈调节，增强其抗病毒作用。本研究将首次揭示TP53BP2与SOCS家族蛋白在IFN抗感染免疫中的交互作用，为以“临床治愈”为目标的新药研发提供线索，为慢性乙肝个体化治疗提供依据。

HBsAg seroclearance with or without anti-HBs appearance has been considered as an ideal treatment end of chronic hepatitis B (CHB). In addition to viral characteristics, the genetic background of patients should also play an important role in the eventual clearance of HBV under antiviral therapy. In our previous cohort study, CHB patients treated with Peg-IFN based regimen were genotyped using whole-genome sequencing and single-nucleotide polymorphisms (SNPs) associated with HBsAg loss were screened by genome-wide association analysis. TP53BP2, a TP53 binding protein, has been identified associated with the occurrence of HBsAg seroclearance of CHB patients after received antiviral therapy. Further expression quantitative trait loci (eQTL) analysis revealed the relatively higher expression of TP53BP2 specific in the liver in favor of the functional cure of CHB. In this proposal, we aimed to validate the result of previous GWAS study and explore further the underlying mechanism. .Preliminary data derived from Human Transcriptome Array database showed that after knockdown of TP53BP2 gene in hepatocytes, the innate immunity-related pathway was among the top pathways which functions of differentially expressed genes enriched. Results of in vitro cell experiments showed that, after knockdown of TP53BP2 gene by siRNAs, the mRNA levels of interferon-stimulated genes like ISG15, OAS2, and MX1 were significantly down-regulated, as compared to control group, either in HepAD38 or in Huh7 cells. In contrast, the mRNA level of suppressor of cytokine signaling 2 (SOCS2), the negative regulatory gene of the IFN/JAK/STAT pathway, was significantly up-regulated (P<0.05). Based on this preliminary data, we proposed that higher expression of TP53BP2 in the liver could enhance interferon’s antiviral activity via downregulation of SOCS2 in patients with chronic hepatitis B. Next, we will explore the negative regulation of TP53BP on the transcription of SOCS2 gene promoter mechanistically. To do so, a series of experiments were designed. Besides, experiments including HBV replication and/or infection cell models will be used to validate if TP53BP2 enhances IFN-a antiviral activity via inhibiting SOCS2 expression at the transcriptional level. Moreover, Socs2-/-, Tp53bp2+/- and Tp53bp2/Socs2 double-knockout mice mouse will be used to confirm the results obtained from the in vitro cell model-based experiments. Eventually, the above postulation should be validated by the use of mouse model, via hydrodynamic tail vein injection of 1.2×HBV DNA construct. The findings in this study will enhance our understanding of the role of innate immunity in the control of chronic HBV infection. Since this study is started from a GWAS study based on the SNPs analysis, the discovery made from this proposed study will potentially benefit the CHB patients through personalized antiviral therapy.