TLR7通路在慢性乙型肝炎患者干扰素治疗应答中的作用及其机制研究

Interferon α(IFNα)therapy was shown to promote antigen seroconversion to achieve immune control in chronic hepatitis B (CHB) patients. However, how does IFNα regulate host anti-HBV immune function remains largely unknown. Toll like receptor 7 (TLR7) was considered as a dominant innate immune receptor which expressed in B cells and plasmacytoid Dendritic cells(pDC). Our preliminary studies have identified that PBMC stimulated by TLR7 ligand could secret cytokines, including IFNα, to inhibit HBV replication in hepatocytes. Additionally, the expression of TLR7 mRNA and the frequency of B cells in PBMC were increased significantly during peglated-IFNα therapy. Based on these data, we speculated that the induction of TLR7 expression by IFNα might regulate the immune function of B cells and pDC to control HBV infection. To address this hypothesis, we will enroll clinical trial samples and perform in vitro experiments to study the influence of TLR7 expression and activation on B cells and pDC function, and their characteristics during peglated-IFNα therapy. Furthermore, we will confirm the immportant role of TLR7 function in IFNα-mediated clearance of chronic HBV infection and explore the mechanism by HBV mice model in vivo. The findings hopefully would elucidate the relationship between TLR7-mediated immune responses and clinical outcome of IFNα antiviral therapy, and provide experimental and theoretical evidences for clinical application of TLR7 ligands in the therapy of chronic HBV infection.

干扰素α(IFNα)治疗能促使部分慢乙肝患者发生抗原血清学转换以获得免疫控制，但IFNα调节患者免疫功能的机制尚未完全阐明。Toll样受体7(TLR7)是pDC细胞和B细胞表达的重要天然免疫受体，我们前期实验发现TLR7配体可以刺激PBMC分泌IFNα等细胞因子抑制乙肝病毒复制，患者PBMC中TLR7的表达和B细胞的频数在PEG-IFNα治疗过程中显著上调。由此，我们推测，IFNα可能通过诱导TLR7的表达来调节B细胞和pDC细胞的免疫功能，从而控制HBV感染。本项目将利用临床试验队列和体外实验，研究PEG-IFNα治疗过程中TLR7的表达和活化对B细胞和pDC细胞功能的影响及其变化特点。同时在小鼠体内模型中，验证TLR7在IFNα清除慢性乙肝病毒感染中的关键作用及其机制。该研究将揭示TLR7介导的免疫调节作用与IFNα抗病毒治疗应答的关系，为TLR7配体用于临床治疗提供实验和理论依据。

干扰素α(IFNα)治疗能促使部分慢乙肝患者发生抗原血清学转换以获得免疫控制，但IFNα调节患者免疫功能的机制尚未完全阐明。Toll样受体7(TLR7)是pDC细胞和B细胞表达的重要天然免疫受体，其配体可以刺激免疫细胞产生多种抗病毒细胞因子和上调共刺激分子，从而增强抗病毒特异性T细胞和B细胞应答。本课题研究发现，TLR7配体刺激PBMC可通过诱导IFNα的分泌抑制病毒复制，与健康对照来源的PBMC相比，其表达及抗病毒功能在CHB患者中未受到显著影响，并且IFNα的分泌增强，其抑制HBV复制和基因表达的效应更加明显。考虑到TLR7在B细胞内表达较高，在体外实验中，TLR7的活化对B细胞的增殖，活化，细胞因子的分泌均有显著影响。此外，干扰素治疗队列发现PEG-IFN-2a通过上调PBMC上TLR7的表达促使患者获得免疫控制。小鼠体内模型中，TLR7可以协助IFN-α诱导脾内特异性T细胞向肝内迁徙，并增强肝内特异性CD8+T细胞的功能，协同抑制体内HBV复制和基因表达。此外，研究发现TLR7配体对机体免疫有非特异性增强作用，其预处理可以活化HBV特异性T细胞应答，从而促进慢性HBV感染小鼠模型内HBV的清除加快。该研究将揭示TLR7介导的免疫调节作用与IFNα抗病毒治疗应答的关系，为TLR7配体用于临床治疗提供实验和理论依据。