γδT细胞在乙肝病毒表面抗原携带状态损伤性肝炎的作用机制研究

HBsAg carriers are susceptible to biochemical-induced liver injury, and immune injury is indispensable in this process. ConA-induced acute liver injury is a perfect model for investigating the mechanism of autoimmune hepatitis. Our recent work reported that γδT cells from HBsAg transgenic mice played a protective role in ConA-induced hepatitis by inhibiting IFN-γ production of CD4+T cells. Pretreatment with IL-23 ameliorated ConA-induced liver injury in HBsAg transgenic mice. The protective role of IL-23 was mediated through IL-17A-producing γδT cells. Even through γδT cells are indispensable for IL-23-mediated protection against ConA-induced HBsAg transgenic mice hepatitis, the mechanism in this process is unclear. We would select ConA-induced HBsAg transgenic mice acute liver injury model and clinical cases to further investigate the role and mechanism of γδT cells in liver injury under HBsAg carrying condition. The main contents included: Gene expression regulation mechanism of endogenous IL-23 inadequate secretion in ConA-induced HBsAg transgenic mice liver injury; Role of endogenous IL-23 in ConA-induced HBsAg transgenic mice liver injury and regulation mechanism of endogenous IL-23 on γδT cells; Role of γδT cells in HBsAg carriers liver injury. This study would provide theoretical basis to the application of γδT cells in the therapy of HBsAg carriers liver injury.

HBsAg携带者的肝脏受外界因素刺激后易发生损伤，其中免疫损伤发挥重要作用。ConA诱导的急性肝损伤是研究自身免疫性肝炎发病机制的理想模型。我们近期报道γδT细胞通过分泌IL-17A抑制CD4+T细胞IFN-γ的分泌，从而在ConA诱导的HBsAg转基因鼠急性肝损伤中发挥保护作用。预先注射外源性IL-23通过促进γδT细胞分泌IL-17A，从而降低HBsAg转基因鼠肝损伤水平。尽管γδT细胞与IL-23介导的保护作用相关，但具体机制仍不明确。本项目拟应用HBsAg转基因鼠急性肝损伤模型和临床病例深入探讨γδT细胞在HBsAg携带状态损伤性肝炎中的作用机制，包括：HBsAg转基因鼠急性肝损伤中内源性IL-23分泌不足的基因表达调控机制；内源性IL-23的作用及其对γδT细胞的调控机制；γδT细胞在HBsAg携带者肝损伤中的作用。本研究将为应用γδT细胞治疗HBsAg携带者肝损伤提供理论依据。

HBsAg携带者的肝脏受外界因素刺激后易发生损伤，其中免疫损伤发挥重要作用。本项目拟应用HBsAg转基因鼠急性肝损伤模型和临床病例深入探讨γδ T细胞在HBsAg携带状态损伤性肝炎中的作用机制。首先探究HBs-Tg小鼠急性肝损伤过程中内源性IL-23分泌不足的基因表达调控机制。结果表明，小鼠肝脏IL-23p19和IL-17A mRNA稳定性下降，mRNA可能存在降解。利用转录组测序技术检测发现HBs-Tg小鼠肝脏IL-23/Th17调控轴相关分子表达水平显著降低，提示HBs-Tg小鼠肝脏IL-23/Th17调控轴功能可能存在受损。内源性IL-23蛋白表达水平调控研究结果表明，γδ T细胞可能是IL-17A和IL-23R的主要细胞来源。此外发现细胞色素P450家族8亚家族B成员-Cyp8b1可能为一种新型乙肝病毒表面抗原携带状态标志物。接下来进行内源性IL-23在HBs-Tg小鼠急性肝损伤中的作用及其对γδ T细胞的调控机制研究。结果表明内源性IL-23的主要细胞来源可能为巨噬细胞和树突状细胞。进一步清除巨噬细胞或树突状细胞可诱导更严重的HBs-Tg小鼠急性肝损伤，而过继转输巨噬细胞或树突状细胞可减轻HBs-Tg小鼠急性肝损伤。将巨噬细胞或树突状细胞与γδ T细胞共培养，可促进γδ T细胞IL-17A分泌，表明巨噬细胞和树突状细胞对γδ T细胞具有一定的调控作用。最后进行γδ T细胞在HBsAg携带者肝损伤中的作用研究。结果表明活动型乙型肝炎病人γδ T细胞功能可能发生功能变化，包括增殖和趋化能力减弱，凋亡水平增强，同时巨噬细胞和树突状细胞功能可能发生变化。本研究将为应用γδ T细胞治疗HBsAg携带者肝损伤提供理论依据。