STAT3在慢性乙型肝炎中活化调节IFNα抗HBV作用及其机制研究

Although interferon-alpha (IFNα) is one of the main drugs for anti-HBV therapy used in the treatment of chronic hepatitis B (CHB), it’s overall response rate only about 30%. Till now, the mechanism of IFNα resistance in CHB patients hasn’t really been elucidated yet. So there might be some undiscovered molecules or mechanisms involved in the development of IFNα resistance. Some published data showed activated Signal transducer and activator of transcription 3 (STAT3) was the very important change in hepatocytes or immune cells during the development of CHB. But it is unknown that whether STAT3 activation is related to poor response to IFNα treatment. Our previous results displayed that expression or phosphorylation of STAT3 was enhanced in HBV-infected hepatocyte. The anti-HBV efficacy of IFNα could be boosted by inhibition of STAT3 phosphorylation. So we propose the hypothesis that STAT3 activation in CHB might have regulatory effects on anti-HBV efficacy of IFNα. In this study, the relationship between STAT3 activation and differences in response to IFNα treatment would be observed comprehensively in CHB patients, cell lines, and STAT3 conditional knockout mouse model. Furthermore, the regulatory mechanism in hepatocyte and immune cells would be explored in depth, and the key factors for regulating anti-HBV efficacy of IFNα would be screened systematically. We expect that this project could provide a new aspect about the mechanism of IFNα resistance and a new target for HBV therapy.

IFNα是慢性乙型肝炎（CHB）抗病毒治疗的主要药物，总应答率仅30%。IFNα应答抵抗机制一直未被阐明而亟需探索新的相关分子或机制。既往数据显示，肝细胞或免疫细胞内STAT3活化可能是CHB发生发展过程中的关键节点，但其是否与IFNα应答不佳相关还未知。我们前期发现，含HBV的肝细胞内STAT3的表达及磷酸化水平均高，抑制STAT3磷酸化水平可增强IFNα抗HBV作用；IFNα应答不良的部分CHB患者在治疗前免疫细胞STAT3高活化。由此推测，CHB中STAT3活化可能参与调节IFNα抗HBV作用。本研究将以CHB患者、细胞模型及STAT3缺陷鼠为研究对象，系统观察STAT3活化与IFNα应答差异的关系，深入探讨肝细胞及免疫细胞内STAT3活化对IFNα抗HBV效应的影响机制，筛选STAT3活化调节IFNα作用的关键分子。以期为揭示IFNα应答抵抗机制提供新思路，为CHB治疗探索新靶点。

慢性乙型肝炎发生发展过程中， STAT3 可以经多种途径被活化而与肝细胞或免疫细胞功能紊乱有关， 但其是否参与 IFNα 应答抵抗机制还未知。本项目检测及分析了慢性乙型肝炎患者或HBV表达小鼠模型中肝组织或外周免疫细胞内STAT3的表达及活化；检测及分析了慢性乙型肝炎患者IFN-α抗病毒治疗过程中STAT3的表达及活化；探讨了炎性细胞因子IL-17对免疫细胞或肝细胞内STAT3的表达及活化的影响，以及对IFN-α信号通路及抗HBV作用的影响。结果显示，慢性HBV感染所致的免疫活化与STAT3相关；STAT3活化与生发中心B细胞相关的负向转录因子BCL-6呈高度正相关，而与一些B细胞发育相关基因呈负相关；IFNα治疗可使外周血STAT3的表达及活化降低。炎性细胞因子IL-17可增强免疫细胞或肝癌细胞株内STAT3的活化IL-17A显著下调Ⅰ型干扰素信号通路相关基因的表达；IL-17A预处理HBV表达的HepG2-HBV1.3细胞，可衰减IFN-α 抗HBV作用，降低IFN-α信号转导分子p-stat1, p-stat2及IRF9的表达，降低IFN-α诱导的抗病毒相关ISG（ISG15, ISG20, MxA）的表达，而增强调节性ISG（SOCS1, SOCS3, USP18）的表达。该研究结果将为改善IFN-α抗HBV治疗疗效提供新思路。