原发性胆汁性肝硬化中cGAS-STING通路对单核细胞I型IFN系统的调控及其发病机制研究

Primary biliary cirrhosis (PBC) is an autoimmune disease characterized by bile duct progressive non-suppurative inflammation. The abnormal activation of monocytes has been proposed to account for the loss of self-tolerance. Our studies found that cGAS and STING expression significantly increased in monocytes from PBC patients; cGAS expression increased along with the course of the disease in PBC mice models; inhibition of cGAS expression could reduce the levels of LPS-induced STING and typeⅠinterferon. This project intends to explore the following key issues: 1. the mechanism of cGAS pathway regulating on typeⅠinterferon activation in PBC patients;.2. the regulation mechanism of DNA methylation and important transcription factors on cGAS expression in monocytes from PBC patients;3.using mice models to explore the regulating function of cGAS on PBC disease course. These investigations would clarify the regulation mechanism of cGAS on type I interferon in monocytes from PBC patients, providing a theoretical basis to explore novel ways to immune intervention therapy.

原发性胆汁性肝硬化（Primary Biliary Cirrhosis，PBC）是以肝内小胆管破坏为主要病理特征的常见自身免疫性肝病，患者体内异常激活的单核细胞是免疫耐受缺失的重要因素。本课题组前期研究表明，PBC患者单核细胞中cGAS和STING表达显著增高，且与病理分期相关；抑制cGAS表达，可导致单核细胞中LPS刺激的STING和Ⅰ型IFNs水平下降；在PBC小鼠模型中单核细胞cGAS水平随病程增高。本项目拟解决以下关键问题：1、cGAS信号通路对PBC患者Ⅰ型干扰素系统的调节机制；2、甲基化或重要转录因子对PBC患者cGAS表达的调控机制；3、cGAS干预对PBC小鼠模型病程的调节作用。通过本研究，将有助于阐明PBC中cGAS信号通路对I型IFN系统免疫应答的调控机制，为探讨免疫治疗新途径提供理论依据。

在本研究中，我们主要探讨了cGAS和STING在原发性胆汁性肝硬化(PBC)发病机制中的作用。我们首先比较了来自健康个体个PBC患者单核细胞被LPS刺激后释放炎症因子IL-1β和和IFN-β的能力，发现PBC患者的单核细胞对LPS刺激呈现出高反应性。使用siRNA一直cGAS和STING的表达后，PBC患者单核细胞释放IL-1β和和IFN-β明显降低。将cAGS和STING的siRNA注射入poly: IC诱导的PBC小鼠模型，发现小鼠的病情明显缓解。使用DNA甲基化转移酶抑制5-aza-DC处理PBC患者单核细胞，再用LPS刺激后，发现单核细胞释放IL-1β和和IFN-β的能力增强。此外，我们还研究了IL-35在PBC发病机制中的作用，发现PBC患者血清IL-35水平明显降低，且与临床特征相关。提示其参与了PBC的发病机制。研究提示cGAS-STING信号通路在PBC发病机制中发挥重要作用，是PBC潜在的治疗靶点。