HCV 感染中的固有和适应性免疫反应。

Innate and adaptive immune responses in HCV infections.

机构信息

Division of Gastroenterology and Hepatology, University Hospital Basel, Petersgraben 4, 4031 Basel, Switzerland; Department of Biomedicine, University of Basel, Hebelstrasse 20, 4031 Basel, Switzerland.

Department of Medicine, Clinic for Gastroenterology, Hepatology, Endocrinology, Infectious Diseases, University Hospital Freiburg, Freiburg, Germany.

出版信息

J Hepatol. 2014 Nov;61(1 Suppl):S14-25. doi: 10.1016/j.jhep.2014.06.035. Epub 2014 Nov 3.

Abstract

Hepatitis C virus has been identified a quarter of a decade ago as a leading cause of chronic viral hepatitis that can lead to cirrhosis and hepatocellular carcinoma. Only a minority of patients can clear the virus spontaneously during acute infection. Elimination of HCV during acute infection correlates with a rapid induction of innate, especially interferon (IFN) induced genes, and a delayed induction of adaptive immune responses. However, the majority of patients is unable to clear the virus and develops viral persistence in face of an ongoing innate and adaptive immune response. The virus has developed several strategies to escape these immune responses. For example, to escape innate immunity, the HCV NS3/4A protease can efficiently cleave and inactivate two important signalling molecules in the sensory pathways that react to HCV pathogen-associated molecular patterns (PAMPs) to induce IFNs, i.e., the mitochondrial anti-viral signalling protein (MAVS) and the Toll-IL-1 receptor-domain-containing adaptor-inducing IFN-β (TRIF). Despite these escape mechanisms, IFN-stimulated genes (ISGs) are induced in a large proportion of patients with chronic infection. Of note, chronically HCV infected patients with constitutive IFN-stimulated gene (ISG) expression have a poor response to treatment with pegylated IFN-α (PegIFN-α) and ribavirin. The mechanisms that protect HCV from IFN-mediated innate immune reactions are not entirely understood, but might involve blockade of ISG protein translation at the ribosome, localization of viral replication to cell compartments that are not accessible to anti-viral IFN-stimulated effector systems, or direct antagonism of effector systems by viral proteins. Escape from adaptive immune responses can be achieved by emergence of viral escape mutations that avoid recognition by antibodies and T cells. In addition, chronic infection is characterized by the presence of functionally and phenotypically altered NK and T cell responses that are unable to clear the virus but most likely contribute to the ongoing liver disease. In this review, we will summarize current knowledge about the role of innate and adaptive immune responses in determining the outcome of HCV infection.

摘要

丙型肝炎病毒在四分之一世纪前被确定为导致慢性病毒性肝炎的主要原因,这种肝炎可导致肝硬化和肝细胞癌。只有少数患者在急性感染期间能够自发清除病毒。急性感染期间 HCV 的清除与先天免疫,特别是干扰素 (IFN) 诱导基因的快速诱导以及适应性免疫反应的延迟诱导相关。然而,大多数患者无法清除病毒,并在持续的先天和适应性免疫反应下发展为病毒持续存在。病毒已经开发了几种策略来逃避这些免疫反应。例如,为了逃避先天免疫,HCV NS3/4A 蛋白酶可以有效地切割和失活两条重要的信号通路中的两个信号分子,这些信号分子对 HCV 病原体相关分子模式 (PAMPs) 作出反应,从而诱导 IFNs,即线粒体抗病毒信号蛋白 (MAVS) 和 Toll-IL-1 受体结构域包含衔接诱导 IFN-β (TRIF)。尽管存在这些逃逸机制,但慢性感染患者中有很大一部分会诱导 IFN 刺激基因 (ISGs)。值得注意的是,慢性 HCV 感染患者中存在组成型 IFN 刺激基因 (ISG) 表达,对聚乙二醇化 IFN-α (PegIFN-α) 和利巴韦林的治疗反应不佳。保护 HCV 免受 IFN 介导的先天免疫反应的机制尚未完全了解,但可能涉及在核糖体上阻断 ISG 蛋白翻译、将病毒复制定位到无法被抗病毒 IFN 刺激效应系统访问的细胞隔室,或病毒蛋白直接拮抗效应系统。通过出现逃避抗体和 T 细胞识别的病毒逃逸突变,可以实现对适应性免疫反应的逃避。此外,慢性感染的特征是 NK 和 T 细胞反应的功能和表型改变,这些反应无法清除病毒,但很可能导致持续的肝病。在这篇综述中,我们将总结先天和适应性免疫反应在决定 HCV 感染结局中的作用的最新知识。

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