Immunopathogenesis of hepatitis B virus and hepatitis C virus infection

乙型肝炎病毒和丙型肝炎病毒感染的免疫发病机制

• 批准号: 134144310
• 负责人: Professor Dr. Robert Thimme
• 金额: --
• 依托单位: Klinik für Innere Medizin II - Gastroenterologie, Hepatologie, Endokrinologie und Infektiologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2009
• 资助国家: 德国
• 起止时间: 2008-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/134144310?language=en
• 关键词: Immunopathogenesis; hepatitis; virus; infection

Virus-specific CD8+ T cell responses play a major role in outcome and pathogenesis of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. By using immunological cell culture models provided by the FOR, our group has yielded several novel insights into success and failure of these virus-specific CD8+ T cell responses in controlling infection. During the second funding period we will address two main aspects. The first one deals with the relative contribution of HBV specific effector functions to antiviral efficacy. The relative contribution of cytolytic versus non-cytolytic effector mechanisms in HBV control is poorly defined. Indeed, studies in HBV-transgenic mice have indicated a dominant role of non-cytolytic effector functions while studies in chimpanzees have also shown an important function of cytolytic effector molecules. In this subproject, we will analyze the ex vivo effector function of HBV-specific CD8+ T cells from patients with acute and chronic HBV infection by using a novel human immunological HBV cell culture model. This newly established model is based on an HBV producing, HLA-A2 expressing human hepatoma cell line (HepG2.117) that endogenously processes HBV antigen. In own preliminary work, we could show that CD8+ T cell-mediated antiviral efficacy is primarily mediated by perforin-depending cytolytic effector functions. With this model, we will also analyze different approaches to restore HBV-specific CD8+ T cell function, e.g. by addition of cytokines and blockade of inhibitory receptors. In addition to our established cell culture system, we will also use primary human hepatocytes to further define the important interactions between immune cells and HBV-infected hepatocytes and their impact on viral control. The second subproject deals with the restoration of HCV-specific CD8+ T cell dysfunction. By using HLA-A2 replicon cells, we could show that HCV-specific CD8+ T cells inhibit replication by non-cytolytic (IFNγ-mediated) and cytolytic effector functions and that HCV specific CD8+ T cells obtained from chronically HCV-infected patients show an impaired antiviral efficacy that can not be restored by cytokines. By using the infectious cell culture model, we will now analyze whether HCV infection influences HCV-specific CD8+ T cell function and antiviral efficacy and to what degree innate immune responses (e.g. IFNα) impact on CD8+ T cell function, e.g. by reducing antigen load beyond the level of T cell recognition. Since it is also not known whether the dysfunction of HCVspecific CD8+ T cells is directly linked to ongoing viral replication and whether inhibition of viral replication would thus lead to restoration of HCV-specific T cell functions, we will address this important question in a well defined patient cohort of chronically HCV infected patients undergoing antiviral IFN-free therapy. Overall, these comprehensive analyses should provide important new insights into HBV and HCV immunobiology.

病毒特异性CD8+ T细胞反应在乙型肝炎病毒（HBV）和丙型肝炎病毒（HCV）感染的结局和发病机制中起重要作用。通过使用由FOR提供的免疫细胞培养模型，我们的团队已经对这些病毒特异性CD8+ T细胞反应在控制感染方面的成功和失败产生了一些新的见解。在第二个资助期，我们将处理两个主要方面。第一个是HBV特异性效应功能对抗病毒疗效的相对贡献。细胞溶解与非细胞溶解效应机制在HBV控制中的相对作用尚不明确。事实上，对hbv转基因小鼠的研究表明非细胞溶解效应分子起主导作用，而对黑猩猩的研究也表明细胞溶解效应分子起重要作用。在这个子项目中，我们将利用一种新的人类免疫HBV细胞培养模型，分析急性和慢性HBV感染患者的HBV特异性CD8+ T细胞的体外效应功能。这个新建立的模型是基于一种内源性加工HBV抗原的产生HBV、表达HLA-A2的人肝癌细胞系（HepG2.117）。在自己的初步工作中，我们可以证明CD8+ T细胞介导的抗病毒功效主要是由穿孔依赖的细胞溶解效应物功能介导的。通过这个模型，我们还将分析恢复hbv特异性CD8+ T细胞功能的不同方法，例如通过添加细胞因子和阻断抑制受体。除了我们建立的细胞培养系统外，我们还将使用原代人肝细胞进一步确定免疫细胞与hbv感染肝细胞之间的重要相互作用及其对病毒控制的影响。第二个子项目涉及hcv特异性CD8+ T细胞功能障碍的恢复。通过使用HLA-A2复制子细胞，我们可以证明HCV特异性CD8+ T细胞通过非细胞溶解（ifn γ-介导）和细胞溶解效应抑制复制，并且从慢性HCV感染患者获得的HCV特异性CD8+ T细胞显示出无法通过细胞因子恢复的抗病毒功效受损。通过使用感染性细胞培养模型，我们现在将分析HCV感染是否影响HCV特异性CD8+ T细胞功能和抗病毒功效，以及先天免疫反应（如IFNα）对CD8+ T细胞功能的影响程度，例如通过降低抗原负荷超过T细胞识别水平。由于尚不清楚HCV特异性CD8+ T细胞的功能障碍是否与正在进行的病毒复制直接相关，以及抑制病毒复制是否会因此导致HCV特异性T细胞功能的恢复，我们将在接受抗病毒IFN-free治疗的慢性HCV感染患者的明确患者队列中解决这个重要问题。总的来说，这些综合分析应该为HBV和HCV免疫生物学提供重要的新见解。