New insights into the functional diversity of the hepatic antiviral T cell response during hepacivirus infection in vivo

慢性丙型肝炎病毒(HCV)感染等炎症性肝病可进展为肝纤维化和 肝细胞癌(HCC)。肝脏T细胞免疫与肝病密切相关，因为T细胞不是 仅对清除像丙型肝炎病毒这样的嗜肝病毒是必不可少的，但也可能导致肝脏损伤和 导致疾病的发展。然而，不同功能的CD4+和CD8+T细胞亚群的特定作用或 先天T细胞，如自然杀伤T(NKT)细胞，在介导有效的抗病毒免疫反应或 在炎症过程中调节肝脏损伤的机制还不是很清楚。因此，获得了对 肝脏T细胞亚群的功能生物学是发展丙型肝炎疫苗策略和 进行性肝病的免疫治疗选择。 有限的获取人类肝组织的途径和缺乏具有免疫能力的小动物模型阻碍了 肝脏抗病毒免疫机制的研究。然而，我们最近开发了一种免疫能力强的 一种丙型肝炎病毒相关病毒的小鼠模型，挪威大鼠肝炎病毒(NrHV)，它具有显著的病毒学和 免疫学上与人类丙型肝炎病毒感染的相似性。这一进步现在允许深入的机械性 体内抗肝炎病毒免疫的研究。 我们对急性、慢性和继发性NrHV感染期间肝脏淋巴细胞亚群的初步分析显示 显著诱导不同的抗病毒1型T细胞反应和依赖T细胞的病毒清除。然而， 我们还意外地观察到肝脏CD8+T细胞和NKT细胞亚群的极化 促进2型免疫，并可能有助于免疫调节。在这项提案中，我们将在这些基础上 初步数据和阐明不同的肝1型T细胞的功能特性和潜在的串扰 NrHV感染过程中分泌淋巴细胞亚群的2型细胞因子。具体来说，我们将使用高- 三维流式细胞术、体内功能方法和/或转录组分析以1)定义 不同病毒特异性效应器和记忆性CD8+T细胞亚群的功能作用 CD_4~+T细胞对病毒特异性CD8~+T细胞生成和保护性免疫的影响 2型CD8+和NKT细胞亚群的功能，并确定它们对肝损伤、病毒特异性T细胞和 其他肝脏免疫细胞在感染的不同阶段。最后，我们的目标是将我们的主要发现从 给人类丙型肝炎患者建立小鼠模型。 我们的数据将为不同的肝脏1型和2型T细胞的作用和相互作用提供新的生物学见解 和NKT细胞亚群在介导病毒清除、保护性免疫、组织病理或修复过程中的作用 体内嗜肝病毒感染。

Inflammatory liver diseases such as chronic hepatitis C virus (HCV) infection can progress to liver fibrosis and hepatocellular carcinoma (HCC). Hepatic T cell immunity is closely linked to liver diseases since T cells are not only essential for the clearance of hepatotropic viruses like HCV but may also cause liver injury and contribute to disease progression. However, the specific role of functionally distinct CD4+ and CD8+ T cell subsets or innate-like T cells, such as natural killer T (NKT) cells, in mediating an effective antiviral immune response or regulating liver damage during inflammation are not well understood. Thus, gaining new insights into the functional biology of hepatic T cell subsets is a prerequisite for the development of HCV vaccine strategies and immunotherapeutic options for the treatment of progressive liver diseases. Limited access to human liver tissue and the lack of immune-competent small animal models has impeded studies of hepatic antiviral immune mechanisms. However, we have recently developed an immune-competent mouse model of an HCV-related virus, Norway rat hepacivirus (NrHV), which shares significant virological and immunological similarities with HCV infection in humans. This advance now allows for in-depth mechanistic studies of anti-hepaciviral immunity in vivo. Our initial analysis of hepatic lymphocyte subsets during acute, chronic and secondary NrHV infection revealed a significant induction of a diverse antiviral type 1 T cell response and T cell dependent viral clearance. However, we also made the unexpected observation that subsets of hepatic CD8+ T cells and NKT cells are polarized towards type 2 immunity and may contribute to immune-regulation. In this proposal, we will build on these preliminary data and elucidate the functional properties and potential crosstalk of distinct hepatic type 1 T cells and type 2 cytokine secreting lymphocyte subsets during NrHV infection. Specifically, we will use high- dimensional flow cytometry, in vivo functional approaches and/or transcriptome analysis to 1) define the functional role of different virus-specific effector and memory CD8+ T cell subsets, 2) determine the kinetic and impact of CD4+ T cells on the generation of virus-specific CD8+ T cells and protective immunity, 3) delineate the function of type 2 CD8+ and NKT cell subsets and define their impact on liver damage, virus-specific T cells and other hepatic immune cells during different stages of infection. Finally, we aim to translate our main findings from the mouse model to human HCV patients. Our data will provide novel biological insight into the role and interplay of distinct hepatic type 1 and type 2 T cell and NKT cell subsets in mediating viral clearance, protective immunity, tissue pathology or repair during a hepatotropic virus infection in vivo.