Role of TLR3 Signaling in Control of HCV

描述(申请人提供)：丙型肝炎病毒(丙型肝炎病毒)感染全球约1.3亿人，对人类健康构成重大威胁。丙型肝炎病毒是一种嗜肝的RNA病毒，可在约70%的感染者中引起慢性肝脏炎症，使患者面临肝硬化和肝细胞癌的风险。清除丙型肝炎病毒感染需要发展强大和广泛的CD4和CD8T细胞反应。不幸的是，这些反应经常失败，取而代之的是一种中间的细胞毒性T细胞反应，无法消除感染，但足够强，足以导致肝细胞破坏。针对丙型肝炎病毒的先天免疫反应提供了对抗病毒的第一道防线，对于协调随后的T细胞反应至关重要，但它们如何在肝细胞中发挥作用仍知之甚少。我们最近的数据表明，人类肝细胞含有一个功能性的Toll样受体-3(TLR3)信号通路，该通路可以感知丙型肝炎病毒的感染，并导致促炎细胞因子和趋化因子的产生，而这些细胞因子和趋化因子是募集T细胞到肝脏的中心。然而，TLR3感知病毒复制过程中产生的丙型肝炎病毒双链(DS)RNA并导致NF-kB激活和随后诱导促炎介质的机制尚不清楚。我们推测，这些在丙型肝炎病毒与肝细胞相互作用中的分子事件在宿主对丙型肝炎病毒的免疫反应中是至关重要的。因此，更好地了解这些分子事件对于增进我们对宿主对丙型肝炎的免疫应答和肝细胞中TLR3信号机制的了解至关重要，并为开发新的丙型肝炎免疫疗法奠定基础。目的1将确定病毒复制过程中产生的丙型肝炎病毒dsRNAs被TLR3在内体/溶酶体间感知的机制。我们将描述自噬在依赖TLR3的宿主对丙型肝炎病毒感染的反应中的作用，并鉴定和鉴定在丙型肝炎病毒感染过程中被招募到内溶酶体以促进TLR3信号转导的细胞蛋白。目的2研究丙型肝炎病毒TLR3途径下游激活核因子-kB的信号机制，以及随后促炎症细胞因子和趋化因子的诱导。我们还将确定选定的先天免疫信号分子和促炎介质在丙型肝炎患者特定队列的诊断性肝活检样本中的表达，并确定它们与肝脏炎症的可能关系。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) infects approximately 130 million people worldwide and poses a major threat to human health. HCV is a hepatotropic RNA virus that causes chronic hepatic inflammation in ~70% of infected individuals, putting patients at risk for cirrhosis and hepatocellular carcinoma. Clearance of HCV infection requires the development of vigorous and broad CD4 and CD8 T cell responses. Unfortunately, these responses often fail and are substituted with an intermediate cytotoxic T cell response unable to eliminate the infection but strong enough to cause hepatocyte destruction. The innate immune responses to HCV provide the first line of defense against the virus and are pivotal for orchestrating subsequent T cell responses, but how they operate in hepatocytes remains poorly understood. Our recent data suggest that human hepatocytes contain a functional Toll-like receptor-3 (TLR3) signaling pathway that senses HCV infection and leads to production of proinflammatory cytokines and chemokines which are central to recruiting T cells to the liver. However, the mechanisms by which TLR3 senses HCV double-stranded (ds) RNAs generated during viral replication and results in NF-kB activation and subsequent induction of proinflammatory mediators are unclear. We hypothesize that these molecular events in HCV-hepatocyte interactions are crucial in host immune responses to HCV. Therefore a better understanding of these molecular events is crucial for advancing our knowledge on host immune responses to HCV and the mechanisms of TLR3 signaling in hepatocytes, and lays the foundation for developing novel immunotherapies for hepatitis C. The work proposed involves two specific aims. Aim 1 will determine the mechanism by which HCV dsRNAs generated during viral replication are sensed by TLR3 in endosome/lysosome compartments. We will delineate the role of autophagy in TLR3- dependent host response to HCV infection, and identify and characterize cellular proteins that are recruited to endolysosomes to facilitate TLR3 signaling during HCV infection. Aim 2 will characterize the signaling mechanisms downstream of the TLR3 pathway by which HCV activates NF-kB and subsequent induction of proinflammatory cytokines and chemokines. We will also determine the expression of selected innate immune signaling molecules and proinflammatory mediators in diagnostic liver biopsy specimens from a specific cohort of hepatitis C patients and define their possible relationship to hepatic inflammation.