Ethanol-Induced Hypomethylation Accelerates Hepatitis C Progression

描述（由申请人提供）： 摘要：在大约400万感染丙型肝炎病毒（HCV）的美国人中，长期饮酒长期以来一直被认为会大大加速肝脏疾病的进展。最近的分析表明，长期酒精暴露会使HCV死亡的风险增加8倍以上。尽管酒精是肝硬化和死亡的最强独立预测因子之一，但酒精与HCV发病机制之间相互作用的性质知之甚少。合作研究这一应用的实验室先前的工作表明，乙醇暴露会损害肝细胞中的蛋白质甲基化，并减少干扰素诱导的信号沿着JAK-STAT 1通路（限制病毒复制的通路）。其他人已经证明，低甲基化导致HCV NS 3/4蛋白酶的激活，这可能通过NS 3/4a介导的衔接蛋白MAVS的切割而潜在地阻断宿主先天性抗病毒免疫，并且STAT 1的低甲基化导致其与DNA的附着受到抑制。这使得我们的核心假设，即乙醇暴露加剧了HCV感染，通过损害干扰素信号在HCV感染和未感染的肝细胞通过甲基化反应失调。为了验证这一假设，我们提出了三个具体目标，利用体外和体内模型详细研究乙醇暴露/受损甲基化和HCV感染对人类先天性肝细胞免疫的影响。在具体目标1中，我们将研究乙醇对HCV感染/表达细胞系和人肝细胞中HCV复制和干扰素信号传导的体外影响。在具体目标2中，我们将研究乙醇和受损甲基化对嵌合人肝小鼠（scid-Alb/uPA）中HCV载量和干扰素信号传导的体内影响。在具体目标3中，我们将评估前甲基化剂甜菜碱对乙醇诱导的甲基化缺陷的校正是否恢复干扰素信号传导并改善用IFN 2b治疗的感染小鼠中的HCV清除。这些研究的结果将有助于确定乙醇损伤的甲基化在IFN信号传导中的中心作用 用于抑制宿主防御、病毒复制和致病。此外，我们还将获得支持使用促甲基化剂治疗慢性饮酒的HCV感染患者的数据。这些发现将最终导致该领域的垂直步骤，通过直接扩展到临床试验，使用这种新的方法，长期果阿是降低慢性酒精使用患者中HCV感染引起的过度发病率和死亡率。

DESCRIPTION (provided by applicant): Abstract: Amongst the roughly 4 million Americans infected with the Hepatitis C Virus (HCV), chronic alcohol use has long been known to dramatically accelerate the progression of liver disease. Recent analysis has shown that long-term alcohol exposure increases the risk of death from HCV more than 8-fold over viral infection alone. Despite its importance as one of the strongest independent predictors of both cirrhosis and death, very little is known about the nature of the interaction between alcohol and HCV pathogenesis. Previous work from the laboratories collaborating on this application has shown that ethanol exposure impairs protein methylation in liver cells and reduces IFN-induced signaling along the JAK-STAT1 pathway (pathway that limits viral replication). Others have demonstrated that hypomethylation leads to activation of HCV NS3/4 protease, which may potentially block host innate antiviral immunity through NS3/4a-mediated cleavage of the adaptor protein, MAVS and that hypomethylation of STAT1 causes suppression of its attachment to DNA. This allows formulating our central hypothesis that ethanol exposure exacerbates HCV infection by impairing interferon signaling in HCV-infected and uninfected hepatocytes via dysregulation of methylation reactions. To test the hypothesis, we propose three Specific Aims to perform detailed examination of the effects of ethanol exposure/impaired methylation and HCV-infection on human innate hepatocyte immunity utilizing both in vitro and in vivo models. In Specific Aim 1, we will investigate the in vitro effects of ethanol on HCV replication and interferon signaling in HCV-infected/ expressing cell lines and human hepatocytes. In Specific Aim 2, we will study the in vivo effects of ethanol and impaired methylation on HCV load and interferon signaling in mice (scid-Alb/uPA) with chimeric human livers. In Specific Aim 3 we will assess whether the correction of ethanol- induced methylation defects by the pro-methylating agent, betaine, restores interferon signaling and improves HCV clearance in infected mice treated with IFN¿2b. The results of these studies will aid in the determination of the central role for ethanol-impaired methylation in IFN signaling for suppression of host defense, viral replication and pathogenesis. In addition, we will also obtain data in support of the use of pro-methylation agents in the treatment of HCV-infected patients with chronic alcohol use. These findings would ultimately lead to a vertical step in the field through direct extension to a clinical trial using this novel approach with the long-term goa of reducing the excessive morbidity and mortality that HCV infection causes in patients with chronic alcohol use.