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(丙型肝炎病毒)的美国人中，长期饮酒一直被认为会显著加速肝病的进展。最近的分析表明，长期接触酒精会增加死于丙型肝炎病毒的风险，是单纯病毒感染的8倍以上。尽管它是预测肝硬变和死亡的最有力的独立预测因子之一，但人们对酒精和丙型肝炎病毒致病机制之间相互作用的本质知之甚少。合作研究这一应用的实验室之前的工作表明，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JAK-STAT1途径(限制病毒复制的途径)上的信号。其他研究表明，低甲基化导致丙型肝炎病毒NS3/4蛋白水解酶的激活，这可能通过NS3/4a介导的适配蛋白MAVS的裂解来阻止宿主的先天抗病毒免疫，而STAT1的低甲基化导致其与DNA的结合被抑制。这使得我们可以提出我们的中心假设，即酒精暴露通过甲基化反应的失调而损害感染和未感染丙型肝炎病毒的肝细胞中的干扰素信号，从而加剧丙型肝炎病毒感染。为了验证这一假说，我们提出了三个具体目标，利用体外和体内模型详细研究酒精暴露/甲基化受损和丙型肝炎病毒感染对人类先天性肝细胞免疫的影响。在具体目标1中，我们将研究乙醇在体外对丙型肝炎病毒感染/表达细胞系和人肝细胞中丙型肝炎病毒复制和干扰素信号转导的影响。在具体目标2中，我们将研究乙醇和甲基化受损对嵌合人肝小鼠(SCID-Alb/uPA)丙型肝炎病毒载量和干扰素信号的体内影响。在具体目标3中，我们将评估通过前甲基化试剂甜菜碱纠正乙醇诱导的甲基化缺陷是否恢复了干扰素信号，并改善了接受干扰素2b治疗的感染小鼠的丙型肝炎病毒清除。这些研究的结果将有助于确定酒精损伤的甲基化在干扰素信号转导中的中心作用。 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药物治疗长期饮酒的丙型肝炎病毒感染患者的数据。这些发现最终将通过直接扩展到使用这种新方法的临床试验，最终导致该领域的垂直步骤，其长期目标是减少丙型肝炎病毒感染在长期饮酒患者中导致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.