Heme Oxygenase-1 Inhibition of Hepatitis C Replication

描述(由申请人提供)： 丙型肝炎病毒是一个全球性的健康问题，可导致慢性肝炎、肝硬变和肝细胞癌。近50%的感染患者对干扰素治疗没有反应，开发其他治疗方式至关重要。肝损伤可能是由病毒感染过程中产生的超氧化物和过氧化氢等氧化剂引起的，并损害肝细胞和周围细胞。肝细胞通常会上调氧化防御酶，以维持氧化还原平衡，防止肝脏损伤。血红素加氧酶-1(HO-1)是一种氧化防御酶，是在氧化应激条件下诱导的。这种酶的反应产物胆绿素、一氧化碳和铁在细胞中起着重要的作用，以维持细胞止血和防止损伤。我们实验室过去的工作表明，丙型肝炎病毒可以转录调控HO-1的表达。最近，我们报道了HO-1的过表达或用氯化血红素诱导可以抑制病毒复制，同时保护丙型肝炎病毒复制子细胞免受氧化损伤。因此，我们的研究结果有力地表明，用氯化血红素等药物诱导HO-1可能是辅助抗病毒治疗治疗丙型肝炎病毒感染和/或预防慢性肝病的一条新的令人兴奋的途径。这一应用的主要目的是描述HO-1诱导及其酶产物抑制丙型肝炎病毒复制和减少氧化应激的细胞机制。这一应用的中心假设是，HO-1是一种重要的肝细胞防御酶，其反应产物可以减弱丙型肝炎病毒的复制，并保护其免受病毒引起的氧化损伤。利用已建立的丙型肝炎病毒非结构复制子和全长复制子的细胞系以及支持丙型肝炎病毒体外生命周期的JFH6细胞系，我们将验证中心假设，并通过三个特定目标的实验来实现主要目标：1)我们将研究HO反应产物铁和胆绿素/胆红素在丙型肝炎病毒感染的肝细胞中作为HO-1抗病毒活性的介体的作用。2)我们将研究血红素加氧酶反应产物、胆绿素/胆红素、一氧化碳和铁在减轻和/或调节病毒引起的氧化应激中的作用；3)我们将研究在基础条件下和在应激反应中，丙型肝炎病毒作为HO-1表达的调节因子的作用。由于HO-1是在氧化应激下被诱导的，因此阐明病毒必须如何调节HO-1的表达是很重要的。这项工作将扩大我们对慢性丙型肝炎病毒感染期间发生的病毒复制和肝脏损伤的了解。这也将为开发一类新的抗病毒药物奠定基础，这些药物可能成为慢性丙型肝炎病毒感染的辅助治疗。对退伍军人医疗保健的潜在影响：退伍军人慢性丙型肝炎病毒感染的发病率更高，发病率和死亡率比一般人群更高。这些研究的结果极有可能对退伍军人的护理产生积极影响，带来新的治疗模式和管理选择。 公共卫生相关性： 丙型肝炎病毒是一个全球性的健康问题。这项工作将研究病毒如何导致人类肝病，以及人类肝脏如何对病毒做出反应。这项工作的重要性在于，它将直接适用于人类感染丙型肝炎病毒的治疗。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) is a global health problem, causing chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Nearly 50% of infected patients do not respond to interferon therapy and it is crucial to develop additional therapeutic modalities. Hepatic injury is likely initiated by oxidants such as superoxide and peroxide that arise during viral infection and damage hepatocytes and surrounding cells. Hepatocytes normally up- regulate oxidative defense enzymes to maintain redox balance and prevent liver injury. Heme oxygenase-1 (HO-1) is an oxidative defense enzyme that is induced in response to oxidative stress. The enzyme's reaction products, biliverdin, carbon monoxide, and iron serve important functions in the cell to maintain cellular hemostasis and prevent injury. Past work from our laboratory has shown that HCV can transcriptionally regulate expression of HO-1. More recently, we reported that HO-1 overexpression or induction with hemin can attenuate viral replication and at the same time protect against oxidative injury in HCV replicon cells. Consequently, our findings strongly suggest that induction of HO-1 with drugs such as hemin may be a new exciting avenue for adjunctive antiviral therapy to treat HCV infection and/or prevent chronic liver disease. The major objective of this application is to characterize the cellular mechanisms whereby HO-1 induction and its enzymatic products inhibit HCV replication and reduce oxidative stress. The central hypothesis of this application is that HO-1 is an important hepatocellular defense enzyme whose reaction products attenuate HCV replication as well as protect against oxidative injury caused by the virus. Using established cell lines of HCV nonstructural and full length replicons as well as JFH6 line that supports the cellular life cycle of HCV in vitro, we will test the central hypothesis and accomplish the major objectives by undertaking experiments of three specific objectives: 1) We will investigate the role of HO reaction products iron and biliverdin/bilirubin as mediators of HO-1 antiviral activity in HCV infected hepatocytes. 2) We will investigate the role of heme oxygenase reaction products, biliverdin/bilirubin, carbon monoxide, and iron in reducing and/or modulating oxidative stress due to the virus, and 3) We will investigate the role of HCV as a regulator of HO-1 expression, under basal conditions and in response to stress. Since HO-1 is induced in response to oxidative stress it is important to clarify how the virus must modulate HO-1 expression. This work will expand our knowledge of viral replication and hepatic injury that occur during chronic HCV infection. It will also lay a foundation for development of a novel class of antiviral agents that potentially could be adjunctive therapy for chronic HCV infection. Potential Impact on Veterans healthcare: Veterans have higher incidence rates of chronic HCV infection and suffer increased morbidity and mortality than the population at large. The results of these studies are highly likely to positively impact veterans' care with new treatment modalities and management options. PUBLIC HEALTH RELEVANCE: Hepatitis C virus is a global health problem. This work will study how the virus causes human liver disease and how the human liver responds to the virus. The importance of this work is that it will be directly applicable to treatment of humans with hepatitis C virus infection.