Heme Oxygenase-1 Inhibition of Hepatitis C Replication

描述（由申请人提供）： 丙型肝炎病毒（HCV）是一种全球性的健康问题，可引起慢性肝炎、肝硬化和肝细胞癌。近50%的感染患者对干扰素治疗无反应，因此开发其他治疗方式至关重要。肝损伤可能是由病毒感染期间产生的超氧化物和过氧化物等氧化剂引发的，并损害肝细胞和周围细胞。肝细胞通常上调氧化防御酶以维持氧化还原平衡并防止肝损伤。血红素加氧酶-1（HO-1）是一种氧化防御酶，在氧化应激反应中被诱导。该酶的反应产物胆绿素、一氧化碳和铁在细胞中发挥重要作用，以维持细胞止血和防止损伤。我们实验室过去的工作表明，HCV可以转录调节HO-1的表达。最近，我们报道HO-1过表达或用氯化血红素诱导可以减弱病毒复制，同时保护HCV复制子细胞免受氧化损伤。因此，我们的研究结果强烈表明，HO-1诱导药物，如氯化血红素可能是一个新的令人兴奋的途径，连续抗病毒治疗，以治疗HCV感染和/或预防慢性肝病。本申请的主要目的是表征HO-1诱导及其酶促产物抑制HCV复制并降低氧化应激的细胞机制。本申请的中心假设是HO-1是一种重要的肝细胞防御酶，其反应产物减弱HCV复制以及保护免受病毒引起的氧化损伤。我们将利用已建立的HCV非结构复制子和全长复制子的细胞系以及支持HCV体外细胞生命周期的JFH 6细胞系，通过以下三个具体目标的实验来验证中心假设并实现主要目标：1）我们将研究HO反应产物铁和胆绿素/胆红素作为HCV感染肝细胞中HO-1抗病毒活性的介导剂的作用。2)我们将研究血红素加氧酶反应产物、胆绿素/胆红素、一氧化碳和铁在减少和/或调节病毒引起的氧化应激中的作用，以及3）我们将研究HCV在基础条件下和应激反应中作为HO-1表达调节剂的作用。由于HO-1是诱导响应氧化应激，重要的是要澄清如何病毒必须调节HO-1的表达。这项工作将扩大我们对慢性HCV感染过程中病毒复制和肝损伤的认识。这也将为开发一类新的抗病毒药物奠定基础，这些药物可能是慢性HCV感染的有效治疗方法。对退伍军人医疗保健的潜在影响：退伍军人慢性HCV感染的发病率较高，发病率和死亡率高于一般人群。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，提供新的治疗方式和管理选择。 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引起人类肝脏疾病以及人类肝脏如何对病毒作出反应。这项工作的重要性在于，它将直接适用于治疗丙型肝炎病毒感染的人类。

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.