Heme Oxygenase-1 and Hepatitis C

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，引起慢性肝炎、肝硬化和肝细胞癌，在病毒感染过程中产生超氧化物和过氧化物，损害肝细胞和周围细胞。肝细胞正常上调氧化防御酶，维持氧化还原平衡，防止损伤。血红素氧化酶-1 （HO-1）是一种重要的抗氧化酶，在人类和动物模型中被诱导响应氧化应激。虽然HO-1在人类肝脏疾病中的作用尚未得到充分研究，但现有证据表明，该酶通常在损伤反应中上调。相比之下，我们小组最近的数据显示，在HCV感染的肝脏样本中，HO-1的表达下调，并且HCV核心蛋白在体外转录下调该酶。总的来说，这些数据表明HCV对HO-1表达的抑制可能导致肝损伤。我们的总体目标是确定HO-1在HCV肝脏疾病中的作用和重要性，以及当该酶被HCV下调时所导致的病理后果。我们的中心假设是HO-1是一种重要的肝细胞防御酶，可以全面预防肝细胞损伤。丙型肝炎病毒在慢性感染期间转录下调HO-1的表达，从而改变肝细胞对损伤的易感性和反应。利用大量的人肝脏样本库进行体内研究，并利用多种HCV蛋白和全长病毒构建体进行体外实验，我们将通过三个具体目的的实验来验证中心假设，并完成主要目标：1)我们将验证HCV肝病中HO-1的下调与体内肝细胞损伤显著相关并重要的假设。2)我们将验证HO-1在表达FL - HCV复制子的Huh-7.5肝细胞中转录下调的假设。3)我们将验证表达FL - HCV复制子的肝细胞对细胞损伤和氧化应激更敏感的假设。我们还假设，HO-1的过表达将至少部分逆转FL型HCV复制和表达对细胞氧化氧化还原平衡的不利影响。这些实验将增加我们对HO-1在HCV和其他肝脏疾病中的重要性的理解，以及当该酶下调时可能产生的有害后果。进一步研究HCV对HO-1表达的调控，将为改善慢性HCV患者的治疗方案奠定基础，如靶向抗氧化基因治疗和选择性抗氧化剂。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) is a global health problem, causing chronic hepatitis, cirrhosis, and hepatocellular carcinoma, 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 injury. An important antioxidative enzyme is heme oxygenase-1 (HO-1) that is induced in response to oxidative stress in humans and animal models. Although the role of HO-1 in human liver disease has not been well-studied, available evidence suggests that the enzyme is usually up-regulated in response to injury. In contrast, recent data by our group have shown that HO-1 expression is down-regulated in HCV infected liver samples and that the HCV core protein transcriptionally down-regulates the enzyme in vitro. Collectively, these data suggest that suppression of HO-1 expression by HCV may contribute to hepatic injury. Our overall objective is to determine the role and importance of HO-1 in HCV liver disease and the pathologic consequences that result when the enzyme is down regulated by HCV. Our central hypothesis is that HO-1 is an important hepatocellular defense enzyme that overall prevents hepatocyte injury. Hepatitis C virus transcriptionally down regulates expression of HO-1 during chronic infection, which alters the susceptibility and response of the hepatocyte to injury. Using a large human liver sample bank for the in vivo studies and a variety of HCV protein and full length viral constructs in vitro, we will test the central hypothesis and accomplish the major objective by undertaking experiments of three specific aims: 1) We will test the hypothesis that down regulation of HO-1 in HCV liver disease is significantly related to, and important for hepatocyte injury in vivo. 2) We will test the hypothesis that HO-1 is transcriptionally down-regulated in contrast to HO-2 in Huh-7.5 hepatocytes expressing FL HCV replicons. 3) We will test the hypothesis that hepatocytes expressing FL HCV replicons are more sensitive to cellular injury and oxidative stress. We also hypothesize that over-expression of HO-1 will at least partially reverse the untoward effects of FL HCV replication and expression on cellular oxidative redox balance. These experiments will increase our understanding of the importance of HO-1 in HCV and other liver diseases and the putative injurious consequences that result when the enzyme is down-regulated. Further study of the regulation of HO-1 expression by HCV will lay the foundation for-improved therapeutic options1 for patients with chronic HCV disease such as targeted antioxidant gene therapy and selective antioxidants.