HCV infection, cross-talk among liver cells, and liver disease progression

 描述（由申请人提供）：丙型肝炎病毒（HCV）感染仍然是一个主要的全球健康问题。据估计，全世界有1.8亿人和美国有400万人感染HCV。慢性HCV感染仍然是肝硬化和肝细胞癌（HCC）的主要原因。尽管最近在直接作用抗病毒药物（DAA）方面取得了进展，但一些患者仍会出现终末期肝病进展。因此，了解HCV介导的肝病进展的潜在机制以寻找新的治疗靶点是至关重要的。在我们目前的赠款期间，我们提出了几个重要的意见。我们证明了HCV感染诱导自噬以保护病毒生长，并在多个步骤中损害干扰素（IFN）信号传导机制。我们还表明，HCV诱导巨噬细胞分泌IL-1β，而不清除肝细胞中的病毒。此外，我们鉴定了一组在慢性HCV感染的肝纤维化患者血清中升高的microRNA（miRNAs）。新出现的证据表明，外泌体是新发现的携带细胞间通讯的循环miRNA的载体，并且对它们在HCV介导的肝病中的作用知之甚少。我们进一步观察到一组miRNA在HCV感染肝细胞期间受到调节。基于我们的初步结果，我们假设HCV诱导的肝细胞中的miRNA通过外泌体转运到肝星状细胞（HSC）/枯否细胞（KCs），并且在HCV介导的肝脏发病机制中起关键作用。我们还预测，HCV感染后细胞内miRNA的调节会改变肝细胞的生长。为了检验我们的假设，我们提出了以下具体目标：（1）确定HCV诱导的通过外来体转运的miRNA（exo-miR）在引起肝星状细胞活化中的作用，（2）确定HCV刺激巨噬细胞/枯否细胞中的炎性细胞因子并对其他肝细胞类型施加功能性后果的机制，（3）研究HCV诱导的细胞内miRNA在原代人肝细胞生长促进中的作用。了解肝细胞之间的串扰将提供HCV介导的肝病进展的深入机制，并将有助于确定其他治疗靶点。

 DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) infection remains a major global health problem. An estimated 180 million people worldwide and 4 million people in the United States are infected with HCV. Chronic HCV infection remains a major cause of cirrhosis and hepatocellular carcinoma (HCC). Despite recent advances in direct acting antivirals (DAA), some patients experience end stage liver disease progression. Thus, it is essential to understand the underlying mechanisms of HCV mediated liver disease progression for new therapeutic targets. In our current grant period, we made several important observations. We demonstrated that HCV infection induces autophagy for protection of virus growth, and impairs interferon (IFN) signaling mechanisms at multiple steps. We have also shown that HCV induces IL-1β secretion from macrophages without clearing virus from hepatocytes. Further, we identified a group of microRNAs (miRNAs) that are elevated in sera of chronically HCV-infected liver fibrosis patients. Emerging evidence suggests that exosomes are newly identified vehicle carrying circulating miRNAs for intercellular communications and little is known about their role in HCV mediated liver disease. We further observed a group of miRNAs is modulated during HCV infection within hepatocytes. Based on our preliminary results, we hypothesize that HCV induced miRNAs in hepatocytes are transported by exosomes to hepatic stellate cells (HSCs)/Kupffer cells (KCs), and play critical roles in HCV-mediated liver pathogenesis. We also predict that modulation of intracellular miRNAs following HCV infection alters hepatocyte growth. To test our hypothesis, we propose the following specific aims: (1) determine the role of HCV induced miRNAs transported through exosomes (exo-miR) in causing hepatic stellate cell activation, (2) determine the mechanism by which HCV stimulates inflammatory cytokines in macrophages/Kupffer cells and exert functional consequence on other liver cell types, and (3) investigate the role of HCV induced intracellular miRNA in primary human hepatocyte growth promotion. Understanding the cross-talk among liver cells will provide in-depth mechanism of HCV mediated liver disease progression and will help in identifying additional therapeutic targets.