IL-28B genotype and HCV treatment clearance

描述(由申请人提供)：最近，通过使用蛋白酶抑制剂(telaprevir或bocprevir)以及干扰素和利巴韦林，慢性丙型肝炎病毒感染的持续抗病毒反应得到了改善。然而，最近的临床试验结果表明，三联疗法的最终结果强烈依赖于患者对干扰素加利巴韦林的初始反应和IL-28基因多态性的宿主遗传变异。支撑这种联系的生物学机制仍不清楚。目前的应用探索了干扰素-？AXIS与使用稳定和持续感染的丙型肝炎病毒细胞培养系统进行干扰素/利巴韦林治疗的成功有关。该提案是基于几项令人振奋和鼓舞人心的初步研究。我们开发了一种持续感染丙型肝炎病毒的细胞培养系统，支持高水平的病毒复制，以解决干扰素和利巴韦林联合治疗的抗病毒机制。我们报道，丙型肝炎病毒感染本身可以诱导内质网应激和自噬反应，选择性地下调I型干扰素受体，而不下调II型或III型干扰素受体，受损的STAT1/Stat磷酸化，核易位，Jak-Stat信号缺陷和抗病毒反应受损。我们已经报道，利巴韦林和干扰素分别抑制丙型肝炎病毒IRES的翻译，并协同抑制丙型肝炎病毒复制。利巴韦林耐药机制与丙型肝炎病毒细胞培养中核苷转运蛋白表达下调导致利巴韦林摄取受损有关。结果表明，干扰素-？具有很强的抗病毒作用，并通过激活STAT3、AKT和MAPK通路，清除Jak-Stat缺陷和持续感染的丙型肝炎病毒细胞培养系统中的丙型肝炎病毒复制，提示III型干扰素系统在清除丙型肝炎病毒感染中起着非常重要的作用。在R01的应用中，我们将重点了解在具有不同IL-28B基因遗传背景的肝细胞系中，在持续感染细胞培养系统中，IL-28B基因多态性与干扰素/利巴韦林抗病毒机制之间的关联机制。我们的假设是，丙型肝炎病毒感染本身通过下调IFNAR1的表达而产生缺陷的Jak-Stat信号，从而导致对聚乙二醇化的干扰素和利巴韦林的反应减弱。为了验证这一假设，我们提出了以下三个具体目标。目的1：检验假设干扰素-？AXIS对于丙型肝炎病毒清除和使用持续感染的丙型肝炎病毒细胞培养进行治疗非常重要。目的2：研究干扰素-？克服持续性丙型肝炎病毒感染的干扰素抵抗。目的：探讨利巴韦林对丙型肝炎病毒感染的协同作用及其耐药机制。自从干扰素-？清除Jak-Stat缺陷的干扰素抵抗细胞中的丙型肝炎病毒复制，了解干扰素-β的信号转导和抗病毒机制。在这项赠款申请中提出的建议将开启治疗慢性丙型肝炎病毒感染的新策略。

DESCRIPTION (provided by applicant): The sustained antiviral response of chronic HCV infection has been improved recently by the use of the protease inhibitor (telaprevir or boceprevir) along with interferon alpha (IFN-¿) and ribavirin. However, results of recent clinical trials indicate that the final outcome of triple combination therapy is strongly dependent on the patient's initial response to IFN-¿ plus ribavirin and the host genetic variation of IL-28 gene polymorphism. The biological mechanisms underpinning this association remain unknown. The current application explores mechanisms for how the IFN-? axis is linked to the success of IFN-¿/ribavirin treatment using a stable and persistently infected HCV cell culture system. The proposal is based on several exciting and encouraging preliminary studies. We have developed a persistently HCV infected cell culture system that supports high- level viral replication to address the antiviral mechanisms of IFN-¿ and ribavirin combination treatment. We reported that HCV infection itself induces ER-stress and autophagy response that selectively down regulates the type-I IFN receptor but not the type-II or type-III IFN receptor, impaired Stat1/Stat phopshorylation, nuclear translocation, defective Jak-Stat signaling and impaired antiviral response. We have reported that ribavirin and IFN¿ each inhibit HCV IRES translation and synergistically inhibit HCV replication. The ribavirin resistance mechanism relates to the impaired ribavirin uptake due to the down-regulated expression nucleoside transporters in HCV cell culture. Our results indicate that IFN-? has a strong antiviral action against HCV and it clears HCV replication to a completion in Jak-Stat defective and persistently infected HCV cell culture system through activation of Stat3, AKT and MAPK pathways suggesting that the type III IFN system plays a very important role in the clearance of HCV infection. In this R01 application, we will focus on understanding the mechanism underlying the association between IL28B polymorphisms and IFN-¿/ribavirin antiviral mechanisms of HCV infection in a persistent infectious cell culture system in hepatocyte cell lines with a different genetic background of IL-28B gene. Our hypothesis is that hepatitis C virus infection itself creates defective Jak-Stat signaling by down regulating the expression of IFNAR1 that leads to impaired response to pegylated IFN-¿ and ribavirin. To test this hypothesis we propose the following three Specific Aims. Aim 1: To test hypothesis that the IFN-? axis is important for HCV clearance and treatment using a persistently infected HCV cell culture. Aim 2: Study the mechanisms by which IFN-? overcome IFN-¿ resistance of persistent HCV infection. Aim 3: To investigate the synergy and resistance mechanism of ribavirin in HCV infection. Since IFN-? clears HCV replication in Jak-Stat defective IFN-¿ resistant cells, understanding the signal transduction and anti-viral mechanism of IFN-? proposed in this grant application should open novel strategies for the treatment of chronic HCV infection.