IL-28B genotype and HCV treatment clearance

描述（由申请方提供）：最近，通过使用蛋白酶抑制剂（特拉匹韦或博赛匹韦）与干扰素α（IFN-α）和利巴韦林一起沿着，慢性HCV感染的持续抗病毒应答得到改善。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IFN-α加利巴韦林的初始应答和IL-28基因多态性的宿主遗传变异。支持这种关联的生物学机制仍然未知。本申请使用稳定和持续感染的HCV细胞培养系统探索了IFN-λ轴如何与IFN-α/利巴韦林治疗成功相关的机制。该建议是基于几项令人兴奋和鼓舞的初步研究。我们已经开发了一种持续HCV感染的细胞培养系统，支持高水平的病毒复制，以解决IFN-α和利巴韦林联合治疗的抗病毒机制。我们报道了HCV感染本身诱导ER应激和自噬反应，选择性下调I型IFN受体，但不下调II型或III型IFN受体，受损的Stat 1/Stat磷酸化，核转位，缺陷的Jak-Stat信号传导和受损的抗病毒反应。我们已经报道了利巴韦林和IFNα各自抑制HCV IRES翻译并协同抑制HCV复制。利巴韦林耐药机制与HCV细胞培养物中核苷转运蛋白表达下调导致利巴韦林摄取受损有关。我们的研究结果表明，IFN-？对HCV有很强的抗病毒作用，在Jak-Stat缺陷和持续感染的HCV细胞培养系统中，通过激活Stat 3、AKT和MAPK途径清除HCV复制，提示III型IFN系统在清除HCV感染中起着非常重要的作用。在本R 01申请中，我们将重点了解IL-28 B多态性与IFN-α/利巴韦林抗HCV感染机制之间相关性的潜在机制，该机制在具有不同IL-28 B基因遗传背景的肝细胞系的持续感染细胞培养系统中存在。我们的假设是，丙型肝炎病毒感染本身通过下调IFNAR 1的表达产生缺陷的Jak-Stat信号传导，导致对聚乙二醇化IFN-α和利巴韦林的反应受损。为了验证这一假设，我们提出了以下三个具体目标。目的1：使用持续感染的HCV细胞培养物来检验IFN-λ轴对于HCV清除和治疗是重要的假设。目的2：研究IFN-λ克服HCV持续感染者IFN-α耐药性的机制。目的3：探讨利巴韦林对HCV感染的增效作用及耐药机制。由于IFN-λ可清除Jak-Stat缺陷型IFN-α耐药细胞中的HCV复制，因此了解本基金申请中提出的IFN-λ的信号转导和抗病毒机制将为治疗慢性HCV感染开辟新的策略。

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-α) 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-α 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-λ axis is linked to the success of IFN-α/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-α 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 IFNα 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-α/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-α and ribavirin. To test this hypothesis we propose the following three Specific Aims. Aim 1: To test hypothesis that the IFN-λ axis is important for HCV clearance and treatment using a persistently infected HCV cell culture. Aim 2: Study the mechanisms by which IFN-λ overcome IFN-α resistance of persistent HCV infection. Aim 3: To investigate the synergy and resistance mechanism of ribavirin in HCV infection. Since IFN-λ clears HCV replication in Jak-Stat defective IFN-α resistant cells, understanding the signal transduction and anti-viral mechanism of IFN-λ proposed in this grant application should open novel strategies for the treatment of chronic HCV infection.