Cyclophilins and the IFN Response

描述（由申请方提供）：在I期和II期研究中，亲环素（Cyp）抑制剂（CypI）在HCV患者中具有高度临床效力。最近的一项I期研究表明，每天给予CypI可减少病毒血症，并迅速增加IFNα、λ1和λ3以及2 '5'OAS-1的血浆浓度。所有标记物的血浆浓度变化与CypI的血浆浓度变化一致。这些新的和有吸引力的数据揭示了Cyps和IFN应答之间的第一个联系。我们能够在体外部分重现患者数据。具体地说，CypI增强了 来自复制子细胞的IFNα、λ和2 '5'OAS-1。这些数据表明，IFN应答的激活可能代表CypI发挥其临床抗病毒活性的机制。我们研究了CypI，CypA的细胞内目标，结合到IFN反应的组件的可能性。值得注意的是，我们发现CypA通过其异构酶口袋与IFN调节因子9（IRF 9）结合。CypI阻止IRF 9-CypA相互作用。CypA还与IRF 3、5和7结合，表明CypA与所有IRF成员结合。我们的工作首次证明CypA特异性结合IFN应答的主要类别元素- IRFs。这也揭示了一个新的机会，调节IFN反应。在此应用中，我们建议通过进行一系列旨在解剖CypA在IFN应答中的作用的实验来扩展这项工作。本申请应阐明CypA中和如何触发IFN产生，并确定CypI介导的IFN产生是否代表CypI抗病毒作用的新机制。该应用程序还应确定CypA对IRF的作用或功能。有趣的是，我们最近的工作表明，CypA通过与IRF相互作用，极大地影响了它们的泛素化程度。我们提出了一组新的实验，旨在确定CypA介导的IRF泛素化效应和CypI介导的IFN应答激活之间的联系。我们的发现CypI触发从HCV患者分离的PBMC中释放IFN开辟了令人兴奋的新的查询线。这种离体测定可以使我们确定CypI应答者是否比CypI无应答者产生更多的IFN，以及CypI应答是否是基因型特异性的或病毒滴度特异性的。如果发生这种情况，我们将使用这些信息来为受试者开发经验性预筛选，这些受试者可能对包含CypI的方案有反应。我们最近发现，CypI给药小鼠显着抑制病毒的感染性，这是无关的HCV，但也是高度敏感的IFN。此外，我们发现，与未处理的感染小鼠相比，用CypI处理的感染小鼠的IFN血浆水平是上级的，这表明CypI IFN诱导是更广泛使用的机制。这些令人瞩目的初步发现开辟了令人兴奋的研究新领域。本申请的最终目标是提高我们对Cyps在IFN对病毒感染的应答中的作用的理解。

DESCRIPTION (provided by applicant): Cyclophilin (Cyp) inhibitors (CypI) are clinically highly potent in HCV patients in phase I and II studies. A recent phase I study showed that the daily administration of a CypI reduces viremia and rapidly increases plasma concentrations of IFNα, λ1 and λ3, and 2'5'OAS-1. Changes in plasma concentrations for all markers were coincident with changes in plasma concentration of the CypI. These novel and attractive data revealed the first link between Cyps and the IFN response. We were able to partly reproduce the patient data in vitro. Specifically, CypI enhance secretion of IFNα, λ and 2'5'OAS-1 from replicon cells. These data suggest that activation of the IFN response may represent a mechanism through which CypI exert their clinical antiviral activity. We investigated the possibility that the intracellular target for CypI, CypA, binds to components of the IFN response. Remarkably, we found that CypA binds to the IFN regulatory factor 9 (IRF9) via its isomerase pocket. CypI prevent IRF9-CypA interactions. CypA also binds to IRF3, 5 and 7, suggesting that CypA binds to all IRF members. Our work demonstrates for the first time that CypA binds specifically to a major class of elements of the IFN response - IRFs. It also reveals a novel opportunity to modulate the IFN response. In this application, we propose to extend this work by conducting a series of experiments aimed at dissecting the roles of CypA in the IFN response. This application should elucidate how CypA neutralization triggers IFN production and determine whether the CypI-mediated IFN production represents a new mechanism of antiviral action of CypI. This application should also determine what action or function CypA exerts on IRFs. Interestingly, our most recent work suggests that CypA, by interacting with IRFs, greatly impacts their degree of ubiquitination. We propose a new set of experiments aimed at identifying the link between the CypA-mediated IRF ubiquitination effect and the CypI-mediated activation of the IFN response. Our finding that CypI triggers IFN release from PBMCs isolated from HCV patients opens exciting new lines of enquiries. This ex vivo assay may allow us to determine whether CypI responders produce more IFN than CypI non-responders and whether the CypI response is genotype- or virus titer-specific. If this occurs, we then would use this information t develop an empiric pre-screen for subjects, who are likely to respond to a regimen comprising a CypI. We recently found that CypI administration to mice significantly inhibits the infectivity of virus, which is unrelated to HCV, but which is also highly sensitive to IFN. Moreover, we found that the IFN plasma levels were superior in infected mice treated with CypI compared to those in untreated infected mice, suggesting that the CypI IFN induction is a more widely used mechanism. These remarkable preliminary finding opened new lines of exciting enquiries. The ultimate goal of this application is to improve our understanding of the role of Cyps in the IFN response to viral infection.