Identifying host genetic determinants that regulate dendritic cell activation

 描述（由申请人提供）：宿主遗传多样性可能对病毒感染的易感性和疾病严重程度产生强烈影响。例如，对西尼罗河病毒（WNV）、丙型肝炎病毒（HCV）、人类免疫缺陷病毒（HIV）以及人类其他病毒感染的研究已经确定了影响病毒复制、组织嗜性、疾病严重程度的因果遗传变异和感染结果。然而，狭窄的症状窗口，加上混杂的环境因素，使得难以剖析免疫，发病机制和感染结果的遗传机制。最近的国际努力开发了一种新的小鼠遗传资源，称为协作交叉（CC），旨在模拟人类基因组的复杂性，并支持综合系统遗传学方法来了解复杂的人类疾病（例如宿主对病毒感染的反应）。CC是唯一的哺乳动物资源，具有由高度和均匀的基因组范围内的变异组成的无限可再生的群体。事实上，CC被用于研究各种医学相关的特征，包括肥胖，精神疾病，癌症，自身免疫，以及确定真菌，细菌和病毒感染的风险因素。目前，人们对遗传多样性如何影响先天免疫信号对病毒感染和疫苗接种的反应知之甚少。我们试图弥补我们知识中的这一差距。我们假设宿主遗传变异影响树突状细胞（DC）内的先天免疫感应和抗病毒反应。RIG-I样受体（RLR）是模式识别受体，其对于诱导I型干扰素（IFN）、抗病毒基因表达和促进响应于WNV和其它RNA病毒感染的B和T细胞免疫是必需的。我们最近观察到，WNV感染的原代小鼠胚胎成纤维细胞来源于八个CC创始人菌株表现出不同的动力学和IFN-γ诱导的幅度。通过初步筛选以评估衍生自一组CC系的DC内的RIG-I信号传导，我们鉴定了相对于C57 BL/6 J小鼠差异性地触发IFN-γ表达的高响应性（AU 8005增加17.8倍）和低响应性CC系（OR 3032降低9.8倍）。支持 我们的发现，最近在人类单核细胞和DC中的分析确定了影响Toll样受体信号传导和对流感病毒感染的抗病毒反应的因果遗传变异。为了研究我们的假设，我们将使用涉及遗传学，免疫学，病毒学和系统生物学的跨学科方法来鉴定调节RLR信号传导和DC先天免疫应答的遗传变异。具体而言，我们将：1）研究遗传多样性对先天免疫感应的影响;和2）鉴定调节DC中RLR信号传导的遗传变体。这些研究将为宿主遗传学和先天免疫信号传导提供更深入的了解，并为免疫调节药物的开发奠定基础，这些药物可以更有效地激活广泛遗传背景下的先天适应性免疫界面。

 DESCRIPTION (provided by applicant): Host genetic diversity can have a strong impact on susceptibility to viral infection and disease severity. For instance, studies with West Nile virus (WNV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), as well as other viral infections in humans, have identified causal genetic variants that influence viral replication, tissue tropism, disease severity, and infection outcome. However, narrow windows of symptoms, combined with confounding environmental factors, have made it difficult to dissect the genetic mechanisms underlying immunity, pathogenesis and infection outcome. Recent international efforts have developed a novel mouse genetic resource, called the Collaborative Cross (CC), designed to model the complexities of the human genome and support an integrative systems genetics approach to understand complex human diseases (e.g. host response to virus infection). The CC is the only mammalian resource with an infinitely reproducible population comprised of high and uniform genome wide variation. In fact, the CC is being used to study diverse medically-relevant traits, including obesity, psychiatric disorders, cancer, autoimmunity, as well as to identify risk factors of fungal, bacterial, and viral infection. At this time, little is known about how genetic diversity influences innate immune signaling in response to virus infection and vaccination. We seek to address this gap in our knowledge. We hypothesize that host genetic variation impacts innate immune sensing and antiviral responses within dendritic cells (DCs). The RIG-I like receptors (RLRs) are pattern recognition receptors that are essential for inducing type I interferon (IFN), antiviral gene expression and promoting B and T cell immunity in response to WNV and other RNA virus infections. We recently observed that WNV-infected primary mouse embryonic fibroblasts derived from the eight CC founder strains exhibited differences in kinetics and magnitude of IFN-ß induction. Through a preliminary screen to evaluate RIG-I signaling within DCs derived from a set of CC lines, we identified a hyper-responsive (AU8005 17.8 fold increased) and hypo-responsive CC line (OR3032- 9.8 fold decreased) that differentially triggered IFN-ß expression relative to C57BL/6J mice. In support of our findings, a recent analysis within human monocytes and DCs identified causal genetic variants that impact toll-like receptor signaling and the antiviral response to influenza virus infection. To investigate our hypothesis, we will use an interdisciplinary approach involving genetics, immunology, virology, and systems biology to identify genetic variants that regulate RLR signaling and DC innate immune responses. Specifically, we will: 1) investigate the impact of genetic diversity on innate immune sensing; and 2) identify genetic variants that regulate RLR signaling in DCs. These studies will provide a greater insight into host genetics and innate immune signaling and establish a foundation for development of immune-modulatory drugs that can more efficiently activate the innate-adaptive immune interface across a wide range of genetic backgrounds.