Early Regulation of Immunity in the Respiratory Tract

描述(申请人提供)：呼吸道是病原体最重要的进入部位之一，包括许多潜在的生物恐怖主义因素，如流感病毒。虽然已知局部先天和早期获得性免疫防御对于限制病原体的初始传播至关重要，但呼吸道粘膜免疫的基础机制仍不清楚。肺组织树突状细胞(DC)是先天免疫系统的关键组成部分，通过迁移到区域淋巴结将抗原递呈给T细胞来调节适应性免疫。初步数据表明，与目前的教条相反，DC还可以激活肺组织本身的免疫反应。本应用的目的是确定流感病毒感染激活的呼吸道DC调节局部病毒特异性T和B细胞反应的机制，并测试灭活病毒(作为原型疫苗)的应用如何影响它们的功能。这项研究的中心假设是，肺组织DC的感染对于他们向B细胞递送抗原和调节病毒特异性CD4T细胞反应的能力至关重要。提出了以下具体目标：具体目标1是通过研究DC的表型及其病毒和宿主基因的体外表达，并确定它们调节病毒特异性T依赖和/或T非依赖B细胞反应的机制，全面表征A/PR8流感小鼠亚致死感染后呼吸道DC的反应。具体目标#2将通过在与病毒刺激的呼吸道DC共培养和过继转移DC后体内测量初始和激活的CD4+T细胞的细胞因子谱和克隆性突发大小，来确定肺组织和引流淋巴结DC调节病毒特异性效应器CD4T细胞反应的诱导和/或质量的能力。具体目的#3是确定灭活病毒的应用是否会导致局部DC群体在表型、基因表达谱或效应器功能上与活病毒感染诱导的DC群体不同；因此，与活性感染后获得的保护水平相比，灭活病毒疫苗诱导的DC反应质量的差异是否可能是导致通常令人失望的保护水平的基础。综上所述，这项研究将提供对呼吸道DC生物学的详细了解，特别是它们在调节病原体进入部位的早期局部反应中的作用。这些信息可能有助于开发利用早期呼吸道防御进行免疫保护的新干预措施。

DESCRIPTION (provided by applicant): The respiratory tract is one of the most important sites of entry for pathogens including many potential bioterrorism agents such as influenza virus. Although local innate and early adaptive immune defenses are known to be crucial for limiting initial pathogen spread, the mechanisms underlying mucosal immunity in the respiratory tract are still poorly defined. Lung tissue dendritic cells (DC) are key components of the innate immune system that regulate adaptive immunity by migrating to the regional lymph nodes to present antigens to T cells. Preliminary data suggest that contrary to current dogma, DC can also activate immune responses in the lung tissue itself. The objective of this application is to determine the mechanisms by which respiratory tract DC activated by influenza virus-infection regulate local virus-specific T and B cell responses and to test how application of inactivated virus (as a prototype vaccine) affects their functions. The central hypothesis underlying this study is that infection of lung tissue DC is critical for their ability to present antigen to B cells and to regulate virus-specific CD4 T cell responses. The following Specific Aims are proposed: Specific Aim #1 is to fully characterize respiratory tract DC responses following sublethal infection of mice with influenza A/PR8, by studying the phenotype of DC and their viral- and host-gene expression ex vivo and to determine the mechanisms by which they regulate virus-specific T-dependent and/or T-independent B cell responses. Specific Aim #2 will determine the ability of lung tissue and draining lymph node DC to regulate the induction and/or quality of virus-specific effector CD4 T cell responses, by measuring cytokine profiles and clonal burst sizes of naive and activated CD4+T cells in co-cultures with virus-stimulated respiratory tract DC and in vivo following adoptive transfer of DC. Specific Aim #3 is to determine whether application of inactivated virus induces local DC populations that differ in phenotype, gene expression profile or effector function from those induced by live virus infection; thus whether differences in the quality of the DC responses induced to live and inactivated virus could underlie the often disappointing levels of protection achieved with inactivated virus vaccines compared to those obtained after active infection. In summary, this study will provide a detailed understanding of respiratory tract DC biology, particularly their role in regulating early local responses at the site of pathogen entry. This information could help the development of novel interventions that utilize early respiratory tract defenses for immune protection.