Role of CD11c in CD8 T cell response to infection

描述(由申请人提供)：整合素是免疫系统的关键组成部分，通过其活动指导淋巴细胞的发展、移动和激活。B2-整合素CD11c在体内的功能在很大程度上尚不清楚。我们的数据表明，CD11c是在原代和记忆性CD8T细胞上诱导的，对感染有反应。此外，在缺乏CD11c的情况下，CD8T细胞的反应严重减弱，这表明CD11c在驱动CD8T细胞激活方面发挥了完整的共刺激作用。本文提出的研究将验证CD11c通过在激活后早期促进T细胞-DC相互作用来控制CD8 T细胞反应的假设。分析CD11c共刺激的机制有三个具体目的：1.确定CD11c在早期CD8T细胞感染应答中的作用。使用细菌和病毒感染与CD11c缺陷的CD8T细胞，将测试CD11c在促进CD8T细胞的增殖、分化和存活方面的作用。具体目的2.分析CD8T细胞表达的CD11c在确定感染免疫应答的解剖学中的作用。我们的初步结果使用原位MHC I类四聚体染色确定了一系列阶段性事件，这些事件驱动CD8 T细胞在感染单核细胞增多性李斯特菌后被激活。使用共聚焦显微镜的原位分析将评估CD11c在响应的内源性和过继转移的CD8T细胞的激活和运动中的作用。具体目的3.分析CD11c在树突状细胞发育和功能中的作用。DC高水平表达CD11c，提示CD11c在DC功能中具有重要作用。然而，由于缺乏可靠的DC鉴定标记物，对CD11c缺陷DC的分析比较复杂。我们已经培育出了在CD11c启动子控制下表达荧光报告蛋白的转基因小鼠，以规避这一问题。当这些小鼠出现CD11c缺陷时，将提供在动态平衡或感染条件下跟踪和分析CD11c-/-DC的手段。总之，这些研究将首次分析CD11c在CD8T细胞和DC激活中的作用。公共卫生研究：这项建议的重点是了解一种特殊的黏附分子，整合素CD11c，在细菌感染后CD8T细胞激活中的作用。CD8T细胞是一种细胞毒性淋巴细胞，参与了对感染细胞的杀伤作用，并在抵御细胞内细菌感染方面发挥着核心作用。因此，这项研究对理解对感染的免疫力具有重大影响，并对有效疫苗的设计具有重要意义。

DESCRIPTION (provided by applicant): Integrins are critical components of the immune system through their activities in directing lymphocyte development, movement and activation. The function of the b2-integrin CD11c in vivo is largely unexplored. Our data show that CD11c is induced on primary and memory CD8 T cells responding to infection. Moreover, in the absence of CD11c, the CD8 T cell response is severely diminished indicating an integral costimulatory role for CD11c in driving CD8 T cell activation. The studies proposed here will test the hypothesis that CD11c controls CD8 T cell response by promoting T cell- DC interactions early after activation. Three specific aims are proposed to analyze the mechanisms of CD11c costimulation: Specific Aim 1. To determine the role of CD11c in the early CD8 T cell response to infection. Using bacterial and viral infections in conjunction with CD11c-deficient CD8 T cells, the role of CD11c in promoting proliferation, differentiation and survival of CD8 T cells will be tested. Specific Aim 2. To analyze the role of CD11c expressed by CD8 T cells in determining the anatomy of the immune response to infection. Our preliminary results using in situ MHC class I tetramer staining identified a series of stepwise events that drive CD8 T cell activation in response to infection with Listeria monocytogenes. In situ analysis using confocal microscopy will be performed to assess the role of CD11c in activation and movement of responding endogenous and adoptively transferred CD8 T cells. Specific Aim 3. To analyze the role of CD11c in development and function of dendritic cells. The high level expression of CD11c by DC strongly suggests an important role for CD11c in DC function. However, the analysis of CD11c-deficient DC is complicated due to the lack of a reliable marker for DC identification. We have produced transgenic mice expressing a fluorescent reporter protein under control of the CD11c promoter to circumvent this issue. These mice, when rendered CD11c-deficient, will provide the means to track and analyze CD11c-/- DC under conditions of homeostasis or infection. In sum, these studies will provide the first analysis of the role of CD11c in CD8 T cell and DC activation. PUBLIC HEALTH RELEVENCE: This proposal is focused on understanding the role of a specialized adhesion molecule, the integrin CD11c, in CD8 T cell activation in response to a bacterial infection. CD8 T cells are cytotoxic lymphocytes involved in killing of infected cells and play a central role in protection against intracellular bacterial infections. Therefore, this research has substantial impact on understanding immunity to infection and holds implications for design of effective vaccines.