Innate Immune Effectors in Early Immune Response to Mycobacterium Tuberculosis

描述(由申请人提供)： 结核分枝杆菌(Mtb)感染了全球约三分之一的人口。据估计，每年有800万新病例和200万人死亡，使结核病成为一个重大的健康问题。目前的结核病疫苗在预防结核病传播方面无效。此外，越来越多的美国军事人员正被部署到结核病流行地区，如阿富汗。目前迫切需要开发一种有效的结核分枝杆菌疫苗，这将需要更好地了解对控制疾病至关重要的细胞免疫反应。虽然适应性细胞免疫反应在结核病的宿主控制中是必不可少的，但导致对结核分枝杆菌产生最佳适应性细胞免疫反应所需的许多先天免疫机制仍未确定。结核分枝杆菌是通过接触气雾剂感染的，大多数结核病病例完全是肺部的。尽管如此，对人类呼吸道和肺部接触结核杆菌后发生的早期事件知之甚少，也缺乏对人类最初感染的基本特征。接触结核分枝杆菌后，呼吸道内的上皮细胞是最有可能遇到气雾化细菌的细胞。我们最近确定，原代人大气道上皮细胞一旦感染Mtb，就可以作为一种被称为粘膜相关不变T细胞(MAIT)的先天T细胞群的靶细胞，这种T细胞优先定位于肺。这项研究的长期目标是确定在人类呼吸道和肺对结核杆菌的早期免疫反应中发挥作用的先天细胞效应器。在目标1中，我们想要定义人类呼吸道中可以感染结核分枝杆菌的细胞，然后确定这些细胞中哪些可以激活天生的MAIT细胞。目的1.鉴定感染结核分枝杆菌的呼吸道细胞和激活天然MAIT细胞的细胞。假设：先天MAIT细胞是结核分枝杆菌感染细胞SA1a的一般检测器。使用免疫荧光和共聚焦显微镜确定结核分枝杆菌在呼吸道组织SA1b中的定位。识别可感染结核分枝杆菌的呼吸道细胞，并激活粘膜部位的天然MAIT细胞和上皮细胞，为抵御外来病原体提供第一道防线。呼吸道树突状细胞(DC)是启动后续获得性免疫的基本要素，位于上皮基底膜的上方和下方。在Mtb感染中，DC在启动Mtb特异性适应性T细胞方面是必不可少的，而Mtb特异性适应性T细胞对控制病原体至关重要。在这项建议中，我们想要解决的关键问题是DC如何获得呼吸道中的Mtb抗原，以及先天T细胞是否可以增强抗原呈递。目的2.确定呼吸道树突状细胞(DC)如何获得Mtb抗原。假设：树突状细胞从感染结核杆菌的呼吸道上皮细胞获得结核杆菌抗原。SA2a。评估DC如何从上皮细胞SA2b获得Mtb抗原。确定MAIT细胞在DC提呈抗原中的作用我们已经证明MAIT细胞在人类Mtb反应性非经典CD8+T细胞反应中占明显比例。然而，我们的工作表明，其他非经典CD8+T细胞群的特征仍然存在。在目标3中，我们建议克隆和鉴定这些非经典的Mtb反应性CD8+T细胞，以进一步确定人类对Mtb的先天T细胞反应。目的3.鉴定未定义的非经典限制性结核分枝杆菌反应性T细胞亚群。假设：非经典的非MAIT Mtb反应性T细胞代表新的先天T细胞亚群。Sa3a.Mtb反应的非MAIT CD8+34 TCR-T细胞的克隆和鉴定

DESCRIPTION (provided by applicant): Mycobacterium tuberculosis (Mtb) infects about one third of the population worldwide. An estimated 8 million new cases and 2 million deaths occur annually placing tuberculosis (TB) as a significant health problem. The current vaccine for TB is ineffective in preventing transmission of TB. Furthermore, an increasing number of US military personnel are being deployed to TB endemic regions such as Afghanistan. There is an urgent need to develop of an efficacious vaccine for Mtb that will require a better understanding of the cellular immune response that is critical to control the disease. While the adaptive cellular immune response is essential in the host control of TB, many of the innate immune mechanisms that are required to result in an optimal adaptive cellular immune response to Mtb remain to be characterized. Mtb is contracted by aerosol exposure and the majority of TB cases are exclusively pulmonary. Nonetheless, little is known about the early events that occur after exposure to Mtb in the human airway and lung and basic characterization of the initial infection in humans is lacking. Upon exposure to Mtb, the epithelial cells that line the airways are the cells most likely to encounter the aerosolized bacteria. We recently determined that primary human large airway epithelial cells once infected with Mtb can serve as targets for an innate T cell population known as mucosal associated invariant T (MAIT) cells that preferentially localizes to the lung. The long-term goal of this research is to identify the innate cellular effectors that play a role in the early immune response to Mtb in the human airway and lung. In Aim 1 we want to define the cells in the human airway that can be infected with Mtb and then determine which of those cells can activate innate MAIT cells. AIM 1. Identify the airway cells that are infected with Mtb and those that activate innate MAIT cells. Hypothesis: Innate MAIT cells are general detectors of Mtb-infected cells SA1a. Use immunofluorescence and confocal microscopy to identify where Mtb localizes in airway tissue SA1b. Identify airway cells that can be infected with Mtb and activate innate MAIT cells Epithelial cells at mucosal sites provide a first line of defense against foreign pathogens. Airway dendritic cells (DC), an essential element in priming subsequent adaptive immunity, are located above and below the basement member of the epithelium. In infection with Mtb, DC are essential in priming the Mtb-specific adaptive T cells that are crucial to control the pathogen. In this proposal we want to address the key question of how DC acquire Mtb antigens in the airway and if innate T cells can enhance antigen presentation. AIM 2. Determine how airway dendritic cells (DC) acquire Mtb antigens. Hypothesis: Dendritic cells acquire Mtb antigens from Mtb-infected airway epithelial cells. SA2a. Assess how DC acquire Mtb antigens from epithelial cells SA2b. Determine the role of MAIT cells in antigen presentation by DC We have shown that MAIT cells make up a demonstrable proportion of the Mtb-reactive nonclassical CD8+ T cell response in humans. However, our work suggests that additional nonclassical CD8+ T cell populations remain to be characterized. In Aim 3 we propose to clone and characterize these nonclassical Mtb-reactive CD8+ T cells to further define the innate T cell response to Mtb in humans. AIM 3. Characterize undefined subsets of nonclassically restricted Mtb-reactive T cells. Hypothesis: Nonclassical non-MAIT Mtb-reactive T cells represent novel innate T cell subsets. SA3a. Clone and characterize non-MAIT CD8+ 34 TCR- T cells that are Mtb-reactive