Lung-resident antibacterial heterotypic immunity

摘要 拟议的研究将阐明细胞和分子机制，组织活动，命运， 肺中CD 4 + T细胞的组织定位。CD 4 + T细胞通过抗原呈递来指导， MHC-II和共刺激或检查点分子。我们的初步数据显示，MHC-II广泛存在于 由肺上皮细胞表达，并在肺炎球菌感染缓解期间和之后动态调节。 肺炎此外，我们观察到不同亚型的肺上皮细胞表达不同的模式， 共刺激分子和检查点分子。我们认为上皮细胞MHC-II与细胞类型特异性的 表达共刺激和检查点分子以适当地指导CD 4 + T细胞，定位CD 4 + T细胞， 细胞活性和适应性免疫的所有方面，依赖于肺CD 4 + T细胞， 区域（传导气道）和远离更脆弱和要求更高的元素（肺泡），以增加 免疫抵抗力，同时减少肺损伤。我们的中心假设是肺上皮上的MHC-II 将适应性免疫力驱动到传导气道，远离肺泡，通过追踪 具体目的如下：（1）验证肺上皮细胞指导解剖学的假设， 肺中CD 4 + T细胞的分离。这将使用多种显微镜方法来实现， 记录CD 4+细胞扩增和收缩的区域动力学和上皮相互作用， 在肺炎后，对于MHC-II，上皮细胞是亮的与暗的，而对于MHC-II， MHC-II遍布整个肺上皮。(2)测试肺泡上皮II型细胞使用MHC- II加PD-L1以限制炎性肺损伤。这将通过PD-L1阻断、条件性 肺泡上皮II型细胞中的MHC-II突变，以及具有MHC-II突变的不同类型的II型细胞的RNAseq。 MHC-II和检查点分子的不同模式。(3)检验气道俱乐部细胞和 多纤毛细胞使用MHC-II加上CD 40来支持抗微生物防御。这将通过使用 在俱乐部细胞和多纤毛细胞中MHC-II或CD 40的条件突变。总之，这些研究将 揭示肺炎期间肺上皮细胞是否以及如何协调CD 4 + T细胞活动， 确定感染消退后的TRM细胞生态位。结果将确定自然获得性免疫 在年龄较大的儿童和年轻健康成人中预防肺炎的机制， 在肺中的呈递途径，并阐明检查点和共刺激分子在指导 肺CD 4 + T细胞生物学。

Abstract The proposed studies will elucidate cellular and molecular mechanisms that organize the activities, fate, and tissue localizations of CD4+ T cells in the lungs. CD4+ T cells are instructed by antigen presentation from MHC-II and costimulatory or checkpoint molecules. Our preliminary data reveal that MHC-II is widely expressed by lung epithelial cells, and dynamically regulated during and after resolution of pneumococcal pneumonia. Furthermore, we observe that distinct sub-types of lung epithelial cells express different patterns of costimulatory and checkpoint molecules. We propose that epithelial cell MHC-II pairs with cell-type-specific expression of costimulatory and checkpoint molecules to appropriately instruct CD4+ T cells, localizing CD4+ T cell activities and all aspects of adaptive immunity that depend on lung CD4+ T cells near more forgiving regions (conducting airways) and away from more fragile and demanding elements (alveoli), to increase immune resistance while diminishing lung injury. Our central hypothesis is that MHC-II on the lung epithelium drives adaptive immunity toward the conducting airways and away from the alveoli, to be tested by pursuing the following specific aims: (1) Test the hypothesis that pulmonary epithelial cells direct the anatomical segregation of CD4+ T cells in the lung. This will be accomplished using multiple microscopy approaches to document the regional kinetics and epithelial interactions of CD4+ cell expansion and contraction during and after pneumonia, RNAseq of epithelial cells that are bright vs. dim for MHC-II, and conditional mutation of MHC-II throughout all the lung epithelium. (2) Test the hypothesis that alveolar epithelial type II cells use MHC- II plus PD-L1 to limit inflammatory lung injury. This will be accomplished using PD-L1 blockade, conditional mutation of MHC-II in alveolar epithelial type II cells, and RNAseq of disparate classes of type II cells with distinct patterns of MHC-II and checkpoint molecules. (3) Test the hypothesis that airway club cells and multiciliated cells use MHC-II plus CD40 to bolster antimicrobial defense. This will be accomplished using conditional mutation of MHC-II or of CD40 in both club cells and multiciliated cells. Altogether, the studies will reveal whether and how lung epithelial cells orchestrate CD4+ T cell activities during pneumonia and determine the TRM cell niche after resolution of infection. Results will identify naturally acquired immune mechanisms that prevent pneumonia in older children and young healthy adults, provide insight into antigen presentation pathways in the lung, and elucidate roles of checkpoint and costimulatory molecules in directing lung CD4+ T cell biology.