Lung-resident antibacterial heterotypic immunity

摘要 拟议中的研究将阐明组织活动、命运和 肺内CD4T细胞的组织定位。CD4T细胞受来自于 MHC-II和共刺激分子或检查点分子。我们的初步数据显示，MHC-II广泛存在 肺炎球菌在肺上皮细胞中的表达及消退过程中和消退后的动态调节 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与细胞类型特异性配对 表达共刺激分子和检查点分子以适当地指示CD4T细胞，定位CD4T 细胞活动和适应性免疫的方方面面依赖于肺CD4T细胞近乎更宽容 区域(导气管)和远离更脆弱和要求更高的元素(肺泡)，以增加 免疫抵抗的同时减轻肺损伤。我们的中心假设是肺上皮细胞上的MHC-II 将适应性免疫推向传导气道，远离肺泡，通过以下方式进行测试 具体目标如下：(1)检验肺上皮细胞指导解剖结构的假设 肺内CD4T细胞的分离。这将使用多种显微镜方法来完成 记录CD_4细胞扩张和收缩的区域动力学和上皮相互作用 肺炎后，MHC-II亮与暗的上皮细胞的RNAseq，以及条件突变 MHC-II分布于所有肺上皮细胞。(2)验证肺泡上皮II型细胞使用MHC- II加PD-L1以限制炎性肺损伤。这将使用PD-L1封锁来完成，有条件的 肺泡II型上皮细胞中MHC-II的突变，以及不同类型的II型细胞的RNAseq MHC-II和检查点分子的不同模式。(3)检验以下假设：呼吸道俱乐部细胞和 多纤毛细胞使用MHC-II加CD40来加强抗菌防御。这将通过以下方式完成 杆状细胞和多毛细胞中MHC-II或CD40的条件性突变。总而言之，这些研究将 揭示肺炎和肺炎期间肺上皮细胞是否以及如何协调CD4T细胞活动 感染消退后确定TRM细胞生态位。结果将确定自然获得性免疫 预防大龄儿童和年轻健康成人肺炎的机制提供了对抗原的洞察 肺内的递呈途径，并阐明检查点和共刺激分子在引导 肺CD4T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.