Recognition of Mtb-Infected Cells by Non-Classically Restricted CD8+ T Cells

项目摘要 结核病（TB）是全世界传染病死亡的主要原因， 每年有130万人死亡。了解对结核分枝杆菌的免疫反应至关重要 在改进疫苗的研发中。在这方面，我们的实验室，在VA Merit的赞助下， 已经将粘液相关的不变T（MAIT）细胞定义为一类受免疫调节因子限制的细胞。 高度保守的MR1分子，识别Mtb感染的细胞，在胸腺和脐带中具有效应子能力 血液中，但显示证据的记忆暴露于结核分枝杆菌，并在肺部富集。 MAIT细胞存在于肺和肠等组织中。因为MAIT细胞识别小分子， 如核黄素的代谢产物，我们推测MR1的细胞表面表达受到严格调控， 避免在没有细胞内感染的情况下激活这些细胞。事实上，在VA Merit的支持下， 程序中，我们发现MR1既位于一个内体中，又需要一个配体才能易位到细胞中 表面，并依赖于囊泡运输的Mtb衍生抗原的MR1T细胞的介绍。 此外，我们发现Mtb衍生抗原的呈递机制可以区分为 来自外源性抗原，这表明有专门的采样机制， 细胞内环境。 因此，在本申请中，我们将集中于定义允许适当的分子机制。 呈现细胞内感染，重点是Mtb。我们将1）定义所需的分子伴侣 2）确定MR1 SNP和剪接变体在控制微生物配体中的作用， Mtb感染细胞的识别，并将在以下临床相关结果中评估这些变体 暴露于结核分枝杆菌 该项目有两个目标： 目的1：确定结核分枝杆菌衍生配体呈递所必需的分子伴侣 1a.确定与MR1相关的分子伴侣。 1b.确定核黄素转运蛋白在MR1配体摄取或运输中的作用。 目的2：确定MR1单核苷酸多态性和剪接变异体在人类结核病易感性中的作用 2a.确定MR1 SNPs和剪接变异体与以下相关临床结局的关系： 暴露于结核分枝杆菌 2b.确定MR1 SNP的功能意义。 2c.确定MR1剪接变体表达与细胞呈递MR1能力的关系 MR1T细胞的配体。

Project Summary Tuberculosis (TB) is a leading cause of infectious disease mortality worldwide, accounting for 10.4 million new cases and 1.3 million deaths annually. An understanding of the immune response to Mtb is of central importance in the development of improved vaccines. In this regard our laboratory, under the auspices of the VA Merit Program, has defined Mucosal Associated Invariant T (MAIT) cells as a class of cells that are restricted by the highly conserved MR1 molecule, recognize Mtb-infected cells, have effector capacity in the thymus and cord blood, yet display evidence for memory following exposure to Mtb, and are enriched in the lungs. MAIT cells are found in tissues such as the lung and intestine. Because MAIT cells recognize small molecules, such as metabolites of riboflavin, we postulate that the cell surface expression of MR1 is tightly regulated to avoid activation of these cells in the absence of intracellular infection. Indeed, with the support of the VA Merit Program, we have found that MR1 is both located in an endosome, requires a ligand for translocation to the cell surface, and is dependent on vesicular trafficking for the presentation of Mtb-derived antigens to MR1T cells. Furthermore, we find that the mechanisms underlying presentation of Mtb-derived antigens can be distinguished from antigens that are exogenously delivered, suggesting that there are specialized mechanisms for sampling the intracellular environment. Therefore, in this application we will focus on defining the molecular mechanisms that allow for the appropriate presentation of intracellular infection, with a focus on Mtb. We will 1) Define the molecular chaperones required for the presentation of microbials ligands, and 2) Define the role of MR1 SNPs and splice variants in controlling the recognition of the Mtb infected cell, and will evaluate these variants in clinically relevant outcomes following exposure to Mtb. This project contains two Aims: AIM 1: Define the molecular chaperones necessary for the presentation of Mtb-derived ligands 1a. Determine the molecular chaperones associated with MR1. 1b. Determine the role of riboflavin transporters in the uptake or trafficking of MR1 ligands. AIM 2: Define the role of MR1 SNPs and splice variants in human susceptibility to TB 2a. Determine the relationship of MR1 SNPs and splice variants and clinical outcomes associated with exposure to Mtb. 2b. Determine the functional significance of MR1 SNPs. 2c. Determine the relationship of MR1 splice variant expression and the capacity of cells to present MR1 ligands to MR1T cells.