Mtb uptake and antigen presentation in human lung epithelial cells

描述(由申请人提供)： 结核病仍然是全世界传染病发病率和死亡率的重要原因，也是武装部队特别关切的问题。引起结核病的微生物--结核分枝杆菌(Mtb)是一种细胞内病原体。对免疫系统识别细胞内感染的这些机制的改进定义为改进疫苗和诊断提供了直接应用。在这项提案中，我们将定义人类肺上皮细胞摄取Mtb的机制，以及Mtb抗原在MHC I类分子MR1的背景下被处理并呈递给肺内常驻的CD8+T细胞(称为MAIT细胞)的途径。虽然肺上皮细胞是抵御结核分枝杆菌感染的第一道防线，但对上皮细胞摄取和提呈先天T细胞的机制知之甚少。提高我们对这种相互作用的理解将是合理设计更好的疫苗以服务于VA患者任务的关键。为了确定人肺上皮细胞被摄取的机制，我们将对体外培养的人肺上皮细胞中的结核分枝杆菌隔室进行详细的分析，涉及已知与摄取、囊泡运输以及抗原处理和呈递相关的蛋白质。为了确定上皮细胞Mtb小室在MR1抗原提呈中所起的作用，我们将对MR1的细胞定位、与Mtb小室的关联以及抗原处理和递送途径进行详细的分析。我们的假设是，Mtb被上皮细胞吸收进入不同于专业抗原提呈细胞吞噬小体的隔室，而抗原在MR1上的运输和提呈是启动和维持Mtb特异性粘膜免疫的必要步骤。

DESCRIPTION (provided by applicant): Tuberculosis remains an important cause of infectious disease morbidity and mortality worldwide, and is a problem of particular concern to those in the armed forces. The organism that causes tuberculosis, Mycobacterium tuberculosis (Mtb), is an intracellular pathogen. Improved definition of those mechanisms by which the immune system recognizes intracellular infection provides direct application to improved vaccines and diagnostics. In this proposal, we will define the mechanisms by which human lung epithelial cells take up Mtb and the pathways by which Mtb antigens are processed and presented in the context of the MHC Class I molecule, MR1, to lung resident CD8+ T cells known as MAIT cells (mucosal-associated invariant T cells). Although the lung epithelium is the first line of defense against infection with Mtb, very little is known about the mechanisms of uptake and antigen presentation by epithelial cells to innate T cells. Improving our understanding of this interaction will be critical to rational design of better vaccines to serve the VA patient mission. To define the mechanisms by which human lung epithelial cells are taken up, we will perform a detailed analysis of the Mtb compartment in human epithelial cells in vitro, with regard to proteins known to be associated with uptake, vesicular trafficking, and antigen processing and presentation. To characterize the role that the epithelial cell Mtb compartment plays in MR1 antigen presentation, we will perform a detailed analysis of MR1 with regard to its cellular localization, association with the Mtb compartment, and antigen processing and presentation pathways. Our hypothesis is that Mtb is taken up by epithelial cells into compartments that are distinct from phagosomes of professional antigen presenting cells, and that trafficking of and presentation of antigen on MR1 are requisite steps in initiation and maintenance of Mtb-specific mucosal immunity.