Dissecting the molecular regulation of T cell localization and function within the Mycobacterium tuberculosis granuloma

项目总结/摘要 结核分枝杆菌（Mycobacterium tuberculosis，Mtb）感染是一个严重的全球性健康问题。尽管广泛免疫 与卡介苗和抗生素治疗的可用性，有1000万新病例和140万 每年死亡人数增加，强调需要改进治疗战略。CD 4 T细胞介导的免疫是 对于保护免受Mtb感染至关重要，并且受以下因素支配：1）CD 4 T细胞适当运输到不同的 Mtb感染的肺内的隔室，包括感染部位，和2）在这些隔室中的强大效应器功能 网站.我们已经发现了一种空间分辨的免疫抑制机制，通过这种机制， 在限制肉芽肿内T效应细胞的存在和功能方面起主导作用， 最大的影响直接邻近受感染的细胞。我们已经证明，T细胞TGFβ R信号传导的消融逆转了 这种抑制导致细菌负荷的降低。在这里，我们建议剖析机械的 这些观察的基础，并解决中心假设，即：不适当的定位CD 4 T细胞，结合肉芽肿核心范围内局部TGFβ激活的多效性抑制 有效免疫结核分枝杆菌肺部感染。为了解决这个假设，我们将使用一个易于处理的生理 小鼠超低剂量Mtb感染模型和先进的分析显微镜，然后确认学习的概念 在人类肺肉芽肿的小鼠中如下：1）我们将全面地表征个体如何 趋化因子受体有助于CD 4 T细胞定位、活化、功能和最终的感染结果。 这些发现将在人类肉芽肿中得到证实。2)我们还将描述TGFβ的激活是如何通过 单个细胞类型限制了局部CD 4 T细胞活化、功能和感染结果。这将得到验证 在死于活动性结核病的患者和死于结核病的无症状结核分枝杆菌感染者的肉芽肿中， 在抗生素时代，这是一种无与伦比的资源。这些研究还将提供以下信息： 存在于肺肉芽肿内的其他抑制途径，并为其提供了一个框架， 这些特性可以在未来的R 01应用中进行。因此，本提案将利用 我们的ULD Mtb小鼠模型和创新的成像工具，以了解T细胞如何运输到感染部位， 在这个空间中描述一个占主导地位的免疫抑制因子，这对 疫苗设计和宿主导向疗法。热尔恩博士的职业发展计划建立在使用 先进的成像研究肺部病原体与课程和实践培训，在先进的 免疫学、结核病发病机制、先进显微镜和实验室管理。一个K 08奖将允许博士。 热尔恩最大限度地利用SCRI和华盛顿大学广泛的科学资源，以实现科学独立， 推进他的职业目标，以了解决定免疫细胞运输和功能的因素，在不同的 组织微环境在结核分枝杆菌感染，以改善结核病治疗的最终目标。

PROJECT SUMMARY/ABSTRACT Mycobacterium tuberculosis (Mtb) infection is a major global health problem. Despite widespread immunization with Bacillus Calmette–Guérin and availability of antibiotic therapy, there are 10 million new cases and 1.4 million deaths annually, underscoring the need for improved treatment strategies. CD4 T cell-mediated immunity is critical for protection against Mtb infection, and is governed by 1) appropriate trafficking of CD4 T cells to distinct compartments within the Mtb-infected lung, including sites of infection, and 2) robust effector function at these sites. We have uncovered a spatially-resolved immunosuppressive mechanism by which localized TGFβ signal plays a dominant role in limiting the presence and function of T effector cells within the granuloma, with the greatest effect directly adjacent to infected cells. We have shown that ablation of T cell TGFβR-signaling reverses this suppression and results in reduced bacterial burdens. Here we propose to dissect the mechanistic underpinnings of these observations and address the central hypothesis that: Inappropriate localization of CD4 T cells, in combination with pleiotropic inhibition by localized TGFβ activation within the granuloma core limits effective immunity to Mtb pulmonary infection. To address this hypothesis, we will use a tractable yet physiologic murine ultra-low dose model of Mtb infection and advanced analytical microscopy, then confirm concepts learned in mice in human pulmonary granulomas as follows: 1) We will comprehensively characterize how individual chemokine receptors contribute to CD4 T cell localization, activation, function and ultimately, infection outcome. These findings will be corroborated in human granulomas. 2) We will also characterize how TGFβ activation by individual cell types limits localized CD4 T cell activation, function and infection outcome. This will be validated in granulomas from patients who die from active TB and those with asymptomatic Mtb infection who die from other causes, an unparalleled resource in the antibiotic era. These studies will also yield information about additional inhibitory pathways that are present within pulmonary granuloma and provide a framework for their characterization which can be pursued in future R01 applications. Thus, this proposal will leverage the strengths of our ULD Mtb mouse model and innovative imaging tools to understand how T cells traffic to infected sites and characterize a dominant immunosuppressive factor within this space, which has important implications for vaccine design and host-directed therapy. Dr. Gern’s career development plan builds on a background of using advanced imaging to study pulmonary pathogens with coursework and hands-on training in advanced immunology, Mtb pathogenesis, advanced microscopy, and laboratory management. A K08 award will allow Dr. Gern to make maximal use of SCRI and UW’s extensive scientific resources to achieve scientific independence, advancing his career goal to understand the factors dictating immune cell trafficking and function within different tissue microenvironments during Mtb infection, with the ultimate goal of improving tuberculosis treatment.