The human lung and lung-draining lymph node response to Mycobacterium tuberculosis

项目概要/摘要 这个项目的重点是获得概念和机制的见解免疫介质，有助于 人肺和肺结核保护性免疫的建立 引流淋巴结虽然结核病（TB）通常表现为肺部疾病，但胸部淋巴结 淋巴结是肺外Mtb感染的最常见部位。结核杆菌可以在淋巴结中被重新激活， 导致肉芽肿的形成和Mtb向肺和其它器官的传播。然而，淋巴 人类对结核分枝杆菌的淋巴结反应仍未得到充分研究。结核病发病机制的一个关键特征是肉芽肿 形成;这些结构内的微调免疫反应决定了局部感染的结果。在这里， 我们的目的是进行比较评估的免疫（特别是T细胞）反应，在人类 肺和淋巴结肉芽肿，成功和不成功消除结核分枝杆菌。完成 因此，我们建议用肉芽肿反应的组织学证据来表征标本，（a）显示 抗酸杆菌（AFB）染色阴性，但PCR检测TB-DNA阳性（反映 在肉芽肿水平的杀菌免疫或成功的免疫应答），和（B）显示阳性AF B染色 （表示主机尝试不成功）。在动物模型中的研究表明，T细胞在 控制结核病的临床进程，以及对结核分枝杆菌抗原的T细胞应答在胸淋巴中启动 而不是肺部因此，首先，我们将测试假设，即绝育免疫和 不成功的应答源于特异性效应T细胞表型和功能的差异， 肉芽肿中的空间组织。事实上，我们的初步数据表明，特异性CD 8 + T细胞应答 与肉芽肿水平的Mtb清除相关。我们的下一个目标是利用这些知识来指导选择 合适的抗原通过疫苗接种重新引发这种反应。为了达到这个目的，我们要建立组织- 来自淋巴结的模拟类器官，其是免疫接种后细胞免疫的分期基础。 我们将检验这一假设，即这些在肉芽肿中自然引发的保护性T细胞反应， 在来自TB初治供体的淋巴结类器官中由特异性Mtb（非BCG）抗原诱导。最后我们将 采用T细胞受体测序和机器学习算法的组合来识别精确的 保护性表位总的来说，我们希望我们的结果能对决定因素产生重要的新见解 结核病的免疫防御，确定新的结核病疫苗的候选人，并为管理创造机会， 结核病的全球负担。

Project summary/Abstract This project is focused on gaining conceptual and mechanistic insights into immune mediators that contribute to the development of protective immunity against Mycobacterium tuberculosis (Mtb) in human lung and lung- draining lymph nodes. Although tuberculosis (TB) typically manifests as a pulmonary disease, thoracic lymph nodes are the most common sites of extrapulmonary Mtb infection. Mtb can be reactivated in lymph nodes, leading to the formation of granulomas and Mtb dissemination to the lungs and other organs. Yet, the lymph node response to Mtb in humans remains understudied. A key feature of Mtb pathogenesis is granuloma formation; finely tuned immune responses within these structures determine localized infection outcomes. Here, we aim to perform a comparative assessment of the immune (specifically, T cell) responses within human pulmonary and lymph node granulomas that are successful and unsuccessful in eliminating Mtb. To accomplish this, we propose to characterize specimens with histological evidence of a granulomatous reaction that (a) show negative Acid-Fast-Bacilli (AFB) stain but test positive for the presence of TB-DNA by PCR (reflective of sterilizing immunity or a successful immune response at the granuloma level), and (b) show positive AFB stain (representing an unsuccessful host effort). Studies in animal models have shown that T cells are important in controlling the clinical course of TB and that the T cell response to Mtb antigens is initiated in thoracic lymph nodes and not the lungs. Thus, first, we will test the hypothesis that differences between sterilizing immunity and unsuccessful responses stem from differences in specific effector T cell phenotypes and functions, and their spatial organization in the granulomas. Indeed, our preliminary data show that specific CD8+ T cell responses associate with Mtb clearance at the granuloma level. Our next goal is to use this knowledge to guide the selection of appropriate antigens to re-elicit this response through vaccination. To accomplish this, we will establish tissue- mimetic organoids from lymph nodes, which are the staging grounds for cellular immunity following immunization. We will test the hypothesis that these protective T cell responses that are naturally elicited in granulomas can be induced in lymph node organoids from TB-naïve donors by specific Mtb (not BCG) antigens. Finally, we will employ a combination of T cell receptor sequencing and machine-learning algorithms to identify the precise protective epitopes. Collectively, we expect our results to generate important new insight into the determinants of immune defense in TB, identify candidates for new TB vaccines, and create opportunities for the management of the global burden of tuberculosis.