The Role of Lipid-specific T cells in Mediating Protection Against M. tuberculosis

项目概要（摘要） ! 结核分枝杆菌（M. tb）在2017年造成160多万人死亡，使其成为全球最严重的结核病。 是世界范围内最主要的传染性死亡原因目前，牛分枝杆菌卡介苗（BCG）是 唯一获得许可的肺结核疫苗卡介苗可预防疾病的传播 在儿童中，但在预防成人肺结核的发展方面不一致。自从成年人 肺结核具有高度传染性，用卡介苗无法控制流行， 迫切需要新的疫苗。人类和动物研究的大量证据表明， T细胞在赋予对M.tb的保护性免疫中的至关重要性。然而，我们仍然不知道 结核分枝杆菌抗原被赋予保护作用的T细胞靶向。这些信息对于开发新的 比BCG更有效的疫苗。传统上，T细胞被外源肽抗原激活， 与高度多态性的主要组织相容性（MHC）分子结合。或者，分枝杆菌细胞壁 脂质已经明确显示当与抗原上的CD1蛋白结合时激活人T细胞， 呈递细胞已经显示CD 1系统在免疫缺陷小鼠模型中介导保护性T细胞应答。 自身免疫、癌症和传染病。然而，由于缺乏合适的动物模型， 研究CD1限制性T细胞在结核病发病机制中的重要性。识别CD1的工具- 限制性T细胞直到最近也是不可用的。在过去的十年里，我们已经建立了脂质加载 CD1四聚体作为研究人类CD1限制性T细胞表型和功能的工具。我们有 还开发并验证了人源化CD 1转基因（hCD 1Tg）小鼠模型，并显示T细胞 对分枝杆菌细胞壁的主要成分分枝菌酸具有特异性，赋予对结核分枝杆菌的保护性免疫力 挑战.最后，我们现在还在开发用于结核病非人灵长类动物（NHP）模型的CD1四聚体。 这些初步数据建立了发展小型和大型动物模型的可行性，用于研究 CD1限制性T细胞在结核病发病机制中的作用。在目标1中，我们将验证一套人CD 1四聚体加载 与合成的脂质抗原，并确定组织特异性表型和功能的CD1-限制性T细胞 在分枝杆菌疫苗接种或hCD 1Tg小鼠和NHP感染后。在目标2中，我们将探讨BCG是否 通过不同途径（皮肤、气雾剂或静脉内）给药或原发性结核分枝杆菌感染诱导脂质- 在hCD1Tg小鼠和NHP中赋予对结核分枝杆菌攻击的保护性免疫的特异性T细胞。我们还将研究 在hCD1Tg中使用过继转移实验来确定脂质抗原特异性T细胞是否赋予保护性免疫 小鼠到融资期结束时，我们将验证一套工具， 结核病研究界和解决是否脂质特异性T细胞应被认为是一个相关的 全细胞分枝杆菌疫苗II/III期临床有效性研究中的保护性免疫。

PROJECT SUMMARY (ABSTRACT) ! Mycobacterium tuberculosis (M.tb) was responsible for more than 1.6 million deaths in 2017, making it a leading infectious cause of death worldwide. Currently, Mycobacterium bovis bacille Calmette-Guérin (BCG) is the only licensed vaccine for tuberculosis. BCG provides protection against disseminated forms of the disease in children but is inconsistent in preventing the development of pulmonary tuberculosis in adults. Since adults with pulmonary tuberculosis are highly infectious, control of the epidemic will not be achieved with BCG, and new vaccines are urgently needed. A number of lines of evidence from human and animal studies have revealed the critical importance of T cells in conferring protective immunity to M.tb. However, we still do not know which M.tb antigens are targeted by the T cells that confer protection. This information is critical to developing new vaccines that are more effective than BCG. Classically, T cells are activated by foreign peptide antigens that are bound to highly polymorphic major histocompatibility (MHC) molecules. Alternatively, mycobacterial cell wall lipids have conclusively been shown to activate human T cells when bound to CD1 proteins on antigen- presenting cells. The CD1 system has been shown to mediate protective T-cell responses in mouse models of autoimmunity, cancer, and infectious diseases. However, the lack of an appropriate animal model has impeded research into the importance of CD1-restricted T cells in the pathogenesis of M.tb. Tools to identify CD1- restricted T cells were also unavailable until recently. Over the last ten years, we have established lipid-loaded CD1 tetramers as tools to study the phenotypes and functions of CD1-restricted T cells in humans. We have also developed and validated a humanized CD1 transgenic (hCD1Tg) mouse model and shown that T-cells specific for mycolic acid, a major constituent of the mycobacterial cell wall, confer protective immunity to M.tb challenge. Finally, we are now also developing CD1 tetramers for non-human primate (NHP) models of TB. These preliminary data establish the feasibility of developing small and large animal models for studying the role of CD1-restricted T cells in TB pathogenesis. In Aim 1, we will validate a suite of human CD1 tetramers loaded with synthetic lipid antigens and determine the tissue-specific phenotypes and functions of CD1-restricted T cells after mycobacterial vaccination or infection of hCD1Tg mice and NHP. In Aim 2, we will explore whether BCG administered by different routes (cutaneous, aerosol, or intravenous) or primary M.tb infection induces lipid- specific T cells that confer protective immunity to M.tb challenge in hCD1Tg mice and NHP. We will also study whether lipid antigen-specific T cells confer protective immunity using adoptive transfer experiments in hCD1Tg mice. By the end of the funding period, we will have validated a set of tools that will be available to the broader TB research community and addressed whether lipid-specific T cells should be considered a correlate of protective immunity in Phase II/III clinical efficacy studies of whole cell mycobacterial vaccines.