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

项目摘要(摘要) 好了！ 结核分枝杆菌(M.tb)在2017年造成了160多万人死亡，使其成为 是全球主要的传染病死亡原因。目前，牛分枝杆菌卡介苗(BCG)是 唯一获得许可的结核病疫苗。卡介苗可预防疾病的传播。 但在预防成人肺结核方面并不一致。因为成年人 肺结核具有高度传染性，卡介苗无法实现疫情的控制， 迫切需要新的疫苗。一系列来自人类和动物研究的证据表明 T细胞在增强结核分枝杆菌保护性免疫中的重要作用。然而，我们仍然不知道是哪一个 结核分枝杆菌抗原是提供保护作用的T细胞的靶标。这些信息对于开发新的 比卡介苗更有效的疫苗。传统上，T细胞是由外源多肽抗原激活的 与高度多态的主要组织相容性(MHC)分子结合。或者，分枝杆菌细胞壁 已有确凿证据表明，当脂质与抗原上的CD1蛋白结合时，可以激活人类T细胞- 呈现细胞。CD1系统已被证明在小鼠模型中介导保护性T细胞反应 自身免疫、癌症和传染病。然而，缺乏合适的动物模型阻碍了 CD1限制性T细胞在结核分枝杆菌发病机制中的作用识别CD1的工具- 直到最近，限制性T细胞也是不可用的。在过去的十年里，我们已经建立了富含脂肪的 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CD1转基因(HCD1Tg)小鼠模型，并表明T细胞 对分枝杆菌细胞壁的主要成分分枝杆菌酸具有特异性，对结核分枝杆菌具有保护性免疫。 挑战。最后，我们现在还在为非人类灵长类(NHP)结核病模型开发CD1四聚体。 这些初步数据确立了开发用于研究其作用的大小动物模型的可行性 CD1限制性T细胞在结核病发病机制中的作用在目标1中，我们将验证一套加载的人类CD1四聚体 用合成的脂类抗原检测CD1限制性T细胞的组织特异性表型和功能 分枝杆菌疫苗接种或感染hCD1Tg小鼠和NHP后。在目标2中，我们将探索卡介苗 通过不同途径(经皮、雾化或静脉注射)或原发感染结核分枝杆菌可诱导脂质代谢。 在hCD1Tg小鼠和NHP中提供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 HCD1Tg过继转移实验研究脂类抗原特异性T细胞是否具有保护性免疫作用 老鼠。到资助期结束时，我们将验证一套可供更广泛的人使用的工具 结核病研究社区，并讨论了是否应将脂质特异性T细胞视为与 全细胞分枝杆菌疫苗II/III期临床疗效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.