MHC-Ib restricted T cell responses against Listeria monocytogenes

描述（由申请方提供）：1单核细胞增生李斯特菌（Lm）是一种B类优先病原体，可引起食源性疾病暴发，发病率和死亡率较高。为了实现针对Lm的杀菌免疫，CD 8 + T细胞必须识别与感染细胞表面上的MHC-I蛋白结合的抗原，这是导致T细胞活化和获得保护性效应子功能的事件。经典的MHC-I蛋白（MHC-Ia）已经研究了60多年，然而，对于大多数非经典的MHC-I蛋白7（MHC-Ib）的研究相对较少。我们建立了Lm感染的MHC-Ia缺陷小鼠模型，以研究8种MHC-Ib限制性T细胞在细胞内细菌病原体清除中的作用。我们的中心假设是Lm免疫小鼠含有识别新型MHC-Ib 10蛋白的记忆性CD 8 + T细胞，并且这些T细胞在继发性Lm感染的清除中发挥重要作用。11在初步研究中，我们发现在Lm感染期间，识别12种新型（非M3）MHC-Ib蛋白背景下的抗原的CD 8 + T细胞被激活。我们已经确定了9个13鼠MHC-Ib基因作为可能的候选人表达的蛋白质，可以作为抗原14在感染过程中的呈递分子。在本申请中，我们提出：1）开发一组15个用9个候选MHC-Ib基因中的每一个转染的人巨噬细胞样细胞，和2）16使用MHC-Ib转染子来确定在Lm感染期间有多少不同的MHC-Ib蛋白能够将抗原呈递给T细胞。这些研究将有助于确定MHC-Ib限制性T细胞在抗Lm的保护性免疫应答中的作用，并可能有助于识别所有细胞内细菌病原体的新类型抗原。由于大多数MHC-Ib蛋白是非多态性的，因此与MHC-Ib蛋白结合的抗原很可能被给定群体中的大多数（如果不是全部）个体识别。这使得MHC-Ib 22抗原成为特别有吸引力的候选物，用于包含在设计用于防止细胞内细菌病原体感染的疫苗中。公共卫生相关性：在试图设计疫苗以保护免受可以在宿主细胞内存活的细菌感染时面临的一个重要障碍是识别所有个体都能识别的抗原，无论其血型如何（MHC单倍型）。在这项研究中，我们将表征识别与MHC-Ib蛋白结合的单核细胞增生李斯特菌抗原的T细胞亚群，MHC-Ib蛋白是一类在小鼠和人类中均为非多态性的蛋白质（在个体之间表现出很少的变化）。这些研究有可能导致新的治疗策略，以防止各种细胞内细菌的感染，包括流行的人类病原体，如结核分枝杆菌和沙眼衣原体。

DESCRIPTION (provided by applicant): 1 Listeria monocytogenes (Lm) is a category B priority pathogen that causes outbreaks of 2 foodborne illness with a high incidence of morbidity and mortality. To achieve sterilizing 3 immunity against Lm, CD8+ T cells must recognize antigens bound to MHC-I proteins on the 4 surface of infected cells, an event that results in activation of the T cells and acquisition of 5 protective effector functions. Classical MHC-I proteins (MHC-Ia) have been studied for 6 decades, however, comparatively little is known about most of the non-classical MHC-I proteins 7 (MHC-Ib). We developed a MHC-Ia deficient mouse model of Lm infection to study the role of 8 MHC-Ib restricted T cells in the clearance of intracellular bacterial pathogens. Our central 9 hypothesis is that Lm-immune mice contain memory CD8+ T cells that recognize novel MHC-Ib 10 proteins, and that these T cells play a significant role in the clearance of secondary Lm infection. 11 In preliminary studies, we showed that CD8+ T cells that recognize antigen in the context of a 12 novel (not M3) MHC-Ib protein are activated during Lm infection. We have identified nine 13 murine MHC-Ib genes as likely candidates to express proteins that could serve as antigen 14 presenting molecules during infection. In this application, we propose to: 1) develop a panel of 15 human macrophage-like cells transfected with each of the nine candidate MHC-Ib genes and 2) 16 use the MHC-Ib transfectants to determine how many different MHC-Ib proteins are capable of 17 presenting antigen to T cells during Lm infection. These studies will help to define the role of 18 MHC-Ib restricted T cells in protective immune responses against Lm and may facilitate the 19 identification of new classes of antigens for all intracellular bacterial pathogens. Since most 20 MHC-Ib proteins are non-polymorphic, antigens that bind to MHC-Ib proteins are likely to be 21 recognized by most, if not all of the individuals in a given population. This makes MHC-Ib 22 antigens particularly attractive candidates for inclusion in vaccines designed to protect against 23 infection with intracellular bacterial pathogens. PUBLIC HEALTH RELEVANCE: One of the significant hurdles faced in trying to design vaccines to protect against infection with bacteria that can survive inside host cells is the identification of antigens that will be recognized by all individuals, regardless of their blood type (MHC haplotype). In this study, we will characterize a subset of T cells that recognize antigens derived from Listeria monocytogenes bound to MHC-Ib proteins, a class of proteins that is non- polymorphic (displays little variation among individuals) in both mice and humans. These studies have the potential to lead to new therapeutic strategies to protect against infections with a variety of intracellular bacteria, including prevalent human pathogens such as Mycobacteria tuberculosis and Chlamydia trachomatis.