Lipid Antigens for iNKT Cells in the Gut Microenvironment

项目摘要 肠道微生物区系被认为是影响免疫反应的中心因素。这项提案涉及 理解微生物如何调节人类健康有两个重要问题：1)微生物是什么？ 影响免疫的衍生分子？2)长期接触微生物产品如何改变 免疫细胞在当地环境中的表型？发现并表征所涉及的分子 在共生微生物和免疫系统之间的串扰中是朝着调节 人类-微生物关系的有益和有害潜力。 该项目的第一个主要方面(目标1和2)使用一系列生化方法来定义特定的 来自人类肠道微生物的生物活性微生物脂类激活不变自然杀伤T细胞(INKT)，a 识别特定脂类为抗原并协调免疫反应的特殊淋巴细胞亚群 在多个上下文中。尽管动物模型已经发现了iNKT细胞在免疫中的作用，但脂质 在大多数情况下，他们识别的抗原仍然未知。在这里，我们研究了两个人类共生体 产生iNKT细胞激活脂的微生物，这在肠道厌氧菌中是不常见的特征。要确定 激活iNKT细胞的特定分子脂质物种，我们将使用一种新开发的方法，即T细胞 受体陷阱，“以捕获抗原脂。一旦提纯，这些脂类将以质量为特征 光谱学，包括区分糖立体化学的新方法，这对 激活iNKT细胞的脂类活性。 该项目的第二个主要方面(目标3)建立在初步转录数据的基础上，以调查如何 在小鼠模型中，长期暴露于脂类抗原会影响肠道中iNKT细胞的表型。自iNKT以来 细胞在许多情况下协调免疫反应，并可能是有益的，也可能是有害的，变化到 它们在肠道中的表型可能会改变肠道感染、炎症性肠病、结肠 癌症，或食物过敏。为了了解肠道中的脂质如何调节iNKT细胞群，我们将使用两个 还原主义者模型，用含有不同水平iNKT细胞脂抗原的实验性饲料喂养小鼠， 或者用产生脂类抗原的微生物来定植无菌小鼠。在这些模型中，我们将表现出高性能 肠道iNKT细胞群体的深度表型。 总之，这些研究将确定来自人类肠道微生物区系两个重要成员的脂类抗原和 阐明了肠脂抗原塑造iNKT细胞群体的机制。

Project Summary The gut microbiota is recognized as a central factor influencing immune responses. This proposal addresses two important questions in understanding how microbes regulate human health: 1) What are the microbe- derived molecules that influence immunity? 2) How does chronic exposure to microbial products alters the phenotype of immune cells in their local environment? Discovering and characterizing the molecules involved in the crosstalk between symbiont microbes and the immune system is a fundamental step towards modulating both the beneficial and harmful potential of the human-microbe relationship. The first major aspect of this project (Aims 1 and 2) uses a series of biochemical approaches to define specific bioactive microbial lipids from human-derived gut microbes that activate invariant natural killer T (iNKT) cells, a specialized lymphocyte subset that recognizes specific lipids as antigens and orchestrates immune responses in multiple contexts. Although animal models have uncovered a role for iNKT cells in immunity, the lipid antigens that they recognize remain unknown in most situations. Here, we study two human symbiont microbes that produce iNKT cell-activating lipids, an uncommon feature among gut anaerobes. To identify the specific molecular lipid species that activate iNKT cells, we will use a newly-developed method, the “T cell receptor trap,” to capture antigenic lipids. Once purified, these lipids will be characterized by mass spectrometry, including new methods that distinguish sugar stereochemistry, which is of central importance to the activity of lipids that activate iNKT cells. The second major aspect of this project (Aim 3) builds on preliminary transcriptomic data to investigate how chronic exposure to lipid antigens affects the phenotype of iNKT cells in the gut in a mouse model. Since iNKT cells orchestrate immune responses in many situations, and can be either beneficial and harmful, changes to their phenotype in the gut is likely to alter the course of enteral infection, inflammatory bowel disease, colon cancer, or food allergy. To understand how lipids in the gut regulate iNKT cell populations, we will use two reductionist models, feeding mice with experimental diets containing different levels of iNKT cell lipid antigens, or colonization of germ-free mice with lipid antigen-producing microbes. In these models, we will perform high- depth phenotyping of the gut iNKT cell populations. Together, these studies will define lipid antigens from two important members of the human gut microbiota and shed light on the mechanisms by which gut lipid antigens shape iNKT cell populations.