Intestinal CD4 T cell responses to dietary and microbial antigens

项目概要 高度专业化的肠道免疫系统负责维持对无害刺激的耐受性 共生细菌和食物，同时提供针对病原体的保护性免疫力。这方面的失调 临界平衡可能导致炎症性肠病、食物过敏或对肠道的易感性增加 病原体。 CD4 T 细胞是肠道稳态的关键参与者，可在抗原水平上微调反应 识别和功能分化。在肠上皮 (IE) 和下面的固有层 (LP) 中， 组织适应促炎性（即 Th17、Th1）和调节性（Treg）和上皮内（CD8aa CD4IEL）CD4 T 细胞协调免疫和对多种肠道刺激的耐受性。尽管如此，仍有待定义 TCR 库及其特异性如何转化为 LP 和 IEL 响应微生物抗原的功能。 此外，人们对饮食抗原特异性肠道 T 细胞的特性知之甚少。口服 耐受性，肠道稳态的一个关键机制，口服抗原会导致局部 众所周知，对该抗原的全身耐受性取决于 Tregs。然而，多克隆的克隆动力学 T 细胞在耐受情况下的反应仍不清楚。最后，在免疫或过敏的情况下， 特异性识别食物蛋白的 T 细胞尚未确定。也基于最近发布的数据 作为当前融资周期中获得的初步数据，我们假设组织线索与 来自共生微生物和食物的 TCR 驱动信号决定肠道 T 细胞功能稳定分化 状态，而感染或过敏原对正常 T 细胞反应的破坏会导致不适当的克隆 动力学，包括病理性 T 细胞的扩增。目标 1 将定义如何通过微生物群或肠道刺激 病毒影响 TCR 库和肠道 CD4 T 细胞的功能分化。目标 2 将描述 饮食抗原在耐受性、肠道感染或食物过敏中的作用，影响 TCR 库和 肠道CD4 T细胞的功能分化。我们将单细胞转录组学与一种新颖的命运相结合 绘制策略以选择性地标记在各种微生物作用下招募到肠道的外周 T 细胞 和饮食挑战。最近开发的 LIPSTIC 工具，允许肠上皮细胞 (IEC) 标记 相互作用的细胞将被用来定义 IEL 招募/扩展的潜在机制，以响应 非自身刺激。最近生成的具有固定 TCR Vb 链或携带微生物群特异性的小鼠品系 TCR 与互补的四聚体和限菌策略相结合，将用于专门跟踪和 定义肠道中 T 细胞迁移和分化过程中的识别特性。新颖的“超级四聚体”和 饮食控制与炎症挑战相结合将用于定义食物抗原特异性 T 细胞 稳态期间以及肠道 CD4 T 细胞对饮食抗原的反应如何在食物过敏或 感染背景。通过结合粘膜免疫学中的这些创新方法和概念，该提案 将有助于更好地确定非自身抗原刺激在 T 细胞库和肠道功能中的作用。

Project Summary The highly specialized intestinal immune system is charged with maintaining tolerance to harmless stimuli from commensal bacteria and food, while providing protective immunity against pathogens. Dysregulation of this critical balance can lead to inflammatory bowel disease, food allergy, or increased susceptibility to enteric pathogens. CD4+ T cells are key players in intestinal homeostasis, finely tuning responses at the level of antigen recognition and functional differentiation. In the intestinal epithelium (IE) and underlying lamina propria (LP), tissue adapted pro-inflammatory (ie. Th17, Th1) and regulatory (Treg) and intraepithelial (CD8aa+ CD4IEL) CD4+ T cells coordinate immunity and tolerance to diverse intestinal stimuli. Nevertheless, it remains to be defined how TCR repertoire and its specificity translate to function of both LP and IELs in response to microbial antigens. Additionally, very little is known about the characteristics of dietary antigen-specific intestinal T cells. Oral tolerance, a critical mechanism of gut homeostasis whereby oral administration of antigen results in both local and systemic tolerance to that antigen, is known to depend on Tregs. However, the clonal dynamics of polyclonal T cell responses in the setting of tolerance remain unclear. Finally, outside the context of immunization or allergy, T cells that specifically recognize food protein have yet to be identified. Based on data recently published as well as preliminary data obtained during the current funding cycle, we hypothesize that tissue cues combined with TCR-driven signals from commensal microbes and food dictate intestinal T cell functional differentiation in steady state, while disruption of normal T cell responses by infections or allergens results in inappropriate clonal dynamics including expansion of pathological T cells. Aim 1 will define how stimulation by microbiota or enteric viruses impact TCR repertoire and functional differentiation of intestinal CD4 T cells. Aim 2 will characterize the role of dietary antigens in the context of tolerance, enteric infections, or food allergy, affect TCR repertoire and functional differentiation of intestinal CD4 T cells. We combine single cell transcriptomics with a novel fate- mapping strategy to selectively label peripheral T cells that are recruited to the intestine under various microbial and dietary challenges. A recently developed LIPSTIC tool that allows intestinal epithelial cells (IECs) labeling of interacting cells will be utilized to define potential mechanisms of IEL recruitment/expansion in response to nonself stimuli. Recently generated murine strains with fixed TCR Vb chain, or that carry microbiota-specific TCRs, combined with complementary tetramer and gnotobiotic strategies will be used to specifically track and define recognition properties during T cell migration and differentiation in the gut. Novel “super-tetramer” and dietary manipulations, combined with inflammatory challenges will be used to define food antigen-specific T cells during steady state and how intestinal CD4+ T cell responses to dietary antigen are altered in a food allergic or infection context. By combining these innovative approaches and concepts in mucosal immunology, this proposal will help better defining the role of nonself antigen stimulation in T cell repertoire and function in the intestine.