Intestinal CD4 T cell responses to dietary and microbial antigens

项目摘要 高度专门化的肠道免疫系统负责维持对来自 共生细菌和食物，同时提供对病原体的保护性免疫。对这一点的失调 临界平衡可导致炎症性肠病、食物过敏或增加对肠道的易感性 病原体。CD4+T细胞是肠道内环境稳定的关键因素，在抗原水平上微调反应 再认和功能分化。在肠上皮(IE)和下层固有层(LP)， 组织适应的促炎作用(即Th17，Th1)和调节性(Treg)和上皮内(CD8aa+CD4IEL)CD4+ T细胞协调免疫和对不同肠道刺激的耐受。然而，它仍有待定义。 TCR谱系及其特异性如何转化为LP和IEL对微生物抗原的反应功能。 此外，人们对饮食中抗原特异性肠道T细胞的特性知之甚少。口头的 耐受性，肠道内稳态的一种关键机制，口服抗原可导致局部 而系统对该抗原的耐受性，已知取决于Tregs。然而，多克隆的克隆动力学 T细胞在耐受状态下的反应尚不清楚。最后，在免疫或过敏的背景下， 特异地识别食物蛋白质的T细胞还没有确定。基于最近公布的数据 作为在当前资金周期中获得的初步数据，我们假设组织信号与 来自共生微生物和食物的TCR驱动信号稳定地指示肠道T细胞功能分化 状态，而感染或过敏原破坏正常T细胞反应会导致不适当的克隆 动态包括病理性T细胞的扩增。目标1将定义微生物区系或肠道刺激如何 病毒影响肠道CD4T细胞的TCR谱系和功能分化。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谱系和 肠道CD4T细胞的功能分化。我们将单细胞转录学与一种新的命运相结合- 选择性标记在不同微生物作用下被招募到肠道的外周T细胞的定位策略 饮食方面的挑战。一种新开发的LIPSTIC工具，允许标记肠上皮细胞(IECS) 将利用相互作用的细胞定义IEL招募/扩展的潜在机制，以响应 非我的刺激。最近产生的具有固定TCR VB链的小鼠品系，或携带微生物区系特异性的品系 TCRs与互补四聚体和生态学策略相结合，将被用来专门跟踪和 确定T细胞在肠道中迁移和分化过程中的识别特性。小说《超级四聚体》和 饮食操作，结合炎症挑战，将被用于定义食物抗原特异性T细胞 食物过敏或过敏时肠道中的CD4+T细胞对食物抗原的反应是如何改变的 感染环境。通过结合粘膜免疫学中的这些创新方法和概念，本提案 将有助于更好地确定非自身抗原刺激在肠道T细胞库和功能中的作用。

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.