INTESTINAL REGULATION OF ThPOK EXPRESSION AND CD4 HELPER T CELL FUNCTION

描述(申请人提供)：庞大的肠道相关免疫系统，占体内大多数淋巴细胞和抗体，必须抑制病原体的渗透和传播，同时控制可能危及粘膜上皮屏障完整性的过度或不必要的免疫反应。虽然CD4辅助T细胞对产生有效的免疫反应至关重要，但不受控制的CD4辅助T细胞可能对生物体构成威胁。CD8细胞毒性T细胞的命运取决于Run家族的转录因子Runx3，而CD8细胞毒性T细胞的命运则取决于Run家族的转录因子Runx3。我们最近发现了一种肠道特异性和高度可塑性的过程，当迁移到肠道上皮时，驱动CD4T细胞中ThPOK的下调。成熟的CD4T细胞失去ThPOK伴随着T细胞辅助功能的抑制，特别是Th17表型的抑制，以及Runx3和细胞毒相关分子的上调。人们最感兴趣的是挑战调节辅助T细胞稳定性的因素以及这些转录因子在成熟的CD4辅助T细胞中调节的功能后果。我们假设，在从外周到肠腔的迁移过程中，活化的CD4T细胞暴露在几个可能协调这一过程的环境因素中。本研究将使用新的转基因小鼠品系和无菌动物来研究肠源性因子包括转化生长因子、维甲酸和共生菌在调节CD4辅助T细胞功能中的作用。此外，与表观遗传学相关的生物信息学 技术将被用来定义驱动ThPOK和Runx3调制的上游机制，以识别参与辅助T细胞功能的下游靶点。最后，将使用感染和炎症性肠病(IBD)的模型来研究辅助T细胞这种不可预测的可塑性的功能后果。活体实验将确定肠道中ThPOK和Runx3表达的调节如何影响CD4T细胞引起或控制炎症的能力。虽然伴随而来的ThPOK的丧失和Runx3的获得可能有利于避免过度炎症和组织破坏，但如果是特定的，它可能是有害的。细胞因子是免疫保护所必需的。这里提出的研究将直接解决肠道环境诱导的CD4T细胞外周可塑性在IBD发病机制和肠道感染控制中的功能意义。这项建议完全使用了新的概念，解剖了一条将辅助T细胞转移到肠道中的细胞毒性T细胞的生理途径，以解决CD4T细胞辅助分化和功能的生物学基础。因此，通过本研究获得的知识将扩大我们对获得性免疫的发展和调控的理解，为宿主与微生物的相互作用和疫苗接种策略提供有价值的信息。

DESCRIPTION (provided by applicant): The vast gut-associated immune system, which accounts for most of the lymphocytes and antibodies in the body, must inhibit penetration and spreading of pathogens while controlling excessive or unnecessary immune responses that could jeopardize the integrity of the mucosal epithelial barrier. Although CD4 helper T cells are crucial for the generation of efficient immune responses, uncontrolled CD4 helper T cells can pose a threat to an organism. The CD4 fate is initially induced in thymocytes and continuously maintained in mature T cells by the zinc finger transcription factor, ThPOK, while CD8 cytotoxic T cell fate depends on the transcription factor of Runt family, Runx3. We recently found a gut specific and highly plastic process that drives the downregulation of ThPOK in CD4 T cells upon migration to the intestinal epithelium. The loss of ThPOK by mature CD4 T cells is accompanied by suppression of T cell helper function, particularly the Th17 phenotype, and upregulation of Runx3 and cytotoxic-related molecules. It is of utmost interest to defie factors that regulate the stability of helper T cells and functional consequences of modulation of these transcription factors in mature CD4 helper T cells. We hypothesize that during migration from the periphery to the intestinal compartment, activated CD4 T cells are exposed to several environmental factors that may orchestrate this process. This study will use novel genetically modified mouse strains and germ-free animals to investigate the role of intestinal-derived factors including TGF-ß, retinoic acid and commensal bacteria, in the modulation of CD4 helper T function. Additionally, bioinformatics associated with epigenetics techniques will be used to define upstream mechanisms that drive ThPOK and Runx3 modulation as to identify downstream targets involved in helper T cell function. Finally, the functional consequences of this unpredicted plasticity of helper T cells will be studied using models of infection and inflammatory bowel diseases (IBD). In vivo experiments will determine how the modulation of ThPOK and Runx3 expression in the intestine influences the capacity of CD4 T cells to cause or control inflammation. While the concomitant loss of ThPOK and acquisition of Runx3 may be beneficial to avoid excessive inflammation and tissue destruction, it may be detrimental when specific. The cytokines are required for immune protection. The studies proposed here will directly address functional implications of the peripheral plasticity of CD4 T cells, induced by intestinal milieu, in the IBD pathogenesis and in the control of intestinal infections. This proposal uses exclusively novel concepts, dissecting a physiological pathway that shifts helper T cells towards cytotoxic T cells in the intestine, to address the biology behin CD4 T cells helper differentiation and function. Therefore, by the knowledge gained from this study will expand our understanding of the development and modulation of the adaptive immunity, providing valuable information regarding host-microbial interactions and vaccination strategies.