Mucosal T Cells: Is Tolerance Floating on Lipid Rafts

描述（由申请方提供）：对正常肠道免疫调节的研究描述了肠道免疫系统的基本特性，该特性将其与其他外周和组织反应区分开来。 “生理性炎症”是肠中的免疫调节状态，其特征在于低反应性T淋巴细胞。 这种独特的，但分子上不确定的性质表明，主动耐受是粘膜免疫的重要组成部分。 我们认为，受调节的粘膜T细胞低反应性介导肠道免疫耐受，而不受调节的T细胞活化引发炎症性肠病（IBD）。 与通过CD 3途径激活的外周血T细胞（PBT）形成鲜明对比，肠道固有层T细胞（LPT）反应由使用CD 2受体的替代途径主导。 我们已经开发了一种体外模型，其中LPT可以在低反应（耐受）状态和反应（保护）激活状态之间切换。使用该模型，我们证明了在耐受性LPT中，通过CD 3受体复合物激活的两分钟内的膜近端信号传导显著降低，但不具有保护性。 我们还描述了富含胆固醇的膜微结构域，称为脂筏，不仅是质膜的结构组分，而且还定位蛋白质，用于启动PBT中的细胞内信号转导。 凭借我们在表征LPT、分离脂筏和描绘T细胞信号转导途径方面的专业知识，我们立即准备在分子水平上研究正常粘膜中的粘膜T细胞耐受性和IBD粘膜中的异常T细胞活化。 我们识别和表征LPT中脂筏成分异质性的能力将与分子，生物化学和免疫学技术相结合，以测试以下中心假设：肠T细胞上的脂筏异质性调节其信号传导，激活和功能，从而促进正常粘膜免疫耐受和慢性炎症。 我们的目标是a，如下：（1）评估脂筏异质性调节耐受性LPT中TCR信号传导复合物的正向和负向调节的结构机制。 (2)通过LPT中CD 2的相互作用，研究细胞骨架与脂筏的拓扑偶联。 (3)探讨第二信使Ras-MAPK通路在LPT脂筏中的生化调控作用。 (4)检查IBD粘膜中T细胞活化的脂筏调节的变化。 我们相信这种独特的方法将产生重要的新信息，肠道免疫耐受和炎症性肠病，通过检查调节膜近端事件在LPT信号转导和这些事件如何改变在炎症性肠病T细胞。

DESCRIPTION (provided by applicant): Investigations on the regulation of normal intestinal immunity have described a fundamental property of the intestinal immune system that distinguishes it from other peripheral and tissue responses. "Physiological inflammation" is a state of immune regulation in the intestine characterized by hypo-responsive T lymphocytes. This unique, but molecularly undefined property indicates that active tolerance is an essential component of mucosal immunity. We propose that regulated mucosal T cell hypo-responsiveness mediates intestinal immune tolerance, and that unregulated T cell activation initiates inflammatory bowel disease (IBD). In striking contrast to peripheral blood T cells (PBT), which are activated via the CD3 pathway, intestinal lamina propria T cell (LPT) responses are dominated by an alternate pathway that uses the CD2 receptor. We have developed an in vitro model in which LPT can toggle between a hypo-responsive (tolerant) state and a responsive (protective) state of activation. Using this model, we demonstrated that membrane proximal signaling within two minutes of activation through the CD3 receptor complex is markedly reduced in tolerant, but not protective LPT. We have also described that cholesterol-rich membrane micro-domains, called lipid rafts, are not only structural components of the plasma membrane, but also localize proteins for the initiation of intra-cellular signal transduction in PBT. With our expertise in characterizing LPT, isolating lipid rafts, and delineating signal transduction pathways in T cells, we are immediately poised to study mucosal T cell tolerance in the normal mucosa and aberrant T cell activation in the IBD mucosa at a molecular level. Our ability to identify and characterize heterogeneity among lipid raft constituents in LPT will be combined with molecular, biochemical, and immunological techniques to test the following central hypothesis: Lipid raft heterogeneity on intestinal T cells modulates their signaling, activation, and function, thereby contributing to both normal mucosal immune tolerance and chronic inflammation. Our aims are a, follows: (1) evaluate the structural mechanisms by which lipid raft heterogeneity modulates positive and negative regulation of the TCR signaling complex in tolerant LPT. (2) Investigate the topological coupling of the cytoskeleton to lipid rafts, via interactions through CD2 in LPT. (3) Explore the biochemical regulation of the second messenger Ras-MAPK pathway in lipid rafts from LPT. (4) Examine changes in lipid raft modulation of T cell activation from IBD mucosa. We believe this unique approach will generate important new information on intestinal immune tolerance and IBD, by examining the regulation of membrane proximal events in LPT signaling and how these events change in the IBD T cell