Regulation of CD8+ T Cell Homeostatis by IL-4

本研究拟探讨IL-4对T细胞稳态和免疫的调节作用。第四部分是对我国的社会保障制度进行研究 假设：1）IL-4刺激CD 8 + T细胞增殖; 2）IL-4也刺激非T细胞分化 转化为抑制活化的CD 8 + T细胞的调节细胞; 3）这两个过程的动力学差异 导致IL-4首先增强，然后抑制CD 8 + T细胞应答;和4）这些现象在以下方面是重要的： 健康和疾病中的CD 8 + T细胞稳态。这一假设基于体内小鼠研究， 结果表明：1）IL-4对正常的CD 8 + T细胞，尤其是记忆性CD 8 + T细胞的稳态是必需的 内稳态;和2）生理浓度的IL-4急性诱导CD 8 + T细胞通过一种免疫调节因子增殖。 部分Stat 6依赖性过程，但更缓慢地降低CD 8 + T细胞应答和细胞数量， 一个完全依赖Stat 6的过程抑制与一个扩大的，激活的 CD 11b + Ly 6 Ghi中性粒细胞群体，其他研究者认为其参与了灭活 和杀伤活化的CD 8 + T细胞。我们的假设在3个具体目标中得到解决。第一个评价 IL-4刺激T细胞活化和存活的信号传导需求。它将决定 IL-4激活Stat 6、Stat 5和PI-3 K，以实现IL-4的促有丝分裂和抗凋亡作用。它还将 研究为什么需要IL-4和IL-15来维持记忆性CD 8 + T细胞。第二个目标是 IL-4-调节细胞的活化。它将识别和表征由IL-4激活的脾细胞，以抑制 并杀死活化的CD 8 + T细胞;确定活化这些调节细胞所需的IL-4剂量; 对它们的活化很重要的信号通路;确定它们杀死活化T细胞的机制 细胞，并评估它们在IL-4抑制细胞毒性移植物抗宿主病的小鼠模型中的重要性 （GVHD）。第三个目标是评估内源性产生的IL-4和相关细胞因子IL-13的作用， 对健康和疾病中的CD 8 + T细胞稳态的影响。为了评估我们结果的普遍性， 目的是研究IL-4和IL-13对两种炎症小鼠模型中T细胞稳态的影响， 疾病：过敏性气道炎症（哮喘）和Omann综合征;以及三种 传染病：血吸虫病、疟疾和淋巴细胞性脉络丛脑膜炎病毒（LCMV）感染。每个 选择这些模型是因为它可以提供一些关于IL-4调节T细胞的独特信息， 细胞稳态和免疫，因为它也可以揭示IL-4调节的疾病相关性。 所提出的实验将在体内进行，并使用转基因小鼠、重组细胞因子、单克隆抗体、细胞因子受体和细胞因子受体。 抗体、细胞转移系统、CFSE标记、BrdU掺入、体内细胞因子产生的测定和 流式细胞术来验证我们的假设这些研究的结果应确定IL-4 促进或调节CD 8 + T细胞应答，并为IL-4和IL-4 用于扩增或抑制人的适应性或适应不良的CD 8 + T细胞应答的拮抗剂。

This proposal will study IL-4 regulation of T cell homeostasis and immunity. It will investigate the four part hypothesis that: 1) IL-4 stimulates CD8+ T cells to proliferate; 2) IL-4 also stimulates non-T cells to differentiate into regulatory cells that suppress activated CD8+ T cells; 3) differences in the kinetics of these two processes cause IL-4 to first enhance, then suppress CD8+ T cell responses; and 4) these phenomena are important in CD8+ T cell homeostasis in health and disease. This hypothesis is based on in vivo mouse studies that demonstrate that: 1) IL-4 is essential for normal CD8+ T cell homeostasis, especially memory CD8+ T cell homeostasis; and 2) physiological concentrations of IL-4 acutely induce CD8+ T cells to proliferate through a partially Stat6-dependent process but more slowly decrease CD8+ T cell responses and cell number through an entirely Stat6-dependent process. Suppression is associated with the appearance of an enlarged, activated population of CD11b+Ly6Ghi neutrophils, which have been implicated by other investigators in the inactivation and killing of activated CD8+ T cells. Our hypothesis is addressed in 3 specific aims. The first evaluates signaling requirements for IL-4 stimulation of T cell activation and survival. It will determine the importance of IL-4 activation of Stat6, Stat5, and PI-3K for the mitogenic and anti-apoptotic effects of IL-4. It will also investigate why both IL-4 and IL-15 are required to maintain memory CD8+ T cells. The second aim addresses IL-4-activation of regulatory cells. It will identify and characterize the spleen cells activated by IL-4 to suppress and kill activated CD8+ T cells; determine the dose of IL-4 required to activate these regulatory cells; identify the signaling pathways important for their activation; identify the mechanism(s) by which they kill activated T cells, and evaluate their importance in a mouse model in which IL-4 suppresses cytotoxic graft vs. host disease (GVHD). The third aim will evaluate the effects of endogenously-produced IL-4 and a related cytokine, IL-13, on CD8+ T cell homeostasis in health and disease. To allow evaluation of the generalizability of our results, this aim will examine the effects of IL-4 and IL-13 on T cell homeostatsis in mouse models of two inflammatory disorders: allergic airway inflammation (asthma) and Omann's syndrome; and mouse models of three infectious diseases: schistosomiasis, malaria, and lymphocytic choriomeningitis virus (LCMV) infection. Each of these models has been chosen because it can provide some unique information about IL-4 regulation of T cell homeostasis and immunity and because it also can shed light on the disease-relevance of IL-4 regulation. Proposed experiments will be performed in vivo and use transgenic mice, recombinant cytokines, monoclonal antibodies, cell transfer systems, CFSE labeling, BrdU incorporation, assays of in vivo cytokine production and flow cytometry to test our hypothesis. Results of these studies should identify the circumstances in which IL-4 promotes or regulates CD8+ T cell responses and provide a guide to the potential uses of IL-4 and IL-4 antagonists for amplifying or suppressing adaptive or maladaptive CD8+ T cell responses in humans.