Mechanisms Controlling the Development and Function of Intestinal Effector Treg cells

项目摘要 控制肠道效应Treg细胞发育和功能的机制。的 称为炎性肠病（IBD）的一系列疾病的发病机制的特征在于： 免疫失调的肠道微生物群的组成部分。老鼠和人类的研究结果突出了一个关键的， 免疫调节细胞因子IL-10在维持肠道免疫稳态中的非冗余作用。 我们的实验室已经表明，Foxp 3+调节性T（Treg）细胞是绝大多数人中IL-10的主要来源。 肠，其中许多这些细胞共表达经典的“Th 17”转录因子，ROR β t-特别是 大肠（LI）。然而，IL-10仅由Treg细胞的一个亚群产生-定义为“效应”（e）Treg 细胞控制eTreg细胞发育的机制尚不完全清楚。此前提 应用程序，建立在最近的发现，和协同作用，两个PI（韦弗，哈顿）是， 迄今为止，IL-2和TNF超家族的信号通路之间未被认识到的相互作用具有中心的 在调节肠中eTreg细胞的发育和功能中的作用。具体来说，我们已经确定了 TNF受体超家族信号对TNFSF 15-TNFSF 25（TL 1A-DR 3）作为TNF受体的重要放大器， “中心”（c）Treg细胞向eTreg细胞的转变，并提出该途径在 通过多种机制校准Treg细胞程序的IL-2驱动的控制。我们假设TL 1A- DR 3通路在其调节IL-2受体（IL-2 R）信号传导以调节细胞大小和cTreg-1的过程中是非冗余的。 在稳态和炎症条件下Ll Treg细胞库的eTreg平衡。此外，我们 DR 3通过多种机制改变IL-2 R的输出以调节IL-10的发展， 产生eTreg细胞。我们提出eTreg细胞发育的主要驱动力是增加的STAT 3输出， IL-2 R，其通过DR 3的作用增强以：（i）增加IL-2 R的敏感性;和（ii）降低pSTAT 3 IL-2诱导的STAT 5/STAT 3比率。最后，我们建议其他TNFRSF DR 3成员有助于eTreg细胞在DR 3表达下降后的维持。我们通过以下方式来检验这一假设： 互补的，但不是相互依赖的，目标，利用：一种新的方法，用于产生稳定的，结肠炎治愈 Treg细胞离体;在原代T细胞中有效基因敲低的新方法;以及新的基因靶向 小鼠模型，以确定控制这些信号通路在控制 IL 10和eTreg程序的转录调控。成功实现这些目标将建立新的 生物学范例并提供新的治疗方法，通过该方法可以上调内源性IL-10 并增强eTreg细胞的分化和功能以治疗人IBD。

PROJECT SUMMARY Mechanisms Controlling the Development and Function of Intestinal Effector Treg Cells. The pathogenesis of a spectrum of disorders referred to as inflammatory bowel disease (IBD) is characterized by immune dysregulation to components of the enteric microbiota. Findings from mouse and man highlight a critical, non-redundant role for the immunoregulatory cytokine IL-10 in maintenance of intestinal immune homeostasis. Our labs have shown that Foxp3+ regulatory T (Treg) cells are, overwhelmingly, the major source of IL-10 in the intestines, where many of these cells co-express the canonical “Th17” transcription factor, RORt—particularly in large intestine (LI). However, IL-10 is only produced by a subset of Treg cells—defined as ‘effector’ (e)Treg cells. Mechanisms that control the development of eTreg cells are incompletely understood. The premise of this application, founded on recent discoveries from, and synergy between, the two PIs (Weaver, Hatton) is that heretofore unappreciated interplay between signaling pathways of the IL-2 and TNF superfamilies has a central role in regulating the development and function of eTreg cells in the intestines. Specifically, we have identified the TNF receptor superfamily signaling pair, TNFSF15-TNFRSF25 (TL1A-DR3), as an important amplifier of the transition of “central” (c)Treg cells into eTreg cells and propose that this pathway plays an important role in calibrating IL-2–driven control of the Treg cell program via multiple mechanisms. We hypothesize that the TL1A- DR3 pathway is non-redundant in its regulation of IL-2 receptor (IL-2R) signaling to modulate the size and cTreg– eTreg balance of the LI Treg cell pool both at homeostasis and under inflammatory conditions. Further, we posit that DR3 acts through multiple mechanisms to alter output of the IL-2R to regulate development of IL-10– producing eTreg cells. We propose that a major driver of eTreg cell development is increased STAT3 output of the IL-2R, which is enhanced by actions of DR3 to: (i) increase sensitivity of the IL-2R; and (ii) decrease pSTAT3 degradation, thereby altering the IL-2–induced STAT5/STAT3 ratio. Finally, we propose that other TNFRSF members contribute to eTreg cell maintenance after DR3 expression declines. We test this hypothesis through complementary, but not inter-dependent, Aims, leveraging: a novel method for generating stable, colitis-curing Treg cells ex vivo; new approaches for efficient gene knock-downs in primary T cells; and new gene-targeted mouse models to define mechanisms governing the convergence of these signaling pathways in controlling the transcriptional regulation of Il10 and the eTreg program. Successful completion of these Aims will establish new biological paradigms and inform novel therapeutic approaches by which endogenous IL-10 can be up-regulated and the differentiation and function of eTreg cells enhanced to treat human IBD.