Dissecting the intestinal niche for regulatory T cells

1.目的：炎症性肠病（Inflammatory bowel diseases，IBD），包括克罗恩病（Crohns Disease）和溃疡性结肠炎（Ulcerative Colitis，UC），是近年来出现的一种肠道疾病。 遗传易感宿主，当肠上皮缺陷和对 寄生虫导致CD 4 + T细胞的过度活化和组织损伤。IBD也与 伴随着调节途径的丧失，包括调节性T细胞（T细胞）中的缺陷。Foxp 3的一个子集， 阳性CD 4 + T细胞是肠道耐受的核心;它们预防IBD疾病的发展， 抑制感染期间的炎症。在本申请中，我们试图理解 在健康和炎症期间维持肠道张力。调节性T细胞包括两种发育性T细胞， 不同的亚群：胸腺衍生的（tTreg或天然的（nTreg）和外周衍生的（pTreg）， 从传统的幼稚的CD 4 + T细胞。人类和小鼠的肠道含有这两种谱系的细胞， 必须保持宽容。Foxp 3缺陷型IPEX患者缺乏天然THBE， 婴儿肠炎。另外，控制外周分化的基因组区域的缺失也会导致细胞凋亡。 导致肠道炎症因此，鼠和人的研究都证明了对两者的要求。 维持肠道耐受性。没有数据定义不同的机械或 两个人群的解剖学要求。 在缺乏外周TCR-MHCII相互作用的小鼠中检查Treg定位和表型 和外周转化T细胞（pT细胞）。胸腺产生的nTdR进入小肠板层 在不存在MHCII的情况下，使用propria（siLP）填充隔室。完整组织的成像显示， siLP有两个不同的解剖位置：单独定位在siLP绒毛内或聚集在 类似于孤立淋巴滤泡（ILF）的有组织结构。我们的数据表明，一个子集的TdR 优先定位于ILF;这种关联在感染期间改变。此外，nT细胞和pT细胞 尽管对共刺激信号有不同的要求，但它们占据了重叠的小生境。因此，我们提出 假设1。胸腺源性和外周性Tactin-derived占据不同的生理生态位， 小肠和2个ILF为炎症期间可延展的THP提供了一个小生境。 2.研究设计：在我们的第一个目标中，我们将利用小鼠模型和健康的人体组织来确定， ILF是维持siLP T细胞所必需的，定义了ILF中存在的共刺激信号， 然后询问ILF是否特异性地吸引和维持胸腺TdR而不是pTdR。的多项研究 老鼠和人发现，感染性和自身免疫性肠道炎症都与肠道扩张有关， ILF和改变的Treg动力学。然而，没有数据表明这些变化如何影响定位， 维持炎症并从炎症中恢复。在我们的第二个目标中，我们将研究小鼠模型， 炎症和IBD患者的标本，以确定炎症如何改变ILF-Treg相互作用。 3.方法学：将具有改变的MHCII表达的小鼠与野生型小鼠进行比较。小肠 我们的数据表明胸腺T细胞优先定位于ILF，IBD患者也将 考察免疫系统将利用封闭抗体，抗生素，基因操作， 和感染方法将包括细胞群体的分子和细胞分析以及通过流动的反应。 流式细胞术、表达谱和成像技术。 4.结论：该提案未得到资助。 5.临床关系：炎症性肠病的患病率一直在增加， 老兵目前的研究是针对定义的途径，可以操纵治疗， 增加局部调节性T细胞的数量，以改善IBD结果。

1. Objective: Inflammatory bowel diseases (IBD), including Crohns Disease and Ulcerative Colitis, arise in genetically-susceptible hosts when intestinal epithelial defects and heightened responsiveness towards commensal organisms lead to excessive activation of CD4+ T cells and tissue damage. IBD is also associated with loss of regulatory pathways including defects in regulatory T cells (Tregs). Tregs, a subset of Foxp3- positive CD4+ T cells, are central to intestinal tolerance; they prevent the development of IBD disease and suppress inflammation during infection. In this application, we seek to understand the mechanisms that maintain intestinal Tregs during health and inflammation. Regulatory T cells include two developmentally distinct subsets: thymus-derived (tTreg or natural (nTreg) and peripherally-derived (pTreg) that differentiate from conventional naïve CD4+ T cells. Human and mouse intestine contain cells of both lineages and both are necessary to maintain tolerance. Foxp3-deficient IPEX patients, lacking natural Tregs, develop autoimmune enteritis as infants. Separately, loss of the genomic region that controls peripheral differentiation of pTregs also leads to intestinal inflammation. Thus, both murine and human studies demonstrate a requirement for both populations for the maintenance of intestinal tolerance. There are no data defining distinct mechanistic or anatomic requirements for the two populations. Treg localization and phenotypes were examined in mice lacking peripheral TCR-MHCII interactions and peripheral conversion of Tregs (pTregs). Thymically-generated nTregs entered the small intestine lamina propria (siLP) to fill the compartment in the absence of MHCII. Imaging of intact tissue shows that Tregs in the siLP have two distinct anatomic locations: individually localized within the siLP villus or clustered within organized structures resembling isolated lymphoid follicles (ILFs). Our data suggest that a subset of Tregs preferentially localize to ILFs; this association is altered during infection. Additionally, nTregs and pTregs occupy an overlapping niche despite having different requirements for costimulatory signals. Thus, we present the hypotheses that 1. thymic-derived and peripheral Tregs occupy distinct physiologic niches in the small intestine, and 2 ILFs provide a niche for Tregs that is malleable during inflammation. 2. Research Design: In our first Aim, we will utilize murine models and healthy human tissue to determine if ILFs are required for the maintenance of siLP Tregs, define the costimulatory signals present in the ILF, and then ask if the ILF specifically attracts and maintains thymic Tregs in contrast to pTregs. Multiple studies in mice and men find that both infectious and autoimmune intestinal inflammation is associated with expansion of ILFs and altered Treg dynamics. Yet, there are no data on how these changes affect the positioning and maintenance of Tregs and recovery from inflammation. In our second Aim, we will examine murine models of inflammation and specimens from IBD patients to define how inflammation alters ILF-Treg interactions. 3. Methodology: Mice with altered MHCII expression will be compared with wildtype mice. Small intestine from healthy Our data suggest thymic Tregs preferentially localize to ILFs.and IBD patients will also be examined. The immune system will be altered utilizing blocking antibodies, antibiotics, genetic manipulations, and infections. Methods will include molecular and cellular analyses of cell populations and responses by flow cytometry, expression profiling, and imaging techniques. 4. Findings: This proposal not been funded. 5. Clinical Relationships: The prevalence of inflammatory bowel disease has been increasing amongst veterans. The current study is directed towards defining pathways that can be manipulated therapeutically to increase the number of localized regulatory T cells to improve IBD outcomes.