Inflammatory cascades disrupt Treg function through epigenetic mechanisms

项目摘要/摘要 CD4+FOXP3+淋巴细胞在克罗恩病(CD)的肠炎性病变内扩张； 然而，持续的炎症掩盖了假定的该细胞的抗炎功能。Foxp3是必需的 T调节(Treg)细胞的分化和功能。Foxp3介导的基因抑制在肠道中丢失 CD患者的T细胞。事实上，“FOXP3+克罗恩细胞(FOXP3+CD)”承载着更多的转录信号 与促炎细胞TH17密切相关。血管内皮生长因子的来源、功能和治疗意义 Foxp3+CD细胞目前仍知之甚少。我们的长期目标是剖析表观遗传调控机制 Treg细胞在胃肠道炎症中的分化和功能。因此，目标是 确定肠道内TH17表型转录网络激活的机制 Foxp3+CD细胞，并测试治疗机会，以恢复其体内的调节功能。我们的中央 假设Treg和TH17细胞之间的共同染色质配置允许快速激活 在肠道FOXP3+Treg细胞中发现类似TH17的致炎基因程序。一组与TH17相关的基因 在人类Treg细胞中是可访问的，但不活跃。TH17计划的一个重要特征是 CCCTC结合因子(CTCF)基序的丰富。CTCF，一种广为人知的拓扑关联域 (TAD)绝缘体蛋白，也介导TAD染色体内的环和增强子-启动子相互作用 调节基因转录。对TH17程序的生物信息学分析表明，该程序具有抑制作用 多梳抑制物复合体1(Prc1)。小鼠FOXP3+细胞中Prc1基因缺失导致分泌 FOXP3+细胞中典型的TH17样细胞因子和自发性结肠炎。其基本原理是机械论 深入了解肠道炎症中Treg细胞的生物学，可以应用靶向FOXP3+CD细胞 治疗包括用于过继细胞治疗试验的人类Treg细胞的工程。为了测试中央 假设和获得总体目标我们将解决以下三个问题：Aim1：为什么CTCF 与TH17计划有关的主题？AIM2：为什么TH17相关基因可获得，但在 特雷格细胞？Aim3：为什么FOXP3+CD细胞表达原型TH17细胞因子？在结束时，我们将 了解产生FOXP3+CD细胞的表观遗传途径和3D染色质结构 塑造其发展和功能的机制。这一贡献意义重大，因为FOXP3+CD细胞 在克罗恩病变中扩增的表型为TH17细胞，与克罗恩病(和其他疾病)有关 炎症性疾病)，并代表了系统性或再工程的重要表观遗传药物靶点 细胞疗法。FOXP3+Treg细胞转化为致病细胞的风险是公认的 克罗恩试验中Foxp3+TH17样细胞的收养转移；然而，这个项目是第一个将两者结合在一起的项目 调节Treg细胞中TH17程序激活的签名和精确的表观遗传事件。

PROJECT SUMMARY/ABSTRACT CD4+FOXP3+lymphocytes are expanded within the intestinal inflammatory lesion of Crohn’s disease (CD); however, ongoing inflammation belies presumed anti-inflammatory function of this cell. FOXP3 is required for differentiation and function of T regulatory (TREG) cells. FOXP3-mediated gene repression is lost in intestinal T cells of CD patients. Indeed, “FOXP3+ Crohn’s cell (FOXP3+CD)” bears a transcriptional signal more closely related to the pro-inflammatory TH17 cell. Derivation, function, and therapeutic implications of the FOXP3+CD cell remain poorly understood. Our long-term goal is to dissect epigenetic mechanisms regulating TREG cellular differentiation and function in the setting of GI inflammation. Consequently, the objective is to identify mechanisms responsible for activation of the TH17 phenotypic transcriptional network within intestinal FOXP3+CD cells and test therapeutic opportunities to restore their regulatory function in vivo. Our central hypothesis is that a shared chromatin configuration between TREG and TH17 cells allows for rapid activation of a TH17-like pro-inflammatory gene program in intestinal FOXP3+TREG cells. A set of TH17-relevant genes are accessible, yet not active in human TREG cells. A defining feature of the TH17 program was significant enrichment of CCCTC binding factor (CTCF) motifs. CTCF, a well-known topologically-associated domain (TAD) insulator protein, also mediates intra-TAD chromosomal looping and enhancer-promoter interaction regulating gene transcription. Bioinformatic analysis of this TH17 program indicates an inhibitory role for Polycomb Repressor Complex 1 (PRC1). Deletion of PRC1 in murine FOXP3+ cells led to secretion of prototypic TH17-like cytokines in FOXP3+ cells, and spontaneous colitis. The rationale is that with mechanistic insight into the biology of intestinal TREG cell in inflammation, one can apply targeted FOXP3+ CD cell-directed therapy including engineering of human TREG cells for adoptive cell therapy trials. To test the central hypothesis and obtain the overall objective we will address the following three questions: Aim1: Why are CTCF motifs associated with the TH17 program? Aim2: Why are TH17-associated genes accessible yet not active in TREG cells? Aim3: Why do FOXP3+CD cells express prototypic TH17 cytokines? Upon conclusion, we will understand the epigenetic pathways and 3D chromatin architecture spawning the FOXP3+CD cell and mechanisms shaping their development and function. This contribution is significant as the FOXP3+CD cell is expanded in the Crohn’s lesion, phenocopies TH17 cell which is implicated in Crohn’s disease (and other inflammatory diseases), and represents an important epigenetic drug target for systemic or re-engineered cellular therapy. There is general acknowledgement of risk of FOXP3+ TREG cells converting to pathogenic FOXP3+TH17-like cells upon adoptive transfer in Crohn’s trials; yet, this project is the first to articulate both signature and precise epigenetic events that regulate activation of the TH17 program in TREG cells.