Role of the environmental sensor, AhR on colitis

环境传感器，芳香烃受体(AhR)是污染物的配体，也是 用于植物、微生物和内源化合物。AhR连接后，激活的AhR调节基因 通过AhR/Arnt复合体与称为二恶英反应的特定DNA基序结合来表达 元素(DRE)。来自我们实验室和其他地方的研究表明，一些AhR配体具有 免疫抑制特性。炎症性肠病(IBD)是由慢性炎症引起的。 影响美国150万人的胃肠道疾病。IBD发病机制复杂 肠道微生物区系、免疫反应、环境和饮食因素之间的相互作用 遗传/表观遗传调控。最近，我们做了一个令人兴奋的观察，AhR配体和植物产物， I3C可改善小鼠结肠炎，其机制与抗炎、调节肠道菌群失调、 促进结肠上皮细胞表达β防御素(mBD1，2，3)。β-防御素组成 抗菌肽(AMPs)，可抵抗结肠组织中上皮表面的微生物定植。β- 防御素也可能起到抗炎作用。事实上，研究表明，表达有缺陷的 肠道AMP，尤其是IBD患者的防御素。我们很兴奋地在发起人中发现了DRE 小鼠β-防御素(mBd1、2和3)。在目前的研究中，我们将检验饮食中吲哚的中心假设 (I3C)通过激活AhR通过途径增加CECs Mbds的表达来减轻结肠炎 涉及DRE和/或表观遗传调控导致微生物区系的调节和预防上皮细胞 障碍物损坏。此外，我们认为，I3C诱导的MBDS在恢复健康肠道中起着关键作用 微生物区系，通过诱导肠道屏障损伤和抑制结肠炎 特雷格斯。目的1测试饮食吲哚诱导多器官功能减退的机制。我们将使用报告分析，发起人 敲击和电泳迁移率改变分析以确定I3C激活的AhR是否直接与 DRES诱导MBDS。我们还将通过AhR CKO小鼠来确定I3C对Mbd表达的影响 IEC、ILC3和Tregs中AhR缺失。在目标2中，我们将研究饮食对β-防御素的表观遗传调节。 吲哚。为此，我们将测试I3C是否通过改变组蛋白修饰和 减少DNA甲基化。我们将具体确定I3C是否调节SATB1介导组蛋白 去乙酰化和染色质重塑。在目标3中，我们将测试MBDS的管理是否提供保护 通过调节肠道代谢、预防CEC屏障损伤、增强Treg亚群和降低 Th17亚群，以减轻结肠炎。最后，我们将使用MBD KO小鼠来测试MBDS 是I3C介导的结肠炎保护所必需的。拟议的研究具有重要意义，因为它们 将确定饮食吲哚通过改变微生物区系抑制结肠炎的新机制，通过 AhR的激活导致宿主来源的AMP，特别是β-防御素的表达增加。

The environmental sensor, aryl hydrocarbon receptor (AhR) serves as a ligand for pollutants as well as for plant, microbial and endogenous compounds. Following AhR ligation, the activated AhR regulates gene expression through the binding of AhR/ARNT complex to specific DNA motifs known as Dioxin Response Elements (DREs). Studies from our lab and elsewhere have shown that some AhR ligands have potent immunosuppressive properties. Inflammatory bowel disease (IBD) results from chronic inflammation in the gastrointestinal tract that affects 1.5 million people in the US. The pathogenesis of IBD involves complex interactions between gut microbiota, immune response, environmental and dietary factors, and genetic/epigenetic regulation. Recently, we made an exciting observation that the AhR ligand and plant product, I3C ameliorates colitis in mice, which was associated with anti-inflammatory effects, regulation of gut dysbiosis, and enhanced expression of β-defensins (mBD1,2,3) by Colonic Epithelial Cells (CEC). β-defensins constitute antimicrobial peptides (AMPs) that resist microbial colonization of epithelial surfaces in the colonic tissue. β- defensins may also mediate anti-inflammatory effects. In fact, studies have shown defective expression of intestinal AMPs particularly defensins in IBD patients. We were excited to uncover DREs in the promoters of mouse β-defensins (mBD1, 2, and 3). In the current study, we will test the central hypothesis that dietary indoles (I3C) attenuate colitis through AhR activation leading to increased expression of mBDs by CECs via pathways involving DREs, and/or epigenetic regulation resulting in modulation of microbiota and prevention of epithelial barrier damage. Furthermore, we propose that mBDs induced by I3C play a critical role in restoring healthy gut microbiota, preventing intestinal barrier damage and suppressing colonic inflammation through induction of Tregs. Aim 1 will test the mechanisms of mBD induction by dietary indoles. We will use reporter assay, promoter bashing and electrophoretic mobility shift assay to determine whether I3C activated AhR directly binds to the DREs to induce mBDs. We will also determine the effect of I3C on the mBD expression by using AhR cKO mice with AhR deletion in IEC, ILC3 and Tregs. In Aim 2, we will study epigenetic regulation of β-defensins by dietary indoles. To that end, we will test whether I3C regulates mBD expression by altering histone modification and decreasing DNA methylation. We will specifically determine if I3C regulates the SATB1-mediated histone deacetylation and chromatin remodeling. In Aim 3, we will test whether administration of mBDs offers protection from colitis by regulating gut dysbiosis, preventing CEC barrier damage, enhancing Treg subsets and decreasing Th17 subpopulations to attenuate colonic inflammation. Finally, we will use mBD KO mice to test whether mBDs are required for I3C-mediated protection from colitis. The proposed studies are highly significant because they will identify novel mechanisms through which dietary indoles suppress colitis by altering the microbiota, through activation of AhR leading to increased expression of host-derived AMPs, specifically β-defensins.