Role of the environmental sensor, AhR on colitis

环境传感器，芳烃受体（AhR）作为污染物的配体以及 用于植物、微生物和内源性化合物。AhR连接后，激活的AhR调节基因 通过AhR/ARNT复合物与特定DNA基序的结合进行表达，称为二恶英反应 要素（DRE）。我们实验室和其他地方的研究表明，一些AhR配体具有有效的 免疫抑制特性。炎症性肠病（IBD）是由肠道中的慢性炎症引起的。 胃肠道疾病，影响美国150万人。IBD的发病机制涉及复杂的 肠道微生物群、免疫反应、环境和饮食因素之间的相互作用， 遗传/表观遗传调节。最近，我们做了一个令人兴奋的观察，AhR配体和植物产物， I3 C改善小鼠结肠炎，这与抗炎作用、调节肠道生态失调、 增强结肠上皮细胞（CEC）β-防御素（mBD 1、2、3）的表达。β-防御素构成 抗微生物肽（AMP），其抵抗结肠组织中上皮表面的微生物定殖。β-的 防御素也可介导抗炎作用。事实上，研究表明， 肠AMP特别是防御素。我们很高兴地发现， 小鼠β-防御素（mBD 1、2和3）。在目前的研究中，我们将测试中心假设，饮食吲哚 (I3C)通过AhR激活减轻结肠炎，导致CEC通过途径增加mBD表达 涉及DRE和/或表观遗传调节，导致微生物群的调节和上皮细胞的预防。 屏障损坏。此外，我们认为I3 C诱导的mBDs在恢复健康肠道中起着关键作用 微生物群，防止肠道屏障损伤和抑制结肠炎症，通过诱导 你好目的1：探讨吲哚类药物诱导mBD的机制。我们将使用报告基因分析，启动子 碰撞和电泳迁移率变动分析，以确定I3 C激活的AhR是否直接结合到 DRE诱导mBD。我们还将通过使用AhR cKO小鼠来确定I3 C对mBD表达的影响 在IEC、ILC 3和THEB中存在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控， 吲哚。为此，我们将测试I3 C是否通过改变组蛋白修饰来调节mBD表达， 降低DNA甲基化。我们将专门确定I3 C是否调节SATB 1介导的组蛋白 去乙酰化和染色质重塑。在目标3中，我们将测试给予mBD是否提供保护 通过调节肠道生态失调，防止CEC屏障损伤，增强Treg亚群和减少 Th 17亚群以减弱结肠炎症。最后，我们将使用mBD KO小鼠来测试mBD是否 是I3 C介导的结肠炎保护所必需的。这些研究非常重要，因为它们 将确定饮食吲哚通过改变微生物群来抑制结肠炎的新机制， 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.