Role of the environmental sensor, AhR on colitis

环境传感器 AhR 对结肠炎的作用

基本信息

批准号：
10494130
负责人：
Mitzi Nagarkatti
金额：
$ 49.72万
依托单位：
UNIVERSITY OF SOUTH CAROLINA AT COLUMBIA
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-09-27 至 2026-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10494130
关键词：
3-Dimensional ARNT gene ATAC-seq Affect Anti-Inflammatory Agents Antiinflammatory Effect Aryl Hydrocarbon Receptor Attenuated Binding Biological Assay Broccoli - dietary CD4 Positive T Lymphocytes Cabbage - dietary Cauliflower Cells Chromatin Chronic Clinical Colitis Colon Colonic inflammation Complex Crohn&apos s disease DNA DNA Methylation Data Defensins Dietary Factors Dietary Indole Dietary Phytochemical Dioxins Disease model Electrophoretic Mobility Shift Assay Elements Environmental Pollutants Environmental Risk Factor Epigenetic Process Epithelial Epithelial Cells FOXP3 gene Gastrointestinal tract structure Gene Expression Genes Genetic Histone Acetylation Histone Deacetylase Histone Deacetylase Inhibitor Histone Deacetylation Human Immune response Immune system Immunomodulators Immunosuppression Indole-3-Carbinol Inflammation Inflammatory Bowel Diseases Interleukin-17 Intestines Knockout Mice Ligands Ligation Mediating MicroRNAs Modeling Mus Pathogenesis Pathway interactions Patients Peptides Persons Plants Play Prevention Property Protein Family Quantitative Reverse Transcriptase PCR Receptor Activation Regulation Regulatory T-Lymphocyte Reporter Resistance Response Elements Role Surface T cell differentiation T-Lymphocyte Testing Tissues Ulcerative Colitis antagonist antimicrobial peptide aryl hydrocarbon receptor ligand base beta-Defensins chromatin remodeling dextran sulfate sodium induced colitis epigenetic regulation gut dysbiosis gut microbiota histone modification intestinal barrier intestinal epithelium microbial microbial colonization microbial host microbiota murine colitis novel pollutant prevent promoter sensor transcription factor villin

项目摘要

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.

环境传感器芳烃受体 (AhR) 充当污染物的配体以及对于植物、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 复合物与特定 DNA 基序结合（称为二恶英反应）进行表达我们实验室和其他地方的研究表明，一些 AhR 配体具有有效的作用。免疫抑制特性。炎症性肠病（IBD）是由肠道慢性炎症引起的。影响美国 150 万人的胃肠道 IBD 综合征的发病机制涉及。肠道微生物群、免疫反应、环境和饮食因素之间的相互作用，以及最近，我们做了一个令人兴奋的观察，即 AhR 配体和植物产物， I3C 可改善小鼠结肠炎，这与抗炎作用、调节肠道菌群失调、结肠上皮细胞 (CEC) 的 β-防御素 (mBD1,2,3) 表达增强。抗菌肽（AMP）可抵抗结肠组织上皮表面的微生物定植。防御素也可能介导抗炎作用。事实上，研究表明防御素的表达存在缺陷。我们很高兴在 IBD 患者的启动子中发现 DRE。小鼠 β-防御素（mBD1、2 和 3）在本研究中，我们将检验饮食吲哚这一中心假设。 (I3C) 通过 AhR 激活减轻结肠炎，导致 CEC 通过途径增加 mBD 表达 DRE 和/或表观遗传调控可调节微生物群并预防涉及上皮细胞此外，我们认为 I3C 诱导的 mBD 在恢复健康肠道方面发挥着关键作用。微生物群，通过诱导肠道屏障损伤并抑制结肠炎症 Tregs 目标 1 将测试膳食吲哚诱导 mBD 的机制，我们将使用报告基因测定、启动子。敲击和电泳迁移率转向测定以确定 I3C 激活的 AhR 是否直接结合我们还将使用 AhR cKO 小鼠确定 I3C 对 mBD 表达的影响。 IEC、ILC3 和 Tregs 中的 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。为此，我们将测试 I3C 是否通过改变组蛋白修饰来调节 mBD 表达。我们将具体确定 I3C 是否调节 SATB1 介导的组蛋白。在目标 3 中，我们将测试 mBD 的施用是否能提供保护。通过调节肠道菌群失调、预防 CEC 屏障损伤、增强 Treg 亚群并减少结肠炎 Th17 亚群减轻结肠炎症最后，我们将使用 mBD KO 小鼠来测试 mBD 是否具有作用。 I3C 介导的结肠炎保护是必需的，因此拟议的研究非常重要，因为它们将确定膳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 表达增加，特别是 β-防御素。