The impact of Aryl hydrocarbon receptor signaling on Toll like receptor-mediated inflammation

项目摘要/摘要 芳香烃受体(AhR)在调节免疫反应和暴露于 激活AHR的化合物，包括环境毒物，如二恶英，可能有助于 细胞因子的失调和免疫系统紊乱的发展。配体依赖的激活 AhR可促进炎性T辅助细胞Th17细胞分化或导致严重的免疫抑制 以及调节性T细胞的增加。在我们对AhR如何规范 树突状细胞(DC)和其他免疫细胞之间的细胞间和细胞内通讯过程 分子水平，这对理解生理和病理生理免疫都是至关重要的 通过AhR介导的反应。这项提案的总体目标是确定人力资源和人力资源管理局的职能作用 其特异性抑制物(AHRR)与Toll样受体(TLR)和NFkB信号相互作用的调控功能 分化为DC和T细胞活化。已报道AhR对TLR和NFkB信号的异常调节 配体可能是触发免疫系统紊乱的关键步骤。AhR的转录抑制因子，即 AHRR是在AhR途径中实现的，尽管在TLR和TLR水平上仍有许多需要阐明。 NFkB信令。在过度表达AHRR的转基因小鼠中，我们发现AHRR关键参与了 二恶英诱导的炎症基因表达及内毒素介导的炎症反应的调控 和内毒素休克。因此，AHRR TG小鼠使我们有机会认识AHRR是如何参与 调节TLR介导的反应和免疫系统的其他部分。骨髓来源的DC 遗传小鼠模型以及人类DC，将被用来研究DC是如何通过配体- 通过TLR/NFkB诱导AhR和炎症信号的激活。AhR/Rel的全基因组鉴定 将进行与结合位点相关的基因表达分析。结合位点的突变体将是 生成以验证是否确实需要特定的绑定事件来调节目标的表达 基因。蛋白质-蛋白质相互作用研究将确定AhR和Rel蛋白的特定相互作用区域 并深入了解这些相互作用如何影响每种蛋白质的功能活性以及 AHR/NFkB串扰。一种通过正电子发射无创监测体内免疫反应的新方法 断层扫描(免疫-PET)成像将最终显示AhR配体如何修饰TLR介导的 树突状细胞、中性粒细胞、B细胞和T细胞在体内的募集和聚集。这项研究可以提供一个明确的 暴露于AhR激活物与炎症发生的联系及机制 慢性病。研究结果将允许更清楚地定义终点来评估AhR的效果和毒性 激活包括环境污染物在内的配体。本研究也将为今后的研究提供新的思路 AhR和AHRR作为分子靶点的创新用途，用于治疗炎症、感染、 和慢性病。

Project Summary/Abstract The aryl hydrocarbon receptor (AhR) plays an important role in regulating immune responses and exposure to AhR-activating compounds, including environmental toxicants such as dioxins may contribute to the dysregulation of cytokines and the development of immune system disorders. The ligand-dependent activation of AhR can promote differentiation of inflammatory T helper Th17 cells or lead to profound immunosuppression and an increase of regulatory T cells. Significant gaps exist in our understanding of how the AhR regulates the inter- and intracellular communication processes between dendritic cells (DC) and other immune cells on the molecular level, which is of central importance to understanding both physiologic and pathophysiologic immune reactions mediated through AhR. The overall goal of this proposal is to identify the functional role of the AhR and its specific repressor (AhRR) interacting with Toll-like receptor (TLR) and NFkB signaling in controlling function and differentiation of DC and T-cell activation. The reported dysregulation of TLR and NFkB signaling by AhR ligands may be key steps in triggering immune system disorders. The transcriptional repressor of the AhR, the AhRR is implemented in the AhR pathway, although much remains to be elucidated at the level of TLR and NFkB signaling. In transgenic mice overexpressing AhRR we discovered that AhRR is critically involved in regulation of dioxin-induced inflammatory gene expression as well as LPS-mediated inflammatory responses and LPS shock. Thus, the AhRR Tg mice give us the opportunity to recognize how AhRR is involved in the regulation of TLR-mediated responses and other parts of the immune system. Bone-marrow derived DC from genetic mouse models as well as human DC, will be used to investigate how DC are regulated through ligand- induced activation of the AhR and inflammatory signals via TLR/NFkB. A genome-wide identification of AhR/Rel binding sites will be conducted and related to gene expression analysis. Mutants of binding sites will be generated to validate whether a particular binding event is actually required to regulate the expression of target genes. Protein-protein interaction studies will identify the specific interacting domains of AhR and Rel proteins and provide insight into how these interactions impact the functional activity of each protein and the outcome of AhR/NFkB crosstalk. A novel in vivo method to monitor immune responses noninvasively via Positron Emission Tomography (immuno-PET) imaging will be used to ultimately show how AhR ligands modify TLR-mediated recruitment and accumulation of DC, neutrophils, B cells, and T cells in vivo. This study can provide a definite link and mechanism between the exposure to AhR activating compounds and the development of inflammatory chronic diseases. Findings will allow for more clearly defined endpoints to assess the effects and toxicity of AhR activating ligands including environmental pollutants. This study will also provide new concepts for future innovative uses of AhR and AhRR as molecular targets for therapeutic applications in inflammation, infection, and chronic diseases.