A. actinomycetemcomitans Cdt induces pro-inflammatory innate immune responses

A. actinomycetemcomitans Cdt 诱导促炎先天免疫反应

• 批准号: 9237252
• 负责人: BRUCE J SHENKER
• 金额: $ 40万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2019-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9237252
• 关键词: 1-Phosphatidylinositol 3-Kinase; AKT Signaling Pathway; Actinobacillus actinomycetemcomitans; Agonist; Antigens; Apoptosis; Apoptotic; Bacteria; Carrier Proteins; Cell Cycle Arrest; Cell Death; Cell Degranulation; Cell Line; Cell membrane; Cells; Dinoprostone; Disease; Exhibits; Future; GLUT4 gene; Generations; Glucose; Goals; Host Defense; Human; Immune response; Immune system; Immunosuppression; Immunosuppressive Agents; Immunotoxins; Impairment; Infection prevention; Inflammation Mediators; Inflammatory; Inflammatory Response; Inflammatory Response Pathway; Innate Immune Response; Innate Immune System; Interleukin-1 beta; Interleukin-13; Interleukin-6; Intracellular Membranes; Investigation; Leukotriene B4; Leukotrienes; Lipid Binding; Lipids; Lymphocyte; Mediating; Mediator of activation protein; Membrane Microdomains; Metabolic; Microbe; Natural Immunity; Operon; Organism; PTEN gene; Pathogenesis; Pathogenicity; Pathway interactions; Periodontal Diseases; Pharmacology; Phosphatidylinositols; Phosphoric Monoester Hydrolases; Play; Predisposition; Production; Proliferating; Prostaglandins; Proteins; Role; Signal Pathway; Signal Transduction; T-Lymphocyte; TLR2 gene; TNF gene; Testing; Toxic effect; Toxin; Tumor Suppressor Proteins; Vesicle; Virulence; adaptive immune response; adaptive immunity; cellugyrin; cytokine; cytolethal distending toxin; experimental study; glucose uptake; glycogen synthase kinase 3 beta; holotoxins; immunological intervention; immunoregulation; in vivo; macrophage; mast cell; microorganism; microvesicles; mutant; novel; oral pathogen; pathogen; protein transport; public health relevance; response; trafficking; tripolyphosphate

DESCRIPTION (provided by applicant): The immune system, by and large, plays a primary role to minimize and/or prevent infection, in general, and periodontal disease, in particular. We propose that perturbation of both innate and adaptive immune responses contribute to the pathogenesis of and susceptibility to periodontal disease. The fundamental hypothesis of our studies is that periodontal pathogens produce immunomodulatory proteins that alter either innate or adaptive immunity, thereby enhancing their own virulence and/or that of other opportunistic microorganisms. Our investigations have demonstrated that Aggregatibacter actinomycetemcomitans produces an immunotoxin, the cytolethal distending toxin (Cdt), that impairs human T-cells by inducing cell cycle arrest and apoptosis. In this proposal we focus on a novel, nonlethal, effect of Cdt on two critical cells that comprise the innate immune system. Specifically, we propose the Cdt induces a pro-inflammatory response by virtue of its ability to act as a PIP3 phosphatase, deplete cells of this critical signaling lipid and in turn block PI-3K signaling leading to decreased pAkt to activation of GSK3ß. Preliminary studies indicate that treatment of the human macrophage cell line, THP1, and human macrophages with Cdt results in the synthesis and release of pro-inflammatory cytokines (TNFα and IL-1ß) as well as enhancement of TLR agonist-induced cytokine release. Cdt also augments de novo synthesis of cytokines (IL-6 and IL-13) following mast cell activation. These effects on both macrophages and mast cells are consistent with PIP3 depletion, blockade of the PI-3K signaling pathway and the role of this pathway as a negative regulator of the pro-inflammatory response. We now plan to extend these preliminary studies to define the extent and mechanism by which Cdt alters the synthesis and release of inflammatory mediators by human macrophages and mast cells. The study is divided into three specific aims: (1) To define the pro-inflammatory effects of Cdt on the innate immune response of macrophages and mast cells; ( 2) To determine if the Cdt-mediated pro-inflammatory effects on the innate immune system ais dependent upon PIP3 phosphatase activity and altered PI-3K/PIP3/Akt signaling; and (3) To determine the role of cellugyrin and, possibly GSK3ß, in Cdt-mediated altered glucose uptake and utilization and its relationship to the pro-inflammatory response. It is anticipated that these studies will lead to a more detailed understanding of Cdt mode of action and contribute to a greater understanding of the pathogenesis of disease caused by Cdt-producing bacteria. In addition to advancing our understanding of Cdt mode of action, these studies will advance our understanding of the mechanism(s) by which the PI-3K signaling pathway regulates TLR-mediated cytokine production. Thus these studies will identify new targets for future in vivo studies involving pharmacologic and immunologic intervention in disease caused by bacteria that produce Cdt.

描述（由申请人提供）：免疫系统，总的来说，在减少和/或预防感染，特别是牙周病方面起主要作用。 我们认为先天性免疫和适应性免疫反应的紊乱与牙周病的发病机制和易感性有关。我们的研究的基本假设是，牙周病原体产生免疫调节蛋白，改变先天性或适应性免疫，从而提高自己的毒力和/或其他机会微生物。我们的研究表明，伴放线聚集杆菌产生的免疫毒素，细胞致死膨胀毒素（Cdt），损害人类T细胞诱导细胞周期阻滞和凋亡。在这项提案中，我们专注于一个新的，非致命的，Cdt对两个关键细胞，包括先天免疫系统的影响。具体而言，我们提出Cdt通过其充当PIP 3磷酸酶的能力诱导促炎反应，耗尽细胞中的这种关键信号脂质，进而阻断PI-3 K信号传导，导致pAkt降低以激活GSK 3 K。 初步研究表明，用Cdt处理人巨噬细胞系THP 1和人巨噬细胞导致促炎细胞因子（TNFα和IL-1 β）的合成和释放以及TLR激动剂诱导的细胞因子释放的增强。Cdt还增强肥大细胞活化后细胞因子（IL-6和IL-13）的从头合成。对巨噬细胞和肥大细胞的这些作用与PIP 3消耗、PI-3 K信号传导途径的阻断以及该途径作为促炎反应的负调节剂的作用一致。我们现在计划扩展这些初步研究，以确定Cdt改变人巨噬细胞和肥大细胞合成和释放炎症介质的程度和机制。本研究分为三个具体的目的：（1）确定Cdt的促炎作用， 巨噬细胞和肥大细胞的先天性免疫应答;（2）确定Cdt介导的对先天性免疫系统的促炎作用是否依赖于PIP 3磷酸酶活性和改变的PI-3 K/PIP 3/Akt信号传导;和（3）确定胞浆蛋白和可能的GSK 3 K在Cdt介导的改变的葡萄糖摄取和利用中的作用及其与促炎应答的关系。预计这些研究将导致更详细地了解Cdt的作用模式，并有助于更好地了解由Cdt产生细菌引起的疾病的发病机制。除了推进我们对Cdt作用模式的理解外，这些研究还将推进我们对PI-3 K信号通路调节TLR介导的细胞因子产生的机制的理解。因此，这些研究将确定新的目标，为未来的体内研究，涉及药物和免疫干预的疾病引起的细菌，产生Cdt。