The role of Mycobacterium marinum protein ESAT-6 in promoting granuloma formation

海分枝杆菌蛋白ESAT-6在促进肉芽肿形成中的作用

• 批准号: 8122119
• 负责人: Frances Chu
• 金额: $ 5.3万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8122119
• 关键词: 6-kDa early secretory antigenic target; Address; Amino Acid Substitution; Apoptosis; Binding; Biochemical Genetics; Cell Line; Cells; Coupled; Development; Disease; Drug Delivery Systems; Drug Resistant Tuberculosis; Embryo; Epithelial; Epithelial Cells; Epitopes; Extracellular Matrix; Family; Gelatinase B; Genus Mycobacterium; Granuloma; HIV; Human; Immune; Immune system; In Vitro; Infection; Inflammatory; Integration Host Factors; Laboratories; Larva; Lead; Light; Mediating; Membrane; Microscopic; Modeling; Multi-Drug Resistance; Mycobacterium Infections; Mycobacterium marinum; Mycobacterium tuberculosis; Optics; Pathogenesis; Pathology; Peptide Hydrolases; Play; Prevalence; Process; Proteins; Recruitment Activity; Regulation; Research; Role; Signal Transduction; Structure; System; Techniques; Time; Tuberculosis; Virulence; Zebrafish; cell motility; global health; insight; killings; macrophage; member; migration; mutant; mycobacterial; pandemic disease; pathogen; public health relevance; research study; resistant strain; unpublished works

DESCRIPTION (provided by applicant): Mycobacteria employ several mechanisms to exploit the host immune system for its own benefit. Rather than being killed by macrophages, specialized immune cells that normally engulf and eradicate pathogens, mycobacteria survive and persist by using macrophages as their host niche. The infected macrophages then recruit additional macrophages and other immune cells to the infection foci to form a granuloma, an organized aggregate of immune cells that is a hallmark of tuberculous infections. Although traditionally thought to be a host-protective structure, recent evidence from the Mycobacterium marinum- zebrafish model of infection has demonstrated that mycobacteria exploit the developing granuloma as a means to disseminate infection. It does so by secreting the bacterial factor ESAT-6 which induces the expression of host matrix metalloproteinase-9 (MMP9) from epithelial cells. MMP9 is a member of a larger family of proteases that modify the extracellular matrix, as well as cell migration and inflammatory molecules. During mycobacterial infections, MMP9 is required for the recruitment of macrophages to the developing granuloma. This proposal will investigate the mechanism by which ESAT-6 induces MMP9 secretion to promote granuloma development. I will begin by determining if ESAT-6 is necessary for the activation of mmp9 expression or if additional bacterial secreted factors play a role. I will take advantage of the optical transparency of zebrafish embryos to investigate if ESAT-6 is sufficient to induce macrophage recruitment, as infection may be required for granuloma formation. I hypothesize that ESAT-6 interacts directly with epithelial cells to induce mmp9 expression and will investigate this in vitro using human epithelial cell lines. I will identify the host determinant that binds to ESAT- 6 and transmits the granuloma-promoting signal. Lastly, I will employ mutational analysis to determine which regions of ESAT-6 are required for mmp9 expression. The experiments outlined in this proposal will shed light on the mechanisms employed by mycobacteria to exploit the host immune system and promote pathogenesis. PUBLIC HEALTH RELEVANCE: Due to the increasing prevalence of multi-drug resistant strains of Mycobacterium tuberculosis, coupled with the HIV pandemic, human tuberculosis disease remains a major global health problem. This proposal will investigate the interactions between host and pathogen factors during mycobacterial infections. These experiments may lead to the discovery and characterization of new host drug targets and reduce the time required to treat drug-resistant tuberculosis infections. )

描述（由申请方提供）：分枝杆菌利用几种机制利用宿主免疫系统为其自身利益服务。分枝杆菌不是被巨噬细胞杀死，而是通过使用巨噬细胞作为其宿主生态位而存活和持续存在。然后，受感染的巨噬细胞将额外的巨噬细胞和其他免疫细胞募集到感染灶以形成肉芽肿，这是结核感染的标志性免疫细胞的有组织聚集体。虽然传统上认为是宿主保护性结构，但最近来自海分枝杆菌-斑马鱼感染模型的证据表明，分枝杆菌利用发展中的肉芽肿作为传播感染的手段。其通过分泌细菌因子ESAT-6来实现，所述细菌因子ESAT-6诱导宿主基质金属蛋白酶-9（MMP 9）从上皮细胞的表达。MMP 9是一个较大的蛋白酶家族的成员，其修饰细胞外基质以及细胞迁移和炎症分子。在分枝杆菌感染期间，MMP 9是巨噬细胞向发展中的肉芽肿募集所必需的。 本提案将研究ESAT-6诱导MMP 9分泌以促进肉芽肿发展的机制。我将开始确定ESAT-6是否是激活mmp 9表达所必需的，或者是否有其他细菌分泌因子起作用。我将利用斑马鱼胚胎的光学透明度来研究ESAT-6是否足以诱导巨噬细胞募集，因为肉芽肿形成可能需要感染。 我假设ESAT-6直接与上皮细胞相互作用，诱导mmp 9表达，并将在体外使用人类上皮细胞系研究这一点。我会找出与ESAT- 6结合并传递肉芽肿促进信号的宿主决定簇。最后，我将采用突变分析来确定mmp 9表达所需的ESAT-6区域。本提案中概述的实验将阐明分枝杆菌利用宿主免疫系统和促进发病机制的机制。 公共卫生关系：由于结核分枝杆菌的多药耐药菌株的日益流行，加上HIV大流行，人类结核病仍然是一个主要的全球健康问题。本研究旨在探讨分枝杆菌感染过程中宿主与病原体之间的相互作用。这些实验可能导致发现和表征新的宿主药物靶点，并减少治疗耐药结核病感染所需的时间。)