The role of the human gut microbiota in modulating virulence of Enterohemorrhagic E. coli

人类肠道微生物群在调节肠出血性大肠杆菌毒力中的作用

• 批准号: 9378054
• 负责人: Elizabeth A Cameron
• 金额: $ 5.71万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9378054
• 关键词: Affect; Area; Bacteria; Bacteroides; Bacteroides thetaiotaomicron; Cessation of life; Cleaved cell; Colon; Communities; Complex; Consumption; Cues; Data; Disease; Disease Progression; Enteral; Enterocytes; Escherichia coli; Escherichia coli EHEC; Escherichia coli Infections; Gastrointestinal tract structure; Gene Expression; Gene Expression Regulation; Genetic Transcription; Glycosides; Goals; Health; Hemolytic-Uremic Syndrome; Hemorrhagic colitis; Home environment; Human; Immune system; Infection; Intestines; Laboratories; Lead; Mentors; Mucous body substance; Nutrient; Organism; Pathogenesis; Pathogenicity; Pathogenicity Island; Peptide Hydrolases; Physiology; Play; Polysaccharides; Process; Production; Proteins; Regulation; Research; Research Personnel; Role; Severities; Severity of illness; Shiga Toxin; Site; Succinates; Symbiosis; System; Testing; United States; Virulence; Virulence Factors; Work; commensal microbes; design; effective therapy; enteric pathogen; foodborne; foodborne pathogen; gut microbiota; member; metabolomics; microbial; microbial community; microbiota; mouse model; mucinase; novel; pathogen; prevent; research study

The human gastrointestinal tract is home to trillions of microbial organisms, collectively known as the gut microbiota, that play a critical function in maintaining human health by providing the host with nutrients, promoting maturation of the immune system and preventing colonization by pathogenic organisms. However, more recently it has been appreciated that certain members of the microbiota can actually exacerbate disease associated with enteric pathogens. Therefore, there is a critical need to investigate the effect of commensal species on the virulence of intestinal pathogens. Enterohemmorhagic E. coli (EHEC) is an important human food borne pathogen that causes 265,000 cases of bloody diarrhea year in the United States, which in severe cases can progress to hemolytic uremic syndrome or even death. EHEC encodes two principal virulence factors that contribute to disease: a type three secretion system (T3SS) encoded on a pathogenicity island known as the locus of enterocyte effacement (LEE), and Shiga Toxin. Previous studies have demonstrated that microbiota-derived products can modulate expression of these important virulence factors and affect the severity of disease. The objective of this proposal is to determine the effect of human gut commensals on EHEC associated disease. Our hypothesis is that members of the microbiota affect EHEC disease by modulating expression and activity of, and directly processing virulence factors. We have previously demonstrated that Bacteroides- produced succinate enhances LEE expression, leading to more severe EHEC disease. We will investigate the effect of other common gut commensals on EHEC disease and use metabolomics to identify the metabolites that may be eliciting these effects. We have also previously demonstrated that the presence of a common gut commensal, Bacteroides thetaiotaomicron (B. theta) leads to enhanced destruction of the host mucus layer during a mouse model of EHEC infection. We will investigate the mechanism of this enhanced mucus degradation and define the role of commensal mucosal glycan degradation in this process. Finally, we have demonstrated that B. theta-produced proteases are capable of cleaving EspB, a critical component of the EHEC T3SS, into two smaller products. We will identify the B. theta proteases responsible for this cleavage and functionally characterize the resulting cleavage products. Successful completion of the proposed work will reveal novel mechanisms of EHEC virulence modulation by the human gut microbiota. Understanding more about the factors that affect disease progression will allow us to design more effective therapies for this important human pathogen.

人类胃肠道是数万亿微生物的家园，统称为肠道微生物群，其通过为宿主提供营养、促进免疫系统成熟和防止病原生物定殖而在维持人类健康方面发挥关键作用。然而，最近已经认识到，微生物群的某些成员实际上可以加剧与肠道病原体相关的疾病。因此，有一个关键的需要，以调查的影响，肠道病原体的毒力的寄生虫物种。肠出血性大肠杆菌大肠杆菌（EHEC）是一种重要的人类食源性病原体，在美国每年导致265，000例出血性腹泻，严重者可发展为溶血性尿毒症综合征甚至死亡。肠出血性大肠杆菌编码两种主要的致病因子：一种是在称为肠上皮细胞消失位点（LEE）的致病岛上编码的第三型分泌系统（T3 SS），另一种是滋贺毒素。先前的研究表明，微生物源性产物可以调节这些重要毒力因子的表达，并影响疾病的严重程度。本提案的目的是确定人类肠道菌群对EHEC相关疾病的影响。我们的假设是，微生物群成员通过调节毒力因子的表达和活性以及直接加工毒力因子来影响EHEC疾病。我们先前已经证明类杆菌产生的琥珀酸盐增强LEE表达，导致更严重的EHEC疾病。我们将研究其他常见的肠道寄生虫对EHEC疾病的影响，并使用代谢组学来识别可能引起这些影响的代谢物。我们以前也证明了一种常见的肠道寄生菌，多形拟杆菌（B.θ）导致在EHEC感染的小鼠模型期间宿主粘液层的破坏增强。我们将研究这种增强的粘液降解的机制，并确定在此过程中的作用，胃粘膜聚糖降解。最后，我们证明了B.β-产生的蛋白酶能够将EHEC T3 SS的关键组分EspB切割成两种较小的产物。我们会找到B的。负责这种切割的θ蛋白酶，并在功能上表征所得的切割产物。这项工作的成功完成将揭示人类肠道微生物群调节EHEC毒力的新机制。更多地了解影响疾病进展的因素将使我们能够为这种重要的人类病原体设计更有效的疗法。