Mechanisms of Salmonella-mediated disruption of colonization resistance in the inflamed gut

沙门氏菌介导的炎症肠道定植抵抗破坏机制

• 批准号: 10595200
• 负责人: Mariana Xavier Byndloss
• 金额: $ 47.34万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-19 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10595200
• 关键词: Affect; Amino Acids; Anaerobic Bacteria; Aspartate; Bacteria; Bacteroides; Bacteroides thetaiotaomicron; Catabolism; Citric Acid Cycle; Cytolysis; Data; Ecosystem; Enterobacteriaceae; Epithelial Cells; Escherichia coli; Fluorescence Microscopy; Fumarates; Gastroenteritis; Gastrointestinal tract structure; Genes; Genetic Transcription; Germ-Free; Growth; In Vitro; Infection; Inflammation; Intestines; Invaded; Measures; Mediating; Metabolic; Metabolism; Mus; Nitrates; Nutrient; Oxidants; Pathogenesis; Pathway interactions; Phase; Physiology; Play; Production; Propionates; Reactive Oxygen Species; Reporter; Research; Respiration; Role; Salmonella; Salmonella typhimurium; Source; Study models; Taxon; Testing; Type III Secretion System Pathway; United States; Virulence; Volatile Fatty Acids; Work; antimicrobial; colonization resistance; commensal bacteria; commensal microbes; diarrheal disease; enteric pathogen; essays; experimental study; gut inflammation; gut microbiota; host microbiota; in vivo; innovation; intestinal epithelium; microbial; microbiota; mouse model; mutant; non-typhoidal Salmonella; novel; pathogen; pathogenic bacteria; resident commensals; response

PROJECT SUMMARY Infection with non-typhoidal Salmonella is 1 of 4 most prevalent global causes of diarrheal disease. In the United States, Salmonella enterica serovar Typhimurium (S. Tm) infection results in 1.35 million illnesses annually. To infect the gastrointestinal tract, S. Tm contends with the resident commensal bacteria (gut microbiota). The gut microbiota benefits the host by limiting enteric pathogen expansion (colonization resistance), partially via the production of inhibitory metabolites such as short-chain fatty acids (SCFA) (e.g., propionate) and nutrient sequestration (e.g., amino acids). Thus, successful bacterial pathogens must possess mechanisms to survive in the competitive ecosystem of the gut. S. Tm uses a Type III secretion system (T3SS- I) to invade intestinal epithelial cells (EICs) and induce intestinal inflammation. As a result, S. Tm disrupts the host-microbiota ecosystem and overcomes microbiota-mediated colonization resistance by using inflammation- derived electron acceptors such as fumarate and nitrate for anaerobic respiration. However, the mechanisms that drive Salmonella-induced disruption of the microbial ecosystem in the gut and how this disruption affects host physiology and promotes pathogen expansion remain largely unknown. In this application, we will elucidate the mechanisms by which S. Tm-induced intestinal inflammation enables the pathogen to (i) overpower SCFA- mediated colonization resistance and (ii) gain access to microbiota-derived aspartate for anaerobic fumarate respiration. Our robust preliminary data obtained from in vitro studies and murine models demonstrate that the pathogen may use propionate metabolism to fine-tune virulence through modulation of T3SS-I expression. Our studies further reveal that S. Tm-induced inflammation causes an increase in Bacteroides-derived aspartate in the intestinal lumen and that aspartate conversion into fumarate fuels S. Tm fumarate respiration in vitro and in vivo. Our preliminary data support our central hypothesis that pathogen-induced intestinal inflammation allows S. Tm to overcome mechanisms of colonization resistance established by the microbiota by (i) downregulating invasion of EICs via catabolism of Bacteroides-derived propionate and (ii) promoting the release of aspartate by commensal Bacteroides, which S. Tm uses to outcompete commensal Enterobacteriaceae. To test this hypothesis, we will define the impact of propionate catabolism on S. Tm pathogenesis in the inflamed gut (Aim 1). Aim 2 will identify the mechanism by which intestinal inflammation promotes increased aspartate availability in the inflamed gut. In Aim 3, we will determine how aspartate enables S. Tm to overcome colonization resistance by Enterobacteriaceae, a bacterium taxon that plays a critical role in protecting the host against S. Tm infection. If successful, this research will establish critical conceptual advances in understanding how enteric pathogens exploit the gut microbiota for expansion during gastroenteritis. Expected findings will provide a deeper understanding of a novel mechanism used by this bacterial pathogen to evade the intestinal microbiota and establish infection.

项目摘要 非细类沙门氏菌的感染是4个最普遍的全球腹泻病因中的1个。在 美国，沙门氏菌肠孢子虫（S. TM）感染导致135万疾病 每年。为了感染胃肠道，S。TM与居民共生细菌抗衡（肠道 微生物群）。肠道菌群通过限制肠道病原体的扩张（定殖）使宿主受益 耐药性），部分通过产生抑制性代谢物，例如短链脂肪酸（SCFA）（例如， 丙酸）和养分隔离（例如氨基酸）。因此，成功的细菌病原体必须拥有 在肠道的竞争生态系统中生存的机制。 S. TM使用III型分泌系统（T3SS- i）入侵肠上皮细胞（EICS）并诱发肠道炎症。结果，S。TM破坏了 通过使用炎症 - 衍生的电子受体，例如富马酸盐和硝酸盐，用于厌氧呼吸。但是，机制 这推动沙门氏菌引起的肠道中微生物生态系统的破坏以及这种破坏如何影响 宿主生理学并促进病原体的扩张仍然很大未知。在此应用程序中，我们将阐明 S. tm诱导的肠炎的机制使病原体（i）压倒SCFA- 介导的定殖耐药性和（ii）获得厌氧富马酸盐的微生物衍生的天冬氨酸 呼吸。我们从体外研究获得的强大初步数据和鼠模型表明 病原体可以通过调节T3SS-I表达来使用丙酸代谢来微调毒力。我们的 研究进一步表明，链球菌诱导的炎症会导致细菌衍生的天冬氨酸的增加 肠腔和天冬氨酸转化为富马酸盐的燃料S. TM富马酸盐呼吸，体外和IN 体内。我们的初步数据支持了我们的中心假设，即病原体引起的肠炎允许 S. tm以克服微生物群建立的定植抗性机制，通过（i）下调 通过细菌衍生的丙酸酯的分解代谢和（ii）促进天冬氨酸释放的侵袭EICS S. tm使用的共生细菌型杀菌型。测试这个 假设，我们将定义丙酸分解代谢对发炎肠炎的TM发病机理的影响（AIM 1）。 AIM 2将确定肠道炎症促进天冬氨酸供应量增加的机制 在发炎的肠道中。在AIM 3中，我们将确定天冬氨酸如何使S. TM克服定殖抗性 由肠杆菌科，一种细菌分类群，在保护宿主免受S. tm感染中起着至关重要的作用。 如果成功，这项研究将在理解肠道病原体方面建立关键的概念进步 利用肠道菌群在胃炎期间扩张。预期的发现将提供更深的 了解这种细菌病原体使用的一种新机制，以逃避肠道菌群和 建立感染。