Mechanism of Salmonella-dependent disruption of propionate-mediated colonization resistance

沙门氏菌依赖性破坏丙酸盐介导的定植抗性的机制

• 批准号: 10729845
• 负责人: CATHERINE SHELTON
• 金额: $ 3.29万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10729845
• 关键词: Ablation; Bacteroides; Bacteroides thetaiotaomicron; Carbon; Catabolism; Cessation of life; Colon; Complex; Data; Epithelial Cells; Exposure to; Fermentation; Fluorescence Microscopy; Gastroenteritis; Gastrointestinal tract structure; Genes; Germ-Free; Growth; In Vitro; Infection; Inflammation; Inflammatory Response; Intestines; Invaded; Literature; Measures; Mediating; Metabolism; Modeling; Mus; Nitrates; Nutrient; Operon; Oxidants; Oxygen; Pilot Projects; Production; Propionates; Pyruvate; Research; Respiration; Role; Salmonella; Salmonella enterica; Salmonella typhimurium; Series; Signal Transduction; Source; Testing; Toxic effect; Training; Volatile Fatty Acids; Work; bacterial community; colonization resistance; commensal bacteria; diarrheal disease; enteric pathogen; experimental study; gut colonization; gut inflammation; gut microbiota; in vivo; innovation; insight; member; microbiota; mouse model; mutant; non-typhoidal Salmonella; novel; pathogen; pathogenic bacteria; resident commensals; usability

PROJECT SUMMARY Infection with non-typhoidal Salmonella is a significant cause of diarrheal disease worldwide, causing approximately 150 million illnesses and 60,000 deaths each year. In the gastrointestinal tract, S. Tm encounters the resident commensal bacteria (gut microbiota). The gut microbiota protects the host against invading pathogens (colonization resistance) and limits pathogen expansion. Propionate, a short-chain fatty acid produced by members of the gut microbiota, is predicted to mediate colonization resistance against S. Tm by down-regulating invasion and inhibiting growth. As a successful pathogen, S. Tm may possess mechanisms to mitigate the toxic effects of propionate. Discovery of the prpBCDE operon, which enables S. Tm to metabolize propionate into pyruvate, provided initial insight into the ability of S. Tm to overcome propionate inhibition. However, it remains unknown under what conditions S. Tm uses the prpBCDE operon to eliminate intracellular propionate. During infection, the host's inflammatory response provides electron acceptors that allow S. Tm to metabolize diverse nutrients into carbon sources to support pathogen growth. My data suggests that propionate serves as a carbon source for S. Tm, specifically during anaerobic respiration when inflammation-derived electron acceptors are present. In preliminary experiments, I determined that inflammation-derived electron acceptors also alter propionate-dependent changes in expression of S. Tm invasion machinery. Thus, inflammation-derived electron acceptors may provide S. Tm with the opportunity to eliminate the inhibitory effects of propionate and fuel growth during infection. Indeed, my pilot studies demonstrate that propionate metabolism benefits S. Tm in vivo as a wildtype strain of S. Tm had a growth advantage over a prpC mutant strain in mouse models of S. Tm gastroenteritis. Therefore, the central hypothesis of this proposal is that S. Tm metabolizes propionate in the inflamed gut to regulate its invasion and support its luminal growth, ultimately allowing this pathogen to overcome propionate-dependent colonization resistance. To test this hypothesis, I will use an innovative combination of commensal members of the gut microbiota and S. Tm mutant strains along with germ- free and conventional mouse models to explore how S. Tm contends with propionate during infection. Experiments proposed in Aim 1 will determine if propionate serves as a carbon source to fuel S. Tm growth in vitro and in vivo. In Aim 2, I will identify if gut inflammation and anaerobic respiration are required for propionate metabolism to be beneficial to S. Tm during infection. Aim 3 will investigate if propionate metabolism not only fuels growth by providing a carbon source during respiration but by signaling to S. Tm to decrease invasion. If successful, this research will challenge the dogma that short-chain fatty acids inhibit Salmonella growth in the gut. This project will describe how S. Tm mitigates the detrimental effects of propionate by metabolizing this metabolite into a usable carbon source to fuel growth. 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 非伤寒沙门氏菌感染是世界范围内腹泻病的重要原因， 每年约有1.5亿人患病，6万人死亡。在胃肠道，S. TM遭遇 肠道微生物（gut microbiota）肠道微生物群保护宿主免受入侵 病原体（定殖抗性）和限制病原体扩张。丙酸盐，一种短链脂肪酸 由肠道微生物群的成员产生，预计介导对S. Tm由 下调入侵和抑制生长。S. Tm可能具有 减轻丙酸盐的毒性作用。prpBCDE操纵子的发现，使S. Tm代谢 丙酸转化为丙酮酸，提供了对S. Tm以克服丙酸盐抑制。 然而，它仍然是未知的，在什么条件下S。Tm使用prpBCDE操纵子消除细胞内的 丙酸盐在感染过程中，宿主的炎症反应提供了电子受体，使S。Tm到 将多种营养物质代谢成碳源以支持病原体生长。我的数据显示丙酸盐 作为S的碳源。Tm，特别是在无氧呼吸期间， 存在电子受体。在初步的实验中，我确定炎症产生的电子 受体还改变S.入侵机器。因此，在本发明中， 炎症衍生的电子受体可以提供S。有机会消除Tm的抑制作用 丙酸盐和燃料的增长在感染。事实上，我的初步研究表明，丙酸代谢 效益S. Tm作为S.在小鼠中，Tm比prpC突变株具有生长优势 S. Tm肠胃炎。因此，该建议的中心假设是S。Tm代谢 丙酸在发炎的肠道，以调节其入侵和支持其管腔生长，最终使这 病原体克服丙酸盐依赖性定殖抗性。为了验证这个假设，我将使用 肠道微生物群的肠道成员和S. Tm突变株沿着有细菌- 自由和传统的小鼠模型，探讨如何S。在感染过程中，Tm与丙酸盐竞争。 目标1中提出的实验将确定丙酸盐是否用作燃料S的碳源。Tm增长 体外和体内。在目标2中，我将确定丙酸是否需要肠道炎症和无氧呼吸 代谢对S.感染期间的Tm。目的3将研究丙酸代谢不仅 通过在呼吸过程中提供碳源来促进生长，但通过向S.以减少入侵。如果 成功，这项研究将挑战短链脂肪酸抑制沙门氏菌生长的教条， 直觉本项目将描述S. Tm通过代谢这种物质来减轻丙酸盐的有害影响， 代谢产物转化为可用的碳源来促进生长。预期的发现将使人们更深入地了解 这种细菌病原体使用一种新的机制来逃避肠道微生物群并建立感染。