Mechanisms of Microbial Competition During Salmonella Infection

沙门氏菌感染期间微生物竞争的机制

• 批准号: 10600681
• 负责人: Lauren Christine Radlinski
• 金额: $ 6.95万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-12-01 至 2025-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10600681
• 关键词: Acids; Amino Acids; Animal Model; Antibiotic Resistance; Antibiotic Therapy; Antibiotics; Attenuated; Biochemical Reaction; Buffers; Carboxy-Lyases; Catabolism; Cataloging; Cell Death; Communities; Consumption; Cytoplasm; Cytosol; Dietary Fiber; Discipline; Disease; Ecosystem; Engineering; Enterobacteriaceae; Environment; Family; Fermentation; Glean; Gnotobiotic; Goals; Growth; Homeostasis; Host Defense; Hypoxia; Immunocompromised Host; In Vitro; Individual; Infection; Inflammation; Inflammatory Response; Intestines; Invaded; Knowledge; Large Intestine; Link; Mediating; Metabolic Pathway; Microbe; Modeling; Modification; Mus; Nutrient; Nutritional; Outcome; Pathway interactions; Patients; Play; Predisposition; Production; Protons; Public Health; Reaction; Research; Resistance; Role; Salmonella; Salmonella enterica; Salmonella infections; Salmonella typhimurium; Secure; Supplementation; Testing; Toxic effect; Treatment Failure; Type III Secretion System Pathway; Virulence; Virulence Factors; Volatile Fatty Acids; Work; acid stress; antimicrobial; bacterial genetics; biological adaptation to stress; colonization resistance; commensal microbes; dysbiosis; enteric infection; enteric pathogen; gastrointestinal; gastrointestinal infection; gut colonization; gut homeostasis; high risk; improved; in vivo; innovation; intestinal epithelium; metabolomics; microbial; microbial community; microbiome; microbiota; microorganism; mouse model; novel therapeutic intervention; pH Homeostasis; pathogen; prevent; programs

PROJECT SUMMARY The microbiota is a critical frontline barrier that protects the host from invading microorganisms and keeps resident opportunists in check. Frank pathogens such as Salmonella enterica serovar Typhimurium (STm), however, are adept at overcoming microbiota-mediated colonization resistance to cause dysbiosis and disease. Under homeostasis, antimicrobial short-chain fatty acids (SCFAs) produced by the microbiota protect the host by restricting pathogen replication through cytosol acidification. During infection, STm uses its type III secretion systems (T3SS) to trigger an inflammatory response that depletes SCFA-producing commensals. Current paradigm holds that the depletion of SCFA-producing species is a pre-requisite for luminal STm expansion. However, using an antibiotic-naïve mouse model we have observed that STm blooms 1000-fold 3-4 days prior to the onset of overt inflammation when SCFAs are abundant and the community composition of the microbiota is undisturbed. This implies that STm employs an as-of-yet undescribed strategy to restore pH homeostasis and grow in the presence of SCFAs during gastrointestinal colonization. Our preliminary findings suggest that proton- consuming metabolic pathways, including the amino acid decarboxylases CadA and SpeF, alleviate SCFA growth inhibition in vitro and are required for full virulence in vivo, yet it is unclear whether these pathways specifically mediate growth in the presence of SCFAs within the host, or how STm secures the metabolites that fuel these pathways in the nutrient-restricted gastrointestinal environment. I hypothesize that during colonization of the gastrointestinal tract, STm uses its T3SS to obtain host-derived amino acids that fuel proton-consuming reactions and restore pH homeostasis in the presence of commensal-produced SCFAs. The objective of this application is to elucidate how STm adapts to the intestinal environment and to use this understanding to develop my own independent research program that investigates how enteric pathogens overcome intrinsic protective barriers so that we may uncover new therapeutic approaches for bolstering colonization resistance in high-risk patients. In AIM1 we will assess the contribution of proton-consuming metabolic pathways in restoring pH homeostasis and growth in the presence of SCFAs in vitro, and investigate the role these pathways play in mediating early ecosystem invasion in vivo using conventional and gnotobiotic animal models. In AIM2 we will use bacterial genetics, murine infection models, and metabolomics to determine how STm uses its virulence factors to engineer a new gastrointestinal niche that supports dysbiotic Enterobacteriaceae expansion under homeostatic conditions. This mechanistic approach to microbiota research will provide causal links between pathogen-mediated environmental remodeling and changes in microbial growth conditions that cannot be gleaned from solely cataloging bacterial species. Successful completion of this work will reveal opportunities to enhance innate host defenses by identifying and targeting the metabolic pathways enteric pathogens use to overcome colonization resistance.

项目摘要 微生物群是保护宿主免受微生物入侵的关键前线屏障， 居住机会在检查。弗兰克病原体，如沙门氏菌肠血清型鼠伤寒（STm）， 然而，它们擅长克服微生物群介导的定殖抗性以引起生态失调和疾病。 在体内平衡下，由微生物群产生的抗微生物短链脂肪酸（SCFA）保护宿主 通过细胞质酸化限制病原体复制。在感染过程中，STm利用其III型分泌物 系统（T3 SS）触发炎症反应，耗尽产生SCFA的共生体。电流 这种范式认为，SCFA产生物质的消耗是管腔STm扩增的先决条件。 然而，使用未接种过疫苗的小鼠模型，我们观察到STm在接种前3-4天开花1000倍。 当SCFAs丰富时， 没有受到干扰这意味着STm采用了一种尚未描述的策略来恢复pH稳态， 在胃肠道定植期间在SCFA存在下生长。我们的初步发现表明质子- 消耗代谢途径，包括氨基酸脱羧酶CadA和SpeF，可以缓解SCFA 体外生长抑制，体内完全毒力所需，但目前尚不清楚这些途径是否 在宿主内存在SCFAs的情况下特异性介导生长，或者STm如何确保 在营养受限的胃肠道环境中为这些途径提供燃料。我假设在殖民时期 在胃肠道中，STm使用其T3 SS获得宿主衍生的氨基酸，这些氨基酸为质子消耗提供燃料。 反应和恢复pH稳态的存在下，海藻酸钠生产的SCFA。 本申请的目的是阐明STm如何适应肠道环境，并使用 这一认识，以发展我自己的独立研究计划，调查如何肠道病原体 克服内在的保护屏障，以便我们可以发现新的治疗方法， 高风险患者的耐药性。在AIM 1中，我们将评估质子消耗的贡献 代谢途径恢复pH稳态和生长的SCFAs在体外的存在下，并调查 这些途径在使用常规和非菌生物介导体内早期生态系统入侵中所起作用 动物模型在AIM 2中，我们将使用细菌遗传学，小鼠感染模型和代谢组学来确定 STm如何利用其毒力因子设计一种新的支持微生态失调的胃肠道生态位 稳态条件下肠杆菌科细菌的扩增。这种微生物研究的机械方法 将提供病原体介导的环境重塑和微生物生长变化之间的因果关系 这些条件不能仅仅通过细菌物种的分类来收集。顺利完成这项工作 将揭示通过识别和靶向代谢途径来增强宿主先天防御的机会 肠道病原体用于克服定植抗性。