Mechanisms of Microbial Competition During Salmonella Infection

沙门氏菌感染期间微生物竞争的机制

基本信息

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
项目类别：
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

项目摘要

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一个关键的前线障碍，可保护宿主免受侵入微生物的影响并保持居住的机会主义者。弗兰克病原体，例如沙门氏菌血清Typhimurium（STM），然而，善于克服微生物群介导的定殖耐药性以引起营养不良和疾病。在稳态下，菌群生产的抗菌短链脂肪酸（SCFA）保护宿主通过通过胞质酸化来限制病原体复制。在感染期间，STM使用其III型分泌系统（T3SS）触发炎症反应，以耗尽产生SCFA的共生。当前的范式认为，产生SCFA的物种的部署是Luminal STM扩展的先决条件。但是，使用抗生素不含的小鼠模型，我们观察到STM血液1000倍3-4天当SCFA丰富时，明显的炎症发作和微生物群的社区组成不受干扰。这意味着STM员工尚未确定恢复pH稳态和在胃肠道定殖过程中SCFA的存在下生长。我们的初步发现表明质子食用代谢途径，包括氨基酸脱羧酶CADA和SPEF，减轻了SCFA 体外抑制生长抑制作用，是体内全病毒所必需的，但尚不清楚这些途径是否存在特别是在宿主内SCFA存在的情况下的媒体增长，或者STM如何确保代谢物在营养限制的胃肠道环境中为这些途径加油。我假设在殖民期间在胃肠道中，STM使用其T3SS获得宿主衍生的氨基酸，以燃料质子消费在存在共生产生的SCFA的情况下，反应并恢复pH稳态。该应用的目的是阐明STM如何适应肠道环境并使用这种了解我自己的独立研究计划的理解，该计划调查了肠道病原体克服固有的保护障碍，以便我们可以发现加强新的治疗方法高危患者的定殖抗性。在AIM1中，我们将评估质子消费的贡献在体外SCFA存在下恢复pH稳态和生长的代谢途径，并研究这些途径在使用常规和gnotobiotic介导早期生态系统入侵体内的作用动物模型。在AIM2中，我们将使用细菌遗传学，鼠感染模型和代谢组学来确定 STM如何使用其病毒因素来设计一种支持不良生物的新胃肠道生态位肠杆菌科在稳态条件下的扩展。这种微生物群研究的机械方法将在病原体介导的环境重塑与微生物生长变化之间提供因果关系不能仅根据细菌分类而收集的条件。成功完成这项工作将通过识别和瞄准代谢途径来揭示机会来增强先天寄主的防御肠道病原体用来克服定殖抗性。