Hepatic survival and population dynamics of extraintestinal pathogenic Escherichia coli

肠外致病性大肠杆菌的肝脏存活和种群动态

• 批准号: 10647846
• 负责人: Karthik Hullahalli
• 金额: $ 3.55万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10647846
• 关键词: Acceleration; Bacteremia; Bacteria; Bacterial Genes; Blood Circulation; Cardiovascular system; Cell Wall; Cells; Circulation; Clinical; Clonal Expansion; Clonality; Disease; Disparate; Dose; E. coli bacteremia; Escherichia coli; Etiology; Genes; Genetic; Hepatic; Homeostasis; Host Defense; Human; Image; Immune; Immune system; Individual; Infection; Intestines; Kinetics; Knowledge; Kupffer Cells; Libraries; Lipopolysaccharides; Liver; Macrophage; Maps; Membrane; Methods; Monitor; Mus; Neonatal meningitis; Organ; Pathogenesis; Pathogenicity; Pathway interactions; Polysaccharides; Population; Population Analysis; Population Dynamics; Role; Sampling; Sentinel; Sepsis; Spleen; Systemic infection; Time; Tissues; Urinary tract infection; Virulence Factors; bacterial fitness; cell envelope; cell type; firewall; fitness; genome-wide; in vivo; insight; intrahepatic; intravenous injection; microbial; monocyte; mortality; mouse model; mutant; neutrophil; novel therapeutic intervention; pathogen; pathogenic Escherichia coli; population based; recruit; systemic inflammatory response; therapeutic development; transmission process; transposon sequencing

ABSTRACT Extraintestinal Pathogenic Escherichia coli (ExPEC) comprise a broad group of E. coli isolates that cause disease outside of the intestine and are among the most common causes of clinical bacteremia in humans. Most bacteria that gain access to the circulatory system are captured and killed by tissue-resident macrophages in the liver. In contrast to related commensal and intestine-restricted pathogenic E. coli, ExPEC isolates possess mechanisms to survive longer within these hepatic defenses. To uncover genes underlying such mechanisms, we performed a genome-scale transposon insertion sequencing screen on ExPEC isolated from murine livers following intravenous injection of mice with an ExPEC transposon insertion library. This screen uncovered a core set of genes required for optimal ExPEC fitness in the liver, ~90% of which encode components or regulators of the cell envelope. Unexpectedly, analysis of the population-level distribution of transposon-insertion mutants revealed that a random subset of the bacteria within the liver expands clonally. Together, these observations underlie the two central hypotheses that will be explored in this proposal: 1) ExPEC pathways that control distinct cell envelope homeostasis axes protect bacteria against liver macrophages to maintain bacterial survival, and 2) interactions between liver macrophages and specific bacterial genes that support intra-hepatic survival govern how the pathogen is distributed within the host during clearance. Findings from the proposed studies, which rely on both pathogen- and host-centric approaches, will provide knowledge of how ExPEC survive within and are cleared from extraintestinal organs. Ultimately, these fundamental insights may assist in the development of therapeutic strategies to accelerate clearance of systemic infections.

抽象的 肠外致病性大肠杆菌 (ExPEC) 包含一大类大肠杆菌分离株，可导致 肠道外的疾病，是人类临床菌血症的最常见原因之一。最多 进入循环系统的细菌被组织驻留的巨噬细胞捕获并杀死 肝脏。与相关共生和肠道限制性致病性大肠杆菌相比，ExPEC 分离株具有 在这些肝脏防御系统中存活更长时间的机制。为了揭示这种机制背后的基因， 我们对从小鼠肝脏分离的 ExPEC 进行了基因组规模的转座子插入测序筛选 向小鼠静脉注射 ExPEC 转座子插入文库后。这个画面揭开了一个核心 肝脏中最佳 ExPEC 适应性所需的一组基因，其中约 90% 编码以下成分或调节因子 细胞膜。出乎意料的是，转座子插入突变体的群体水平分布分析 揭示了肝脏内细菌的随机子集进行克隆扩张。综合起来，这些观察结果 构成本提案将探讨的两个中心假设的基础：1）控制不同的 ExPEC 途径 细胞包膜稳态轴保护细菌免受肝脏巨噬细胞的侵害，以维持细菌的生存，以及 2）肝脏巨噬细胞和支持肝内生存的特定细菌基因之间的相互作用 清除过程中病原体如何在宿主体内分布。拟议研究的结果依赖于 以病原体和宿主为中心的方法，将提供有关 ExPEC 如何在其中生存和生存的知识 从肠外器官中清除。最终，这些基本见解可能有助于开发 加速清除全身感染的治疗策略。