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Defining the Intracellular Growth Niche of Foodborne Listeria monocytogenes

定义食源性单核细胞增生李斯特菌的细胞内生长生态位

基本信息

批准号：
10113535
负责人：
SARAH E. F. D'ORAZIO
金额：
$ 22.95万
依托单位：
UNIVERSITY OF KENTUCKY
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-03-01 至 2024-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10113535
关键词：
Anatomy Bacteremia Bacteria Biological Assay Blood Bypass C57BL/6 Mouse Cell surface Cells Colon Cytosol Data Defect Dendritic Cells Dependence Disease Outbreaks E-Cadherin Eating Elderly Environment Epithelial Event Exposure to Feces Flow Cytometry Food Food Contamination Food Supply Gastroenteritis Gastrointestinal tract structure Gentamicins Goals Growth Gut Mucosa Hospitalization Immune Immune system Immunoassay In Vitro Incidence Individual Infection Ingestion Innate Immune Response Interleukin-12 Interleukin-18 Interleukin-6 Intestinal Diseases Intestines Intravenous Invaded Knowledge Lamina Propria Large Intestine Lead Life Ligation Listeria monocytogenes Listeriosis M cell Measures Mediating Meningoencephalitis Minor Modeling Mus Myelogenous Myeloid Cells Neuraxis Phagocytes Phase Population Process Production Resistance Route Sepsis Septicemia Severities Severity of illness Small Intestines Stains Submucosa Surface Symptoms Systemic infection Therapeutic Intervention Time Tissues Virulence Work cell type cytokine cytosolic receptor design draining lymph node enteric infection experience experimental study extracellular feeding foodborne foodborne infection foodborne pathogen human disease ileum in vivo macrophage mesenteric lymph node monocyte mortality mouse model neonate pathogen prevent response transmission process

项目摘要

Ingestion of Listeria monocytogenes (Lm)-contaminated food results in human disease ranging in severity from mild, self-limiting gastroenteritis to life-threatening septicemia and meningoencephalitis. The specific factors that influence disease severity are not well understood, and our knowledge of the intestinal phase of listeriosis, in particular, is severely limited. We recently developed a mouse model of foodborne infection to study the interaction of Lm with intestinal innate immune cells. In preliminary studies, we found that the majority of Lm in the gut were extracellular. This was an unexpected result, because intracellular growth and spread from cell-to-cell without encountering the extracellular milieu are generally regarded as the primary virulence strategies for these facultative intracellular bacteria. LplA1-deficient Lm that were unable to replicate intracellularly could readily invade the gut mucosa and establish infection in the underlying lamina propria, but did not persist as well as wildtype Lm, and by three days post-infection had a severe defect in spreading to the mesenteric lymph nodes (MLN). This suggests that intracellular growth is not required for the initial stages of intestinal infection, but replication in some as-yet-unidentified cell type in the gut becomes increasingly more important as the infection proceeds. Multicolor flow cytometry can discriminate eight different subsets of myeloid-derived phagocytes that are unique to the gut. Preliminary data provided here verified that intestinal tissue contained at least one cell type that could support intracellular growth of Lm, and ruled out Ly6Chi monocytes and all three subsets of conventional dendritic cells as the intracellular niche. The primary goal of this proposal is to identify the cell type(s) in the gut that support intracellular growth of Lm and to define the innate immune response of intestinal cell types that that interact primarily with either intracellular or extracellular Lm. We hypothesize that Lm initially interact primarily with cell types that that they cannot efficiently invade or survive in, and that later in the course of infection, the bacteria shift to a cell type that serves as a protected intracellular growth niche.!In Aim 1, four candidate intestinal myeloid cell types will be sort purified, infected directly ex vivo and assayed for both intracellular localization and replication. In Aim 2, flow cytometry will be used to identify Lm-associated cells in the lamina propria and submucosa of the ileum and colon as well as the MLN that drain each of these tissues (SI-MLN and LI-MLN) to track the fate of Lm that invade the gut mucosa in mice. In Aim 3, we will define the initial response of all eight subsets of intestinal myeloid cells by measuring the production of cytokines known to be triggered by either host cell surface bound or cytosolic receptors. These exploratory studies will fill a key knowledge gap in the field by defining the early events that occur in the gut during foodborne transmission of Lm. !

摄入单核细胞增生李斯特菌（Lm）污染的食物会导致严重程度不等的人类疾病