Host Response

腹泻病是5岁以下儿童的主要杀手。这些感染代表了微生物和宿主之间的平衡。宿主对肠道感染的反应包括在肠上皮和粘膜/全身免疫系统中观察到的反应。该项目将使用小鼠肠道组织和人类临床标本来检查这两种类型的反应。具体目标1将表征安装在Ussing室和微卡扣孔中的小鼠上皮组织对志贺氏菌和肠致病性E.大肠杆菌（EPEC），特别强调肠屏障功能，短路电流和上皮细胞因子的产生。将对特定毒力因子缺陷的几种同基因突变体进行检测，以确定这些因子对观察到的反应的贡献。与将使用野生型小鼠和各种细菌突变体的目标1相反，特定目标2将使用野生型细菌和各种突变小鼠品系来确定特异性模式识别受体（PRR）在肠粘膜对志贺氏菌和EPEC的反应中的作用。肠组织将从MyD 88、TLR 4、TLR 5、Nod 1、Nod 2、PAR 2或肥大细胞缺陷的野生型和敲除小鼠中分离，并离体暴露于志贺氏菌和EPEC。比较不同小鼠品系的肠粘膜功能和免疫应答，将表征这些PRR在EPEC和志贺氏菌感染中的作用。具体目标3将检查来自流行国家的儿童中与志贺氏菌和EPEC感染相关的胃肠道中的适应性免疫和免疫标记物。将对GEMS研究中记录的志贺氏菌和EPEC感染儿童的粪便标本进行病原体特异性适应性应答分析，包括志贺氏菌和EPEC抗原特异性sIgA、伊加和IgG。还将分析粪便细胞因子和炎症分子，并寻求与临床结局的相关性。

Diarrheal diseases are a major killer of children under the age of 5. These infections infections represent a balance between the microbe and the host. Host responses to enteric infections include those seen in the intestinal epithelium and in the mucosal/systemic immune system. This project will examine both types of responses using mouse intestinal tissue and human clinical specimens. Specific Aim 1 will characterize the response of mouse epithelial tissue mounted in Ussing chambers and microsnapwells to infection with Shigella and enteropathogenic E. coli (EPEC) with particular emphasis on intestinal barrier function, short circuit current, and epithelial cytokine production. Several isogenic mutants defective in specific virulence factors will be tested to determine the contribution of these factors to the responses seen. In contrast to Aim 1, which will employ wild type mice and various bacterial mutants, Specific Aim 2 will employ wild type bacteria and various mutant mouse strains to establish the role of specific pattern recognition receptors (PRRs) in the intestinal mucosal response to Shigella and EPEC. Intestinal tissue will be isolated from wild type and knock out mice deficient in MyD88, TLR4, TLR5, Nodi, Nod2, PAR2 , or mast cells and exposed ex vivo to Shigella and EPEC. Comparison of the intestinal mucosal function and immune responses in the different mouse lines will characterize the role of these PRRs in infections due to EPEC and Shigella. Specific Aim 3 will examine adaptive immunity and immunological markers in the Gl tract that are associated with Shigella and EPEC infection in children from endemic countries. Stool specimens from children with documented Shigella and EPEC infections in the GEMS study will be analyzed for pathogen specific adaptive responses including sIgA, IgA, and IgG specific for Shigella and EPEC antigens. Fecal cytokines and inflammatory molecules will also be analyzed and correlations sought with clinical outcomes.