Regulation of Intestinal Epithelial Tight Junction Barrier

肠上皮紧密连接屏障的调节

• 批准号: 8141671
• 负责人: THOMAS Y MA
• 金额: --
• 依托单位: ALBUQUERQUE VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8141671
• 关键词: Adult Respiratory Distress Syndrome; Alcoholic Liver Diseases; Antigens; Apoptosis; Applications Grants; Bacterial Antigens; Biological Models; Blood Circulation; Body Weight; Catalytic Domain; Celiac Disease; Cell Death; Cessation of life; Critical Illness; Crohn' s disease; Data; Development; Disease; Endotoxins; Enterocytes; Epithelial; Epithelial Cells; Funding; Gene Expression; Genes; Goals; Heat Stroke; Hemorrhagic Shock; In Vitro; Inflammatory; Inflammatory Response; Inflammatory disease of the intestine; Intestines; Laboratory Research; Lateral; Lipopolysaccharides; MAPK14 gene; Mediating; Mediator of activation protein; Membrane; Molecular; Mus; Myosin Light Chain Kinase; Necrotizing Enterocolitis; Non-Steroidal Anti-Inflammatory Agents; Organ; Organ failure; Pathogenesis; Pathway interactions; Perfusion; Permeability; Phosphotransferases; Physiological; Physiology; Play; Process; Reaction; Recycling; Regulation; Research; Role; Services; Signal Transduction; Signal Transduction Pathway; Small Interfering RNA; Stream; Syndrome; Systemic disease; Testing; Therapeutic; Tight Junctions; Time; Tissues; Ulcerative Colitis; Up-Regulation; abstracting; acute pancreatitis; base; enteritis; gastrointestinal; in vitro Model; in vivo; intraperitoneal; knock-down; mRNA Expression; monolayer; mouse model; prevent; protein expression; seal; toll-like receptor 4

DESCRIPTION (provided by applicant): Abstract Defective intestinal epithelial tight junction (TJ) barrier has been postulated to be a key pathogenic factor in variety of inflammatory diseases of the gut (including Crohn's disease, ulcerative colitis, necrotizing enterocolitis, NSAID associated enteritis, and infectious diarrheal syndromes) and systemic inflammatory conditions (including alcoholic liver disease, heat stroke, hemorrhagic shock, and critically ill). The defective intestinal TJ barrier allows paracellular permeation of luminal antigens across the epithelial barrier, leading to both local inflammatory response in the gut and systemic circulation of bacterial endotoxins culminating in systemic inflammatory response and end-organ damage. Although gut-derived lipopolysaccharides play a critical role in the pathogenesis of intestinal inflammation and systemic inflammatory response, their role in disruption of intestinal epithelial tight junction barrier remains unknown. Our preliminary studies indicated that lipopolysaccharide (LPS) at physiologically relevant concentrations (.1 to 1 ng/ml) causes an increase in intestinal epithelial TJ permeability, unrelated to apoptosis or cell death. The broad objectives of this grant proposal are to elucidate the intracellular and molecular mechanisms that mediate the LPS induced increase in intestinal TJ permeability using an-in-vitro (consisting of filter-grown Caco-2 intestinal epithelial monolayers) and in-vivo (re-cycling intestinal perfusion) murine model systems. Our preliminary data suggested that the LPS induced increase in intestinal epithelial TJ permeability was mediated in part by: 1) increase in Toll-like receptor-4 (TLR-4) expression; 2) activation of p38 kinase pathway; and 3) increase in myosin light chain kinase (MLCK) mRNA and protein expression. Based on our preliminary studies, we hypothesize that physiologically relevant concentrations of LPS induce an increase in intestinal epithelial TJ permeability via TLR-4 signal transduction cascade activation of MLCK gene and MLCK-regulated opening of the intestinal epithelial TJ barrier. The proposed specific aims are to: 1) delineate the involvement of TLR-4 signal transduction cascade in LPS induced increase in intestinal epithelial TJ permeability; 2) delineate the molecular processes involved in LPS induced increase in intestinal TJ permeability; and 3) delineate the mechanisms involved in LPS induced increase in intestinal permeability in-vivo. PUBLIC HEALTH RELEVANCE: Narrative Defective intestinal barrier or "leaky gut" allows bacterial antigens in the gut to be absorbed and induce inflammatory response. In wide variety of diseases, absorbed bacterial antigens reach systemic circulation and induce systemic inflammatory reaction, leading to multi-organ failure or death. Gut- derived bacterial antigens are important mediators of intestinal and systemic inflammatory response. The purpose of this grant application is to elucidate the pathogenic mechanisms involved in bacterial antigen induced disruption of intestinal barrier (or development of leaky gut).

描述（由申请人提供）： 摘要肠上皮细胞紧密连接（TJ）屏障缺陷被认为是多种肠道炎症性疾病（包括克罗恩病、溃疡性结肠炎、坏死性小肠结肠炎、NSAID相关性肠炎和感染性肠炎综合征）和全身性炎症性疾病（包括酒精性肝病、中暑、失血性休克和危重病）的关键致病因素。有缺陷的肠TJ屏障允许管腔抗原通过上皮屏障的细胞旁渗透，导致肠道中的局部炎症反应和细菌内毒素的全身循环，最终导致全身炎症反应和终末器官损伤。虽然肠源性脂多糖在肠道炎症和全身性炎症反应的发病机制中起着关键作用，但其在破坏肠上皮紧密连接屏障中的作用仍不清楚。我们的初步研究表明，脂多糖（LPS）在生理相关浓度（0.1至1 ng/ml）导致肠上皮TJ通透性增加，无关的细胞凋亡或细胞死亡。这项资助提案的主要目的是阐明细胞内和分子机制，介导的LPS诱导增加肠道TJ渗透性使用一个在体外（包括过滤生长的Caco-2肠上皮单层）和体内（再循环肠灌注）小鼠模型系统。我们的初步数据表明，LPS诱导的肠上皮TJ通透性增加部分介导：1）Toll样受体-4（TLR-4）表达增加; 2）p38激酶通路激活; 3）肌球蛋白轻链激酶（MLCK）mRNA和蛋白表达增加。基于我们的初步研究，我们假设生理相关浓度的LPS通过TLR-4信号转导级联激活MLCK基因和MLCK调节的肠上皮TJ屏障开放诱导肠上皮TJ通透性增加。提出的具体目标是：1）描述TLR-4信号转导级联参与LPS诱导的肠上皮TJ渗透性增加; 2）描述LPS诱导的肠TJ渗透性增加中涉及的分子过程;和3）描述LPS诱导的体内肠渗透性增加中涉及的机制。 公共卫生关系： 肠屏障缺陷或“漏肠”允许肠道中的细菌抗原被吸收并诱导炎症反应。在多种疾病中，吸收的细菌抗原进入体循环，引起全身炎症反应，导致多器官功能衰竭或死亡。肠源性细菌抗原是肠道和全身炎症反应的重要介质。本基金申请的目的是阐明细菌抗原诱导的肠屏障破坏（或肠漏发展）的致病机制。