Regulation of Intestinal Epithelial Tight Junction Barrier

肠上皮紧密连接屏障的调节

• 批准号: 8244940
• 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 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8244940
• 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.

描述(由申请人提供)： 摘要肠上皮紧密连接(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、非甾体抗炎药相关性肠炎和感染性腹泻综合征)和全身炎症(包括酒精性肝病、中暑、失血性休克和危重疾病)的关键致病因素。有缺陷的肠道TJ屏障允许肠腔抗原跨上皮屏障的细胞旁渗透，导致肠道和全身循环中细菌内毒素的局部炎症反应，最终导致全身炎症反应和终末器官损害。虽然肠源性脂多糖在肠道炎症和全身炎症反应的发病机制中起着关键作用，但它们在破坏肠上皮紧密连接屏障中的作用尚不清楚。我们的初步研究表明，生理相关浓度(1~1 ng/ml)的脂多糖(LPS)可引起肠上皮细胞通透性增加，与细胞凋亡或细胞死亡无关。这项拨款提案的主要目标是利用体外(由滤器生长的Caco-2肠道上皮单层组成)和体内(再循环肠道灌流)小鼠模型系统，阐明介导内毒素诱导的肠道TJ通透性增加的细胞内和分子机制。我们的初步数据表明，内毒素诱导的肠上皮细胞TJ通透性增加的部分机制是：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。根据我们的初步研究，我们假设生理浓度的内毒素通过TLR-4信号转导通路激活MLCK基因和MLCK调节的肠上皮TJ屏障开放，从而诱导肠上皮细胞TJ通透性增加。本研究的目的是：1)阐明TLR-4信号转导通路在内毒素引起的肠上皮通透性增加中的作用；2)阐明内毒素引起肠上皮通透性增加的分子过程；3)阐明内毒素引起的在体肠通透性增加的机制。