Dietary Fat in Ethanol-Induced Intestinal Barrier Dysfunction in ALD

乙醇引起的酒精性肝病肠屏障功能障碍中的膳食脂肪

• 批准号: 8517522
• 负责人: IRINA A. KIRPICH
• 金额: $ 16.57万
• 依托单位: UNIVERSITY OF LOUISVILLE
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8517522
• 关键词: Acetaldehyde; Alcoholic Liver Diseases; Alcoholic beverage heavy drinker; Alcohols; Animal Model; Attenuated; Blood; Caco-2 Cells; Chronic; Development; Diet; Dietary Fats; Endotoxemia; Endotoxins; Epithelial; Epithelial Cells; Ethanol; Event; Fatty Acids; Fatty acid glycerol esters; Functional disorder; Genetic; Goals; Immune system; In Vitro; Individual; Inflammation; Inflammatory; Inflammatory disease of the intestine; Injury; Interleukin-1; Intestines; Joints; Lead; Linoleic Acids; Lipopolysaccharides; Liver; Liver diseases; Mediating; Molecular; Morbidity - disease rate; Myosin Light Chain Kinase; NF-kappa B; Organ; Oxidative Stress; Pathogenesis; Permeability; Play; Polyunsaturated Fatty Acids; Preventive; Production; Proteins; Rodent; Role; Saturated Fatty Acids; TNF gene; Therapeutic; Tight Junctions; Tissues; Transcriptional Activation; United States; Unsaturated Fats; Unsaturated Fatty Acids; Work; alcohol effect; base; cell type; chronic alcohol ingestion; claudin-1 protein; cofactor; cytokine; in vitro Model; in vivo; liver injury; mortality; mouse model; new therapeutic target; novel; novel therapeutic intervention; occludin; prevent

DESCRIPTION (provided by applicant): This application will evaluate Gut-Liver and Diet-Alcohol interactions with respect to the critical role of intestinal barrier integrity/function in he development and progression of alcoholic liver disease (ALD). ALD remains one of the leading causes of liver diseases and a major cause of morbidity and mortality in the United States and worldwide. Why some heavy drinkers develop ALD and other are spared is unclear (we postulate dietary effects-see below). Gut-derived lipopolysaccharide (LPS) plays a crucial role in the development of ALD. Increased intestinal permeability resulting from the disruption of intestinal integrity is a major cause of alcohol-induced endotoxemia. Dietary fat is an important cofactor for the development of ALD. It has been shown that diets enriched in saturated fatty acids protect against alcohol-induced liver disease in rodents, whereas dietary polyunsaturated fatty acids (e.g. linoleic acid, LA) promote liver damage. Our working hypothesis is that dietary LA potentiates pro-oxidative and pro-inflammatory effects on intestinal epithelial cells with consequent NF-kB activation. These events lead to alterations of intestinal tight junctions through an MLCK-dependent mechanism and contribute to the ethanol-associated disruption of intestinal integrity. We hypothesize that the combined deleterious effects of LA and EtOH on intestinal barrier integrity occur through a common NF-kB-MLCK-mediated mechanism. Increased gut permeability leads to elevated blood endotoxemia and consequent liver injury. Thus, inhibition of MLCK will attenuate intestinal tight junction disruption, decrease gut leakines and blood endotoxemia, and attenuate ethanol/dietary linoleic acid induced liver damage. The Specific Aims of our application are: 1. To determine: a) if linoleic acid induces oxidative stress activates NF-kB and increases pro-inflammatory cytokine production in Caco-2 cells, an in vitro model of the intestinal epithelial barrier; b) if linoleic acid enhances ethanol- mediated disruptin of intestinal barrier integrity by deregulation and redistribution of the major tight junctions proteins through an NF-kB-MLCK-mediated mechanism, and if this effect is additive or synergistic. 2. To determine: a) whether dietary linoleic acid potentiates intestinal oxidative stress and promotes intestinal inflammation through NF-kB activation in an animal model of ALD; b) whether dietary linoleic acid-mediated intestinal inflammation contributes to ethanol-associated intestinal tight junction dysfunction through the MLCK-mediated mechanism in vivo; and c) if pharmacological inhibition/genetic deletion of MLCK can attenuate tight junction alterations, decrease gut permeability and blood endotoxemia, and consequently attenuate liver injury in a mouse model of ALD. Dietary modulation may represent a novel preventive/therapeutic approach in ALD, and MLCK could be a specific novel therapeutic target.

描述（由申请人提供）：本申请将评估肠道-肝脏和饮食-酒精之间的相互作用，了解肠道屏障完整性/功能在酒精性肝病（ALD）发生和进展中的关键作用。 ALD 仍然是肝脏疾病的主要原因之一，也是美国和世界范围内发病和死亡的主要原因。为什么一些酗酒者会患上酒精性肝病，而其他人却能幸免，目前尚不清楚（我们假设饮食影响 - 见下文）。肠源性脂多糖（LPS）在 ALD 的发展中起着至关重要的作用。肠道完整性破坏导致肠道通透性增加是酒精性内毒素血症的主要原因。膳食脂肪是 ALD 发生的重要辅助因素。研究表明，富含饱和脂肪酸的饮食可以预防啮齿动物因酒精引起的肝病，而饮食中的多不饱和脂肪酸（例如亚油酸，LA）则会促进肝损伤。我们的工作假设是，饮食中的 LA 可增强对肠上皮细胞的促氧化和促炎症作用，从而激活 NF-kB。这些事件通过 MLCK 依赖性机制导致肠道紧密连接的改变，并导致与乙醇相关的肠道完整性破坏。我们假设 LA 和 EtOH 对肠道屏障完整性的联合有害作用是通过共同的 NF-kB-MLCK 介导机制发生的。肠道通透性增加导致血液内毒素血症升高并随之而来的肝损伤。因此，抑制 MLCK 将减轻肠道紧密连接破坏，减少肠道渗漏和血液内毒素血症，并减轻乙醇/膳食亚油酸诱导的肝损伤。我们应用的具体目标是： 1. 确定：a) 亚油酸是否会诱导氧化应激激活 NF-kB 并增加 Caco-2 细胞（肠上皮屏障的体外模型）中促炎细胞因子的产生； b) 亚油酸是否通过 NF-kB-MLCK 介导的机制解除主要紧密连接蛋白的调节和重新分布，从而增强乙醇介导的肠屏障完整性破坏，并且这种作用是否是相加的或协同的。 2. 确定：a) 在 ALD 动物模型中，膳食亚油酸是否会通过激活 NF-kB 来增强肠道氧化应激并促进肠道炎症； b) 膳食亚油酸介导的肠道炎症是否通过体内 MLCK 介导的机制导致乙醇相关的肠道紧密连接功能障碍； c) MLCK 的药理抑制/基因缺失是否可以减弱紧密连接的改变，降低肠道通透性和血液内毒素血症，从而减轻 ALD 小鼠模型的肝损伤。饮食调节可能代表 ALD 的一种新型预防/治疗方法，而 MLCK 可能是一种特定的新型治疗靶点。