Apolipoprotein A5 and Gallstone Formation

载脂蛋白 A5 和胆结石形成

• 批准号: 9914001
• 负责人: DAVID Q WANG
• 金额: $ 37.58万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-20 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9914001
• 关键词: APOA5 gene; Adult; Affect; American; Animals; Apolipoproteins; Automobile Driving; Bile fluid; Biliary; Biliary Sludge; Chemicals; Cholelithiasis; Cholesterol; Cholesterol Homeostasis; Crystallization; Curiosities; Data; Dependovirus; Development; Diet; Digestive System Disorders; Disease; Equilibrium; Family; Gallbladder; Gallbladder Emptying; Gel; Gene Transfer; Goals; Growth; Hepatic; Hepatobiliary; Human; Hyperlipidemia; Hypertriglyceridemia; Impairment; Insulin Resistance; Knowledge; Left; Liquid substance; Literature; Liver; Liver diseases; Mediating; Metabolic Diseases; Metabolic syndrome; Mission; Molecular; Mucins; Mus; Obesity Epidemic; Pathogenesis; Pathway interactions; Plasma; Play; Predisposition; Prevalence; Preventive Intervention; Proteins; Published Comment; Rattus; Regulation; Research; Role; Site; Solid; Solubility; Testing; Text; Therapeutic Intervention; Time; Transgenic Mice; Triglyceride Metabolism; United States National Institutes of Health; Vesicle; Wild Type Mouse; base; cell motility; crystallinity; experimental study; extracellular; gallstone disease; innovation; insight; liver-specific protein; member; novel; overexpression; physical state; response; social; unilamellar vesicle

Abstract Cholesterol gallstone disease is one of the most prevalent digestive diseases and affects 12% of American adults, leading to a considerable financial and social burden in the USA. Discovered in 2001, apolipoprotein A5 (apoA5) is a new member of the apolipoprotein family and is synthesized exclusively in the liver. Although its plasma concentration is extremely low (114-258 ng/mL), humans and mice lacking functional apoA5 develop severe hypertriglyceridemia. We found recently that apoA5, a liver-specific protein, is also secreted into bile in mice and rats. This novel discovery greatly stimulates our curiosity to investigate whether apoA5 plays a previously unrecognized and critical role in biliary cholesterol homeostasis and gallstone formation. Our preliminary data show for the first time that: (i) apoA5 is secreted into bile and is associated solely with vesicles, but not micelles, in bile of wild-type mice. Hepatic expression and bile concentrations of apoA5 are significantly reduced in the lithogenic state. (ii) ApoA5 plays a pivotal role in cholesterol solubility in bile by changing the physical state of cholesterol carriers. (iii) The absence of apoA5 in bile disrupts biliary cholesterol homeostasis by promoting the aggregation and fusion of unilamellar vesicles to form unstable multilamellar vesicles, leading to rapid cholesterol crystallization. (iv) The lack of apoA5 in bile impairs gallbladder emptying and refilling, promoting the accumulation of excess mucin gel and the growth and agglomeration of solid cholesterol crystals into microlithiasis. (v) Overexpression of APOA5 in the liver reduces susceptibility to gallstones in human APOA5 transgenic mice, even fed a lithogenic diet. Based on these novel findings, we hypothesize that apoA5 plays a critical role in biliary cholesterol homeostasis, and its deficiency greatly enhances cholelithogenesis by promoting hepatic cholesterol hypersecretion, reducing cholesterol solubility in bile, and impairing gallbladder motility function. We further propose that there are both extracellular (in bile) and intracellular (in the liver and gallbladder) roles for apoA5 in increasing gallstone formation. To test the hypothesis, we will investigate the mechanisms underlying the lithogenic roles of apoA5 deficiency in disrupting cholesterol metabolism in the bile, liver and gallbladder, thereby enhancing cholelithogenesis. In addition, we will explore whether adeno-associated virus 2/8 (AAV2/8)-mediated gene transfer of the human APOA5 protects against gallstone formation by restoring normal hepatic and biliary cholesterol metabolism. After completing the proposed studies, our results will likely present a new view on how apoA5 regulates biliary cholesterol metabolism and will develop novel concepts to elucidate the critical roles of apoA5 in driving the initiation of supersaturated bile and cholesterol crystallization, two critical steps in the earliest stage of gallstone formation. We are confident that the successful completion of this project will provide novel insight into the mechanisms of elucidating the vital extracellular and intracellular roles of apoA5 in the regulation of hepatic and biliary cholesterol metabolism and the pathogenesis of gallstones.

抽象的 胆固醇胆石病是最常见的消化系统疾病之一，影响 12% 的美国人 成年人，给美国带来了相当大的经济和社会负担。 2001 年发现载脂蛋白 A5 (apoA5) 是载脂蛋白家族的新成员，仅在肝脏中合成。虽然其 血浆浓度极低（114-258 ng/mL），人类和小鼠缺乏功能性 apoA5 严重的高甘油三酯血症。我们最近发现apoA5，一种肝脏特异性蛋白，也分泌到胆汁中 小鼠和大鼠。这一新发现极大地激发了我们研究apoA5是否发挥作用的好奇心。 以前未被认识到的在胆汁胆固醇稳态和胆结石形成中的关键作用。我们的 初步数据首次表明： (i) apoA5 分泌到胆汁中，并且仅与 野生型小鼠胆汁中存在囊泡，但没有胶束。 apoA5 的肝脏表达和胆汁浓度为 在成岩状态下显着减少。 (ii) ApoA5 通过以下方式对胆汁中胆固醇的溶解度发挥关键作用： 改变胆固醇携带者的身体状态。 (iii) 胆汁中缺乏 apoA5 会破坏胆汁胆固醇 通过促进单层囊泡的聚集和融合形成不稳定的多层来实现稳态 囊泡，导致胆固醇快速结晶。 (iv) 胆汁中缺乏 apoA5 会损害胆囊排空 并补充，促进多余粘蛋白凝胶的积累和固体的生长和结块 胆固醇结晶成微石症。 (v) APOA5 在肝脏中的过度表达可降低对以下疾病的易感性 人类 APOA5 转基因小鼠的胆结石，甚至喂食生石饮食。基于这些新颖的发现，我们 假设 apoA5 在胆汁胆固醇稳态中发挥关键作用，及其缺陷 通过促进肝脏胆固醇过度分泌，大大增强胆石生成，减少 胆固醇在胆汁中的溶解度，损害胆囊蠕动功能。我们进一步建议，有 apoA5 在增加细胞外（胆汁中）和细胞内（肝脏和胆囊中）的作用 胆结石形成。为了检验这个假设，我们将研究成岩作用的机制 apoA5 缺乏会扰乱胆汁、肝脏和胆囊中的胆固醇代谢，从而增强 胆石生成。此外，我们还将探讨腺相关病毒2/8（AAV2/8）介导的基因是否 人 APOA5 的转移通过恢复正常的肝脏和胆道来防止胆结石形成 胆固醇代谢。完成拟议的研究后，我们的结果可能会提出新的观点 apoA5 如何调节胆汁胆固醇代谢并将开发新概念来阐明关键 apoA5 在驱动过饱和胆汁和胆固醇结晶的启动中的作用，这两个关键步骤 胆结石形成的最早阶段。我们相信，该项目的顺利完成将 为阐明 apoA5 重要的细胞外和细胞内作用的机制提供新的见解 调节肝脏和胆道胆固醇代谢以及胆结石的发病机制。