Alimentary Tract Lipids in Health and Disease

描述(申请人提供)：本申请的目的是利用生物物理和病理生理学原理以及物理、化学、生化和分子生物学技术来促进对胆汁及其两种主要功能障碍，即胆汁淤积和胆色素结石和胆固醇结石的基本了解，i)第一个目标将确定肠道和肝脏感染轮状螺杆菌和肝门氏菌这两种人类和小鼠常见的肠胆病原体是否是通过胆固醇过饱和胆汁的核化而导致胆固醇结石发病的最终共同触发因素。将对遗传易感胆结石的小鼠进行研究，结合模型和天然胆汁中胆固醇成核的体外分析，以及量化人类胆道组织中幽门螺杆菌感染的证据；ii)目的二将量化致石状态下胆管膜上磷脂酰乙醇胺三甲基化为磷脂酰胆碱的途径的活性，这可能与胆汁胆固醇的高分泌有关。第三个目标将研究并明确证明，在Slc10a2基因缺失的小鼠中，胆红素和‘黑色’色素结石的肠肝循环可导致严重的胆盐吸收不良，并确定含有共价连接胆酸(一种强大的胆红素结合剂)的未吸收水凝胶或含有β-葡萄糖苷酸酶的1-4-内酯可预防胆盐严重吸收不良。目标四将通过实验和分子动力学模拟计算出天然胆汁中结合胆红素和非结合胆红素的物理状态，并确定人胆汁中“黑色”色素胆结石形成所需的热力学条件；v)第五个目标将探索与完全肠外营养相关的胆汁淤积和色素“污泥”以及胆结石的形成，重点是肠内饥饿导致的CCK和促胰液素的缺乏。激素缺乏导致未结合胆红素的肠-肝循环，从而产生高胆红素，也导致较低的碱性肝胆汁，其中发生内源性β-葡萄糖醛酸酶对胆红素葡萄糖醛酸苷的水解和胆红素钙的沉淀。这些假设驱动的基础研究目标的结果将提供与自然系统和模型系统相关的见解，并且应该很容易翻译成预防和治疗这些人类常见肝胆疾病的方法。

DESCRIPTION (provided by applicant): The objectives of this application are to use biophysical and pathophysiologic rationale and physical, chemical, biochemical and molecular biologic techniques to advance fundamental understanding of bile and its two major dysfunctions, namely cholestasis and gallstones of both pigment and cholesterol types, i) The first aim will determine whether enterohepatic infection with Helicobacter rodentium and hepaticus, both common human and murine enterobiliary pathogens, is the final common trigger in cholesterol gallstone pathogenesis via nucleation of cholesterol supersaturated bile. Studies will be carried out on genetically gallstone-susceptible mice coupled with in vitro analysis of cholesterol nucleation from model and native biles as well as quantifying evidence of Helicobacter infection in human biliary tissues, ii) Aim two will quantify the activity of the pathway responsible for trimethylation of phosphatidylethanolamine to phosphatidylcholine on the canalicular membrane in the lithogenic state, which may be coupled with biliary cholesterol hypersecretion. Elevation of plasma and bile homocysteine, a by-product of this reaction, may serve as a lithogenic marker and shed light on vicinal and distal organ dysfunction, iii) The third aim will investigate, and unambiguously prove, enterohepatic cycling of bilirubin and 'black' pigment gallstones in the setting of severe bile salt malabsorption in the Slc10a2 null mouse and determine its prevention by nonabsorbed hydrogels containing covalently linked cholic acid, a strong bilirubin binder, or beta-glucaro,1-4 lactone, a potent inhibitor of bacterial beta-glucuronidase. iv) Aim four will work out, both experimentally and by molecular dynamic simulations, the physical states of conjugated and unconjugated bilirubins in native biles and define the thermodynamic conditions required for "black" pigment gallstone formation in human biles, v) The fifth aim will explore cholestasis and pigment "sludge" and gallstone formation associated with total parenteral nutrition, focusing on the lack of CCK and secretin from enteral starvation. The hormonal deficits cause enterohepatic cycling of unconjugated bilirubin which engenders hyperbilirubinbilia and also results in less alkaline hepatic bile, where endogenous beta-glucuronidase hydrolysis of bilirubin glucuronides and calcium bilirubinate precipitation occurs. The results of these hypothesis-driven basic research aims will provide insights that correlate native and model systems and should be readily translatable to prevent and treat these common hepatobiliarv diseases in humans.