Alimentary Tract Lipids in Health and Disease

描述（申请人提供）：本申请的目的是使用生物物理学和病理生理学原理以及物理、化学、生物化学和分子生物学技术来促进对胆汁及其两种主要功能障碍的基本理解，即胆汁淤积和色素和胆固醇类型的胆结石。i）第一个目的将确定是否存在啮齿螺杆菌和肝螺杆菌的肠肝感染，两者都是常见的人和鼠的肠胆病原体，是通过胆固醇过饱和胆汁成核的胆固醇结石发病机制中的最终常见触发因素。研究将在遗传上胆结石易感的小鼠上进行，结合来自模型和天然胆汁的胆固醇成核的体外分析以及人胆管组织中螺杆菌感染的定量证据。ii）目的二将定量在致石状态下负责小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分泌过多有关。血浆和胆汁同型半胱氨酸的升高，这种反应的副产物，可以作为一个致石标志物，并揭示了邻近和远端器官功能障碍，iii）第三个目标将调查，并明确证明，在Slc 10a 2基因敲除小鼠中严重胆盐吸收不良的情况下胆红素和“黑色”色素胆结石的肝肠循环，并确定通过含有共价键的非吸收水凝胶的预防连接的胆酸，强胆红素结合剂，或β-glucaro，1-4内酯，细菌β-葡萄糖醛酸酶的有效抑制剂。iv）第四个目标将通过实验和分子动力学模拟来确定天然胆汁中缀合和未缀合胆红蛋白的物理状态，并定义人胆汁中“黑色”色素胆结石形成所需的热力学条件。v）第五个目标将探索胆汁淤积和色素“淤渣”以及与全胃肠外营养相关的胆结石形成，重点关注肠饥饿引起的CCK和促胰液素缺乏。激素缺乏导致未结合胆红素的肝肠循环，这会导致高胆红素血症，也会导致碱性肝胆汁减少，其中发生胆红素葡萄糖醛酸苷的内源性β-葡萄糖醛酸酶水解和胆红素钙沉淀。这些假设驱动的基础研究目标的结果将提供与天然系统和模型系统相关的见解，并且应该易于翻译以预防和治疗人类这些常见的肝胆疾病。

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.