Molecular Pathogenesis of Cystic Fibrosis Liver Disease

描述（由申请人提供）：囊性纤维化（CF）（局灶性胆道纤维化导致多小叶肝硬化）患者肝脏疾病的发生率高达43%，患病率随着年龄的增长而增加。临床上以门静脉高压症为表现的多小叶性肝硬化已成为CF发病和过早死亡的第三大原因，而当肺部疾病通过肺移植或不进行肺移植得到控制时，肝脏疾病是导致CF死亡的主要原因。CF肝病的病因、机制和发病机制尚不清楚，目前熊去氧胆酸的处方没有令人信服的证据证明其疗效。扩展这个实验室的初步研究，？研究CF和野生型小鼠F508和G551D小鼠模型：1)利用生物物理、病理生理和物理化学方法探讨肝胆分泌pH、胆红素、电解质和胆脂的异常；2)确定肠性高胆红素胆结石的发病机制，并将其与回肠pH异常、胆盐吸收不良、肝胆汁pH和肝脏疾病联系起来；3)阐明胆盐吸收不良作为诱导非共轭胆红素（UCB）肠肝循环的病理生理机制，重点研究回肠胆盐转运体及其对低碱性管腔pH的反应；此外，对肠道hcftr拯救的CF小鼠进行研究，验证肠道缺陷的分子性质；4)对年龄和性别相关的肝脏组织和超微结构进行成像和量化研究，利用透射电镜和扫描电镜结合原子发射光谱检测金属胆红素在导管内和胆道上皮细胞中的沉积，量化ucb诱导的导管周炎症、纤维生成和梗阻性胆管炎的病理生物学；5)预防和治疗CF小鼠的慢性肝病：a)用norUDCA靶向胆道树，增加肝胆汁的pH值；b)用带有共价连接的d -葡罗-1,4-内酯或胆酸的非吸收聚合物，靶向UCB在远端肠道的形成和吸收；c)用colesevelam HCI靶向胆汁盐吸收不良，阻止UCB的溶解度或用碳酸酐酶受体拮抗剂amiloride使腔内pH值正常。或通过布地奈德上调ASBT活性。从这些假设驱动的特定目标中获得的分子见解应该为CF患者提供可翻译的数据、分子理解和药物，并导致CF肝病预防和治疗的新模式。

DESCRIPTION (provided by applicant): The frequency of liver disease in humans with cystic fibrosis (CF) (focal biliary fibrosis leading to multilobular cirrhosis) ranges up to 43%, with prevalence increasing with age. Multilobular cirrhosis manifesting clinically with portal hypertension has become the third leading cause of morbidity and premature death in CF, and when pulmonary disease is controlled with or without lung transplantation, liver disease is the leading cause of death. The etiology, mechanisms and pathogenesis of CF liver disease are unknown, and currently ursodeoxycholic acid is prescribed without compelling evidence of its efficacy. Extending preliminary studies from this laboratory, the ?F508 and G551D murine models of CF and wild-type (WT) mice will be studied: 1) to explore the hepatobiliary secretory abnormalities of pH, bilirubins, electrolytes and biliary lipids utilizing biophysical, pathophysiological and physical-chemical approaches; 2) to determine the pathogenesis of enteric hyperbilirubinbilia and to correlate this with ileal pH abnormalities, bile salt malabsorption, hepatic bile pH and liver disease; 3) to elucidate the pathophysiology of bile salt malabsorption as a cause of induced enterohepatic cycling of unconjugated bilirubin (UCB), focusing on the ileal bile salt transporter and its response to less alkaline lumenal pH; in addition, to study intestinally hCFTR-rescued CF mice to verify the molecular nature of the intestinal defect; 4) to image and quantify age and gender-related liver histology and ultrastructural studies to detect deposits of metal bilirubinates intraductally and in biliary epithelial cells using transmission and scanning electron microscopy coupled with atomic emission spectroscopy, and to quantify the pathobiology of UCB-induced periductal inflammation, fibrogenesis and obliterative cholangitis; 5) to prevent and treat chronic liver disease of CF mice by a) targeting the biliary tree with norUDCA to increase pH of hepatic bile, b) targeting UCB formation and absorption in the distal gut by non-absorbed polymers with covalently linked D-glucaro-1,4-lactone or cholic acid, and c) targeting bile salt malabsorption using colesevelam HCI to prevent solubility of UCB or by normalizing the lumenal pH using amiloride, a carbonic anhydrase agonist, or by upregulating ASBT activity with budesonide. The molecular insights from these hypothesis-driven specific aims should provide data, molecular understanding and agents that are translatable to humans with CF and lead to new modalities for prevention and treatment of CF liver disease.