Molecular Pathogenesis of Cystic Fibrosis Liver Disease

描述（由申请方提供）：囊性纤维化（CF）（导致多小叶肝硬化的局灶性胆汁纤维化）患者的肝病频率高达43%，患病率随年龄增加而增加。临床上表现为门脉高压的多小叶肝硬化已成为CF发病和过早死亡的第三大原因，当肺部疾病通过或不通过肺移植得到控制时，肝脏疾病是死亡的主要原因。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疗效证据。从这个实验室扩展初步研究，？将研究CF和野生型（WT）小鼠的F508和G551 D鼠模型：1）利用生物物理学、病理生理学和物理化学方法探索pH、胆红蛋白、电解质和胆汁脂质的肝胆分泌异常; 2）确定肠高胆红素血症的发病机制并将其与回肠pH异常、胆盐吸收不良、肝胆汁pH和肝脏疾病相关联; 3）阐明胆盐吸收不良作为诱导的非结合胆红素（UCB）的肠肝循环的原因的病理生理学，重点是回肠胆盐转运体及其对较低碱性内腔pH的响应;此外，研究经hCFTR治疗的CF小鼠以验证肠缺陷的分子性质; 4）对年龄和性别相关的肝脏组织学和超微结构研究进行成像和量化，以使用透射和扫描电子显微镜结合原子发射光谱法检测管内和胆管上皮细胞中的金属铌酸盐沉积，并量化UCB诱导的导管周围炎症、纤维化和闭塞性胆管炎的病理生物学; 5）通过以下方法预防和治疗CF小鼠的慢性肝病：a）用norUDCA靶向胆道系统以增加肝胆汁的pH值，B）通过共价连接的D-葡糖-1，4-内酯或胆酸的非吸收聚合物靶向UCB在远端肠道中的形成和吸收，和c）使用盐酸考来维仑靶向胆盐吸收不良以防止UCB溶解，或通过使用阿米洛利（一种碳酸酐酶激动剂）使内腔pH正常化，或通过用布地奈德上调ASBT活性。从这些假设驱动的具体目标的分子见解应该提供数据，分子理解和药物，可转化为人类与CF，并导致新的模式，预防和治疗CF肝病。

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.