Mechanisms of Vascular Dysfunction in Cirrhosis

描述(由申请人提供)： 这是一项为期5年的培训计划，培训对象是胃肠病和肝脏病学方面的内科导师科学家。首席研究员是马里兰大学医学院(UMSOM)胃肠病和肝病学部的初级教员。Thomas Pallone博士和Jean-Pierre Raufman博士将共同指导PI的科学培训。Pallone博士(医学和生理学系教授)是微循环领域的著名领导者。Raufman博士(胃肠病和肝病科主任)在胆汁酸信号转导方面拥有专业知识。一个由知名科学家/导师组成的咨询委员会将提供科学和职业指导。UMSOM为PI的学术生涯发展提供了理想的培训环境。指导、授课、坚定不移的机构支持和承诺相结合，将最大限度地提高PI启动富有成效的科学职业生涯的能力。本研究旨在阐明肝硬变时血管功能障碍的机制。初步数据表明：(1)结合胆汁酸(BA)可引起大鼠主动脉扩张；(2)BA介导的血管扩张是内皮依赖和一氧化氮(NO)介导的；(3)M_3受体抑制和消融可减弱BA和乙酰胆碱介导的血管扩张。我们的中心假设是，胆碱能刺激血管内皮细胞介导了肝硬变患者的血管功能障碍和全身血管扩张。其具体目的是(1)确定M3R依赖的信号在胆汁酸介导的血管扩张中的作用；(2)建立胆汁酸介导的肠系膜小动脉张力变化模拟主动脉血管张力的变化；(3)确定M3R在肝硬变小鼠模型中促进血管功能障碍的机制。门脉高压是晚期肝病发病率和死亡率的主要原因，而血管功能障碍在这种情况下对门脉高压的进展有重要作用。所提出的体外和体内互补方法将有助于(A)确定胆碱能刺激在NO介导的EC应激发展中的重要性，(B)阐明BA介导的血管扩张的分子机制，以及(C)在实验性肝硬化动物模型中确定M3R基因敲除对血管功能障碍的影响。这一系列研究将填补在了解肝硬变血管功能障碍机制方面的关键空白，并确定治疗靶向的分子。

DESCRIPTION (provided by applicant): This is a 5-year training plan for a mentored physician scientist in Gastroenterology and Hepatology. The Principal Investigator is a junior faculty member in the Division of Gastroenterology and Hepatology at University of Maryland School of Medicine (UMSOM). Drs. Thomas Pallone and Jean-Pierre Raufman will co-mentor the Pi's scientific training. Dr. Pallone (Professor, Departments of Medicine and Physiology) is a renowned leader in microcirculation. Dr. Raufman (Chief, Division of Gastroenterology and Hepatology) has expertise in bile acid signaling. An Advisory Committee of established scientists/mentors will provide scientific and career guidance. The UMSOM provides an ideal training environment for the Pi's academic career development. The combination of mentoring, didactic coursework, unwavering institutional support and commitment will maximize the Pi's ability to launch a productive scientific career. The proposed study focuses on elucidating the mechanisms of vascular dysfunction in cirrhosis. The preliminary data indicates that (i) conjugated bile acids (BA) induce vasodilation in rodent aortae; (ii) BA-mediated vasodilation is endothelium-dependent and nitric oxide (NO)-mediated; (iii) M3 muscarinic receptor inhibition and ablation attenuates BA- and acetylcholine-mediated vasodilation. Our central hypothesis is that cholinergic stimulation of vascular endothelial cells mediates vascular dysfunction and systemic vasodilation in cirrhosis. The Specific Aims are (1) To define the role of M3R-dependent signaling in bile acid-mediated vasodilation; (2) To establish that bile acid-mediated changes in small mesenteric arterial tone mimic changes in aortic vascular tone; (3) To determine the mechanism whereby M3R contributes to vascular dysfunction in a mouse model of cirrhosis. Portal hypertension is a major cause of morbidity and mortality in advanced liver disease and vascular dysfunction contributes significantly to the progression of portal hypertension in this setting. The proposed complementary in vitro and in vivo approaches will help (a) determine the importance of cholinergic stimulation in the development of NO-mediated stress in EC, (b) elucidate molecular mechanisms of BA- mediated vasodilation and (c) determine the impact of M3R knockdown on vascular dysfunction in the animal model of experimental cirrhosis. This line of investigation will fill critical gaps in understanding the mechanisms of vascular dysfunction in cirrhosis and identify molecules for therapeutic targeting.