Hypoxia, HIF-1, and the progression of nonalcoholic fatty liver disease in obstructive sleep apnea

项目总结/摘要 本K 08提案的目标是：a）促进关键科学和专业技能的发展 这将使候选人奥马尔·梅萨维博士朝着成为独立候选人的目标前进。 医师-科学家，检查阻塞性睡眠呼吸暂停（OSA）的代谢后果;和B） 确定OSA中间歇性缺氧（IH）如何影响非酒精性 脂肪肝（NAFLD）。Mesarwi博士和他在加州大学圣地亚哥分校的导师们设计了一个全面的 培训计划，这将使Mesarwi博士在代谢性疾病的病理生物学方面获得新的知识和研究技能。 OSA中的功能障碍。这将通过丰富的实验室经验和课程在加州大学完成 圣地亚哥，这将提供梅萨维博士在实验设计，实验室程序， 数据分析和科学交流。阻塞性睡眠呼吸暂停是一种常见的疾病， 睡眠时上呼吸道狭窄，导致慢性IH。OSA与更严重的NAFLD相关 表型，由IH驱动。NAFLD是一种非常普遍的疾病，其中肝脂肪变性和 葡萄糖代谢失调可能最终导致肝硬化、需要移植和肝脏相关死亡。 联系OSA和NAFLD的机制相对未知。之前的动物实验已经证明 IH加剧了饮食诱导肥胖小鼠的肝脂肪变性和纤维化，这与人类的研究结果相似。 科目实验性NAFLD中的肝脂肪变性降低了肝氧张力; 叠加IH。肝脂肪变性还增加了缺氧诱导因子-1（HIF-1），一种细胞凋亡的调节因子。 对缺氧的反应我们已经发现肝细胞HIF-1介导了几种关键酶的表达， 肝脏脂肪酸代谢，以及实验性NAFLD中肝纤维化的进展。所以我们 假设OSA中IH可能通过HIF-1激活及其下游信号通路恶化NAFLD表型， 方面的影响.我们将在三个具体目标中检验这一假设：1）确定HIF-1作为IH-1介导者的作用， 诱导的肝脏脂肪变性和肝脏葡萄糖代谢失调; 2）确定HIF-1在IH-2中的作用。 诱导实验性NAFLD小鼠肝纤维化，以及反义寡核苷酸的作用 靶向HIF-1α逆转肝纤维化; 3）确定HIF-1和IH在介导肝纤维化中的作用 在其他肝细胞类型。我们可用的工具包括细胞类型特异性HIF-1α敲除，这将有助于 局部化HIF-1效应。该提案的主要方法包括在啮齿动物中共同建模OSA和NAFLD， 肝HIF-1α的反义敲低、RNA干扰和全基因组鸟枪测序（RNA- Seq）。这些具体目标的成功实施将为博士提供严格的培训计划。 Mesarwi，为R 01提交奠定基础，并将使我们能够回答一个根本性的重要问题， 关于缺氧和HIF-1在OSA和NAFLD患者中的作用的问题， HIF-1和/或其下游介质作为预防OSA代谢紊乱的治疗靶点。

PROJECT SUMMARY/ABSTRACT The objectives of this K08 proposal are: a) To foster the development of critical scientific and professional skills which will allow the candidate, Dr. Omar Mesarwi, to progress toward his goal of becoming an independent physician-scientist, examining the metabolic consequences of obstructive sleep apnea (OSA); and b) To determine how intermittent hypoxia (IH) in OSA may impact the development and progression of nonalcoholic fatty liver disease (NAFLD). Dr. Mesarwi and his mentors at UC San Diego have designed a comprehensive training plan that will afford Dr. Mesarwi new knowledge and research skills in the pathobiology of metabolic dysfunction in OSA. This will be accomplished through extensive laboratory experience and coursework at UC San Diego, which will provide Dr. Mesarwi additional expertise in experimental design, laboratory procedures, data analysis, and scientific communication. OSA is a common condition which is characterized by recurrent upper airway narrowing during sleep, leading to chronic IH. OSA is associated with a more severe NAFLD phenotype, driven by IH. NAFLD is an extremely prevalent condition in which hepatic steatosis and dysregulated glucose metabolism may ultimately lead to cirrhosis, need for transplant, and liver-related death. The mechanisms which link OSA and NAFLD are relatively unknown. Previous animal work has demonstrated that IH exacerbates hepatic steatosis and fibrosis in mice with diet-induced obesity, mirroring findings in human subjects. Hepatic steatosis in experimental NAFLD reduces liver oxygen tension; it is further reduced with superimposed IH. Hepatic steatosis also increases hypoxia inducible factor-1 (HIF-1), a regulator of the cellular response to hypoxia. We have shown that hepatocyte HIF-1 mediates the expression of several key enzymes of fatty acid metabolism in the liver, and the progression of liver fibrosis in experimental NAFLD. Therefore, we hypothesize that IH in OSA may worsen the NAFLD phenotype through HIF-1 activation and its downstream effects. We will test this hypothesis in three Specific Aims: 1) Determine the role of HIF-1 as a mediator of IH- induced hepatic steatosis and dysregulated hepatic glucose metabolism; 2) Determine the role of HIF-1 on IH- induced hepatic fibrosis in mice with experimental NAFLD, and the effect of antisense oligonucleotides targeting HIF-1α in reversing liver fibrosis; and 3) Determine the role of HIF-1 and IH in mediating liver fibrosis in other hepatic cell types. Tools available to us include cell type-specific HIF-1α knockout, which will help localize HIF-1 effects. Major methods for this proposal include co-modeling OSA and NAFLD in rodents, antisense knockdown of hepatic HIF-1α, RNA interference, and whole genome shotgun sequencing (RNA- Seq). Successful implementation of these Specific Aims will provide a rigorous training program for Dr. Mesarwi, laying the groundwork for R01 submission, and will allow us to answer a fundamentally important question about the role of hypoxia and HIF-1 in patients with OSA and NAFLD, and possibly to credential HIF-1 and/or its downstream mediators as therapeutic targets in preventing metabolic derangement in OSA.