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

项目摘要/摘要 这项K08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无党派人士的目标前进 内科科学家，研究阻塞性睡眠呼吸暂停(OSA)的代谢后果；以及b) 确定阻塞性睡眠呼吸暂停综合征间歇性低氧(IH)对非酒精性疾病的发生和发展的影响 脂肪肝(NAFLD)。梅萨维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 培训计划将为梅萨维博士提供代谢病理生物学方面的新知识和研究技能 阻塞性睡眠呼吸暂停综合征的功能障碍。这将通过加州大学丰富的实验室经验和课程工作来实现 圣地亚哥，这将为梅萨维博士提供实验设计、实验室程序方面的额外专业知识， 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，其特点是反复发作 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，在这种情况下，肝脏脂肪变性和 糖代谢失调可能最终导致肝硬变、需要移植和肝脏相关死亡。 阻塞性睡眠呼吸暂停综合征与非酒精性脂肪性肝病之间的联系机制尚不清楚。之前的动物研究已经证明 IH加剧了饮食诱导肥胖小鼠的肝脏脂肪变性和纤维化，这与人类的研究结果相同 研究对象。实验性NAFLD中的肝脏脂肪变性降低了肝脏的氧分压； 叠加IH。肝脏脂肪变性还会增加缺氧诱导因子-1(HIF-1)，这是一种细胞调节因子 对缺氧的反应。我们已经证明，肝细胞缺氧诱导因子-1介导了几种关键酶的表达 在实验性NAFLD中，肝脏中脂肪酸代谢的变化，以及肝纤维化的进展。因此，我们 假设阻塞性睡眠呼吸暂停综合征中的IH可能通过HIF-1的激活及其下游而恶化NAFLD的表型 效果。我们将在三个具体目标上检验这一假说：1)确定HIF-1作为IH-1的介质的作用。 诱导肝脂肪变性和糖代谢紊乱；2)确定HIF-1在IH-1中的作用。 实验性NAFLD致小鼠肝纤维化及反义寡核苷酸的影响 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 在其他类型的肝细胞中。我们可以使用的工具包括特定细胞类型的HIF-1α基因敲除，这将有助于 本地化HIF-1效果。这一建议的主要方法包括在啮齿类动物中联合建模OSA和NAFLD， 反义敲除肝脏缺氧诱导因子-1α、干扰和全基因组鸟枪法测序 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R01提交奠定了基础，并将使我们能够回答一个根本上重要的问题 关于低氧和HIF-1在阻塞性睡眠呼吸暂停综合征和非酒精性脂肪肝患者中的作用，并可能与 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.