Targeting hepatic mitochondrial function in humans with NAFLD using insulin sensitizers

项目摘要/摘要 非酒精性脂肪性肝病(NAFLD)描述了相对良性的一系列肝脏异常 非酒精性脂肪肝(NAFL)中多余脂肪的储存到更不祥的非酒精性脂肪性肝炎(NASH)， 以肝细胞损伤、坏死性炎症和纤维化为特征。NASH的肝脏损伤最快 肝细胞癌的不断增长的原因，现在是最常见的原因肝移植 女人。NAFLD的患病率与肥胖、胰岛素抵抗和2型糖尿病(T2D)的患病率相似，以及 患有这些合并症的患者发生危及生命的肝脏结果的风险更大。然而，没有 批准了NAFLD的治疗方法，迫切需要新的策略来抑制这种新的表观感染。 德米奇。我们的目标是在人类学科中使用创新和高度集成的方法来获得机械性 对NAFLD发病机制的洞察将促进新疗法的发展，以解决 潜在的病理过程。在NAFL病程的早期，肝脏脂质输送增加是一个结论。 高脂饮食、脂肪组织胰岛素抵抗和脂质摄取和从头合成增加的频率。 这种代谢环境增加了NAFL肝脏的线粒体密度、氧化能力和TCA循环通量， 最终可能会压倒抗氧化防御机制，促进NASH的发展。在……里面 临床前研究我们观察到胰岛素增敏剂和PPARγ激动剂吡格列酮直接抑制 这些NAFL肝脏中的肝脏线粒体氧化能力和TCA循环活性增加。因此，在 遵循三个具体目标，我们将利用稳定同位素示踪方法来检验中心假设 肝线粒体功能是人类NAFLD的靶向特征。在具体目标1中，我们将首先量化- 使用三稳定同位素示踪法([U-])测量肝线粒体跨NAFLD谱的通量 13C]丙酸、[3，4-13C2]葡萄糖和2H2O)与2H和13C核磁共振分析相结合，以同时询问 特征良好的NAFL和NASH患者的肝脏葡萄糖代谢和线粒体通量。下一首, 在特定目标2中，我们将评估作为胰岛素增敏剂靶点的人类肝脏线粒体功能和 将询问外周PPARy激活对肝脏线粒体通量和葡萄糖代谢的贡献。 非酒精性脂肪肝的代谢。最后，在特定的目标3中，我们将确定控制 单核基因组学结合鸟枪法研究吡格列酮对非酒精性脂肪肝小鼠的影响 脂质组学方法检测实质细胞和非实质细胞转录并定量检测 慢性吡格列酮治疗后肝活检中的线粒体脂质重塑。 总的来说，这些研究将确定未来可以利用的机制，以促进设计 安全针对T2D和NAFLD的新疗法。

PROJECT SUMMARY/ABSTRACT Nonalcoholic fatty liver disease (NAFLD) describes a spectrum of liver abnormalities from the relatively benign storage of excess fat in nonalcoholic fatty liver (NAFL) to the more ominous nonalcoholic steatohepatitis (NASH), characterized by hepatocellular injury, necroinflammation, and fibrosis. Liver damage in NASH is the fastest growing cause of hepatocellular carcinoma and is now the most common reason for liver transplantation in women. The prevalence of NAFLD parallels that of obesity, insulin resistance and type 2 diabetes (T2D), and patients with these comorbidities are at greater risk of life-threatening liver outcomes. However, there are no approved treatments for NAFLD and there is an urgent need for new strategies to suppress this emerging epi- demic. Our goal is to employ innovative and highly integrative approaches in human subjects to gain mechanistic insight into the pathogenesis of NAFLD that will foster the development of new therapeutics that address the underlying pathological processes. Early in the course of NAFL, hepatic lipid delivery is increased as a conse- quence of high fat diets, adipose tissue insulin resistance and increased uptake and de novo synthesis of lipids. This metabolic milieu increases mitochondrial density, oxidative capacity and TCA cycle flux in NAFL livers, which eventually may overwhelm antioxidant defense mechanisms to promote the development of NASH. In preclinical studies we observed that the insulin sensitizer and PPARγ agonist pioglitazone directly suppressed elevated hepatic mitochondrial oxidative capacity and TCA cycle activity in these NAFL livers. Therefore, in the following three specific aims we will utilize stable isotope tracer methodology to test the central hypothesis that hepatic mitochondrial function is a targetable feature of NAFLD in humans. In Specific Aim 1 we will first quanti- tate hepatic mitochondrial fluxes across the NAFLD spectrum using a triple stable isotope tracer approach ([U- 13C]propionate, [3,4-13C2]glucose and 2H2O) coupled to 2H and 13C NMR analysis to simultaneously interrogate hepatic glucose metabolism and mitochondrial fluxes in well characterized patients with NAFL and NASH. Next, in Specific Aim 2 we will evaluate hepatic mitochondrial function as a target of insulin sensitizers in humans and will interrogate the contribution of peripheral PPARy agonism on hepatic mitochondrial fluxes and glucose me- tabolism in NAFLD. Finally, in Specific Aim 3 we will determine the mitochondrial mechanisms governing the effect of pioglitazone on NAFLD: In mice with NAFLD using a combination of single-nuclei genomics and shotgun lipidomics approaches to examine parenchymal and non-parenchymal cell transcriptomics and to quantitate mi- tochondrial lipid remodeling, respectively, in liver biopsies obtained following chronic pioglitazone treatment. Collectively, these studies will identify mechanisms that can be exploited in the future to foster the design of novel therapies that safely target T2D and NAFLD.