Pathogenesis of the Metabolic Syndrome

代谢综合征的发病机制

• 批准号: 8586874
• 负责人: W Timothy GARVEY
• 金额: --
• 依托单位: BIRMINGHAM VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8586874
• 关键词: 1,2-diacylglycerol; 2,4-thiazolidinedione; Abdomen; Activity Cycles; Address; Adipose tissue; Affect; African American; Amino Acids; Biological Markers; Biopsy; Blood Circulation; Body Composition; Body Weight decreased; Carbohydrates; Carboxylic Acids; Cardiovascular Diseases; Ceramides; Complex; DEXA; Data; Defect; Development; Diet; Diglycerides; Disease; Energy Metabolism; Euglycemic Clamping; European; Fatty Acids; Generations; Glucose; Glucose Clamp; Goals; Grant; Health Care Costs; Heart Diseases; Hormones; Hour; Human; Human Volunteers; Hydroxyl Radical; Hyperinsulinism; Indirect Calorimetry; Individual; Inflammatory; Insulin; Insulin Receptor; Insulin Resistance; Link; Lipid Peroxidation; Lipid Peroxides; Lipids; Measures; Mediating; Medicine; Metabolic; Metabolic syndrome; Metabolism; Mitochondria; Molecular; Muscle; NADH dehydrogenase (ubiquinone); NF-kappa B; NMR Spectroscopy; Non-Insulin-Dependent Diabetes Mellitus; Nutrient; Oxidative Stress; Pathogenesis; Pathway interactions; Patients; Pattern; Phosphorylation; Physiological; Pioglitazone; Plasma; Population; Prediabetes syndrome; Process; Protein-Serine-Threonine Kinases; Proteins; Reactive Oxygen Species; Research; Research Design; Resolution; Respiration; Rest; Rodent; Role; Serine; Signal Transduction; Skeletal Muscle; Stress; Technology; Testing; Thiazolidinediones; Tissues; Translational Research; Triglycerides; Urine; Veterans; acylcarnitine; adiponectin; base; cytokine; desensitization; diabetic; glucose metabolism; improved; insulin sensitivity; insulin signaling; intervention effect; lipid metabolism; long chain fatty acid; metabolomics; non-diabetic; novel; novel diagnostics; organic acid; oxidation; prevent; public health relevance; respiratory; response; theories; weight maintenance

DESCRIPTION (provided by applicant): The spectrum of cardiometabolic disease encompasses the Metabolic Syndrome, Pre-diabetes, Type 2 Diabetes (T2DM), and cardiovascular disease, and these diseases are responsible for a huge burden of patient suffering and health care costs among veterans and the US population in general. Insulin resistance at the level of skeletal muscle is central to the underlying pathogenesis of all these disease manifestations. Regarding the mechanism of insulin resistance, the conventional hypothesis is that oxidation of long-chain fatty acids (LCFA) is impaired while availability is increased, and this results in the accumulation of intramyocellular lipid (IMCL) and metabolites of LCFAs such as diacylglycerol, LCFA-CoAs, and ceramides. These latter compounds activate various serine kinases, such as PKC or IKK2 (in association with activation of NF-:B), which then phosphorylate insulin receptor substrate (IRS) molecules resulting in impaired insulin signal transduction. However, our preliminary data point to an alternative or complementary pathophysiological process. The first clue was that IMCL was completely independent of insulin sensitivity in African Americans, while oxidative stress related to lipid peroxidation in muscle was predictive of insulin resistance in both European- and African-Americans. The second clue was provided by metabolomic studies of plasma obtained from normal controls and insulin-resistant patients with T2DM. The metabolomic profile in T2DM was consistent with incomplete oxidation of long-chain fatty acids (LCFA) as evidenced by accumulation of medium chain acylcarnitines, rather than increased LCFAs and accumulation as IMCL triglyceride, together with decreased tri-carboxylic acid (TCA) cycle activity and diminished anaplerosis. Given these observations, we wish to test a novel hypothesis that the abnormal metabolome is the result of intrinsic mitochondrial defects that both impair FA oxidation and generate reactive oxygen species (ROS). Activation of serine kinases is then mediated either directly by medium-chain acylcarnitines and/or by peroxidized lipids generated by mitochondrial ROS that activate inflammatory pathways (e.g., NG-:B). In this proposal, we will test these hypotheses in humans. Normoglycemic insulin sensitive and insulin resistant subjects, and patients with T2DM will be metabolically characterized by hyperinsulinemic clamps, body composition, IMCL, energy expenditure and substrate oxidation rates, and will be studied before and after perturbations that alter insulin sensitivity including short-term very low calorie diet, after stabilization following 10% weight loss, and insulin-sensitizing thiazolidinedione treatment. Metabolomic profiles will be assessed for acylcarnitines, fatty acids, organic acids, amino acids, and LCFA-CoAs in plasma, urine, and in biopsied muscle tissue. In addition, mitochondria isolated from muscle will be functionally studied for substrate oxidation capacity using high resolution respirometry, reactive oxygen species generation, and activity of individual respiratory complexes. Oxidative stress will be measured in muscle by hydroxyl-nonenal and protein carbonyls. The effect of oxidative stress and/or metabolomic analytes to activate inflammatory pathways in muscle leading to serine phosphorylation and desensitization of IRS and insulin signaling will be examined. These studies represent a state-of-the-art application of new metabolomics technologies, combined with molecular studies of mitochondrial function and insulin signaling, in human muscle, and will test new hypotheses regarding the link between abnormal lipid metabolism and insulin resistance. These data will predictably identify new diagnostic biomarkers for insulin resistance and T2DM, and advance our understanding of molecular mechanisms underlying human insulin resistance. PUBLIC HEALTH RELEVANCE: Most patients with Type 2 Diabetes, Pre-Diabetes, Metabolic Syndrome, and heart disease are insulin resistant due to an inability of insulin to move glucose from bloodstream into skeletal muscle. These interrelated diseases cause a huge burden of suffering and health care costs. Improved ways to treat and prevent these diseases will require a better understanding of the molecular causes of insulin resistance. Therefore, based on preliminary data, will test a new theory for how abnormal fat metabolism leads to abnormal glucose metabolism. Our studies will involve human patients before and after diet-induced weight loss and a medicine that makes muscle more insulin sensitive. These studies represent a state-of-the-art application of new metabolomics technologies, combined with molecular studies of mitochondrial function and insulin action, in human muscle. These data will predictably identify new diagnostic biomarkers for insulin resistance and T2DM, and advance our understanding of molecular mechanisms underlying human insulin resistance.

描述（由申请人提供）： 心脏代谢疾病包括代谢综合征、糖尿病前期、2 型糖尿病 (T2DM) 和心血管疾病，这些疾病给退伍军人和美国民众带来巨大的患者痛苦和医疗费用负担。骨骼肌水平的胰岛素抵抗是所有这些疾病表现的潜在发病机制的核心。关于胰岛素抵抗的机制，传统的假设是长链脂肪酸（LCFA）的氧化受损而可用性增加，导致肌细胞内脂质（IMCL）和LCFA的代谢物（如二酰基甘油、LCFA）的积累-辅酶A和神经酰胺。后面这些化合物会激活各种丝氨酸激酶，例如 PKC 或 IKK2（与 NF-:B 的激活相关），然后磷酸化胰岛素受体底物 (IRS) 分子，导致胰岛素信号转导受损。然而，我们的初步数据表明存在替代或补充的病理生理过程。第一条线索是，IMCL 完全独立于非裔美国人的胰岛素敏感性，而与肌肉中脂质过氧化相关的氧化应激可预测欧洲和非裔美国人的胰岛素抵抗。第二条线索是通过对正常对照和胰岛素抵抗 T2DM 患者血浆进行的代谢组学研究提供的。 T2DM 的代谢组学特征与长链脂肪酸 (LCFA) 的不完全氧化一致，如中链酰基肉碱的积累所证明，而不是 LCFA 增加和 IMCL 甘油三酯积累，以及三羧酸 (TCA) 循环活性降低并减少回补。 鉴于这些观察结果，我们希望检验一个新的假设，即异常代谢组是内在线粒体缺陷的结果，这种缺陷既损害 FA 氧化又产生活性氧 (ROS)。然后，丝氨酸激酶的激活由中链酰基肉碱和/或由激活炎症途径的线粒体 ROS 产生的过氧化脂质直接介导（例如 NG-:B）。在本提案中，我们将在人类身上测试这些假设。血糖正常的胰岛素敏感性和胰岛素抵抗受试者以及 T2DM 患者的代谢特征将包括高胰岛素钳夹、身体成分、IMCL、能量消耗和底物氧化率，并将在改变胰岛素敏感性的扰动（包括短期极低）之前和之后进行研究热量饮食，体重减轻 10% 稳定后，以及胰岛素增敏噻唑烷二酮治疗。将评估血浆、尿液和活检肌肉组织中酰基肉碱、脂肪酸、有机酸、氨基酸和 LCFA-CoAs 的代谢组学特征。此外，将从肌肉中分离的线粒体使用高分辨率呼​​吸测定法、活性氧生成和单个呼吸复合物的活性来进行功能研究，以了解底物氧化能力。将通过羟基壬烯醛和蛋白质羰基来测量肌肉中的氧化应激。将检查氧化应激和/或代谢组分析物激活肌肉炎症途径导致丝氨酸磷酸化以及 IRS 和胰岛素信号转导脱敏的影响。 这些研究代表了新代谢组学技术的最先进应用，结合线粒体功能和胰岛素信号传导的分子研究，在人体肌肉中，并将测试有关异常脂质代谢与胰岛素抵抗之间联系的新假设。这些数据将有望确定胰岛素抵抗和 T2DM 的新诊断生物标志物，并增进我们对人类胰岛素抵抗分子机制的理解。 公共卫生相关性： 大多数患有 2 型糖尿病、糖尿病前期、代谢综合征和心脏病的患者都存在胰岛素抵抗，因为胰岛素无法将葡萄糖从血液转移到骨骼肌中。这些相互关联的疾病造成巨大的痛苦负担和医疗费用。改进治疗和预防这些疾病的方法需要更好地了解胰岛素抵抗的分子原因。因此，基于初步数据，将检验脂肪代谢异常如何导致糖代谢异常的新理论。我们的研究将涉及饮食诱导减肥前后的人类患者以及使肌肉对胰岛素更加敏感的药物。这些研究代表了新代谢组学技术与线粒体功能和胰岛素作用的分子研究在人体肌肉中的最先进应用。这些数据将有望确定胰岛素抵抗和 T2DM 的新诊断生物标志物，并增进我们对人类胰岛素抵抗分子机制的理解。