Hepatocyte PPARgamma regulated mechanisms in NAFLD and lipid homeostasis

NAFLD 和脂质稳态中肝细胞 PPARgamma 的调节机制

• 批准号: 10319915
• 负责人: Jose Cordoba-Chacon
• 金额: $ 13.65万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-02-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10319915
• 关键词: 2-acylglycerol O-acyltransferase; Address; Adipose tissue; Adult; Affect; Agonist; Alcohol consumption; Benign; Blood; CD36 gene; Cardiovascular Diseases; Cholesterol; Clinical; Development; Diabetes Mellitus; Diet; Diglycerides; Disease Progression; Dyslipidemias; Endocrine; Enterobacteria phage P1 Cre recombinase; Esterification; Fatty Acids; Fatty Liver; Fatty acid glycerol esters; Fibrosis; Functional disorder; Gastroenterology; Gene Expression; Genes; Health system; Hepatic; Hepatocyte; Hepatology; High Fat Diet; Homeostasis; Impairment; Insulin Resistance; Intestines; Lead; Lipase; Lipid Biochemistry; Lipids; Liver; Liver diseases; Mediating; Mentored Research Scientist Development Award; Metabolic; Metabolic Diseases; Metabolic syndrome; Molecular; Monoglycerides; Mus; Muscle; Myocardium; Non obese; Nuclear Receptors; Obesity; Oral; Outcome; PPAR gamma; Pharmacologic Substance; Plasma; Population; Process; Radiolabeled; Reducing diet; Regulation; Resolution; Risk Factors; Role; Solid; Sucrose; Testing; Thiazolidinediones; Time; Tissues; Training; Triglycerides; absorption; adeno-associated viral vector; base; chronic liver disease; design; diabetic; drug development; fatty liver disease; feeding; human model; insulin sensitivity; knock-down; lipid metabolism; liver transplantation; mouse model; non-alcoholic fatty liver; non-alcoholic fatty liver disease; nonalcoholic steatohepatitis; novel; prevent; programs; response; restoration; simple steatosis; therapeutically effective; translocase; uptake

Abstract – Non-alcoholic fatty liver disease (NAFLD) encompasses non-alcoholic fatty liver (NAFL/steatosis) to non-alcoholic steatohepatitis (NASH). Although simple steatosis can be “benign”, it is an independent risk factor for NASH development. Thiazolidinediones (TZD) are PPARγ agonists used to reduce steatosis in diabetics with NASH. However, the impact of TZD on steatosis is limited, without any resolution of fibrosis. The antisteatotic actions of TZD may be due to reduced insulin resistance in both humans and mouse models. However, TZD-mediated activation of hepatocyte PPARγ may offset the putative antisteatogenic effects of TZD and prevent any reduction in fibrosis. This is based on the following observations: 1) Hepatic PPARγ dramatically increases in NAFLD; 2) TZD exacerbate steatosis in a hepatocyte PPARγ-dependent fashion in mice; and 3) Clinically, the antisteatogenic effect of TZD is limited to the reduction in insulin resistance. To date, the impact of hepatocyte PPARγ-regulated lipid metabolism on NAFLD is poorly understood. Therefore we have knocked-down hepatocyte PPARγ (>99.5%) in adult PPARγfl/fl mice using an adeno-associated viral vector that express Cre recombinase only in hepatocytes (AAV8-TBGp-Cre). Loss of hepatocyte PPARγ reduced diet-induced steatosis, therefore in SA#1 studies are proposed to determine how loss of hepatocyte PPARγ prevents diet-induced NAFLD. We hypothesize that the reduction in Cd36-mediated FA uptake and/or Mogat1-mediated FA re-esterification, observed after loss of hepatocyte PPARγ, are critical for the reduction in steatosis and subsequent development of NASH. To test this hypothesis, adult PPARγfl/fl mice will be fed a high fat, high cholesterol, high sucrose diet (HF-HC-HSD) known to induce steatosis (8 weeks of diet) and NASH (27 weeks of diet). Hepatocyte PPARγ will be knocked down, without or with restoration of Cd36 (FA translocase) or Mogat1 (Monoacylglycerol acyltransferase). Hepatic FA uptake, MOGAT activity, FA composition of triacylglycerols (TAG), diacylglycerols (DAG), and monoacylglycerols (MAG)], gene expression and liver and systemic metabolic pathophysiology will be assessed. Although loss of hepatocyte PPARγ reduced steatosis, it led to postprandial dyslipidemia. Therefore in SA#2 studies are proposed to determine the mechanism(s) that promotes postprandial dyslipidemia after loss of hepatocyte PPARγ. We hypothesize that dyslipidemia associated with specific loss of hepatocyte PPARγ is due to enhanced intestinal fat absorption which will be tested by feeding mice a diet containing a nonabsorbable fat or after oral delivery of radio-labeled TAG in the presence of tyloxapol. We also hypothesize that changes in tissue-specific TAG uptake is impaired after loss of hepatocyte PPARγ, which will be tested by assessing liver, heart, muscle and adipose tissue uptake of radio-labeled TAG delivered by oral gavage or iv (to factor out changes in intestinal uptake). The results derived from this project will have an impact in the field because they will define the role of hepatocyte PPARγ and its downstream mechanisms in: 1) the development of diet-induced steatosis and NASH; 2) the dysregulation of metabolic function in NASH; 3) the contribution to hepatic lipid composition to insulin sensitivity and liver disease progression; and 4) the regulation of lipid homeostasis by controlling intestinal lipid absorption and/or tissue-specific postprandial TAG clearance. These results could lead to the development of drugs that block prosteatotic actions of hepatocyte PPARγ that could be used alone or in combination with other therapies to prevent and reverse NASH.

摘要：非酒精性脂肪肝（NAFLD）包括非酒精性脂肪肝（NAFL/脂肪变性） 到非酒精性脂肪性肝炎（NASH）。虽然简单的脂肪变性可能是“良性的”，但它是一种独立的风险 NASH 发展的因素。噻唑烷二酮类 (TZD) 是 PPARγ 激动剂，用于减少脂肪变性 患有 NASH 的糖尿病患者。然而，TZD 对脂肪变性的影响有限，并且对纤维化没有任何解决作用。 TZD 的抗脂肪变作用可能是由于人类和小鼠模型中胰岛素抵抗的降低。 然而，TZD 介导的肝细胞 PPARγ 激活可能抵消 TZD 假定的抗脂肪生成作用 并防止纤维化的任何减少。这是基于以下观察：1) 肝脏 PPARγ NAFLD 急剧增加； 2) TZD 以肝细胞 PPARγ 依赖性方式加剧脂肪变性 老鼠； 3) 临床上，TZD 的抗脂肪作用仅限于降低胰岛素抵抗。到 迄今为止，肝细胞 PPARγ 调节的脂质代谢对 NAFLD 的影响尚不清楚。所以 我们使用腺相关病毒敲低了成年 PPARγfl/fl 小鼠的肝细胞 PPARγ (>99.5%) 仅在肝细胞中表达 Cre 重组酶的载体 (AAV8-TBGp-Cre)。肝细胞 PPARγ 丢失 减少饮食引起的脂肪变性，因此在 SA#1 研究中建议确定如何减少 肝细胞 PPARγ 可预防饮食诱发的 NAFLD。我们假设 Cd36 介导的 FA 减少 肝细胞 PPARγ 丢失后观察到的摄取和/或 Mogat1 介导的 FA 再酯化对于 脂肪变性的减少和 NASH 的后续发展。为了检验这一假设，成年 PPARγfl/fl 小鼠 将喂食高脂肪、高胆固醇、高蔗糖饮食 (HF-HC-HSD)，已知会诱发脂肪变性（8 周 饮食）和 NASH（27 周饮食）。肝细胞 PPARγ 将被敲低，无论是否恢复 Cd36（FA 转位酶）或 Mogat1（单酰基甘油酰基转移酶）。肝脏 FA 摄取、MOGAT 活性、FA 三酰基甘油（TAG）、二酰基甘油（DAG）和单酰基甘油（MAG）的组成]，基因表达 并对肝脏和全身代谢病理生理学进行评估。尽管肝细胞 PPARγ 丢失 脂肪变性减少，则导致餐后血脂异常。因此，在 SA#2 研究中建议确定 肝细胞 PPARγ 丢失后促进餐后血脂异常的机制。我们 假设与肝细胞 PPARγ 特异性丢失相关的血脂异常是由于肠道增强 脂肪吸收通过给小鼠喂食含有不可吸收脂肪的饮食或口服给药后进行测试 泰洛沙泊存在下的放射性标记 TAG。我们还假设组织特异性 TAG 的变化 肝细胞 PPARγ 丢失后，摄取会受到损害，这将通过评估肝脏、心脏、肌肉和 脂肪组织通过口服或静脉注射方式摄取放射性标记的 TAG（以排除肠道变化） 吸收）。该项目的结果将在该领域产生影响，因为它们将定义 肝细胞 PPARγ 及其下游机制：1）饮食诱导的脂肪变性和 非酒精性脂肪性肝炎； 2）NASH代谢功能失调； 3）对肝脏脂质成分的贡献 胰岛素敏感性和肝病进展； 4）通过控制脂质稳态的调节 肠道脂质吸收和/或组织特异性餐后 TAG 清除。这些结果可能导致 开发阻断肝细胞 PPARγ 的前列腺增生作用的药物，可单独使用或联合使用 与其他疗法联合使用可预防和逆转 NASH。

项目成果

GH directly inhibits steatosis and liver injury in a sex-dependent and IGF1-independent manner.

• DOI: 10.1530/joe-20-0326
• 发表时间: 2021-01
• 期刊: The Journal of endocrinology
• 作者: Sarmento-Cabral A;Del Rio-Moreno M;Vazquez-Borrego MC;Mahmood M;Gutierrez-Casado E;Pelke N;Guzman G;Subbaiah PV;Cordoba-Chacon J;Yakar S;Kineman RD
• 通讯作者: Kineman RD