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: 10082448
• 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/10082448
• 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; 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; 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 - 非酒精性脂肪肝病（NAFLD）包括非酒精性脂肪肝（NAFL/Steatosis） 非酒精性脂肪性肝炎（NASH）。尽管简单的脂肪变性可以是“良性”，但它是独立的风险 纳什开发的因素。噻唑烷二酮（TZD）是用于减少脂肪变性的PPARγ激动剂 糖尿病患者纳什。但是，TZD对脂肪变性的影响是有限的，而没有任何纤维化的分辨率。 TZD的抗逆动作作用可能是由于人类和小鼠模型的胰岛素抵抗降低所致。 但是，TZD介导的肝细胞PPARγ的激活可能会抵消TZD的假定抗抗病作用 并防止纤维化减少。这是基于以下观察结果：1）肝PPARγ NAFLD急剧增加； 2）以肝细胞PPARγ依赖性方式加剧脂肪变性 小鼠； 3）在临床上，TZD的抗抗源性作用仅限于胰岛素抵抗的降低。到 日期，对肝细胞PPARγ调节的脂质代谢对NAFLD的影响很差。所以 我们已经使用腺相关病毒击倒成年PPARγFL/FL小鼠的肝细胞PPARγ（> 99.5％） 仅在肝细胞（AAV8-TBGP-CRE）中表达CRE重组酶的载体。肝细胞PPARγ的丧失 饮食诱导的脂肪变性减少，因此提出了SA＃1研究，以确定如何丧失 肝细胞PPARγ可防止饮食诱导的NAFLD。我们假设CD36介导的FA的减少 摄取和/或MOGAT1介导的FA重新酯化，在肝细胞PPARγ丢失后观察到，对于 脂肪变性的减少和随后的NASH发展。为了检验该假设，成年PPARγFL/FL小鼠 将喂养高脂肪，高胆固醇，高蔗糖饮食（HF-HC-HSD），已知会诱发脂肪变性（8周的8周 饮食）和纳什（饮食27周）。肝细胞PPARγ将被击倒，没有或恢复 CD36（FA易位酶）或MOGAT1（单酰甘油酰基转移酶）。肝FA摄取，莫加特活动，fa 三酰基甘油（TAG），二酰基甘油（DAG）和单酰甘油（MAG）的组成，基因表达 将评估肝脏和全身代谢病理生理学。尽管肝细胞PPARγ的丧失 减少脂肪变性，导致餐后血脂异常。因此，提出了SA＃2研究以确定 肝细胞PPARγ丧失后促进餐后血脂异常的机制。我们 假设与肝细胞PPARγ的特异性损失相关的血脂异常是由于肠道增强引起的 脂肪滥用，将通过喂养含有不可吸收脂肪或口服递送后的饮食来测试 在Tyloxapol存在下的无线电标签。我们还假设组织特异性标签的变化 肝细胞PPARγ丧失后，摄取受损，该肝细胞PPARγ将通过评估肝脏，心脏，肌肉和 通过口服膨胀或IV传递的无线电标签标签的脂肪组织吸收（以肠道变化 吸收）。从该项目得出的结果将对现场产生影响，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 纳什； 2）NASH代谢功能的失调； 3）对肝脂质成分的贡献 胰岛素敏感性和肝病进展； 4）通过控制脂质稳态的调节 肠道脂质抽象和/或组织特异性的餐前标签清除率。这些结果可能导致 开发可以阻止可以单独或在 与其他疗法结合使用，以预防和逆转NASH。