Hepatic free cholesterol accumulates in obese, diabetic mice and causes nonalcoholic steatohepatitis
Date
2011
Authors
Van Rooyen, Derrick
Larter, Claire
Haigh, W Geoffrey
Yeh, Matthew
Ioannou, George
Kuver, Rahul
Lee, Sum P
Teoh, Narcissus
Farrell, Geoffrey
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W B Saunders Co
Abstract
Background & Aims: Type 2 diabetes and nonalcoholic steatohepatitis (NASH) are associated with insulin resistance and disordered cholesterol homeostasis. We investigated the basis for hepatic cholesterol accumulation with insulin resistance and its relevance to the pathogenesis of NASH. Methods: Alms1 mutant (foz/foz) and wild-type NOD.B10 mice were fed high-fat diets that contained varying percentages of cholesterol; hepatic lipid pools and pathways of cholesterol turnover were determined. Hepatocytes were exposed to insulin concentrations that circulate in diabetic foz/foz mice. Results: Hepatic cholesterol accumulation was attributed to up-regulation of low-density lipoprotein receptor via activation of sterol regulatory element binding protein 2 (SREBP-2), reduced biotransformation to bile acids, and suppression of canalicular pathways for cholesterol and bile acid excretion in bile. Exposing primary hepatocytes to concentrations of insulin that circulate in diabetic Alms1 mice replicated the increases in SREBP-2 and low-density lipoprotein receptor and suppression of bile salt export pump. Removing cholesterol from diet prevented hepatic accumulation of free cholesterol and NASH; increasing dietary cholesterol levels exacerbated hepatic accumulation of free cholesterol, hepatocyte injury or apoptosis, macrophage recruitment, and liver fibrosis. Conclusions: In obese, diabetic mice, hyperinsulinemia alters nuclear transcriptional regulators of cholesterol homeostasis, leading to hepatic accumulation of free cholesterol; the resulting cytotoxicity mediates transition of steatosis to NASH.
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Keywords: bile acid; cholesterol; insulin; low density lipoprotein receptor; sterol regulatory element binding protein 2; animal cell; animal experiment; animal model; animal tissue; article; bile; biotransformation; controlled study; diabetes mellitus; enzyme acti Bsep; Lipotoxicity; Liver Damage; LRH-1
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Gastroenterology
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Journal article
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2037-12-31
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