Hypoxia aggravates non-alcoholic steatohepatitis in mice lacking hepatocellular PTEN

Piguet, Anne-Christine; Stroka, Deborah; Zimmermann, Arthur; Dufour, Jean-François (2010). Hypoxia aggravates non-alcoholic steatohepatitis in mice lacking hepatocellular PTEN. Clinical science, 118(6), pp. 401-10. London: Portland 10.1042/CS20090313

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The metabolic disorders that predispose patients to NASH (non-alcoholic steatohepatitis) include insulin resistance and obesity. Repeated hypoxic events, such as occur in obstructive sleep apnoea syndrome, have been designated as a risk factor in the progression of liver disease in such patients, but the mechanism is unclear, in particular the role of hypoxia. Therefore we studied the influence of hypoxia on the development and progression of steatohepatitis in an experimental mouse model. Mice with a hepatocellular-specific deficiency in the Pten (phosphatase and tensin homologue deleted on chromosome 10) gene, a tumour suppressor, were exposed to a 10% O2 (hypoxic) or 21% O2 (control) atmosphere for 7 days. Haematocrit, AST (aspartate aminotransferase), glucose, triacylglycerols (triglycerides) and insulin tolerance were measured in blood. Histological lesions were quantified. Expression of genes involved in lipogenesis and mitochondrial beta-oxidation, as well as FOXO1 (forkhead box O1), hepcidin and CYP2E1 (cytochrome P450 2E1), were analysed by quantitative PCR. In the animals exposed to hypoxia, the haematocrit increased (60+/-3% compared with 50+/-2% in controls; P<0.01) and the ratio of liver weight/body weight increased (5.4+/-0.2% compared with 4.7+/-0.3% in the controls; P<0.01). Furthermore, in animals exposed to hypoxia, steatosis was more pronounced (P<0.01), and the NAS [NAFLD (non-alcoholic fatty liver disease) activity score] (8.3+/-2.4 compared with 2.3+/-10.7 in controls; P<0.01), serum AST, triacylglycerols and glucose were higher. Insulin sensitivity decreased in mice exposed to hypoxia relative to controls. The expression of the lipogenic genes SREBP-1c (sterol-regulatory-element-binding protein-1c), PPAR-gamma (peroxisome-proliferator-activated receptor-gamma), ACC1 (acetyl-CoA carboxylase 1) and ACC2 (acetyl-CoA carboxylase 2) increased significantly in mice exposed to hypoxia, whereas mitochondria beta-oxidation genes [PPAR-alpha (peroxisome-proliferator-activated receptor-alpha) and CPT-1 (carnitine palmitoyltransferase-1)] decreased significantly. In conclusion, the findings of the present study demonstrate that hypoxia alone aggravates and accelerates the progression of NASH by up-regulating the expression of lipogenic genes, by down-regulating genes involved in lipid metabolism and by decreasing insulin sensitivity.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Gastro-intestinal, Liver and Lung Disorders (DMLL) > Clinic of Visceral Surgery and Medicine > Visceral Surgery 04 Faculty of Medicine > Service Sector > Institute of Pathology 04 Faculty of Medicine > Service Sector > Institute of Clinical Pharmacology and Visceral Research [discontinued]
UniBE Contributor:	Stroka, Deborah, Zimmermann, Arthur, Dufour, Jean-François
ISSN:	0143-5221
Publisher:	Portland
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:07
Last Modified:	05 Dec 2022 14:00
Publisher DOI:	10.1042/CS20090313
PubMed ID:	19832698
Web of Science ID:	000275476500010
URI:	https://boris.unibe.ch/id/eprint/98 (FactScience: 195749)