title: Oxidative stress is activated by free fatty acids in cultured human hepatocytes.
abstract: BACKGROUND
  Nonalcoholic fatty liver disease (NAFLD) is strongly associated to oxidative stress, metabolic syndrome, and cardiovascular risk. Hepatocytes overloaded with fatty acids (FA) could generate substances that interfere with endothelial function, providing a potential explanation for this association. We have investigated the response of cultured human hepatoblastoma cells (Hep-G2) that were exposed to FA by measuring markers of oxidative stress and thrombosis and expression of the insulin receptor.
  
  
  METHODS
  Hep-G2 cells were conditioned with a mixture of FA with or without N-acetyl-L-cysteine (NAC), glutathione (GSH), or adiponectin (ADN). After 7 days, we measured intracellular GSH (iGSH), nitric oxide (NO), malondialdehyde (MDA), and tissue plasminogen inhibitor-1 (PAI-1). Real-time polymerase chain reaction (PCR) was used to determine gene expression of inducible nitric oxide synthase (iNOS) and insulin receptor (INS-R).
  
  
  RESULTS
  Exposure to FA decreased iGSH and NO levels in Hep-G2 cells and increased MDA and PAI-1 production. Gene expression of iNOS and INS-R in Hep-G2 cells was decreased by exposure to FA. Co-incubation with NAC and GSH prevented the change of iNOS mRNA levels, but not of INS-R; co-incubation with ADN restored the gene expression of INS-R, but not of i-NOS. ADN prevented also the FA-induced increase in MDA in cultured human endothelial cells.
  
  
  CONCLUSIONS
  Exposure to FA activates oxidative stress and production of prothrombotic markers and decreases expression of insulin receptors in cultured human hepatocytes. These effects of FA are partially prevented by ADN and might contribute to the increased cardiovascular risk in patients with NAFLD and metabolic syndrome.
authors.affiliation: Liver and Hypertension Unit, Department of Pathology and Experimental and Clinical Medicine, University of Udine, Udine, Italy. soardo.giorgio.@aoud.sanita.fvg.it
authors.forename: Giorgio
authors.initials: G
authors.lastname: Soardo
authors.forename: Debora
authors.initials: D
authors.lastname: Donnini
authors.forename: Liana
authors.initials: L
authors.lastname: Domenis
authors.forename: Cristiana
authors.initials: C
authors.lastname: Catena
authors.forename: Daniele
authors.initials: D
authors.lastname: De Silvestri
authors.forename: Dario
authors.initials: D
authors.lastname: Cappello
authors.forename: Alessia
authors.initials: A
authors.lastname: Dibenedetto
authors.forename: Alessia
authors.initials: A
authors.lastname: Carnelutti
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Bonasia
authors.forename: Claudio
authors.initials: C
authors.lastname: Pagano
authors.forename: Leonardo A
authors.initials: LA
authors.lastname: Sechi
mesh_terms: D052242:Adiponectin / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D002478:Cells, Cultured; D005227:Fatty Acids / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005234:Fatty Liver / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D018197:Hepatoblastoma / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D065626:Non-alcoholic Fatty Liver Disease; D018384:Oxidative Stress; D011972:Receptor, Insulin / Q000378:metabolism; D012306:Risk; D013927:Thrombosis / Q000378:metabolism
chemical_list: D052242:Adiponectin; D000975:Antioxidants; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D011972:Receptor, Insulin; D005978:Glutathione