title: Effect of intracellular lipid accumulation in a new model of non-alcoholic fatty liver disease.
abstract: BACKGROUND
  In vitro exposure of liver cells to high concentrations of free fatty acids (FFA) results in fat overload which promotes inflammatory and fibrogenic response similar to those observed in patients with Non-Alcoholic Fatty Liver Disease (NAFLD) and Non-Alcoholic Steatohepatitis (NASH). Since the mechanisms of this event have not been fully characterized, we aimed to analyze the fibrogenic stimuli in a new in vitro model of NASH.
  
  
  METHODS
  HuH7 cells were cultured for 24 h in an enriched medium containing bovine serum albumin and increasing concentrations of palmitic and oleic acid at a molar ratio of 1:2 (palmitic and oleic acid, respectively). Cytotoxic effect, apoptosis, oxidative stress, and production of inflammatory and fibrogenic cytokines were measured.
  
  
  RESULTS
  FFA induces a significant increment in the intracellular content of lipid droplets. The gene expression of interleukin-6, interleukin-8 and tumor necrosis factor alpha was significantly increased. The protein level of interleukin-8 was also increased. Intracellular lipid accumulation was associated to a significant up-regulation in the gene expression of transforming growth factor beta 1, alpha 2 macroglobulin, vascular endothelial growth factor A, connective tissue growth factor, insulin-like growth factor 2, thrombospondin 1. Flow cytometry analysis demonstrated a significant increment of early apoptosis and production of reactive oxygen species.
  
  
  CONCLUSIONS
  The exposure of hepatocytes to fatty acids elicits inflammation, increase of oxidative stress, apoptosis and production of fibrogenic cytokines. These data support a primary role of FFA in the pathogenesis of NAFLD and NASH.
authors.affiliation: Fondazione Italiana Fegato- Centro Studi Fegato, AREA SCIENCE Park Basovizza, Bldg Q, Trieste, Italy. khavez@gmail.com
authors.forename: Norberto C
authors.initials: NC
authors.lastname: Chavez-Tapia
authors.forename: Natalia
authors.initials: N
authors.lastname: Rosso
authors.forename: Claudio
authors.initials: C
authors.lastname: Tiribelli
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005230:Fatty Acids, Nonesterified / Q000009:adverse effects / Q000494:pharmacology*; D005234:Fatty Liver / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology*; D022781:Hepatocytes / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D066298:In Vitro Techniques; D050356:Lipid Metabolism / Q000187:drug effects*; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D008954:Models, Biological; D065626:Non-alcoholic Fatty Liver Disease; D019301:Oleic Acid / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D019308:Palmitic Acid / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D016207:Cytokines; D005230:Fatty Acids, Nonesterified; D017382:Reactive Oxygen Species; D019301:Oleic Acid; D019308:Palmitic Acid