title: The importance of the interaction between hepatocyte and hepatic stellate cells in fibrogenesis induced by fatty accumulation.
abstract: OBJECTIVE
  Non-alcoholic fatty liver disease is characterized by an initial accumulation of triglycerides that can progress to non-alcoholic steatohepatitis, which can ultimately evolve to cirrhosis and hepatocellular carcinoma. Hepatic stellate cells play a key role in liver fibrogenesis by an increased activation and an altered profile of genes involved in the turnover of extracellular matrix components. To reproduce in-vitro the functional cell connections observed in vivo it is essential to consider cell-to-cell proximity and interaction. The aim of this study was to determine the response to free fatty acids in a simultaneous co-culture model of hepatocytes and hepatic stellate cells.
  
  
  METHODS
  Simultaneous co-culture model and monoculture of each cell type (control) were exposed to FFA for 24 up to 144 h. Quantification of steatosis; stellate cell activation; assessment of fibrogenic response; expression and activity of metalloproteinases as well as collagen biosynthesis were evaluated.
  
  
  RESULTS
  Free fatty acids induced comparable steatosis in simultaneous co-culture and monoculture. However, the activation of the stellate cells assessed by alpha-smooth muscle actin expression is greater when cells were in close contact. Furthermore, a time-dependent increment of tissue inhibitor metalloproteinase-2 protein was observed, which was inversely correlated with protein expression and activity of matrix-metalloproteinases, suggesting enhanced collagen biosynthesis. This behavior was absent in cell monoculture.
  
  
  CONCLUSIONS
  These data indicate that cell-to-cell proximity between hepatocytes and stellate cells is necessary for the initiation of the fibrotic process.
authors.affiliation: Fondazione Italiana Fegato, Centro Studi Fegato, Area Science Park Basovizza Bldg. Q SS14 Km 163.5, 34149 Trieste, Italy.
authors.forename: Pablo J
authors.initials: PJ
authors.lastname: Giraudi
authors.affiliation: Fondazione Italiana Fegato, Centro Studi Fegato, Area Science Park Basovizza Bldg. Q SS14 Km 163.5, 34149 Trieste, Italy; Liver Research Unit, Médica Sur Clinic & Foundation, Puente de Piedra 150, Col. Toriello Guerra, Tlalpan, C.P. 14050 Mexico City, Mexico.
authors.forename: Varenka J Barbero
authors.initials: VJ
authors.lastname: Becerra
authors.affiliation: Fondazione Italiana Fegato, Centro Studi Fegato, Area Science Park Basovizza Bldg. Q SS14 Km 163.5, 34149 Trieste, Italy.
authors.forename: Veronica
authors.initials: V
authors.lastname: Marin
authors.affiliation: Fondazione Italiana Fegato, Centro Studi Fegato, Area Science Park Basovizza Bldg. Q SS14 Km 163.5, 34149 Trieste, Italy; Liver Research Unit, Médica Sur Clinic & Foundation, Puente de Piedra 150, Col. Toriello Guerra, Tlalpan, C.P. 14050 Mexico City, Mexico.
authors.forename: Norberto C
authors.initials: NC
authors.lastname: Chavez-Tapia
authors.affiliation: Fondazione Italiana Fegato, Centro Studi Fegato, Area Science Park Basovizza Bldg. Q SS14 Km 163.5, 34149 Trieste, Italy; Department of Medical Sciences, University of Trieste, 34100 Trieste, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Tiribelli
authors.affiliation: Fondazione Italiana Fegato, Centro Studi Fegato, Area Science Park Basovizza Bldg. Q SS14 Km 163.5, 34149 Trieste, Italy. Electronic address: natalia.rosso@csf.units.it.
authors.forename: Natalia
authors.initials: N
authors.lastname: Rosso
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D018920:Coculture Techniques; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects* / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D055166:Hepatic Stellate Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007124:Immunoenzyme Techniques; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D008103:Liver Cirrhosis / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology*; D020778:Matrix Metalloproteinase 2 / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics / Q000378:metabolism
chemical_list: D005230:Fatty Acids, Nonesterified; D012333:RNA, Messenger; C560823:TIMP2 protein, human; D019716:Tissue Inhibitor of Metalloproteinase-2; D003094:Collagen; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2
keywords: Extracellular matrix turnover; Fibrogenesis; Hepatic stellate cells; Hepatocytes; Steatosis