title: Macrophage secretory products induce an inflammatory phenotype in hepatocytes.
abstract: OBJECTIVE
  To investigate the influence of macrophages on hepatocyte phenotype and function.
  
  
  METHODS
  Macrophages were differentiated from THP-1 monocytes via phorbol myristate acetate stimulation and the effects of monocyte or macrophage-conditioned medium on HepG2 mRNA and protein expression determined. The in vivo relevance of these findings was confirmed using liver biopsies from 147 patients with hepatitis C virus (HCV) infection.
  
  
  RESULTS
  Conditioned media from macrophages, but not monocytes, induced a transient morphological change in hepatocytes associated with upregulation of vimentin (7.8 ± 2.5-fold, P = 0.045) and transforming growth factor (TGF)-β1 (2.6 ± 0.2-fold, P < 0.001) and downregulation of epithelial cadherin (1.7 ± 0.02-fold, P = 0.017) mRNA expression. Microarray analysis revealed significant upregulation of lipocalin-2 (17-fold, P < 0.001) and pathways associated with inflammation, and substantial downregulation of pathways related to hepatocyte function. In patients with chronic HCV, real-time polymerase chain reaction and immunohistochemistry confirmed an increase in lipocalin-2 mRNA (F0 1.0 ± 0.3, F1 2.2 ± 0.2, F2 3.0 ± 9.3, F3/4 4.0 ± 0.8, P = 0.003) and protein expression (F1 1.0 ± 0.5, F2 1.3 ± 0.4, F3/4 3.6 ± 0.4, P = 0.014) with increasing liver injury. High performance liquid chromatography-tandem mass spectrometry analysis identified elevated levels of matrix metalloproteinase (MMP)-9 in macrophage-conditioned medium, and a chemical inhibitor of MMP-9 attenuated the change in morphology and mRNA expression of TGF-β1 (2.9 ± 0.2 vs 1.04 ± 0.1, P < 0.001) in macrophage-conditioned media treated HepG2 cells. In patients with chronic HCV infection, hepatic mRNA expression of CD163 (F0 1.0 ± 0.2, F1/2 2.8 ± 0.3, F3/4 5.3 ± 1.0, P = 0.001) and MMP-9 (F0 1.0 ± 0.4, F1/2 2.8 ± 0.3, F3/4 4.1 ± 0.8, P = 0.011) was significantly associated with increasing stage of fibrosis.
  
  
  CONCLUSIONS
  Secreted macrophage products alter the phenotype and function of hepatocytes, with increased expression of inflammatory mediators, suggesting that hepatocytes actively participate in liver injury.
authors.affiliation: Centre for Liver Disease Research, School of Medicine, The University of Queensland, Princess Alexandra Hospital, Brisbane 4102, Queensland, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Melino
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Gadd
authors.forename: Gene V
authors.initials: GV
authors.lastname: Walker
authors.forename: Richard
authors.initials: R
authors.lastname: Skoien
authors.forename: Helen D
authors.initials: HD
authors.lastname: Barrie
authors.forename: Dinesh
authors.initials: D
authors.lastname: Jothimani
authors.forename: Leigh
authors.initials: L
authors.lastname: Horsfall
authors.forename: Alun
authors.initials: A
authors.lastname: Jones
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Sweet
authors.forename: Gethin P
authors.initials: GP
authors.lastname: Thomas
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Clouston
authors.forename: Julie R
authors.initials: JR
authors.lastname: Jonsson
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Powell
mesh_terms: D000209:Acute-Phase Proteins / Q000502:physiology; D015703:Antigens, CD / Q000502:physiology; D015214:Antigens, Differentiation, Myelomonocytic / Q000502:physiology; D020869:Gene Expression Profiling; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000502:physiology*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D000071068:Lipocalin-2; D054834:Lipocalins / Q000502:physiology; D008103:Liver Cirrhosis / Q000378:metabolism; D008264:Macrophages / Q000502:physiology*; D020780:Matrix Metalloproteinase 9 / Q000502:physiology; D010641:Phenotype; D011518:Proto-Oncogene Proteins / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000502:physiology; D000098902:CD163 Antigen
chemical_list: D000209:Acute-Phase Proteins; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D000098902:CD163 Antigen; D018836:Inflammation Mediators; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D020780:Matrix Metalloproteinase 9