title: Tumor necrosis factor alpha induces human atrial myofibroblast proliferation, invasion and MMP-9 secretion: inhibition by simvastatin.
abstract: OBJECTIVE
  Tumor necrosis factor alpha (TNFalpha) is implicated in myocardial remodeling, a process in which activated cardiac fibroblasts (myofibroblasts) secrete matrix-degrading metalloproteinases (MMPs) and undergo increased proliferation and invasion. Statins are cholesterol-lowering drugs that also have direct cellular effects, which may underlie their ability to reduce myocardial remodeling. This study investigated the effect of TNFalpha on human cardiac myofibroblast proliferation, invasion and MMP-9 secretion, and determined whether these properties were modulated by simvastatin.
  
  
  METHODS
  Human cardiac myofibroblasts were cultured from right atrial appendage. TNF receptor expression was quantified by immunoblotting. Cell proliferation, invasion, MMP-9 secretion and MMP-9 mRNA expression were determined by cell counting, Matrigel-coated modified Boyden chamber assays, gelatin zymography and RT-PCR, respectively.
  
  
  RESULTS
  Human atrial myofibroblasts expressed the TNF-RI and TNF-RII receptor subtypes. TNFalpha (1 ng/ml) induced a 23.1+/-3.9% increase in cell number after 4 days (P<0.001). Additionally, TNFalpha (1-10 ng/ml) significantly (P<0.01) increased myofibroblast invasion, with a concomitant increase in MMP-9 secretion, that was due to increased MMP-9 mRNA levels. Using TNF-R-specific neutralizing antibodies, we determined that these cellular effects of TNFalpha were predominantly TNF-RI-mediated. Simvastatin (0.1-10 mumol/l) concentration dependently inhibited TNFalpha-induced myofibroblast proliferation, invasion and MMP-9 secretion.
  
  
  CONCLUSIONS
  TNFalpha, acting predominantly via the TNF-R1 receptor, increased human atrial myofibroblast proliferation, invasion and MMP-9 secretion, all of which were inhibited by simvastatin. Inhibition of cytokine-induced cardiac myofibroblast activation by statins provides a rationale for their use in patients with cardiac pathologies characterized by adverse myocardial remodeling.
authors.affiliation: Institute for Cardiovascular Research, Academic Unit for Cardiovascular Medicine, Worsley Building, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Porter
authors.forename: Neil A
authors.initials: NA
authors.lastname: Turner
authors.forename: David J
authors.initials: DJ
authors.lastname: O'Regan
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Ball
mesh_terms: D002452:Cell Count; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D006325:Heart Atria; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D032386:Myoblasts, Cardiac / Q000166:cytology / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000032:analysis; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019821:Simvastatin / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D012333:RNA, Messenger; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D019821:Simvastatin; D020780:Matrix Metalloproteinase 9