title: Fibroblast activation protein alpha expression identifies activated fibroblasts after myocardial infarction.
abstract: BACKGROUND
  Fibroblast activation protein α (FAP) is a membrane-bound serine protease expressed by activated fibroblasts during wound healing in the skin. Expression of FAP after myocardial infarction (MI) and potential effects on cardiac wound healing are largely unknown.
  
  
  METHODS
  MI was induced in rats and FAP expression was analyzed at 3, 7 and 28 days post-MI by microarray, Western blot and immunohistochemistry. In human hearts after MI, a FAP(+) fibroblast population was identified, and characterized by immunohistochemistry for prolyl-4-hydroxylase β, α-smooth muscle actin, Thy-1 and vimentin. Signaling pathways leading to FAP expression were studied in human cardiac fibroblasts by Western blot and ELISA using TGFβ1, TGF-beta type I-receptor (TGFbR1)-inhibitor SB431542 or the MAPK-inhibitor U0126 as well as siRNA targeting SMAD2 and SMAD3. Finally, fibroblasts were assayed for FAP-dependent migration (modified Boyden-chamber), proliferation (BrdU-assay) and gelatinolytic activity by gelatin zymography.
  
  
  RESULTS
  In rats, FAP expression was increased after MI especially in the peri-infarct area peaking at 7 days post-MI. Co-localization analysis identified the majority of FAP(+) cells as activated proto-myofibroblasts and myofibroblasts. Concordantly, FAP(+) fibroblasts were abundant in ischemic tissue of human hearts after MI, but not in healthy control hearts. In vitro, FAP was induced by TGFβ1 via the canonical SMAD2/SMAD3 pathway. Depletion of FAP in fibroblasts reduced migratory capacity, while proliferation was not affected. Gelatin zymography revealed gelatinase activity by fibroblast-derived FAP.
  
  
  CONCLUSIONS
  In this study, we show for the first time the expression of FAP in activated fibroblasts after MI and its activation by TGFβ1. Effects of FAP on fibroblast migration and gelatinolytic activity indicate a potential role in cardiac wound healing and remodeling.
authors: Department of Cardiology and Angiology, Hannover Medical School, 30625 Hannover, Germany. Electronic address: tillmanns.jochen@mh-hannover.de.
authors: Jochen
authors: J
authors: Tillmanns
authors: Department of Medicine, University Hospital Wurzburg, 97080 Wurzburg, Germany.
authors: Daniel
authors: D
authors: Hoffmann
authors: Department of Cardiology and Angiology, Hannover Medical School, 30625 Hannover, Germany.
authors: Yasmin
authors: Y
authors: Habbaba
authors: Department of Cardiothoracic Surgery, Hannover Medical School, 30625 Hannover, Germany.
authors: Jan D
authors: JD
authors: Schmitto
authors: Department of Cardiology and Angiology, Hannover Medical School, 30625 Hannover, Germany.
authors: Daniel
authors: D
authors: Sedding
authors: Department of Cardiology and Angiology, Hannover Medical School, 30625 Hannover, Germany.
authors: Daniela
authors: D
authors: Fraccarollo
authors: Department of Cardiology and Angiology, Hannover Medical School, 30625 Hannover, Germany.
authors: Paolo
authors: P
authors: Galuppo
authors: Department of Cardiology and Angiology, Hannover Medical School, 30625 Hannover, Germany.
authors: Johann
authors: J
authors: Bauersachs
mesh_terms: D000818:Animals; D010450:Endopeptidases; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D018093:Gelatinases / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D007249:Inflammation / Q000235:genetics* / Q000473:pathology; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D009203:Myocardial Infarction / Q000235:genetics* / Q000473:pathology; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D058628:Myofibroblasts / Q000378:metabolism / Q000473:pathology; D051381:Rats; D012697:Serine Endopeptidases / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D014945:Wound Healing / Q000235:genetics; D000099222:betaIG-H3 Protein; D000099167:Fibroblast Activation Protein Alpha
chemical_list: D010450:Endopeptidases; D016326:Extracellular Matrix Proteins; D018093:Gelatinases; D008565:Membrane Proteins; D012697:Serine Endopeptidases; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein; D000099167:Fibroblast Activation Protein Alpha
keywords: Fibroblast activation protein α; Heart; Inflammation; Myocardial infarction; Myofibroblast; Wound healing