title: Differential transcriptional activation of matrix metalloproteinase-2 and membrane type-1 matrix metalloproteinase by experimental deep venous thrombosis and thrombin.
abstract: OBJECTIVE
  Resolution of deep venous thrombosis (DVT) is involved in the pathogenesis of postthrombotic syndrome. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that are critical in angiogenesis and tissue remodeling. We hypothesized that MMP-2 and its membrane-bound activator membrane type-1 matrix metalloproteinase (MT1-MMP) expression would be expressed and activated during the resolution of DVT.
  
  
  METHODS
  DVT was generated by caval ligation in wild-type and MMP-2 transgenic reporter mice. Ligated and sham-operated (control) cavae were analyzed for MMP-2 transcription (beta-galactosidase activity in MMP-2 reporter mice) and MT1-MMP mRNA by real-time polymerase chain reaction. MMP-2 activity was determined by zymography, and immunohistochemical staining for beta-galactosidase and MT1-MMP protein was used to localize expression. Human umbilical vascular endothelial cells (HUVEC) were treated with 10 U/mL thrombin and MMP-2 and MT1-MMP mRNA levels and MMP-2 activity was determined.
  
  
  RESULTS
  MMP-2 activity increased 71% (n = 5, P < .05) at day 8 in ligated vs control cavae by zymography. beta-galactosidase activity showed a 1.2-fold (n = 8, P < .05) and 1.7-fold (n = 8, P < .05) induction in MMP-2 transcription at day 3 and day 8, respectively. No significant MT1-MMP gene induction was seen at day 3 in ligated vs control cavae, but MT1-MMP mRNA was upregulated 2.5-fold (n = 8, P < .05) in ligated cavae at day 8. Immunohistochemical staining localized MMP-2 and MT1-MMP expression to the vein wall and cellular infiltrates of the thrombus. Thrombin-treated HUVEC showed differential responses of MMP-2 and MT1-MMP. Zymography of conditioned media and cell lysates illustrated a 220% (152.6 +/- 8.6 vs 69.445 +/- 5.46 pixels/unit area, n = 5, P < .05) and 150% (74.1 +/- 7.3 vs 49.2 +/- 5.7 pixels/unit area, n = 5, P < .05) increases in MMP-2 activity respectively. MMP-2 mRNA levels were downregulated 30% (0.48 +/- 0.023 vs 0.63 +/- 0.035 copies of MMP-2 mRNA/copy GAPDH, n = 5, P < .05), whereas MT1-MMP message was upregulated 250% (0.147 +/- 0.009 vs 0.059 +/- 0.005 copies of MT1-MMP mRNA/copy GAPDH, n = 5, P < .05).
  
  
  CONCLUSIONS
  Resolution of DVT is associated with increased MMP-2 transcription and activity as well as MT1-MMP expression. Thrombin may mediate the increase in MT1-MMP noted in DVT. This is the first article studying MMP-2 and MT1-MMP transcription in DVT. These findings add DVT resolution to the class of inflammatory and fibrotic disorders in which transcriptional activation of the MT1-MMP/MMP-2 genes occurs and identify a potential therapeutic target to modulate this clinically relevant process.
  
  
  CONCLUSIONS
  Postthrombotic syndrome remains a significant clinical problem after deep venous thrombosis (DVT), but the cellular and molecular mechanisms involved in thrombus resolution and vein wall fibrosis remain undefined. Matrix metalloproteinase (MMP) enzymes are critical to cell migration and matrix breakdown. We identify gene transcription and activity of two MMP isoforms, MMP-2 and MMP-14 (membrane type MMP 1, MT1-MMP) in the resolution phase of experimental DVT and in thrombin-treated endothelial cells. These studies define new proteases potentially important to resolution of DVT and development of postthrombotic syndrome.
authors.affiliation: Division of Vascular Surgery, University of California San Francisco, USA.
authors.forename: Sia
authors.initials: S
authors.lastname: Dahi
authors.forename: Jackie G
authors.initials: JG
authors.lastname: Lee
authors.forename: David H
authors.initials: DH
authors.lastname: Lovett
authors.forename: Rajabrata
authors.initials: R
authors.lastname: Sarkar
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology; D007124:Immunoenzyme Techniques; D053511:Matrix Metalloproteinase 14; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013917:Thrombin / Q000494:pharmacology*; D015533:Transcriptional Activation; D020246:Venous Thrombosis / Q000188:drug therapy* / Q000201:enzymology*; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: C507096:Mmp14 protein, mouse; D001616:beta-Galactosidase; D013917:Thrombin; D053504:Matrix Metalloproteinases, Membrane-Associated; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14