title: The timeline of metalloprotease events during oligofructose induced equine laminitis development.
abstract: BACKGROUND
  The role of matrix metalloproteases (MMPs) and the timeline of proteolysis during laminitis development are incompletely understood.
  
  
  OBJECTIVE
  To determine the temporal progression of selected MMPs and protease regulators during laminitis development.
  
  
  METHODS
  Five clinically normal Standardbred horses received, via nasogastric intubation, an oligofructose (OF) bolus (10 g/kg bwt). Laminitis induction proceeded for 48 h followed by euthanasia. Lamellar biopsies were obtained prior to dosing and at intervals during the treatment period for analysis (12, 18, 24, 30 and 36 h and at 48 h following euthanasia). Tissue samples were analysed by real-time PCR, zymography and western blotting.
  
  
  RESULTS
  Activation of proMMP-2 occurs either simultaneously or at least 12 h following lamellar basement membrane (BM) damage, while no activation of proMMP-9 is seen during OF laminitis induction. Aggrecanase gene expression increased initially at 12-18 h post OF dosing, similar to BM changes. Gene expression of TIMP-2, a MMP regulator, decreases during laminitis development.
  
  
  CONCLUSIONS
  The MMP-2/MT1-MMP complex may not play a major role in initiating lamellar BM damage. Aggrecanase and TIMP-2 gene expression appear related to BM lamellar changes.
  
  
  CONCLUSIONS
  MMPs, historically thought to cause laminitis, do not appear to play an initiating role in the lamellar lesion. Other host derived proteases and degradation of alternative lamellar matrix components need to be considered.
authors.affiliation: The Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Australia. michelle.visser@utoronto.ca
authors.forename: M B
authors.initials: MB
authors.lastname: Visser
authors.forename: C C
authors.initials: CC
authors.lastname: Pollitt
mesh_terms: D000818:Animals; D005534:Foot Diseases / Q000139:chemically induced / Q000662:veterinary*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006724:Hoof and Claw / Q000473:pathology*; D006734:Horse Diseases / Q000139:chemically induced* / Q000378:metabolism; D006736:Horses; D007249:Inflammation / Q000139:chemically induced / Q000662:veterinary*; D045726:Metalloproteases / Q000235:genetics / Q000378:metabolism*; D009844:Oligosaccharides / Q000633:toxicity*; D013997:Time Factors
chemical_list: D009844:Oligosaccharides; C120489:oligofructose; D045726:Metalloproteases