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Mechanism of basic calcium phosphate crystal-stimulated matrix metalloproteinase-13 expression by osteoarthritic synovial fibroblasts: inhibition by prostaglandin E2
  1. E S Molloy1,
  2. M P Morgan1,
  3. G A Doherty2,
  4. B McDonnell1,
  5. J O’Byrne3,
  6. D J Fitzgerald2,
  7. G M McCarthy1,2,3,4
  1. 1
    Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
  2. 2
    Conway Institute, University College Dublin, Ireland
  3. 3
    National Orthopaedic Hospital, Cappagh, Dublin, Ireland
  4. 4
    Department of Rheumatology, Mater Misericordiae University Hospital, Dublin, Ireland
  1. E S Molloy, Department of Rheumatic and Immunologic Diseases, Desk A50, Cleveland Clinic Foundation, Cleveland, OH 44195, USA; eamonn.molloy{at}ireland.com

Abstract

Objective: To determine the mechanism of matrix metalloproteinase (MMP)-13 upregulation in osteoarthritic synovial fibroblasts (OASF) in response to stimulation with basic calcium phosphate (BCP) crystals and to investigate the effect of prostaglandin (PG)E2 on BCP crystal-stimulated MMP expression.

Methods: Primary OASF were stimulated with BCP crystals; mRNA expression was measured by real-time reverse transcription–polymerase chain reaction and protein levels were assessed by Western blotting.

Results: BCP crystals upregulated MMP-13 mRNA expression over 20-fold and increased MMP-13 protein production in OASF. BCP crystal-stimulated MMP-13 mRNA expression was blocked by inhibition of the extracellular regulated kinase (ERK1/2) and p38 mitogen activated protein kinase (MAPK) pathways and inhibition of the activation of nuclear factor κB. Addition of exogenous PGE2 downregulated BCP crystal-stimulated MMP-13 expression. In contrast, PGE2 upregulated, and had no effect, on BCP crystal stimulated MMP-3 and MMP-1 mRNA expression, respectively. These effects of PGE2 were diminished by L-161,982, a selective EP4 receptor antagonist, and mimicked by CAY10399, a selective EP2 receptor agonist, and forskolin, an adenylate cyclase activator.

Conclusions: These data suggest that BCP crystal induction of MMP-13 expression may involve the ERK1/2 and p38 MAPK pathways and activation of nuclear factor κB; this upregulation of MMP-13 may contribute to the accelerated cartilage breakdown in BCP crystal-associated osteoarthritis. PGE2 had contrasting effects on BCP crystal-stimulated MMP-3 and MMP-13 mRNA expression, mediated in an EP2/EP4/cAMP-dependent manner, suggesting that PGE2 may have beneficial as well as deleterious effects in BCP crystal-associated osteoarthritis.

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Footnotes

  • Competing interests: None.

  • Funding: This work was funded by the Health Research Board, Wellcome Trust and the PRTLI Cycle III.

  • ▸ Additional figure (fig 7) is published online only at http://ard.bmj.com/content/vol67/issue12

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