title: Human articular chondrocytes express 15-lipoxygenase-1 and -2: potential role in osteoarthritis.
abstract: BACKGROUND
  15-Lipoxygenases and their metabolites have been shown to exhibit anti-inflammatory and immunomodulatory properties, but little is known regarding their expression and function in chondrocytes. The objective of this study was to evaluate the expression of 15-lipoxygenase-1 and -2 in human articular chondrocytes, and to investigate the effects of their metabolites 13(S)-hydroxy octadecadienoic and 15(S)-hydroxyeicosatetraenoic acids on IL-1beta-induced matrix metalloproteinase (MMP)-1 and MMP-13 expression.
  
  
  METHODS
  The expression levels of 15-lipoxygenase-1 and -2 were analyzed by reverse transcription PCR and Western blotting in chondrocytes, and by immunohistochemistry in cartilage. Chondrocytes or cartilage explants were stimulated with IL-1beta in the absence or presence of 13(S)-hydroxy octadecadienoic and 15(S)-hydroxyeicosatetraenoic acids, and the levels of MMP-1 and MMP-13 protein production and type II collagen cleavage were evaluated using immunoassays. The role of peroxisome proliferator-activated receptor (PPAR)gamma was evaluated using transient transfection experiments and the PPARgamma antagonist GW9662.
  
  
  RESULTS
  Articular chondrocytes express 15-lipoxygenase-1 and -2 at the mRNA and protein levels. 13(S)-hydroxy octadecadienoic and 15(S)-hydroxyeicosatetraenoic acids dose dependently decreased IL-1beta-induced MMP-1 and MMP-13 protein and mRNA expression as well as type II collagen cleavage. The effect on MMP-1 and MMP-13 expression does not require de novo protein synthesis. 13(S)-hydroxy octadecadienoic and 15(S)-hydroxyeicosatetraenoic acids activated endogenous PPARgamma, and GW9662 prevented their suppressive effect on MMP-1 and MMP-13 production, suggesting the involvement of PPARgamma in these effects.
  
  
  CONCLUSIONS
  This study is the first to demonstrate the expression of 15-lipoxygenase-1 and -2 in articular chondrocytes. Their respective metabolites, namely 13(S)-hydroxy octadecadienoic and 15(S)-hydroxyeicosatetraenoic acids, suppressed IL-1beta-induced MMP-1 and MMP-13 expression in a PPARgamma-dependent pathway. These data suggest that 15-lipoxygenases may have chondroprotective properties by reducing MMP-1 and MMP-13 expression.
authors.affiliation: Osteoarthritis Research Unit, Research Centre of the University of Montreal Hospital Center, Notre-Dame Hospital, Montreal, Quebec, Canada. nadir.chabane@umontreal.ca
authors.forename: Nadir
authors.initials: N
authors.lastname: Chabane
authors.forename: Nadia
authors.initials: N
authors.lastname: Zayed
authors.forename: Mohamed
authors.initials: M
authors.lastname: Benderdour
authors.forename: Johanne
authors.initials: J
authors.lastname: Martel-Pelletier
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Pelletier
authors.forename: Nicolas
authors.initials: N
authors.lastname: Duval
authors.forename: Hassan
authors.initials: H
authors.lastname: Fahmi
mesh_terms: D001093:Arachidonate 15-Lipoxygenase / Q000096:biosynthesis*; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000201:enzymology*; D019902:Chondrocytes / Q000201:enzymology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D007150:Immunohistochemistry; D008041:Linoleic Acids / Q000378:metabolism; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D053509:Matrix Metalloproteinase 13 / Q000378:metabolism; D010003:Osteoarthritis / Q000201:enzymology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D008041:Linoleic Acids; C095134:13-hydroxyeicosatetraenoic acid; C024348:13-hydroxy-9,11-octadecadienoic acid; D001093:Arachidonate 15-Lipoxygenase; D053509:Matrix Metalloproteinase 13; D020781:Matrix Metalloproteinase 1