title: Phenyl N-tert-butylnitrone down-regulates interleukin-1 beta-stimulated matrix metalloproteinase-13 gene expression in human chondrocytes: suppression of c-Jun NH2-terminal kinase, p38-mitogen-activated protein kinase and activating protein-1.
abstract: Cytokine-mediated induction and overexpression of matrix metalloproteinases (MMPs) is recognized as an important factor in the pathogenesis of arthritis. Interleukin (IL)-1 beta is a proinflammatory cytokine that is known to superinduce the expression and production of MMP-13 in many cell types. Phenyl N-tert-butylnitrone (PBN), a spin trap agent, inhibited the IL-1 beta-induced expression of MMP-13 in human osteoarthritis (OA) chondrocytes. Down-regulation of MMP-13 expression correlated with the inhibition of mitogen-activated protein kinase (MAPK) subgroups c-Jun NH2-terminal kinase (JNK) and p38-MAPK activation, accumulation of phospho-c-jun, and the DNA binding activity of activating protein-1 (AP-1). Results of in vitro kinase assays showed that exogenously added PBN completely blocked the c-Jun phosphorylating activity of JNK. Interestingly, using in vitro kinase assay, we also found that chondrocyte p38-MAPK phosphorylate c-Jun and that PBN was not very effective in inhibiting c-Jun phosphorylating activity of p38-MAPK. In addition, PBN did not block the ATF-2 phosphorylating activity of p38-MAPK and Elk-1 phosphorylating activity of extracellular regulated kinase p44/p42 in vitro, indicating that PBN may act selectively to inhibit the phosphorylation of c-Jun in OA chondrocytes. Together, our results for the first time demonstrate that PBN suppresses the IL-1 beta-stimulated expression of MMP-13 in OA chondrocytes and that this was achieved by inhibiting the activation of JNK and AP-1. These results suggest that use of PBN or compounds derived from it may be of potential benefit in inhibiting signaling events associated with cartilage degradation in arthritis.
authors.affiliation: Department of Orthopedics, Case Western Reserve University, Cleveland, OH 44106-4946, USA.
authors.forename: Salahuddin
authors.initials: S
authors.lastname: Ahmed
authors.forename: Ayesha
authors.initials: A
authors.lastname: Rahman
authors.forename: Absarul
authors.initials: A
authors.lastname: Hasnain
authors.forename: Victor M
authors.initials: VM
authors.lastname: Goldberg
authors.forename: Tariq M
authors.initials: TM
authors.lastname: Haqqi
mesh_terms: D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000201:enzymology; D017364:Collagenases / Q000378:metabolism*; D003497:Cyclic N-Oxides; D004789:Enzyme Activation; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D053509:Matrix Metalloproteinase 13; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology; D009589:Nitrogen Oxides / Q000494:pharmacology*; D010003:Osteoarthritis / Q000473:pathology; D018808:Transcription Factor AP-1 / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D003497:Cyclic N-Oxides; D007375:Interleukin-1; D018696:Neuroprotective Agents; D009589:Nitrogen Oxides; D018808:Transcription Factor AP-1; C029217:phenyl-N-tert-butylnitrone; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D017364:Collagenases; C507079:MMP13 protein, human; D053509:Matrix Metalloproteinase 13