Activation of macrophage peroxisome proliferator-activated receptor-gamma by diclofenac results in the induction of cyclooxygenase-2 protein and the synthesis of anti-inflammatory cytokines.
Cyclooxygenase-2 (COX-2) is an inducible isoform of the COX family of enzymes central to the synthesis of pro-inflammatory prostaglandins. Induction of COX-2 is mediated by many endogenous and exogenous molecules that include pro-inflammatory cytokines and bacterial lipopolysaccharide (LPS). It has been demonstrated that COX-2 can also be induced by diclofenac in cultured J774.2 macrophages. This induction was delayed compared to COX-2 induced by LPS and paracetamol selectively inhibited activity of this protein. The aim of the present study was to determine the transcription factor involved in the production of COX-2 after treatment of J774.2 cells with 500 microM diclofenac. Pre-treatment of cells with the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) antagonists GW9662 (0.1-1 microM) or biphenol A Diglycidyl Ether (100-200 microM) resulted in reduction of the induction of COX-2 by diclofenac, but not by LPS. Induction of COX-2 by the PPAR-gamma agonist 15deoxyDelta(12,14)prostaglandin J(2) was also reduced when the cells were pre-treated with the PPAR-gamma antagonists BADGE or GW9662. On the other hand, pre-treatment of cells with the nuclear factor-kappa-B (NF-kappaB) Super-repressor IkappaBalpha (150-600 nM) reduced the induction of COX-2 by LPS, but not by diclofenac. We, therefore, have identified that PPAR-gamma activation is a requirement for COX-2 induction after diclofenac stimulation of J774.2 cells. These results along with the finding that treatment of J774.2 macrophages with diclofenac resulted in the release of the anti-inflammatory cytokines, interleukin-10 and transforming growth factor-beta suggest that the diclofenac-induced COX-2 protein may possess anti-inflammatory actions.
Ayoub
Samir S
SS
Centre for Biochemical Pharmacology, William Harvey Research Institute, Bart's and the Royal London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK. s.s.ayoub@qmul.ac.uk
Botting
Regina M
RM
Joshi
Amrish N
AN
Seed
Michael P
MP
Colville-Nash
Paul R
PR
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D016207:Cytokines / Q000096:biosynthesis*; D004008:Diclofenac / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007249:Inflammation / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D047495:PPAR gamma / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D014157:Transcription Factors / Q000378:metabolism
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016207:Cytokines; D008070:Lipopolysaccharides; D047495:PPAR gamma; D014157:Transcription Factors; D004008:Diclofenac; D051546:Cyclooxygenase 2