Activation of macrophage peroxisome proliferator-activated receptor-γ by diclofenac results in the induction of cyclooxygenase-2 protein and the synthesis of anti-inflammatory cytokines

• Published in: Molecular and cellular biochemistry Vol. 327; no. 1-2; pp. 101 - 110
• Main Authors: Ayoub, Samir S., Botting, Regina M., Joshi, Amrish N., Seed, Michael P., Colville-Nash, Paul R.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.07.2009
• Subjects: Animals; Anti-Inflammatory Agents, Non-Steroidal - pharmacology; Biochemistry; Biomedical and Life Sciences; Cardiology; Cyclooxygenase 2 - genetics; Cyclooxygenase 2 - metabolism; Cytokines - biosynthesis; Diclofenac - pharmacology; Dose-Response Relationship, Drug; Inflammation - metabolism; Life Sciences; Lipopolysaccharides - metabolism; Lipopolysaccharides - pharmacology; Macrophages - drug effects; Macrophages - enzymology; Macrophages - immunology; Medical Biochemistry; Mice; Mice, Inbred BALB C; Oncology; PPAR gamma - metabolism; Rats; Rats, Wistar; Transcription Factors - metabolism; Lipopolysaccharide; J774.2; Paracetamol; Cyclooxygenase-2; Peroxisome proliferator-activated receptor-γ; Diclofenac
• ISSN: 0300-8177; 1573-4919
• DOI: 10.1007/s11010-009-0048-y

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 μM diclofenac. Pre-treatment of cells with the peroxisome proliferator-activated receptor-γ (PPAR-γ) antagonists GW9662 (0.1–1 μM) or biphenol A Diglycidyl Ether (100–200 μM) resulted in reduction of the induction of COX-2 by diclofenac, but not by LPS. Induction of COX-2 by the PPAR-γ agonist 15deoxyΔ 12,14 prostaglandin J 2 was also reduced when the cells were pre-treated with the PPAR-γ antagonists BADGE or GW9662. On the other hand, pre-treatment of cells with the nuclear factor-kappa-B (NF-κB) Super-repressor IκBα (150–600 nM) reduced the induction of COX-2 by LPS, but not by diclofenac. We, therefore, have identified that PPAR-γ 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-β suggest that the diclofenac-induced COX-2 protein may possess anti-inflammatory actions.