title: Inducible cyclooxygenase may have anti-inflammatory properties.
abstract: Cyclooxygenase (COX) has two isoforms. Generally, COX 1 is constitutively expressed in most tissues, where it maintains physiological processes; inducible COX 2 is considered a pro-inflammatory enzyme and a chief target for the treatment of inflammatory diseases. Here we present evidence that COX 2 may have anti-inflammatory properties. In carrageenin-induced pleurisy in rats, the predominant cells at 2 hours are polymorphonuclear leucocytes, whereas mononuclear cells dominate from 24 hours until resolution at 48 hours. In this model, COX 2 protein expression peaked initially at 2 hours, associated with maximal prostaglandin E2 synthesis. However, at 48 hours there was a second increase in COX 2 expression, 350% greater than that at 2 hours. Paradoxically, this coincided with inflammatory resolution and was associated with minimal prostaglandin E2 synthesis. In contrast, levels of prostaglandin D2, and 15deoxy delta(12-14)prostaglandin J2 were high at 2 hours, decreased as inflammation increased, but were increased again at 48 hours. The selective COX 2 inhibitor NS-398 and the dual COX 1/COX 2 inhibitor indomethacin inhibited inflammation at 2 hours but significantly exacerbated inflammation at 48 hours. This exacerbation was associated with reduced exudate prostaglandin D2 and 15deoxy delta(12-14)prostaglandin J2 concentrations, and was reversed by replacement of these prostaglandins. Thus, COX 2 may be pro-inflammatory during the early phase of a carrageenin-induced pleurisy, dominated by polymorphonuclear leucocytes, but may aid resolution at the later, mononuclear cell-dominated phase by generating an alternative set of anti-inflammatory prostaglandins.
authors.affiliation: Department of Experimental Pathology, St. Bartholomew's & Royal London School of Medicine and Dentistry, UK.
authors.forename: D W
authors.initials: DW
authors.lastname: Gilroy
authors.forename: P R
authors.initials: PR
authors.lastname: Colville-Nash
authors.forename: D
authors.initials: D
authors.lastname: Willis
authors.forename: J
authors.initials: J
authors.lastname: Chivers
authors.forename: M J
authors.initials: MJ
authors.lastname: Paul-Clark
authors.forename: D A
authors.initials: DA
authors.lastname: Willoughby
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002351:Carrageenan / Q000633:toxicity; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D007213:Indomethacin / Q000494:pharmacology; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy / Q000378:metabolism; D007527:Isoenzymes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D009578:Nitrobenzenes / Q000494:pharmacology; D015230:Prostaglandin D2 / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: C097240:15-deoxy-delta(12,14)-prostaglandin J2; D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D009578:Nitrobenzenes; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D002351:Carrageenan; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat; D015232:Dinoprostone; D015230:Prostaglandin D2; D007213:Indomethacin