Differential effects of inhibition of isoforms of cyclooxygenase (COX-1, COX-2) in chronic inflammation.
OBJECTIVE
The anti-inflammatory effects of therapeutic dosing of drugs with greater selectivity for the inhibition of the constitutive (COX-1) or inducible isoform (COX-2) of cyclooxygenase were assessed in a model of chronic inflammation.


METHODS
The murine chronic granulomatous tissue air pouch model involves the subcutaneous injection of air into the dorsum of mice followed 24 h later by the intrapouch injection of an inflammatory stimulus (0.5 ml of Freund's complete adjuvant containing 0.1% croton oil). Aspirin, more selective in vitro for the inhibition of COX-1 (10,200 (mg/kg) and nimesulide, a selective in vitro inhibitor of COX-2 (0.5, 5 mg/kg) were dosed p.o. daily from 3 days after injection of the inflammatory stimulus. Granuloma dry weight, vascularity and COX activity (measured as PGE2) were assessed at various time points throughout the inflammatory lesion to resolution at day 28. A second COX-2 inhibitor, NS 398 (0.1, 1, 10 mg/kg), was dosed p.o. daily from 3 days after the injection of the inflammatory stimulus and its effects on granuloma dry weight, vascularity and COX activity were measured at 7 days.


RESULTS
Aspirin (200 mg/kg) significantly inhibited levels of PGE2 throughout the time course and at the lower dose (10 mg/kg) from day 14. Nimesulide (5 mg/kg) however, significantly increased levels of PGE2 at days 5 and 21, but at 0.5 mg/kg was without effect. Aspirin (200 mg/kg) significantly reduced granuloma dry weight at day 14 but had no effect on granuloma vascularity at day 7. In contrast, nimesulide (5 mg/kg) significantly increased granuloma vascularity at day 7 and granuloma dry weight at day 14. NS-398 at all doses had no effect on granuloma dry weight, vascularity or COX activity 7 days after the injection of the inflammatory stimulus.


CONCLUSIONS
In this model of chronic inflammation, aspirin, more selective for the inhibition of COX-1 is more effective than the selective COX-2 inhibitors nimesulide and NS-398 at inhibiting granuloma dry weight, vascularity and COX activity.
Gilroy
D W
DW
Department of Experimental Pathology, St. Bartholomew's and the Royal London School of Medicine and Dentistry, UK.
Tomlinson
A
A
Willoughby
D A
DA
D000388:Air; D000400:Air Sacs; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D003436:Croton Oil; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000627:therapeutic use*; D004195:Disease Models, Animal; D004790:Enzyme Induction / Q000187:drug effects; D005620:Freund's Adjuvant; D006099:Granuloma / Q000139:chemically induced / Q000188:drug therapy; D007527:Isoenzymes / Q000096:biosynthesis*; D008565:Membrane Proteins; D051379:Mice; D009578:Nitrobenzenes / Q000627:therapeutic use*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis; D013449:Sulfonamides / Q000627:therapeutic use*
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; D003436:Croton Oil; D005620:Freund's Adjuvant; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496512:Ptgs1 protein, mouse; D001241:Aspirin; C012655:nimesulide