The effects of BW755C and other anti-inflammatory drugs on eicosanoid concentrations and leukocyte accumulation in experimentally-induced acute inflammation

Abstract

BW755C (3-amino-1-[m-trifluoromethyl)phenyl]-2-pyrazoline HCl) reduced the concentration of leukotriene B4 (LTB4), thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) in exudate derived from the subcutaneous implantation in rats of 0.5% carrageenan-impregnated polyester sponges. Polymorphonuclear leukocyte (PMN) migration into the inflammatory exudate was also decreased. The inhibition of LTB4 may, in part, account for the lower number of cells in the exudate since LTB4 is a potent leukotactic agent. Inhibition of LTB4-formation and cell migration by BW755C was dose-related, but the two dose-response curves were not parallel. Cell influx still occurred at doses of BW755C that completely inhibited formation of LTB4: this indicates that, although LTB4 may have a chemotactic role in-vivo, other factors must also contribute to cell migration into the inflammatory exudate. Treatment of rats with dexamethasone also caused a reduction in leukocytes and eicosanoids in the exudate. As with BW755C, there was a differential effect on PMN and LTB4: dexamethasone (1 mg kg-1) reduced PMN accumulation by 40% but LTB4 formation was inhibited by 70%. Leukocyte accumulation was also inhibited by the non-steroidal anti-inflammatory drugs (NSAID's), indomethacin and flurbiprofen. These drugs reduced the concentration of both PGE2 and TXB2 in exudate but that of LTB4 was unchanged. This suggests that reduction of PMN accumulation by indomethacin and flurbiprofen is mediated by a mechanism other than inhibition of LTB4-synthesis. Aspirin also reduced the levels of PGE2 and TXB2 in the exudate but did not consistently affect PMN influx, thereby confirming that inhibition of cyclo-oxygenase does not reduce cell migration in inflammation.