and The Miami Valley Laboratorieso, Procter and Gamble Co., Cincinnati Transcription, translation and secretion of interleukin 1 and tumor necrosis factor: effects of tebufelone, a dual cyclooxygenase/5-lipoxygenase inhibitor*
We examined the effect of tebufelone, a dual cyclooxygenase (CO)/5-lipoxygenase (LO) inhibitor, on the synthesis, secretion and gene expression of interleukin (IL) 1p and tumor necrosis factor (TNF)-a by human peripheral blood mononuclear cells (PBMC). Basal concentrations of immunoreactive IL l p and TNF-a after 18-24 h, in the absence or presence of tebufelone ( I 12.5 pM),were near the limit of detection (100 pg/ml). By contrast, preincubation (1 h) of cells, in amounts of tebufelone which decrease the formation of leukotriene (LT) Bq, markedly enhanced (up to 500%) the synthesis of IL l p and TNF-a following lipopolysaccharide (LPS), heat-killed Staphylococcus epidermidis or concanavalin A stimulation. Moreover, a disproportionate amount of the overall increase in I L l ( a and p) was secreted in contrast to the amount which remained cell associated, an effect unrelated to cell damage or leakage as tebufelone had no effect on either lactate dehydrogenase release by PBMC, or mitochondria1 dehydrogenases of adherent monocytes as detected by enzymatic cleavage of the substrate 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide. There was no inverse correlation between the changes in prostaglandin (PG)E2 levels and TNF-a or IL l p synthesis, and when PG formation was maximally inhibited by preincubating the cells in indomethacin, tebufelone, added 1 h before the stimulus, continued to enhance the synthesis of IL l p although not that of TNF-a.
The addition of the C0/5-L0 inhibitor 2 h after LPS stimulation, however, did not interfere with IL 1p synthesis, suggesting that tebufelone interacts with an early event(s) in the activation of PBMC. For ILlp and TNF-a, basal and stimulated (4 hpost LPS) mRNAlevels were not increased by tebufelone, despite a concomitant increase in the synthesis of ILlp. In conclusion, we have demonstrated that tebufelone enhances IL l ( a and p) and TNF-a synthesis at concentrations which suppress leukotriene formation. These findings argue against a role of 5-LO products as necessary intermediates of IL l(a and p) and TNF-a synthesis.