sq-23377 and tepoxalin

Tepoxalin, a dual inhibitor of cyclooxygenase (CO) and 5-lipoxygenase (5LO) with cytokine modifying activity, is also a potent inhibitor of the transcription factor, nuclear factor kappa B (NF kappa B). NF kappa B is a pleiotropic activator that is involved in the regulation of many genes whose products participate in immune or inflammatory responses. Tepoxalin inhibited in a dose related manner NF kappa B activation by PMA + ionomycin or H2O2 in Jurkat and HeLa cells. TNF-alpha-induced NF kappa B was also inhibited by tepoxalin in HeLa cells, while relatively less marked inhibition was observed in Jurkat cells. Activation of NF kappa B in several monocytic cell lines was also suppressed by tepoxalin. However AP-1 stimulation under the same conditions was not affected by tepoxalin. Other CO, LO inhibitors such as naproxen or zileuton did not inhibit NF kappa B activities. This inhibitory activity of tepoxalin was further illustrated by its suppression of NF kappa B regulated genes such as IL-6 in PMA stimulated human PBL and c-myc in IL-2 dependent T cell lines. Tepoxalin also blocked PMA + ionomycin-induced I kappa B degradation in a time-dependent fashion. The possible mechanism of tepoxalin in NF kappa B activation and its potential clinical application are discussed.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Base Sequence; Cell Line; Chloramphenicol O-Acetyltransferase; Cyclooxygenase Inhibitors; DNA Primers; Gene Expression; HeLa Cells; Humans; Hydroxyurea; Interleukin-6; Ionomycin; Kinetics; Lipoxygenase Inhibitors; Mice; Molecular Sequence Data; Naproxen; NF-kappa B; Oligodeoxyribonucleotides; Polymerase Chain Reaction; Proto-Oncogene Proteins c-myc; Pyrazoles; Recombinant Proteins; Tetradecanoylphorbol Acetate; Transfection; Tumor Cells, Cultured

Tepoxalin, a compound previously identified as a dual cyclooxygenase/lipoxygenase (CO/LO) inhibitor, is a potent inhibitor of T cell proliferation. Comparing the suppressive effects of tepoxalin and cyclosporin A (CsA) on OKT3-, PMA-, IL-2-, and PMA+ionomycin-induced T cell proliferations revealed marked differences in the mechanism of action between the two compounds. Whereas CsA was most effective in suppressing OKT3-stimulated proliferation, tepoxalin was more potent in inhibiting PMA-, PMA+ionomycin-, and IL-2-induced proliferation. Quantitative PCR (QPCR) assays used to detect cytokine messages showed that tepoxalin blocked IL-2 mRNA transcription in PMA- and PMA+ionomycin-, but not OKT3-stimulated T cells whereas CsA was most potent in inhibiting OKT3-induced IL-2 mRNA induction in these cells. Both tepoxalin and CsA did not inhibit the expression of IL-2R; however, only tepoxalin, but not CsA, inhibited the proliferation of IL-2-dependent blasts and the transcription of IFN-gamma, an IL-2-dependent target gene. Moreover, addition of exogenous IL-2 restored OKT3-induced proliferation to CsA- but not tepoxalin-treated cells. These data suggest that tepoxalin, but not CsA, suppressed T cell proliferation by inhibiting IL-2-induced signal transduction. Consistent with these findings, tepoxalin, unlike CsA, which was most potent when added at the initiation of OKT3 stimulation, was equally active, regardless of whether it was added at the beginning or 48 h after culture initiation. The difference in mechanism of action between tepoxalin and CsA was confirmed further by the synergistic suppressive effects on T cell proliferation upon co-administration of the two compounds.

Topics: Base Sequence; Cell Line; Cyclosporine; Humans; Immunosuppressive Agents; Interleukin-2; Ionomycin; Lymphocyte Activation; Molecular Sequence Data; Muromonab-CD3; Polymerase Chain Reaction; Pyrazoles; Receptors, Interleukin-2; RNA, Messenger; Signal Transduction; Tetradecanoylphorbol Acetate