Dehydroxymethylepoxyquinomicin, a novel nuclear factor-kappaB inhibitor, prevents inflammatory injury induced by interferon-gamma and histamine in NCTC 2544 keratinocytes.

1. The novel nuclear factor (NF)-kappaB inhibitor dehydroxymethylepoxyquinomicin (DHMEQ) is a derivative of the antibiotic epoxyquinomicin C from Amycolatopsis sp. that has been found to inhibit tumour necrosis factor (TNF)-alpha-induced activation of NF-kappaB by suppressing nuclear translocation of NF-kappaB. The aim of the present study was to determine the effects of DHMEQ on interferon (IFN)-gamma- and histamine-activated NCTC 2544 keratinocytes. 2. Keratinocytes were stimulated or not with 200 U/mL IFN-gamma and 10(-4) mol/L histamine in the absence or presence of different concentrations of DHMEQ (1, 5 and 10 microg/mL) or hydrocortisone (10(-5) mol/L), which was used as a reference anti-inflammatory drug. After 48 h, each sample was tested for the presence of intercellular adhesion molecule (ICAM)-1 by western blot analysis, as well as for the release of monocyte chemoattractant protein (MCP)-1, RANTES and interleukin (IL)-8 using specific sandwich ELISAs. To verify the effect of DHMEQ on cell viability of non-stimulated NCTC 2544 keratinocytes, the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was used. 3. The results showed that 10 microg/mL DHMEQ potently inhibited ICAM-1 production (by 50%), as well as the release of MCP-1 (to 25% of control), RANTES (to 5% of control) and IL-8 (to 2% of control). The results of the MTT assay indicated that DHMEQ has no effect on cell viability. 4. In conclusion, DHMEQ inhibits the IFN-gamma- and histamine-induced activation of the keratinocyte cell line NCTC 2544. The anti-inflammatory effects of DHMEQ could be exploited by applying the drug topically alone or in combination with sub-toxic concentrations of anti-inflammatory drugs to producer a synergistic effect.