Diarylheptanoid hirsutenone prevents tumor necrosis factor-alpha-stimulated production of inflammatory mediators in human keratinocytes through NF-kappaB inhibition.

Keratinocytes may play an important role in the pathogenesis of skin disease in atopic dermatitis. Diarylheptanoids such as oregonin and hirstanonol are demonstrated to have anti-inflammatory and anti-oxidant effects. The present study was to investigate the effect of hirsutenone, one of the diarylheptanoids, against tumor necrosis factor (TNF)-alpha-stimulated responses in human keratinocytes. Hirsutenone attenuated the TNF-alpha-induced production of cytokine IL-8, prostaglandin E(2) and chemokine CCL27, and the formation of reactive oxygen/nitrogen species in keratinocytes. Immunosuppressants (dexamethasone and cyclosporin A) inhibited the TNF-alpha-elicited formation of IL-8, prostaglandin E(2) and CCL27, but did not affect formation of reactive species. Bay 11-7085 (an inhibitor of NF-kappaB activation) and anti-oxidant N-acetylcysteine attenuated the TNF-alpha-induced formation of inflammatory mediators and reactive species. Hirsutenone, dexamethasone, cyclosporin A and Bay 11-7085 inhibited the TNF-alpha-induced phosphorylation of inhibitory kappaB and the activation of nuclear factor (NF)-kappaB. The results show that hirsutenone seems to reduce the TNF-alpha-stimulated production of inflammatory mediators in keratinocytes by suppressing the activation of NF-kappaB that may be mediated by reactive oxygen species. The findings suggest that hirsutenone may exert an inhibitory effect against the pro-inflammatory mediator-induced skin disease.