Ethanol enhances the IFN-gamma, TGF-alpha and IL-6 secretion in psoriatic co-cultures

Evidence suggests an association between alcohol consumption and psoriasis. This relationship is still undefined, although long-term alcohol intake influences the immune system. Interactions between T cells and keratinocytes are important for the pathogenesis of psoriasis, by secretion of pro-inflammatory cytokines and growth factors in psoriatic skin. IL-2, IL-6, IL-8, IFN-gamma and TGF-alpha are hallmark cytokines in a psoriatic cytokine network. We investigated whether ethanol influences the secretion of these cytokines using a co-culture model with keratinocytes from psoriatic patients (n = 9) or from healthy controls (n = 9), with HUT 78 lymphocytes, and determined the cytokine levels with or without ethanol treatment in the culture supernatants. TGF-alpha and IFN-gamma levels were elevated in the ethanol-treated psoriatic co-cultures, to 150% and 175% respectively, but neither in co-cultures with keratinocytes derived from healthy control individuals nor in monocultures. Treatment with ethanol elevated slightly the IL-6 levels in the monocultures from psoriatic and control keratinocytes to 125% but not in HUT 78 monocultures. In the psoriatic co-cultures, IL-6 levels were elevated in the culture supernatants to almost 160%, but they were not influenced by ethanol in co-cultures with control keratinocytes. The cytokine levels of IL-8 or IL-2 were not significantly influenced in the psoriatic mono- and co-cultures or in HUT 78 cultures. If ethanol influences the cytokine secretion of psoriatic keratinocytes and HUT 78 lymphocytes in co-culture conditions, these data suggest that ethanol could also influence the psoriatic cytokine network in vivo, which may explain the explain the aggravation of this disease in alcohol-consuming psoriatic patients.