Increased cysteinyldopa plasma levels hint to melanocyte as stress sensor in psoriasis.

The possible role of melanocyte as a modulator of the inflammation and keratinocyte hyperproliferation in psoriasis has been hypothesised but never demonstrated on experimental basis. Aim of the present study was to assess whether plasma levels of 5-S-cysteinyldopa (CD), a metabolite reflecting melanocyte activity, undergo changes in association with psoriasis together with those of typical lipid peroxidation markers thiobarbituric acid reactive substances (TBARS). A group of 16 patients with psoriasis at different stage as indicated by the psoriasis area and severity index (PASI) were enrolled against an age and sex matched control group. Both TBARS (P<0.05) and CD (P<0.005) levels were higher than controls with statistical significance. After 1 month therapy the levels of either biomarkers decreased with respect to the starting values although with marked individual differences. CD may represent a novel and sensitive biomarker for the follow up of psoriasis and evaluation of the efficacy of therapeutic regimens beyond PASI determination.