Anti-oxidant defence mechanism in vitiliginous skin increases with skin type

Background Vitiligo skin shows different burning capacity in people with different phototype. In normal skin antioxidant status is correlated to skin phototype, but unexpectedly it appears that there is a gradual decrease in burning susceptibility of depigmented skin of individuals with increasing phototype (IIVI). Objective To assess if the antioxidant response in the lesional vitiligo skin is involved in those protection mechanisms. Moreover, a possible correlation between cutaneous and systemic endogenous antioxidants in vitiligo patients has been investigated. Methods We enrolled in the study 29 patients with active vitiligo, divided into five groups according to skin type (II to VI). We analysed reduced and oxidized glutathione (GSH and GSSG, respectively), ubiquinone (CoQ10), catalase (Cat), superoxide dismutases (Cu/Zn-SOD and Mn-SOD), GSH peroxidase (GSH-Px), as indexes of chemical and enzymatic antioxidants, in suction blister roofs as well as in peripheral blood mononuclear cells (PBMNCs). Results The vitiligo patients showed an imbalance of antioxidant network, both in depigmented skin and PBMNCs. Interestingly, in vitiligo skin a phototype-related increase of antioxidant enzyme activities (Cat, Mn-SOD and GPx) and GSH amount have been observed. Similarly in PMBNCs Cat and total SOD activities, as well as GSH content progressively increased from skin type II to skin type VI. Endogenous antioxidants in vitiligo skin are correlated to those in PBMNCs, suggesting that systemic and epidermal antioxidant network functionalities are connected. Conclusions The correlation between antioxidant levels and clinical phototype confirmed the hypothesis that other factors than melanin determine largely the minimal erythema dose values in vitiligo lesional skin.