Thermal Water from Uriage-les-Bains Exerts DNA Protection, Induction of Catalase Activity and Claudin-6 Expression on UV Irradiated Human Skin in Addition to Its Own Antioxidant Properties

Abstract

Aim : In order to decipher the mechanisms underlying the known protective effects of the thermal water from Uriage-les-Bains (TWFULB) on the skin barrier function, we studied its antioxidant properties as well as its effect on the expression of the tight-junctional protein claudin-6, a candidate tumor suppressor factor. Study Design/Methods : In a first step, TBARS and SOD activity assays were performed in an in vitro model of human dermal fibroblasts treated by hypoxanthine/xanthine oxidase (HO/XO) mixture, in order to evaluate the own antioxidant effect of the thermal water. In a second step, human keratinocytes irradiated or not by UVB were used to evaluate the protective role of TWFULB on nuclear DNA damage using a comet assay. In a third step, an ex vivo model of human skin explants irradiated or not by UVA and UVB was used to evaluate the effect of TWFULB on the intracellular catalase activity and on the cutaneous claudin-6 expression. Results : TWFULB showed significant protective effects against oxidative stress induced by HO/XO: the cell viability was improved and the lipid peroxidation was reduced. The tested thermal water also showed significant SOD-like activity and protective effect on the UVB-stressed DNA. Considering the ex vivo models of skin explants, TWFULB was able to counterbalance the “negative” effect of UVB on the intracellular catalase activity and on the cutaneous claudin-6 expression. Conclusion : This multiparametric approach shows the antioxidant activity of TWFULB and emphasizes its role in the DNA protection of the cutaneous tissue in front of the UV irradiations, and finally suggests that some effects could involve the candidate suppressor functions of claudin-6.