Proteomic analysis identifies new biomarkers for postmenopausal and dry skin.

A proteomic analysis of stratum corneum (SC) samples of normal healthy skin revealed the presence of more than 70 proteins by 2D electrophoresis. The majority of these proteins to our knowledge have not yet been described in normal SC. We analysed by Western blot the levels of 25 proteins in the SC taken from postmenopausal and dry skin compared with young and normal skin, respectively. In postmenopausal skin, there was a significantly increased amount of heat shock protein 27, plakoglobin and desmoglein 1, whereas transglutaminase 3, apolipoprotein D and acid ceramidase levels were significantly reduced compared with the SC of young skin. We confirmed corneodesmosin as a marker of dry skin. In addition, we showed for the first time that the levels of both phosphatidylethanolamine-binding protein 1 and annexin A2 were significantly increased in the SC of dry skin compared with the SC of normal skin. These results suggest that a proteomic analysis of the SC obtained using a non-invasive varnish stripping method is an attractive alternative to invasive methods to better characterize changes in the physiology of ageing and dry skin.

The EpiSkin phototoxicity assay (EPA): development of an in vitro tiered strategy using 17 reference chemicals to predict phototoxic potency.

The aim of the study was to investigate the ability of human reconstructed epidermis EpiSkin(LM) to identify the phototoxic potency of topically or systemically applied chemicals (EPA: EpiSkin phototoxicity assay). Three classes, according to their available human phototoxic potential, were evaluated: systemic phototoxic compounds, topical phototoxic chemicals and non-phototoxic compounds. Non-cytotoxic concentrations of chemicals were applied topically or directly added to the underlying culture medium in order to mimic a systemic-like administration. Following treatment, tissues were exposed to non-cytotoxic dose of UVA (50 J cm(-2)). Cell viability and pro-inflammatory mediators (IL-1alpha) were investigated 22 h after UVA exposure. Our results show that the phototoxic potential of chemicals can be determined using cell viability combined with inflammatory mediator measurements (cytokine IL-1alpha) in a 3-D epidermis model. Moreover, the EPA was able to discriminate efficiently between phototoxic and non-phototoxic products. Furthermore, the EPA is sensitive to the administration route in the prediction of the phototoxic potency of the tested chemical. Differences observed between the two routes of administration (topical or systemic-like) may be linked in part to chemicals bioavailability which depends on specific penetration potential, epidermis barrier function and also on keratinocytes absorption/metabolization processes. Results were very promising and showed a very good sensitivity (92.3%) and an excellent specificity (100%) with an overall accuracy of 94.1%. The performances of the EPA showed that the EpiSkin(LM) model is an interesting tool able to integrate decision-making processes to address the question of phototoxicity linked to the application site.