The use of a reconstructed epidermis in the assessment of cytotoxic effects of UV irradiation

Over the past years, different models have been proposed as alternatives to ocular and skin irritancy in animals. Among these models, skin and/or epidermis equivalents appeared to be promising. Cytotoxic effects of increasing doses of UVB, phototoxicity of different compounds following UVA irradiation (chlorpromazine, promethazine, rose bengal) and protective properties of a sunscreen emulsion containing increasing concentrations of an UVB filter (Mexoryl SO(TM)) were compared using either a reconstructed epidermis (Episkin(TM)) or human keratinocytes in monolayer culture. Endpoints included cell viability and Il-1alpha release. Results showed that the reconstructed epidermis react nearly like human epidermis in vivo which is known to absorb more than 50% of UVA and only 5 to 10% of UVB. As in the in vivo situation, cell toxicity as well as inflammatory mediators release induced by the phototoxic agents under investigation were largely increased following non cytotoxic doses of UVA. Finally, UVB irradiation (1 J/cm2) of Episkin(TM) pre-treated with an emulsion containing increasing concentrations of an UVB filter (Mexoryl SO(TM)), leads to a decrease in cell cytotoxicity as well as IL 1alpha release, up to a total protection.