[Kinetics of lipid peroxidation induced by UV beta rays in human keratinocyte and fibroblast cultures]

Lipid peroxidation has been implicated in skin damage by ultraviolet radiation. The aim of the study was to determine the kinetic of lipid peroxidation induced by ultraviolet beta (UVB) in adult keratinocytes and fibroblasts in culture. The keratinocytes were obtained from a single primary culture and the fibroblasts were in the same subculture (4 to 10 transfers). For UVB irradiation, the cells were maintained in a small volume of Hanks balanced salt solution and were irradiated (0.75, 1.5, 3 and 4.5 Jcm-2). Then cells were cultured for 3 to 48 hours. Lipid peroxidation was estimated by free MDA determination in both extracellular medium and cells using a size exclusion chromatography coupled to an HPLC procedure. In addition, LDH release in culture media was evaluated as in indice of cytotoxicity. An increase of total free MDA was observed 3 hours after cell irradiation which was dose-dependent from 0.75 to 3 Jcm-2 for keratinocytes and fibroblasts. MDA was detected both in cells and in culture media. As soon as 3 hours after irradiation 90% in total MDA was present in the culture media. Kinetic of lipid peroxidation: for 0.75 Jcm-2, an elevation of MDA was observed 12 hours after irradiation in both cultures. A further increase in MDA was noted 24 hours after fibroblasts irradiation but not in irradiated keratinocytes. LDH release in culture media increased with post irradiation time until 48 hours. The cytotoxic effect of UVB irradiation on keratinocytes and fibroblasts cultures was shown by an enhancement of lipid peroxidation which was detectable during 48 hours after irradiation. An increase of LDH release was observed simultaneously.