Robert, C., O. Doucet, M. Bonnet, B. Bertino and L. Zastrow.� Assessment of P53, P21 Protein Expression and Cyclobutane Pyrimidine Dimer Formation in a Human Skin Culture Model Following Acute UVB-Exposure. ATLA� 27:� 304.� 1999.

 

The aim of this study was to investigate, in vitro, by using a commercialized human skin culture model, the interest of new endpoints, which have recently been described as relevant markers of UV-induced damage, in vivo, in human skin.� Reconstituted epidermis (Rep) was exposed to a subtoxic dose of UVB.� The UV-induced damaging effects were regularly investigated over 72 hours through examination of cell regulatory mechanisms (p53 and p21 protein expression) and DNA damage (cyclobutane pyrimidine dimer [CPD] formation).� The time-course response of these events was compared to the occurrence of inflammatory phenomena investigated through quantification of mRNA expression (RT-PCR) of cytokines (IL-1a, IL-6, IL-8, TNFa) and measurement of their respective intracellular and extracellular concentrations.� Under the experimental conditions, we observed that, during the first 6 hours following UV exposure, the cell viability of the Rep model was only slightly impaired.� In contrast, a clear increase in the number of CPDs was observed in the nuclei of the irradiated cells.� Similarly, within this period of time, the number of p53-positive cells and, to a lesser extent, the number of p21-positive cells, were increased in the basal and suprabasal layers of the UV-exposed skin cultures.� These results were consistent with the presence of inflammatory phenomena occurring, since the intracellular and extracellular concentrations of IL-1a, IL-6, IL-8 and TNFa showed a striking increase.� These results suggest that p53 and p21 protein expression, and CPD formation, could be used to assess acute UVB-induced skin damage in this commercialized skin culture model.�