Blue light impairs the repair of UVB-induced pyrimidine dimers in a human skin model.

In recent years, interest is growing in the biological cutaneous effects of high-energy visible light (400-450 nm). In the present study, we explored the impact of blue light (BL) on the repair of pyrimidine dimers, the major class of premutagenic DNA damage induced by exposure to sunlight. We unambiguously demonstrate that the exposure of in vitro reconstructed human epidermis to environmentally relevant doses of BL strongly decreases the rate of repair of cyclobutane pyrimidine dimers and pyrimidine (6-4) pyrimidone photoproducts induced by a subsequent UVB irradiation. Using the highly sensitive and specific liquid chromatography-tandem mass spectrometry assay, we did not observe induction of pyrimidine dimers by BL alone. Finally, we showed that application, during the BL exposure step, of a formula containing a new filter, named TriAsorB and affording BL photoprotection, prevented the decrease in DNA repair efficiency. These results emphasize the potential deleterious effects of BL on DNA repair and the interest in providing adequate skin protection against this wavelength range of sunlight.