Blue light induces DNA damage in normal human skin keratinocytes.

Background: The generation of DNA damage by ultra-violet radiations (UV) is well established, and both the nature of the DNA lesions and their respective DNA repair pathways have largely been described. Besides UV rays, visible light constitutes a very important part of the sun spectrum where blue light is considered a significant contributor to premature aging. However, blue light-induced DNA damage has not been deeply explored yet.

Methods: In the present study, we assessed in human skin keratinocytes the DNA and chromosome damaging activities of blue light rays (415 nm) as well as their associated DNA repair mechanisms.

Results: Our results demonstrated that blue light induced dose-dependent DNA damage in human keratinocytes. Both oxidative and cyclobutane-pyrimidine-dimer (CPD) DNA lesions were generated. They were repaired through base excision repair (BER) and nucleotide excision repair (NER) pathways, respectively. Moreover, by using the micronucleus assay we demonstrated, for the first time, that a blue wavelength exerted a clastogenic/aneugenic effect in human keratinocytes, leading to chromosome aberration.

Conclusion: We concluded that, in normal human keratinocytes, blue light creates genotoxic lesions which might accelerate or at least contribute to premature skin aging.