082 Effect of blue light overexposure on normal human keratinocytes and ex vivo skin, in vivo objectivation

In the visible spectrum, blue light (400-495 nm) represents the High Energy Visible (HEV) light associated with high photon energy. The majority of blue light comes from the sun, but it appears that we are more and more exposed to artificial light sources, including light-emitting electronic devices that emit significant amounts of blue light. Recently, opsin receptor expression has been reported in human epidermal cells, with three of them being sensitive to blue light. The role of blue light overexposure on the physiological skin condition has been poorly described. The aim of the present study was to evaluate the effect of blue light exposure on Normal Human Keratinocytes (NHK) using LED irradiation. Exposure conditions generating Reactive Oxygen Species (ROS) accumulation were first determined in NHKs. In these conditions, the levels of opsins OPN1 SW, OPN2 and OPN3 were observed to have decreased at specific wavelengths of blue LED. We also treated NHKs with a peptidic extract of Cocoa porcelana and observed a partial preservation of keratinocyte photoreceptors after blue LED exposure. Moreover, ex vivo studies on skin biopsies showed the effects of blue LED overexposure on the elastic fiber network and its preservation associated with the application of the extract. To evaluate the positive effect of a peptidic extract of Cocoa porcelana on the visible signs of aging linked to prolonged exposure to blue light, an in vivo study was performed on the faces of 20 volunteers. At the end of the treatment, wrinkle parameters were observed to have decreased significantly on the treated side compared to the placebo side. Taken together, our results showed that the expression of opsin receptors could be disrupted by blue LED overexposure in NHKs, associated with an oxidative stress response. Moreover, the in vivo study showed an association with an observed decrease in wrinkle appearance. These studies represent a new approach regarding skin sensitivity to blue light through opsin receptors.