Differential Responses of Skin Keratinocytes and Fibroblasts to UVA-mediated Damage

Ultraviolet A(UVA,320 ～400 nm) irradiation generates significant oxidative stress,leading to deleterious effects in human skin: erythema,pigmentation,photosensitivity,photoaging and skin cancer.Epidermal keratinocytes and dermal fibroblasts are known to have different responses to UVA irradiation.Compared to fibroblasts,keratinocytes appear to be far more resistant to UVA-mediated oxidative damage,and differ in the other responses.Here we review the most recent findings that elaborate the differences in UVA-mediated response in these two cell types,including cell morphology,membrane damage,heme oxygenase(HO) activity and HO-1 inducibility,levels of harmful ‘free’ labile iron and other antioxidants.These experimental evidences may provide new clues for improvement of therapy against UVA-induced skin damage and for development of novel sunscreens.