It is now recognized that both ultraviolet (UV)-A and UVB wavelengths participate in the generation of photodamaged human skin during sun exposure. During usual daily activities, an appropriate protection against solar UV exposure should prevent clinical, cellular, and molecular changes potentially leading to photoaging.
This study was designed to evaluate in human beings the protection afforded by a day cream containing a photostable combination of UVB and UVA filters and thus protect against the UV-induced skin alterations.
In solar-simulated radiation exposed and unprotected skin sites we observed melanization. The epidermis revealed a significant increase in stratum corneum and stratum granulosum thickness. In the dermis, an enhanced expression of tenascin and a reduced expression of type I procollagen were evidenced just below the dermoepidermal junction. Although no change in elastic fibers in exposed buttock skin was seen, a slightly increased deposit of lysozyme and alpha-1 antitrypsin on elastin fibers was observed using immunofluorescence techniques. A day cream with photoprotection properties was shown to prevent all of the above-described alterations.
This study was performed on a limited number of patients (n = 12) with specific characteristics (20-35 years old and skin type II and III). Two dermal alterations were evaluated by visual assessment and not by computer-assisted image analysis quantification.
Our in vivo results demonstrate the benefits of daily photoprotection using a day cream containing appropriate broad-spectrum sunscreens, which prevent solar UV-induced skin damages.