Increased carbonyl protein level in the stratum corneum of inflammatory skin disorders: A non-invasive approach.

The stratum corneum (SC) is the interface of body and environment, and is continuously exposed to oxidative stress, resulting in carbonyl modification of proteins. We have developed a simple and non-invasive method to assess carbonyl protein (CP) level in the SC, applied it to various kinds of skin, and revealed a link between the stratum corneum carbonylated protein (SCCP) level and water content in the SC. The purpose of the present study is to examine the SCCP level in inflammatory skin disorders associated with xerosis. Psoriasis vulgaris (PV) and atopic dermatitis (AD) are typical inflammatory skin disorders, of which the stratum corneum shows markedly low water content. SC samples were non-invasively collected from the lesional and non-lesional areas of PV and AD by adhesive tape stripping, and their carbonyl groups were determined by reaction with fluorescein-5-thiosemicarbazide. The average fluorescence intensity of the SC was calculated as SCCP level. Higher SCCP level was observed in the lesional area of PV as compared with non-lesional area or healthy control. Lesional area of AD also exhibited higher SCCP level than corresponding non-lesional area, of which SCCP level was slightly higher than the healthy control. These data suggest the involvement of oxidative modification of the SC protein, at least in part, in generation of xerotic skin in inflammatory skin disorders as well as dry skin in healthy subjects.