Permeability barrier abnormality of hairless mouse epidermis after topical corticosteroid: characterization of stratum corneum lipids by ruthenium tetroxide staining and high-performance thin-layer chromatography.

Topical corticosteroids (TCS) are among the most frequently used topical therapeutics. Recently, it has been shown that TCS not only has antiproliferative actions, but also inhibits the differentiation of the epidermis and finally perturbates stratum corneum (s.c.) barrier function. It is well established that epidermal barrier function resides within the intercellular lipids of the SC. However, to date, little is known about the effects of TCS on the structure and composition of s.c. lipids. We therefore used hairless mouse skin to study the sequential changes of the s.c. permeability barrier and their intercellular lipids by ruthenium tetroxide staining and high-performance thin-layer chromatography (HPTLC) during topical use of corticosteroids. The results demonstrated a progressive increase in transepidermal water loss accompanied by a diminution in the SC intercellular lipid lamellae, which showed a normal structure of individual lamella. Analysis of lipid composition by HPTLC after a 6-week application of TCS also showed an obvious decrease in all the main components of s.c. lipids, which are known to constitute the permeability barrier of the skin. In light of these results, our work provides direct morphological evidence that TCS deteriorates the permeability barrier of epidermis when applied to normal skin.