Stratum corneum
lipids are an important determinant for both water-retention function and permeability-barrier function in the stratum corneum. However, their major constituent,
ceramides, have not been analyzed in detail in
skin diseases such as
atopic dermatitis that show defective water-retention and permeability-barrier function. In an attempt to assess the quantity of
ceramides per unit mass of the stratum corneum in
atopic dermatitis, stratum corneum sheet was removed from the forearm skin by stripping with
cyanoacrylate resin and placed in
hexane/
ethanol extraction to yield stratum corneum
lipids. The stratum corneum was dispersed by solubilization of
cyanoacrylate resin with
dimethylformamide, and after membrane filtration, the weight of the stratum corneum mass was measured. The
ceramides were quantified by thin-layer chromatography and evaluated as microgram/mg stratum corneum. In the forearm skin of healthy individuals (n = 65), the total
ceramide content significantly declined with increasing age. In
atopic dermatitis (n = 32-35), there was a marked reduction in the amount of
ceramides in the lesional forearm skin compared with those of healthy individuals of the same age. Interestingly, the non-lesional skin also exhibited a similar and significant decrease of
ceramides. Among six
ceramide fractions,
ceramide 1 was most significantly reduced in both lesional and non-lesional skin. These findings suggest that an insufficiency of
ceramides in the stratum corneum is an etiologic factor in atopic dry skin.