Ceramides are the main polar lipids of the SC intercellular lipids; they play an important role in skin barrier function and account for half of the SC lipids by weight. Nine subclasses of ceramides have been described in human SC; these differ from each other by the sphingoid base groups (sphingosine, phytoshpingosine, 6-hydroxysphingosine) and hydrocarbon chain length. Ceramide content and changes of composition are involved in aging, and skin diseases such as atopic dermatitis (AD), psoriasis, contact dermatitis (CD) and irritant dermatitis.
Decreased ceramide levels: In several human skin diseases, diseased skin differs from healthy skin in the lipid composition of the SC’s intercellular matrix. Decreased levels of ceramides occur in atopic skin as compared with age-matched healthy controls. This data suggests that the decreased level of ceramides in the SC is a major pathophysiologic factor in these dry skin conditions; it is unclear whether this is a primary or secondary event.
Matsumoto et al. reported the difference in ceramide composition between dry skin (lesional) and normal skin (nonlesional) in AD. The weight of total ceramides in dry skin of patients with AD was signifi cantly lower than that in normal individuals and the percentage of ceramide 1 was decreased to 52% compared with healthy controls.
