Epidermal Lipid Homeostasis

Stratum corneum lipids, which are enriched in sphingolipids, free fatty acids, and cholesterol, are required for epidermal barrier function. When the epidermal permeability barrier is perturbed, the transepidermal water loss returns to normal by 24-48 hours in parallel with the reappearance of stratum corneum lipids, derived from secreted lamellar bodis and accelerated lipid synthesis. Recent evidence shows that topical application of individual lipids interferes with barrier recovery while complete mixtures of cholesterol, fatty acids, and ceramides facilitate recovery after barrier disrupton. Metabolic imbalances and perturbed barrier function can be either the cause or the consequences of the pathobiology of scaling disease. Many skin diseases relating cornification and dryness are indeed related to abnormality of one or several combinations of lipids. Recently the cytokines which have changed during barrier recovery seem to be important in understanding of epidermal lipid homeostasis as well as barrier recovery.