Ceramides (
sphingolipids) are the main polar
lipids of the stratum corneum and play an important role in skin barrier function, cell adhesion and epidermal differentiation. In view of the function of
ceramides in normal skin, this study aimed to assess their levels in patients with various types of hereditary
ichthyosis, in which epidermal homeostasis is markedly abnormal. Stratum corneum samples were collected from 80 patients and 23 normal controls, and the intercellular and
lipid envelope
ceramides were analysed by high-performance thin-layer chromatography. The covalently bound
ceramides (
ceramides A and B) of the
lipid envelope were present in all patients studied, and showed no significant differences from control samples. Total
ceramides (ceramides 1-6) were decreased in
bullous ichthyosiform erythroderma, which is presumably a secondary phenomenon similar to that seen in patients with
atopic dermatitis. Patients with non-erythrodermic
lamellar ichthyosis showed a marked decrease in levels of the important acylceramide,
ceramide 1, whereas those with other types of autosomal recessive
ichthyosis (limited
lamellar ichthyosis and non-
bullous ichthyosiform erythroderma) had mean levels similar to the controls.
Ceramide 1 deficiency may therefore define a subgroup within the autosomal recessive
ichthyoses.
Sjögren-Larsson syndrome (SLS) shows a deficiency of both acyl-
ceramides (
ceramides 1 and 6), which would seem likely to disrupt the normal skin barrier function. Furthermore,
glucosylceramides (
cerebrosides) are known to be deficient in the neural tissue of patients with SLS. The relationship of these
ceramide abnormalities to the underlying
fatty alcohol oxidoreductase defect remains uncertain, but they may provide an interesting link between the nerve damage and cutaneous abnormalities seen in this rare neurodermatosis.