Atopic dermatitis skin tends to be easily irritated and appears dry. These clinical peculiarities correspond to impaired barrier function and to increased transepidermal water loss (TEWL) values. A few studies suggest that a reduced amount of total
ceramides (especially of
ceramide 1) is responsible for functional abnormalities of the skin of
atopic dermatitis patients. The aim of this study was to analyze the relationship between epidermal
lipids and barrier impairment in the skin of patients with
atopic dermatitis. The quantity of
ceramides,
cholesterol sulphate and free
cholesterol of 47 patients with
atopic dermatitis and 20 age- and sex-matched healthy subjects was assessed by
cyanoacrylate stripping and thin layer chromatography. Capacitance and TEWL were recorded at the same site of the
lipid sample. In patients with
atopic dermatitis, the levels of
ceramide 1 and 3 were significantly lower and values of
cholesterol significantly higher with respect to healthy subjects. Moreover, the CER/CH ratio was significantly lower with respect to normal skin. Patients with active signs of
eczema also had higher TEWL values and lower capacitance values. By contrast, patients with no active signs of
atopic dermatitis had a normal barrier function and intermediate values of
ceramides and cholesterols, when compared to patients with
atopic dermatitis with active lesions and normal subjects. The quantity of
ceramide 3 was significantly correlated with TEWL impairment. These findings suggest that a decrease in
ceramides in the stratum corneum is involved in barrier impairment in
atopic dermatitis skin. Our data confirm those of other authors and support the view that impaired metabolism of
ceramides may be the cause of dry skin and impaired barrier function in
atopic dermatitis.