An inverse relationship between ceramide synthesis and clinical severity in patients with psoriasis

Ceramides play major roles in maintaining the epidermal barrier. It has been suspected that the depletion of ceramides, associated with disrupted barrier function in the epidermis, leads to the clinical manifestation of dryness and inflammation seen in patients with psoriasis. The aim of the present study was to determine the relationship between the level of ceramide synthesis in the epidermis and the clinical severity in patients with psoriasis. Samples from lesional and unlesional epidermis obtained from psoriasis patients were incubated with [C-14]serine, an initiator of ceramide synthesis. Total ceramide was fractionated using high performance thin layer chromatography, and the radioactivity was measured. The clinical severity of psoriasis was graded according to the psoriasis area and severity index scoring system. The level of ceramide synthesis in the lesional epidermis of patients was significantly lower than that in the unlesional epidermis and bore a negative correlation with the clinical severity of psoriasis. The present results suggest that the decreased level of ceramide synthesis in the epidermis contributes to the clinical severity of psoriasis.