Supplementation with eicosapentaenoic acid and linoleic acid increases the production of epidermal ceramides in in vitro canine keratinocytes

Background: Few studies have investigated the effects of essential fatty acids on the production of epidermal ceramide (CER) in canine keratinocytes. Hypothesis/objectives: To investigate the effects of eicosapentaenoic acid (EPA) and linoleic acid (LA) supplementation on the production of CERs using an in vitro canine keratinocyte culture system. Methods and materials: Canine keratinocyte cells (MSCEK) were incubated with high Ca²⁺[1.8 mM calcium chloride (CaCl₂)] serum-free medium, supplemented with 3 µM EPA and 15 µM LA when the cells showed confluency. On Day 8 of application, lipid analysis using high-performance thin layer chromatography and real-time PCR for detecting glucosylceramide synthase and ceramidase were performed. Results: It was revealed that the amounts of CER (EOS) (combination of ω-hydroxy fatty acids and sphingosines), CER [EOP] (combination of ω-hydroxy fatty acids and phytosphingosines) and a mixture of CER [NS] (combination of nonhydroxy fatty acids and sphingosines) and [NDS] (combination of nonhydroxy fatty acids and dihydrosphingosines), as well as total CERs, were significantly increased in cells incubated with EPA and LA compared to those of the vehicle, with increased mRNA expression of glucosylceramide synthase. Conclusions and clinical importance: These findings suggest that EPA and LA can potentially alter the CER profile of the skin and this may contribute to its epidermal barrier function in canine skin.