Effects of sphingolipid extracts on the morphological structure and lipid profile in an in vitro model of canine skin

Abstract

Ceramides (CER) are essential sphingolipids of the stratum corneum (SC) that play an important role in maintaining cutaneous barrier function. Skin barrier defects occur in both human beings and dogs affected with atopic dermatitis, and have been associated with decreased CER concentrations and morphological alterations in the SC. The aim of the present study was to investigate the changes induced by three different sphingolipid extracts (SPE-1, SPE-2 and SPE-3) on the morphological structure and lipid composition of canine skin, using an in vitro model, whereby keratinocytes were seeded onto fibroblast-embedded collagen type I matrix at the air–liquid interface. Cell cultures were supplemented with SPE-1, SPE-2, SPE-3 or vehicle (control) for 14 days. The relative concentrations of lipids were determined by ultra-performance liquid chromatography coupled to mass spectrometry. The ultrastructural morphology of samples was examined by transmission electron microscopy. SPE-1 induced significant elevation in total CERs, CER[NS], CER[NDS], CER[NP], CER[AS], CER[AP], CER[EOS] and CER[EOP] subclasses, whereas SPE-2 induced a significant elevation in total CER, CER[AP] and CER[EOS] compared with control conditions. Ultrastructural analysis revealed an increase in lamellar-lipid structures in the SC of SPE-1-treated samples. The findings demonstrated that SPE-1 stimulates production of CERs, as shown by changes in lipid composition and ultrastructural morphology. Thus, SPE-1 contributes to the formation of a well-organised SC and represents a potential therapeutic target for improving skin barrier function in atopic dermatitis.