A metabolite of dietary glucosylceramide from pineapples improves the skin barrier function in hairless mice

Glucosylceramide (GlcCer) has various effects such as skin moisturizing, improvement of atopic dermatitis, and enhancement of skin barrier function. However, the mechanism of GlcCer on skin barrier function remains unclear. In this study, the effect of GlcCer from pineapples (P-GlcCer) on dry skin protection and intestinal immunity was investigated using HR-1 hairless mice fed on a special diet and an in vitro co-culture model consisting of intestinal epithelial Caco-2 and macrophage RAW264.7. The oral administration of P-GlcCer showed an improvement in skin barrier function and enhancement of interleukin-23p19 mRNA (Il23a) expression in the small intestine. Il23a expression in LPS-stimulated RAW264.7 cells was enhanced by the purified GlcCer in P-GlcCer. Furthermore, pretreatment of Caco-2 with a β-glucocerebrosidase or a ceramidase inhibitor suppressed the enhancement of Il23a expression, but a sphingosine kinase inhibitor did not. It was demonstrated that not P-GlcCer itself but the intestinal metabolite 4,8-sphingadienine ameliorated dry skin symptoms.