Upregulation of gene expression levels of ceramide metabolic enzymes after application of sphingomyelin-based liposomes to a three-dimensional cultured human epidermis model.

ABSTRACT

BACKGROUND/AIMS: We have previously reported that the application of sphingomyelin-based liposomes (SM-L) to a three-dimensional cultured skin model increase the content of ceramides NS, NP, AS and AP. However, the mechanism responsible for these increased ceramide levels was not identified. METHODS: SM-L and sphingomyelinase (SMase) were combined and incubated at 37 °C for 24 h. SM-L were also applied to three-dimensional cultured skin for 24 h and quantification of SMase and ß-glucocerebrosidase (ß-GCase) mRNA expression levels performed using real-time PCR. Additionally, three dimensional cultured skin was incubated with SM-L and the ß-GCase inhibitor conduritol B epoxide (CBE) and the ceramide content determined by high performance thin layer chromatography. RESULTS: We observed generation of ceramide NS after reaction of SM-L and SMase. However, the other ceramide classes were not detected. Notably, SMase and ß-GCase mRNA expression levels were significantly increased in cells of the skin model following application of SM-L. The levels of ceramides NS, NP, AS and AP were decreased by treatment with CBE. However, only ceramide NS was significantly increased by treatment with CBE and SM-L in combination. CONCLUSION: These findings indicate that application of SM-L to cultured skin upregulates the expression of SMase and ß-GCase and increases ceramide content.