Effects of sphingomyelin/ceramide ratio on the permeability and microstructure of model stratum corneum lipid membranes |
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Authors: | Petra Pullmannová ,Klá ra Staňková ,Marké ta Pospí &scaron ilová ,Barbora &Scaron kolová ,Jarmila Zbytovská ,Kateřina Vá vrová |
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Affiliation: | 1. Skin Barrier Research Group, Charles University in Prague, Faculty of Pharmacy, Heyrovského 1203, 500 05 Hradec Králové, Czech Republic;2. Institute of Chemical Technology Prague, Technická 5, 166 28 Prague, Czech Republic |
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Abstract: | The conversion of sphingomyelin (SM) to a ceramide (Cer) by acid sphingomyelinase (aSMase) is an important event in skin barrier development. A deficiency in aSMase in diseases such as Niemann–Pick disease and atopic dermatitis coincides with impaired skin barrier recovery after disruption. We studied how an increased SM/Cer ratio influences the barrier function and microstructure of model stratum corneum (SC) lipid membranes. In the membranes composed of isolated human SC Cer (hCer)/cholesterol/free fatty acids/cholesteryl sulfate, partial or full replacement of hCer by SM increased water loss. Partial replacement of 25% and 50% of hCer by SM also increased the membrane permeability to theophylline and alternating electric current, while a higher SM content either did not alter or even decreased the membrane permeability. In contrast, in a simple membrane model with only one type of Cer (nonhydroxyacyl sphingosine, CerNS), an increased SM/Cer ratio provided a similar or better barrier against the permeation of various markers. X-ray powder diffraction revealed that the replacement of hCer by SM interferes with the formation of the long periodicity lamellar phase with a repeat distance of d = 12.7 nm. Our results suggest that SM-to-Cer processing in the human epidermis is essential for preventing excessive water loss, while the permeability barrier to exogenous compounds is less sensitive to the presence of sphingomyelin. |
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Keywords: | aSMase, acid sphingomyelinase acylCer, ω-O-acyl ceramide/s Cer, ceramide/s AD, atopic dermatitis Chol, cholesterol from lanolin FFA, free fatty acid/s IND, indomethacin HPTLC, high performance thin layer chromatography hCer, ceramides of the human stratum corneum LPP, long periodicity phase PBS, phosphate-buffered saline SPP, short periodicity phase CholS, sodium cholesteryl sulfate SM, sphingomyelin eSM, sphingomyelin, chicken egg bmSM, sphingomyelin, bovine milk SEM, standard error of mean SC, stratum corneum TH, theophylline, anhydrous TLC, thin layer chromatography |
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