Modeling lipid layers of atopic skin and observation of changes in lipid layer properties with changes in ceramide content

Background: Studies have shown that there is a high correlation between atopic dermatitis and decrease in ceramide content in the lipid bilayer of skin. Moreover, it has been shown that the reduction in ceramide content in the stratum corneum is unique to atopic dermatitis, indicating that there are particular structural differences between the lipid bilayers of normal and atopic skin. Aim: This study aimed to compare the lipid bilayer of the atopic skin with that of the healthy skin and to establish a structural model of the lipid bilayer for atopy. Methods: Molecular dynamics simulations were performed using NAMD 2.8. Models of lipid bilayers of normal skin and atopic skin, and a model of lipid bilayer containing only ceramide were built with CHARMM-GUI. The thickness, area occupied per lipid, and alignment of lipids were compared among the three models. Potential mean force (PMF) of the sodium laureth sulfate (SLES) on lipid bilayers was calculated to predict the affinity between SLES and lipid bilayers. Results: Potential mean force calculations showed that the lipid bilayer of atopic skin was able to absorb the surfactant more easily than that of normal skin. Conclusions: When the ceramide ratio is low, the thickness of lipid bilayer is reduced and its structure is weakened. Other structural differences between the lipid layers of normal and atopic skin included increased area per lipid and poor alignment of lipids. Further, the atopy lipid bilayer model was found to absorb more SLES than the normal skin lipid bilayer model.