Stratum corneum lipid structure: Insights from NMR and FTIR spectroscopic studies

The lipid matrix of the stratum corneum (SC) provides several critical physiological functions, the most important of which is protecting the body from dehydration. In recent years our knowledge of lipid composition in the stratum corneum, and of the enzymatic pathways by which these lipids are generated, has increased significantly. It is now well established, for example, that the SC lipid matrix consists primarily of saturated free fatty acids, cholesterol, and arange of ceramide species but does not appear to contain any phospholipids or significant amounts of unsaturated lipids [1]. As discussed elsewhere, many elegant X-ray and electron microscopy studies have yielded a picture of the stratum corneum lipid matrix in which these extracellular lipid components can be seen to consist of stacked lamellae, within which are embedded the corneocytes of the SC. It is obvious that full comprehension of SC barrier physiology necessitates a detailed, understanding of lateral and transverse lipid organization at the molecular level. However, a detailed description of molecular organization, and the specific structural and functional role of lipid heterogeneity in the SC, remain to be experimentally determined.