The role of ceramides in skin barrier function and the importance of their correct formulation for skincare applications

Ceramides are a family of lipids constituted by a sphingoid base and a fatty acid. In the skin, they are mainly present in the stratum corneum where, with cholesterol and free fatty acids, they constitute the inter-corneocyte lipids. With the other lipid groups, they play a key role in the formation of dense lamellar structures between adjacent corneocytes, collectively ensuring the vital efficient barrier to water evaporation and protection from foreign agents<acute accent> penetration. Changes in ceramide level and relative composition, with potential impairment of lipid arrangement, have been evidenced in different skin conditions and skin diseases. Therefore, use of suitably formulated ceramides has been proposed for topical treatment to help re-structure damaged lipid arrangement and repair impaired skin barrier function. Nonetheless, the formulation of ceramides in products necessitates specific processes such as heating to high temperature before their introduction in the final formula. In this review on the structure, the role and the potential of ceramides for skincare, we point out the necessity of rigorous process when formulating ceramides into the final product. We demonstrate the counterproductive effects of undissolved ceramides on skin barrier repair capacity of the formulas, when assessed in different in vitro models of disrupted skin barrier. Les c & eacute;ramides sont une famille de lipides constitu & eacute;e d'une base sphingo & iuml;de et d'un acide gras. Dans la peau, ils sont principalement pr & eacute;sents dans la couche corn & eacute;e o & ugrave;, avec le cholest & eacute;rol et les acides gras libres, ils constituent les lipides inter-corn & eacute;ocytes. Avec les autres groupes de lipides, ils jouent un r & ocirc;le cl & eacute; dans la formation de structures lamellaires denses entre les corn & eacute;ocytes adjacents, assurant collectivement la barri & egrave;re efficace vitale contre l'& eacute;vaporation de l'eau et la protection contre la p & eacute;n & eacute;tration des agents & eacute;trangers. Des modifications du taux de c & eacute;ramides et de la composition relative, avec une alt & eacute;ration potentielle de l'arrangement lipidique, ont & eacute;t & eacute; observ & eacute;es dans diff & eacute;rentes affections cutan & eacute;es et maladies cutan & eacute;es. Par cons & eacute;quent, l'utilisation de c & eacute;ramides formul & eacute;s de mani & egrave;re appropri & eacute;e a & eacute;t & eacute; propos & eacute;e pour un traitement topique afin d'aider & agrave; restructurer la disposition des lipides endommag & eacute;s et & agrave; r & eacute;parer la fonction de barri & egrave;re cutan & eacute;e alt & eacute;r & eacute;e. N & eacute;anmoins, la formulation des c & eacute;ramides dans les produits n & eacute;cessite des processus sp & eacute;cifiques tels que le chauffage & agrave; temp & eacute;rature & eacute;lev & eacute;e avant leur introduction dans la formule finale. Dans cette revue sur la structure, le r & ocirc;le et le potentiel des c & eacute;ramides pour les soins de la peau, nous soulignons la n & eacute;cessit & eacute; d'un processus rigoureux lors de la formulation des c & eacute;ramides dans le produit final. Nous d & eacute;montrons les effets contre-productifs des c & eacute;ramides non dissous sur la capacit & eacute; de r & eacute;paration de la barri & egrave;re cutan & eacute;e des formules, lorsqu'ils sont & eacute;valu & eacute;s dans diff & eacute;rents mod & egrave;les in vitro de barri & egrave;re cutan & eacute;e perturb & eacute;e. Changes in ceramide level have been evidenced in different skin conditions and skin diseases. The use of suitably formulated ceramides has been proposed for topical treatment. Attention has to be paid to the correct way of incorporating ceramides into formulation.image