The chemistry, function and (patho)physiology of stratum corneum barrier ceramides

Abstract

Research on understanding of the chemistry, function and (patho)-physiology of stratum corneum (SC) lipids and especially ceramides has evolved over the last two decades. This has been made successful through the application of separation techniques that have become increasingly more sophisticated, and it has become increasingly evident that our understanding of these molecules remains in its infancy. Thirteen classes of ceramides with over 300 and possibly up to 1000 distinct ceramide species have been identified suggesting an exquisitely subtle relationship between the types of ceramides and physical and chemical behaviour. Nevertheless, research has demonstrated the importance of the correct SC lipid lamellar architecture with conformationally-ordered lipid bilayers, the presence of long-chain ceramides, as either free or covalently bound lipids, greater quantities of phytosphingosine-containing ceramides and a high SC lipid/protein ratio is essential for optimal barrier function. These features are known to change in a variety of physiological and pathophysiological conditions. Clearly, there is more to be learned but as we further decipher the complexity of SC lipids and understand their individual roles in the SC, we will learn how to better treat the disorders of cornification.R esum e Des recherches sur la compr ehension de la chimie, de la fonction et de la (patho)physiologie des lipides du stratum corneum (SC) et en particulier des c eramides ont evolu e au cours des deux derni eres d ecennies. Cela a et e couronn e de succ es grâce a l'application de techniques de s eparation qui sont devenues de plus en plus sophistiqu ees et il est devenu de plus en plus evident que notre compr ehension de ces mol ecules reste a ses d ebuts. Treize classes de c eramides avec plus de 300 et eventuellement jusqu' a 1000 esp eces distinctes de c eramide ont et e identifi ees, ce qui sugg ere une relation tr es subtile entre les types de c eramides et le comportement physicochimique. N eanmoins, la recherche a d emontr e l'importance de l'exactitude de l'architecture lamellaire lipidique du SC avec la conformation en bicouches lipidiques, de la pr esence de c eramides a longue chaîne, qu'ils soient libres ou li es de fac ßon covalante, de la plus grandes quantit es de c eramides contenant de la phytosphingosine et un taux elev e de lipides / prot eines du SC, est essentiel pour une fonction de barri ere optimale. Ces caract eristiques sont connues pour varier suivant les conditions physiologiques et pathophysiologiques. De toute evidence, il y a plus a apprendre, mais a mesure que nous d echiffrions davantage la complexit e des lipides du SC et que nous comprenons leurs rôles individuels dans le SC, nous apprendrons a mieux traiter les troubles de la k eratinisation.

Skin acidification with a water‐in‐oil emulsion (pH 4) restores disrupted epidermal barrier and improves structure of lipid lamellae in the elderly

“…7,25 Seasonal changes, race, body site and aging significantly influence the lipid lamellar architecture and composition. 9,[26][27][28][29] The age group studied here (63.4 AE 6.8 years) showed a disturbed lipid lamellar organization which is in line with published work. 9,27,29 Using Lipbarvis sampling in addition to standard instrumental measurements, we were able to show that lamellar organization clearly improved after 4-week treatment with the pH 4 emulsion.…”

The effect of photodamage on the female Caucasian facial stratum corneum corneome using mass spectrometry‐based proteomics

“…Transglutaminases cross‐link CE proteins but they also help to increase the hydrophobicity of the envelope through esterification with ceramides . These ceramides are derived from the very long chain linoleoyl omega‐hydroxy ceramides (CER [EOS]) . However, the linoleoyl moiety is first oxidized by two lipoxygenases, 12R‐LOX and eLOX3, before being hydrolysed and then the free omega‐hydroxy ceramides being utilized by transglutaminase 1 .…”

“…Transglutaminases cross-link CE proteins but they also help to increase the hydrophobicity of the envelope through esterification with ceramides [31]. These ceramides are derived from the very long chain linoleoyl omega-hydroxy ceramides (CER [EOS]) [11].…”

Dry skin and the use of leave‐on products in nursing care: A prevalence study in nursing homes and hospitals

“…The outermost keratinized skin layer, the stratum corneum, is mainly responsible for the level of skin hydration (Paul et al, ). Natural moisturizing factors in the corneocytes and intercellular lipids are crucial elements of the stratum corneum contributing to skin integrity by limiting transepidermal water loss (Moore & Rawlings, ; Paul et al, ). An imbalance in the composition of different components of the stratum corneum and changes in keratinization processes can lead to a disturbed skin barrier function and finally to skin dryness (White‐Chu & Reddy, ).…”