Moisturizing at a molecular level – The basis of Corneocare

Abstract

This review covers the last 20 years of research we and our collaborators have conducted on ethnic differences in facial skin moisturization placed in historical context with previous research. We have focussed particularly on the biochemical and cellular gradients of the stratum corneum (SC) with the aim of discovering new skin moisturization and SC maturation mechanisms, identifying new technologies and/or providing conceptual innovations for ingredients that will improve our understanding and treatment of dry skin. Specifically, we discuss gradients for corneodesmosomes and proteases, corneocyte phenotypeinducing enzymes, filaggrin and natural moisturizing factor (NMF), and barrier lipids. These gradients are interdependent and influence greatly corneocyte maturation. The interrelationship between corneodesmolysis and the covalent attachment of ωhydroxy ceramides and ωhydroxy fatty acids to the corneocyte protein envelope forming the corneocyte lipid envelope is especially relevant in our new understanding of mechanisms leading to dry skin. This process is initiated by a linoleoyl-ωacyl ceramide transforming enzyme cascade including 12R lipoxygenase (12R-LOX), epidermal lipoxygenase-3 (eLOX3), epoxide hydrolase 3 (EPHX3), short-chain dehydrogenase/reductase family 9C member 7 (SDR9C7), ceramidase and transglutaminase 1. Our research has opened the opportunity of using novel treatment systems for dry skin based on lipids, humectants, niacinamide and inhibitors of the plasminogen system. It is clear that skin moisturization is a more complex mechanism than simple skin hydration. RésuméCette revue couvre 20 années de recherche que nous avons menées avec nos collaborateurs sur les différences ethniques d'hydratation de la peau du visage, en regard du contexte historique de recherches antérieures. Nous avons en particulier focalisé sur les gradients biochimiques et cellulaires du stratum corneum (SC) dans le but de découvrir de nouveaux mécanismes d'hydratation et de maturation du SC, et avons identifié de de nouvelles technologies et/ou apporté des conceptsThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Clinical efficacy of a multilamellar cream on skin physiology and microbiome in an epidermal stress model: A controlled double‐blinded study (Part I)1

“…A significant increase in SC hydration was obvious already at day 2 after acute barrier disruption for both creams; however, on day 14, the verum was more efficient than the placebo in elevating skin surface hydration (Figure 1b). The latter has been widely recognized as a crucial mechanism for the regulation of epidermal homeostasis and recovery [4,[46][47][48][49]. The pH decrease over time showed only a trend but did not reach statistical significance.…”

A comprehensive comparison of facial skin hydration based on capacitance and conductance measurements in Chinese women

“… Diagram representing the relative values (0%–100%) of the Skicon (blue line) and the Corneometer (red line) for the individual 30 facial test sites [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. [Colour figure can be viewed at wileyonlinelibrary.com ] …”

“…The reasons for the differences in the relative skin hydration status between the two instruments can be a result of multiple causes. Besides the differences in the electrical measurement principles (conductance vs. capacitance), these mainly include the biochemistry of the type and quantity of molecules on and in the skin, the thickness of the SC, and the different cellular anatomy of the test sites [ 5 , 6 ].…”

“…The main workhorse instruments are based on the electrical properties of the skin, such as conductance and capacitance measurements, and several authors have compared the relative merits of the different instruments [ 2 , 3 , 4 ]. However, skin hydration assessment is complex and is complicated by the physiological differences in SC biochemistry and cellular biology amongst different body sites, such as the thickness of the SC, differences in skin lipids and natural moisturizing factor levels and corneocyte maturation status [ 5 , 6 ]. This is relevant not only for comparison between different body sites but even on different zonal regions of the face [ 7 , 8 , 9 , 10 ].…”

Some thoughts about Anthony V. Rawlings and hydration and barrier function of the skin

“…This included contributions of Gray and Yardley and their collaborators [2,3] and the epidermal lipid groups from Unilever [4,5] and the University of Iowa [6][7][8][9]. This material is updated in Tony's most recent review [10]. The 1994 review also included major sections on filaggrin [11] and natural moisturizing factor (NMF) and desquamation [12].…”