Retaining Skin Barrier Function Properties of the Stratum Corneum with Components of the Natural Moisturizing Factor—A Randomized, Placebo-Controlled Double-Blind In Vivo Study

Abstract

The influence of a topically applied formulation containing components of natural moisturizing factor (NMF) on barrier-related parameters of the stratum corneum (SC) was investigated in vivo using confocal Raman microspectroscopy in a randomized, placebo-controlled double-blind study on 12 volunteers for 14 days. This method allowed for the elucidation of subtle differences between the verum and the placebo even though the components of the verum naturally occur in the SC. This differentiation is not possible non-invasively by conventional methods. In this study, we found that the applied verum and placebo formulations disrupted the equilibrium of water, NMF and lipids in the SC. The adverse effects of the formulation could be mitigated by incorporating it into a simplified supplementation of NMF molecules. As a long-term effect, the amount of strongly bound water increases at 30–40% SC depth (p < 0.05) and the amount of weakly bound water decreases at 30–40% SC depth (p < 0.05) for the verum. This supplement was also unexpectedly able to prevent intercellular lipids (ICL) disorganization in selected depths. In the long term, the verum treatment limited the lateral disorganization of the ICL to the upper 20% SC depth. Further research is required to elucidate the interplay of these factors in the SC, to better understand their contribution to the equilibrium and barrier function of the skin. This understanding of the interaction of these naturally occurring components could help in the future to develop and optimize topical treatments for diseases like psoriasis, atopic dermatitis, ichthyosis where the skin barrier is disrupted.

Current Views on Noninvasive in vivo Determination of Physiological Parameters of the Stratum Corneum Using Confocal Raman Microspectroscopy

“…Additionally to the composition, the noninvasive evaluation of the influence of topically applied cosmetic or medical formulations on the parameters of the SC is up to date and was previously only realized ex vivo using Raman spectroscopy [73-75]. The development of the above described algorithms allows the investigations of the influence of topically applied cosmetic or medical formulations on the components and physiological parameters of the human SC in vivo and noninvasively using confocal Raman microspectroscopy [76-79], which is in great demand for cosmetic and pharmaceutical industries.…”

“…Additionally to the composition, the noninvasive evaluation of the influence of topically applied cosmetic or medical formulations on the parameters of the SC is up to date and was previously only realized ex vivo using Raman spectroscopy [73][74][75]. The development of the above described algorithms allows the investigations of the influence of topically applied cosmetic or medical formulations on the components and physiological parameters of the human SC in vivo and noninvasively using confocal Raman microspectroscopy [76][77][78][79], which is in great demand for cosmetic and pharmaceutical industries. Determination of the SC's Components Among most concentrated lipids, keratin, and water, characterized with strongly intense Raman bands, analysis of Raman spectra makes it possible to determine depth profiles of additional molecular components of the SC, such as NMF molecules, urocanic acid, urea, lactate [70,72,80,81], as well as melanin and carotenoids [70,82,83].…”

Galactomyces Ferment Filtrate Potentiates an Anti-Inflammaging System in Keratinocytes

“…Recent advances in skin biology not only provide rational evidence and a strategy for understanding the beneficial effects of cosmetic ingredients, but can also help to improve the efficacy of skincare products in treating various skin complaints. Ceramide- and NMFs-containing skincare products are good examples of treatments that significantly alleviate signs of dry skin, even in inflammatory skin diseases [ 51 , 52 , 53 ]. GFF is a functional cosmetic ingredient whose adoption was inspired by the empirical observation that sake brewers often had youthful and soft skin on their hands.…”

“…Moisturizers commonly contain both occlusives and humectants to increase skin hydration and decrease TEWL [ 50 ]. In addition to the basic occlusives and humectants, recent advancements in skin biology point to the beneficial potential of topical applications of ceramides or NMFs in upregulating the skin-barrier function [ 51 , 52 , 53 ].…”

Physiological, Pathological, and Circadian Factors Impacting Skin Hydration

“…Age-related reductions in skin hydration have been reported, but the mechanisms responsible are not completely understood [ 28 , 45 ]. In the SC, water is mostly present in the corneocytes and bound to NMF; however a smaller amount is bound to the polar head groups of lipids inside intercellular lamellas [ 54 ]. The lateral organization of lipids in the SC allow for its function as a permeable barrier and enable water retention.…”