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Anthony V. Rawlings has had 30+ years of experience in the general area of skin science. He has many scientific publications, and his work has been highly cited. He has made major contributions to our understanding of skin physiology, including xerosis and hydration, barrier function, desquamation, the corneocyte envelope, physical chemistry of stratum corneum lipids, photodamage and ethnic variation. He has held management positions with several companies in the US and UK, established AVR Consulting in 2002 and maintained a long-standing relationship with colleagues at University College London. His time as the Editor in Chief of the International Journal of Cosmetic Science was pivotal in the development of the journal. He worked hard and succeeded in getting the IJCS included in the PubMed database., (© 2024 Society of Cosmetic Scientists and Societe Francaise de Cosmetologie.)

Breast milk contains numerous factors that are involved in the maturation of the immune system and development of the gut microbiota in infants. These factors include transforming growth factor-β1 and 2, immunoglobin A, and lactoferrin. Breast milk factors may also affect epidermal differentiation and the stratum corneum (SC) barrier in infants, but no studies examining these associations over time during infancy have been reported. In this single-center exploratory study, we measured the molecular components of the SC using confocal Raman spectroscopy at 0, 1, 2, 6, and 12 months of age in 39 infants born at our hospital. Breast milk factor concentrations from their mothers' breast milk were determined. Correlation coefficients for the two datasets were estimated for each molecular component of the SC and breast milk factor at each age and SC depth. The results showed that breast milk factors and molecular components of the SC during infancy were partly correlated with infant age in months and SC depth, suggesting that breast milk factors influence the maturation of the SC components. These findings may improve understanding of the pathogenesis of skin diseases associated with skin barrier abnormalities.

Recently, microneedling as a cosmetic product has attracted attention as one way to improve skin barrier function and moisturizing function to reduce wrinkle formation. However, some cases of erythema and edema have been reported as side effects. In order to develop safer microneedle cosmetics, we investigated whether microneedles can improve skin barrier function and moisturizing function even when applied in a non-invasive manner that does not penetrate the stratum corneum. We established the condition of non-penetrating microneedle application on reconstructed human full-thickness skin models and examined the effect on the skin models when microneedles were applied under this condition. Microneedle application increased the gene expression of serine palmitoyltransferase long chain base subunit (SPTLC) 3, filaggrin, and transglutaminase 1. The amount of ceramide produced by SPTLC was also increased by microneedle application. Gene expression of filaggrin-degrading enzymes and the amount of free amino acids, a product of filaggrin degradation, were also increased by microneedling. These results suggest that non-invasive microneedle application can improve skin barrier function and moisturizing function by increasing the amount of ceramide and natural moisturizing factors.

Background: Topical use of dexpanthenol presents well-established moisturizing properties and maintenance and repair of the skin barrier function, however, its exact action mechanisms are not completely elucidated. In this context, Confocal Raman Microspectroscopy is an optical method that enables non-invasive and non-destructive in vivo analysis with the sensitive acquisition of molecular changes in different skin layers. Herein, the aim was to evaluate the effects of topical dexpanthenol on the components and physiological parameters of the stratum corneum (SC)., Materials and Methods: Ten healthy female subjects underwent skin evaluation by means of a Confocal Raman Spectrometer Skin Analyzer 3510. Spectral data were obtained from the skin of the anterior forearm region, before and 2 h after applying a cosmetic formulation containing or not containing 5% dexpanthenol., Results: Semiquantitative analysis of the natural moisturizing factor showed a significant decrease in content after 2 h of topical dexpanthenol application, while the analysis of the lamellar organization of intercellular lipids and the secondary structure of keratin showed a significant increase in hexagonal organization of lipids at the first half of the SC and a significant increase in β-pleated sheet conformation of keratin., Conclusion: Effects of topical dexpanthenol on SC suggest a contribution in increasing fluidity of both lipidic and protein components of the SC and are compatible with dexpanthenol activity in maintaining adequate physiological conditions and preventing transepidermal water loss. This study also contributes to the elucidation of action mechanisms and other concurrent biochemical processes., (© 2023 The Authors. Skin Research and Technology published by John Wiley & Sons Ltd.)

The multiple protective functions of the skin derive from the interactions between epithelial skin and immune cells as well as the commensal microbiota. Developed in the last trimester of intra-uterine life, the skin barrier adapts dynamically after birth. Specific differences in the structure and physiology have been disclosed between infant and adult skin. The stratum corneum of infants is thinner and structured by thicker corneocytes with a more anisotropic surface in comparison to adult skin. Lower levels of the natural moisturizing factor and its constituents, together with the increased protease activity in the epidermis result in dry baby skin and ongoing adaptation of the desquamation to the extra-uterine environment. Infant epidermis is characterized by an accelerated proliferation rate and clinically competent permeability barrier in term neonates, despite the higher baseline values of transepidermal water loss in infants. The skin surface of newborns is less acidic, which could increase susceptibility to diaper and atopic dermatitis. Immediately after birth, skin is colonized by commensal bacteria-a process dependent on the mode of delivery and of major importance for the maturation of the immune system. Skin bacterial diversity and dysbiosis have been related to different pathology such as atopic and seborrheic dermatitis. This paper focuses on the ongoing structural, functional and biochemical adaptation of the human skin barrier after birth. We discuss the interactions on the 'skin barrier/ microbiota/ immune system' axis and their role in the development of competent functional integrity of the epidermal barrier., (© 2023 The Authors. International Journal of Cosmetic Science published by John Wiley & Sons Ltd on behalf of Society of Cosmetic Scientists and Societe Francaise de Cosmetologie.)

Background: Bleomycin hydrolase (BH), which is expressed in the stratum granulosum and lower stratum corneum (SC), is involved in final filaggrin degradation. Furthermore, BH plays an essential role in producing free amino acids, which constitute the majority of natural moisturizing factors (NMF). However, the effects of BH expression and protease activity on human skin aging remain unclear., Objective: This study was designed to evaluate the activity and expression patterns of BH in SC extracts from healthy young and elderly individuals., Methods: SC samples were collected by tape stripping. BH activity was assessed by measuring the citrulline aminopeptidase activity. BH expression was determined by Western blotting, and NMF was quantified by liquid chromatography/mass spectrometry. Skin barrier function was determined by measuring SC hydration, transepidermal water loss (TEWL), and skin pH., Results: The activity and expression of BH were higher in the elderly skin than in young skin, and BH activity was correlated with BH expression levels. Evaluation of the NMF showed that the levels of total amino acids, such as glycine, serine, aspartic acid, citrulline, pyrrolidone carboxylic acid (a metabolite of glutamic acid), and trans-urocanic acid (a metabolite of histidine), were significantly higher in elderly skin than in young skin. Moreover, SC hydration and TEWL were significantly lower in elderly, indicating dry skin, and pH was significantly higher in elderly, indicating greater skin alkalinization., Conclusion: These results suggest that BH activity and expression, as well as NMF amino acids, increase in elderly people as compensatory mechanisms against dry skin., Competing Interests: Conflict of interest statement None of the authors declare any conflicts of interest., (Copyright © 2023. Published by Elsevier B.V.)

Purpose: Urea as an ingredient in topical skin applications can aid skin integrity and hydration and have keratolytic, anti-fungal, anti-bacterial, and anti-pruritic effects. Skin conditions that urea-containing formulations have been utilized to treat include hand eczema/dermatitis, seborrheic dermatitis and psoriasiform dermatoses of the scalp. Two monocentric, simple blind, observational studies were carried out in healthy participants to examine the efficacy and safety of two urea-containing products in these skin conditions., Patients and Methods: Study 1 tested the actions of a commercially available 30% urea topical cream on hand eczema. The product was applied ≥2/day for 28 ±2 days. Transepidermal water loss, skin redness, skin hydration, and participant ratings of efficacy and qualities were assessed prior to first product application and on days 14 and 29. Study 2 tested the actions of a commercially available foaming product containing 10% urea on seborrheic dermatitis and scalp psoriasiform dermatoses. The product was applied ≥2/day for 28 ±2 days. Desquamation index and surface occupied by squames, analysis of extracted squames, microscopic assessment of scalp photos and participant ratings of product efficacy and qualities was carried out prior to first product application and on days 14 and 29., Results: In Study 1 (n = 20 females), results showed a significant (p < 0.05) decrease in transepidermal water loss, with an increase in hydration level of the upper skin layers, and a decrease in skin redness. In Study 2 (n = 13 females, 7 males), product use led to significant (p < 0.05) decreases in desquamation measures and dryness. In both studies, the majority of participants "agreed" or "slightly agreed" that the product had good efficacy and was easy to apply. No adverse reactions were reported., Conclusion: These findings point to the utility of urea in topically applied vehicles for hand eczema, seborrheic dermatitis, and psoriasiform dermatoses., Competing Interests: AD’a was the principal investigator in this study and was funded by RELIFE S.r.l. (Menarini Group). LC and WKC are consultants for RELIFE S.r.l. (Menarini Group). WKC has served as an advisory board member for RELIFE S.r.l. (Menarini Group). The authors report no other conflicts of interest in this work., (© 2022 Celleno et al.)

Introduction: This study investigated the role of natural polymers as moisturizers with low toxicity and biodegradability in the cosmetic and pharmaceutical industries. We isolated a polysaccharide extract from Dendrobium candidum (D. candidum) and determined its efficacy in skin hydration when used as an active cosmetic ingredient., Methods: The molecular weight distribution of D. candidum polysaccharides was analyzed via gel permeation chromatography (GPC). We performed real-time reverse transcription PCR (RT-PCR) and western blotting assays to investigate the physiological mechanism of the polysaccharides extracted from D. candidum (PDC). Based on in vitro data, the efficacy of PDC in improving skin condition was tested on the face of 21 volunteers., Results: The expression of filaggrin (FLG), caspase-14, and bleomycin hydrolase, which are the major components contributing to skin hydration, was significantly increased in the PDC-treated group. Further, the PDC upregulated the mRNA expression of occludin and claudin-1, which play a key role in epidermal barrier function. In addition, a topical application of PDC markedly increased skin hydration and improved trans-epidermal water loss (TEWL) and skin elasticity after 2 weeks., Conclusions: It is the first study reporting the efficacy of PDC-mediated FLG mechanism associated with positive skin hydration. PDC can be used as an active ingredient in moisturizers. Long-term application of PDC-based moisturizers may result in significant improvement in elasticity and barrier function., (© 2021 Australian Veterinary Association.)

Background: Stratum corneum (SC) hydration is vital for the optimal maintenance and appearance of healthy skin. In this context, we evaluated the efficacy of an NMF-enriched moisturizer containing 10% urea on different aspects of SC hydration of dry skin., Material and Methods: In two clinical studies, the hydration efficacy of the moisturizer in comparison to its vehicle was investigated. In the first study, 42 subjects applied the moisturizer and the vehicle to one lower leg each. Thirty minutes and 24 h after this single treatment, SC hydration was measured by corneometry. Volunteers also rated skin moisturization and evaluated product properties. In the second study, 27 subjects each treated one forearm twice daily for 2 weeks with the moisturizer and the vehicle. Then, depth-resolved water-absorption spectra were measured by near-infrared confocal spectroscopic imaging (KOSIM IR)., Results: The moisturizer exerted a superior hydrating effect compared to the vehicle. KOSIM IR measurements show that, compared to the vehicle, the moisturizer significantly improved the water gradient in the SC from the surface to a depth of 15 μm. Moreover, the moisturizer received high acceptance ratings from the volunteers and was preferred to the vehicle., Conclusion: The humectants applied in the investigated moisturizer improved SC water content in total and as a function of depth. The combination of depth-resolved data (KOSIM IR) with classical corneometry provides an integrated concept in the measurement of skin hydration, rendering both methods complementary. These findings were in line with the volunteers` self-assessments of the moisturizer properties that are relevant to treatment adherence., (© 2022 Beiersdorf AG. Skin Research and Technology published by John Wiley & Sons Ltd.)

The molecular composition of human skin is altered due to diseases, which can be utilized for non-invasive sampling of biomarkers and disease diagnostics. For this to succeed, it is crucial to identify a sampling formulation with high extraction efficiency and reproducibility. Highly hydrated skin is expected to be optimal for increased diffusion of low-molecular-weight biomarkers, enabling efficient extraction as well as enhanced reproducibility as full hydration represents a well-defined endpoint. Here, the aim was to explore water-based formulations with high water activities, ensuring satisfactory skin hydration, for non-invasive sampling of four analytes that may serve as potential biomarkers, namely tryptophan, tyrosine, phenylalanine, and kynurenine. The included formulations consisted of two hydrogels (chitosan and agarose) and two different liquid crystalline cubic phases based on the polar lipid glycerol monooleate, which were all topically applied for 2 h on 35 healthy subjects in vivo. The skin status of all sampling sites was assessed by electrical impedance spectroscopy and transepidermal water loss, enabling explorative correlations between biophysical properties and analyte abundancies. Taken together, all formulations resulted in the successful and reproducible collection of the investigated biomarkers. Still, the cubic phases had an extraction capacity that was approximately two times higher compared to the hydrogels.

Introduction: Xerosis cutis is characterized by a decreased stratum corneum (SC) hydration and an impaired skin barrier function. Urea, the most prevalent natural moisturizing factor (NMF), is currently considered the gold standard. Its efficacy can further be increased by combining urea with other NMF and skin barrier lipids (SBLs)., Objective: We set out to evaluate physiological effects of a novel functional moisturizer containing 10% urea, additional NMF components, and a combination of SBLs on skin hydration and skin barrier integrity on a cellular and phenotypic level in female volunteers suffering from xerosis., Methods: Two double-blind, vehicle-controlled clinical studies were conducted. In the first study, 44 female subjects having very dry body skin applied the moisturizer or its vehicle twice daily to their volar forearms. Twenty-four hours after a single product application as well as 24 h after 2 weeks of treatment, SC hydration was measured by corneometry. Skin barrier function was assessed by transepidermal water loss 24 h and 48 h after 2 weeks of regular use. Twenty-four hours after 2 weeks of application, skin tape stripping was performed, and urea content was determined in the 3rd strip by means of high-performance liquid chromatography/tandem mass spectrometry. In the second study, 22 women with self-reported very dry skin applied the moisturizer or vehicle twice daily to their volar forearms for 2 weeks. Then, suction blister samples were obtained for gene expression analysis using RT-PCR., Results: Application of the actives led to significantly improved skin hydration and barrier function at all points in time. Compared to the vehicle, application of the moisturizer for 2 weeks resulted in a significant increase in SC urea content. Relative gene expression data revealed significant upregulation of genes associated with skin barrier function, hydration, differentiation, and lipid metabolism compared to the vehicle-treated area., Conclusions: Overall, our data demonstrate that the functional moisturizer provides an adequate bioavailability of urea and a beneficial biophysical impact on xerotic skin. Topical treatment with a combination of urea and additional NMF as well as SBL can modify mRNA expression of important epidermal genes stimulating cellular processes and functions. The well-tolerated novel functional moisturizer stimulates molecular mechanisms involved in skin hydration and barrier function and is a profoundly effective treatment option for xerosis cutis., (© 2021 The Author(s). Published by S. Karger AG, Basel.)

The natural moisturizing factor (NMF) is a mixture of small water-soluble compounds present in the upper layer of the skin, stratum corneum (SC). Soaking of SC in water leads to extraction of the NMF molecules, which may influence the SC molecular properties and lead to brittle and dry skin. In this study, we investigate how the molecular dynamics in SC lipid and protein components are affected by the removal of the NMF compounds. We then explore whether the changes in SC components caused by NMF removal can be reversed by a subsequent addition of one single NMF component: urea, pyrrolidone carboxylic acid (PCA) or potassium lactate. Samples of intact SC were investigated using NMR, X-ray diffraction, infrared spectroscopy and sorption microbalance. It is shown that the removal of NMF leads to reduced molecular mobility in keratin filaments and SC lipids compared to untreated SC. When the complex NMF mixture is replaced by one single NMF component, the molecular mobility in both keratin filaments and lipids is regained. From this we propose a general relation between the molecular mobility in SC and the amount of polar solutes which does not appear specific to the precise chemical identify of the NMF compounds., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

The stratum corneum (SC) is the outermost layer of the epidermis and plays an important role in maintaining skin moisture and protecting the skin from the external environment. Ceramide and natural moisturizing factor (NMF) are the major SC components that maintain skin moisture. In this study, we investigated whether the oral intake of enzymatically decomposed AP collagen peptides (APCPs) can improve skin moisture and barrier function by assessing changes in the ceramide and NMF contents in the SC after APCP ingestion with the aim to develop a skin functional food. Fifty participants orally ingested APCP (1000 mg) or placebo for 12 weeks, and then, skin hydration and skin texture were evaluated. SC samples were collected to analyze skin scaling, ceramide, and NMF contents. Participants in the APCP group exhibited improved skin moisture content by 7.33% ( p = 0.031) and roughness by -4.09% ( p = 0.036) when compared with those in the placebo group. NMF content; the amounts of amino acids (AA), including glycine and proline; and AA derivatives were significantly increased in the APCP group (31.98 μg/mg protein) compared to those in the placebo group (-16.01 μg/mg protein) ( p = 0.006). The amounts of total ceramides and ceramide subclasses were significantly higher in the APCP group than in the placebo group ( p = 0.014). In conclusion, our results demonstrate that APCP intake improves skin moisture and increase the ceramide and NMF contents in the SC, thereby enhancing the skin barrier function.

Collection of skin very top layer, called stratum corneum, by tape stripping and the analysis of stratum corneum components by mass spectrometry provides multiple advantages for clinical studies that aim to understand the origins of allergic skin diseases and food allergy. However, such a methodology has multiple challenges on the way of complex stratum corneum analysis when molecules of different polarity are needed to be analyzed from minimal amount of skin tape strips. This review provides an overview of current knowledge about lipid and polar molecules in the skin, discusses challenging aspects of sample processing when dealing with skin tape strips, and provides some guidance towards approaches that generate complex, quantitative, normalized to total sample protein data that fit best the purpose of analysis of stratum corneum components for the purpose of clinical trials., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Patch test (PT) reactions to thiuram mix (TM) and fragrance mix (FM) I or II without concomitant reactions to their single constituents are potentially caused by the irritant properties of the mixes., Objective: Comparing inflammatory profiles of PT reactions to TM, FM I, FM II, and their constituents and assessing their potential in discrimination of irritant and allergic reactions., Patients and Methods: Levels of 14 cytokines and natural moisturizing factor (NMF) were determined in stratum corneum samples collected from PT reactions to TM, FM I or II, their constituents, and petrolatum (pet.) control sites in 36 individuals., Results: Levels of interleukin (IL)-16, chemokine (CXC motif) ligand (CXCL) 8, CXCL10, chemokine (CC motif) ligand (CCL) 17, and CCL22 were significantly increased in reactions (+, ++) to thiurams and fragrances compared to their petrolatum. controls, except for PT reactions to FM I/II with negative breakdown testing in which, however, decreased levels of NMF were observed. In doubtful reactions to FM I/II with negative breakdown testing, NMF was significantly lower than in petrolatum controls., Conclusions: PT reactions to thiurams and fragrances indicate a Th2-skewed inflammation. The inflammatory profiles suggest that weak or doubtful FM I/II reactions without accompanying reaction to a constituent were irritant. IL-16 might be suitable to distinguish irritant from allergic reaction., (© 2020 The Authors. Contact Dermatitis published by John Wiley & Sons Ltd.)

(1) Background: The aim of the study was to evaluate the effect of pure lecithins in comparison to a conventional surfactant on skin in vivo. (2) Methods: Physiological skin parameters were evaluated at the beginning and the end of the study (day 1 and day 4) ( n = 8, healthy forearm skin) with an Aquaflux ® , skin-pH-Meter, Corneometer ® and an Epsilon ® sensor. Confocal Raman spectroscopy was employed to monitor natural moisturizing factor, urea and water content of the participants' skin. Tape strips of treated skin sites were taken and the collected corneocytes were subjected to atomic force microscopy. Circular nano objects were counted, and dermal texture indices were determined. (3) Results: Transepidermal water loss was increased, and skin hydration was decreased after treatment with SDS and LPC80. Natural moisturizing factor and urea concentrations within the outermost 10 µm of the stratum corneum were lower than after treatment with S75 or water. Dermal texture indices of skin treated with SDS were higher than skin treated with water (control). (4) Conclusions: Results suggest very good (S75) or good (LPC80) skin-tolerability of lecithin-based surfactants in comparison to SDS and encourage further investigation.

Introduction: We aimed to investigate the effect of orally ingested collagen peptides (CPs) on skin condition and elucidate their mechanism of action., Methods: A randomized, placebo-controlled, double-blind trial was conducted in 99 healthy Japanese women, aged 35-50 years. The subjects were randomized into 3 groups (33 subjects/group) to receive 1 or 5 g of CP or placebo once daily for 12 weeks. Skin water content, transepidermal water loss (TEWL), skin elasticity, and skin thickness were evaluated before treatment and after 4, 8, and 12 weeks of treatment. The level of natural moisturizing factor (NMF) constituents in the stratum corneum (SC) was quantified before treatment and after 12 weeks of treatment., Results: Oral ingestion of CP increased the water content in the SC and epidermis and decreased TEWL. Furthermore, the NMF level in the SC was increased. However, skin elasticity and skin thickness remained unchanged., Conclusions: The improvement in skin water content following the oral ingestion of CP can be attributed to an increase in the level of NMF in the SC., Trial Registration: UMIN000030375 (retrospectively registered)., (© 2021 S. Karger AG, Basel.)

Background:  Impaired skin barrier is an important etiological factor in atopic dermatitis (AD). The structural protein filaggrin (FLG) plays a major role in maintenance of the competent skin barrier and its deficiency is associated with enhanced susceptibility to mechanical injury. Here we examined biomechanical characteristics of the corneocytes in children with AD and healthy controls. Methods:  We recruited 20 children with AD and 7 healthy children. They were genotyped for filaggrin gene ( FLG ) loss-of-function mutations. Stratum corneum was collected from clinically unaffected skin by adhesive tapes. Cell stiffness (apparent elastic modulus, Ea) was determined by atomic force microscopy and filaggrin degradation products (NMF) by liquid chromatography. Skin barrier function was assessed through trans-epidermal water loss (TEWL) and disease severity by the SCORing Atopic Dermatitis (SCORAD) tool. Results:  Corneocytes collected from AD patients showed a decreased elastic modulus which was strongly correlated with NMF and TEWL, but not with SCORAD. As compared with healthy controls, AD patients had reduced TEWL and NMF levels regardless of FLG mutations. NMF was strongly correlated with TEWL. Conclusion:  Our findings demonstrate that AD patients have decreased corneocyte stiffness which correlates with reduced levels of filaggrin degradation products, NMF and skin barrier function. Altered mechanical properties of the corneocytes likely contribute to the loss of mechanical integrity of the SC and to reduced skin barrier function in AD., Competing Interests: No competing interests were disclosed., (Copyright: © 2020 Haftek M et al.)

Background:  Impaired skin barrier is an important etiological factor in atopic dermatitis (AD). The structural protein filaggrin (FLG) plays a major role in maintenance of the competent skin barrier and its deficiency is associated with enhanced susceptibility to mechanical injury. Here we examined biomechanical characteristics of the corneocytes in children with AD and healthy controls. Methods:  We recruited 20 children with AD and 7 healthy children. They were genotyped for filaggrin gene ( FLG ) loss-of-function mutations. Stratum corneum was collected from clinically unaffected skin by adhesive tapes. Cell stiffness (apparent elastic modulus, Ea) was determined by atomic force microscopy and filaggrin degradation products (NMF) by liquid chromatography. Skin barrier function was assessed through trans-epidermal water loss (TEWL) and disease severity by the SCORing Atopic Dermatitis (SCORAD) tool. Results:  Corneocytes collected from AD patients showed a decreased elastic modulus which was strongly correlated with NMF and TEWL, but not with SCORAD. As compared with healthy controls, AD patients had reduced TEWL and NMF levels regardless of FLG mutations. NMF was strongly correlated with TEWL. Conclusion:  Our findings demonstrate that AD patients have decreased corneocyte stiffness which correlates with reduced levels of filaggrin degradation products, NMF and skin barrier function. Altered mechanical properties of the corneocytes likely contribute to the loss of mechanical integrity of the SC and to reduced skin barrier function in AD., Competing Interests: No competing interests were disclosed., (Copyright: © 2020 Haftek M et al.)

Background: One of the most important steps people can take in reducing the spread of bacteria and viruses is washing the hands with soap and water. Frequent washing, required in certain occupations, can lead to skin dryness, chapping, and itching., Materials and Methods: In vivo confocal Raman spectroscopy was used to study short-term effects of hand washing on product deposition, lipid acyl chain structural disordering, and extraction of important skin components such as natural moisturizing factors, cholesterol, ceramides, amino acids, and changes in skin hydration. Effects of use of either soap, synthetic detergent, or triethanolamine (TEA)-soap/ glycerin were compared at two water temperatures., Results: Soap use resulted in significant deposition at all depths to 20 μm at 25°C and at the surface and 2 μm at 37°C. Significant decreases were observed in relative amounts of all skin components studied. NMF levels were not changed. Skin dehydration was observed for use of soap at 37°C., Conclusions: Short-term effects of frequent hand washing can be monitored with in vivo confocal Raman spectroscopy. Effects of frequent washing may be reduced with lower wash temperature and products. Skin dehydration is not associated with lipid chain disordering., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: The objective of this study was to perform noninvasive analysis of skin proteins in a healthy Chinese population using label-free nanoflow liquid chromatography-mass spectrometry (nLC-MS)., Materials and Methods: Five consecutive tape strippings were obtained from the volar forearm skin of healthy Chinese subjects. Proteins were extracted, and trypsin-digested peptides were analyzed by a nanochromatography instrument coupled to an Orbitrap Fusion Tribrid mass spectrometer. Data-dependent acquisition allowed protein identification, which was performed by using Proteome Discoverer software (v2.2)., Results: In this study, we identified 80 common proteins that were expressed in the skin of healthy Chinese volunteers and divided these proteins into 16 categories, including keratins, cornified envelope proteins, and enzymes associated with substance metabolism. These proteins were closely associated with multiple functions of the skin barrier., Conclusion: This study provides a noninvasive method to analyze healthy human epidermal proteins, which are closely associated with the skin barrier. In addition, this study provides a reference for further studies on the application of proteomic technologies to investigate the role of human epidermal proteins in health and disease., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The superficial layer of the skin, the stratum corneum (SC), consists of corneocytes surrounded by lipid regions and acts as a protective barrier for the body against water loss, toxic agents and microorganisms. As most substances permeate the stratum corneum through the lipid regions, lipid organization is considered crucial for the skin barrier function. Here, we investigate the potential of in vivo confocal Raman spectroscopy to describe the composition and organization of the SC. Confocal Raman spectroscopy is finding increasing use in the characterization of skin in biomedical, pharmaceutical and cosmetic applications. In this work, we analyze the spectra using chemometric methods and obtain principal components that correspond to the primary skin constituents: protein (keratin), natural moisturizing factor (NMF), water and lipid contributions in both ordered (orthorhombic) and disordered structural organization. By identifying these important components of the SC, these results highlight the utility of this in vivo, non-invasive, and depth resolved tool at the forefront of skin research., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background/objectives: Ultraviolet (UV) radiation damages the stratum corneum (SC) and disrupts the skin barrier. The damaged skin changes in the molecular composition of the SC, including its water content. However, it is difficult to examine the in vivo SC changes with existing methods, so those have not been well characterized. Therefore, we investigated in vivo changes of UV-induced SC damage using confocal Raman spectroscopy., Method: We irradiated the volar forearm of 10 subjects with 0.5, 1, and 1.5 minimal erythemal doses of UV radiation. Then, we examined erythema, the transepidermal water loss (TEWL), the water content, the natural moisturizing factor (NMF), and the lipids of the skin., Results: After UV irradiation, erythema and TEWL of the skin were both increased. The bound water content of the SC was also increased following UV irradiation. The NMF of the SC revealed different tendencies. All free amino acids (FAAs) of the NMF were increased after UV irradiation, except proline. trans-urocanic acid, pyrrolidone carboxylic acid, lactate, and urea, which are NMF components produced by the subsequent catabolism of FAAs and sweat, were decreased after UV irradiation. The amount of ceramide in the SC was also decreased after UV exposure, while cholesterol was increased., Conclusions: The bound water content of the SC was increased by UV exposure along with increasing TEWL, several NMF components, and cholesterol. These in vivo results for UV-damaged SC obtained via Raman spectroscopy could be applied to research with regard to protecting the SC from UV radiation and treating UV-damaged SC., (© 2019 S. Karger AG, Basel.)

Background: Moisturizers are topical products designed to improve and maintain the skin barrier function and to help prevent dry skin., Materials and Methods: A new moisturizer (Ceramide cream) was formulated containing ingredients which mimic the skin's own natural moisturizing systems. Corneometry was performed at baseline, 2, 4, 6 and 24 hours following a single application of Ceramide cream to healthy skin, and compared to three reference moisturizers available over-the-counter, and placebo. Transepidermal water loss (TEWL) was also measured following a single application of Ceramide cream compared to baseline, and its safety was assessed by repeat insult patch test, ophthalmologist and pediatric testing., Results: A single topical application of either the Ceramide cream or the three reference moisturizers resulted in a significant increase in skin hydration over time ( P <0.001). The placebo cream did not significantly increase skin hydration at any time point. At 24 hours post-application, skin hydration measured for Ceramide cream was significantly greater ( P <0.05) than that measured for all three of the reference moisturizers tested. Ceramide cream was also found to significantly decrease TEWL ( P <0.001) over 24 hours, and was shown to be non-sensitizing to the skin of both adults and children and non-irritating to the skin, eyes and related eye area., Conclusion: Ceramide cream increases skin hydration and improves barrier function which may make it suitable for use on dry skin., Competing Interests: Disclosure FS, TMB and KAG are employed by Ego Pharmaceuticals, Pty Ltd. The authors report no other conflicts of interest in this work.

Porcine skin is widely used as a human skin model in dermatology. For both, porcine stratum corneum (SC) ex vivo and human SC in vivo, the hydrogen bonding states of water, the secondary and tertiary structures of keratin, the natural moisturizing factor (NMF) concentrations and the intercellular lipids' (ICL) lateral organization are investigated depth-dependently using confocal Raman microscopy. The SC depth profiles show that porcine SC ex vivo is characterized by lower hydrogen bonding states of water (10%-30% SC depth), lower NMF concentration in the whole SC, more β-sheet form of keratin (10%-90% SC depth), more folded tertiary keratin structures (30%-70% SC depth) and higher hexagonal lateral packing order of ICL (10%-50% SC depth) compared to human SC in vivo. The results clearly show a higher value of skin barrier function of human SC in vivo than of porcine SC ex vivo. Thus, the human SC in vivo is less permeable for lipophilic and hydrophilic substances than porcine SC ex vivo. Considering the porcine SC as an ex vivo model of human SC in vivo, these findings should be taken into consideration., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this study, stratum corneum (SC) depth profiles of hydrogen bound water molecule types, intercellular lipid (ICL) ordering, concentration of natural moisturizing factor (NMF) and keratin folding/unfolding properties are investigated in vivo for older (mean 50 years old) and younger (mean 29 years old) human skin using confocal Raman microscopy. The results show that the SC of the older group is modestly thicker (p<0.1), has more hydrogen bound water molecules at the depth 10-30% of the SC thickness (p<0.05), has a higher ordered organization of ICL (p<0.1) and higher concentration of NMF (p<0.05) at the depth 20-40% of the SC thickness compared to the younger group. This study also reveals, that the hydrogen bonding state of water highly correlates with NMF and the lateral structure of ICL but not with keratin's folding/unfolding properties. The presented results let suggest, that the decreased trans-epidermal water loss (TEWL) with increasing age cannot be sufficiently explained by only the increased SC thickness, but additionally by the increase of ICL ordering, higher NMF concentration and thus larger amount of hydrogen bound water molecules at the depth 20-40% of the SC thickness., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Introduction: An adequate hydration level is essential to maintain epidermal barrier functions and normal physiological activities of skin tissues. Diverse moisturizing agents and pharmaceutical formulations for dermal deliveries have thus extensively been investigated. This review comprehensively discusses scientific outcomes of moisturizing agents and pharmaceutical vehicles for skin moisturization, thereby providing insight into designing innovative pharmaceutical formulations for effective skin moisturization., Areas Covered: We discussed the functions of various moisturizing agents ranging from conventional creams to novel moisturizers which has recently been explored. In addition, novel pharmaceutical formulations for efficient dermal delivery of the moisturizers, in particular, nanocarriers, were discussed along with their uses in commercial products., Expert Opinion: Although various moisturizing agents have demonstrated their promising effects, exploitation of pharmaceutical formulations for their dermal delivery have been limited to few commonly used moisturizing agents. Thus, combinatorial investigation of novel moisturizers and pharmaceutical vehicles should be further conducted. As a new concept for improving skin moisturization, skin regeneration technologies using therapeutic cells have recently shown great promise for skin moisturization, but major challenges remain, such as efficient delivery and prolonged survival of such cells. Thus, novel approaches for improving skin moisturization require continuous efforts of pharmaceutical scientists to address the remaining problems.

Phytosphingosine (PHS) is a sphingoid that is a key component of phytoceramides NP, AP and EOP. PHS has been known to have anti-inflammation and antimicrobial activities and to stimulate epidermal differentiation. In addition, it is reported that PHS treatment notably increased phytoceramide content in keratinocytes. In this study, we tried to investigate whether PHS has any effect on the maturation of corneocytes such as formation of cornified envelope and natural moisturizing factor (NMF) that is also an essential event during the formation of skin barrier, stratum corneum. Special focus was made on the filaggrin (FLG) metabolism that is directly responsible for NMF production. PHS increased the expression of essential keratinocyte differentiation genes such as involucrin and transglutaminase 1 in cultured human keratinocytes. Interestingly, the expressions of FLG, caspase 14 and bleomycin hydrolase, all of which involved in NMF production in corneocytes, were significantly induced by PHS treatment in vitro. The effect of PHS on FLG metabolism was manifested as the increase of pyrrolidone carboxylic acid and skin hydration in vivo human skin. Results showed PHS had skin moisturizing effect by modulating FLG metabolic pathways and suggested to be an essential role in coordinated formation of the corneocyte envelope and NMF within.

Background: The irritant sodium lauryl sulfate (SLS) is known to cause a decrease in the stratum corneum level of natural moisturizing factor (NMF), which in itself is associated with changes in corneocyte surface topography., Objective: To explore this phenomenon in allergic contact dermatitis., Methods: Patch testing was performed on patients with previously positive patch test reactions to potassium dichromate (Cr), nickel sulfate (Ni), methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI), or p-phenylenediamine. Moreover, a control (pet.) patch and an irritant (SLS) patch were applied. After 3 days, the stratum corneum from tested sites was collected, and NMF levels and corneocyte morphology, expressed as the amount of circular nanosize objects, quantified according to the Dermal Texture Index (DTI), were determined., Results: Among allergens, only MCI/MI reduced NMF levels significantly, as did SLS. Furthermore, only MCI/MI caused remarkable changes at the microscopic level; the corneocytes were hexagonal-shaped with pronounced cell borders and a smoother surface. The DTI was increased after SLS exposure but not after allergen exposure., Conclusions: MCI/MI significantly decreased NMF levels, similarly to SLS. The altered corneocyte morphology suggests that skin barrier damage plays a role in the pathogenesis of MCI/MI contact allergy. The DTI seems to differentiate reactions to SLS from those to the allergens tested, as SLS was the only agent that caused a DTI increase., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: This work aimed to design, synthesize and characterize replacement natural moisturizing factor (NMF) composed of modified hygroscopic linear amino acids to pre-empt or repair skin barrier dysfunction., Methods: Following synthesis and characterization, thermo-gravimetric analysis and quantum mechanics molecular modelling quantified and depicted water binding to the new compounds. Deliquescence relative humidity demonstrated the water-scavenging ability of the compounds, whereas snake skin moisturizing studies showed they increased water uptake into snake skin., Results: From thermal analysis, N-hydroxyglycine showed greatest water-holding capacity followed by N-hydroxyserine, l-homoserine and α-hydroxyglycine; coupled with quantum mechanics molecular modelling, between 8 and 12 molecules of water could associate with each molecule of either N-hydroxyglycine, N-hydroxyserine or l-homoserine. All of our modified amino acids were efficacious and induced similar or greater water uptake compared with the established moisturizing compounds hyaluronic acid, glycerine and urea in snake skin. Incorporated at 10% in Oilatum, N-hydroxyserine induced >200% greater moisture uptake into dry snake skin compared to treatment with water alone, with efficacy related to the molecule structure and ability to bind to 12 water molecules. Oilatum cream spiked with all our unnatural amino acid hydrotropes increased water uptake into snake skin compared with Oilatum alone. The compound series was designed to elucidate some structure - efficacy relationships. Amino acid chirality did not affect the water-holding capacity but did affect uptake into skin. Compounds with high melting points and bond energies tended to decrease water-holding capacity. With isosteric replacement, the more electronegative atoms gave greater water-holding capacities., Conclusions: This work demonstrates the potential of unnatural amino acid hydrotropes as skin moisturizers and has developed some predictive 'rules' for further design and refinement of chemical structures., (© 2016 The Authors. International Journal of Cosmetic Science published by John Wiley & Sons Ltd on behalf of Society of Cosmetic Scientists and Société Française de Cosmétologie.)

Background: Knowledge of the ethnic differences and effects of photodamage on the relative amounts of natural moisturizing factor (NMF) together with filaggrin processing enzymes in facial stratum corneum is limited. Our aim was to characterize the activities of calpain-1 (C-1), bleomycin hydrolase (BH) and the levels of pyrrolidone carboxylic acid (PCA) as a marker for total NMF levels and to relate them to plasmin activities and corneocyte maturation., Methods: Enzyme activities, PCA levels and corneocyte maturation were determined from facial tape strippings of photoexposed cheek and photoprotected post-auricular areas (PA) of healthy Caucasian (C), Black African (BA) and albino African (AA) female subjects living in South Africa., Results: PCA concentration levels were of the order AA > BA > C subjects, and the highest activities of BH were present in the AA subjects. BH activities were greater on the photoexposed sites for the BA and C subjects, but they were only numerically elevated in the AA subjects. Photoprotected sites had an increase in C-1 activity in pigmented groups (C and BA), whereas in the AA subjects, the opposite was measured. Plasmin activities were greater on the cheek compared with the PA site for the AA and C subjects, but the activity was low in the BA subjects. In both test sites, the AA, but not the BA and C subjects, had smaller, parakeratotic and less mature corneocytes., Conclusion: Variation in PCA levels has been found for different ethnic groups in this study (AA > BA > C subjects). The values in the AA subjects are surprising as one might expect that the lack of pigmentation, and thereby increased photodamage, might lead to lower levels. Increased BH, but not C-1 activity, was observed in the AA subjects indicating that BH is associated with PCA production to a greater extent. Surprisingly, corneocyte maturation is still impaired with elevated PCA levels in AA subjects. The higher levels of plasmin and BH activities on the cheeks, especially for AA and C subjects, suggest that they can be used as markers for epidermal photodamage., (© 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.)

Purpose: Reverse iontophoresis (RI) is one of the potential techniques used to monitor the concentration of various analytes in body fluids non-invasively. Transdermal extraction of potassium is investigated using RI. In the present work, the effect of potassium on stratum corneum (SC) during RI, feasibility of RI for continuous monitoring of potassium, and use of potassium as internal standard in RI, are investigated., Methods: Tape stripping experiment is carried out to find potassium concentration in SC. RI is carried out continuously for 180 min without passive diffusion and after passive diffusion for 60 min. Skin impedance measurements are done at 20 Hz and 20 kHz., Results: Potassium is found to be in the range 300-650 nmol/cm(2) on SC by tape stripping experiment. Correlation coefficient between blood potassium and extracted potassium through RI after passive diffusion (R(2) = 0.5870) is more than without passive diffusion (R(2) = 0.5117). The skin impedance measurement shows that RI has more effect on SC than superficial layer of SC during RI., Conclusion: The present investigations conclude that it is possible to monitor potassium continuously through RI and using potassium as internal standard in RI., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Fruit-derived organic compounds and detergents are relevant exposure factors for occupational contact dermatitis in the food industry. Although individuals with atopic dermatitis (AD) are at risk for development of occupational contact dermatitis, there have been no controlled studies on the effects of repeated exposure to multiple irritants, relevant for the food industry, in atopic skin., Objectives: The aim of the study was to investigate the outcomes of repeated exposure to a fruit-derived organic acid and a detergent in AD compared to healthy volunteers., Methods: The volunteers were exposed to 2.0% acetic acid (AcA) and/or 0.5% sodium lauryl sulfate (SLS) in controlled tandem repeated irritation test. The outcomes were assessed by measurements of erythema, transepidermal water loss (TEWL) and natural moisturizing factor (NMF) levels., Results: In the AD volunteers, repeated AcA exposure led to barrier disruption and significant TEWL increase; no significant differences after the same exposure in the healthy controls were found. Repeated exposure to SLS and the irritant tandems enhanced the reactions and resulted in a significantly higher increase in TEWL in the AD compared to the control group. Cumulative irritant exposure reduced the NMF levels in both groups., Conclusions: Differences in the severity of irritant-induced barrier impairment in atopic individuals contribute to the risk for occupational contact dermatitis in result of multiple exposures to food-derived irritants and detergents., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Natural moisturizing factor (NMF), principally comprised of hygroscopic amino acids and derivatives that absorb moisture from the surrounding environment, serves as the primary humectant of the stratum corneum (SC). Acute barrier disruption has been shown to differentially affect the concentration of NMF in the SC. This study measured the recovery kinetics of NMF after mechanical damage of the SC, which is not well understood., Methods: The study population included 20 healthy female volunteers (18-72-year old) with no history of dermatological disorders. Transepidermal water loss (TEWL), erythema, and SC water and NMF were measured at all sites before abrasion, 30 min following abrasion, and 1-3, 6, 8, and 10 days following abrasion. Measurements obtained from the abraded site were compared with those obtained from an untreated site., Results: As expected, both TEWL and erythema increased significantly with abrasion. Erythema and TEWL values remained higher at the abraded site for 2 and 6 days, respectively, after abrasion. No changes in NMF component levels in the SC were observed at 30 min after abrasion. One day following abrasion, reduced levels of glycine, histidine pH4, trans-urocanic acid (tUca) pH4, and tUca pH8 were observed. In addition, a significantly lower level of serine was observed at the abraded site 2 and 6 days following abrasion. Within 8 days after abrasion, these components returned to levels comparable to those observed in untreated skin. Throughout the study, no differences were observed in the level of water in the SC., Conclusion: These results demonstrate that acute barrier disruption induced by mechanical abrasion has relatively little impact on biochemical events responsible for NMF generation. Though reductions in certain NMF components were observed, abrasion had no measureable effect on SC water content over the duration of the study. This implies that the reduced NMF components may not contribute substantially to water retention in the SC. The reduced components belong to a group of NMF molecules thought to be principally derived through degradation of S-100 proteins in the epidermis. NMF components measured in this study that are derived from sweat and/or urea cycling were not impacted. These data imply that while abrasion elicits clinical signs of barrier disruption within the SC, effects on its biochemical constituents and ability to retain water are relatively minor., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The skin plays a key role in protecting the body from the environment and from water loss. Cornified envelope (CE) and natural moisturizing factor (NMF) are considered as the primary regulators of skin hydration and barrier function. The CE prevents loss of water from the body and is formed by cross-linking of several proteins. Among these proteins, filaggrin is an important protein because NMF is produced by the degradation of filaggrin. Proteases, including matriptase and prostasin, stimulate the generation of filaggrin from profilaggrin and caspase-14 plays a role in the degradation of filaggrin. This study elucidated the effects of an ethanol extract of Boesenbergia pandurata (Roxb.) Schltr., known as fingerroot, and its active compound panduratin A on CE formation and filaggrin processing in HaCaT, human epidermal keratinocytes. B. pandurata extract (BPE) and panduratin A significantly stimulated not only CE formation but also the expression of CE proteins, such as loricrin, involucrin, and transglutaminase, which were associated with PPARα expression. The mRNA and protein levels of filaggrin and filaggrin-related enzymes, such as matriptase, prostasin, and caspase-14 were also up-regulated by BPE and panduratin A treatment. These results suggest that BPE and panduratin A are potential nutraceuticals which can enhance skin hydration and barrier function based on their CE formation and filaggrin processing.

Background: Dry skin in atopic dermatitis (AD) mainly results from barrier impairment due to deficiency of ceramide and natural moisturizing factors including pyrrolidone carboxylic acid (PCA) in stratum corneum (SC). Caspase-14 cleaves filaggrin monomers to free amino acids and their derivatives such as PCA, contributing natural moisturizing factors. Cytokines in the corneocytes represent cutaneous inflammation severity of AD patients., Object: To analyze the correlations of PCA, caspase-14 and cytokines in corneocytes with clinical severity, barrier function and skin inflammation, those were quantitated., Methods: A total of 73 persons were enrolled: 21 patients with mild AD, 21 with moderate-to-severe AD, 13 with X-linked ichthyosis (XLI) as a negative control for filaggrin gene (FLG) mutation, and 18 healthy controls. Skin barrier functions such as basal transepidermal water loss (TEWL), stratum corneum (SC) hydration and skin surface pH were measured. To collect corneocytes, stripping with D-squame discs was done on lesional and non-lesional skin. And then PCA was isolated from D-squame discs and quantitated by LC-MS/MS. Cytokine assays were performed., Results: The quantity of PCA and caspase-14 was decreased in inflammatory lesions compared to non-lesion in AD patients. And the amounts of PCA and caspase-14 in the lesion of AD patients correlated with clinical severity as determined by eczema area and severity index score and the skin barrier functions. Also, the expressions of TNF-α and IL-13 inversely correlated with PCA quantity., Conclusion: The quantity of PCA or caspase-14 in the corneocytes of the lesional skin of AD patients reflects the clinical severity, skin barrier function and the degree of lesional inflammation., (Copyright © 2014 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

Objective: In a previous paper (Lu et al., International Journal of Cosmetic Science, in press), we reported that in comparison with normal skin, cosmetic dry skin characteristically has a thicker stratum corneum (SC) with weaker barrier quality. Our goal here was to obtain a more complete picture of the difference between normal and cosmetic dry skin, by further analysing the data collected from the same clinical study to address two additional aspects of skin: the amount and depth profile of natural moisturizing factor (NMF) and the cohesivity of the SC., Method: The SC samples were collected by sequential tape stripping in a clinical study consisting of 64 healthy Caucasian female subjects with either normal or cosmetic dry skin. Protein and free amino acids (FAA) on tape strips were extracted and analysed using high-throughput methods. The level of pyrrolidone carboxylic acid (PCA), the prominent component of NMF, was detected using HPLC analysis., Results: It was found that dry skin had significantly lower ratios of FAA/protein and PCA/protein across the stripped SC depth, corresponding to a lower hydration level compared with the normal skin. Our results indicated that filaggrin to FAA hydrolysis occurred deeper in dry skin and at a lower level compared with normal skin. In addition, the mass of proteins stripped from dry skin subjects was significantly higher than that from the normal skin counterpart, especially for the first 10-12 tape strips., Conclusion: Our results showed that, compared with normal skin, cosmetic dry skin had a lower NMF level across the SC depth and a lower cohesivity. Such results suggested that NMF levels are critical for cosmetic skin conditions, and lower NMF production may be associated with dry skin. In addition, the NMF level and its depth profile and the SC cohesivity are useful clinical end points for assessing the efficacy of dry skin treatments such as skin moisturizers., (© 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.)

Objectives: Natural moisturizing factor (NMF) serves as the primary humectant of the stratum corneum (SC), principally comprised of hygroscopic amino acids and derivatives that absorb moisture. Barrier disruption has been shown to differentially affect the levels of specific NMF components, though the kinetics of NMF component restoration following disruption have not been examined. Here, we investigated the impact of barrier disruption caused by surfactant exposure on a subset of NMF components immediately following exposure and out to 10 days post-exposure., Methods: Volunteers wore patches containing either 1% w/v sodium lauryl sulphate (SLS) or distilled water on their forearms for 24 h. Measurements of transepidermal water loss, erythema, SC water content and a subset of SC NMF and lipid components were obtained at both sites before treatment, the day of patch removal, and 1, 2, 3, 6, and 10 days following treatment., Results: Most measured NMF components decreased in response to SLS exposure. Exceptions were increases in lactate, ornithine and urea, and no difference in proline levels. In the days following exposure, reduced levels of several NMF components continued at the SLS site; however, all measured NMF components demonstrated equivalence to the vehicle control within 10 days. Histidine pH 7, lactate, ornithine and urea were the first to achieve levels equivalent to the vehicle control site, normalizing within 1 day after patch removal., Conclusion: Results imply that NMF components derived from sweat and urea cycling are least impacted by SLS exposure whereas NMF components derived from degradation of filaggrin and/or other S-100 proteins are most impacted. This implies the restoration of the processes responsible for S-100 protein processing into free amino acids takes several days to return to normal. Further examination of the enzymes involved in S-100 protein processing following barrier disruption would provide insight into the pathway(s) for NMF restoration during SC recovery., (© 2013 Society of Cosmetic Scientists and the Société Française de Cosmétologie.)

Although barrier function of psoriatic skin is shown to be decreased by measuring transepidermal water loss (TEWL), few reports exist examining other physical skin properties and components including stratum corneum hydration, natural moisturizing factor (NMF), free fatty acids (FFA), β-sheet and α-helix ratio of structural protein(s), and sebum content. We compared the skin properties and components of normal, involved and uninvolved skin of psoriasis. Using a corneometer and attenuated total reflection-infrared spectrometer, we measured TEWL, stratum corneum hydration, NMF, FFA, β/α ratio and sebum in psoriasis vulgaris patients and healthy controls. TEWL and β/α ratio of involved psoriatic skin were significantly increased compared with uninvolved skin and normal control skin. In contrast, stratum corneum hydration, NMF and FFA, but not sebum, are significantly decreased in the involved skin compared with uninvolved skin and normal skin. TEWL and stratum corneum hydration returned to the normal levels following clinical improvement of the lesion. Barrier function and hydration of psoriatic skin are defective and secondary structure in stratum corneum protein is altered in the involved psoriatic skin., (© 2014 Japanese Dermatological Association.)

Background: Although physical properties of neonatal-infantile stratum corneum (SC) change drastically after birth, precise developmental alterations of specific sites have not been fully elucidated., Objective: To determine the longitudinal alterations of neonatal-infantile SC functions and components of upper thighs and diaper-covered buttocks during the first year of life. The data were compared with those of adults., Methods: Nineteen full-term neonates and their mothers were subjected to the measurements. Skin hydration, water sorption/retention capacity, TEWL were measured. Superficial SC analyses for NMF, ester binding sebum, and free fatty acids were performed by ATR-FTIR spectrometer. Total amount of ceramides (CERs) and CER subclasses were analyzed by NPLC-ESI-MS., Results: SC hydration of neonatal thighs was lower than that of their mothers, which rapidly increased during the 1st month. Skin hydration of neonatal buttocks was similar to that of their mothers. This also rapidly increased during the 1st month. The neonatal TEWL was less than those of their mothers indicating more efficient barrier function at both sites, which significantly increased during the 1st year development. This was mostly correlated decreased in the ω-hydroxy fatty acid-esterified CERs. Superficial ester-binding sebum content of neonates was similar to that of their mothers, which significantly decreased during the measurement; the decrease was more marked on buttocks. Neither NMF nor FFA of the superficial SC showed significant alteration during the 1-year development., Conclusion: Our results indicate that physical functions and components of neonatal-infantile SC show considerable alterations between diaper-covered buttocks and upper thighs during the 1st year development., (Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

Background: Amino acids (AAs) play important roles in maintaining an optimal hydration state of stratum corneum (SC) as a natural moisturizing factor (NMF). Recently, however, we have reported that lactate and potassium significantly affect the hydration state of SC., Objective: To explore the source of lactate and potassium in SC, we compared the concentration of various NMFs such as AAs, pyrrolidone carbonic acid (PCA), lactate, sodium, and potassium in SC between anhidrotic and adjacent hidrotic areas of patients with acquired idiopathic generalized anhidrosis or segmental anhidrosis., Methods: We examined 13 anhidrotic areas and the adjacent hidrotic skin of 10 different patients. We first determined anhidrotic and hidrotic areas of each patient by the iodine starch method and examined the hydration state of SC by measuring the high-frequency conductance. Then we obtained SC by tape stripping and measured the content of AAs, PCA, lactate, urea, sodium, and potassium in SC obtained from the anhidrotic and hidrotic areas. We examined the effect of increased insensible perspiration on the SC hydration and the concentrations of NMFs., Results: The SC of anhidrotic areas showed significantly low hydration. Among NMFs, lactate, urea, sodium, and potassium were significantly decreased in the SC of anhidrotic areas, while AAs and PCA were not significantly different between hidrotic and anhidrotic areas. Increased insensible perspiration increased SC hydration as well as NMFs other than AAs and PCA., Conclusion: Sweat constitutes lactate, urea, sodium, and potassium in NMFs and plays a crucial role in maintaining the physiological hydration state of SC., (Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)