Relationship Between NMF (Lactate and Potassium) Content and the Physical Properties of the Stratum Corneum in Healthy Subjects

Ionic composition of Shotokuseki extract alters cell differentiation and lipid metabolism in three-dimensional cultured human epidermis

Corneocytes and intercellular lipids form the stratum corneum. The content and composition of intercellular lipids in the stratum corneum significantly affect skin barrier function. The purpose of this study was to demonstrate the effect of Shotokuseki extract (SE) on intercellular lipid production and metabolism in human three-dimensional cultured human epidermis. SE or ion mixtures containing five common ions were applied to three-dimensional cultured human epidermis for 2-8 days for each assay. The mRNA expression levels of epidermal differentiation markers and lipid metabolism genes were quantified by real-time PCR. After extraction of lipids from the epidermis, ceramide, sphingosine, free fatty acids, and cholesterol were quantified by LC-MS/MS, GC-MS, or HPLC. The results showed that the application of SE increased the gene expression levels of epidermal differentiation markers keratin10 and transglutaminase. Elongation of very long-chain fatty acids protein 3, serine palmitoyl transferase, ceramide synthase 3, and acid ceramidase mRNA expression levels increased and fatty acid synthase mRNA expression decreased. The content of each lipid, [EOS] ceramide decreased and total sphingosine content increased on day 4. On day 8 of application, ceramide [NDS], [NP], and [EODS] increased and total free fatty acid content decreased. These results show that SE alters the lipid composition of the epidermis, increasing ceramides and decreasing free fatty acids in the epidermis. The composition of the ions in the SE may be responsible for the changes in lipid composition. These behaviors were different from those observed when the ion mixture was applied.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00616-3.

Characterization of skin barrier defects using infrared spectroscopy in patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is characterized by skin barrier defects that are often measured by biophysical tools that observe the functional properties of the stratum corneum (SC).

OBJECTIVES

To employ in vivo infrared spectroscopy alongside biophysical measurements to analyse changes in the chemical composition of the SC in relation to AD severity.

METHODS

We conducted an observational cross-sectional cohort study where attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy measurements were collected on the forearm alongside surface pH, capacitance, erythema and transepidermal water loss (TEWL), combined with tape stripping, in a cohort of 75 participants (55 patients with AD stratified by phenotypic severity and 20 healthy controls). Common FLG variant alleles were genotyped.

RESULTS

Reduced hydration, elevated TEWL and redness were all associated with greater AD severity. Spectral analysis showed a reduction in 1465 cm-1 (full width half maximum) and 1340 cm-1 peak areas, indicative of less orthorhombic lipid ordering and reduced carboxylate functional groups, which correlated with clinical severity (lipid structure r = -0.59, carboxylate peak area r = -0.50).

CONCLUSIONS

ATR-FTIR spectroscopy is a suitable tool for the characterization of structural skin barrier defects in AD and has potential as a clinical tool for directing individual treatment based on chemical structural deficiencies.

A missense mutation (rs209302038) of KRT9 gene associated with heat stress in Chinese cattle

Type I keratin 9 encoded by the KRT9 gene serves an important special function either in the mature palmar and plantar skin tissue. The changes in skin conditions and thickening of the outer layer of the skin may be affected by environmental variables. A missense mutation rs209302038 (NC_037346.1: g.41782870 G > A) was detected in KRT9, which changing the isoleucine into valine. This study aimed to identify the frequency of allele in this locus in Chinese indigenous cattle, and analyze the connection with heat stress. Our results indicated that the frequency of allele A gradually decreases from south to north, while the frequency of G allele showed the opposite pattern. Further analysis of the association of the different genotypes with three climate factors, which showed that the genotypes (GG, GA, AA) were significantly related to climatic conditions (p < 0.01). Therefore, we speculated that the mutation of the rs209302038 in Chinese indigenous cattle might be a genetic marker to detect heat stress.

β-1,4-Galactan suppresses lipid synthesis in sebaceous gland cells via TLR4

Sebum is a lipid mixture secreted from sebaceous glands of the skin. The excessive secretion of sebum causes acne vulgaris and seborrheic dermatitis, while its deficiency causes xerosis. Therefore, the appropriate control of sebum secretion is crucially important to keep the skin healthy. In the present study, we evaluated the effects of naturally occurring polysaccharides on lipid biosynthesis in hamster sebaceous gland cells. Among the tested polysaccharides, β-1,4-galactan, the main chain of type I arabinogalactan, most potently suppressed lipid synthesis in the sebaceous gland cells as analysed by oil red O staining. Toll-like receptor (TLR)4 inhibitors counteracted this suppressive effect and lipopolysaccharide, a TLR4 ligand, mimicked this effect, suggesting the involvement of the TLR4 signalling pathway. In the cells β-1,4-galactan significantly decreased mRNA levels of lipogenesis-related transcription factors (peroxisomeGraphical Abstract$\includegraphics{\bwartpath }$ proliferator-activated receptor γ and sterol regulatory element-binding protein 1) and enzymes (acetyl-CoA carboxylase and fatty acid synthase) as well as the glucose transporter GLUT4. Furthermore, β-1,4-galactan increased the production of lactic acid serving as a natural moisturizing factor and enhanced the proliferation of sebaceous gland cells. These results suggest potential of β-1,4-galactan as a material with therapeutic and cosmetic values for the skin.

The Impact of Diclofenac Gel on Ion Transport in the Rabbit (Oryctolagus cuniculus) Skin: An In Vitro Study

Diclofenac belongs to the non-steroidal anti-inflammatory drugs with analgesic, antipyretic and anti-inflammatory effects. Diclofenac administration on the skin may be associated with the appearance of side effects. The study aimed to evaluate the impact of diclofenac gel on transepithelial electrophysiological parameters of the 55 rabbit abdomen skin specimens. The electric parameters were analyzed in a modified Ussing chamber. The resistance (R) of the skin specimens treated with diclofenac gel significantly increased, which could be related to the reduction in the water content in intercellular spaces and, consequently, tighter adhesion of the cells. Increased electric potential (PD) was also observed in the skin specimens treated with diclofenac gel. The increase in both R and PD measured under stationary conditions was most likely caused by a transient and reversible increase in sodium ion transport, as the R and PD values decreased after the diclofenac gel was washed away. However, diclofenac gel did not affect the maximum and minimum PDs measured during stimulations. Therefore, it seems that diclofenac gel does not affect the perception of stimuli in the model system used.

Skin hydration measurement and the prediction of the early development of pressure ulcers among at risk adults: A systematic review

This systematic review aimed to examine skin hydration and determine if this biophysical parameter can predict pressure ulcer development in at risk adults. A literature search was conducted in March 2022, using PubMed, CINAHL, SCOPUS, Cochrane, and EMBASE databases. A total of 1727 records were returned, with 9 studies satisfying the inclusion criteria. Data were extracted using a pre-designed extraction tool and a narrative synthesis of the data was undertaken. The methodological quality of the included articles was assessed using the evidence-based librarianship checklist. Included studies were published between 1997 and 2021, with most using a prospective cohort design (88.9%, n = 8). The mean sample size was 74 participants (SD = 38.6; median 71). All studies measured skin hydration objectively, with 55.6% (n = 5) using the Corneometer® CM825 and 33.3% (n = 3) of studies reported a statistically significant association between skin hydration and pressure ulcer development. The mean evidence-based librarianship percentage was 66.6% (SD: 20.7%), however, only 33.3% (n = 3) of studies scored ≥75%, indicating validity. The quality of included studies, methodology variation, and reported results has reduced the homogeneity of outcomes. This review highlights the requirement for future research evidence to ascertain the role of skin hydration in pressure ulcer development.

Moisturizer in Patients with Inflammatory Skin Diseases

As interest in skin increases, the cosmetic market is also growing. It is difficult to choose between the numerous types of basic cosmetics on the market. This article aims to provide advice and guidance on which products to recommend according to a patient’s skin condition. Appropriate application of a moisturizer attempts not only to improve the dryness, but also improve the skin’s natural barrier function to protect the skin from internal and external irritants to keep the skin healthy. Moisturizers consist of various ingredients, including occlusive agents, emollients, humectants, lipid mixture, emulsifiers, and preservatives. Pathophysiology of dry skin is also discussed to provide readers with the background they need to choose the right moisturizer for themselves. As moisturizers play an important role as adjuvant in the treatment of common skin diseases, such as atopic dermatitis, contact dermatitis, psoriasis, acne and rosacea, which type of moisturizer is appropriate for each disease was also dealt with. Basic cosmetics, especially moisturizers, should be recommended in consideration of the ingredients, effectiveness and safety of each product, and the skin condition of each patient.

Mechanisms and Implications of Bacterial Invasion across the Human Skin Barrier

Atopic dermatitis (AD) is associated with a deficiency of skin lipids, increased populations of Staphylococcus aureus in the microbiome, and structural defects in the stratum corneum (SC), the outermost layer of human skin. However, the pathogenesis of AD is ambiguous, as it is unclear whether observed changes are the result of AD or contribute to the pathogenesis of the disease. Previous studies have shown that S. aureus is capable of permeating across isolated human SC tissue when lipids are depleted to levels consistent with AD conditions. In this study, we expand upon this discovery to determine the mechanisms and implications of bacterial penetration into the SC barrier. Specifically, we establish if bacteria are permeating intercellularly or employing a combination of both inter- and intracellular travel. The mechanical implications of bacterial invasion, lipid depletion, and media immersion are also evaluated using a newly developed, physiologically relevant, temperature-controlled drip chamber. Results reveal for the first time that S. aureus can be internalized by corneocytes, indicating transcellular movement through the tissue during permeation, consistent with previous theoretical models. S. aureus also degrades the mechanical integrity of human SC, particularly when the tissue is partially depleted of lipids. These observed mechanical changes are likely the cause of broken or ruptured tissue seen as exudative lesions in AD flares. This work further highlights the necessity of lipids in skin microbial barrier function.

IMPORTANCE Millions of people suffer from the chronic inflammatory skin disease atopic dermatitis (AD), whose symptoms are associated with a deficiency of skin lipids that exhibit antimicrobial functions and increased populations of the opportunistic pathogen Staphylococcus aureus. However, the pathogenesis of AD is ambiguous, and it remains unclear if these observed changes are merely the result of AD or contribute to the pathogenesis of the disease. In this article, we demonstrate the necessity of skin lipids in preventing S. aureus from penetrating the outermost barrier of human skin, thereby causing a degradation in tissue integrity. This bacterial permeation into the viable epidermis could act as an inflammatory trigger of the disease. When coupled with delipidated AD tissue conditions, bacterial permeation can also explain increased tissue fragility, potentially causing lesion formation in AD patients that results in further enhancing bacterial permeability across the stratum corneum and the development of chronic conditions.

Skin pH varies among bat species and seasons and between wild and captive bats

Skin is a key aspect of the immune system in the defence against pathogens. Skin pH regulates the activity of enzymes produced both by hosts and by microbes on host skin, thus implicating pH in disease susceptibility. Skin pH varies inter- and intra-specifically and is influenced by a variety of intrinsic and extrinsic variables. Increased skin alkalinity is associated with a predisposition to cutaneous infections in humans and dogs, and inter-specific and inter-individual variation in skin pH is implicated in differential susceptibility to some skin diseases. The cutaneous pH of bats has not been characterized but is postulated to play a role in susceptibility to white-nose syndrome (WNS), a fungal infection that has decimated several Nearctic bat species. We used non-invasive probes to measure the pH of bat flight membranes in five species with differing susceptibility to WNS. Skin pH ranged from 4.67 to 8.59 and varied among bat species, geographic locations, body parts, age classes, sexes and seasons. Wild Eptesicus fuscus were consistently more acidic than wild Myotis lucifugus, Myotis leibii and Perimyotis subflavus. Juvenile bats had more acidic skin than adults during maternity season but did not differ during swarming. Male M. lucifugus were more acidic than females during maternity season, yet this trend reversed during swarming. Bat skin was more acidic in summer compared to winter, a pattern also reported in humans. Skin pH was more acidic in captive than wild E. fuscus, suggesting environmental impacts on skin pH. The pH of roosting substrates affects skin pH in captive bats and may partially explain seasonal patterns in wild bats that use different roost types across seasons. Future research on the influence of pH on microbial pathogenic factors and skin barrier function may provide valuable insights on new therapeutic targets for treating bat skin conditions.

Seasonal changes in the physiological features of healthy and sensitive skin

BACKGROUND

The effects of seasonal factors on sensitive skin (SS) have been reported intensively, but the mechanisms still remain poorly understood.

OBJECTIVE

To investigate the effects of seasonal factors on SS, by comparing the physiological changes in the healthy skin and different subgroups of SS with seasonal variation.

METHODS

Through a questionnaire survey, lactic acid sting test, and capsaicin test, qualified subjects were classified into four groups: healthy skin, only lactic acid sting test positive (LAST(+)/CAT(-)), only capsaicin test positive (LAST(-)/CAT(+)), and both positive (LAST(+)/CAT(+)). Skin physiological parameters were measured in winter and summer.

RESULTS

A total of 140 subjects completed the study. Significant differences were found in transepidermal water loss (TEWL), skin pH, and cutaneous blood flow (CBF) between winter and summer in the four groups. There were significant differences in stratum corneum hydration (SCH) of the LAST(+)/CAP(-) and LAST(+)/CAP(+) groups, current perception threshold (CPT) at 250 Hz of the LAST(+)/CAT(+) group, and epidermal density of the healthy skin group between the two seasons. Sum of the scores of sting (SSS) showed a close correlation with TEWL, SCH, pH, CPT at 250 Hz, and epidermal density. Sum of the scores of burning (SSB) showed a strong correlation with TEWL, pH, CPT at 250 Hz and 5 Hz, and epidermal density.

CONCLUSIONS

Seasonal variation influences the skin barrier function of different types of sensitive skin at different levels. We therefore strongly suggest that, with seasonal variation, different treatments will be undertaken for different subgroups of sensitive skin.

The influence of hydration status on ion transport in the rabbit (Oryctolagus cuniculus) skin-An in vitro study

The preservation of physiological transport of ions and water content is particularly important for maintaining the skin barrier, touch and pain stimuli, as well as the initiation of skin regeneration processes, especially after treatments associated with breaking skin continuity and wound healing difficulties. The aim of the study was to assess changes in ion transport, measured as values of transepithelial electric resistance and potential difference in stationary conditions and during mechanical-chemical stimulations, depending on the hydration status of isolated rabbit skin specimens. The specimens were divided into five groups: control (n = 22), dehydrated in 10% NaCl (n = 30), rehydrated after dehydration (n = 26), dried at 37°C (n = 26), and rehydrated after drying (n = 25). Dehydrated tissue samples showed altered resistance compared to the control; this change was maintained regardless of rehydration. In the dehydrated samples, changes in the measured electric potential were also noted, which returned to values comparable with the control after rehydration. Dehydrated skin, regardless of the cause of dehydration, responds with changes in the transport of sodium and chloride ions and the altered cellular microenvironment. It could influence the perception of stimuli, particularly pain, and slow down the regeneration processes.

Filaggrin-gene mutation has minimal effect on the disease severity in the lesions of atopic dermatitis

Loss-of-function mutations of filaggrin (FLG) gene (FLG) are the strongest known genetic risk factor for atopic dermatitis (AD). It is still debatable how FLG gene mutations and the resulting abnormal amount of FLG protein contribute to skin barrier function and symptoms of AD. In this study, we examined the effects of loss-of-function mutations of FLG gene on the severity of skin lesions and skin barrier function in 55 patients with AD by evaluating eight patients with AD with FLG gene mutations and 47 patients with AD without mutations. The results showed that the FLG gene mutation did not affect the duration of AD, severity of AD, degree of local inflammatory symptoms, skin water content and trans-epidermal water loss of the lesions. Next, in these eight mutation carriers and the 47 non-carriers, stratum corneum was collected from the three site of skin lesions using tape-stripping method, and the amounts of FLG protein and total amino acid contained in the stratum corneum was measured to investigate the effect of the FLG gene mutation on the amount of FLG gene product in the local lesion. FLG abnormalities had little effect on FLG protein and total amino acid content in the stratum corneum in the lesional skin. The amount of the FLG products, especially amino acids derived from FLG, in the stratum corneum of AD lesional skin is influenced by development of dermatitis. The results obtained from this study supports that the activation of Th2-dominant inflammatory cells, together with FLG abnormality, plays a role in suppressing the production of FLG in skin lesions.

Extraction of natural moisturizing factor from the stratum corneum and its implication on skin molecular mobility

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.

The stratum corneum water content and natural moisturization factor composition evolve with age and depend on body site

BACKGROUND

The study objective was to examine if age and chronic environmental exposure affect the water content and the composition of the natural moisturizing factors (NMFs) of the stratum corneum (SC).

METHODS

Forty healthy Caucasian women 18-70 years of age were recruited. Measurements were done on the cheek and on two skin sites on the arm (one relatively protected and one exposed to environmental factors). SC water content and NMF composition were measured by Raman confocal microspectroscopy.

RESULTS

The SC water content was gradually reduced with age, reaching statistically significant levels only on the exposed arm site. The SC water content remained higher on the face than on the two arm sites throughout the ages tested. The age-dependent concentration changes of various amino acids were species-specific, potentially indicating different protein sources. Interestingly, on the arm sites, the sum of decreasing amino acid concentrations is compensated by the sum of those increasing, resulting in constant total amino acid content. However, on the face, the total amino acid content statistically increased with age potentially relating to the declining cell turnover rates. The lactate content was higher on the face for all ages and statistically decreased on both arm sites.

CONCLUSION

Both chronological aging and chronic exposure to environmental factors mildly affect SC hydration, while they have variable effects in the concentrations of NMF components. The dynamics of NMF composition may at least partially explain the age-related changes in SC hydration.

Prebiotic Colloidal Oat Supports the Growth of Cutaneous Commensal Bacteria Including S. epidermidis and Enhances the Production of Lactic Acid

Background

Multiple skin conditions have been associated with alterations in the diversity and composition of the skin microbiome, including dry skin and atopic dermatitis. In these conditions, a number of commensal skin bacteria have been implicated in supporting a healthy skin barrier, including Staphylococcus epidermidis. Recent clinical studies in patients with mild-to-moderate atopic dermatitis and dry/itchy skin have shown significantly improved skin barrier function and microbial diversity upon treatment with moisturizers containing 1% colloidal oat. We hypothesized that direct use of colloidal oat by skin microbes contributes to these therapeutic benefits.

Methods

Skin bacterial growth was assessed using the BacT/ALERT system. Staphylococcus aureus and S. epidermidis growth rates and metabolism were compared in an in vitro competition assay. The effect of a 1% colloidal oat-containing moisturizer on lactic acid content of the stratum corneum was clinically assessed in subjects with moderate-to-severe dry skin. S. epidermidis gene expression was evaluated by next-generation mRNA sequencing. Short-chain fatty acids were quantified in bacterial culture supernatants.

Results

In vitro, colloidal oat increased the growth rate of S. epidermidis vs S. aureus, as well as the metabolism of S. epidermidis. Colloidal oat also significantly increased lactic acid concentrations in supernatants of both strains and decreased pH, consistent with clinical findings that 6-week use of a 1% colloidal oat-containing lotion significantly increased lactic acid on dry skin. Further analyses suggest that colloidal oat alters the gene expression profile of S. epidermidis.

Conclusion

Colloidal oat directly affects the growth, metabolism, lactic acid production, and gene expression of skin commensal bacteria, as shown via in vitro studies. The increased production of lactic acid reflects clinical observations with colloidal oat-containing skin moisturizers. Our findings suggest a new mechanism for colloidal oat as a skin prebiotic, which may contribute to improvements in skin and microbiome diversity in various skin conditions, including dry/itchy skin and atopic dermatitis.

Seasonal variations in the skin parameters of Caucasian women from Central Europe

BACKGROUND

The human skin is greatly affected by external factors such as UV radiation (UVR), ambient temperature (T), and air humidity. These factors oscillate during the year giving rise to the seasonal variations in the skin properties. The aim of this study was to evaluate the effect of seasons, environmental T, relative and absolute humidity on the skin parameters of Caucasian women, perform a literature review and discuss the possible factors lying behind the found changes.

MATERIALS AND METHODS

We measured stratum corneum (SC) hydration, transepidermal water loss (TEWL), sebum level, erythema index, and elasticity parameters R2 and R7 on the forehead and the cheek of Caucasian women from the Czech Republic throughout the year. We also performed a non-systematic literature review focused on the seasonal variations in these skin parameters.

RESULTS

We confirmed a well-documented low SC hydration and sebum production in winter. In spring, we found the lowest TEWL (on the forehead) and the highest SC hydration but also the highest erythema index and the lowest elasticity presumably indicating skin photodamage. For most of the skin parameters, the seasonal variations probably arise due to a complex action of different factors as we extensively discussed.

CONCLUSION

The data about the seasonal variations in the skin parameters are still highly inconsistent and further studies are needed for better understanding of the normal skin changes throughout the year.

Tape stripping method is useful for the quantification of antimicrobial peptides on the human skin surface including the stratum corneum

Antimicrobial peptides (AMPs) play an important role in innate immunity in human skin. It is known that AMPs mainly function in the stratum corneum. Therefore, AMP concentrations in the stratum corneum need to be precisely measured to clarify functional and physiological importance of AMPs in cutaneous defence. Tape stripping (TS) is a well-established method by which components in the stratum corneum can be collected. However, the usefulness of the TS method for measuring AMP concentration in human skin remains unclear. Therefore, we compared it with another popular method, skin rinsing, which had been established as a method for measuring AMP concentration in human skin. When investigated on healthy medial forearm using RNase 7, which is one of the typical AMPs, as an index, there was a significant positive correlation between RNase 7 concentrations measured by the TS method at adjacent forearm sites, demonstrating the reproducibility of the TS method. Next, a significant positive correlation was detected in RNase 7 concentrations measured using the TS and the skin rinsing method, indicating that the TS method is comparable to the skin rinsing method. Thus, we speculate that the TS method is useful for measuring AMP concentration in human skin.

Noninvasive Epidermal Metabolite Profiling

A buffer placed in brief contact in the skin was assayed by ¹H NMR spectroscopy. We found that this passive extraction of the skin surface yields abundant metabolites. Metabolites of the skin surface originate from a variety of sources, including the sweat gland, which produces lactate from the glucose received from its capillary bed. Little is known about how metabolites resident on and within the skin surface respond to a metabolic or hemodynamic perturbation. As a possible application of epidermal metabolite profiling, we asked whether metabolites extracted from the skin surface are indicative of heart failure. The levels of lactate and other molecules were significantly lower in patients in heart failure than in individuals who reported healthy heart function, possibly due to reduced blood flow to the sweat gland resulting in a lack of tissue perfusion. Most amino acids were unchanged in levels, except for glycine and serine that increased as a percentage of all amino acids. These results have the potential in the long term to help decide the extent to which a patient has heart failure for which objective measures are lacking. Moreover, the results suggest that epidermal metabolite profiling may be useful for other assessments of human health.

Indoor acids and bases

Numerous acids and bases influence indoor air quality. The most abundant of these species are CO₂ (acidic) and NH₃ (basic), both emitted by building occupants. Other prominent inorganic acids are HNO₃ , HONO, SO₂ , H₂ SO₄ , HCl, and HOCl. Prominent organic acids include formic, acetic, and lactic; nicotine is a noteworthy organic base. Sources of N-, S-, and Cl-containing acids can include ventilation from outdoors, indoor combustion, consumer product use, and chemical reactions. Organic acids are commonly more abundant indoors than outdoors, with indoor sources including occupants, wood, and cooking. Beyond NH₃ and nicotine, other noteworthy bases include inorganic and organic amines. Acids and bases partition indoors among the gas-phase, airborne particles, bulk water, and surfaces; relevant thermodynamic parameters governing the partitioning are the acid-dissociation constant (K_a ), Henry's law constant (K_H ), and the octanol-air partition coefficient (K_oa ). Condensed-phase water strongly influences the fate of indoor acids and bases and is also a medium for chemical interactions. Indoor surfaces can be large reservoirs of acids and bases. This extensive review of the state of knowledge establishes a foundation for future inquiry to better understand how acids and bases influence the suitability of indoor environments for occupants, cultural artifacts, and sensitive equipment.

Effects of lactic acid on the flexibility of the stratum corneum

BACKGROUND

Lactic acid increases the flexibility of the stratum corneum by linking directly to keratin without water. However, another study reported the involvement of water. This study aimed to clarify how lactic acid contributes to the flexibility of the stratum corneum (SC) of the face.

MATERIALS AND METHODS

A tactile sensor was used to measure the change in shared frequency (Δf) in the cheeks of 88 women of various ages. Amounts of water and lactic acid in the SC were measured during all four seasons, and correlations with Δf evaluated.

RESULTS

Lactic acid and water levels in the SC were not correlated in any season. In the younger subjects only, the lactic acid content correlated with Δf in spring (when at its highest level in the SC), whereas the water content correlated with Δf in summer and autumn (when the water content was high).

CONCLUSIONS

The overall lack of correlations between lactic acid and water content across all ages and seasons suggested that each contributes independently to the flexibility of the SC and that lactic acid softens the SC without water.

Phycocosmetics and Other Marine Cosmetics, Specific Cosmetics Formulated Using Marine Resources

Marine resources exist in vast numbers and show enormous diversity. As a result, there are likely many possible applications for marine molecules of interest in the cosmetic industry, whether as excipients or additives, but especially as active substances. It is possible to obtain extracts from active substances; for example, quite a few algae species can be used in moisturizing or anti-ageing products. In the field of topical photoprotection, mycosporine-like amino acids and gadusol are important lines of enquiry that should not be overlooked. In the field of additives, the demonstration that certain seaweed (algae) extracts have antimicrobial properties suggests that they could provide alternatives to currently authorized preservatives. These promising leads must be explored, but it should be kept in mind that it is a long process to bring ingredients to market that are both effective and safe to use.

Seasonal variations of epidermal biophysical properties in Kunming, China: A self-controlled cohort study

BACKGROUND

Epidermal biophysical properties can be affected by many factors, including body site, age, gender, ethnicity, disease, temperature, humidity, and ultraviolet (UV) radiation. Information about variation of epidermal biophysical properties with seasons is still limited. In the present study, we determined seasonal variation of epidermal biophysical properties of women in Kunming, China.

MATERIALS AND METHODS

A total of 72 women, aged 22.96 ± 2.11 years, were enrolled in this study. Transepidermal water loss rates (TEWL), stratum corneum (SC) hydration, sebum content, melanin index (MI), erythema index (EI), and L*a* values were measured on the right cheek and the right forearm, using a non-invasive skin physiological instrument in the spring, summer, autumn, and winter in Kunming, China.

RESULTS

On the cheek, TEWL, SC hydration, sebum, MI, and L*a* values varied greatly with seasons (P < .05). SC hydration, sebum, MI, and a*value peaked in the summer, but went lowest in winter. In contrast, TEWL and L*value went lowest in summer but peaked in winter. Similarly, SC hydration, MI, and L*value also varied with seasons on the forearm (P < .05). In addition, SC hydration, sebum, MI, EI, and a*value of the cheek were higher than that of the forearm (P < .001), but L*values of the cheek were lower than that of the forearm (P < .001). There were no correlations among TEWL and MI, EI, and L*a*values in any season (P > .05).

CONCLUSIONS

Both epidermal permeability barrier function, sebum, and skin pigment in healthy women vary seasons in Kunming, China.

Novel petrolatum-based ointment that is highly moisturizing and has superior usability with increased adherence in patients with facial dry skin

BACKGROUND

Petrolatum is often used to suppress water evaporation from the skin surface. However, its stickiness, shininess, and other factors make it inconvenient for continuous use.

OBJECTIVE

To compare the effectiveness and usability between a newly developed petrolatum-based ointment (NOV^® II Moisture Balm) and white petrolatum.

METHODS

Twenty-nine subjects with atopic dermatitis or xeroderma with symptoms of dry skin applied NOV^® II Moisture Balm on the right sides of the face and white petrolatum on the left side, respectively, for 8-12 weeks. The skin conditions (erythema, exudate/crusting, dryness, and itch) were scored, stratum corneum water content and transepidermal water loss (TEWL) were measured, and the free amino acid and thymic stromal lymphopoietin (TSLP) levels in the stratum corneum were analyzed before and end of the trial.

RESULTS

Dryness, exudate/crusting, and TEWL decreased significantly on both the white petrolatum and the NOV^® II Moisture Balm sides, while stratum corneum water content and the free amino acid levels in the stratum corneum increased significantly. On the NOV^® II Moisture Balm side, erythema and the TSLP levels decreased significantly. In a questionnaire on usability, the subjects felt NOV^® II Moisture Balm spread better and were less sticky and shiny than white petrolatum, and more subjects wanted to continue using NOV^® II Moisture Balm.

CONCLUSIONS

NOV^® II Moisture Balm was equivalent to white petrolatum in moisturizing and improving the physiologic functions of the skin, but had superior usability.

The molecular clock in the skin, its functionality, and how it is disrupted in cutaneous melanoma: a new pharmacological target?

The skin is the interface between the organism and the external environment, acting as its first barrier. Thus, this organ is constantly challenged by physical stimuli such as UV and infrared radiation, visible light, and temperature as well as chemicals and pathogens. To counteract the deleterious effects of the above-mentioned stimuli, the skin has complex defense mechanisms such as: immune and neuroendocrine systems; shedding of epidermal squamous layers and apoptosis of damaged cells; DNA repair; and pigmentary system. Here we have reviewed the current knowledge regarding which stimuli affect the molecular clock of the skin, the consequences to skin-related biological processes and, based on such knowledge, we suggest some therapeutic targets. We also explored the recent advances regarding the molecular clock disruption in melanoma, its impact on the carcinogenic process, and its therapeutic value in melanoma treatment.

Basket-weave structure in the stratum corneum is an important factor for maintaining the physiological properties of human skin as studied using reconstructed human epidermis and tape stripping of human cheek skin

BACKGROUND

The normal stratum corneum (SC) has an upper basket-weave (BW) pattern layer and a lower compact layer. The transition from compact to BW SC is well associated with a transition from diffuse to peripheral distributions of corneodesmosomes (CDs). The loss of transition from compact SC to BW SC appears to cause structural and barrier-function impairments.

OBJECTIVES

To show the involvement of the BW SC in maintaining the physiological properties of the skin.

METHODS

Reconstructed human epidermis (RHE) with a complete BW structure was created by treatment with prepared emulsion-A, an oil-in-water emulsion. The RHE tissues were subjected to histological analysis, and the distribution of CDs on the SC with or without BW SC was analysed by anti-desmoglein (Dsg)1 antibody immunofluorescence and ultrastructural and Western blotting analyses. Ultrastructural analysis of intercellular lipids was performed. The mechanical properties of the RHE were evaluated.

RESULTS

Emulsion-A successfully generated the BW SC in the RHE in which the degradation of CDs was promoted. The intercellular space of the BW SC generated by emulsion-A was filled with multilamellar lipid sheets. The softness of the SC with a BW structure formed with emulsion-A was higher than that of the compact SC in RHE. The outermost SC Dsg1 degradation (formation of the BW SC as determined with Dsg1 pixels) was correlated with water-barrier functions and the SC softness of healthy human cheek, which varied widely.

CONCLUSIONS

Emulsion-A successfully generated the BW SC in RHE for the first time. This method is suggested to be a useful tool for investigating the physiological significance of the BW SC in vitro. Determination of Dsg1 content in the SC obtained by tape stripping from human skin allows study of the effects of external stimulants, such as creams and ointments, including cosmetics, on the completeness of the BW SC in situ without biopsy. What's already known about this topic? The normal stratum corneum (SC) has two layers, an upper basket-weave (BW) pattern layer and a lower compact layer. Epidermal diseases such as ichthyosis vulgaris and X-linked ichthyosis have an incomplete or no BW SC and impaired SC barrier functions, in which corneodesmosome (CD) degradation in a peripheral distribution is impaired. The roles of the BW SC in the physiological properties of human skin have not been clearly elucidated. What does this study add? Reconstructed human epidermis (RHE) with a complete BW structure was generated for the first time by treatment with oil-in-water emulsion-A. The formation of the BW SC was associated with a decrease in Dsg1 content, which represents the CD number in the SC. The intercellular space of the BW SC generated by emulsion-A, but not compact SC, was filled with multilamellar lipid sheets. The softness of the SC with a BW structure formed by emulsion-A treatment was higher than that of the compact SC in RHE. What is the translational message? RHE with a complete BW SC generated by emulsion-A treatment is suggested to be a useful tool for investigating effects on the physiological functions of the BW SC, as in treatments with creams and ointments including cosmetics. Determination of desmoglein 1 content in the SC obtained by tape stripping from human skin can make it possible to study the effects of external stimulants, such as creams and ointments, including cosmetics, on the completeness of the BW SC in situ without biopsy.

Orally Administered Polysaccharide Derived from Blackcurrants (Ribes nigrum L.) Improves Skin Hydration in Ultraviolet-Irradiated Hairless Mice

Blackcurrants (Ribes nigrum L.) have various benefits for human health. In particular, a polysaccharide derived from blackcurrant was found to be an immunostimulating food ingredient in a mouse model. We named a polysaccharide derived from blackcurrant cassis polysaccharide (CAPS). In a previous clinical study, we reported that CAPS affects skin dehydration, demonstrating its effectiveness against skin inflammation was related to atopic dermatitis; skin inflammation caused skin dehydration. However, there are no studies regarding CAPS effectiveness against skin dehydration. The current study aimed to investigate CAPS effectiveness against skin dehydration. We further demonstrate the effect of oral administration of CAPS on skin dehydration caused by ultraviolet (UV) irradiation-induced inflammation in mice. We found that CAPS administration suppresses skin dehydration caused by UV irradiation. We also found that CAPS decreases interleukin-6 and matrix metalloproteinase transcription levels in the mouse skin. These results show that CAPS improves skin hydration in UV-irradiated mice.

Reconstructed Human Epidermis Predicts Barrier-Improving Effects of Lactococcus lactis Emulsion in Humans

BACKGROUND/AIMS

The skin provides protection against chemical, physical, and biological stressors, yet the skin morphology changes over the course of life. These changes might affect the skin barrier function and facilitate the onset of age-related diseases. Since orally applied lactic acid bacteria ameliorate signs of aged and atopic skin, we investigated the effects of a topically applied Lactococcus lactis emulsion.

METHODS

In a blinded, randomized, vehicle-controlled trial, we studied topical Lactococcus effects both in vitro and in 20 healthy female volunteers. Commercially available reconstructed human epidermis (RHE) was treated for 4 days (once daily) and volar forearms were treated for 30 days (twice daily).

RESULTS

Lactococcus formulations improve the skin barrier in RHE as shown by increased filaggrin and human β-defensin-2 expression as well as by the 23% declined mean apparent permeability coefficients for caffeine. A reduction of 18% in transepidermal water loss confirms this effect in humans. Moreover, Lactococcus emulsion optimized skin hydration and surface pH. Skin irritation was not detected.

CONCLUSIONS

Lactococcus emulsion improved the skin barrier function with good biocompatibility. Moreover, our study exemplifies the translational predictive capacity of testing on RHE with respect to Lactococcus emulsion.

Salt water and skin interactions: new lines of evidence

In Health Resort Medicine, both balneotherapy and thalassotherapy, salt waters and their peloids, or mud products are mainly used to treat rheumatic and skin disorders. These therapeutic agents act jointly via numerous mechanical, thermal, and chemical mechanisms. In this review, we examine a new mechanism of action specific to saline waters. When topically administered, this water rich in sodium and chloride penetrates the skin where it is able to modify cellular osmotic pressure and stimulate nerve receptors in the skin via cell membrane ion channels known as "Piezo" proteins. We describe several models of cutaneous adsorption/desorption and penetration of dissolved ions in mineral waters through the skin (osmosis and cell volume mechanisms in keratinocytes) and examine the role of these resources in stimulating cutaneous nerve receptors. The actions of salt mineral waters are mediated by a mechanism conditioned by the concentration and quality of their salts involving cellular osmosis-mediated activation/inhibition of cell apoptotic or necrotic processes. In turn, this osmotic mechanism modulates the recently described mechanosensitive piezoelectric channels.

Sweat from gland to skin surface: production, transport, and skin absorption

By combining galvanic skin conductance (GSC), stratum corneum hydration (HYD) and regional surface sweat rate (RSR) measurements at the arm, thigh, back and chest, we closely monitored the passage of sweat from gland to skin surface. Through a varied exercise-rest protocol, sweating was increased slowly and decreased in 16 male and female human participants (25.3 ± 4.7 yr, 174.6 ± 10.1 cm, 71.3 ± 12.0 kg, 53.0 ± 6.8 ml·kg^-1·min^-1). ∆GSC and HYD increased before RSR, indicating pre-secretory sweat gland activity and skin hydration. ∆GSC and HYD typically increased concomitantly during rest in a warm environment (30.1 ± 1.0°C, 30.0 ± 4.7% relative humidity) and only at the arm did ∆GSC increase before an increase in HYD. HYD increased before RSR, before sweat was visible on the skin, but not to full saturation, contradicting earlier hypotheses. Maximal skin hydration did occur, as demonstrated by a plateau in all regions. Post exercise rest resulted in a rapid decrease in HYD and RSR but a delayed decline in ∆GSC. Evidence for reabsorption of surface sweat into the skin following a decline in sweating, as hypothesized in the literature, was not found. This suggests that skin surface sweat, after sweating is decreased, may not diffuse back into the dermis, but is only evaporated. These data, showing distinctly different responses for the three measured variables, provide useful information about the fate of sweat from gland to surface that is relevant across numerous research fields (e.g., thermoregulation, dermatology, ergonomics and material design). NEW & NOTEWORTHY After sweat gland stimulation, sweat travels through the duct, penetrating the epidermis before appearing on the skin surface. We found that only submaximal stratum corneum hydration was required before surface sweating occurred. However, full hydration occurred only once sweat was on the surface. Once sweating reduces, surface sweat evaporation continues, but there is a delayed drying of the skin. This information is relevant across various research fields, including environmental ergonomics, dermatology, thermoregulation, and skin-interface interactions.

Skin care for healthy babies at term: A systematic review of the evidence

OBJECTIVES

to identify what skin practices are important for the protection of baby skin in healthy term babies (0-6 months) and generate evidence-based conclusions to inform health professionals and parents.

DESIGN

eleven databases were searched for all empirical quantitative and qualitative research published between 2000-2015 which explored baby skin care for bathing and cleansing, nappy care, hair and scalp care, management of dry skin or baby massage, for healthy term babies up to 6 months old. Papers not published in English were excluded. A total of 3062 papers were identified. Pairs of reviewers assessed all citations and extracted data independently. There were 26 included papers: 16 RCTs, 3 non-randomised experimental studies, 1 mixed-methods study and 6 qualitative studies. Primary and secondary outcome measures were analysed using meta-analysis or narrative descriptive statistics. Synthesis of qualitative data was not possible due to disparity of the evidence.

FINDINGS

from the small numbers of studies with comparable data, there was no evidence of any significant differences between tested wash products and water or tested baby wipes and water. There was some evidence to suggest that daily use of full-body emollient therapy may help to reduce the risk of atopic eczema in high risk babies with a genetic predisposition to eczema; however, the use of olive oil or sunflower oil for baby dry skin may adversely affect skin barrier function. There was no evidence about hair/scalp care or baby massage. Qualitative research indicates that parents and health professionals believe that water alone is best.

KEY CONCLUSIONS

meta-analysis was restricted due to the lack of consistency of study outcome measures. Although there is considerable RCT evidence comparing the use of specific products against water alone, or another product, for bathing, cleansing and nappy care, the power of this evidence is reduced due to inconsistency of outcome measures in terms of outcome, treatment site or time-point. The development of a core outcome measure set is advocated for trials assessing skin care practices.

IMPLICATIONS FOR PRACTICE

this review offers health professionals best evidence available on which to base their advice. Of those studies with comparative outcomes, the evidence indicates no difference between the specific products tested and water alone; offering parents a choice in their baby skin care regimen. Protocol available: http://www.crd.york.ac.uk/PROSPEROFILES/28054_PROTOCOL_20151009.pdf.

Coffee polyphenols extracted from green coffee beans improve skin properties and microcirculatory function

Coffee polyphenols (CPPs), including chlorogenic acid, exert various physiological activities. The purpose of this study was to investigate the effects of CPPs on skin properties and microcirculatory function in humans. In this double-blind, placebo-controlled study, 49 female subjects with mildly xerotic skin received either a test beverage containing CPPs (270 mg/100 mL/day) or a placebo beverage for 8 weeks. The ingestion of CPPs significantly lowered the clinical scores for skin dryness, decreased transepidermal water loss, skin surface pH, and increased stratum corneum hydration and the responsiveness of skin blood flow during local warming. Moreover, the amounts of free fatty acids and lactic acid in the stratum corneum significantly increased after the ingestion of CPPs. These results suggest that an 8-week intake of CPPs improve skin permeability barrier function and hydration, with a concomitant improvement in microcirculatory function, leading to efficacy in the alleviation of mildly xerotic skin.

Dual-stimuli responsive liposomes using pH- and temperature-sensitive polymers for controlled transdermal delivery

The use of skin environment-sensitive liposomes for transdermal penetration is beneficial for improving cosmetic efficacy.

Impaired Tight Junctions in Atopic Dermatitis Skin and in a Skin-Equivalent Model Treated with Interleukin-17

Tight junction (TJ) dysfunction in the stratum granulosum leads to aberrant barrier function of the stratum corneum (SC) in the epidermis. However, it is unclear whether TJs are perturbed in atopic dermatitis (AD), a representative aberrant SC-related skin disease, and whether some factors related to AD pathogenesis induce TJ dysfunction. To address these issues, we investigated the alterations of TJs in AD skin and the effects of Th2 and Th17 cytokines on TJs in a skin-equivalent model. The levels of TJ proteins were determined in the epidermis of nonlesional and lesional skin sites of AD. Western blot and immunohistochemical analyses revealed that the levels of zonula occludens 1 were decreased in the nonlesional sites of AD, and the levels of zonula occludens 1 and claudin-1 were decreased in the lesional sites relative to the levels in skin from healthy subjects. Next, we examined the effects of interleukin (IL)-4, tumor necrosis factor-α, IL-17, and IL-22 on the TJ barrier in a skin-equivalent model. Only IL-17 impaired the TJ barrier. Furthermore, we observed a defect in filaggrin monomer degradation in the IL-17-treated skin model. Thus, TJs are dysfunctional in AD, at least partly, due to the effect of IL-17, which may result in an aberrant SC barrier.

Design, synthesis and characterization of linear unnatural amino acids for skin moisturization

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.

Development of stratum corneum chymotrypsin-like protease activity and natural moisturizing factors from birth to 4 weeks of age compared with adults

BACKGROUND

From birth, the functional properties of the neonatal epidermal barrier mature whereby the stratum corneum (SC) hydrates and the skin surface acidifies. The identification of a thinner infant SC compared with adults suggests underdeveloped mechanisms underlying differentiation and desquamation.

OBJECTIVES

To assess the functional properties of the neonatal SC from birth, in conjunction with the quantification of superficial chymotrypsin-like protease activity [kallikrein-7 (KLK-7)] and filaggrin-derived natural moisturizing factors (NMF).

METHODS

A total of 115 neonates recruited to the Oil in Baby SkincaRE (OBSeRvE) randomized controlled trial underwent a full evaluation of the SC at birth (< 72 h old) and at 4 weeks of age (n = 39, no oil control group) using minimally invasive instrumentation and methodology. A cohort of 20 unrelated adults was recruited for comparison.

RESULTS

At birth NMF levels correlated with SC hydration (r = 0·50) and skin-surface pH (r = -0·54). From birth to 4 weeks, transepidermal water loss (TEWL), superficial KLK-7 activity and filaggrin-derived NMF significantly elevated. Impaired epidermal barrier function at birth (> 75th percentile TEWL) was accompanied by significantly elevated chymotrypsin-like protease activity and reduced levels of NMF.

CONCLUSIONS

The biophysical, biological and functional properties of the developing neonatal SC are transitional from birth to 4 weeks of age and differ significantly from adults. The presence of impaired barrier function with elevated protease activity and reduced NMF at birth suggests why certain infants are predisposed to epidermal barrier breakdown and the development of atopic dermatitis.

Understanding age-induced alterations to the biomechanical barrier function of human stratum corneum

BACKGROUND

The appearance and function of human skin are dramatically altered with aging, resulting in higher rates of severe xerosis and other skin complaints. The outermost layer of the epidermis, the stratum corneum (SC), is responsible for the biomechanical barrier function of skin and is also adversely transformed with age. With age the keratin filaments within the corneocytes are prone to crosslinking, the amount of intercellular lipids decreases resulting in fewer lipid bilayers, and the rate of corneocyte turnover decreases.

OBJECTIVES

The effect of these structural changes on the mechanical properties of the SC has not been determined. Here we determine how several aspects of the SC's mechanical properties are dramatically degraded with age.

METHODS

We performed a range of biomechanical experiments, including micro-tension, bulge, double cantilever beam, and substrate curvature testing on abdominal stratum corneum from cadaveric female donors ranging in age from 29 to 93 years old.

RESULTS

We found that the SC stiffens with age, indicating that the keratin fibers stiffen, similarly to collagen fibers in the dermis. The cellular cohesion also increases with age, a result of the altered intercellular lipid structure. The kinetics of water movement through the SC is also decreased.

CONCLUSIONS

Our results indicate that the combination of structural and mechanical property changes that occur with age are quite significant and may contribute to the prevalence of skin disorders among the elderly.

Effect of potassium present in stratum corneum during non-invasive measurement of potassium in human subjects using reverse iontophoresis

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.

Sebaceous gland, hair shaft, and epidermal barrier abnormalities in keratosis pilaris with and without filaggrin deficiency

Although keratosis pilaris (KP) is common, its etiopathogenesis remains unknown. KP is associated clinically with ichthyosis vulgaris and atopic dermatitis and molecular genetically with filaggrin-null mutations. In 20 KP patients and 20 matched controls, we assessed the filaggrin and claudin 1 genotypes, the phenotypes by dermatoscopy, and the morphology by light and transmission electron microscopy. Thirty-five percent of KP patients displayed filaggrin mutations, demonstrating that filaggrin mutations only partially account for the KP phenotype. Major histologic and dermatoscopic findings of KP were hyperkeratosis, hypergranulosis, mild T helper cell type 1-dominant lymphocytic inflammation, plugging of follicular orifices, striking absence of sebaceous glands, and hair shaft abnormalities in KP lesions but not in unaffected skin sites. Changes in barrier function and abnormal paracellular permeability were found in both interfollicular and follicular stratum corneum of lesional KP, which correlated ultrastructurally with impaired extracellular lamellar bilayer maturation and organization. All these features were independent of filaggrin genotype. Moreover, ultrastructure of corneodesmosomes and tight junctions appeared normal, immunohistochemistry for claudin 1 showed no reduction in protein amounts, and molecular analysis of claudin 1 was unremarkable. Our findings suggest that absence of sebaceous glands is an early step in KP pathogenesis, resulting in downstream hair shaft and epithelial barrier abnormalities.

Skin hydration in postmenopausal women: argan oil benefit with oral and/or topical use

The aim of this study

The aim of this study was to evaluate the effect of daily consumption and/or application of argan oil on skin hydration in postmenopausal women.

Material and methods

Sixty postmenopausal women consumed butter during the stabilization period and were randomly divided into two groups for the intervention period: the treatment group absorbed alimentary argan oil (n = 30) and the control group olive oil (n = 30). Both groups applied cosmetic argan oil in the left volar forearm during a sixty days’ period. Evaluation of skin hydration, i.e. transepidermal water loss (TEWL) and water content of the epidermis (WCE) on both volar forearms of the two groups, were performed during three visits at D0, D30 and after sixty days (D60) of oils treatment.

Results

The consumption of argan oil has led to a significant decrease in TEWL (p = 0.023) and a significant increase in WCE (p = 0.001). The application of argan oil has led to a significant decrease in TEWL (p = 0.01) and a significant increase in WCE (p < 0.001).

Conclusions

Our findings suggest that the daily consumption and application of argan oil have improved the skin hydration by restoring the barrier function and maintaining the water-holding capacity.

Sweat, the driving force behind normal skin: an emerging perspective on functional biology and regulatory mechanisms

The various symptoms associated with excessive or insufficient perspiration can significantly reduce a patient's quality of life. If a versatile and minimally invasive method could be established for returning sweat activity to normalcy, there is no question that it could be used in the treatment of many diseases that are believed to involve perspiration. For this reason, based on an understanding of the sweat-gland control function and sweat activity, it was necessary to conduct a comprehensive search for the factors that control sweating, such as the central and peripheral nerves that control sweat-gland function, the microenvironment surrounding the sweat glands, and lifestyle. We focused on the mechanism by which atopic dermatitis leads to hypohidrosis and confirmed that histamine inhibits acetylcholinergic sweating. Acetylcholine promotes the phosphorylation of glycogen synthesis kinase 3β (GSK3β) in the sweat-gland secretory cells and leads to sensible perspiration. By suppressing the phosphorylation of GSK3β, histamine inhibits the movement of sweat from the sweat-gland secretory cells through the sweat ducts, which could presumably be demonstrated by dynamic observations of the sweat glands using two-photon microscopy. It is expected that the discovery of new factors that control sweat-gland function can contribute to the treatment of diseases associated with dyshidrosis.