Dry condition affects desquamation of stratum corneum in vivo

Effect of indoor house dust mite concentration on canine atopic dermatitis

Introduction

House dust mites (HDM) are regarded as essential environmental allergens not only in human, but also in canine atopic dermatitis (CAD), however, there are only a few studies on the influence of indoor HDM concentration on the disease.

Methods

Our study analyzed the correlation between the indoor HDM concentration, the severity of CAD, and the residential environments in client-owned 35 AD and 13 healthy dogs. We measured the extent of CAD and severity index-04 (CADESI-04), pruritus visual analog scale (PVAS), and transepidermal water loss (TEWL), indoor relative humidity (RH) and analyzed the residential environment questionnaires to evaluate AD severity.

Results

The Der f 1 concentration had an inverse association with TEWL, and no association with CADESI-04 and PVAS. The Der f 1 concentration was significantly high in the group living near the green area and 40% or higher RH.

Discussion

Our results suggest two possibilities: (1) Living around green areas and maintaining an appropriate indoor climate may help to improve CAD clinical symptoms. (2) The HDM may contain endotoxin and when present in high concentrations in CAD, they play a preventive role by enhancing the skin barrier function. Further studies with a larger number of dogs may help further elucidate an association between CAD and Der f 1.

Analysis of clinical presentations, lip transepidermal water loss and associated dermatological conditions in patients with chronic cheilitis

Chronic cheilitis (CC) is a spectrum of inflammatory changes of unknown etiology that affect the vermilion of the lips. This study aimed to describe the epidemiology, clinical presentations and risk factors of CC. Patients with CC were recruited from the National Clinical Research Center for Oral Disease of China. A convenience sample of inhabitants who live in the same geographical region were recruited as the control group. The lip skin transepidermal water loss (TEWL) and capacitance of CC patients were compared with that of age- and gender-matched controls. Our results demonstrated that of the 109 patients with CC, 72 (66.1%; 95% CI: 57.0-75.1%) were female. The common clinical presentations of CC consisted of desquamation (n = 99; 90.8%), and/or chapping (n = 81; 74.3%), and/or pruritus (n = 64; 58.7%). Multivariable analysis showed that allergic dermatologic diseases (P < 0.001; OR: 4.5; 95% CI: 2.4-8.4), anemia (P = 0.001; OR: 3.3; 95% CI: 1.5-7.5), and indoor/outdoor alternate working environment (P < 0.001; OR: 2.1; 95% CI: 1.5-2.8) were the significant risk factors for CC. The mean lip skin TEWL was found to be significantly higher, while the capacitance was lower in CC patients compared to that of control individuals. This study provides insights into the etiopathogenesis of CC and may help clinicians to identify the most effective management strategies.

Low humidity altered the gene expression profile of keratinocytes in a three-dimensional skin model

BACKGROUND

The skin is constantly exposed to various external stimuli including humidity variations. Low humidity affects skin properties such as decreased water content of the stratum corneum, reduced skin elasticity, and itching. However, the effects of humidity on the skin cells are not completely understood. This study aimed to investigate how low humidity affects keratinocytes of the skin.

METHODS AND RESULTS

In the present study, the effects of dry environment on the gene expression profile of epidermal keratinocytes were demonstrated using a three-dimensional skin model (3D-skin), composed of keratinocytes. Exposure of 3D-skin to low humidity (relative humidity ~ 10%) increased the expression levels of various genes, including those related to signal transduction and immune system. Accordingly, p38 mitogen-activated protein kinase (MAPK) signaling in keratinocytes of the 3D-skin was activated in response to low humidity for 30 min. Additionally, several chemokines, such as chemokine (C-X-C motif) ligand 1 (CXCL1) and Chemokine (C-C motif) ligand 20 (CCL20), were up regulated after 3 h of exposure to low humidity.

CONCLUSIONS

We hypothesize that increased chemokine production may affect the immune system of the whole skin through chemoattractants. Our findings imply that keratinocytes sense low humidity and resultant activation of some cell-signaling pathways leads to variations in gene expression profiles including various chemokines. We provide evidence that keratinocytes adapt to external humidity variations.

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.

Influence of the environmental relative humidity on the inflammatory response of skin model after exposure to various environmental pollutants

The skin is an essential barrier, protecting the body against the environment and its numerous pollutants. Several environmental pollutants are known to affect the skin, inducing premature aging through mechanisms including oxidative stress, inflammation, and impairment of skin functions. Even climate conditions can impact the skin. Therefore, using a Reconstructed Human Epidermis (RHE), we tested the effect of two samples of fine particulate matters (PM_0.3-2.5 - one metals-rich sample and the other organic compounds-rich), two Volatile Organic Compounds mixtures (VOCs - from a solvent-based paint and a water-based paint) and Tobacco Smoke (TS). All pollutants affected cellular functionality, but to a lesser extent for the water-based paint VOC. This effect was enhanced when RHE were preconditioned for 2 h by a semi-dry airflow (45% relative humidity) before pollutants application, compared to preconditioning by a humid airflow (90% relative humidity). In the absence of preconditioning, IL-1α, IL-6, IL-8, and RANTES were almost systematically induced by pollutants. When RHE were preconditioned by a semi-dry or humid airflow before being subjected to pollutants, the increase of IL-1α, IL-8, and RANTES falls into two groups. Similarly to RHE not treated with pollutants, RHE treated with VOCs after preconditioning by a semi-dry airflow showed increased IL-1α, IL-8, and RANTES release. On the contrary, RHE treated with PM or TS after preconditioning by a semi-dry airflow show a lower increase in IL-1α, IL-8, and RANTES compared to preconditioning by a humid airflow. The effect of real environmental relative humidity conditions of the air, combined with acute exposure to various environmental pollutants, seemed to relate mainly to structural changes of the skin, determining the outcome of the inflammatory response depending on the physicochemical characteristics of pollutants.

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.

Impact of Climatic Variations on Drug-induced Skin Reactions in Two Different Regions of India

BACKGROUND

Around 2-3% of hospitalizations have been reported due to dermatological adverse drug reactions. Recent studies suggest that climatic variations affect the skin barrier function and extreme conditions aggravate skin disorders.

OBJECTIVE

The present study was designed to compare the impact of climatic variations on drug-induced skin reactions in the Northern and Eastern regions of India.

METHODS

We performed a one-year retrospective study to evaluate the impact of climatic variations (temperature and humidity) on drug-induced skin reactions in the Eastern (Kalyani, West Bengal) and Northern (Karnal, Haryana) regions. Drug-induced skin reactions were reported month-- wise in both the Eastern and Northern regions. Temperature and humidity levels were also noted month-wise in both regions. The direct correlation between climatic variations and the number of drug reactions were assessed using Pearson's correlation and quadratic regression analysis.

RESULTS AND DISCUSSION

Overall, 99 and 81 dermatological adverse drug reactions were reported in tertiary care hospitals in the Northern and Eastern regions, respectively. During the summer season, the humidity level was found to be low in the Northern region as compared to the Eastern region. During this period, drug-induced skin reactions were reported significantly (p<0.05) more in the Northern region as compared to the Eastern region. Furthermore, quadratic regression analysis revealed that climatic variations contributed to drug reaction variability in the Northern region (68.5%) and Eastern region (23.5%).

CONCLUSION

Therefore, the difference in the prevalence of drug-induced skin reactions may be related to the different climatic conditions among these two regions. Further studies in controlled climatic conditions should be performed for definitive correlations and to look into possible solutions.

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.

The influence of autogenic training on the physical properties of skin and cardiac autonomic activity in postmenopausal women: an exploratory study

BACKGROUND

Autogenic training (AT) is a major relaxation training technique whose clinical efficacy has been verified in dermatology. Many reports demonstrate ameliorated skin conditions in AT-treated subjects with reduced psychological stress. However, no studies have examined the effects of AT on the skin of postmenopausal women.

OBJECTIVES

We examine the influences of AT on the physical properties of skin and cardiac autonomic activity in postmenopausal women.

METHODS

Postmenopausal women were classed into an AT group and a control one. The women in the AT group were mentored by a professional to practice AT twice a day for 7 weeks. The women in the control group were instructed to close their eyes for 3 minutes instead of AT. Hydration of the stratum corneum (SC), transepidermal water loss (TEWL), skin elasticity and heart-rate variability (HRV) were measured before and after the study period to examine how they changed.

RESULTS

SC hydration and skin elasticity of the cheek, increased in both groups, and the increase was significantly higher in the AT group (n = 14) than in the control group (n = 12) (P < 0.05, Cohen's d = 1.03; P < 0.05, Cohen's d = 0.99; respectively). TEWL did not change in either group. LF/HF was lower in the AT group than in the control group (P < 0.05, Cohen's d = 0.91).

CONCLUSION

AT increased SC hydration and skin elasticity with changes in the balance of autonomic nervous system activity in postmenopausal women, implying that AT may have improvement effects on aged skin by menopause.

Facial application of high-concentration carbon dioxide prevents epidermal impairment associated with environmental changes

Purpose

The transdermal application of carbon dioxide (CO₂) gas dissolved in a solution and bathing in carbonated springs have been known to improve circulatory disorders. We aimed to elucidate and profile the effects of CO₂ application on local skin function.

Patients and methods

A liquid formulation that included high-concentration CO₂ or a control formulation was applied to the face of healthy men for 8 weeks. Quantitative analysis was performed during the dry winter months.

Results

At the site where the control formulation was applied, transepidermal water loss (TEWL) increased while the moisturizing function (conductance) of facial skin decreased during the study period. However, at the CO₂-treated site, increases in TEWL and decreases in conductance were significantly suppressed. In addition, the deterioration in scaliness and wrinkles parameters were suppressed by ≥40% at the CO₂-treated site. There were no significant differences in skin surface pH or color properties between the control and test sites.

Conclusion

This study suggests that the continuous application of a high-concentration CO₂ formulation can affect skin physiology and has the potential to suppress reductions in the barrier and moisturizing functions of the stratum corneum accompanied by desquamation, which occurs during the winter.

Involvement of the nuclear structural proteins in aging-related responses of human skin to the environmental stress

Human skin is a stratified endocrine organ with primary roles in protection against detrimental biochemical and biophysical factors in the environment. Environmental stress causes gradual accumulation of the macromolecular damage and clinical manifestations consistent with chronic inflammatory conditions and premature aging of the skin. Structural proteins of cell nucleus, the nuclear lamins and lamina-associated proteins, play an important role in the regulation of a number of signal transduction pathways associated with stress. The nuclear lamina proteins have been implicated in a number of degenerative disorders with frequent clinical manifestations of the skin conditions related to premature aging. Analysis of the molecular signatures in response of the skin to a range of damaging factors not only points at the likely involvement of the nuclear lamina in transmission of the signals between the environment and cell nucleus but also defines skin's sensitivity to stress, and therefore the capacities to counteract external damage in aging.

Ambient humidity and the skin: the impact of air humidity in healthy and diseased states

Humidity, along with other climatic factors such as temperature and ultraviolet radiation, can have an important impact on the skin. Limited data suggest that external humidity influences the water content of the stratum corneum. An online literature search was conducted through Pub-Med using combinations of the following keywords: skin, skin disease, humidity, dermatoses, dermatitis, eczema, and mist. Publications included in this review were limited to (i) studies in humans or animals, (ii) publications showing relevance to the field of dermatology, (iii) studies published in English and (iv) publications discussing humidity as an independent influence on skin function. Studies examining environmental factors as composite influences on skin health are only included where the impact of humidity on the skin is also explored in isolation of other environmental factors. A formal systematic review was not feasible for this topic due to the heterogeneity of the available research. Epidemiological studies indicated an increase in eczema with low internal (indoors) humidity and an increase in eczema with external high humidity. Other studies suggest that symptoms of dry skin appear with low humidity internal air-conditioned environments. Murine studies determined that low humidity caused a number of changes in the skin, including the impairment of the desquamation process. Studies in humans demonstrated a reduction in transepidermal water loss (TEWL) (a measure of the integrity of the skin's barrier function) with low humidity, alterations in the water content in the stratum corneum, decreased skin elasticity and increased roughness. Intervention with a humidifying mist increased the water content of the stratum corneum. Conversely, there is some evidence that low humidity conditions can actually improve the barrier function of the skin. Ambient relative humidity has an impact on a range of parameters involved in skin health but the literature is inconclusive. Further studies are needed to better delineate the interactions that can occur in normal and diseased states. Therapeutic measures might be forthcoming especially for skin diseases such as eczema, which are regarded as being characterized by 'skin dryness'. Further research examining the interaction between different environmental exposures thought to impact the skin, and indeed the interplay between genetic, environmental and immunological influences, are required.

The effects of continuous application of sunscreen on photoaged skin in Japanese elderly people - the relationship with the usage

Since photoaging of skin is caused by chronic sun exposure, it is well-recognized that regular sunscreen use can help prevent photoaging of skin in fair-skinned people. Therefore, application of sunscreen is recommended for the prevention of photoaging in many countries. However, the relationship between UV exposure and photoaging has rarely been investigated in clinical studies in Japan. In addition, there have been almost no long-term interventional studies in Japanese people. We have previously conducted a study where Japanese actinic keratosis patients were instructed to continuously apply sunscreen. The results indicated that long-term application of sunscreen is effective in suppressing actinic keratosis progression and generation. In the present study, we investigated the effects of sunscreen on photoaged skin in 14 elderly Japanese people. Skin conditions such as water content, transepidermal water loss, the number of spots, wrinkles, and skin color tone uniformity were measured and compared before and after the study. A statistically significant difference was observed only in skin surface hydration. There were large inter-individual differences in amount of sunscreen used throughout the study. The changes in the number of spots and skin color tone uniformity during the 18 months showed good correlation with amount of sunscreen being used. These results suggest an increase in the number of spots and deterioration in skin color tone uniformity in the 18-month non-sunscreen application period, and that such skin conditions improved with increasing use of sunscreen. In this study, we suggested an inhibitory effect on photoaging symptoms such as spots and skin color tone non-uniformity, by application of the appropriate amount of sunscreen over a long period of time in Japanese people, similar to Caucasians.

Desmosomes: regulators of cellular signaling and adhesion in epidermal health and disease

Desmosomes are intercellular junctions that mediate cell-cell adhesion and anchor the intermediate filament network to the plasma membrane, providing mechanical resilience to tissues such as the epidermis and heart. In addition to their critical roles in adhesion, desmosomal proteins are emerging as mediators of cell signaling important for proper cell and tissue functions. In this review we highlight what is known about desmosomal proteins regulating adhesion and signaling in healthy skin-in morphogenesis, differentiation and homeostasis, wound healing, and protection against environmental damage. We also discuss how human diseases that target desmosome molecules directly or interfere indirectly with these mechanical and signaling functions to contribute to pathogenesis.

Documentation of normal stratum corneum scaling in an average population: features of differences among age, ethnicity and body site

BACKGROUND

Scaling skin involves an imbalance between cell proliferation and desquamation, resulting in partially detached corneocytes at the stratum corneum (SC) surface that become visible as they scatter light.

OBJECTIVES

The purpose of this study was to document scaling skin with no associated pathology, to estimate the range of normal corneocyte detachment in the average population, and to determine if age, pigmentation and/or body sites of different exposures contribute to differences observed in the SC.

METHODS

Healthy African-American and Caucasian female subjects (n = 151) from a typical central New Jersey population, aged between 14 and 75 years, were evaluated on the dorsal forearm and upper inner arm. Dermatoscopy and adhesive tape were used to evaluate the appearance and adhesion of surface corneocytes. Transepidermal water loss and conductivity were measured to assess water-handling properties of the SC. Measurements were conducted during the winter.

RESULTS

Corneocyte detachment observed with dermatoscopy became more prevalent with age and was more severe on the dorsal forearm and in Caucasian subjects. The distribution of the amount of corneocyte removal with adhesive tape increased with age. The range of values was larger in the dorsal forearm than the upper inner arm and was greater in Caucasian subjects than African-American subjects. Minimal changes were observed for water-handling properties.

CONCLUSIONS

The architecture of the outer SC appears different between ages, body sites of different exposures, and individuals of different pigmentation groups, but minimal differences in water-handling properties are observed.

Infant skin physiology and development during the first years of life: a review of recent findings based on in vivo studies

Infant skin is often presented as the cosmetic ideal for adults. However, compared to adult skin it seems to be more prone to develop certain pathological conditions, such as atopic dermatitis and irritant contact dermatitis. Therefore, understanding the physiology of healthy infant skin as a point of reference is of interest both from the cosmetic as well as from the clinical point of view. Clinical research on healthy infants is, however, limited because of ethical considerations of using invasive methods and therefore until recently data has been scarce. Technical innovations and the availability of non-invasive in vivo techniques, such as evaporimetry, electrical impedance measurement, in vivo video and confocal microscopy, and in vivo fibre-optic based spectroscopy, opened up the field of in vivo infant skin physiology research. Studies incorporating such methods have demonstrated that compared to adult, infant skin continues to develop during the first years of life. Specifically, infant skin appears to have thinner epidermis and stratum corneum (SC) as well as smaller corneocytes at least until the second year of life. The water-handling properties are not fully developed before the end of the first year and infant SC contains more water and less amounts of natural moisturizing factors. Such findings re-evaluate the old notions that skin is fully matured at birth. Armed with this knowledge, we are in a position not only to better understand infant dermatological conditions but also to design better skin care products respecting the distinct qualities of infant skin.

The multifunctional role of ectoine as a natural cell protectant

The protective properties of ectoine, formerly described for only extremophilic microorganisms, can be transferred to human skin. Our present data show that the compatible solute ectoine protects the cellular membrane from damage caused by surfactants. Transepidermal water loss measurements in vivo suggest that the barrier function of the skin is strengthened after the topical application of an oil in water emulsion containing ectoine. Ectoine functions as a superior moisturizer with long-term efficacy. These findings indicating that ectoine is a strong water structure-forming solute are explained in silico by means of molecular dynamic simulations. Spherical clusters containing (1) water, (2) water with ectoine, and (3) water with glycerol are created as model systems. The stronger the water-binding activity of the solute, the greater the quantity of water molecules remaining in the cluster at high temperatures. Water clusters around ectoine molecules remain stable for a long period of time, whereas mixtures of water and glycerol break down and water molecules diffuse out of the spheres. On the basis of these findings, we suggest that the hydrogen bond properties of solutes are not solely responsible for maintaining the water structure form. Moreover, the particular electrostatic potential of ectoine as an amphoteric molecule with zwitterionic character is the major cause for its strong affinity to water. Because of its outstanding water-binding activity, ectoine might be especially useful in preventing water loss in dry atopic skin and in recovering skin viability and preventing skin aging.

Alterations in health examination items and skin symptoms from exposure to ultra-low humidity

OBJECTIVES

Several lines of evidence have shown that insufficient humidity could result in health problems but no studies have been performed in ultra-low humidity (ULH) environments. The aims of this study are to investigate the health examination items alterations and skin symptoms of workers exposed to ULH environment based on a longitudinal study design.

METHODS

Twelve male ULH (RH = 1.5%) workers and 12 age-sex-matched reference workers were selected. The examination items in blood and urine as well as the skin problems were compared between ULH workers and controls, and between ULH workers in 2000 and 2003. Biochemistry analysis of blood and urine were implemented from annual health examinations. Information on skin symptoms and diseases were obtained from a structured questionnaire in 2000 and 2003.

RESULTS

The alterations in mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and total cholesterol in blood analysis and only sediment-WBC in urine analysis were found significantly different in 2000. These changes were almost fully recovered in 2003 although a consistently significant elevation in the urine specific gravity was found during the 3-year follow-up period. Skin disorders, however, showed an earlier elevated itching symptom in lower limb and pretibial that developed to physician-diagnosed contact dermatitis.

CONCLUSIONS

Long-term ULH exposure could cause progressive pathological changes in the skin and urine concentration elevation. Because low humidity condition occurs frequently in air-conditioned buildings, the findings of this study suggest the population long-term exposed to low humidity should be cautious about health manifestations living in a low humidity environment. While the indoor environment is equipped with an air-conditioner, continuous monitoring on the humidity is recommended.

The use of near-infrared spectroscopy in skin care applications

BACKGROUND

Near-infrared (NIR) spectroscopy was used to document the skin water content as a function of product usage and changes in the % relative humidity (%RH) in vitro and in vivo. The objective of the investigation was to determine if the NIR could provide comparable skin water content information as that obtained using gravimetric, conductivity, or visual assessment methods without having to invoke complex chemometric calculations.

METHODS

NIR data were obtained using an NIR5000 spectrophotometer with a fiber optic probe (Smartprobe) attachment to complete the clinical studies and a Direct Contact Analyzer module to carry out the in vitro experiments. Conductivity measurements were completed using the Skicon 200, which measures conductance at a fixed frequency of 3.5 MHz. Three moisturization-based clinical studies were carried out assessing the NIR's ability to detect skin hydration changes. In Clinical Study A, NIR and Skicon data were collected for panelists who had only washed their outer calf with water over a 4-week period. During this time, the daily average %RH was recorded. In Clinical Study B, 10% solutions of glycerin, choline chloride, and the sodium salt of pyrrolidone carboxylic acid were applied to the panelist's outer calf and biophysical measurements were completed to assess the hydration and desorption properties of these humectants. In Clinical Study C, a 10% solution of choline chloride was applied to panelist's outer calf and the cumulative effect of using this product was evaluated over a 3-week period. For all in vitro studies, porcine skin was used as the substrate.

RESULTS

Comparable NIR, Skicon, and visual dryness results were obtained for most of the product usage-based clinical experiments completed. However, the NIR was particularly more effective at detecting skin water content differences as a function of %RH changes. In the absence of abrupt (>50%) relative humidity variations, there was a direct correlation between the NIR readings and the %RH (R(2)=0.83) unlike what was observed for the Skicon measurements (R(2)=0.22).

CONCLUSIONS

NIR spectroscopy demonstrated the changes in the skin water content as a function of product usage; the results were consistent with those obtained using the Skicon conductivity meter and visual dryness assessment scores. More importantly, the differences detected were obtained without having to use chemometric manipulations in the data analysis as is the common practice. Of all the methods used, the NIR gave the best linear regression for %RH-induced skin water content changes.

Functional properties of the stratum corneum in patients with diabetes mellitus: similarities to senile xerosis

BACKGROUND

Although diabetes mellitus is known to induce many pathophysiological changes in the skin, none of the earlier studies has focused on the state of the stratum corneum (SC) in patients with diabetes. In our previous report on a diabetic mouse model, we described a decreased SC hydration state and abnormalities in the function of the sebaceous gland together with a normally retained barrier function of the SC.

OBJECTIVES

To examine the functional changes of the SC in patients with diabetes.

METHODS

The following values were measured in 49 patients with diabetes: fasting plasma glucose (FPG) and haemoglobin A1c (HbA1c); skin surface lipid level on the forehead; and high-frequency conductance (HFC) and transepidermal water loss (TEWL) of the SC of the volar forearm and extensor surface of the lower leg. These functions of the SC were compared in two pairs of patient groups, i.e. between groups with high and low FPG, and between groups with high and low HbA1c.

RESULTS

The HFC levels on the extensor leg and volar forearm were significantly lower in the group with high FPG (FPG > 110 mg dL(-1)) than in the group with low FPG (FPG < 110 mg dL(-1)), although TEWL values were almost the same in these two groups. The skin surface lipids on the forehead were significantly lower in the former than in the latter. The HFC did not differ significantly between the group with high HbA1c (HbA1c > 5.8%) and the group with low HbA1c (HbA1c < 5.8%), whereas the TEWL of the volar forearm was slightly lower in the former than in the latter.

CONCLUSIONS

These new results as well as our earlier results with diabetic mice suggest that patients with diabetes mellitus tend to show a reduced hydration state of the SC together with decreased sebaceous gland activity, without any impairment of the SC barrier function.

Air flow at different temperatures increases sodium lauryl sulphate-induced barrier disruption and irritation in vivo

BACKGROUND

Combined exposure to dry climatic conditions and local heat sources together with detergents represents a common workplace situation. These conditions may support the induction of chronic barrier disruption leading subsequently to irritant contact dermatitis (ICD).

OBJECTIVES

To test the irritant and barrier disrupting properties of air flow at different temperatures and velocities.

METHODS

Using noninvasive biophysical measurements such as transepidermal water loss (TEWL) (TM 210; Courage & Khazaka, Cologne, Germany) we assessed the effects of short-term exposure to air flow at different temperatures (24 degrees C and 43 degrees C) in combination with sodium lauryl sulphate (SLS) 0.5% on the skin of 20 healthy volunteers in a tandem repeated irritation test. Chromametry was used to control the accuracy of the SLS irritation model.

RESULTS

In our study air flow alone did not lead to a significant increase in TEWL values. Sequential treatment with air flow and SLS led to an impairment of barrier function and irritation stronger than that produced by SLS alone. The two different air flow temperatures led to different skin temperatures but had no influence on permeability barrier function.

CONCLUSIONS

Warm air flow has an additional effect on the SLS-induced barrier disruption in a tandem irritation test with sequential exposure to SLS/air flow. This combination is suspected to promote ICD in workplace and household situations, especially in short-term applications as tested in our model.

Unsaturated Fatty Acids Induce Calcium Influx into Keratinocytes and Cause Abnormal Differentiation of Epidermis

Abnormal follicular keratinization is involved in comedogenesis in acne vulgaris. We recently demonstrated that calcium influx into epidermal keratinocytes is associated with impaired skin barrier function and epidermal proliferation. Based on these results, we hypothesized that sebum components affect calcium dynamics in the keratinocyte and consequently induce abnormal keratinization. To test this idea, we first observed the effects of topical application of sebum components, triglycerides (triolein), saturated fatty acids (palmitic acid and stearic acid), and unsaturated fatty acids (oleic acid and palmitoleic acid) on hairless mouse skin. Neither triglyceride nor saturated fatty acids affected the skin surface morphology or epidermal proliferation. On the other hand, application of unsaturated fatty acids, oleic acid, and palmitoleic acid induced scaly skin, abnormal keratinization, and epidermal hyperplasia. Application of triglycerides and saturated fatty acids on cultured human keratinocytes did not affect the intracellular calcium concentration ([Ca(2+)](i)), whereas unsaturated fatty acids increased the [Ca(2+)](i) of the keratinocytes. Moreover, application of oleic acid on hairless mouse skin induced an abnormal calcium distribution in the epidermis. These results suggest that unsaturated fatty acids in sebum alter the calcium dynamics in epidermal keratinocytes and induce abnormal follicular keratinization.

Transepidermal water loss and skin capacitance alterations among workers in an ultra-low humidity environment

No studies have been performed evaluating skin barrier alterations in humans exposed to ultra-low humidity (ULH) in spite of several lines of evidence from animal experiments suggesting that the skin barrier is altered on exposure to ULH. The objectives of this study were to assess barrier function changes in workers occupationally exposed to ULH (relative humidity 1.5%), and to evaluate whether the exposure duration shows a dose-response relationship with transepidermal water loss (TEWL) and skin capacitance. A total of 49 male workers exposed to ULH for 12 h per working day were classified into five subgroups based on their ULH exposure duration (<0.5 months, 0.5-1.0 month, 1.1-10.0 months, 10.1-20.0 months, and >20.0 months). A group of 12 age-matched male laboratory workers from a normal humidity environment were recruited as a control group. TEWL and skin capacitance were measured to evaluate their skin barrier function. TEWL measurements showed a significant decline (8.3+/-0.4 vs 10.0+/-0.4 g m(-2) h(-1), P < 0.05) but no differences were found in skin capacitance (39.7+/-1.3 a.u. vs 45.0+/-2.4 a.u., P = 0.68) between the whole ULH exposure group and the control group. Maximum decreases in TEWL and skin capacitance were seen in the subgroups exposed for <0.5 months and 0.5-1.0 month, respectively. Almost completely natural recovery occurred in skin capacitance after 20 months ULH exposure, in contrast to less than 90% recovery in TEWL. Three stages were defined according to the pattern of alterations in TEWL and skin capacitance in relation to ULH exposure duration. A positive association between TEWL and skin capacitance occurred in the control group and stage I but a negative correlation in stage II. No correlation was found in stage III. Our study demonstrated that workers exposed to a ULH environment could exhibit skin barrier alterations. Both TEWL and skin capacitance decreased within 2 weeks of ULH exposure. The maximum alterations in TEWL and skin capacitance occurred during 0.5-1.0 months and 2 weeks, respectively. TEWL recovered partially and more slowly than skin capacitance which recovered earlier and almost completely.

Dry environment increases mast cell number and histamine content in dermis in hairless mice

BACKGROUND

A variety of skin diseases, such as atopic dermatitis, senile xerosis or psoriasis tends to worsen during the dry winter season. These skin diseases are also characterized by itch sensation.

OBJECTIVES

To evaluate the generation of histamine in the dermis of hairless mice kept under various conditions of environmental humidity.

MATERIALS AND METHODS

We carried out the quantification of mast cell population and evaluated the histamine content in the epidermis, dermis and serum of the mice kept under various conditions of environmental humidity.

RESULTS

Histamine content in the dermis of the mice kept in a low environmental humidity (relative humidity < 10%) for 3 and 5 days was significantly higher than that of the mice kept in a high environmental humidity (relative humidity > 80%) for the same period of time. No significant difference was observed on the histamine content in the epidermis between the two humidity groups. The number of mast cells in the dermis of the mice kept in the low environmental humidity was significantly higher than that of the mice kept in the high environmental humidity. Topical application of petrolatum reduced the level of histamine in the dermis of the mice under the low environmental humidity.

CONCLUSIONS

These results suggest that a low environmental humidity increases mast cell number and dermal histamine content.

Changes in environmental humidity affect the water-holding property of the stratum corneum and its free amino acid content, and the expression of filaggrin in the epidermis of hairless mice

BACKGROUND

Seasonal changes affect the condition of skin and may trigger various cutaneous disorders.

OBJECTIVE

To clarify the effects of the environmental humidity on the skin pathology, we studied the effects of the humidity on a water-holding function of the stratum corneum.

METHODS

We evaluated the skin surface conductance, amino acid in the stratum corneum, and immunoreactivity of filaggrin of the epidermis of hairless mice kept in different environmental humidity.

RESULTS

Skin surface conductance in the stratum corneum of hairless mice 3-7 days after transfer from a humid environment (>80% relative humidity) to a dry (<10% relative humidity) environment, was significantly lower than that of the mice transferred from a normal environment (relative humidity=40-70%) to a dry environment. The free amino acid content in the stratum corneum significantly decreased 24 h after we transferred the mice from a normal to a dry condition, then it recovered to the original level within 3 days, while the mice transferred from a humid to a dry condition showed a significantly lower amino acid content even 7 days after the transfer. No obvious change was observed in the relative composition of the major components of the free amino acids during the experiments. Immunoreactivity of filaggrin, which is the main precursor of free amino acids in the stratum corneum, also became faint in the epidermis of the mice transferred from a humid or normal to a dry environment.

CONCLUSION

These results suggested that a drastic decrease in the environmental humidity reduced the total free amino acid generation and consequently induced skin surface dryness in the stratum corneum.

The skin barrier state of aged hairless mice in a dry environment

BACKGROUND

Many elderly people have chronic xerosis, and frequently experience an exacerbation during winter.

OBJECTIVES

To investigate the barrier state of aged murine skin with or without barrier disruption in a dry environment.

METHODS

Aged and young hairless mice were kept separately in dry and normal conditions for 9 days. Acetone treatment was used to perturb the skin barrier. Skin barrier function was measured as transepidermal water loss (TEWL), and morphological changes in the epidermis were studied by electron microscopy.

RESULTS

The baseline TEWL was not higher in the dry environment. The number of stratum corneum (SC) layers and the epidermal thickness of aged mice increased in the dry environment. The recovery rate of the aged skin barrier was neither accelerated nor delayed in the dry environment. In the normal environment, aged mice recovered more slowly than young mice. After barrier perturbation in the aged mice, changes in SC layers and in epidermal thickness were similar in the two environments. The secretion and number of lamellar bodies did not differ between the two environments.

CONCLUSIONS

We confirmed that a dry environment induces epidermal proliferation and scaling in both aged and young mice. However, no remarkable difference was found in the skin barrier recovery of aged hairless mice in a dry environment.

Epidermal interleukin-1 alpha generation is amplified at low humidity: implications for the pathogenesis of inflammatory dermatoses

BACKGROUND

We have previously reported that low humidity amplifies the hyperproliferative and inflammatory response to barrier disruption. Other reports suggest that epidermal interleukin (IL)-1 alpha is stimulated by various factors related to epidermal inflammation and that it may induce other proinflammatory molecules.

OBJECTIVES

To evaluate the generation of IL-1 alpha in the skin of hairless mice kept under various conditions of environmental humidity.

METHODS

We carried out an immunohistochemical study, and evaluated epidermal IL-1 alpha mRNA and protein levels, and release of IL-1 alpha from skin after tape stripping, in hairless mice kept under low or high humidity.

RESULTS

The immunohistochemical study showed that the amount of IL-1 alpha in the epidermis was higher in animals kept in a low-humidity environment than in a high-humidity one. The epidermal IL-1 alpha mRNA and protein levels increased significantly when the animals were kept under low humidity. Moreover, the release of IL-1 alpha from skin immediately after tape stripping was significantly higher in animals kept in a low-humidity environment than in a high-humidity one.

CONCLUSIONS

These results suggest that IL-1 alpha is an important factor in mediating the relationship between environmental humidity and epidermal pathology.

Influence of dry environment on epidermal function

Recent studies have demonstrated that a dry environment contributes to the exacerbation of cutaneous disorders such as epidermal hyperplasia, mast cell degranulation, and cytokine secretion. The effects of a dry environment on the skin can be prevented by occlusion with water-impermeable material or topical application of a humectant. The stratum corneum, which protects internal organs from the environment, has two functions: a water-impermeable barrier function and a buffer function against a dry environment. Regulation of protease activity or ionic balance in the epidermis can accelerate barrier repair after injury. Improvement of the stratum corneum homeostasis can ameliorate skin damage induced by barrier disruption in a dry environment.