Transepidermal Water Loss Measurements Research Articles

Comparison of Intact Fish Skin Graft and Allograft as Temporary Coverage for Full-Thickness Burns: A Non-Inferiority Study.

The extent and depth of burn injury may mandate temporary use of cadaver skin (allograft) to protect the wound and allow the formation of granulation tissue while split-thickness skin grafts (STSGs) are serially harvested from the same donor areas. However, allografts are not always available and have a high cost, hence the interest in identifying more economical, readily available products that serve the same function. This study evaluated intact fish skin graft (IFSG) as a temporary cover to prepare the wound bed for STSG application. Thirty-six full-thickness (FT) 5 × 5 cm burn wounds were created on the dorsum of six anesthetized Yorkshire pigs on day -1. To mimic the two-stage clinical situation, on day 0, wounds were excised down to a bleeding wound bed and a temporary cover (either IFSG or cadaver porcine skin) was applied; then, on day 7, wounds were debrided to a viable wound bed prior to the application of autologous 1.5:1 meshed STSG (mSTSG). Rechecks were performed on days 14, 21, 28, 45, and 60 with digital images, non-invasive measurements, and punch biopsies. The IFSG created a granulated wound bed receptive to the application of an mSTSG. FT burn wounds treated with an IFSG had similar outcome measures, including contraction rates, trans-epidermal water loss (TEWL) measurements, hydration, and blood perfusion levels, compared to cadaver skin-treated burn wounds. Pathology scoring indicated significant differences between the allograft- and IFSG-treated wounds on day 7, with the IFSG having increased angiogenesis, granulation tissue formation, and immune cells. Pathology scoring indicated no significant differences once mSTSGs were applied to wounds. The IFSG performed as well as cadaver skin as a temporary cover and was not inferior to the standard of care, suggesting the potential to transition IFSGs into clinical use for burns.

Frequent oil-baths and skin barrier during infancy in the PreventADALL study.

In the general population randomized controlled PreventADALL trial, frequent emollient bath additives from 2 weeks of age did not prevent atopic dermatitis, while the effect on skin barrier function throughout infancy is not established. The primary aim of this exploratory substudy was to assess the effect of mineral based oil-baths on transepidermal water loss (TEWL) and dry skin through infancy, and secondarily to explore if filaggrin (FLG) mutations modified the effect. Overall 2153 infants randomized to Skin intervention (SI)(n=995) (oil-bath 4 times/week from 2 weeks through 8 months) or No skin intervention (NSI)(n=1158) with TEWL measurements at 3, 6 and/or 12 months of age were included, of whom 1683 infants also had available FLG mutation status. Effects of the skin intervention on TEWL and dry skin through infancy were assessed by mixed effects regression modelling. Background characteristics and protocol adherence were collected from electronic questionnaires, birth records and weekly diaries. The TEWL (95% CI) was in average 0.42 g/m2/h (0.13-0.70, p= 0.004) higher in the SI compared to NSI group through the first year of life, with significantly higher levels at 3 months, (8.6 (8.3-9.0) versus 7.6 (7.3-7.9)), but similar at 6 and 12 months. Dry skin was significantly more often observed in the NSI group compared to the SI group at 3 months (59% versus 51%) and at 6 months of age (63% versus 53%), while at 12 months of age, the difference was no longer significant. At 3 months, the TEWL of FLG mutation carriers was similar to the TEWL in SI group. No interaction between skin intervention and FLG mutation was found in the first year of life. Infants with frequent oil-baths from 2 weeks of age had reduced skin barrier function through infancy compared to controls, largely attributed to higher TEWL at 3 months of age, while the skin at 3 and 6 months appeared less dry in infants subjected to the skin intervention.

Emulsions containing allantoin and D-panthenol as attractive moisturizing agents

Dry skin is the common problem affecting people which triggers many unpleasant symptoms such as roughness, peeling, burning, itching and greater sensitivity to injury and external conditions. One method to assess the water loss of skin is transepidermal water loss (TEWL) measurement. Various active substances, for instance allantoin and D-panthenol, can be used to overcome the symptoms of the dry skin. In this study, emulsions containing allantoin and D-panthenol as moisturizing agents and various oils (liquid paraffin, Cannabis sativa, Baobab and Coconut oil) were developed. The prepared emulsions were characterized by: visual and microscopic appearance and pH values. Stability analysis was conducted by centrifuge test and sensory test using sensory sensation was evaluated. Rheological experiments were performed using a rheometer, while mechanical and adhesion tests by texture analyzer. TEWL values were measured using a tewameter, after application of the emulsions to the responders skin. TEWL study noticed that regular permanent use of moisturizing emulsions with allantoin and D-panthenol limited the water loss. In conclusion, it can be stated that emulsions containing allantoin and D-panthenol as active agents and Coconut oil as oily ingredient are attractive formulations with moisturizing effect and good application features.

Skin Barrier Function Assessment: Electrical Impedance Spectroscopy Is Less Influenced by Daily Routine Activities Than Transepidermal Water Loss.

Skin barrier function assessment is commonly done by measuring transepidermal water loss (TEWL). An important limitation of this method is the influence of intrinsic and extrinsic factors. Electrical impedance spectroscopy (EIS) is a lesser-established method for skin barrier function assessment. Some influential factors have been described, but no guidelines exist regarding the standardization of these measurements. To evaluate the effect size of daily routine activities on TEWL and EIS, as well as their correlation with age and anatomical differences. Healthy participants (n=31) were stratified into three age groups (18-29, 30-49, and ≥50 years). In a climate-controlled room, EIS and TEWL measurements were performed on the left and right volar forearm and abdomen. Body cream application decreased TEWL and EIS values after 15 and 90 minutes. Skin washing decreased TEWL for 15 minutes and EIS values for at least 90 minutes. TEWL was increased 5 minutes after moderate to intense exercise. Coffee intake increased TEWL on the abdomen after 60 minutes. TEWL and EIS values did not correlate with participants' age and no anatomical differences were observed. No correlation was observed between TEWL and EIS. Body cream application and skin washing should be avoided at least 90 minutes prior to measurements of TEWL and EIS. Exercise and coffee intake should also be avoided prior to TEWL measurements. EIS may be a promising tool for skin barrier function assessment as it is less affected by daily routine activities than TEWL.

Comparison of skin barrier abnormalities and epidermal ceramide profiles among three ω-O-acylceramide synthesis-deficient mouse strains

BackgroundThe epidermis contains many structurally diverse ceramides, which form the skin permeability barrier (skin barrier). Mutations in genes involved in the synthesis of ω-O-acylceramides (acylceramides) and protein-bound ceramides cause ichthyosis. ObjectiveWe aimed to elucidate the relationship between the degree of skin barrier impairment and changes in epidermal ceramide profiles caused by mutations in acylceramide synthesis genes. MethodsKnockout (KO) mice of three genes—fatty acid (FA) ω-hydroxylase Cyp4f39 (human CYP4F22 ortholog), FA elongase Elovl1, and acyl-CoA synthetase Fatp4—were subjected to transepidermal water loss measurement, toluidine blue staining, and epidermal ceramide profiling via liquid chromatography coupled with tandem mass spectrometry. ResultsTransepidermal water loss was highest in Cyp4f39 KO mice, followed by Elovl1 KO and Fatp4 KO mice, and Cyp4f39 KO mice also showed the strongest degree of toluidine blue staining. In Cyp4f39 KO, Elovl1 KO, and Fatp4 KO mice, acylceramide levels were 0.6%, 1.6%, and 12%, respectively, of those in wild-type mice. Protein-bound ceramide levels were 0.2%, 30%, and 33%, respectively, of those in wild-type mice. We also observed a near-complete absence of ω-hydroxy ceramides in Cyp4f39 KO mice, reduced total ceramide levels and shortened FA moieties in Elovl1 KO mice, and increased hydroxylated ceramide levels and slightly shortened FA moieties in Fatp4 KO mice. ConclusionsThe degree of reduction in protein-bound ceramide levels is probably related to the severity of skin barrier defects in these three strains. However, reduced acylceramide levels and other changes in ceramide composition unique to each KO strain are also involved.

432 Fluctuations in Equine Cutaneous Ph and Trans-Epidermal Water Loss Associated with Anatomical Location, Time, and Weather

Abstract Although skin health is of critical importance for all horse owners, understanding of cutaneous pH and trans-epidermal water loss (TEWL) and the normal ranges of these variables is lacking. Cutaneous pH and TEWL measures provide insight into the barrier function of the epidermis and have the potential to determine the resident dermal microbiota. However, these measures have been recorded to fluctuate due to a variety of factors such as environment and anatomical locations in other species. Accordingly, the objectives of this study were to identify the impacts of anatomical location, weather, and time of day on cutaneous pH and TEWL in equines. This study utilized nine (n = 9) stock type mares, group-housed in a pasture setting at Southern Illinois University Equine Center. Researchers measured cutaneous pH and TEWL three times (6:00 AM, 12:00 PM, 6:00 PM) daily across five anatomical locations (nose, whither, heart-girth, mid-back, and base of tail) for five consecutive days. All statistical analysis was conducted using SAS On Demand for Academics (P < 0.05). Analysis of changes in variables associated with time, anatomical location, and day were conducted utilizing a PROC GLM three-way repeated measures ANOVA utilizing a Greenhouse-Geiser correction. Cutaneous pH results displayed significant main effects of day (P = 0.0052) and time (P = 0.0073) as well as a significant interaction of day and location (P = 0.0004). Mean cutaneous pH fluctuated daily, however, certain anatomical locations fluctuated more than others each day. Additionally, pH was highest in the morning (mean of 7.28) and lowest in the evening (mean 7.011). However, the mean overall pH for the study is 7.14 which is congruent with other work. TEWL measurements had significant main effects of day (P < 0.0001), time (P < 0.0001), and location (P = 0.0231), as well as a significant interaction of day, time, and location (P < 0.0001). TEWL measurements fluctuated with day, likely a result of weather changes. Mean TEWL measurements were less in the morning (mean 24.68) and greatest in the afternoons (mean 38.52). Overall mean TEWL measurement was 30.25. The results of this work indicate fluctuations in dermal barrier variables are associated with day, anatomical location, and time of day. These findings may have implications for applications of dermal treatments for horses as well as catalog the natural fluctuations which may affect future research.

Effects of 1,3-propanediol associated, or not, with butylene glycol and/or glycerol on skin hydration and skin barrier function.

This study aimed to assess the effect of 1,3-propanediol at different concentrations (5%, 10%, or 15%), either applied alone or in combination with butylene glycol (BG) (5%) and/or glycerol (5%), on skin hydration and skin barrier function. The measurements were conducted using capacitance to determine skin hydration and trans epidermal water loss (TEWL) rates to evaluate skin barrier function. A total of 30 healthy female subjects participated in the study. Capacitance and TEWL measurements were conducted at multiple time points, including before application and at 15 min, 2 and 8 h after the humectants were applied to the forearms of the subjects. All the subjects provided written informed consent. The 1,3-propanediol in all concentrations and in all combinations (with BG and/or glycerol) increased skin hydration and improved skin barrier function 15 min, 2 and 8 h after application. Glycerol increased the hydration performance of 1,3-propanediol. The application of 1,3-propanediol at a concentration of 15%, either alone or in combination with other humectants, reduced the TEWL to a greater extent than lower concentrations of 1,3-propanediol. Furthermore, the addition of glycerol to 1,3-propanediol 15% improved the skin barrier and reduced TEWL when compared with 1,3-propanediol alone and with the combination of 1,3-propanediol + BG. The humectants significantly improved skin hydration and reduced TEWL throughout the 8-h time course. The increase in 1,3-propanediol concentration, as well as its combination with glycerol, provided a greater benefit to the skin, improving both hydration and the skin barrier function.

Household laundry detergents disrupt barrier integrity and induce inflammation in mouse and human skin.

Epithelial barrier impairment is associated with many skin and mucosal inflammatory disorders. Laundry detergents have been demonstrated to affect epithelial barrier function in vitro using air-liquid interface cultures of human epithelial cells. Back skin of C57BL/6 mice was treated with two household laundry detergents at several dilutions. Barrier function was assessed by electric impedance spectroscopy (EIS) and transepidermal water loss (TEWL) measurements after the 4 h of treatments with detergents. RNA sequencing (RNA-seq) and targeted multiplex proteomics analyses in skin biopsy samples were performed. The 6-h treatment effect of laundry detergent and sodium dodecyl sulfate (SDS) was investigated on ex vivo human skin. Detergent-treated skin showed a significant EIS reduction and TEWL increase compared to untreated skin, with a relatively higher sensitivity and dose-response in EIS. The RNA-seq showed the reduction of the expression of several genes essential for skin barrier integrity, such as tight junctions and adherens junction proteins. In contrast, keratinization, lipid metabolic processes, and epidermal cell differentiation were upregulated. Proteomics analysis showed that the detergents treatment generally downregulated cell adhesion-related proteins, such as epithelial cell adhesion molecule and contactin-1, and upregulated proinflammatory proteins, such as interleukin 6 and interleukin 1 beta. Both detergent and SDS led to a significant decrease in EIS values in the ex vivo human skin model. The present study demonstrated that laundry detergents and its main component, SDS impaired the epidermal barrier in vivo and ex vivo human skin. Daily detergent exposure may cause skin barrier disruption and may contribute to the development of atopic diseases.

Efficacy of a Cosmetic Treatment in Decreasing the Mild-to-Moderate Atopic Dermatitis in Babies, Children, and Adults: A Pilot Study

Atopic dermatitis (AD) is a chronic inflammatory and pruritic skin disease with a worldwide progressive increase in its incidence. In this clinical study, we studied the effect of a cosmetic treatment composed of a cleanser, and a body and face cream, on subjects (babies, children, and adults) suffering from mild-to-moderate AD. The product effect on AD clinical signs was investigated by SCORing Atopic Dermatitis (SCORAD) index, subjective evaluation, skin erythema index, and transepidermal water loss (TEWL) measurements. The products were shown to be effective in improving the AD scoring by SCORAD in all the groups, and a trend towards the decrease of the erythema index and the TEWL in the adult population. An improvement in itching sensation, skin redness, and skin dryness scoring was also reported by the subjects. Results from this study demonstrate the efficacy of the tested products in decreasing the overall AD severity through 28 days of treatment. Overall, the first results occurred within 14 days of treatment.

Transepidermal water loss rises before food anaphylaxis and predicts food challenge outcomes.

Food allergy (FA) is a growing health problem requiring physiologic confirmation via the oral food challenge (OFC). Many OFCs result in clinical anaphylaxis, causing discomfort and risk while limiting OFC utility. Transepidermal water loss (TEWL) measurement provides a potential solution to detect food anaphylaxis in real time prior to clinical symptoms. We evaluated whether TEWL changes during an OFC could predict anaphylaxis onset. Physicians and nurses blind to TEWL results conducted and adjudicated the results of all 209 OFCs in this study. A study coordinator measured TEWL throughout the OFC and had no input on OFC conduct. TEWL was measured two ways in two separate groups. First, TEWL was measured using static, discrete measurements. Second, TEWL was measured using continuous monitoring. Participants who consented gave blood before and after OFCs for biomarker analyses. TEWL rose significantly (2.93 g/m2/h) during reactions and did not rise during non-reacting OFCs (-1.00 g/m2/h). Systemic increases in tryptase and interleukin-3 were also detected during reactions, providing supporting biochemical evidence of anaphylaxis. The TEWL rise occurred 48 minutes earlier than clinically evident anaphylaxis. Continuous monitoring detected a significant rise in TEWL that presaged positive OFCs, but no rise was seen in OFCs with no reaction, providing high predictive specificity (96%) for anaphylaxis against non-reactions 38 minutes prior to anaphylaxis. During OFCs, a TEWL rise anticipates a positive clinical challenge. TEWL presents a novel monitoring modality that may predict food anaphylaxis and facilitate improvements in OFC safety and tolerability.

Evaluation of skin barrier function based on skin dermoscopic features in patients with rosacea.

Evaluation of skin barrier function based on skin dermoscopic features in patients with rosacea.

Exosome from IFN-γ-Primed Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells Improved Skin Inflammation and Barrier Function.

The pathogenesis of atopic dermatitis (AD) is multifactorial, including immune dysregulation and epidermal barrier defects, and a novel therapeutic modality that can simultaneously target multiple pathways is needed. We investigated the therapeutic effects of exosomes (IFN-γ-iExo) secreted from IFN-γ-primed induced pluripotent stem cell-derived mesenchymal stem cells (iMSC) in mice with Aspergillus fumigatus-induced AD. IFN-γ-iExo was epicutaneously administered to mice with AD-like skin lesions. The effects of IFN-γ-iExo treatment were investigated through clinical scores, transepidermal water loss (TEWL) measurements, and histopathology. To elucidate the therapeutic mechanism, we used an in vitro model of human keratinocyte HaCaT cells stimulated with IL-4 and IL-13 and performed extensive bioinformatics analysis of skin mRNA from mice. The expression of indoleamine 2,3-dioxygenase was higher in IFN-γ primed iMSCs than in iMSCs. In human keratinocyte HaCaT cells, treatment with IFN-γ-iExo led to decreases in the mRNA expression of thymic stromal lymphopoietin, IL-25, and IL-33 and increases in keratin 1, keratin 10, desmoglein 1, and ceramide synthase 3. IFN-γ-iExo treatment significantly improved clinical and histological outcomes in AD mice, including clinical scores, TEWL, inflammatory cell infiltration, and epidermal thickness. Bioinformatics analysis of skin mRNA from AD mice showed that IFN-γ-iExo treatment is predominantly involved in skin barrier function and T cell immune response. Treatment with IFN-γ-iExo improved the clinical and histological outcomes of AD mice, which were likely mediated by restoring proper skin barrier function and suppressing T cell-mediated immune response.

Evaluation of skin barrier functions in patients with breast cancer-related lymphedema: Measurement of stratum corneum hydration, sebum level, and transepidermal water loss

Evaluation of skin barrier functions in patients with breast cancer-related lymphedema: Measurement of stratum corneum hydration, sebum level, and transepidermal water loss

P102 Severe atopic eczema is associated with reduced acne vulgaris in Bangladeshi children and young adults: a retrospective analysis from a cross-sectional study

Abstract Atopic eczema (AE) is the most common inflammatory dermatosis, affecting up to 20% of children. Loss of function (LoF) mutations in FLG are the most strongly implicated genetic risk factor for eczema. To understand the effect of FLG on the pathobiology of AE, we knocked down FLG in primary keratinocytes using short hairpin RNA and performed phosphoproteomic analysis, which showed downregulation of the AKT signalling pathway, confirmed using Western blotting to phospho-AKT and immunostaining of biopsies from patients with AE. Given that AKT signalling is increased in acne vulgaris, we hypothesized that loss of FLG may protect patients with AE from acne. The Tower Hamlets Eczema Assessment (THEA) study is a cross-sectional study that aims to phenotype and genotype 1000 Bangladeshi children and young adults with AE. So far, 620 participants have undergone genotyping, 37% of whom have LoF mutations in FLG. We selected patients from this cohort who were older than 12 years of age. In total, 204 patients (99 FLG wild type, 86 heterozygotes, 19 compound heterozygotes) were included. We identified a diagnosis of acne or previous prescription of topical acne therapies or tetracycline antibiotics from the patients’ general practice e-health records. We stratified the patients by genotype, Eczema Area and Severity Index (EASI) score, Patient Oriented Eczema Measure (POEM) score, transepidermal water loss (TEWL) and palmar hyperlinearity groups. The χ2-test was used to determine differences between groups. A lower proportion of patients with AE with FLG mutations had acne (27% wild type vs. 19% FLG mutations), which was more pronounced, but not statistically significant, in the compound heterozygote group (16%). We saw a nonsignificant reduction in acne in patients who had the top 25% of TEWL measurements, those with the most severe form of hyperlinearity and those with higher POEM scores. Patients with severe AE, measured as an EASI score > 21, had a more reduced incidence of acne than those with lower EASI scores (9% vs. 26%; P = 0.04). Overall, this suggests that patients with more severe AE are protected from developing acne. There was insufficient evidence to establish if this was mediated by a reduction in filaggrin (FLG) and AKT signalling. This may be because the groups were too small to determine this. Given that all patients with severe AE have reduced FLG expression regardless of genotype, it is possible that this is mediated through FLG–AKT signalling.

Clinical Efficacy of Topical or Oral Soy Supplementation in Dermatology: A Systematic Review.

Soybean, a legume native to Southeast Asia, serves many nutritional and medical purposes due to its rich source of phytochemicals and its antioxidant activity. Many animal and in vitro studies have demonstrated its potential impact on dermatologic health. The objective of this review is to investigate the clinical response of soy-based oral supplementation or topical application on dermatologic outcomes. A systematic review of studies assessing soy supplementation or application was performed in January 2023. Databases included PubMed, Embase, Cochrane, and Natural Medicines, and studies assessing any formulation that included soybean or associated products were included. Thirty studies met the inclusion criteria and are included in the review; 13 of these studies assessed oral supplementation and 17 assessed topical application. Topical and oral supplementation demonstrated efficacious results for a variety of dermatologic parameters, including chronological or photoaging parameters, skin barrier status, hydration, hyperpigmentation, dermal network composition, erythema, hair and nail parameters, acne lesion counts, and vulvar lichen sclerosis scores. Factors associated with aging, such as wrinkle area and depth, were most frequently assessed among the studies, and both topical and oral studies demonstrated efficacy. Effects are likely mediated by dermal compositional changes, such as increased collagen and/or elastic fiber numbers. Transepidermal water loss measurements, an indicator of skin barrier status, were frequently obtained among the studies, although improvement was more likely achieved with topical application compared to oral supplementation. The results of this review highlight the utility of soy-based products for a variety of dermatologic applications, although future studies are required to determine optimal formulations and application routes for intended outcomes.

Calcitriol, an Active Form of Vitamin D3, Mitigates Skin Barrier Dysfunction in Atopic Dermatitis NC/Nga Mice.

Atopic dermatitis and psoriasis are prevalent chronic inflammatory skin diseases that are characterized by dysfunctional skin barriers and substantially impact patients' quality of life. Vitamin D3 regulates immune responses and keratinocyte differentiation and improves psoriasis symptoms; however, its effects on atopic dermatitis remain unclear. Here, we investigated the effects of calcitriol, an active form of vitamin D3, on an NC/Nga mouse model of atopic dermatitis. We observed that the topical application of calcitriol decreased the dermatitis scores and epidermal thickness of NC/Nga mice with atopic dermatitis compared to untreated mice. In addition, both stratum corneum barrier function as assessed by the measurement of transepidermal water loss and tight junction barrier function as evaluated by biotin tracer permeability assay were improved following calcitriol treatment. Moreover, calcitriol treatment reversed the decrease in the expression of skin barrier-related proteins and decreased the expression of inflammatory cytokines such as interleukin (IL)-13 and IL-33 in mice with atopic dermatitis. These findings suggest that the topical application of calcitriol might improve the symptoms of atopic dermatitis by repairing the dysfunctional epidermal and tight junction barriers. Our results suggest that calcitriol might be a viable therapeutic agent for the treatment of atopic dermatitis in addition to psoriasis.

Transepidermal water loss in allergic diseases

Background: In recent years, the epithelial barrier hypothesis has been emphasized in the formation of allergic diseases. Transepidermal water loss (TEWL) occurs through diffusion and evaporation from the skin to the external environment. There are few studies on TEWL in allergic diseases. Objective: This study evaluated the relationship between patients with atopic diseases and healthy controls and hygiene habits in TEWL. Methods: The study was conducted on patients who were followed up for atopic disease (asthma, allergic rhinitis, immunoglobulin E mediated food allergy, and atopic dermatitis) and healthy children. TEWL measurement was in a room that was stable in terms of humidity and temperature by using a widely validated open room system. During the measurement, the participants reported their frequency of taking a shower and cleaning product use. Results: In the study group, TEWL was measured in 182 patients, and the median (min-max) TEWL was 21.3 g/hm² (7.8-101.3 g/hm²) in the disease group and 9.6 g/hm2 (3.9-30.3 g/hm²) in the control group (p < 0.001). The number of weekly baths was higher in the disease group (p < 0.001). The cutoff for atopic diseases was 13.2 g/hm² (sensitivity, 83.2%; specificity, 84.3%; p < 0.001). Conclusion: High TEWL in atopic diseases supports the epithelial barrier hypothesis associated with disease development. Further studies are necessary to determine the threshold between healthy controls and the patients in the disease group. The TEWL measurement can be an effective method to determine the risk groups. Moreover, further studies related to factors on TEWL and treatment methods to reduce this loss are necessary, too.

Systematic investigation of factors, such as the impact of emulsifiers, which influence the measurement of skin barrier integrity by in-vitro trans-epidermal water loss (TEWL)

Trans-epidermal water loss (TEWL) has been the most widely used method to assess the integrity of the skin barrier and evaluate the irritation potential or the protective properties of topical products for many years. It detects the amount of water that diffuses across the stratum corneum (SC) to the external environment. As one of the most important functions of the skin is to keep water inside the body, an increase in TEWL is used to indicate the skin’s impaired barrier function. So far, a variety of commercial instruments are available to measure the TEWL. Their applications mainly focus on the in-vivo TEWL measurements for dermatological examinations or formulation development. Recently, an in-vitro TEWL probe has also been commercially released enabling preliminary tests with excised skin samples. In our study, we first aimed to optimize the experimental procedures for detecting the in-vitro TEWL of porcine skin. Secondly, different kinds of emulsifiers were applied to the skin, including polyethylene glycol-containing emulsifiers (PEG-ylated emulsifiers), sorbitan esters, cholesterol, and lecithin. Sodium lauryl sulfate (SLS) was used as a positive control, and water as a negative control. Based on the findings, we established a protocol for accurately measuring the in-vitro TEWL values, emphasizing that the temperature of the skin sample should be constantly maintained at 32℃. Subsequently, the influences of emulsifiers on the in-vitro TEWL were analyzed. They indicated a significant skin barrier impairment of PEG-20 cetyl ether, PEG-20 stearyl ether, and SLS on in-vitro skin. Furthermore, we interestingly found that there consistently was an alteration of the TEWL values, even after the application of water to the skin. Our findings are of special interest, as the European Medicines Agency (EMA) recommends the use of in-vitro TEWL to determine skin barrier intactness during Franz cell experiments. Thus, this study provides a validated protocol for measuring the in-vitro TEWL and elucidates the impact of emulsifiers on the skin barrier. It also improves the understanding of tolerable variations of in-vitro TEWL and offers recommendations for its use in research.

Effects of impermeable and semipermeable glove materials on resolution of inflammation and epidermal barrier impairment after experimental skin irritation.

Semipermeable membranes might be suitable for glove liners or comfort gloves in individuals with irritant contact dermatitis (ICD). To evaluate the effects of different glove materials on inflammation and epidermal barrier impairment after experimental skin irritation. Nine test areas on the volar forearms of 24 healthy volunteers were irritated with sodium lauryl sulfate (1%) and afterward covered for 6 days (6 or 8 h/day) with semipermeable Sympatex (SYM), vinyl (OCC), combinations of vinyl with Sympatex (SYM/OCC) or cotton (COT/OCC), or left uncovered (CON). Up to day 10, measurements of transepidermal water loss (TEWL), erythema (a*), skin humidity (SH) and visual scoring (VS) were applied. No significant differences in skin parameters were found between COT/OCC and SYM/OCC as well as between each of the combinations and CON. SYM, COT/OCC and SYM/OCC led to better results for most skin parameters than OCC alone. Occlusive material has a negative impact on skin barrier recovery and inflammation after skin irritation whereas SYM is not inferior to uncovered areas indicating good tolerability. Altogether, the data suggest that SYM is a useful alternative to COT as material for glove liners and comfort gloves in ICD patients.

In vivo transepidermal water loss: Validation of a new multi-sensor open chamber water evaporation system Tewameter TM Hex.

Instrumentation technology for transepidermal water loss measurements has not been substantially modified since its introduction by Nilsson in 1977. Recent progress in sensor development allowed a new sensor arrangement using a matrix of 30 sensors. Raw measurement values are processed with spatial statistical analysis. We aimed to compare the new, multi-sensor probe (Tewameter TMHex) with the established Tewameter TM300 probe and to gain reference data for the new parameters of transepidermal energy loss and water vapor concentration on skin. Baseline measurements and repeated measurements on the volar forearm and assessment on eight different anatomical locations were performed on 24 healthy volunteers (both gender) with the TMHex and the TM300. A significant correlation (p<0.001; R-coefficient=0.9) between TMHex and the TM300 with a low coefficient of variance (CV) 11% for TMHex and 19% for TM300, could be assessed. The CV ranged between 7% (right inner upper arm) and 14% (palms). Average transepidermal heat loss ranged from 12W/m2 on the lower leg to 38.8W/m2 on the palm. The correlation between TMHex and TM300 along with the robustness of the measurements with the TMHex shows that the new probe for assessment of epidermal barrier function is comparable to the TM300. In most conditions, TMHex provides more accurate measurements than TM 300. New parameters open the field to studying skin's water and energy balance.