Impact of ultraviolet radiation and ozone on the transepidermal water loss as a function of skin temperature in hairless mice

Exposure to ultraviolet radiation or ozone leads to skin damage including oxidation of skin biomolecules, as well as to depletion of constitutive antioxidants. The highly organized stratum corneum forming the main barrier against most xenobiotics is particularly susceptible to such damage and possible barrier perturbation may be the consequence. Whereas ample evidence exists for an increased permeability for different solutes including water after exposure to ultraviolet radiation, such an effect has not yet been reported for ozone. This study reports on the effect of such oxidative stressors using the hairless mouse as the skin model and measuring temperature-controlled transepidermal water loss (TEWL) as an indicator for skin barrier integrity. First, a strong dependency of the TEWL on skin temperature was observed, an effect that was clearly more pronounced than that found in man. Given this temperature dependency in untreated animals, we proceeded to determine the effects of both ultraviolet radiation and ozone on TEWL over a relevant physiological skin temperature range. Solar-simulated ultraviolet radiation (0.75-3 minimal erythemal dose) resulted in a delayed and dose-dependent skin barrier disruption over the entire temperature range investigated. Conversely, daily ozone exposure at 2 ppm for 1 week, however, did not significantly alter TEWL up to 72 h after the last exposure. The results demonstrate a differential response of the epidermis to two environmental stressors associated with oxidative damage; they suggest that chronic ozone exposure at relevant environmental levels does not lead to a detectable skin barrier defect, while solar UV exposure was demonstrated to increase epidermal water loss. Furthermore, experimental evidence clearly suggests that future studies applying TEWL measurements in animal models should be performed under carefully controlled skin temperature conditions.     

The effect of prolonged drying on transepidermal water loss, capacitance and pH of human vulvar and forearm skin

The effect of prolonged drying on transepidermal water loss (TEWL), capacitance and pH of vulvar and forearm skin was studied in 15 healthy female volunteers. A desiccation chamber that absorbed water evaporating from the skin surface was applied to the forearm and labia majora skin daily for 4 days. Skin TEWL, capacitance and pH were measured daily and 4 days after removal of the desiccation chamber at the site of drying and at a symmetrical control site. Under desiccation, TEWL both of forearm and of vulvar skin showed an increase during the first days of drying, followed by a gradual decrease. After 4 days of drying, forearm TEWL was reduced to 91% of the control value, without reaching significance. Vulvar TEWL was significantly reduced to 80% of the control value. Although relative reduction of vulvar TEWL was higher than that of forearm TEWL, the absolute of value of vulvar TEWL after drying remained significantly higher than that of forearm TEWL. Skin capacitance significantly decreased under drying both in forearm and vulvar skin. Skin pH was significantly reduced by drying at the vulva, but not at the forearm. It is concluded that although changes in physiological parameters during drying seem to be more pronounced in vulvar than in forearm skin, differences suggest that the specific properties of vulvar skin are not explained by anatomically related occlusion alone.     

Skin permeability barrier and occlusion: no delay of repair in irritated human skin *

It has been reported that occlusive treatment of irritated skin results in a reduction of barrier repair activities in hairless mice. In contrast, the clinically observed benefit of occlusion in the treatment of hand eczema and other chronic skin diseases with a perturbed barrier function is well–known. While the beneficial effect of occlusion has been proven for the treatment on psoriasis there are no controlled clinical studies of the effect of occlusion on irritated human skin. We have therefore evaluated the effect of various occlusive treatments on repair of the human skin permeability barrier under controlled experimental conditions. Barrier perturbation was induced either by application of sodium lauryl sulfate (SLS) or by repeated tape stripping. This was followed by treatment with different occlusive and semipermeable dressings, partly alter pre-treatment with petrolatum. Repair of water barrier function was evaluated by daily measurements of transepidermal water loss (TEWL) for 1 week. SLS irritation and tape stripping led to a 6-fold increase in TEWL as a sign of severe water barrier perturbation, followed by a stepwise decrease over the following days. Occlusion did not significantly delay barrier repair as measured by TEWL. Only in tape-stripped skin did TEWL stay at high levels during treatment with self-adhesive dressings. This may be explained by damage of newly formed stratum corneum caused by changing of these membranes. Our results indicate that, in contrast to earlier observations in hairless mouse skin, permeability barrier repair activities are not significantly delayed by occlusive treatment in human skin.     

Silk sericin as a moisturizer: an in vivo study

Background Excessive transepidermal water loss (TEWL) is the one of the causes of dry skin, and skin moisturizers have been used to overcome it. Aim The purpose of this research was to study the moisturizing effect of sericin, a silk protein. Because silk sericin has resemblance with the natural moisturizing factor (NMF), it has been studied for its application in skin cosmetics. Methods Sericin gels were prepared using sericin solution and with pluronic and carbopol as stabilizers. The gels were applied on the skin of healthy human volunteers and its moisturizing efficiency was evaluated by measuring the skin hydroxyproline content, impedance, TEWL, and scanning electron microscopy (SEM) results. Results Decrease in skin impedance, increase in hydroxyproline level, and hydration of epidermal cells revealed the moisturizing effect of sericin, whereas decrease in the value of TEWL may be attributed to occlusive effect, which prevents water loss from the upper layer of the skin. Skin surface topography revealed the smoothness of the upper layer of the skin as a result of moisturization. Conclusion Increase in the intrinsic moisturization of skin by sericin may be attributed to restoration of the amino acids and its occlusive effect. Thus, it would become a promising and important moisturizing ingredient in moisturizing formulations.     

The water barrier function of the skin in relation to the water content of stratum corneum, pH and skin lipids. The effect of alkaline soap and syndet on dry skin in elderly, non-atopic patients

Clinical dryness of the skin is a common problem among elderly, dermatological patients. In the present investigation, hydration, surface lipids, skin pH and water barrier function as expressed by the transepidermal water loss (TEWL) were studied in both dry and normal skin. Using these parameters, a comparison of the local effects of acid and alkaline cleansing products was made. In non-atopic elderly patients with dry skin, the TEWL values were lower than in the younger control group but higher than in the older controls. Following one week's topical therapy, the TEWL values in the patient group decreased further and approached the lower values of the older control group. At the same time the skin hydration values increased, indicating a beneficial effect on the skin barrier. An inverse relationship was demonstrated between TEWL and skin hydration. The study indicates that high TEWL values are frequently correlated with high pH, low hydration of the stratum corneum and reduced skin surface lipid content. Despite the intensive use of an acid syndet and lotion, the pH-readings increased but were still within the 'confidence limits' of the control groups.     

Cosmetic formulations containing <Emphasis Type="Italic">Lithospermum erythrorhizon</Emphasis> root extract show moisturizing effects on human skin

Retention of water in the stratum corneum of skin epidermis plays an important role in regulation of skin function. Loss of water may decline skin appearance gradually and lead to irregular skin disorders. The root extract of Lithospermum erythrorhizon (LES) is known for its various pharmacological activities. However, the potential skin care effect of LES is not clear. The aim of this study was to evaluate the moisturizing efficacy and skin barrier repairing activity of LES. For this study, 30 healthy Asian females (age 20-30) with healthy skin had applied the test emulsions twice daily over a period of 28 days. The skin properties were measured by skin bioengineering techniques. Our preliminary results indicated that LES show moisturizing effect on skin hydration in a time- and dose-dependent pattern, and the maximum increase in skin humidity was 11.77 +/- 1.18% for emulsion LES5.00. Particularly, LES-containing emulsions significantly improve skin barrier function by decreasing the value of transepidermal water loss (TEWL) in a time- and dose-dependent pattern, and the maximum decrease in TEWL value was 7.68 +/- 0.79% for emulsion LES5.00. Taken together, our data demonstrate that LES is more effective in increasing skin humidity and decreasing the TEWL values, indicating the potential skin care effects of LES.     

The influence of repeated exposure to surfactants on the human skin as determined by transepidermal water loss and visual scoring

The purpose of this study was to develop a new model for the induction of chronic irritant contact dermatitis, which would reflect well the conditions of daily practice. Various weak irritant agents were tested for irritating potency on the skin and the sensitivity of transepidermal water loss (TEWL) measurements in the detection of early skin changes was also studied. 10 widely used surfactants and 1 solubilizer were applied to the skin of the forearms of healthy volunteers in aqueous solutions of 12.5 millimoles/l for 45 min twice daily for 3 weeks. The effect on the skin was evaluated daily by means of TEWL measurements and by a visual scoring system. Each solution caused an increase in TEWL value over time due to the cumulative irritating action on the epidermal barrier. This increase in TEWL was different for the various solutions, resulting in different mean TEWL values on the last day of the experiment. Thus, it was possible to rank the agents according to irritating potency. This ranking order was the same in almost every individual and remained constant during the 3 weeks. In comparison with the visual scoring system, the TEWL measurements were more sensitive in the detection of early changes in the skin.     

Protection effect of cosmetics on human skin under simulated rigorous environment.

BACKGROUND/PURPOSE: The efficacy of cosmetics on human skin measured under normal mild laboratory environment might be discounted by exterior environment factors such as wind, UV exposure, etc. Few studies have focused on the 'genuine' efficacy of cosmetics on human skin during exposure to external rigorous environment. The aim of this study was to develop a model for the evaluation of the efficacy of cosmetics on human skin under simulated rigorous environment. METHODS: We measured skin water content and transepidermal water loss (TEWL) before and after products application under simulated windy and sub-erythema UV exposure treatment in a constant temperature and humidity laboratory. RESULTS: The results showed that the products had higher water content and lower TEWL at 2, 4 and 8 h of products application, and ameliorated the skin moisturization situation after a 3-week continuous use of the products. In addition, the products might protect the skin to maintain the normal water content and TEWL under the simulated windy or sub-erythema UV exposure treatment in our laboratory when compared with untreated area. CONCLUSION: Our data indicate that this model may provide a more accurate evaluation for the genuine moisturizing effect of cosmetics under external natural climate.     

Correlation of transepidermal water loss with skin barrier properties in vitro: comparison of three evaporimeters

Aim: This study investigates the relationship between transepidermal water loss (TEWL) and skin permeability to tritiated water as a rapid assessment of the integrity of the barrier properties of skin as part of in vitro skin permeation studies.
Methods: TEWL values before and during the experimental period were measured using three evaporimeters (A, B, and C) representing different measuring principles and technologies. Single application of tritiated water was dosed on dermatomed human skin samples in a flow-through diffusion cell system. Radioactivity of the absorbed dose and the removable dose residues was counted to determine percent dose and flux rate. These data were further combined with TEWL values to analyze the correlation.
Results: Evaporimeter C, a closed chamber–condenser technology, had higher measurement capacity than other instruments, evaporimeter A, an open chamber, and evaporimeter B, a closed chamber ( P <0.001). The baseline TEWL value correlated with tritiated water flux ( r =0.34, P =0.04). The pattern of tritiated water expressed as percent dose permeated into receptor fluid was similar to that of TEWL values.
Conclusion: These data indicate that TEWL can be ascribed to be a measure of skin water barrier function. Further work should be conducted to interpret the significance of measuring TEWL by evaporimetry.     

Transepidermal water loss after photodynamic therapy, UVB radiation and topical corticosteroid is independent of inflammation

Background/purpose: Photodynamic therapy (PDT) and ultraviolet radiation cause an inflammatory reaction of the skin. This may lead to disruption of the skin barrier function. We examined the acute effect of PDT and short-wave ultraviolet radiation (UVB) on the barrier function of the epidermis. Furthermore, we explored the effect on the skin barrier of topical corticosteroid previous to UVB exposure.
Methods: Eight patients with acne vulgaris of the face were treated with PDT two times, and eight patients were left untreated. The transepidermal water loss (TEWL) was measured before treatment and at three control visits after PDT over 12 weeks. Twenty healthy volunteers were irradiated with UVB in two areas on the back. One area was treated with topical high-potency corticosteroid before irradiation. TEWL was measured before, 15 min and 24 h after UVB exposure.
Results: TEWL did not differ significantly between the various visits in each acne group and no significant difference in the TEWL between PDT-treated patients and the control group was found at any visit ( P >0.05). TEWL was not significantly altered 15 min and 24 h after a single exposure to UVB and no positive relationship was found between UV-induced erythema and change in TEWL ( P >0.05). Application of topical corticosteroid before UVB did not affect the skin barrier function significantly ( P >0.05).
Conclusion: Neither PDT nor a single exposure to UVB damaged the permeability barrier function of the skin and no effect on the TEWL was found when topical corticosteroid was applied previous to UVB irradiation.     

Baseline transepidermal water loss (TEWL) as a prediction of susceptibility to sodium lauryl sulphate

The rôle of different factors in the susceptibility of the skin to weak irritants was studied by means of multiple linear regression models. The skin of 37 healthy subjects was exposed to a solution of sodium lauryl sulphate of low molarity 2 × daily for 4 days. The condition of the skin was evaluated by transepidermal water loss (TEWL) measurements on the 1st day (before exposure, TEWL1) and on the 5th day of exposure (TEWL5), and by a visual scoring system. The TEWL5 value was strongly related to the TEWL1 value (R = 0.71). The influence of such factors as history of mucosal atopy, history of sensitivity to soap, dry skin, skin type, sex and age on the TEWL5 value was negligible. The baseline TEWL level (TEWL1) might be a reliable indication of an individual's susceptibility to weak irritants.     

Biophysical measurements of human forearm skin in vivo: effects of site, gender, chirality and time

Background/aims: Measurements of transepidermal water loss (TEWL) and skin colour are biophysical techniques commonly used to measure the in vivo skin effects of cosmetics, topical medicaments and chemical irritants. The purpose of this study was to investigate the variability of TEWL and skin colour on human forearm skin as a function of regional variation, gender and preferred chirality over an 8 h period.
Methods: Biophysical measurements of TEWL and skin colour were made at five sites on both forearms of male ( n =8) and female ( n =9) human volunteers in vivo (38% relative humidity, 21°C).
Results: Rates of TEWL at the forearm midpoint were 10% lower than at the forearm extremities ( P <0.01). Skin redness ( a *) near the wrist was 5–10% higher than at other sites ( P <0.05). Rates of TEWL were 5% higher in male volunteers ( P <0.05). Red and blue ( b *) colour measurements of male forearm skin differed by 18% and 20% in comparison with female, respectively. Rates of TEWL, skin brightness ( L *) and b * decreased by 9% ( P <0.05), 1.8% ( P <0.05) and 4% ( P <0.05), respectively, with time whereas a * and skin temperature increased by 4.5% ( P <0.01) and 7.2% ( P <0.01), respectively. There was a significant correlation between the change in all measured parameters with time.
Conclusions: Significant differences in TEWL and skin colour were identified that may have relevance in the design and interpretation of multivariate analyses of human forearm skin. Diurnal variation of TEWL, skin colour and temperature may have a single underlying mechanism.     

Hydration studies on scaly hand eczema

Transepidermal water loss (TEWL) and electrical conductance by a high-frequency (3.5 MHz) method were measured in 20 patients with chronic scaly hand eczema. Eczematous skin was compared with uninvolved skin of the same anatomical region. TEWL of eczematous skin was increased in all patients. In contrast, the conductance was decreased in all patients except for one, who showed equal values in pathological and uninvolved skin. This indicates that the water-holding capacity of eczematous skin is reduced. There was no correlation between clinical grading of scaling, and TEWL and electrical conductance. TEWL and conductance were not correlated, and the 2 methods are therefore supplementary for assessment of eczema and scaling. TEWL may be useful for monitoring the primary effect of therapy, and conductance for the final documentation of healing.     

非磨削型嫩肤激光对小鼠皮肤失水的影响

目的 研究非磨削型激光嫩肤对皮肤屏障功能的影响.方法 用CooltouchⅡ 1320nm激光、Gentlelase755nm激光、Vbeam595nm激光、GentleYAG1064nm激光照射小鼠皮肤.并用1%透明质酸钠涂抹于GentleYAG 1064nm激光照射后的皮肤,观察1周内皮肤经表皮失水、含水量的变化.结果 激光照射小鼠皮肤1h时就出现了经表皮失水较正常对照组显著性增高(P<0.05),595nm激光照射引起的皮肤经表皮失水值增高在激光照射后的第7天恢复正常(P>0.05).1320nm激光在第2天时恢复正常(P>0.05),1064nm激光在第4天恢复正常(P>0.05),755nm激光在第4天恢复正常(P>0.05).GentleYAG1064nm激光照射部位的皮肤每天用1%透明质酸钠涂抹1次后,经表皮失水值在第4天恢复正常(P>0.05).结论 各种非磨削型嫩肤激光照射小鼠背部皮肤后均引起局部皮肤经表皮失水增加,24h内均未能恢复正常,但是在1周时均可基本恢复正常.波长较短的595nm激光引起的经表皮失水恢复较慢,而波长较长的1320nm激光引起的经表皮失水恢复较快.激光照射后外用1%透明质酸钠无助于皮肤经表皮失水的恢复.     

In vitro transepidermal water loss: differences between black and white human skin

In vivo transepidermal water loss studies are characterized by large inter-individual variability and biased by environmental effects and eccrine sweating. An in vitro technique for measuring transepidermal water loss (TEWL) was used to compare TEWL in two racial groups--blacks and whites. In both groups a significant correlation between skin temperature and increased TEWL was found (P less than 0.01). Furthermore, black skin had a significantly higher mean TEWL than white skin, corrected log TEWL 2.79 and 2.61 micrograms/cm2/h, respectively. The difference in TEWL between the groups could because measurements were made in the absence of eccrine sweating and other vital functions. The higher TEWL in black skin could be explained on the basis of a thermoregulatory mechanism. The anatomical and physiological differences in the stratum corneum between different races are discussed.     

Orally administered ethanol: transepidermal pathways and effects on the human skin barrier

Ethanol intake is associated with a variety of skin diseases. The aim of the present study was (1) to identify the pathways of release of orally administered ethanol through the skin, and (2) to investigate the effects of a single oral dose of ethanol on the penetration of topically applied substances into the skin. Ethanol evaporation via the skin was measured using the new technique of ion mobility spectrometry (IMS). Transepidermal water loss (TEWL) and skin surface temperature were simultaneously measured before and after ethanol consumption. Measurements were performed on skin sites with different stratum corneum (SC) thickness, and density of follicles and sweat glands. These appendages were selectively sealed to investigate their participation in ethanol evaporation. The penetration of a topically applied UV filter substance was studied before and after ethanol consumption after removing the SC with adhesive tape. Ethanol evaporation was measured within 5 min of consumption, while the skin surface temperature remained nearly constant. The sealing of the appendages did not have a significant effect on ethanol evaporation. On the forehead, a higher TEWL value was measured than on the forearm. On both skin sites, an increase in TEWL was observed after ethanol ingestion. No influence of orally administered ethanol on the penetration of the topically applied UV filter substance was observed. The results indicate that ethanol evaporation occurs via the lipid layers without a significant effect on the penetration of the topically applied substance.     

经表皮水分流失与皮肤屏障的遗传学研究

经表皮水分流失（Transepidermal water loss?,TEWL）测量的是水分从真皮和表皮的水合层向皮肤表面扩散的通量密度,是用于评估皮肤屏障功能的一项成熟无创的方法,最新的一项研究发现TEWL值与9号染色体9q34.3基因突变密切相关,本文总结了TEWL与皮肤屏障功能的遗传学研究进展。     

Skin barrier function and dermal inflammation. An experimental study of transepidermal water loss after dermal tuberculin injection compared with SLS patch testing

The reaction of the skin water barrier to dermal inflammation was studied in 15 healthy volunteers. Dermal inflammation was induced either by injection of tuberculin (Mantoux test) or by a 24-h sodium lauryl sulphate (SLS) patch test on the volar forearm. Measurement of transepidermal water loss (TEWL) was used for evaluation of the skin barrier function. Inflammation was quantified by assessment of blood flow by laser-Doppler flowmetry. Measurement from uninvolved skin in the test region > 7 cm distant from the test sites served as control. Measurements were performed twice, separated by an interval of 6 days. Throughout the study. TEWL values were higher in the SLS test sites than in the Mantoux reactions, although the blood flow was significantly increased in Mantoux reactions compared with SLS test sites. This indicates that the impaired skin barrier function caused by SLS is due to a direct cytotoxic effect, and TEWL were significantly higher on the arm with the Mantoux test than the arm with SLS patch test. The significant inflammation caused by the Mantoux reaction may cause functional alterations in the clinically normal skin > 7 cm distant from the test area.     

The effect of bilayer and hexagonal H(II) phase lipid films on transepidermal water loss

The common membrane phospholipids tend to adopt either the familiar bilayer phase or the less familiar hexagonal H(II) phase when isolated and hydrated in excess water. The objective of this study was to compare the effects of these very different macroscopic lipid structures on transepidermal water loss (TEWL) when they are applied to the surface of pig skin mounted in Franz diffusion cells. First, a novel in vitro method for monitoring TEWL was developed and characterized in which the flux of water from the subphase through skin was measured through the absorption of (3H)-water by lyophilized polyethylene glycol (PEG) mounted above the skin surface. TEWL was varied by disrupting the skin barrier to different degrees by tape stripping or solvent extraction. Bilayer-forming egg phosphatidylcholine (EPC) or hexagonal H(II)-forming dioleoyl phosphatidylethanolamine (DOPE) were applied topically as solutions in ethanol and subsequently dried to films. The molecular configuration adopted by each lipid at the skin surface was confirmed by phosphorus NMR. TEWL for normal skin was approximately 2 g H2O/h/m2, increasing to a maximum of 80 g H2O/h/m2 after the stratum corneum was completely removed by tape stripping. On tape-stripped skin, films of lipid doses as low as 10 mg/cm2 significantly reduced TEWL, and DOPE (hexagonal H(II)) was approximately twofold more effective than EPC (bilayer). Furthermore, the effects of EPC and Vaseline on reducing TEWL from damaged skin were readily reversed by a simple aqueous wash, whereas the DOPE effect was unaltered even by vigorous washing. Similar results were obtained with lipid films applied to solvent-extracted skin. The data are consistent with the formation of extensive hydrophobic interactions between the skin and the outwardly facing acyl chains of the inverted, hexagonal H(II) phase adopted by DOPE. This results in the formation of a durable surface barrier capable of significantly reducing TEWL from damaged skin.     

Comparison of barrier function and lipids in psoriasis and essential fatty acid-deficient rats

Elevated rates of transepidermal water loss (TEWL) in plaques of human psoriasis and in the skin of essential fatty acid (EFA)-deficient rats were compared. Cutaneous application of sunflower seed oil to EFA-deficient rats lowered the rate of TEWL to normal, healed the characteristic scaly skin of this condition and increased the incorporation of linoleic acid of the sunflower seed oil into epidermal phospholipid. Application of sunflower seed oil to psoriatic skin did not lower the TEWL, nor produce clinical improvement, but the linoleic acid of epidermal phospholipid was increased. Local application of a steroid ointment, clobetasol propionate (Dermovate) reduced the elevated TEWL in psoriasis and produced clinical improvement, but had no effect upon skin or plasma lipids. Application of this steroid to EFA-deficient rat skin cleared the skin scaliness but did not restore barrier function or change the composition of the skin lipids. It is concluded that the impaired barrier function in psoriasis is not due to EFA-deficiency.