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.     

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。     

面部糖皮质激素依赖性皮炎患者经皮水分丢失和皮肤含水量分析

目的 分析面部糖皮质激素依赖性皮炎患者的皮肤屏障功能。方法 将面部分为额部、鼻尖、下颌、双面颊、双侧口角的皮损区及左耳后无皮损区共8个点，分别测量95例面部糖皮质激素依赖性皮炎患者及25例健康对照者的经皮水分丢失（TEWL）和皮肤含水量。结果 与健康组相比，面部糖皮质激素依赖性皮炎组下颌、双侧口角、双面颊TEWL值均显著升高（t值分别为4.90，2.60，2.57，2.54，3.77，P < 0.01）；双侧口角、右面颊及额部的皮肤含水量均显著降低（t值分别为3.27，3.81，2.02，2.78，P < 0.05）。在8个测量点中，面部糖皮质激素依赖性皮炎组与健康组TEWL值均为下颌及双侧口角 > 双面颊及额部 > 耳后无皮损区；皮肤含水量降低均为下颌及双侧口角 > 双面颊及额部 > 耳后无皮损区。结论 面部糖皮质激素依赖性皮炎患者下颌、双侧口角、双面颊区域皮肤屏障功能受损，口周区域TEWL值较高，而面颊皮肤水分含量较少。     

Basal transepidermal water loss, skin thickness, skin blood flow and skin colour in relation to sodium-lauryl-sulphate- induced irritation in normal skin

The influence of basal transepidermal water loss (TEWL), skin thickness, blood flow and skin colour on susceptibility to sodium-lauryl-sulphate(SLS)-induced irritant contact dermatitis was studied in 70 healthy volunteers. SLS 0.5% was applied as a patch test. For assessment of basal values and skin response to SLS, bioengineering methods were used: TEWL was measured by an evaporimeter, skin thickness by ultrasound A-scan, blood flow by laser Doppler flowmetry, and skin colour by a colorimeter, using the L*a*b* system of the Commission Internationale de l'Eclairage (CIE). By use of multiple regression analysis, it was demonstrated that basal TEWL was substantially related to skin susceptibility to SLS, high basal TEWL predicting an increased susceptibility to SLS. Also increased light reflection from the skin, indicating a 'fair' skin, was found to be associated with increased susceptibility to SLS.     

经皮水分丢失与健康人性别、年龄、解剖部位的关系

通过经皮水分丢失（TEWL）来评价皮肤的屏障功能，并研究经皮水分丢失与性别，年龄，解剖部位的关系，参加本次实验的为健康志愿者共104名，其中女性53名，男性51名，分为5个不同年龄组，用与计算机相连的蒸发测定仪Darmalab TEWL探头测量。结果发现不同年龄组男女性别之间TEWL值均无显著性差异（P＞0．05），新生儿组TEWL值明显高于其他各年龄组（P＜0．05），老年组TEWL值低于其他年龄组。在8个不同部位测量中，经统计得到TEWL值顺序为：手掌＞额部＞颊部＝手背＞小腿＝背部＞前臂＝胸部。说明TEWL与性别无明显相关性，而与年龄相关，以新生儿最高，老年人最低，在身体各部位的测量中，四肢末端和暴露部位经皮水分丢失较高。     

Transepidermal water loss, temperature and sebum levels on women's facial skin follow characteristic patterns

Background/aims: The aim of this study was to compare the biophysical properties of different facial zones. Methods: We investigated transepidermal water loss (TEWL), skin temperature and sebum casual level (CL) on 90 adjacent test sites distributed on the forehead, cheeks and chin of five women. Results: All three parameters showed a symmetrical distribution around the facial median line. Only minor variations of individual values were found within the forehead and the chin areas. In contrast, the cheeks exhibited a distinct gradient with highest values in the paranasal zones and lowest on the cheek bones for all of the three parameters. The mean values on both cheeks of a given individual were nearly identical, and the patterns within the two cheeks were superimposable. Both CL and skin temperature distributions pointed out a “T‐zone” with highest values on the forehead, on the chin and on the median part of the cheek. Conclusions: Our data demonstrate that biophysical skin properties differ considerably between different facial areas but that they follow a characteristic distribution.     

Changes in transepidermal water loss and cutaneous blood flow during the menstrual cycle

This study quantified irritant susceptibility and blood vessel reactivity in normal women over the course of the menstrual cycle. Such alterations were studied by observing vasodilation from topical application of methyl nicotinate (MN) on the following days of the menstrual cycle: (i) the day of putative maximal estrogen secretion; (ii) the day of maximal progesterone secretion; (iii) the day of minimal estrogen/progesterone secretion. These responses were evidenced by changes in the following dose response characteristics: the initial response (IR), the peak response (PR) and the area under the curve (AUC). Baseline laser Doppler velocimetry (LDV) blood flow values and transepidermal water loss (TEWL) values on normal skin were also obtained. No significant differences existed for any of the dose-response characteristics (IR, PR, AUC) when the values for the 3 testing days were compared to one another. Significant differences did exist for baseline TEWL values when comparing the day of maximal estrogen secretion to the day of minimal estrogen/progesterone secretion. TEWL was higher on the day of minimal estrogen/progesterone secretion as compared to the day of maximal estrogen secretion on both back (p = 0.037) and forearm (p = 0.021) sites, suggesting that the skin barrier function is less complete on the days just prior to the onset of the menses as compared to the days just prior to ovulation. Significant differences in baseline blood flow also existed for the day of maximal estrogen secretion as compared to the day of maximal progesterone secretion, with higher baseline blood flow recorded on the day of maximal progesterone secretion on both the back (p = 0.021) and forearm (p = 0.009) sites.     

Time course of occlusive effects on skin evaluated by measurement of transepidermal water loss (TEWL) Including patch tests with sodium lauryl sulphate and water

The time course for transepidermal water loss (TEWL) for a period of 3 h after removal of occlusive patch tests with sodium lauryl sulphate (SLS), water and empty chambers was studied in healthy volunteers. Patches were applied to the upper arm for 24 h, TEWL was measured immediately after removal of the patches, and every 30 min up to 3 h. For SLS and water patches, TEWL remained significantly increased for 3 h. as compared to normal adjacent skin, while for empty chamber patches. TEWL was only significantly increased for 30 min. A significant decrease from 0 to 30 min and from 30 to 60 min was observed for all patches, and for water patches, a significant decrease in TEWL was found from 60 to 180 min, while SLS patches remained constant. The prolonged increase in TEWL observed after SLS exposure is a well-known occurrence. The prolonged increase in TEWL after exposure to water is interpreted as transient damage to the water harrier of the skin.     

Artificial reduction in transepidermal water loss improves skin barrier function

BACKGROUND: Artificial reduction of abnormal transepidermal water loss (TEWL) is considered to improve skin diseases associated with a defective barrier function. Treatment of the skin with moisturizers is also known to influence skin barrier function. Whether or not differences in occlusion between creams contribute to their effects on the skin barrier function is unknown. OBJECTIVES: To investigate the long-term effects of a semipermeable membrane on the skin barrier function in normal skin. In addition, the occlusive properties of two creams were studied. METHODS: The study was randomized, controlled and evaluator-blind using measurement of TEWL and skin susceptibility to sodium lauryl sulphate as indicators of skin barrier function. RESULTS: Coating of the skin with a silicone membrane for 23 h per day for 3 weeks improved skin barrier function, whereas no significant changes were found after using the membrane for 8 h per day. CONCLUSIONS: Differences between creams in terms of their effect on skin barrier function cannot be solely explained by their occlusive properties.     

Do osmotic forces play a role in the uptake of water by human skin?

BACKGROUND/PURPOSE: To describe the water and ion transport through the skin under different conditions, we developed a three-component mixture model. This model has proven to describe the transient change in transepidermal water loss (TEWL) after a change in relative humidity and the result of damage to the skin. Osmotic forces arc present in the model. To assess the influence of osmotic forces on the water uptake of the skin, we investigated transient TEWL values after 1 h application of salt solutions of different molarities (0, 1, and 4 M NaCl). METHODS: Filters saturated with 0, 1, and 4 M NaCl solution were applied for 1 h under occlusion. TEWL was measured 50-90 min after removal of the solution. The transient water loss curves were fit with an exponential function. The area under the fitted curve was calculated and regarded as a measure for the amount of extra water absorbed in the skin. RESULTS: For all molarities, TEWL is increased immediately after removal of the solution. In time, this increase decays until pre-application values are reached again. The rate of decrease differs significantly for all three molarities. Ninety-five per cent of the increase has been reversed after 30, 19, and 6 min for the 0, 1, and 4 M case, respectively. The amount of water absorbed differs significantly between the three molarities 7.3+/-2.0; 3.9+/-1.0; 2.0+/-0.5 g/m(2), respectively. CONCLUSIONS: In all cases, there was an increase in TEWL immediately after removal of the solution. The significant differences in decay time and amount of water absorbed between the three molarities indicate that osmotic forces do play an important role in the water uptake.     

International guidelines for the in vivo assessment of skin properties in non‐clinical settings: Part 2. transepidermal water loss and skin hydration

Background

There is an emerging perspective that it is not sufficient to just assess skin exposure to physical and chemical stressors in workplaces, but that it is also important to assess the condition, i.e. skin barrier function of the exposed skin at the time of exposure. The workplace environment, representing a non‐clinical environment, can be highly variable and difficult to control, thereby presenting unique measurement challenges not typically encountered in clinical settings.

Methods

An expert working group convened a workshop as part of the 5th International Conference on Occupational and Environmental Exposure of Skin to Chemicals (OEESC) to develop basic guidelines and best practices (based on existing clinical guidelines, published data, and own experiences) for the in vivo measurement of transepidermal water loss (TEWL) and skin hydration in non‐clinical settings with specific reference to the workplace as a worst‐case scenario.

Results

Key elements of these guidelines are: (i) to minimize or recognize, to the extent feasible, the influences of relevant endogenous‐, exogenous‐, environmental‐ and measurement/instrumentation‐related factors; (ii) to measure TEWL with a closed‐chamber type instrument; (iii) report results as a difference or percent change (rather than absolute values); and (iv) accurately report any notable deviations from this guidelines.

Conclusion

It is anticipated that these guidelines will promote consistent data reporting, which will facilitate inter‐comparison of study results.     

Baseline transepidermal water loss in patients with acute and healed irritant contact dermatitis

To examine the skin harrier function of patients with acute and healed irritant contact dermatitis ( n = 80) baseline transepidermal water loss (TEWL) was quantitatively measured using an evaporimeter. Healthy subjects served as controls ( n = 40). Test areas were the forearm and the thigh. A significant increase in TCVV'L was observed in the patients with acute and with healed irritant contact dermatitis (ICD) as compared LO healthy volunteers ( P ≤ 0.01). TEWL values in both test areas were com parable and markedly correlated ( p ≤ 0.01). with each other in every group. Thus, it is possible that basal TEWL depends more on the intrinsic skin barrier function of the subjects rather than the 2 anatomical regions examined. TEWL at the forearm with acme ICD was significantly higher ( P ≤ 0.01). than that of the group with healed ICD, but not for TCWL at the thigh suggesting that ICD may aggravate the barrier function of the adjacent involved skin. It is assumed, that increased basal TEWL in patients with ICD may relied a constitutional deviation of epidermal barrier function. This event seems to be comparable with the well-known symptom of atopic individuals. Using a detailed atopic scoring system in such a study may clarify the question of whether a proportion of patients with hand ICD may indeed be atopic individuals.     

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.     

Comparative evaporimetry in man

BACKGROUND/AIMS: Transepidermal water loss (TEWL) measurements are frequently used; the most widely utilized instrument has been the open chamber device. Traditional open-chamber systems for measuring TEWL have limitations related to ambient and body-induced airflows near the probe, probe size, measurement site and angles. Recent technology provides a portable and battery-operated closed chamber Evaporimeter. It is presumably less affected by external factors such as room- or body-induced airflows, breathing or heating of the probe by the operators' hand. This study compares this commercial instrument, a closed chamber device, with a traditional open-chamber device. METHODS: Two open chamber devices and one closed chamber device were used in such a way that each instrument could simultaneously measure TEWL in an identical experimental environment with known relative humidity and temperature values. TEWL values of seven locations on healthy volunteers were measured simultaneously with each instrument in the same room according to the guidelines of the standardization group of the European society of contact dermatitis. RESULTS: For TEWL values of all forearm locations, there was no statistically significant difference between the mean values measured by all three instruments. For TEWL values of forehead locations, there was a significant difference between the mean values of open chamber device and closed chamber device. For the forehead, values from closed chamber device were higher than the open one. CONCLUSION: The TEWL values measured by all instruments were constant with small standard deviations. These instruments appear sufficiently robust that a standardization group could document similarities and differences with in vitro models. We suspect that both techniques will continue to be used and that the closed method will find increasing use because of its ease of use.     

The barrier component and the driving force component of transepidermal water loss and their application to skin irritant tests

BACKGROUND/AIM: According to Fick's law of diffusion, the rate of transepidermal water loss (TEWL) is determined by a barrier component and a driving force component. The objective of this study is to propose novel indicators for the assessment of skin irritation potential from chemicals using these components. METHODS: Before and after acetone/ether (AE), sodium lauryl sulfate (SLS) and nicotinic acid methyl ester (NME) treatments, the apparent mass transfer coefficient of water, K, of the stratum corneum (SC) and the apparent water vapor pressure, P(d), at the interface between SC and epidermis were estimated as measures of the SC barrier and the driving force, respectively. RESULTS: After AE treatment, K showed marked increase and P(d) remained approximately constant. All participants reacted to NME with erythema and the laser-Doppler flowmetry (LDF) value peaked at around 30 min. While there was a change in P(d), which parallels with LDF changes, K showed little variation. Repeated SLS treatment induced a slight increase in P(d) besides an increase in K. In the meantime, all participants reacted with subtle erythema. CONCLUSIONS: Our results suggest that not only the SC barrier but also the driving force determines variations in the TEWL rates during skin irritant tests. Together, K and P(d) will provide us with invaluable information about skin condition.     

Incorporation of ceramide 3B in dermatocosmetic emulsions: effect on the transepidermal water loss of sodium lauryl sulphate-damaged skin

BACKGROUND: In previous work we reported on the efficacy of cosmetic body lotions enriched with skin-identical lipids to reduce the transepidermal water loss (TEWL) of ageing and sodium lauryl sulphate (SLS)-damaged skin. The observations made depended on the experimental design and clearly raised the question of the importance of the galenic formulation of skin ceramide-containing products. OBJECTIVES: The aim of the present work was to study the different galenic forms in which ceramide 3B (0.2% w/v) can be incorporated into common o/w emulsions. In addition, we investigated whether supplementation of skin care products with ceramide 3B enriched with penetration enhancers and coemulsifiers could exert a beneficial effect on barrier function, done by measuring their effects on the TEWL of SLS-induced scaly skin. RESULTS: We found that the technique of incorporating ceramide 3B into the o/w emulsions was important for their final stability. However, no additional positive effect on the TEWL values of SLS-damaged skin could be observed when the efficacy of the ceramide-containing emulsions was compared with that of proper controls. CONCLUSIONS: Although suitable galenic formulas were developed, no positive effect on TEWL could be observed when ceramide 3B was added in a final concentration of 0.2% (w/v) to different o/w emulsions and applied to SLS-damaged skin.