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.     

The relationship of transepidermal water loss to skin temperature in psoriasis and eczema.

Transepidermal water losses (TEWL) from psoriatic and eczematous skin were measured while skin temperature was varied between 29 degrees C and 37 degrees C. The relationship of TEWL to skin temperature in these diseases is different from that obtaining in normal skin. These differences are thought to be due to the altered filtration properties of diseased stratum corneum. Formulae were devised to allow TEWL rates in psoriasis and eczema to be expressed at a standard temperature for comparative purposes.     

Effect of repeated ultraviolet irradiation on skin of hairless mice

Summary The effect of repeated UV-irradiation on mechanical and biochemical parameters was studied in skin of hairless mice. UV-A irradiation for a period of 1 h daily over 8 weeks caused only a slight increase in skin thickness and a decrease in ultimate strain. The changes induced by UV-B and C, however, were quite remarkable.Skin thickness was increased depending on the daily dose exposure time (15–90 s at an irradiation rate of 20 mW/cm² UV-B and A and of 14 mW/cm² UV-C) and the duration of treatment (1–6 weeks). Ultimated load, tensile strength and modulus of elasticity showed an increase following medium dosages after 1 and 2 weeks, however, a decrease after high dosages and longterm treatment. Ultimate strain was found to be the most sensitive parameter being decreased depending on exposure time and duration of treatment. Insoluble collagen and total collagen were decreased after long-term treatment thus being correlated with the mechanical parameters. The elastin content was only barely influenced and not correlated with the mechanical data, e.g. the modulus of elasticity. Thus, a favourable effect of short-term treatment with low doses of UV-irradiation of mechanical parameters of skin could be demonstrated. Long-term treatment with relatively high doses of UV-B, however, resulted in unfavourable effects, whereby first ultimate strain, then ultimate load, modulus of elasticity and tensile strength were decreased.     

Murine auricular transepidermal water loss -- a novel approach for evaluating irritant skin reaction in mice

The standard method for evaluating contact allergy in mice is the ear swelling technique. However, in experimental irritant contact dermatitis, the epidermal barrier disruption, that represents a predominant effect of irritants, cannot be assayed by this METHOD: An appropriate method to evaluate barrier disruption is the measurement of transepidermal water loss (TEWL) but to date this has so far been possible only on the trunk of hairless or shaved mice. We therefore developed a new technique to measure the TEWL of mice ears (murine auricular TEWL: MATEWL). After patch testing with irritants and allergens, respectively, we found that the ear swelling method is most suitable for evaluating allergic skin reactions, whereas MATEWL is most appropriate for evaluating irritant skin reactions.     

Connective tissue alterations in the skin of ultraviolet irradiated hairless mice

Connective tissue alterations were induced in hairless mouse skin by ultraviolet (UV) irradiation. Hairless mice were irradiated three times a week for 10 weeks with sunlamps (UVA and UVB) and the skin was examined using immunochemical and biochemical techniques. Indirect immunofluorescence was performed with antibodies directed against elastin, microfibrillar proteins, and fibronectin. Increased fluorescence was observed in the actinically damaged skin for elastin, microfibrillar proteins, and fibronectin. The elastic fiber components, elastin and microfibrillar proteins, were then isolated and quantified. Control skin contained approximately 0.1% by dry weight of elastic fiber components, whereas actinically damaged skin contained 0.2% by dry weight. These data are consistent with previous observations of elastic fiber hyperplasia in UV irradiated mice. In addition, irradiated mouse skin contained 1.12 mg of extracted fibronectin per gram wet weight as compared with 0.59 mg in control skin. Irradiated mouse skin contained increased quantities of hyaluronic acid and chondroitin sulfate (uronic acid content). These studies further support the validity of the UV irradiated hairless mouse as a model of human dermal photoaging.     

Effects of single-dose ultraviolet radiation on skin superoxide dismutase, catalase, and xanthine oxidase in hairless mice

The effects of a single exposure to UVB radiation on skin antioxidant enzymes and superoxide-generating xanthine oxidase were examined in Skh:HR-1 hairless mice. Significant decreases in superoxide dismutase (SOD) and catalase (CAT) were observed by 12 h after UV irradiation and remained depressed for up to 72 h. No induction of xanthine dehydrogenase (XD) or xanthine oxidase (XO) occurred with UV treatment, although significant hyperplasia was evident. Ornithine decarboxylase was induced after UV irradiation as has been previously reported. These results demonstrate significant biochemical effects of a single dose of UVB on murine epidermis, especially in terms of antioxidant defenses.     

Assessment of skin barrier function in podoconiosis: measurement of stratum corneum hydration and transepidermal water loss

Background Podoconiosis is a common cause of lymphoedema in barefoot workers in Ethiopia and other countries. It has severe consequences for patients’ physical function, quality of life and economic status. Aims To investigate stratum corneum (SC) hydration and transepidermal water loss (TEWL) in patients with podoconiosis compared with controls. Methods In total, 55 patients and 20 controls were recruited. For each study subject, SC and TEWL measurements were taken, along with foot and lower leg circumferences. Measurements were compared between the patient and control groups. Results Foot circumferences tended to be higher in patients with podoconiosis, with the mean foot:leg circumference ratio being 1·19 (95% confidence interval 1·11–1·28) times that for controls (P = 0·001). There was no detectable difference between patients and controls in TEWL values (P > 0·05); however, SC hydration was significantly lower in patients vs. controls for the foot (P = 0·004) and lower leg (P = 0·046) sites. Conclusions Patients with podoconiosis have significantly lower SC hydration in the skin of their lower legs and feet than controls, which may lead to cracking and splitting, and increased risk of lymphoedema and infection.     

Human labia majora skin: transepidermal water loss in vivo.

Transepidermal water (TEW) loss of normal vulvar and flexor forearm skin was measured in 12 subjects. A significantly elevated vulvar TEW loss was demonstrated. Depsite subcutaneous administration of atropine in seven subjects to eliminate eccrine sweating, no alteration in the elevated TEW loss was found. A significant anatomic and/or physiologic uniqueness of vulvar skin is demonstrated and warrants further investigation.     

Stratum corneum lipid morphology and transepidermal water loss in normal skin and surfactant-induced scaly skin

Stratum corneum lipid morphology was evaluated using attenuated total reflectance infrared spectroscopy (ATR-IR) in normal skin and surfactant-induced scaly skin to evaluate skin barrier function. To evaluate the degree of order of the intercellular lipid alkyl chain conformation, we measured the wavenumbers (frequency shifts) of the symmetrical and asymmetrical C-H stretching vibrations observed at approximately 2850 cm^–1 and 2920 cm^–1, respectively. There was a correlation between the wave-number and transepidermal water loss in normal skin. However, no difference was observed in surfactant-induced scaly skin from the baseline value in the wavenumbers of the C-H vibrations. These results suggest that in normal skin, lipid morphology plays an important role in the barrier function of the stratum corneum. However, the decline in barrier function in scaly skin is not due to conformational disorder of the lipid alkyl chain.     

Effect of ultraviolet (UV) radiation and UVB-absorbing sunscreen ingredients on 7,12-dimethylbenz(a)anthracene-initiated skin tumorigenesis in hairless mice

These experiments describe the enhancement of 7,12-dimethylbenz(a)anthracene (DMBA)-initiated skin tumorigenesis in hairless mice by subsequent chronic ultraviolet (UV) irradiation of the same skin site. Each carcinogen was administered at a level that separately resulted in threshold tumorigenesis. The cocarcinogenic response was evident as a marked increase in tumour incidence, tumour multiplicity and degree of tumour malignancy. Irradiation through the topically applied UVB (290-315 nm)-absorbing sunscreen ingredient, 2-ethylhexyl-p-methoxycinnamate, totally protected from the photoenhancement. However, irradiation through an alternative UVB absorber, octyl-N-dimethyl-p-aminobenzoate, failed to protect from photoenhancement. A possible immunologic role for the enhancement of DMBA tumorigenesis by UV radiation is proposed.     

Dietary glucosylceramide improves skin barrier function in hairless mice

BACKGROUND: Sphingolipids are known to play an important role in both water retention and epidermal permeability barrier function in mammalian stratum corneum. However, little is known about the effects on epidermal function of orally administered sphingolipids. OBJECTIVE: We examined the effect of dietary glucosylceramide (GluCer) on the maintenance and recovery of epidermal barrier function. METHODS: Hairless mice were fed a particular diet (HR-AD) for 4 weeks to induce chronic skin perturbation. Subsequently, a normal diet supplemented with GluCer (from rice bran and germ) was provided for the next 4 weeks. Transepidermal water loss (TEWL) and stratum corneum flexibility were measured throughout this recovery phase. Additional hairless mice were fed a diet with or without a maize-extracted GluCer supplement for 5 weeks, then their skin was acutely perturbed with repeated tape-stripping, and the TEWL was measured. RESULTS: Although skin functions were generally lower following chronic perturbation, in GluCer-fed mice the TEWL was significantly reduced at 2 weeks and the stratum corneum flexibility was increased at 3 weeks compared to controls. Following acute barrier perturbation by tape-stripping, mice an HR-AD fed a GluCer diet exhibited enhanced recovery compared with the control diet group. CONCLUSION: These results demonstrate that in hairless mice skin barrier functions impaired by chronic or acute perturbations were improved by dietary GluCer. The oral administration of GluCer may be useful for the preservation and recovery of epidermal barrier functions an HR-AD.     

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.