Fernanda Distante

Alpha hydroxyacids modulate stratum corneum barrier function

Alpha hydroxyacids (AHAs) are used to enhance stratum corneum desquamation and improve skin appearance. The purpose of this study was to evaluate whether some AHAs improve skin barrier function and prevent skin irritation. Eleven healthy subjects (aged 28 ± 6 years. mean ± SD) entered the study. Six test sites of 8×5 cm (four different AHAs, vehicle only (VE) and untreated control (UNT)) were selected and randomly rotated on the volar arm and forearm. The four different AHAs at 8% concentration in base cream were glycolic acid (GA), lactic acid, tartaric acid (TA) and gluconolactone (GLU). The products were applied twice a day for 4 weeks (2 mg/cm2). At week 4, a 5% sodium lauryl sulphate (SLS) challenge patch test was performed under occlusion for 6 h (HillTop chamber. 18 mm wide) on each site. Barrier function and skin irritation were evaluated by means of evaporimetry (Servomed EP‐1) and chromametry (a* value, Minolta CR200) weekly, and at 0.24 and 48 h after SLS patch removal. No significant differences in transepidermal water loss (TEWL) and erythema were observed between the four AHAs at week 4. After SLS challenge. GLU and TA‐treated sites resulted in significantly lower TEWL compared with VE, UNT (P<0.01) and GA (P<0.05) both at 24 and 48 h. Similarly, a* values were significantly reduced after irritation in GLU‐and TA‐treated sites. This study shows that AHAs can modulate stratum corneum barrier function and prevent skin irritation: the effect is not equal for all AHAs. being more marked for the molecules characterized by antioxidant properties.

The modulation of skin irritation

Irritant contact dermatitis (ICD) is a multifactorial disease, the onset and modulation of which depend on both endogenous and exogenous factors. Among the former, age, race, site, sex and history of dermatitis may all be important. Such variables can now readily be quantified by objective noninvasive techniques, such as measurement of transepidermal water loss (TEWL). Moreover, effects of irritants on the epidermis are related to the particular chemical properties of each molecule, contributing further to clinical heterogeneity. Release of cytokines and mediators may be initiated by a number of cells, including living keratinocytes and those of the stratum corneum, thus modulating inflammation and repair. Furthermore, differences in mechanisms of inflammation between acute and chronic ICD may exist, the former being characterized predominantly by inflammation, the latter by hyperproliferation and transient hyperkeratosis. These findings may explain the complexity and difficulty of investigating ICD. Better understanding and quantification of these mechanisms may lead to identification of high‐risk individuals and more effective prevention and treatment.

Effects of water temperature on surfactant-induced skin irritation.

Surfactant‐induced irritant reactions may be elicited by several endogenous and exogenous factors. Among these, surfactant concentration, and duration and frequency of exposure play important rotes. The study focuses on the influence of water temperature in determining damage of the skin barrier. 10 subjects of both sexes entered the study. 4 areas (4×4 cm2) were randomly selected on the volar forearm and were treated with a daily open application of 5% sodium lauryl sulphate for 4 days. The solutions were at 3 temperatures: 4®, 20® and 40 ®C. One site served as untreated control. On the 5th day, skin irritation was evaluated using transepidermal water loss (TEWL) measurements, erythema (a* value), skin reflectance (L* value), hydration (capacitance) and desquamation (stripping). The results show a significant effect of the solutions temperature in determining skin irritation (P < 0.001), Skin damage was higher in sites treated with warmer temperatures and a highly significant correlation (P < 0.001) between irritation and temperature was found. In conclusion, the study shows that water temperature during washing has an important effect on the onset of irritant contact dermatitis.

Oral fish cartilage polysaccharides in the treatment of photoageing: biophysical findings.

The topically applied cosmetic products can be helpful in improving the aged skin condition. The present study shows how oral fish‐cartilage food supplementation can be helpful in improving the treatment of ageing skin. A total of 30 healthy women with signs of skin ageing were studied. Fifteen of the women were treated with a food supplement based on polysaccharides derived from the fish cartilage and a natural mix of antioxidants for 2 months and the other 15 with a placebo. Clinical evaluation and biophysical parameters related to skin function and wrinkle severity, such as silicone replica, skin thickness, mechanical properties, skin colour and capacitance, were measured. The results showed statistically significant changes in the active‐treated group in comparison to the placebo. In particular, dermal thickness (treatment: from 1.13 to 1.23 mm; P < 0.001), skin wrinkling (treatment: from 9.5 to 3.5 Ra; P< 0.002), skin colour (treatment: brighter and less pigmented; P < 0.02) and viscoelasticity (treatment: from 0.70 to 0.97%; P < 0.02) showed considerable improvement. Most of these parameters are related to changes occurring within the dermal matrix, which is improved after the treatment, whereas most of the topically applied cosmetic products have a short‐term effect on superficial structures. A combination treatment (oral and topical) can be more effective in reducing the signs of skin‐ageing.

Effects of site and menstrual cycle on barrier function and stratum corneum water-holding capacity.

Background/aims: Areas of the skin with similar anatomical structure may have different functional behaviour. In vivo barrier function and stratum corneum water‐holding capacity during the menstrual cycle on two sites of the volar forearm (upper and lower) and on the anterior aspect of the thigh were evaluated using the plastic occlusion stress test (POST).