Role of basal sweating in maintaining skin hydration in the finger: A long-standing paradox in dry skin resolved

Influence of skin hydration level on the occurrence of blisters on the foot during hiking

Friction blisters are common among outdoor enthusiasts, yet their causes remain uncertain. This study aimed to compare foot hydration in long-distance hikers with and without blisters, and to assess variability based on age and sex. An observational case-control study involving 86 hikers was conducted. Skin hydration was measured using a corneometer on various foot zones. Data on blister count, footwear, sex, age, and temperature were recorded. The most hydrated zones were the digital area, forefoot, and heel. Higher hydration was found in the blister group (61.6%) compared to the control group (38.4%). A significant relationship between hydration and blisters was observed in the left foot (p = 0.032). Total foot hydration was higher in women (p = 0.007) and inversely related to age (r = -0.333; p = 0.002). Hydration values above 30.40 a.u. in the right foot and 27.37 a.u. in the left foot were linked to blisters with 80% sensitivity. This study highlights the variability in foot hydration and its relationship with blisters. The influence of age and wet socks underscores the complexity of blister formation, emphasizing the need for future research on effective prevention.

Sweat Protects against Contact Hypersensitivity: Transient Sweat Suppression Compromises Skin Barrier Function in Mice

Although subtle barrier defects may facilitate allergen penetration, thereby enabling allergic sensitization, the relationship between sweating disturbance and skin barrier function is unknown. However, many studies on contact hypersensitivity in mice examined ear skin, which does not sweat, instead of the footpad, where sweating is uniquely present. In this study, we assessed whether sweat suppression in the footpad before hapten application provoked a skin barrier abnormality and reduced inflammatory thresholds to topical haptens. Mice without any genetic skin barrier dysfunction displayed markedly reduced inflammatory thresholds to haptens under transient sweat suppression before hapten application. Epicutaneously applied haptens penetrated the skin more robustly in the presence of sweat suppression compared with that in its absence, although this increase was abolished by exposure to high-humidity conditions. These mice displayed a subtle atopic dermatitis-like inflammation mediated by type 2 response-dominant inflammation and increased IgE responses, mimicking some events occurring in nonlesional atopic dermatitis skin in humans and in murine models. These lesions were dramatically attenuated by exposure to high-humidity conditions. In our model, hapten sensitization does not require mechanical injury, explaining why sensitization occurs through nonlesional atopic dermatitis skin. Awareness of the importance of preserving sweating responses is essential to prevent occupational contact dermatitis and atopic dermatitis.

Are There Ethnic Differences in Hand Eczema? A Review

Hand eczema is a common disease with economic and social ramifications. This study undertakes a review of certain existing literature to provide insight into contributory factors which may result in the varying prevalence and severity of hand eczema among different ethnic groups, particularly to identify modifiable risk factors, as well as to ascertain knowledge gaps for future research direction. The existing literature suggests that factors including (a) genes, (b) differing skin physiology, (c) cultural practices, (d) dietary habits and associated food preparation, (e) climate, (f) predominant occupations, (g) socioeconomic factors, and (h) dissimilar laws and regulations may account for the disparity in the risk of hand eczema among different ethnicities. Given that endogenous factors cannot be avoided, but certain exogenous aspects can be modified, especially as the environment plays an important role in hand eczema flares, it is helpful from a practical perspective to focus on addressing the modifiable risk factors. These factors pertain to unique cultural practices, customs, and food preparation methods. Healthcare professionals should be well-acquainted with such factors to tailor the treatment approach for patients of different ethnicities accordingly because, with globalization, physicians face increasingly diverse patient populations such that cultural customs no longer remain limited to particular geographic regions.