A study of skin characteristics according to humidity during sleep

Fluctuations in equine cutaneous pH and transepidermal water loss with time of day and ambient conditions

Cutaneous pH and transepidermal water loss (TEWL) are commonly utilized measures in dermatological research as they provide information concerning barrier function. The importance of dermal health has become more evident in recent years. Accordingly, the aim of this work was to identify natural fluctuations in the biophysical parameters of healthy equine skin. Cutaneous pH and TEWL was collected on nine mares at 6:00 AM, 12:00 PM, and 6:00 PM daily for five days on the nose, withers, girth area, mid-back, and base of tail. Ambient temperature and humidity were measured at each collection. Statistical analysis was completed using SAS On Demand. Tests included repeated measures, ANOVA, and regression analysis. Mean cutaneous pH significantly differed by day (P = 0.0052) and time (P = 0.0073) but was unaffected by anatomical location (P = 0.2841). Interestingly, cutaneous pH had a significant interaction of day and location (P = 0.0004). Mean TEWL measures significantly differed by day (P < 0.0001), time (P < 0.0001), and anatomical location (P = 0.0231). Interaction of day and time had a significant effect on TEWL (P < 0.0001) and also resulted in a three-way interaction of day, time, and location (P = 0.0167). There were no significant associations of pH with temperature and humidity. All measures of TEWL across all locations were significantly correlated with temperature and humidity (P < 0.0001). Cutaneous pH and TEWL measures are affected by environmental conditions which should be considered in future models and work using dermal characteristics of horses.

A modified protocol for studying filaggrin degradation using a reconstructed human epidermis model under low and high humidity

BACKGROUND

Filaggrin (FLG) is an essential protein that plays a vital role in maintaining skin barrier function and moisture levels, allowing the skin to adapt to dry environments. However, the precise temporal dynamics of FLG metabolism in the human epidermis remain poorly understood, and suitable tools to study these time-dependent effects are currently lacking.

OBJECTIVE

To investigate the molecular mechanisms and time course of FLG metabolism and skin barrier function under high- and low-humidity conditions, utilizing a reconstructed epidermis model.

METHODS

EpiSkin specimens cultured under humid or dry conditions for varying durations (2-48 h) were compared by assessing FLG degradation and skin barrier formation using immunofluorescence staining and western blotting.

RESULTS

Under conditions of low humidity, the proteolysis of FLG in EpiSkin increased between 4 and 12 h and was accompanied by elevated levels of cysteine-aspartic protease (caspase)-14. The expression of peptidyl arginine deiminase 1 and calpain 1 also increased at 4 h. However, after 24 h, the expression of these three FLG-degrading proteins significantly decreased. Conversely, the levels of pyrrolidone-5-carboxylic acid and urocanic acid initially decreased at 2 h and then increased between 12 and 24 h. Additionally, the expression of skin barrier proteins, such as FLG, transglutaminase 5, loricrin and zonula occludens-1, decreased starting from 12 h. Notably, epidermal cell viability and activity were also inhibited.

CONCLUSION

We propose a reliable and ethical model to study the temporal dynamics of FLG metabolism and its role in skin barrier function. Using a commercially reconstructed epidermis to mimic dry skin formation obviates the need for animal and human testing.

Evaluation of changes for sebum, skin pore, texture, and redness before and after sleep in oily and nonoily skin

BACKGROUND

People whose skin type is oily have experienced an esthetic and hygienic discomfort due to the excessive secretion of the sebum during the day and night time, and therefore sebum control is required. In this study, we aimed to find out whether the skin status between the oily and nonoily skin indicates a significant difference before and after sleep.

MATERIALS AND METHODS

Forty Korean males and females whose skin type was oily or nonoily participated in this study. To investigate the difference of the skin between oily and nonoily skin before and after sleep, we measured the sebum, skin pore, texture, and redness on their cheek at baseline and after 4-h sleep. Moreover, the significant level was determined at p < 0.05.

RESULTS

Parameters of sebum and skin pore significantly increased after 4-h sleep compared with baseline in the oily and nonoily skin (p < 0.05). Moreover, the increment of sebum and pore parameters in the oily skin was significantly higher than those in the nonoily skin (p < 0.05). In the case of skin texture and redness, parameters of them were significantly changed after 4-h sleep compared with baseline only in the oily skin (p < 0.05), and there was no significant difference among groups.

CONCLUSIONS

We found that the change rates of the sebum secretion and skin pore in oily skin were significantly higher than those in nonoily skin after 4-h sleep. These results suggest the necessity of the skin care depending on the skin type before sleeping.

Transepidermal water loss (TEWL): Environment and pollution-A systematic review

Introduction

Transepidermal water loss (TEWL) is an objective measurement of skin integrity measured as the amount of water lost across the stratum corneum. TEWL varies greatly across variables such as age and anatomic location, and disruptions in the skin barrier have been linked to inflammatory dermatoses such as psoriasis and atopic dermatitis. Impact of environmental conditions and pollution on TEWL has yet to be determined. Accordingly, this review summarizes effects of environmental conditions and pollution on TEWL.

Methods

A comprehensive literature search was performed using Embase, PubMed, and Web of Science to find human studies that provided data on environmental conditions and/or pollution and TEWL.

Results

In total, 15 studies were included, with 11 studies examining environmental and seasonal conditions on TEWL and four examining pollution. All studies examining pollution showed increased TEWL in people exposed to particulate matter or NO2. Contradictory results were found on the effects of season and climate across the 11 studies, with no consensus reached.

Conclusion

Exposure to pollution is reported to cause increases in TEWL, likely through free radical damage. Significant discrepancies exist among current literature as to the effects of season and climate on TEWL. There is a need to continue examining environmental variables other than temperature and relative humidity, such as atmospheric and steam pressure, that may impact TEWL.

Impact of Exposome Factors on Epidermal Barrier Function in Patients with Obstructive Sleep Apnea Syndrome

Exposome factors, such as sleep deprivation and diet, could affect skin barrier function. The objectives of this study are to compare skin barrier function between patients with Obstructive Sleep Apnea Syndrome (OSAS) and healthy individuals, and to evaluate the effect of other exposome factors on skin. A cross-sectional study was conducted. Patients with OSAS and healthy volunteers matched by age and sex were included. OSAS severity was assessed by the Apnea-Hypopnea Index (AHI). Validated questionnaires were used to assess diet, anxiety, depression, and psychological stress. Skin barrier function parameters including temperature, erythema, melanin, pH, transepidermal water loss (TEWL), and stratum corneum hydration (SCH) were measured on the volar forearm. A total of 86 participants were included, 56 patients with OSAS and 30 healthy volunteers. TEWL was higher in OSAS patients than in healthy individuals (8.01 vs. 8.68 g·m⁻²·h⁻¹). Regarding disease severity, severe patients had higher TEWL values (9.31 vs. 8.46 vs. 7.08 g·m⁻²·h⁻¹) compared to moderate and mild patients. Patients with OSAS had significantly lower sleep quality (11.89 vs. 6.47 Pittsburgh Sleep Quality Index score; p < 0.001), poor adherence to the Mediterranean Diet (8.46 vs. 9.77; p = 0.005), and significantly higher anxiety and depression levels than healthy individuals. In conclusion, patients with OSAS may have skin barrier impairment, reflected in higher TEWL values. These patients also have higher levels of anxiety, depression, stress, and a lower adherence to a Mediterranean Diet, all exposome factors that might impact on skin barrier function.

Seasonal variations in the skin parameters of Caucasian women from Central Europe

BACKGROUND

The human skin is greatly affected by external factors such as UV radiation (UVR), ambient temperature (T), and air humidity. These factors oscillate during the year giving rise to the seasonal variations in the skin properties. The aim of this study was to evaluate the effect of seasons, environmental T, relative and absolute humidity on the skin parameters of Caucasian women, perform a literature review and discuss the possible factors lying behind the found changes.

MATERIALS AND METHODS

We measured stratum corneum (SC) hydration, transepidermal water loss (TEWL), sebum level, erythema index, and elasticity parameters R2 and R7 on the forehead and the cheek of Caucasian women from the Czech Republic throughout the year. We also performed a non-systematic literature review focused on the seasonal variations in these skin parameters.

RESULTS

We confirmed a well-documented low SC hydration and sebum production in winter. In spring, we found the lowest TEWL (on the forehead) and the highest SC hydration but also the highest erythema index and the lowest elasticity presumably indicating skin photodamage. For most of the skin parameters, the seasonal variations probably arise due to a complex action of different factors as we extensively discussed.

CONCLUSION

The data about the seasonal variations in the skin parameters are still highly inconsistent and further studies are needed for better understanding of the normal skin changes throughout the year.

Short-term skin reactions following use of N95 respirators and medical masks

Background

In the context of the COVID‐19 pandemic, cases of adverse skin reactions related to the wearing of masks have been observed.

Objectives

To analyze the short‐term effects of N95 respirators and medical masks, respectively, on skin physiological properties and to report adverse skin reactions caused by the protective equipment.

Methods

This study used a randomized crossover design with repeated measurements. Twenty healthy Chinese volunteers were recruited. Skin parameters were measured on areas covered by the respective masks and on uncovered skin 2 and 4 hours after donning, and 0.5 and 1 hour after removing the masks, including skin hydration, transepidermal water loss (TEWL), erythema, pH, and sebum secretion. Adverse reactions were clinically assessed, and perceived discomfort and non‐compliance measured.

Results

Skin hydration, TEWL, and pH increased significantly with wearing the protective equipment. Erythema values increased from baseline. Sebum secretion increased both on the covered and uncovered skin with equipment‐wearing. There was no significant difference in physiological values between the two types of equipment. More adverse reactions were reported following a N95 mask use than the use of a medical mask, with a higher score of discomfort and non‐compliance.

Conclusions

This study demonstrates that skin biophysical characters change as a result of wearing a mask or respirator. N95 respirators were associated with more skin reactions than medical masks.