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

Longitudinal study of the interplay between the skin barrier and facial microbiome over 1 year

Skin is a diverse ecosystem that provides a habitat for microorganisms. The skin condition and the skin microbiome interact each other under diverse environmental conditions. This study was conducted on 10 study participants for a one-year, from September 2020 to August 2021, to investigate the variability of skin microbiome and skin biophysical parameters [TEWL, hydration, and elasticity (R5)] according to season, and to understand the interplay between skin microbiome and skin characteristics. We identified that Cutibacterium, Corynebacterium, Staphyloccocus, unclassified genus within Neisseriaceae, and Streptococcus were major skin microbial taxa at the genus level, and fluctuated with the seasons. Cutibacterium was more abundant in winter, while Corynebacterium, Staphylococcus, and Streptococcus were more abundant in summer. Notably, Cutibacterium and skin barrier parameter, TEWL, exhibited a co-decreasing pattern from winter to summer and showed a significant association between Cutibacterium and TEWL. Furthermore, functional profiling using KEGG provided clues on the impact of Cutibacterium on the host skin barrier. This study enhances our understanding of the skin microbiome and its interplay with skin characteristics and highlights the importance of seasonal dynamics in shaping skin microbial composition.

Measurement of human skin moisture via high-frequency spectroscopy

High-frequency spectroscopy (HFS) is an analytical method that is sensitive to slight changes in the dielectric properties of materials. Since water has high permittivity, HFS can be used to detect changes in water content in materials. In this study, we employed HFS to measure human skin moisture during a water sorption-desorption test. Skin without any treatment showed a resonance peak at approximately 1150 MHz. Furthermore, the peak shifted to lower frequency immediately after the application of water to the skin and gradually returned to its original frequency as time progressed. The resonance frequency obtained via least-squares fitting showed that the applied water remained in the skin after 240 s from the beginning of the measurement. These results illustrated that HFS measurements can monitor the progression of decreasing moisture content in human skin during a water sorption-desorption test.

Effects of one year of daily face mask wearing on the skin during the coronavirus disease 2019 pandemic

Background

As coronavirus disease 2019 (COVID‐19) continues, the long‐term daily use of masks is increasing. A full year includes the four seasons of spring, summer, autumn, and winter. Skin may have been affected by the seasons and further affected by the use of masks. In a previous study, we confirmed the short‐term and 6‐month effects of wearing face masks. In this study, we investigated how certain characteristics of the skin change when wearing a mask for 1 year. Furthermore, we compared skin covered by the mask (mask‐skin zone) to skin that was not covered.

Materials and methods

The participants were 18 healthy adults (8 men; 10 women) who were asked to wear masks in their daily lives from June 2020 to June 2021. During this period, participants’ skin characteristics, such as trans‐epidermal water loss, skin hydration, skin elasticity, skin keratin amount, skin pore area, skin temperature, skin redness, and skin color, were measured five times.

Results

Trans‐epidermal water loss, skin keratin amount, skin pore area, skin color, and skin elasticity changed significantly during the year. Furthermore, trans‐epidermal water loss, skin hydration, skin keratin amount, skin pore area, and skin color were significantly different between the mask‐wearing and non‐mask‐wearing areas of the face.

Conclusion

The skin characteristics of the mask‐skin zone can be affected by long‐term wearing of a face mask under lifestyle and environmental conditions. During the COVID‐19 pandemic, skin care for the mask‐skin zone is also necessary for people who do not wear masks on a daily basis.

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.

Newborn-oriented and environmental factors for newborns' skin barrier functions

AIM

This study aimed to examine newborn-oriented and environmental factors of newborn skin barrier functions.

METHODS

This was a retrospective secondary analysis of 227 newborns from a previous study. Newborn skin barrier functions were measured on the fourth day after birth via the following parameters: stratum corneum hydration, transepidermal water loss, skin pH, and sebum secretion. Skin barrier functions were measured at four body sites; their averaged values were used for the analysis. The associations among skin barrier functions, newborn-oriented factors, and environmental factors were evaluated. Multiple regression analysis was performed using a forced entry method, and independent variables for which p-values were <.05 in Student's t test, analysis of variance, and Pearson's correlation analysis were included.

RESULTS

A total of 211 participants were analyzed. The mean ± standard deviation values of stratum corneum hydration, transepidermal water loss, skin pH, and sebum secretion were 28.58 ± 8.40 and 7.28 ± 2.02 g/m² /h, 5.77 ± 0.53, and 23.59 ± 15.89 μg/cm² , respectively. Newborn-oriented factors (gestational days, weight, amount of vernix, and parity) and environmental factors (birth season) were significantly associated with one or more skin barrier functions.

CONCLUSIONS

Newborn-oriented (including labor- and delivery-related) and environmental factors were associated with the skin barrier functions. The newborn maturity level, newborn sex, environmental temperature, and humidity may affect skin barrier functions in newborns. Further studies should focus on the effects of these factors on newborn skin barrier assessments, and develop tailored skincare strategies based on their characteristics.

Population informative markers selected using Wright's fixation index and machine learning improves human identification using the skin microbiome

Microbial DNA, shed from human skin, can be distinctive to its host and thus help individualize donors of forensic biological evidence. Previous studies have utilized single locus microbial DNA markers (e.g., 16S rRNA) to assess the presence/absence of personal microbiota to profile human hosts. However, since the taxonomic composition of the microbiome is in constant fluctuation, this approach may not be sufficiently robust for human identification (HID). Multi-marker approaches may be more powerful. Additionally, genetic differentiation, rather than taxonomic distinction, may be more individualizing. To this end, the non-dominant hands of 51 individuals were sampled in triplicate (n = 153). They were analyzed for markers in the hidSkinPlex, a multiplex panel comprising candidate markers for skin microbiome profiling. Single nucleotide polymorphisms (SNPs) with the highest Wright's fixation index (F_ST) estimates were then selected for predicting donor identity using a support vector machine (SVM) learning model. F_ST is an estimate of the genetic differences within and between populations. Three different SNP selection criteria were employed: SNPs with the highest-ranking F_ST estimates 1) common between any two samples regardless of markers present (termed overall); 2) each marker common between samples (termed per marker); and 3) common to all samples used to train the SVM algorithm for HID (termed selected). The SNPs chosen based on criteria for overall, per marker, and selected methods resulted in an accuracy of 92.00%, 94.77%, and 88.00%, respectively. The results support that estimates of F_ST, combined with SVM, can notably improve forensic HID via skin microbiome profiling. IMPORTANCE There is a need for additional genetic information to help identify the source of biological evidence found at a crime scene. The human skin microbiome is a potentially abundant source of DNA that can enable the identification of a donor of biological evidence. With microbial profiling for human identification, there will be an additional source of DNA to identify individuals as well as to exclude individuals wrongly associated with biological evidence, thereby improving the utility of forensic DNA profiling to support criminal investigations.