The impact of air pollution on the facial skin of Caucasian women using real-life pollutant exposure measurements.

BACKGROUND: To date, studies examining the effect of air pollution on skin characteristics have relied on regional pollution estimates obtained from fixed monitoring sites. Hence, there remains a need to characterize the impact of air pollution in vivo in real-time conditions. We conducted an initial investigation under real-life conditions, with the purpose of characterizing the in vivo impact of various pollutants on the facial skin condition of women living in Paris over a 6-month period. MATERIALS AND METHODS: A smartphone application linked to the Breezometer platform was used to collect participants' individual exposures to pollutants through the recovery of global positioning system (GPS) data over a 6-month period. Daily exposure to fine particulate matter (PM 2.5 µm and PM 10 µm), pollen, and air quality was measured. Facial skin color, roughness, pore, hydration, elasticity, and wrinkle measurements were taken at the end of the 6-month period. Participants' cumulated pollutant exposure over 6 months was calculated. Data were stratified into two groups (lower vs. higher pollutant exposure) for each pollutant. RESULTS: 156 women (20-60 years-old) were recruited, with 124 women completing the study. Higher PM 2.5 µm exposure was associated with altered skin color and increased roughness under the eye. Higher PM 10 µm exposure with increased wrinkles and roughness under the eye, increased pore appearance, and decreased skin hydration. Exposure to poorer air quality was linked with increased forehead wrinkles and decreased skin elasticity, while higher pollen exposure increased skin roughness and crow's feet. CONCLUSION: This study suggests a potential correlation between air pollution and facial skin in real-life conditions. Prolonged exposure to PM, gases, and pollen may be linked to clinical signs of skin ageing. This study highlights the importance of longer monitoring over time in real conditions to characterize the effect of pollution on the skin.

Modeling of global skin aging indices among Caucasian and Asian women.

BACKGROUND: The skin aging process is defined as the gradual degradation of several skin properties such as firmness, color, or the appearance of wrinkles. These properties can be assessed by trained experts, who perform an overall evaluation of the entire face. OBJECTIVE: The objective of this paper is the construction of two Global Skin Aging Indices specifically designed to model the overall skin aging process of Caucasian and Asian women. METHODS: Two hundred forty Asian women and 129 Caucasian women aged between 20 and 60 years old are recruited. Parameters related to wrinkles, sagging, elasticity, and skin tone are measured (clinically or instrumentally). The global skin aging index is defined as the normalized projection on the first principal component of a principal component analysis of the skin measurements. Then, linear regressions are performed between the indices and age of both panels. RESULTS: The first principal component carries around 50% of the initial variance for both indices. Both Global Skin Aging Indices statistically correlate with age (R2 ≥ 0.7, p-value < 0.05). An equation linking the indices with age is computed. CONCLUSION: The proposed indices are good indicators of the overall aging process for Caucasian and Asian women. They offer new approaches to assess antiaging product efficacy.

Self-perceived and objective measurements of facial puffiness in Chinese women.

BACKGROUND: Facial puffiness, caused by mild or normal fluid retention, commonly experienced by women, may not pose a health risk, but it can be a cause of cosmetic concern. The objectives of this study were to determine whether self-perceived facial puffiness can be measured objectively. MATERIALS AND METHODS: A total of 151 Chinese women between 20 and 68 years of age were recruited. Facial water content, skin thickness, and elasticity were measured at two time points within a day (visit one occurred when the participants perceived they had facial puffiness; visit two occurred when the participants perceived their facial puffiness had subsided). Participants were also given a rating scale to self-evaluate their puffiness and firmness at different regions of the face. RESULTS: The participants could perceive a difference in facial puffiness between the two visits. Water content and skin thickness were significantly higher in all regions of the face for all participants during the first visit. Skin elasticity was also significantly different between visits one and two. There was a significant increase in water content and skin thickness in the lower eyelid region in women who were older than 40 years. CONCLUSION: This is the first study to show that self-perceived facial puffiness can be measured objectively and that skin elasticity can change significantly when facial puffiness subsides.

The effect of air pollution on the skin colour and tone of Chinese women: A multicentre cohort study.

BACKGROUND: Overall facial skin colour is an important sign of perceived health and attractiveness, is predetermined by genetic factors, and is influenced by cultural and living habits, ultraviolet (UV) exposure, climate/seasons and ageing. The objective of this study was to determine the impact of pollution on the skin colour of Chinese women. MATERIALS AND METHODS: A total of 203 Chinese women between 20 and 59 years of age participated in the study and were selected from two cities with different levels of air pollution. Skin colour (L*, a* and b* values), melanin and haemoglobin levels were measured at three sites: the cheek, eye and inner upper arm. Measurements of the inner upper arm were taken as this area of skin was exposed to air pollutants but had minimal exposure to UV light. RESULTS: There were significant differences in skin chromophores between Chinese women living in two different cities with different levels of pollution. The b* value (yellowness) was higher in the eye and cheek region, and the a* value (redness) was lower in the cheek and arm region for women in the moderately polluted city. The melanin index was significantly higher, and the haemoglobin level was lower for the eye region for women living in the city with a higher level of air pollution. CONCLUSION: This study has shown that air pollution may negatively affect the skin colour of Chinese women.

Real-time skin chromophore estimation from hyperspectral images using a neural network.

BACKGROUND: Hyperspectral imaging for in vivo human skin study has shown great potential by providing non-invasive measurement from which information usually invisible to the human eye can be revealed. In particular, maps of skin parameters including oxygen rate, blood volume fraction, and melanin concentration can be estimated from a hyperspectral image by using an optical model and an optimization algorithm. These applications, relying on hyperspectral images acquired with a high-resolution camera especially dedicated to skin measurement, have yielded promising results. However, the data analysis process is relatively expensive in terms of computation cost, with calculation of full-face skin property maps requiring up to 5 hours for 3-megapixels hyperspectral images. Such a computation time prevents punctual previewing and quality assessment of the maps immediately after acquisition. METHODS: To address this issue, we have implemented a neural network that models the optimization-based analysis algorithm. This neural network has been trained on a set of hyperspectral images, acquired from 204 patients and their corresponding skin parameter maps, which were calculated by optimization. RESULTS: The neural network is able to generate skin parameter maps that are visually very faithful to the reference maps much more quickly than the optimization-based algorithm, with computation times as short as 2 seconds for a 3-megapixel image representing a full face and 0.5 seconds for a 1-megapixel image representing a smaller area of skin. The average deviation calculated on selected areas shows the network's promising generalization ability, even on wide-field full-face images. CONCLUSION: Currently, the network is adequate for preview purposes, providing relatively accurate results in a few seconds.

Non-senescent keratinocytes organize in plasma membrane submicrometric lipid domains enriched in sphingomyelin and involved in re-epithelialization.

Membrane lipid raft model has long been debated, but recently the concept of lipid submicrometric domains has emerged to characterize larger (micrometric) and more stable lipid membrane domains. Such domains organize signaling platforms involved in normal or pathological conditions. In this study, adhering human keratinocytes were investigated for their ability to organize such specialized lipid domains. Successful fluorescent probing of lipid domains, by either inserting exogenous sphingomyelin (BODIPY-SM) or using detoxified fragments of lysenin and theta toxins fused to mCherry, allowed specific, sensitive and quantitative detection of sphingomyelin and cholesterol and demonstrated for the first time submicrometric organization of lipid domains in living keratinocytes. Potential functionality of such domains was additionally assessed during replicative senescence, notably through gradual disappearance of SM-rich domains in senescent keratinocytes. Indeed, SM-rich domains were found critical to preserve keratinocyte migration before senescence, because sphingomyelin or cholesterol depletion in keratinocytes significantly alters lipid domains and reduce migration ability.

Three-dimensional conditional random field for the dermal-epidermal junction segmentation.

The segmentation of the dermal-epidermal junction (DEJ) in in vivo confocal images represents a challenging task due to uncertainty in visual labeling and complex dependencies between skin layers. We propose a method to segment the DEJ surface, which combines random forest classification with spatial regularization based on a three-dimensional conditional random field (CRF) to improve the classification robustness. The CRF regularization introduces spatial constraints consistent with skin anatomy and its biological behavior. We propose to specify the interaction potentials between pixels according to their depth and their relative position to each other to model skin biological properties. The proposed approach adds regularity to the classification by prohibiting inconsistent transitions between skin layers. As a result, it improves the sensitivity and specificity of the classification results.

Repeated short climatic change affects the epidermal differentiation program and leads to matrix remodeling in a human organotypic skin model.

Human skin is subject to frequent changes in ambient temperature and humidity and needs to cope with these environmental modifications. To decipher the molecular response of human skin to repeated climatic change, a versatile model of skin equivalent subject to "hot-wet" (40°C, 80% relative humidity [RH]) or "cold-dry" (10°C, 40% RH) climatic stress repeated daily was used. To obtain an exhaustive view of the molecular mechanisms elicited by climatic change, large-scale gene expression DNA microarray analysis was performed and modulated function was determined by bioinformatic annotation. This analysis revealed several functions, including epidermal differentiation and extracellular matrix, impacted by repeated variations in climatic conditions. Some of these molecular changes were confirmed by histological examination and protein expression. Both treatments (hot-wet and cold-dry) reduced the expression of genes encoding collagens, laminin, and proteoglycans, suggesting a profound remodeling of the extracellular matrix. Strong induction of the entire family of late cornified envelope genes after cold-dry exposure, confirmed at protein level, was also observed. These changes correlated with an increase in epidermal differentiation markers such as corneodesmosin and a thickening of the stratum corneum, indicating possible implementation of defense mechanisms against dehydration. This study for the first time reveals the complex pattern of molecular response allowing adaption of human skin to repeated change in its climatic environment.