A severe chronic outdoor urban pollution alters some facial aging signs in Chinese women. A tale of two cities

Chronic Exposure to Petroleum-Derived Hydrocarbons Alters Human Skin Microbiome and Metabolome Profiles: A Pilot Study

Petroleum-derived substances, like industrial oils and grease, are ubiquitous in our daily lives. Comprised of petroleum hydrocarbons (PH), these substances can come into contact with our skin, potentially causing molecular disruptions and contributing to the development of chronic disease. In this pilot study, we employed mass spectrometry-based untargeted metabolomics and 16S rRNA gene sequencing analyses to explore these effects. Superficial skin samples were collected from subjects with and without chronic dermal exposure to PH at two anatomical sites: the fingers (referred to as the hand) and arms (serving as an intersubject variability control). Exposed hands exhibited higher bacterial diversity (Shannon and Simpson indices) and an enrichment of oil-degrading bacteria (ODB), including Dietzia, Paracoccus, and Kocuria. Functional prediction suggested enriched pathways associated with PH degradation in exposed hands vs non-exposed hands, while no differences were observed when comparing the arms. Furthermore, carboxylic acids, glycerophospholipids, organooxygen compounds, phenol ethers, among others, were found to be more abundant in exposed hands. We observed positive correlations among multiple ODB and xenobiotics, suggesting a chemical remodeling of the skin favorable for ODB thriving. Overall, our study offers insights into the complex dysregulation of bacterial communities and the chemical milieu induced by chronic dermal exposure to PH.

Facial Skin Aging Characteristics of the Old-Perceived Age in a 20-40 Years Old Chinese Female Population

Purpose

In the quest for a youthful appearance, women use a variety of anti- aging cosmetics. Defining skin problems is especially important for the selection of anti-aging solutions. However, the skin problems faced by Chinese women at different ages are different. This study aimed at Chinese women aged 20-40 years old and analyzed facial skin aging characteristics of those with old-perceived age.

Patients and Methods

The total of 400 standard facial photographs from Chinese female volunteers aged 20-40 was assessed by another 126 Chinese women. The facial areas and skin aging characteristics that influenced age estimation were collected at the same time. Skin aging characteristics, including wrinkles, skin tone, pigmentation and pores, were analyzed based on facial photographs. Groupings were made based on deviation of perceived age from chronological age, and skin aging characteristics among groups were compared.

Results

The perceived age of Chinese women aged 20-40 has a moderate correlation with chronological age. Women aged 20-30 generally had an old-perceived age. Deep skin tone was a prominent problem in this age group, with those who had the older-perceived age observed the darker and redder skin tone. Women aged 31-40 were perceived partly old but appeared with wrinkle aggravation, as well as deepening of redness, enlarged pores, and increased pigmentation at the mid-face. The perceived older women also had more visible frown lines and darker skin tone at the upper face.

Conclusion

The perceived age of Chinese women aged 20-40 tends to deviate from their chronological age. Women aged 20-30 with old-perceived age are associated with deep skin tone, even found darker and redder in older-perceived women group, while women aged 31-40 are associated with wrinkles and deterioration at mid-face area and upper-face problems drive more attention in older-perceived women group.

Awareness of sun exposure risks and photoprotection for preventing pigmentary disorders in Asian populations: Survey results from three Asian countries and expert panel recommendations

BACKGROUND

In this article, we review and discuss the photoprotection behavior of Asians based on the literature, along with a subanalysis of an original online survey, and make recommendations to optimize photoprotection for Asian populations to prevent photoaging and pigmentary disorders.

METHODS

An international panel of eight dermatologists from Asia (China, Korea, Japan, Singapore, Indonesia, and Vietnam) met to discuss sunscreen photoprotection for Asian patients. Additionally, a subanalysis of an online survey by 3000 respondents from three Asian countries (China, Indonesia, and Japan) investigated general public awareness and attitudes to sun exposure.

RESULTS

A pre-meeting survey of the eight experts from Asia showed key concerns of Asian patients consulting dermatologists are pigmentary disorders, especially actinic/senile lentigo, post-inflammatory hyperpigmentation, melasma, vitiligo, and Hori's nevus. The survey subanalysis of participants from China, Indonesia, and Japan with predominantly Fitzpatrick skin types (FST) II to IV revealed that they are particularly concerned about sun exposure causing photoaging and pigmentary disorders. Most of the respondents indicated they have limited knowledge on sunlight radiation and appropriate sunscreen protection factors. Only 22%, 13%, and 3% for China, Indonesia, and Japan, respectively, systematically use multiple protective measures (using sunscreen, avoiding midday sun, staying in the shade, wearing a hat, protective clothing, and sunglasses) when exposed to the sun.

CONCLUSIONS

Further education is needed for Asian populations on the importance of comprehensive daily photoprotection, including broad-spectrum sunscreen, with high UVA and visible light protection, to reduce and prevent photoaging and pigmentary disorders.

Promoting New Approach Methodologies (NAMs) for research on skin color changes in response to environmental stress factors: tobacco and air pollution

Aging is one of the most dynamic biological processes in the human body and is known to carry significant impacts on individuals' self-esteem. Skin pigmentation is a highly heritable trait made possible by complex, strictly controlled cellular and molecular mechanisms. Genetic, environmental and endocrine factors contribute to the modulation of melanin's amount, type and distribution in the skin layers. One of the hallmarks of extrinsic skin aging induced by environmental stress factors is the alteration of the constitutive pigmentation pattern clinically defined as senile lentigines and/or melasma or other pigmentary dyschromias. The complexity of pollutants and tobacco smoke as environmental stress factors warrants a thorough understanding of the mechanisms by which they impact skin pigmentation through repeated and long-term exposure. Pre-clinical and clinical studies demonstrated that pollutants are known to induce reactive oxygen species (ROS) or inflammatory events that lead directly or indirectly to skin hyperpigmentation. Another mechanistic direction is provided by Aryl hydrocarbon Receptors (AhR) which were shown to mediate processes leading to skin hyperpigmentation in response to pollutants by regulation of melanogenic enzymes and transcription factors involved in melanin biosynthesis pathway. In this context, we will discuss a diverse range of New Approach Methodologies (NAMs) capable to provide mechanistic insights of the cellular and molecular pathways involved in the action of environmental stress factors on skin pigmentation and to support the design of raw ingredients and formulations intended to counter their impact and of any subsequently needed clinical studies.

[Skin aging exposome]

The skin is a barrier organ and thus exposed to environmental factors from birth, which essentially determine skin aging. In order to describe and understand this complex process exactly, we applied the concept of the "exposome" to the environmentally induced skin aging process. In this review, we summarize current knowledge on the skin aging exposome. In this context, we characterize the most important exposomal factors, address their relative importance for skin aging and also the relevance of their mutual interactions. Finally, we discuss the clinical consequences resulting from this concept for an effective prevention of skin aging.

Exploring artificial intelligence from a clinical perspective: A comparison and application analysis of two facial age predictors trained on a large-scale Chinese cosmetic patient database

BACKGROUND

Age prediction powered by artificial intelligence (AI) can be used as an objective technique to assess the cosmetic effect of rejuvenation surgery. Existing age-estimation models are trained on public datasets with the Caucasian race as the main reference, thus they are impractical for clinical application in Chinese patients.

METHODS

To develop and select an age-estimation model appropriate for Chinese patients receiving rejuvenation treatment, we obtained a face database of 10 529 images from 1821 patients from the author's hospital and selected two representative age-estimation algorithms for the model training. The prediction accuracies and the interpretability of calculation logic of these two facial age predictors were compared and analyzed.

RESULTS

The mean absolute error (MAE) of a traditional support vector machine-learning model was 10.185 years; the proportion of absolute error ≤6 years was 35.90% and 68.50% ≤12 years. The MAE of a deep-learning model based on the VGG-16 framework was 3.011 years; the proportion of absolute error ≤6 years was 90.20% and 100% ≤12 years. Compared with deep learning, traditional machine-learning models have clearer computational logic, which allows them to give clinicians more specific treatment recommendations.

CONCLUSION

Experimental results show that deep-learning exceeds traditional machine learning in the prediction of Chinese cosmetic patients' age. Although traditional machine learning model has better interpretability than deep-learning model, deep-learning is more accurate for clinical quantitative evaluation. Knowing the decision-making logic behind the accurate prediction of deep-learning is crucial for deeper clinical application, and requires further exploration.

Skin microbiome differentiates into distinct cutotypes with unique metabolic functions upon exposure to polycyclic aromatic hydrocarbons

BACKGROUND

The effects of air pollutants, particularly polycyclic aromatic hydrocarbons (PAHs), on the skin microbiome remain poorly understood. Thus, to better understand the interplay between air pollutants, microbiomes, and skin conditions, we applied metagenomics and metabolomics to analyze the effects of PAHs in air pollution on the skin microbiomes of over 120 subjects residing in two cities in China with different levels of air pollution.

RESULTS

The skin microbiomes differentiated into two cutotypes (termed 1 and 2) with distinct taxonomic, functional, resistome, and metabolite compositions as well as skin phenotypes that transcended geography and host factors. High PAH exposure was linked to dry skin and cutotype 2, which was enriched with species with potential biodegradation functions and had reduced correlation network structure integrity. The positive correlations identified between dominant taxa, key functional genes, and metabolites in the arginine biosynthesis pathway in cutotype 1 suggest that arginine from bacteria contributes to the synthesis of filaggrin-derived natural moisturizing factors (NMFs), which provide hydration for the skin, and could explain the normal skin phenotype observed. In contrast, no correlation with the arginine biosynthesis pathway was observed in cutotype 2, which indicates the limited hydration functions of NMFs and explains the observed dry skin phenotype. In addition to dryness, skin associated with cutotype 2 appeared prone to other adverse conditions such as inflammation.

CONCLUSIONS

This study revealed the roles of PAHs in driving skin microbiome differentiation into cutotypes that vary extensively in taxonomy and metabolic functions and may subsequently lead to variations in skin-microbe interactions that affect host skin health. An improved understanding of the roles of microbiomes on skin exposed to air pollutants can aid the development of strategies that harness microbes to prevent undesirable skin conditions. Video Abstract.

The comparison of the efficacy and safety of fractional 1064 nm Nd:YAG picosecond laser and nonablative fractional 1565 nm laser in the treatment of enlarged pores: A prospective split-face study

BACKGROUND AND OBJECTIVES

To compare the efficacy and safety of fractional 1064 nm Nd:YAG picosecond laser and nonablative fractional 1565 nm laser in the treatment of enlarged pores.

STUDY DESIGN/MATERIALS AND METHODS

Twenty patients received five monthly treatments at months 0, 1, 2, 3, and 4 and were followed up at months 5, 6, and 7. All patients were treated by fractional 1064 nm Nd:YAG picosecond laser (FxPico) on the left face, and nonablative fractional 1565 nm laser (ResurFx) on the right face as a control.

RESULTS

For the 19 patients who completed the study, both sides demonstrated significant improvement on pore counts (p < 0.01), while there was no significant difference between the two sides 3 months after the final treatment (p = 0.092). Excellence rate on the FxPico side (57.9%) was significantly better than the ResurFx side (36.8%) (p < 0.05). Sebum secretion and porphyrin value significantly decreased on both sides after five treatments and there was a higher reduction of sebum level on the ResurFx side. There was no difference between the two therapies in terms of overall satisfaction. Pain of treatment for the ResurFx side (average VAS 4.45 ± 1.60) is significantly higher than that for the FxPico side (average visual analog scale [VAS] 1.48 ± 1.36) (p < 0.001). Erythema, edema, and petechiae were common adverse effects and were mild to moderate. There was significantly higher incidence of hyperpigmentation for the ResurFx side (52.6%) compared with that for the FxPico side (5.3%) (p < 0.001).

CONCLUSION

Fractional 1064 nm Nd:YAG picosecond laser and nonablative fractional 1565 nm laser both are effective, efficient, and safe treatment regimens for enlarged pores, while fractional 1064 nm Nd:YAG picosecond laser has better clinical response with less treatment pain, shorter recovery period and much lower induction of hyperpigmentation.

Assessing the effect of cleansing products on artificially polluted human hairs and skin through in vivo and in vitro models

OBJECTIVE

Based on in vivo data, in vitro models and new methods are created to mimic the impact of aerial pollution onto the hair surface and assess the efficacy of different formulae prototypes.

MATERIAL AND METHODS

Two protocols are developed to mimic the pollution effect, in vitro, on purchased swatches, and in vivo, on scalps and forearms. First, with an artificial sebum mixed with Carbon Black particles, named "sebollution," we evaluated, through an instrumental color measurement, the cleansing efficacy of some shampoo on scalp and hair. The second protocol allowed to assess the interaction between hair care product deposit (shampoo, conditioner, mask, and leave-on) on hair and carbon black particles spread on fiber. The quantification of particle coverage allowed to evaluate the efficiency of a formula to limit the aerial pollution deposit on hair fiber.

RESULTS

To simplify and accelerate the evaluation of 42 shampoo formulae, an extrapolation of the scalp cleaning process was validated on forearm. The respective cleanabilities were calculated and covered a large range of efficacy, from 5%, for a basic bland shampoo generally used to reset swatches, to a strong deep cleansing efficacy of 100%. On hair swatches, cleanability efficiencies of five shampoo were also evaluated to eliminate the deposited of sebollution, in a range of 40%-80%. To quantify the efficacy of preventing the deposition of carbon particle on hair surface, the percentage of coverage of 45 different products was measured, from 2% to 16%. The performance depended of the product category (shampoo, conditioner, mask, and leave-on), driven by the performance of the product deposit, and the capacity of this deposit to interact with aerial pollution.

CONCLUSION

Three new protocols and evaluation methods are proposed to evaluate and quantify the performance of hair care product, to remove/clean, limit, and protect the hair fibers against the aerial pollution that could interact with hair, scalp and sebum. The validation of these approaches was done through the testing of a large panel of hair care product leading to a complete and sincere evaluation of cleansing and anti-deposit efficacy. Combining the knowledge acquired on pollution impact on hair and the development of specific way of evaluation, this work reinforced the rationale of using and developing new cosmetic products that reduced the impact of pollution upon some hair properties.

A systematic review of skin ageing genes: gene pleiotropy and genes on the chromosomal band 16q24.3 may drive skin ageing

Skin ageing is the result of intrinsic genetic and extrinsic lifestyle factors. However, there is no consensus on skin ageing phenotypes and ways to quantify them. In this systematic review, we first carefully identified 56 skin ageing phenotypes from multiple literature sources and sought the best photo-numeric grading scales to evaluate them. Next, we conducted a systematic review on all 44 Genome-wide Association Studies (GWAS) on skin ageing published to date and identified genetic risk factors (2349 SNPs and 366 genes) associated with skin ageing. We identified 19 promising SNPs found to be significantly (p-Value < 1E-05) associated with skin ageing phenotypes in two or more independent studies. Here we show, using enrichment analyses strategies and gene expression data, that (1) pleiotropy is a recurring theme among skin ageing genes, (2) SNPs associated with skin ageing phenotypes are mostly located in a small handful of 44 pleiotropic and hub genes (mostly on the chromosome band 16q24.3) and 32 skin colour genes. Since numerous genes on the chromosome band 16q24.3 and skin colour genes show pleiotropy, we propose that (1) genes traditionally identified to contribute to skin colour have more than just skin pigmentation roles, and (2) further progress towards understand the development of skin pigmentation requires understanding the contributions of genes on the chromosomal band 16q24.3. We anticipate our systematic review to serve as a hub to locate primary literature sources pertaining to the genetics of skin ageing and to be a starting point for more sophisticated work examining pleiotropic genes, hub genes, and skin ageing phenotypes.

The Damaging Effects of Long UVA (UVA1) Rays: A Major Challenge to Preserve Skin Health and Integrity

Within solar ultraviolet (UV) light, the longest UVA1 wavelengths, with significant and relatively constant levels all year round and large penetration properties, produce effects in all cutaneous layers. Their effects, mediated by numerous endogenous chromophores, primarily involve the generation of reactive oxygen species (ROS). The resulting oxidative stress is the major mode of action of UVA1, responsible for lipid peroxidation, protein carbonylation, DNA lesions and subsequent intracellular signaling cascades. These molecular changes lead to mutations, apoptosis, dermis remodeling, inflammatory reactions and abnormal immune responses. The altered biological functions contribute to clinical consequences such as hyperpigmentation, inflammation, photoimmunosuppression, sun allergies, photoaging and photocancers. Such harmful impacts have also been reported after the use of UVA1 phototherapy or tanning beds. Furthermore, other external aggressors, such as pollutants and visible light (Vis), were shown to induce independent, cumulative and synergistic effects with UVA1 rays. In this review, we synthetize the biological and clinical effects of UVA1 and the complementary effects of UVA1 with pollutants or Vis. The identified deleterious biological impact of UVA1 contributing to clinical consequences, combined with the predominance of UVA1 rays in solar UV radiation, constitute a solid rational for the need for a broad photoprotection, including UVA1 up to 400 nm.

A dermocosmetic formulation containing Vichy volcanic mineralizing water, Vitreoscilla filiformis extract, niacinamide, hyaluronic acid, and vitamin E regenerates and repairs acutely stressed skin

The exposome has an impact on skin from life-long exposure. Acute short-term exposure to exposome stressors can also alter skin functions such as skin physical barrier and immune defenses, leading to skin dryness, sensitivity, flares of inflammatory skin conditions, or viral reactivations. Probiotics are defined as live microorganisms, which, when administered in adequate amounts, confer a health benefit on the host. An extract produced by lysing Vitreoscilla filiformis (VfeV) cultured in Vichy volcanic mineralizing water (VVMW) has properties of probiotic fractions. In this review, we present in vivo and ex vivo studies with a dermocosmetic formulation containing 80% VVMW, 5% VfeV, 4% niacinamide (vitamin B3), 0.4% hyaluronic acid, and 0.2% vitamin E (M89PF) to evaluate the clinical efficacy in preventing and repairing stressed skin. Skin barrier benefits of M89PF were shown in studies after the skin was exposed to sudden thermal changes, after skin irritation by tape stripping, and in sleep-deprived women. M89PF significantly accelerated skin renewal compared to untreated skin. Skin antioxidant defense activity of M89PF was shown after exposure to stress from UVA plus cigarette smoke aggression. Skin microbiome recovery after acute stress from a harsh cleanser was significantly better in M89PF-treated skin compared to bare skin. Clinical benefits of M89PF on correcting clinical signs of stressed skin were shown in both Caucasian and Asian women exposed to a stressful lifestyle and various external (pollution, tobacco smoking, solar radiation) and internal (poor sleep, stressful work, unbalanced diet, and alcohol consumption) exposome factors. M89PF also showed depigmenting properties on dark spots in Asian women. Further clinical studies are now warranted to evaluate the efficacy of M89PF as adjuvant care to prevent and repair skin barrier disruption and reinforce skin defenses in skin exposed to acute stresses.

Defining skin aging and its risk factors: a systematic review and meta-analysis

Skin aging has been defined to encompass both intrinsic and extrinsic aging, with extrinsic aging effected by environmental influences and overlaying the effects of chronological aging. The risk factors of skin aging have been studied previously, using methods of quantifying skin aging. However, these studies have yet to be reviewed. To better understand skin aging risk factors and collate the available data, we aimed to conduct a systematic review and meta-analysis. We conducted our systematic review in compliance with Preferred Reporting Item for Systematic Review and Meta-Analyses (PRISMA) guidelines. Embase, PubMed and Web of Science databases were searched in October 2020 using specific search strategies. Where odds ratios were reported, meta-analyses were conducted using the random effects model. Otherwise, significant factors were reported in this review. We identified seven notable risk factors for various skin aging phenotypes: age, gender, ethnicity, air pollution, nutrition, smoking, sun exposure. This review's results will guide future works, such as those aiming to examine the interaction between genetic and environmental influences.

Standardized Terminalia chebula Fruit Extract: A Natural Ingredient That Provides Long-Lasting Antioxidant Protection and Reverses Visible Signs of Pollution-Induced Skin Damage

Background

Identification of long-lasting natural antioxidants to protect against and repair skin damage induced by exposure to environmental pollution is in high demand.

Objective

To investigate a standardized Terminalia chebula (TC) fruit extract for its long-lasting antioxidant and anti-inflammatory properties and its ability to reverse the visible signs of pollution-induced skin damage in an 8-week clinical study.

Material and Methods

Chemical and cell-based in vitro studies were performed to characterize long-lasting antioxidant and anti-inflammatory properties; a clinical study with subjects with normal to dry skin living in a high-pollution city for the previous 5 years was conducted to assess if a formulation containing 1% standardized TC fruit extract affected significant improvements in skin’s visible condition and appearance compared with its placebo.

Results

The standardized TC fruit extract provided longer-lasting and more efficient neutralization of reactive oxygen species (ROS) than tocopherol; treatment of keratinocytes with the fruit extract prior to being stressed with urban dust safeguarded against increases in intracellular ROS, inhibited release of inflammatory cytokines IL-6 and IL-8 and protected membrane lipids against peroxidation. A clinical study yielded statistically significant improvements in dermatologist scores and subject self-assessments for skin texture, hydration, tone, firmness and radiance as compared to its placebo.

Conclusion

These studies validate the use of this standardized TC fruit extract not only as a restorative to diminish visible signs of existing damage but also as a preventative to help defend skin against damages caused by chronic exposure to environmental pollution.

Polycyclic aromatic hydrocarbons regulate the pigmentation pathway and induce DNA damage responses in keratinocytes, a process driven by systemic immunity

BACKGROUND

Urban pollution is correlated with an increased prevalence of skin pigmentation disorders, however the physiological processes underlying this association are unclear.

OBJECTIVES

To delineate the relationship between polycyclic aromatic hydrocarbons (PAHs), a key constituent of atmospheric pollution, and immunity/skin pigmentation pathways.

METHODS

We exposed peripheral blood mononuclear cells (PBMC) to PAHs and performed cytokines/chemokine profiling. We then examined the effect of immune activation on pigmentation by co-culturing PBMC and Benzo(a)pyrene (BaP) with reconstructed human pigmented epidermis (RHPE). To study the mechanism, we treated keratinocytes with conditioned medium from BaP-exposed PBMC and studied DNA damage responses, aryl hydrocarbon receptor (AhR) activation and pro-pigmentation factor, proopiomelanocortin (POMC) secretion.

RESULTS

PAHs induced up-regulation of inflammatory cytokines/chemokine in PBMC. Co-culturing of RHPE with PBMC+BaP resulted in increased melanin content and localization. BaP-conditioned medium significantly increased DNA damage, p53 stabilization, AhR activation and POMC secretion in keratinocytes. We found that IFNγ induced DNA damage, while TNFα and IL-8 potentiated POMC secretion in keratinocytes. Importantly, BaP-conditioned medium-induced DNA damage and POMC secretion is prevented by antioxidants vitamin E, vitamin C and sulforaphane, as well as the prototypical corticosteroid dexamethasone. Finally, vitamin C and sulforaphane enhanced the genome protective and depigmentation effects of dexamethasone, providing proof-of-concept for a combinatorial approach for the prevention and/or correction of PAH-induced pigment spots formation.

CONCLUSION

Our study reveals the importance of systemic immunity in regulating PAH-induced skin pigmentation, and provide a new keratinocyte DNA damage response mechanistic target for the prevention or reversal of pollution-associated skin pigmentation.

Air pollution-induced tanning of human skin

BACKGROUND

Melanism is more frequent in animals living in polluted areas on urban-industrial sites. Given that an increasing number of people are exposed to elevated air pollution levels, it is possible that environmental pollutants affect melanogenesis in human skin. Epidemiological studies have shown that exposure to traffic-related air pollutants such as diesel exhaust particles (DEP) is associated with more clinical signs of hyperpigmentation. However, mechanistic evidence linking DEP exposure to pigmentation has been elusive.

OBJECTIVES

To develop an ex vivo skin model to allow for repetitive topical application of relevant ambient DEP, and to provide proof of concept in humans.

METHODS

We measured skin pigmentation, melanin and pigmentation-associated gene expression, and evaluated oxidative stress.

RESULTS

Repetitive exposure of ex vivo skin to DEP at nontoxic concentrations increased skin pigmentation. This increase was visible to the naked eye, time dependent, and associated with an increase in melanin content and the transcription of genes involved in de novo melanin synthesis. Similarly, in healthy participants (n = 76), repetitive topical application of DEP at nontoxic concentrations increased skin pigmentation. DEP-induced pigmentation was mediated by an oxidative stress response. After the application of DEP, epidermal antioxidants were depleted, lipid peroxidation and oxidative DNA damage were enhanced, and in a vehicle-controlled, double-blind clinical study DEP-induced pigmentation was prevented by the topical application of an antioxidant mixture.

CONCLUSIONS

Similar to solar radiation, air pollutants cause skin tanning. As eumelanin is an antioxidant, it is proposed that this response serves to protect human skin against air pollution-induced oxidative stress.

Clinical and biological impact of the exposome on the skin

The skin exposome is defined as the totality of environmental exposures over the life course that can induce or modify various skin conditions. Here, we review the impact on the skin of solar exposure, air pollution, hormones, nutrition and psychological factors. Photoageing, photocarcinogenesis and pigmentary changes are well-established consequences of chronic exposure of the skin to solar radiation. Exposure to traffic-related air pollution contributes to skin ageing. Particulate matter and nitrogen dioxide cause skin pigmentation/lentigines, while ozone causes wrinkles and has an impact on atopic eczema. Human skin is a major target of hormones, and they exhibit a wide range of biological activities on the skin. Hormones decline with advancing age influencing skin ageing. Nutrition has an impact on numerous biochemical processes, including oxidation, inflammation and glycation, which may result in clinical effects, including modification of the course of skin ageing and photoageing. Stress and lack of sleep are known to contribute to a pro-inflammatory state, which, in turn, affects the integrity of extracellular matrix proteins, in particular collagen. Hormone dysregulation, malnutrition and stress may contribute to inflammatory skin disorders, such as atopic dermatitis, psoriasis, acne and rosacea.

Skin exposome science in practice : current evidence on hair biomonitoring and future perspectives

The skin exposome, defined as the totality of environmental exposures from conception to death that can induce or modify various skin conditions, compiles environmental, lifestyle and psychosocial exposures, as well as the resulting internal biological and physiological responses to these exposures. Biomonitoring can be used to obtain information on the internal dose of pollutants. The concentration of biomarkers in body fluids is highly variable over time due to differential elimination kinetics of chemicals, whereas they accumulate in hair. Hair analysis thus provides information on cumulative exposure over a longer period of time, and so can be used for assessing chronic exposure to pollutants. Studies on hair samples collected from 204 women living in two cities in China with different levels of pollution demonstrated that hair damage and the skin microbiome are biomarkers of a polluted city and long-term exposure to pollution and UV can increase signs of facial ageing. Adopting an exposome approach to skin health requires assessing multiple exposures and biological consequences, possibly in relation to longitudinally followed-up health outcomes. Leveraging "omics" data (e.g. metabolomics, proteomics, genomics and microbiome) and big data analytics, in particular multivariate analysis, will help to further understand the impact of pollution on skin and the combined effects with other exposome factors, including solar radiation and other environmental exposures.

Daily photoprotection to prevent photoaging

BACKGROUND

Extrinsic skin aging or photoaging was previously thought to be almost exclusively due to solar ultraviolet (UV) radiation. However, recent literature has described other contributing factors and clarification is thus required as to what extent and what type of daily photoprotection is needed to mitigate extrinsic skin aging.

METHODS

We reviewed the existing scientific evidence on daily photoprotection, and specific requirements at the product level, to prevent extrinsic skin aging. We critically reviewed the existing evidence on potential ecological and toxicological risks which might be associated with daily photoprotection.

RESULTS

Evidence shows that broad protection against the entire solar range of UVB, UVA, UVA1, visible light, and short infrared (IRA) is required to prevent extrinsic aging. Other exposome factors, such as air pollution and smoking, also contribute to skin aging. Daily broad-spectrum sunscreen photoprotection should thus contain antioxidant ingredients for additional benefits against UV, IRA, and pollution-induced oxidative stress as well as anti-aging active ingredients to provide clinical benefits against skin aging signs, such as wrinkles and dark spots. Broad-spectrum sunscreen containing pigments, such as iron oxide, may be required for melasma prevention. There is no conclusive clinical evidence that daily sunscreen use is unsafe or that it compromises vitamin D synthesis.

CONCLUSION

Daily use of broad-spectrum sunscreen containing antioxidant and anti-aging active ingredients can effectively reduce extrinsic aging.

Environmentally-Induced (Extrinsic) Skin Aging: Exposomal Factors and Underlying Mechanisms

As a barrier organ, the skin is an ideal model to study environmentally-induced (extrinsic) aging. In this review, we explain the development of extrinsic skin aging as a consequence of skin exposure to specific exposomal factors, their interaction with each other, and the modification of their effects on the skin by genetic factors. We also review the evidence that exposure to these exposomal factors causes extrinsic skin aging by mechanisms that critically involve the accumulation of macromolecular damage and the subsequent development of functionally altered and/or senescent fibroblasts in the dermal compartment of the skin.

A new procedure, free from human assessment, that automatically grades some facial skin signs in men from selfie pictures. Application to changes induced by a severe aerial chronic urban pollution

OBJECTIVE

These were two folds: at first, to develop an automatic grading system specifically dedicated to some facial signs of men, similar to the one previously validated on women of different ethnic ancestry and second, to assess its potential in detecting and grading the possible impacts of a severe aerial urban pollution on some facial signs of Chinese men.

METHODS

In both studies, selfie images were obtained from differently aged men. Nine facial signs were automatically graded through a specific A.I-based algorithm and clinically assessed by a panel of experts and dermatologists. Selfie pictures were taken from individual smartphones of variable optical properties. The first study, designed for developing an automatic grading system, involved three comparable cohorts of men from three different regional ancestries (African, Asian, Caucasian, 110 each) the selfie images of which were acquired under four different lighting conditions. As a second use case study, the facial signs of two cohorts of Chinese men (101 and 100, each), differently aged, regularly exposed to very different aerial urban pollution conditions (UP) were analysed by the same algorithm, selfies being taken under only one lighting condition.

RESULTS

-The new automatic grading system of facial signs suits well to men, showing comparable results than that the one dedicated to women and provides data in close agreement with experts' assessments. -In both cases (expert's or automatic methodology), the accuracy of the scores appeared ethnic-dependent. -The applied case confirmed previous results obtained clinically, that is, that many facial signs were found of an increased severity among men exposed to a severe urban pollution, as compared to those living in a less polluted city. -In both studies, statistical agreements between the automatic grading system and expert's assessments were reached. In some facial signs, the automatic grading system seems offering a slightly better accuracy than the assessments made by the experts.

CONCLUSION

Apart from some minor limitations, this A.I-based automatic grading system, free from human intervention, performed as well as the one previously developed in women, in close agreement with expert's assessments. In epidemiological studies, this system offers an easy, fast, affordable and confidential approach in the detection and quantification of male facial signs.

The Skin Interactome: A Holistic "Genome-Microbiome-Exposome" Approach to Understand and Modulate Skin Health and Aging

Higher demands on skin care cosmetic products for strong performance drive intense research to understand the mechanisms of skin aging and design strategies to improve overall skin health. Today we know that our needs and influencers of skin health and skin aging change throughout our life journey due to both extrinsic factors, such as environmental factors and lifestyle factors, as well as our intrinsic factors. Furthermore, we need to consider our microflora, a collection of micro-organisms such as bacteria, viruses, and fungi, which is a living ecosystem in our gut and on our skin, that can have a major impact on our health. Here, we are viewing a holistic approach to understand the collective effect of the key influencers of skin health and skin aging both reviewing how each of them impact the skin, but more importantly to identify molecular conjunction pathways of these different factors in order to get a better understanding of the integrated “genome-microbiome-exposome” effect. For this purpose and in order to translate molecularly the impact of the key influencers of skin health and skin aging, we built a digital model based on system biology using different bioinformatics tools. This model is considering both the positive and negative impact of our genome (genes, age/gender), exposome: external (sun, pollution, climate) and lifestyle factors (sleep, stress, exercise, nutrition, skin care routine), as well as the role of our skin microbiome, and allowed us in a first application to evaluate the effect of the genome in the synthesis of collagen in the skin and the determination of a suitable target for boosting pro-collagen synthesis. In conclusion, we have, through our digital holistic approach, defined the skin interactome concept, as an advanced tool to better understand the molecular genesis of skin aging and further develop a strategy to balance the influence of the exposome and microbiome to protect, prevent, and delay the appearance of skin aging signs and preserve good skin health condition. In addition, this model will aid in identifying and optimizing skin treatment options based on external triggers, as well as helping to design optimal treatments modulating the intrinsic pathways.

Air Pollution and Skin Aging

PURPOSE OF THE REVIEW

The evidence on the role of air pollution on skin aging has increased in recent years. The accumulating evidence is based on both, epidemiological and mechanistic studies. The purpose of this review is to evaluate the recent evidence on the impacts of air pollution on skin aging as well as identify knowledge gaps for future research.

RECENT FINDINGS

Traffic-related air pollution exposure (particulate matter (PM), soot and nitrogen dioxide (NO₂)) has been associated with premature skin aging in several independent cohorts. In real life, human skin is additionally exposed to UV radiation, which is known for its effects on premature skin aging. More recent epidemiological findings suggest that (1) associations of PM can be altered by UV radiation with stronger PM associations at lower levels of UV, and (2) there is an association of tropospheric ozone with wrinkle formation, independent of NO₂, PM, and UV. The association between traffic-related air pollution and skin aging has been well-established. More recent epidemiological studies focused on the associations with ozone as well as interactions with of ambient air pollution with UV radiation, a research area that is becoming more important with the increase of global warming.

Changes in facial signs due to age and their respective weights on the perception of age and skin plumpness among differently aged Korean women

OBJECTIVE

To determine the respective weights of certain facial signs on the assessment of perceived age and plumpness on Korean women of different ages.

MATERIAL AND METHODS

Photographs were taken of the faces of 112 Korean women of different ages (18-80 years) under standardized conditions. These photographs allowed to focus and define 19 facial signs, which were then graded by 15 experts and dermatologists, using standardized scales provided by a reference Skin Aging Atlas. The facial signs were dispatched into 5 clusters, namely Wrinkles/Texture, Ptosis/Sagging, Pigmentation disorders, Vascular disorders, and Cheek skin pores. A naïve panel, composed of 92 Korean women, of similar age range were asked, when viewing full-face photographs, to: (a) attribute on a 0-10 scale their perception of the skin plumpness (ie supple/hydrated/nourished) and (b) estimate the age of the subject.

RESULTS

With the exception of Vascular disorders, the severity of all 4 clusters increased with age, although at different rates. The Wrinkles/Texture or Ptosis/Sagging showed a rather regular progression. Although perceived ages and real ages were found highly correlated, half of the subjects were judged older by 2-12 years. The facial signs/clusters were significantly correlated with perceived age, with the exceptions of vascular disorders, size of pigmentary spots and cheek skin pores. The weights in perceived ages of Wrinkles/Texture and Ptosis/Sagging represent 37% each and Pigmentation disorders at 26%. Skin plumpness was logically found significantly anti-correlated with perceived age. If, surprisingly, Vascular disorders were found not impacting the plumpness aspect, Cheek skin pores presented a clear influence.

CONCLUSION

Within facial clinical clusters, Wrinkles/Texture, Ptosis/Sagging, and Pigmentation disorders are major factors in the assessment of perceived age in Korean women. The perception of a decreased skin plumpness is significantly associated with increased perceived age.

Changes in facial signs due to age and their respective weights on the perception of age, on a tired-look or a healthy glow among differently aged Chinese men

OBJECTIVE

To determine the respective weights of certain facial signs on the assessment of perceived age, tired-look and healthy glow on Chinese men of different ages.

MATERIAL AND METHODS

Photographs were taken of the faces of 420 Chinese men of different ages, under standardized conditions. These photographs allowed to focus and define 15 facial signs, which were then graded by 15 experts and dermatologists, using standardized scales provided by a reference Skin Aging Atlas. The facial signs were dispatched into 5 clusters, namely wrinkles/texture, ptosis/sagging, pigmentation disorders, vascular disorders and cheek skin pores. A naïve panel, composed of 80 Chinese women, of similar age range were asked, when viewing full-face photographs, to: (i) attribute on a 0-10 scale their perception of both the tired-look and healthy glow aspects and (ii) estimate the age of the subject.

RESULTS

With the exception of vascular disorders, the severity of all 4 clusters increased with age, although at different rates. The ptosis/sagging or pigmentation disorders showed a rather regular progression. Although perceived ages and real ages were found to be closely correlated, the vast majority of subjects were judged older by 2-10 years. The changes in facial signs (and their related clusters) were significantly correlated with perceived age, with the exceptions of skin spot density and cheek skin pores. Although the aspects of tired-look and healthy glow were logically found to be anti-correlated, tired-look was more statistically associated with perceived age for the five clusters. Signs of eye contour appear to be closely correlated with the perception of a tired-look.

CONCLUSION

Within facial clinical clusters, wrinkles/texture and ptosis/sagging are major factors in the assessment of perceived age in Chinese men. Tired-look appears to be strongly associated with perceived age.

Evaluating the respective weights of some facial signs on perceived ages in differently aged women of five ethnic origins

BACKGROUND

New gratification assessments, after skincare routines or makeup products, could benefit from innovative methods that could predict the culturally based perceptions of age.

AIMS

To determine the facial signs that most influence the perception of age in women of five different ethnic ancestries, assessed by the same ethnical naïve panel.

PATIENTS/METHODS

The faces of 1351 women, differently aged (18-80 years), from five countries (China, France, India, Japan, and South Africa) were photographed under the same standardized conditions in the five countries. Fourteen to 24 facial signs (grouped under five clusters, ie, Wrinkles/Texture, Ptosis/Sagging, Pigmentation disorders, Vascular disorders, and Cheeks skin pores) were focused, and their respective severities were graded using referential Skin Aging Atlases by the same panel of 15 experts and dermatologists. Five naïve panels, all comprising 100 local women, allowed to collect the perceived age, assessed from blind-coded full-face photographs.

RESULTS

Although perceived ages and real ages were found highly correlated, their differences vary according to ethnicities, particularly among a large part of Indian and South African women, judged older by about 5 and 7 years, respectively. Results show that the clusters of Wrinkles/Texture and Ptosis/Sagging are predominant factors taken into account in almost all ethnicities, albeit at various extents, reaching almost 100% in French women. Pigmentation disorders appear important secondary factors in Japanese, South African, and Indian women. Vascular disorders, of a difficult grading in darker skin tones, were found of some impact in Japanese and Chinese women. Cheek skin pores were of minor or nil weight in the attribution of age, at the exception of South African women. Regarding facial areas which drive aging perception, it seems the upper-half face has prevalence for Chinese and Japanese women whereas the lower-half face has major importance for South African women.

CONCLUSION

Facial traits are differently perceived as signs of aging according to un-separable ethnic ancestries and cultural factors.

Changes of the human skin microbiota upon chronic exposure to polycyclic aromatic hydrocarbon pollutants

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are of environmental and public health concerns and contribute to adverse skin attributes such as premature skin aging and pigmentary disorder. However, little information is available on the potential roles of chronic urban PAH pollutant exposure on the cutaneous microbiota. Given the roles of the skin microbiota have on healthy and undesirable skin phenotypes and the relationships between PAHs and skin properties, we hypothesize that exposure of PAHs may be associated with changes in the cutaneous microbiota. In this study, the skin microbiota of over two hundred Chinese individuals from two cities in China with varying exposure levels of PAHs were characterized by bacterial and fungal amplicon and shotgun metagenomics sequencing.

RESULTS

Skin site and city were strong parameters in changing microbial communities and their assembly processes. Reductions of bacterial-fungal microbial network structural integrity and stability were associated with skin conditions (acne and dandruff). Multivariate analysis revealed associations between abundances of Propionibacterium and Malassezia with host properties and pollutant exposure levels. Shannon diversity increase was correlated to exposure levels of PAHs in a dose-dependent manner. Shotgun metagenomics analysis of samples (n = 32) from individuals of the lowest and highest exposure levels of PAHs further highlighted associations between the PAHs quantified and decrease in abundances of skin commensals and increase in oral bacteria. Functional analysis identified associations between levels of PAHs and abundance of microbial genes of metabolic and other pathways with potential importance in host-microbe interactions as well as degradation of aromatic compounds.

CONCLUSIONS

The results in this study demonstrated the changes in composition and functional capacities of the cutaneous microbiota associated with chronic exposure levels of PAHs. Findings from this study will aid the development of strategies to harness the microbiota in protecting the skin against pollutants. Video Abstract.

Gender-related differences in the facial aging of Caucasian French subjects and their relations with perceived ages and tiredness

OBJECTIVES

(a) To assess and compare the changes in five facial signs with age between genders of Caucasian subjects and (b) to evaluate their links with perceived ages and tiredness.

MATERIAL AND METHODS

Once zoomed from standardized digital photographs, five facial signs of 518 Caucasian French subjects of both genders and different ages (18-69 years) were graded by 15 experts, using a referential Skin Aging Atlas. A large naïve panel of 1000 French subjects (500 men and 500 women) was asked to attribute a perceived age and a degree of tiredness to 200 subjects (among the 518).

RESULTS

The severity of the facial signs increases with time at a linear-like rate. The changes in marionette lines significantly differ between genders, much more pronounced in women, and nasolabial fold was found more pronounced in men at older ages (>50 years). Before 50's, Forehead wrinkles present a slightly higher severity in men whereas at 50's women present more severe ptosis. Crow's feet wrinkles did not show significant changes. Perceived ages were found significantly correlated with the severities of the facial signs and the perception of tiredness was associated with perceived ages in men, but not in women older than 40 years. The gender-related perceptions from the naïve panel in both perceived ages and tiredness showed a low discrepancy. Interestingly, as for changes in facial signs, the upper-half face seems more affected for men and lower-half face for women; after 40 years, the naïve panel seems more focusing on the same areas to predict a perceived age.

CONCLUSION

As compared to the previous Chinese study, the present work reveals some slight ethnical-related differences, indicating that the facial signs of the lower face play a major role in the assessment of perceived age of both genders from different ethnicity.

Assessing the impact of an aerial chronic urban pollution (UP) on some facial signs of differently-aged Chinese men

OBJECTIVE

To assess the impact of an aerial chronic urban pollution (UP) on the severities of some facial signs of Chinese men living in two close but differently polluted Chinese cities.

MATERIALS AND METHODS

Standardized digital photographs were taken on 201 subjects from two cohorts of Chinese men (100 inhabitants of Baoding/very polluted and 101 inhabitants of Dalian/less polluted) differently aged (20-60 years) allowing a focus on 17 different facial signs. The latter were graded by 15 experts, using a clinical referential skin atlas. A questionnaire was filled by all subjects collecting their habits and uses with regard sun-exposures and skincare products. A naïve panel of 80 Chinese women, of comparable ages, attributed a perceived age to each subject under blind conditions.

RESULTS

These confirm previous data obtained on Chinese women, with a similar protocol, i.e. that some facial signs show an increased severity in the more polluted city. However, changes in facial signs, with age, are of a different pattern according to gender. In Chinese men, most signs show early onsets with however low age-related changes, inversely to those observed in women, at the exception of vascular disorders. Habits of sun-exposures and uses of skincare product were found totally similar in both cohorts, reinforcing the specific role of UP in the progressive changes of facial signs. Similar to the results previously obtained on Chinese women, men living in a more polluted city were judged older than those living in a less polluted aerial environment.

CONCLUSION

The present work confirms that a more severe UP increases the severities of some facial signs in Chinese men.

Distinct Habits Of Sun Exposures Lead To Different Impacts On Some Facial Signs Of Chinese Men Of Different Ages

OBJECTIVE

To clinically evaluate the impacts of sun exposures on some facial signs of differently aged Chinese men with a distinct behavior vis à vis sun exposures.

METHODS

Two comparable cohorts of Chinese men (aged 18-75 years old), living in two cities (Shanghai, Hong Kong) were created according to their usual behavior towards sun exposure and through their variable use(s) of a photo-protective product, i.e. non-sun-phobic (N = 127) and sun-phobic (N = 134). Standard photographs (full-face and 45° lateral) allowed to focus on 13 facial signs that were further graded by 15 experts and dermatologists, using a referential Skin Aging Atlas. Absolute differences in the scores of each sign were used (non-sun-phobic minus sun-phobic), by age-classes, to better ascertain the impact of sun exposures and a photo-protecting product, when used.

RESULTS

Most facial signs, particularly wrinkles and skin texture, differentiated the two cohorts. Some others showed some erratic changes with age, albeit more pronounced at older ages. In contrast with previous results obtained in Chinese women, the changes observed in men were not only of a lessened severity but were undetected at early ages (<30 years old). Overall, these different behaviors with regard to sun exposures led to significant differences in the facial signs of Chinese men. The latter can be illustrated by two virtual morphings that combine the impacts of both intrinsic and extrinsic aging processes.

CONCLUSION

The present work illustrates, for the first time, some specificities of the impacts of sun exposures on the facial skin of Chinese men, more expressed at older ages, inversely to those observed in Chinese women, occurring at younger ages.

Potential role of PM2.5 in melanogenesis

Ambient particulate matter 2.5 (PM_2.5) is one of the main components of air pollutants, which can absorb many polycyclic aromatic hydrocarbons and metals. The effect of PM_2.5 on human skin and its biological significance in skin homeostasis remain incompletely understood. Previous studies demonstrated that PM_2.5 can activate aryl hydrocarbon receptor (AhR), generate reactive oxygen species, and induce skin inflammation. These processes may be involved in melanocyte homeostasis and melanogenesis. We hypothesize that AhR signaling may be responsible for PM_2.5-related hyperpigmentation.

A novel multifunctional skin care formulation with a unique blend of antipollution, brightening and antiaging active complexes

BACKGROUND

High demand on anti-aging skin care encourage the improvement and development of more personalized formulations with additional benefits for general skin health and age associated skin signs. The skin aging physical and biological phenotypes manifest differently between diverse ethnic populations. A highly polluted environment can be viewed as an extrinsic factor accelerating the skin aging process.

AIM

To develop a unique formula with active complexes, having multifunctional effects for anti-pollution, brightening and anti-aging/barrier strengthening purposes with confirmed activities in vitro and ex vivo skin models, suitable for polluted skin.

METHODS

In vitro culture model with primary human skin cells, ex vivo studies with full-thickness human skin, melanocyte 3D coculture model, gene expression of epidermal and dermal genes, anti-glycation, proteasomal activity, melanin, and cytokine assays.

RESULTS

In vitro and ex vivo studies clearly demonstrated that diglucosyl gallic acid (active A) and the formulation complex inhibited pollution mediated MMP1 protein, CYP1A1 gene expression, and IL-6 protein secretion, while caprylic/capric triglyceride, diacetyl boldine (active B) had anti-melanogenic effect in in vitro primary melanocyte monoculture and 3D spheroid model. Another active compound, acetyl dipeptide 1 cetyl ester (active D), significantly upregulated epidermal barrier genes (Aquaporin 3 [AQP3], Filaggrin [FLG], caspase 14, and keratin 10) in human primary keratinocytes. Interestingly, both acetyl dipeptide 1 cetyl ester (active D) and niacinamide (active C) improved dermal gene expression (fibrillin-1, Collagen type 1 alpha 1, Decorin, Lysyl oxidase-like 1) and, moreover, had significant anti-glycant and proteasomal promoter activity in human primary fibroblasts.

CONCLUSION

Considering consumers need in heavily polluted areas, we developed a multipurpose formulation comprised of unique active complexes toward pollution, pollution induced inflammation, skin brightening, and antiaging concerns with beneficial results demonstrated by in vitro and ex vivo studies.

A new procedure, free from human assessment that automatically grades some facial skin structural signs. Comparison with assessments by experts, using referential atlases of skin ageing

OBJECTIVE

To develop an automatic system that grades the severity of facial signs through 'selfies' pictures taken by women of different ages and ethnics.

METHODS

1140 women from three ethnics (African-American, Asian, Caucasian), of different ages (18-80 years old), took 'selfies' by high resolution smartphones cameras under different conditions of lighting or facial expressions. A dedicated software, was developed, based on a Convolutional Neural Network (CNN) that integrates training data from referential Skin Aging Atlases. The latter allows to an immediate quantification of the severity of nine facial signs according to the ethnicity declared by the subject. These automatic grading were confronted to those assessed by 12 trained experts and dermatologists either on 'selfies' pictures or in live conditions on a smaller cohort of women.

RESULTS

The system appears weakly influenced by lighting conditions or facial expressions (coefficients of variations ranging 10-13% for most signs) and leads to global agreements with experts' assessments, even showing a better reproducibility on some facial signs.

CONCLUSION

This automatic scoring system, still in development, seems offering a new quantitative approach in the quantified description of facial signs, independent from human vision, in many applications, being individual, cosmetic oriented or dermatological with regard to the follow-up of medical anti-ageing corrective strategies.