The role of air pollutants in atopic dermatitis

Prenatal risk factors of indoor environment and incidence of childhood eczema in the Japan Environment and Children's Study

The quality of indoor environment is a risk factor for early childhood eczema and atopic dermatitis; however, its influence during pregnancy on childhood eczema in Japan has not been investigated. In this study, we aimed to determine the indoor environmental factors that are associated with eczema in children up to 3 years of age, using national birth cohort data from the Japan Environment and Children's Study (JECS). Information on indoor environments and eczema symptoms until 3 years of age was collected using self-administered questionnaires to the mothers. A total of 71,883 and 58,639 mother-child pairs at 1.5- and 3-years-old, respectively, were included in the former analyses. To account for prenatal indoor risk factors, 17,568 (1.5-years-old) and 7063 (3-years-old) children without indoor mold and/or ETS exposure were included in the final analysis. A higher mold index, gas heater use, parquet flooring use, and frequent insecticide use showed significantly increased risks for childhood eczema up to 3 years of age. These associations were consistent after stratification analysis among children whose parents did not have a history of allergies. The updated WHO guidelines on indoor air quality should be implemented based on recent findings regarding the effects of prenatal exposure to indoor dampness on health effects of children further in life, including asthma, respiratory effects, eczema, and other immunological effects.

Association between exposure to ambient air pollution, meteorological factors and atopic dermatitis consultations in Singapore-a stratified nationwide time-series analysis

Atopic dermatitis (AD) is a chronic inflammatory skin disease affecting approximately 20% of children globally. While studies have been conducted elsewhere, air pollution and weather variability is not well studied in the tropics. This time-series study examines the association between air pollution and meteorological factors with the incidence of outpatient visits for AD obtained from the National Skin Centre (NSC) in Singapore. The total number of 1,440,844 consultation visits from the NSC from 2009 to 2019 was analysed. Using the distributed lag non-linear model and assuming a negative binomial distribution, the short-term temporal association between outpatient visits for AD and air quality and meteorological variability on a weekly time-scale were examined, while adjusting for long-term trends, seasonality and autocorrelation. The analysis was also stratified by gender and age to assess potential effect modification. The risk of AD consultation visits was 14% lower (RR10th percentile: 0.86, 95% CI 0.78-0.96) at the 10th percentile (11.9 µg/m3) of PM2.5 and 10% higher (RR90th percentile: 1.10, 95% CI 1.01-1.19) at the 90th percentile (24.4 µg/m3) compared to the median value (16.1 µg/m3). Similar results were observed for PM10 with lower risk at the 10th percentile and higher risk at the 90th percentile (RR10th percentile: 0.86, 95% CI 0.78-0.95, RR90th percentile: 1.10, 95% CI 1.01-1.19). For rainfall for values above the median, the risk of consultation visits was higher up to 7.4 mm in the PM2.5 model (RR74th percentile: 1.07, 95% CI 1.00-1.14) and up to 9 mm in the PM10 model (RR80th percentile: 1.12, 95% CI 1.00-1.25). This study found a close association between outpatient visits for AD with ambient particulate matter concentrations and rainfall. Seasonal variations in particulate matter and rainfall may be used to alert healthcare providers on the anticipated rise in AD cases and to time preventive measures to reduce the associated health burden.

An Overview on Atopic Dermatitis, Oxidative Stress, and Psychological Stress: Possible Role of Nutraceuticals as an Additional Therapeutic Strategy

Atopic dermatitis (AD) is a chronic inflammatory skin condition with a considerable impact on patients' quality of life. Its etiology is multifactorial and, among the predisposing factors, a role is played by oxidative stress. Pollution, recurrent infections, and psychological stress contribute to oxidative stress, amplifying the production of proinflammatory cytokines and worsening barrier damage. There are various oxidative stress mechanisms involved in the pathogenesis of AD. Moreover, AD often appears to be associated with psychological disorders such as alexithymia, depression, and anxiety due to severe itching and related insomnia, as well as social distress and isolation. The increasing incidence of AD requires the evaluation of additional therapeutic approaches in order to reduce the psychological burden of this condition. Our review aims to evaluate the role of some nutraceuticals in AD treatment and its related psychological comorbidities. The combination of some natural compounds (flavonoids, alkaloids, terpenes, isothiocyanates) with traditional AD treatments might be useful in improving the effectiveness of therapy, by reducing chronic inflammation and preventing flare-ups, and in promoting corticosteroid sparing. In addition, some of these nutraceuticals also appear to have a role in the treatment of psychological disorders, although the underlying oxidative stress mechanisms are different from those already known for AD.

Association of air quality index (AQI) with incidence of atopic dermatitis in Taiwan: A nationwide population-based cohort study

BACKGROUND

Air pollutants may aggravate atopic dermatitis (AD). However, the association between Air Quality Index (AQI) and incidence of AD remains unknown.

OBJECTIVE

To investigate association between AQI and incidence of AD, using the nationwide cohort in the Taiwan National Health Insurance Research Database (NHIRD).

METHODS

We included 21,278,938 participants from the NHIRD not diagnosed with AD before 2008. Long-term average AQI value, obtained from the Taiwan Air Quality Monitoring System Network, before AD diagnosis was calculated and linked for each participant.

RESULTS

199,205 incident cases of AD were identified from 2008 to 2018. Participants were classified into 4 quantiles (Q) by AQI value. With the lowest quantile, Q1, as reference, the AD risk increased significantly in the Q2 group (adjusted hazard ratio [aHR]: 1.29, 95% confidence interval [CI]: 1.04-1.65), Q3 group (aHR: 4.71, 95% CI: 3.78-6.04), and was highest in the Q4 group (aHR: 13.20, 95% CI: 10.86-16.60). As AQI treated as a continuous variable, an increase of 1 unit of AQI value added 7% of AD risk (aHR, 1.07, 95% CI: 1.07-1.08).

LIMITATIONS

The NHIRD lacks detailed information on individual subjects.

CONCLUSIONS

The results demonstrated a significant positive association between AQI and incidence of AD with a clear dose-response relationship.

Phenotypes, endotypes and genotypes of atopic dermatitis and allergy in populations of African ancestry on the continent and diaspora

Atopic dermatitis is a complex inflammatory condition characterized by synergist interactions between epidermal and immune related genotypes, skin barrier defects and immune dysregulation as well as microbial dysbiosis. Ethnicity-specific variations in clinical presentation, immune endotypes and genetic susceptibility have been described in diverse populations. We summarize available data with specific consideration of AD in populations of African ancestry. Some highlights include the observation of AD lesions on extensor surfaces, lichen planus-like AD, prurigo type AD and follicular AD in African populations. In addition, a consistent absence of dominant filaggrin gene defects has been reported. The detection of normal filaggrin protein content in AD skin implicates the contribution of alternative mechanisms in the pathogenesis of AD in African patients. Markedly high IgE has been described in paediatric and adult African AD. While Th2, Th22 and Th17 activation in African AD skin shares the same direction as with other populations, it has been noted that the magnitude of activation is dissimilar. Reduced Th17 cytokines have been observed in the circulation of moderate to severe paediatric AD.

Adipose tissue-derived exosomes alleviate particulate matter-induced inflammatory response and skin barrier damage in atopic dermatitis-like triple-cell model

Recently, particulate matter (PM) has been shown to exacerbate atopic dermatitis (AD) by inducing an inflammatory response. Meanwhile, several studies revealed that exosomes derived from adipose tissue-derived mesenchymal stem cells promote wound healing and alleviate inflammation via their regenerative and immunomodulatory capacities. Our study aimed to investigate the effects of human adipose tissue-derived mesenchymal stem cell-derived (ASC)-exosomes in PM-induced AD. An AD-like triple-cell model was established by treating human keratinocytes, dermal fibroblasts, and mast cells with polyinosinic:polycytidylic acid (Poly I:C) and interleukin 1 alpha (IL-1α). The effects of PM and ASC-exosomes on the expression of pro-inflammatory cytokines and skin barrier proteins were examined using quantitative real-time polymerase chain reaction, western blotting, and immunofluorescence. PM increased pro-inflammatory cytokines (IL-6, IL-1β, and IL-1α) and decreased the anti-inflammatory cytokine IL-10, while the mRNA expression of skin barrier proteins (loricrin and filaggrin) decreased. However, when the cells were treated with ASC-exosomes, the PM-induced effects on pro-inflammatory cytokines and skin barrier proteins were reversed. Our results confirmed that PM-induced inflammation and skin barrier damage were alleviated by ASC-exosomes in our AD-like triple-cell model. These data suggest that ASC-exosomes can serve as a therapeutic agent for PM-exacerbated AD.

Prenatal dietary exposure to mixtures of chemicals is associated with allergy or respiratory diseases in children in the ELFE nationwide cohort

INTRODUCTION

Prenatal exposure to environmental chemicals may be associated with allergies later in life. We aimed to examine the association between prenatal dietary exposure to mixtures of chemicals and allergic or respiratory diseases up to age 5.5 y.

METHODS

We included 11,638 mother-child pairs from the French "Étude Longitudinale Française depuis l'Enfance" (ELFE) cohort. Maternal dietary exposure during pregnancy to eight mixtures of chemicals was previously assessed. Allergic and respiratory diseases (eczema, food allergy, wheezing and asthma) were reported by parents between birth and age 5.5 years. Associations were evaluated with adjusted logistic regressions. Results are expressed as odds ratio (OR[95%CI]) for a variation of one SD increase in mixture pattern.

RESULTS

Maternal dietary exposure to a mixture composed mainly of trace elements, furans and polycyclic aromatic hydrocarbons (PAHs) was positively associated with the risk of eczema (1.10 [1.05; 1.15]), this association was consistent across sensitivity analyses. Dietary exposure to one mixture of pesticides was positively associated with the risk of food allergy (1.10 [1.02; 1.18]), whereas the exposure to another mixture of pesticides was positively but slightly related to the risk of wheezing (1.05 [1.01; 1.08]). This last association was not found in all sensitivity analyses. Dietary exposure to a mixture composed by perfluoroalkyl acids, PAHs and trace elements was negatively associated with the risk of asthma (0.89 [0.80; 0.99]), this association was consistent across sensitivity analyses, except the complete-case analysis.

CONCLUSION

Whereas few individual chemicals were related to the risk of allergic and respiratory diseases, some consistent associations were found between prenatal dietary exposure to some mixtures of chemicals and the risk of allergic or respiratory diseases. The positive association between trace elements, furans and PAHs and the risk of eczema, and that between pesticides mixtures and food allergy need to be confirmed in other studies. Conversely, the negative association between perfluoroalkyl acids, PAHs and trace elements and the risk of asthma need to be further explored.

Antioxidant defense of children and adolescents with atopic dermatitis: Association with disease severity

BACKGROUND

Atopic dermatitis (AD) is a relapsing, chronic cutaneous inflammatory disease with onset, in general, in early childhood. Chronic skin inflammation is associated with overproduction of reactive oxygen species (ROS) such as superoxide and hydrogen peroxide. Oxidative stress, an imbalance between the production of free radicals and antioxidant defense, results in tissue inflammation due to the upregulation of genes that encode inflammatory cytokines. This condition plays an important role in the pathogenesis of AD.

OBJECTIVE

To compare the antioxidant defense in children and adolescents with AD with that of healthy individuals and to verify the association of antioxidant defense with disease severity and nutritional status.

METHODS

Cross-sectional study that evaluated 48 children and adolescents with AD and 25 controls for nutritional assessment (body mass index z score [BMIZ] and height for age z score [HAZ]) and levels of vitamins A, C, E, and D, zinc (Zn), copper (Cu), antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPx]), high-sensitivity C-reactive protein (CRP) and interleukin 33 (IL-33).

RESULTS

There was no significant difference in the comparison between AD and control groups for serum levels of vitamins (A, D, C, and E), copper, and antioxidant enzymes. Serum zinc levels were higher in the AD group (β = 24.20; 95% CI 13.95-34.91; P < 0.001) even after adjusting the BMIZ, HAZ, gender, IL-33, and CRP. Children and adolescents with moderate or severe AD compared to mild AD (SCORAD - 36.7±17.4 vs 11.8 ± 3.9; P < 0.001) had lower values of the vitamin E/total lipid ratio (3.68 [0.29;12.63] vs 5.92 [3.27;17.37]; P = 0.013).

CONCLUSION

Children and adolescents with AD had higher concentrations OF elevated levels of zinc compared to controls, a fact not observed for other biomarkers of antioxidant defense. AD in moderate or severe forms presented lower concentrations of vitamin E, a potent antioxidant fat soluble.

Insights from the COCOA birth cohort: The origins of childhood allergic diseases and future perspectives

The ongoing COhort for Childhood Origin of Asthma and allergic diseases (COCOA) study is a prospective birth cohort investigating the origin and natural courses of childhood allergic diseases, including atopic dermatitis, food allergy, allergic rhinitis and asthma, with long-term prognosis. Initiated under the premise that allergic diseases result from a complex interplay of immune development alterations, environmental exposures, and host susceptibility, the COCOA study explores these dynamic interactions during prenatal and postnatal periods, framed within the hygiene and microbial hypotheses alongside the developmental origins of health and disease (DOHaD) hypothesis. The scope of the COCOA study extends to genetic predispositions, indoor and outdoor environmental variables affecting mothers and their offsprings such as outdoor and indoor air pollution, psychological factors, diets, and the microbiomes of skin, gut, and airway. We have embarked on in-depth investigations of diverse risk factors and the pathophysiological underpinnings of allergic diseases. By employing multi-omics approaches-proteomics, transcriptomics, and metabolomics-we gain deeper insights into the distinct pathophysiological processes across various endotypes of childhood allergic diseases, incorporating the exposome using extensive resources within the COCOA study. Integration with large-scale datasets, such as national health insurance records, enhances robustness and mitigates potential limitations inherent to birth cohort studies. As part of global networks focused on childhood allergic diseases, the COCOA study fosters collaborative research across multiple cohorts. The findings from the COCOA study are instrumental in informing precision medicine strategies for childhood allergic diseases, underpinning the establishment of disease trajectories.

Associations between long-term exposure to PM2.5 chemical constituents and allergic diseases: evidence from a large cohort study in China

BACKGROUND

Exposure to air pollutants may cause immune responses and further allergic diseases, but existing studies have mostly, if not all, focused on effects of short-term exposure to PM2.5 on allergic diseases.

OBJECTIVES

We estimated associations of long-term exposure to PM2.5 chemical constituents with allergic disease risks and effect modification.

METHODS

We used the baseline of a newly established, provincially representative cohort of 51,480 participants in southwest China. The presence of allergic rhinitis, allergic asthma, urticaria, and allergic conjunctivitis was self-reported by following a formed questionnaire in face-to-face interviews. The average concentrations of PM2.5 chemical constituents (NO3-, SO42-, NH4+, organic matter [OM], and black carbon [BC]) over participants' residence were estimated using machine learning models. Logistic regression with double robust estimator and weighted quantile sum regression were used to estimate the effects of PM2.5 chemical constituents on allergic disease risks, as well as relative importance of each PM2.5 chemical constituent.

RESULTS

Per interquartile range increase in the concentration of all PM2.5 chemical constituents was associated with the elevated risks for allergic asthma (OR = 1.79 [1.41-2.26]), allergic conjunctivitis (1.54 [1.19-2.00]), urticaria (1.36 [1.25-1.48]), and allergic rhinitis (1.18 [1.11-1.26]). NO3- contributed more to risks for allergic asthma (weight = 46.05 %), urticaria (72.29 %), and allergic conjunctivitis (47.65 %), while NH4+ contributed more to allergic rhinitis (78.07 %). OM contributed most to the risks for allergic asthma (30.81 %) and allergic conjunctivitis (31.40 %). BC was also associated with allergic rhinitis, urticaria, and allergic conjunctivitis, only with a considerable weight for urticaria (24.59 %). Joint effects of PM2.5 chemical constituents on risks for allergic rhinitis and urticaria were stronger in minorities and farmers than their counterparts.

CONCLUSION

Long-term exposure to PM2.5 chemical constituents was associated with the increased allergic disease risks, with NO3- and NH4+ accounting for the largest variance of the associations. Our findings would serve as scientific evidence for developing more explicit strategies of air pollution control.

RNA N6-methyladenosine methylation and skin diseases

Skin diseases are global health issues caused by multiple pathogenic factors, in which epigenetics plays an invaluable role. Post-transcriptional RNA modifications are important epigenetic mechanism that regulate gene expression at the genome-wide level. N6-methyladenosine (m6A) is the most prevalent modification that occurs in the messenger RNAs (mRNA) of most eukaryotes, which is installed by methyltransferases called "writers", removed by demethylases called "erasers", and recognised by RNA-binding proteins called "readers". To date, m6A is emerging to play essential part in both physiological processes and pathological progression, including skin diseases. However, a systematic summary of m6A in skin disease has not yet been reported. This review starts by illustrating each m6A-related modifier specifically and their roles in RNA processing, and then focus on the existing research advances of m6A in immune homeostasis and skin diseases.

Indoor particulate matter induces epigenetic changes in companion atopic dogs

The prevalence of atopic dermatitis (AD) is increasing and environmental factors are receiving attention as contributing causes. Indoor air pollutants (IAPs), especially particulate matter (PM) can alter epigenetic markers, DNA methylation (DNAm). Although DNAm-mediated epigenetic changes have been reported to modulate the pathogenesis of AD, their role at high risk of exposure to PM is still unclear. The study investigated the effects of exposure to IAPs in the development of AD and epigenetic changes through DNAm in companion atopic dogs that share indoor environment with their owners. Dogs were divided into two groups: AD (n = 47) and controls (n = 21). The IAPs concentration in each household was measured for 48 h, and a questionnaire on the residential environment was completed in all dogs. Eighteen dogs with AD and 12 healthy dogs were selected for DNAm analysis. In addition, clinical and immunological evaluations were conducted. The concentrations of PM2.5, PM10, and volatile organic compounds (VOCs) were significantly higher in the AD group. Moreover, there were more significant methylation differences in the LDLRAD4, KHSRP, and CTDSP2 genes in connection with PM10 in AD group compared to the controls. The degree of methylation of the LDLRAD4 and CTDSP2 genes was also correlated with related protein productions. The present study revealed that exposure to high indoor PM can cause epigenetic development of AD by methylation of the LDLRAD4, KHSRP, and CTDSP2 genes in dogs. Under the concept of "One Health," improving indoor environments should be considered to prevent the development of AD.

Early-immune development in asthma: A review of the literature

This review presents a comprehensive examination of the various factors contributing to the immunopathogenesis of asthma from the prenatal to preschool period. We focus on the contributions of genetic and environmental components as well as the role of the nasal and gut microbiome on immune development. Predisposing genetic factors, including inherited genes associated with increased susceptibility to asthma, are discussed alongside environmental factors such as respiratory viruses and pollutant exposure, which can trigger or exacerbate asthma symptoms. Furthermore, the intricate interplay between the nasal and gut microbiome and the immune system is explored, emphasizing their influence on allergic immune development and response to environmental stimuli. This body of literature underscores the necessity of a comprehensive approach to comprehend and manage asthma, as it emphasizes the interactions of multiple factors in immune development and disease progression.

Atopic Dermatitis Across Shades of Skin

Atopic dermatitis (AD) is a chronic, heterogeneous inflammatory skin disease that is associated with immense patient burden globally. There is increasing appreciation of disparities among patients identified as having skin of color (SOC), which often refers to patients of non-White race or non-European ancestry, but can broadly include individuals from a number of different racial, ethnic, ancestral, and skin pigmentation groups based on definition. In this narrative review, we discuss key terminology as it relates to AD across shades of skin, including modern definitions of 'race', 'ethnicity', and 'SOC'. We then synthesize the current literature describing disparities in AD prevalence, disease recognition, and burden alongside current data regarding genetic and immunologic findings across SOC populations. In the context of these findings, we highlight key concomitant social determinants of health, including environmental factors, socioeconomic status, and access to care, for which race often serves as a proxy for true biological and genetic differences. Finally, we discuss future efforts to shift to a more inclusive understanding of AD to encompass all shades of skin, to ensure equitable representation of diverse populations in high impact research, and intensify efforts to address the critical upstream factors driving observed disparities.

Racial and Ethnic Differences in Sociodemographic, Clinical, and Treatment Characteristics Among Patients with Atopic Dermatitis in the United States and Canada: Real-World Data from the CorEvitas Atopic Dermatitis Registry

INTRODUCTION

This real-world, cross-sectional study compared sociodemographic, clinical and treatment characteristics, and patient-reported outcomes (PROs) among racial/ethnic groups in patients with atopic dermatitis (AD) who are candidates for systemic therapy.

METHODS

This study included adults with dermatologist- or dermatology practitioner-diagnosed AD enrolled in the CorEvitas AD Registry (July 2020-July 2021). All patients initiated systemic therapy within 12 months prior to or at enrollment or had moderate-to-severe AD (vIGA-AD® ≥ 3 and Eczema Area and Severity Index [EASI] ≥ 12) at enrollment. Patients were categorized into five mutually exclusive racial/ethnic groups: non-Hispanic White, Black, Asian, Other/Multiracial, and Hispanic (any race). Patient, clinical, and treatment characteristics were captured at enrollment. Differences in means or proportions of characteristics among racial/ethnic groups were descriptively summarized using effect sizes. Adjusted prevalence ratios and mean differences were estimated (White race/ethnicity group as the reference category) with 95% confidence intervals (CI).

RESULTS

Among 1288 patients, 64% (n = 822) were White, 13% (n = 167) Black, 10% (n = 129) Asian, 8% (n = 97) Hispanic, and 6% (n = 73) Other/Multiracial. In adjusted analyses, statistically more severe EASI lichenification was noted among Black compared with White patients at the head and neck (mean difference, 0.21, [95% CI 0.06, 0.36]; p = 0.01), trunk (0.32, [0.17, 0.47]; p < 0.001), upper extremities (0.27, [0.09, 0.44]; p = 0.008), and lower extremities (0.39, [0.21, 0.57]; p < 0.001). Statistically more severe EASI lichenification was observed among Asian vs White patients in certain areas (mean difference, head and neck, 0.22 [0.04, 0.39], p = 0.01; trunk, 0.25 [0.07, 0.43], p < 0.001; lower extremities, 0.22 [0.01, 0.43], p < 0.001) and SCORing for AD lichenification (mean difference: 0.34 [0.15, 0.52]; p < 0.001). Significantly higher mean pruritus over the past 7 days for Black (mean difference: 0.63 [0.01, 1.26] and Hispanic patients (0.60 [0.11, 1.09]; p = 0.03) vs White patients was observed. Among AD clinical features, the prevalence of facial erythema was significantly lower among Black compared with White patients (prevalence ratio = 0.38, [0.22, 0.67]; p = 0.007).

CONCLUSION

Racial/ethnic differences exist in sociodemographic, clinical and treatment characteristics, disease severity, and PROs among real-world AD patients who are candidates for systemic therapy. Recognizing these variations may be of critical importance for dermatologists for the design and delivery of targeted/personalized medicine approaches.

The immunological and structural epidermal barrier dysfunction and skin microbiome in atopic dermatitis-an update

Atopic dermatitis (AD) is a common, chronic and relapsing inflammatory skin disease with various clinical presentations and combinations of symptoms. The pathophysiology of AD is complex and multifactorial. There are several factors involved in the etiopathogenesis of AD including structural and immunological epidermal barrier defect, imbalance of the skin microbiome, genetic background and environmental factors. Alterations in structural proteins, lipids, proteases, and their inhibitors, lead to the impairment of the stratum corneum which is associated with the increased skin penetration and transepidermal water loss. The elevated serum immunoglobulin E levels and blood eosinophilia have been shown in the majority of AD patients. Type 2 T-helper cell immune pathway with increased expression of interleukin (IL)-4, IL-5, and IL-13, has an important role in the etiopathogenesis of AD. Both T cells and keratinocytes contribute to epidermal barrier impairment in AD via a dynamic interaction of cytokines and chemokines. The skin microbiome is another factor of relevance in the etiopathogenesis of AD. It has been shown that during AD flares, Staphylococcus aureus (S. aureus) colonization increased, while Staphylococcus epidermidis (S. epidermidis) decreased. On the contrary, S. epidermidis and species of Streptococcus, Corynebacterium and Propionibacterium increased during the remision phases. However, it is not clear whether skin dysbiosis is one of the symptoms or one of the causes of AD. There are several therapeutic options, targeting these pathways which play a critical role in the etiopathogenesis of AD. Although topical steroids are the mainstay of the treatment of AD, new biological therapies including IL-4, IL-13, and IL-31 inhibitors, as well as Janus kinase inhibitors (JAKi), increasingly gain more importance with new advances in the therapy of AD. In this review, we summarize the role of immunological and structural epidermal barrier dysfunction, immune abnormalities, impairment of lipids, filaggrin mutation and skin microbiome in the etiopathogenesis of AD, as well as the therapeutic options for AD and their effects on these abnormalities in AD skin.

Regulatory T Cell-Targeted Immunomodulatory Therapy for Long-Term Clinical Improvement of Atopic Dermatitis: Hypotheses and Perspectives

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disorder characterized by itching and eczematous lesions. It is often associated with a personal or familial history of allergic diseases. Allergic inflammation induced by immunoglobulin E and T-helper type 2 (Th2) cell responses to common environmental agents has been suggested to play an essential role in AD pathogenesis. The standard therapies for AD, including topical or systemic agents, focus on controlling skin inflammation. Recently developed monoclonal antibody to interleukin-4 receptor alpha or Janus kinase inhibitors can provide significant clinical improvements in patients with AD by inhibiting Th2 cell-mediated skin inflammation. However, the clinical efficacy of the Th2 cell-targeted therapy is transient and incomplete in patients with AD. Patients with AD are seeking a permanent cure. Therefore, the development of novel immunomodulatory strategies that can improve a long-term clinical outcome and provide a long-term treatment-free clinical remission of AD (disease-modifying therapy) is needed. Regulatory T (Treg) cells play a critical role in the maintenance of immune tolerance and suppress the development of autoimmune and allergic diseases. This review provides three working hypotheses and perspectives for the treatment of AD by Treg cell activation. (1) A decreased number or function of Treg cells is a critical event that causes the activation of Th2 cells, leading to the development and maintenance of AD. (2) Activation of Treg cells is an effective therapeutic approach for AD. (3) Many different immunomodulatory strategies activating Treg cells can provide a long-term clinical improvement of AD by induction of immune tolerance. The Treg cell-targeted immunomodulatory therapies for AD include allergen immunotherapy, microbiota, vitamin D, polyvalent human immunoglobulin G, monoclonal antibodies to the surface antigens of T cell or antigen-presenting cell, and adoptive transfer of autologous Treg cells or genetically engineered Treg cells expanded in vitro.

The Impact of Air Pollution on Atopic Dermatitis

PURPOSE OF REVIEW

Atopic dermatitis (AD) remains a dermatological disease that imposes a significant burden on society. Air pollution has previously been linked to both the onset and severity of atopic dermatitis. As air pollution remains a critical environmental factor impacting human health, this review seeks to provide an overview of the relationship between different air pollutants and AD.

RECENT FINDINGS

AD can develop from multiple causes that can be broadly grouped into epidermal barrier dysfunction and immune dysregulation. Air pollution imposes significant health risks and includes a wide variety of pollutant types. AD has been linked to outdoor air pollutants such as particulate matter (PM), volatile organic compounds (VOC), gaseous compounds, and heavy metals. Exposure to indoor pollutants such as tobacco smoke and fungal molds has also been associated with an increased incidence of AD. While different pollutants impact distinct molecular pathways in the cell, they mostly converge on ROS product, DNA damage, and dysregulated T-cell activity and cytokine production. The presented review suggests a strengthening tie between air pollution and AD. It points to opportunities for further studies to clarify, as well as potential therapeutic opportunities that leverage the mechanistic relationships between air pollution and AD.

Protocatechuic Acid and Syringin from Saussurea neoserrata Nakai Attenuate Prostaglandin Production in Human Keratinocytes Exposed to Airborne Particulate Matter

Saussurea neoserrata Nakai offers a reliable and efficient source of antioxidants that can help alleviate adverse skin reactions triggered by air pollutants. Air pollutants, such as particulate matter (PM), have the ability to infiltrate the skin and contribute to the higher occurrence of cardiovascular, cerebrovascular, and respiratory ailments. Individuals with compromised skin barriers are particularly susceptible to the impact of PM since it can be absorbed more readily through the skin. This study investigated the impact of protocatechuic acid and syringin, obtained from the n-BuOH extract of S. neoserrata Nakai, on the release of PGE₂ and PGD₂ induced by PM₁₀. Additionally, it examined the gene expression of the synthesis of PGE₂ and PGD₂ in human keratinocytes. The findings of this research highlight the potential of utilizing safe and efficient plant-derived antioxidants in dermatological and cosmetic applications to mitigate the negative skin reactions caused by exposure to air pollution.

Climate Change, Skin Health, and Dermatologic Disease: A Guide for the Dermatologist

Climate change has a pervasive impact on health and is of clinical relevance to every organ system. Climate change-related factors impact the skin's capacity to maintain homeostasis, leading to a variety of cutaneous diseases. Stratospheric ozone depletion has led to increased risk of melanoma and keratinocyte carcinomas due to ultraviolet radiation exposure. Atopic dermatitis, psoriasis, pemphigus, acne vulgaris, melasma, and photoaging are all associated with rising levels of air pollution. Elevated temperatures due to global warming induce disruption of the skin microbiome, thereby impacting atopic dermatitis, acne vulgaris, and psoriasis, and high temperatures are associated with exacerbation of skin disease and increased risk of heat stroke. Extreme weather events due to climate change, including floods and wildfires, are of relevance to the dermatologist as these events are implicated in cutaneous injuries, skin infections, and acute worsening of inflammatory skin disorders. The health consequences as well as the economic and social burden of climate change fall most heavily on vulnerable and marginalized populations due to structural disparities. As dermatologists, understanding the interaction of climate change and skin health is essential to appropriately manage dermatologic disease and advocate for our patients.

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.

Factors Associated with Atopic Dermatitis among Children Aged 6 to 14 Years in Alimosho Local Government, Lagos, Nigeria

There has been a rise in the prevalence of atopic dermatitis (AD) globally, especially in low-and middle-income countries such as Nigeria. The condition has been linked to genetic predisposes, living conditions, and environmental factors. Environmental factors are considered a significant contributor to AD in low- and middle-income countries. This study determined the prevalence of AD in south-western Nigeria and identified risk factors in home and school environments that children aged 6 to 14 years are exposed to. A cross-sectional study was adopted, and the total sample size was 349. Four randomly selected health facilities were used for the study. A questionnaire was used to determine the risk factors in the population. Data analysis was performed using the latest version of Statistical Package for Social Science (SPSS). The prevalence of atopic dermatitis in this study is 25%. Atopic dermatitis was found to be common in females (27%). According to the univariate analysis, children who lived where trucks pass on the street almost daily had the highest cases of atopic dermatitis (28%). Children with rugs in their houses (26%) and those whose houses are surrounded by bushes (26%) had higher cases of atopic dermatitis. Children who played on school grass (26%), attended creche with rubber toys (28%), and attended school where wooden chairs (28%) and chalkboards (27%) are used had a higher number of AD. Bivariate analysis showed an association between AD with a mother's monthly income (p = 0.012) and eating potatoes (p = 0.005), fruits (p = 0.040), and cereal (p = 0.057). In the multivariate analysis, the consumption of fruits (p = 0.02), potatoes (p < 0.001), and cereal (p = 0.04) were identified as risk factors associated with AD. It is envisaged that the study will serve as a basis for possible research on evidence-based and primary prevention options. Hence, we recommend health education activities to empower communities to protect themselves against environmental risk factors that are preventable.

Protective Effects of a Jellyfish-Derived Thioredoxin Fused with Cell-Penetrating Peptide TAT-PTD on H2O2-Induced Oxidative Damage

Thioredoxin (Trx) plays a critical role in maintaining redox balance in various cells and exhibits anti-oxidative, anti-apoptotic, and anti-inflammatory effects. However, whether exogenous Trx can inhibit intracellular oxidative damage has not been investigated. In previous study, we have identified a novel Trx from the jellyfish Cyanea capillata, named CcTrx1, and confirmed its antioxidant activities in vitro. Here, we obtained a recombinant protein, PTD-CcTrx1, which is a fusion of CcTrx1 and protein transduction domain (PTD) of HIV TAT protein. The transmembrane ability and antioxidant activities of PTD-CcTrx1, and its protective effects against H₂O₂-induced oxidative damage in HaCaT cells were also detected. Our results revealed that PTD-CcTrx1 exhibited specific transmembrane ability and antioxidant activities, and it could significantly attenuate the intracellular oxidative stress, inhibit H₂O₂-induced apoptosis, and protect HaCaT cells from oxidative damage. The present study provides critical evidence for application of PTD-CcTrx1 as a novel antioxidant to treat skin oxidative damage in the future.

Preventive Effect of Pharmaceutical Phytochemicals Targeting the Src Family of Protein Tyrosine Kinases and Aryl Hydrocarbon Receptor on Environmental Stress-Induced Skin Disease

The skin protects our body; however, it is directly exposed to the environment and is stimulated by various external factors. Among the various environmental factors that can threaten skin health, the effects of ultraviolet (UV) and particulate matter (PM) are considered the most notable. Repetitive exposure to ultraviolet and particulate matter can cause chronic skin diseases such as skin inflammation, photoaging, and skin cancer. The abnormal activation of the Src family of protein tyrosine kinases (SFKs) and the aryl hydrocarbon receptor (AhR) in response to UV and/or PM exposure are involved in the development and aggravation of skin diseases. Phytochemicals, chemical compounds of natural plants, exert preventive effects on skin diseases through the regulation of various signaling pathways. Therefore, this review aims to highlight the efficacy of phytochemicals as potential nutraceuticals and pharmaceutical materials for the treatment of skin diseases, primarily by targeting SFK and AhR, and to explore the underlying mechanisms of action. Future studies are essential to validate the clinical potential for the prevention and treatment of skin diseases.

The impact of airborne ultrafine particulate matter on human keratinocyte stem cells

OBJECTIVE

Air pollution is today fully acknowledged to be a significant public health problem. Rapid urbanization exposed us to a variety of unhealthy ambient air pollutants at high concentrations. The emergence of airborne ultrafine particles has added an additional dimension to this already complex problem of air pollution. The skin has different functions, one of them being the protection against the deleterious effect of external agents. The aim of this study is to evaluate the impact of airborne ultrafine particles (UFP) pollution on skin aging and on keratinocyte differentiation.

METHODS

Ex vivo human skin biopsies and cultured keratinocytes stem cells (KSC) were submitted to diesel exhaust-derived UFP. Reactive oxygen species (ROS) production was assessed with the MitoSOX™ probe. Keratinocyte stemness potential was evaluated by the immunodetection of keratin 15 (K15) and p63 (∆N isoforms). Effect of UFP on the epithelial niche maintenance was evaluated by immunodetection of Sox9. Reconstructed epidermis model was used to assess the impact of UFP on keratinocyte differentiation and aging.

RESULTS

UFP exposure induced ROS production and disturbed K15, ∆Np63 and Sox9 expression in KSC or ex vivo skin. Finally, investigations on reconstructed epidermis revealed a phenotype marked by impaired keratinocyte differentiation.

CONCLUSION

These results indicate that UFP pollution is a potent extrinsic factor of skin aging, affecting the keratinocyte stem cell potential and the skin renewal process.

Air Pollution and Atopic Dermatitis, from Molecular Mechanisms to Population-Level Evidence: A Review

Atopic dermatitis (AD) has increased in prevalence to become the most common inflammatory skin condition globally, and geographic variation and migration studies suggest an important role for environmental triggers. Air pollution, especially due to industrialization and wildfires, may contribute to the development and exacerbation of AD. We provide a comprehensive, multidisciplinary review of existing molecular and epidemiologic studies on the associations of air pollutants and AD symptoms, prevalence, incidence, severity, and clinic visits. Cell and animal studies demonstrated that air pollutants contribute to AD symptoms and disease by activating the aryl hydrocarbon receptor pathway, promoting oxidative stress, initiating a proinflammatory response, and disrupting the skin barrier function. Epidemiologic studies overall report that air pollution is associated with AD among both children and adults, though the results are not consistent among cross-sectional studies. Studies on healthcare use for AD found positive correlations between medical visits for AD and air pollutants. As the air quality worsens in many areas globally, it is important to recognize how this can increase the risk for AD, to be aware of the increased demand for AD-related medical care, and to understand how to counsel patients regarding their skin health. Further research is needed to develop treatments that prevent or mitigate air pollution-related AD symptoms.

Protective effects of dietary grape against atopic dermatitis-like skin lesions in NC/NgaTndCrlj mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease with significant health/economic burdens. Existing therapies are not fully effective, necessitating development of new approaches for AD management. Here, we report that dietary grape powder (GP) mitigates AD-like symptoms in 2,4-dinitrofluorobenzene (DNFB)-induced AD in NC/NgaTndCrlj mice. Using prevention and intervention protocols, we tested the efficacy of 3% and 5% GP-fortified diet in a 13-weeks study. We found that GP feeding markedly inhibited development and progression of AD-like skin lesions, and caused reduction in i) epidermal thickness, mast cell infiltration, ulceration, excoriation and acanthosis in dorsal skin, ii) spleen weight, extramedullary hematopoiesis and lymph nodes sizes, and iii) ear weight and IgE levels. We also found significant modulations in 15 AD-associated serum cytokines/chemokines. Next, using quantitative global proteomics, we identified 714 proteins. Of these, 68 (normal control) and 21 (5% GP-prevention) were significantly modulated (≥2-fold) vs AD control (DNFB-treated) group, with many GP-modulated proteins reverting to normal levels. Ingenuity pathway analysis of GP-modulated proteins followed by validation using ProteinSimple identified changes in acute phase response signaling (FGA, FGB, FGG, HP, HPX, LRG1). Overall, GP supplementation inhibited DNFB-induced AD in NC/NgaTndCrlj mice in both prevention and intervention trials, and should be explored further.

Exposure to isocyanates predicts atopic dermatitis prevalence and disrupts therapeutic pathways in commensal bacteria

Atopic dermatitis (AD) is a chronic inflammatory skin condition increasing in industrial nations at a pace that suggests environmental drivers. We hypothesize that the dysbiosis associated with AD may signal microbial adaptations to modern pollutants. Having previously modeled the benefits of health-associated Roseomonas mucosa, we now show that R. mucosa fixes nitrogen in the production of protective glycerolipids and their ceramide by-products. Screening EPA databases against the clinical visit rates identified diisocyanates as the strongest predictor of AD. Diisocyanates disrupted the production of beneficial lipids and therapeutic modeling for isolates of R. mucosa as well as commensal Staphylococcus. Last, while topical R. mucosa failed to meet commercial end points in a placebo-controlled trial, the subgroup who completed the full protocol demonstrated sustained, clinically modest, but statistically significant clinical improvements that differed by study site diisocyanate levels. Therefore, diisocyanates show temporospatial and epidemiological association with AD while also inducing eczematous dysbiosis.

Exposure to air pollution and incidence of atopic dermatitis in the general population: A national population-based retrospective cohort study

BACKGROUND

To date, little evidence is available to determine whether atopic dermatitis (AD) can be caused by exposure to air pollutants, including gases and particulate matter.

OBJECTIVE

We aimed to evaluate the relationship between air pollutants and incidence of AD using the National Health Insurance Service-National Sample Cohort database.

METHODS

We included 209,168 subjects from the general population previously not diagnosed with AD between 2008 and 2013. Long-term average concentration of air pollutants before diagnosis was calculated for each subject.

RESULTS

For 1,030,324 person-years, incident cases of AD were observed in 3203 subjects. There was a significant positive association between incidence of AD and long-term average concentration of particulate matter smaller than 2.5 μm in diameter (hazard ratio [HR], 1.420; 95% CI, 1.392-1.448; for 1 μg/m³), particulate matter smaller than 10 μm in diameter (HR, 1.333, 95% CI, 1.325-1.341; for 1 μg/m³), sulfur dioxide (HR, 1.626; 95% CI, 1.559-1.695; for 1 parts per billion), nitrogen dioxide (HR, 1.200; 95% CI, 1.187-1.212; for 1 parts per billion), and carbon monoxide (HR, 1.005; 95% CI, 1.004-1.005; for 1 parts per billion) after adjusting for age, sex, income, comorbid diseases, and meteorologic variables.

LIMITATIONS

The National Health Insurance Service database lacks detailed information on individual subjects.

CONCLUSIONS

This study demonstrated that long-term exposure to air pollutants, including gases and particulate matter, is an independent risk factor for developing AD.

Air Pollution: Possible Interaction between the Immune and Nervous System?

Exposure to environmental pollutants is a serious and common public health concern associated with growing morbidity and mortality worldwide, as well as economic burden. In recent years, the toxic effects associated with air pollution have been intensively studied, with a particular focus on the lung and cardiovascular system, mainly associated with particulate matter exposure. However, epidemiological and mechanistic studies suggest that air pollution can also influence skin integrity and may have a significant adverse impact on the immune and nervous system. Air pollution exposure already starts in utero before birth, potentially causing delayed chronic diseases arising later in life. There are, indeed, time windows during the life of individuals who are more susceptible to air pollution exposure, which may result in more severe outcomes. In this review paper, we provide an overview of findings that have established the effects of air pollutants on the immune and nervous system, and speculate on the possible interaction between them, based on mechanistic data.

Anti-Pollution Activity, Antioxidant and Anti-Inflammatory Effects of Fermented Extract from Smilax china Leaf in Macrophages and Keratinocytes

Air pollution has considerable effects on the human skin, showing that every single pollutant has a different toxicological impact on it. The oxidative stress that exceeds the skin’s antioxidant capacity can lead to oxidative damage and premature skin aging by repeated air pollutant contact. In this study, according to the generalized protocol available to objectively substantiate the ‘anti-pollution’ claim, we evaluated several biomarkers after pollutants exposure in Raw 264.7 macro-phages and HaCaT keratinocytes to investigate the possibility of anti-pollution cosmetic material of fermented extract from Smilax china leaves (FESCL). FESCL decreased pollutants-induced luciferase activity in a dose-dependent manner, and FESCL significantly inhibited XRE-luciferase activity at a concentration of 1%. The IC50 value of FESCL showed the same DPPH scavenging activity at 0.0625% as ascorbic acid, and the maximum DPPH scavenging activity (92.44%) at 1%. The maximum permissible non-cytotoxic concentrations of FESCL for a Raw 264.7 cell was determined to be 2%, where PGE2 production of FESCL was inhibited by 78.20%. These results show the anti-pollution activity of FESCL against the pollutant-stimulated human living skin explants. In conclusion, we confirmed the anti-pollution potential of FESCL as one of the functional materials in cosmetic formulation.

The association between domestic hard water and eczema in adults from the UK Biobank cohort study

BACKGROUND

Eczema is a chronic inflammatory skin disease. Domestic water with high mineral content (hard water) is a risk factor for eczema in children, but this association has not been assessed in adults.

OBJECTIVES

To examine the association between domestic hard water supply and eczema prevalence and incidence in adults aged 40-69 years and the contextual effect in eczema outcomes by postcode in adults in the UK.

METHODS

We used data from the UK Biobank study collected in 2006-10 (baseline) and 2013-14 (follow-up). Eczema prevalence at baseline (2006-10) and at follow-up (2013-14) and incidence (new onset between baseline and follow-up) were determined from the touchscreen questionnaires and nurse-led interviews. Domestic hard water information was obtained in 2005 and 2013 from the local water supply companies in England, Wales and Scotland as CaCO3 concentrations. We fitted multilevel logistic regression models with random intercepts for postcode areas to examine the effect of domestic hard water on eczema outcomes, and we measured components of variance.

RESULTS

In total, 306 531 participants with a mean age of 57 years nested across 7642 postcodes were included in the baseline analysis, and 31 036 participants nested across 3695 postcodes were included in the follow-up analysis. We observed an increase in the odds of eczema at baseline [odds ratio (OR) 1·02, 95% confidence interval (CI) 1·01-1·04] per 50 mg L-1 of CaCO3 increase. Furthermore, exposure to domestic hard water (> 200 mg L-1 of CaCO3 ) was associated with increased odds of prevalent eczema at baseline (OR 1·12, 95% CI 1·04-1·22). Moreover, there was a significant linear trend (P < 0·001) in which increasing levels of hard water increased eczema prevalence risk. No association was observed with incident eczema or eczema at follow-up. The intraclass correlation coefficient for postcode was 1·6% (95% CI 0·7-3·4), which remained unexplained by area-level socioeconomic measures.

CONCLUSIONS

Increasing levels of domestic hard water, as measured by CaCO3 concentrations, were associated with an increased prevalence of eczema in adults but not increased incidence. Ongoing efforts to reduce hard water exposure may have a beneficial effect in reducing the burden of eczema in adults. Further research is needed to explore area-level factors that may lead to eczema. What is already known about this topic? Hard water is formed when minerals are dissolved in water from filtration through sedimentary rocks. Several studies have reported a higher prevalence of eczema in areas with hard water. However, all studies on this topic have assessed this in infants and school-aged children, while this association has not been explored in adults. What does this study add? Our findings suggest that exposure to higher concentrations of domestic hard water is associated with an increase in eczema prevalence in adults aged 40-69 years. Ongoing efforts to reduce hard water exposure may have a beneficial effect in reducing eczema prevalence in adults.

Biomass Smoke Exposure and Atopy among Young Children in the Western Highlands of Guatemala: A Prospective Cohort Study

Women and children in rural regions of low-income countries are exposed to high levels of household air pollution (HAP) as they traditionally tend to household chores such as cooking with biomass fuels. Early life exposure to air pollution is associated with aeroallergen sensitization and developing allergic diseases at older ages. This prospective cohort study assigned HAP-reducing chimney stoves to 557 households in rural Guatemala at different ages of the study children. The children's air pollution exposure was measured using personal CO diffusion tubes. Allergic outcomes at 4-5 years old were assessed using skin prick tests and International Study of Asthma and Allergies in Childhood (ISAAC)-based questionnaires. Children assigned to improved stoves before 6 months old had the lowest HAP exposure compared to the other groups. Longer exposure to the unimproved stoves was associated with higher risks of maternal-reported allergic asthma (OR = 2.42, 95% CI: 1.11-5.48) and rhinitis symptoms (OR = 2.01, 95% CI: 1.13-3.58). No significant association was found for sensitization to common allergens such as dust mites and cockroaches based on skin prick tests. Reducing HAP by improving biomass burning conditions might be beneficial in preventing allergic diseases among children in rural low-income populations.

Relationship between air pollution and childhood atopic dermatitis in Chongqing, China: A time-series analysis

Background

The prevalence of atopic dermatitis (AD) in children has increased substantially in China over past decades. The ongoing rise in the prevalence stresses the important role of the environmental factors in the pathogenesis of AD. However, studies evaluating the effects of air pollution on AD in children are scarce.

Objective

To quantitatively assess the association between air pollution and outpatient visits for AD in children.

Methods

In this time-series study, we collected 214,747 children of AD from January 1, 2015 to December 31, 2019 through the electronic data base in the Children's Hospital of Chongqing Medical University. The number of daily visits was treated as the dependent variable, and generalized additive models with a Poisson like distribution were constructed, controlling for relevant potential confounders and performing subgroup analyses.

Results

Each 10 μg/m³ increase in PM_2.5, PM₁₀, SO₂, NO₂ and each 1 mg/m³ increase in CO concentrations was significantly associated with a 0.7% (95% CI: 0.2, 1.3%), 0.9% (95% CI: 0.5, 1.4%), 11% (95% CI: 7.5, 14.7%), 5.5% (95% CI: 4.3, 6.7%) and 10.1% (95% CI: 2.7, 18.2%) increase of AD outpatient visits on the current day, respectively. The lag effect was found in SO₂, PM₁₀, and NO_2. The effects were stronger in cool season and age 0-3 group.

Conclusions

Our study suggests that short-term exposure to ambient air pollution contributes to more childhood AD outpatient visits in Chongqing, China.

A simple device for simulating skin adsorption of polycyclic aromatic hydrocarbons: design and application

Dermal exposure is one of the main ways of human body exposure to atmospheric contaminants such as polycyclic aromatic hydrocarbons (PAHs). The skin type significantly affects the skin adsorption of contaminants. However, this is commonly ignored in assessing the dermal exposure based on the atmospheric concentrations of contaminants. In this study, a simulation device suitable for human dermal pollutant exposure assessment was established, which used polyethylene balloons coated with different doses of glycerol trioleate to simulate oily skin, neutral skin, and dry skin type. The sampling effectiveness of the device was verified, and the device was applied to the skin exposure assessment of atmospheric PAHs at different scenarios. Kinetic experiments indicated a linear adsorption within 6 h. The adsorption kinetic constants (k) of PAHs on the oily surface of the balloon were significantly higher than those on the dry surface, especially for PAHs with high ring numbers. Compared with the calculated skin adsorption based on atmospheric concentrations, the results of this simulation device can better simulate the skin adsorption of atmospheric contaminants on different skin types and in different scenarios. Based on the result of balloon sampling, the dermal exposure of PAH_{3 rings} by oily skin inside the tunnel is up to 5.668 ng/cm²/day, indicating a non-negligible health risk.

The influence of personal care products on ozone-skin surface chemistry

Personal care products are increasingly being marketed to protect skin from the potentially harmful effects of air pollution. Here, we experimentally measure ozone deposition rates to skin and the generation rates and yields of oxidized products from bare skin and skin coated with various lotion formulations. Lotions reduced the ozone flux to the skin surface by 12% to 25%; this may be due to dilution of reactive skin lipids with inert lotion compounds or by reducing ozone diffusivity within the resulting mixture. The yields of volatile squalene oxidation products were 25% to 70% lower for a commercial sunscreen and for a base lotion with an added polymer or with antioxidants. Lower yields are likely due to competitive reactions of ozone with lotion ingredients including some ingredients that are not intended to be ozone sinks. The dynamics of the emissions of squalene ozonation product 6 methyl-2-heptenone (6MHO) suggest that lotions can dramatically reduce the solubility of products in the skin film. While some lotions appear to reduce the rate of oxidation of squalene by ozone, this evidence does not yet demonstrate that the lotions reduce the impact of air pollution on skin health.

An Overview of the Latest Metabolomics Studies on Atopic Eczema with New Directions for Study

Atopic eczema (AE) is an inflammatory skin disorder affecting approximately 20% of children worldwide and early onset can lead to asthma and allergies. Currently, the mechanisms of the disease are not fully understood. Metabolomics, the analysis of small molecules in the skin produced by the host and microbes, opens a window to observe the mechanisms of the disease which then may lead to new drug targets for AE treatment. Here, we review the latest advances in AE metabolomics, highlighting both the lipid and non-lipid molecules, along with reviewing the metabolites currently known to reside in the skin.

Differences in Occurrence, Risk Factors and Severity of Early-onset Atopic Dermatitis among Preterm and Term Children

This prospective birth cohort followed 150 preterm and 300 term newborns during the first year of life to assess possible differences in risk factors, age at onset, anatomical location, and severity of atopic dermatitis. Atopic dermatitis was diagnosed clinically, and severity was assessed using Eczema Area Severity Index (EASI). DNA was analysed for filaggrin gene mutations. Parents were asked about environmental exposures and emollient use. Atopic dermatitis during the first year of life was observed in 21.2% of children and was more common in term children compared with preterm children (26.7% vs 11.7%, p < 0.001), with lower age of onset (4 vs 6 months, p < 0.05) and more severe disease at onset (EASI: 4.8 vs 0.4, p < 0.0005). Environmental risk factors for atopic dermatitis were essentially similar for preterm and term born children, apart from winter and autumn births. Filaggrin gene mutations were less common in preterm than term children (4.1% vs 9.2%, p = 0.06).

Atopic dermatitis endotypes: knowledge for personalized medicine

PURPOSE OF REVIEW

Endotypes are clinically relevant phenotypes that can be explained by molecular mechanisms, and are defined to predict the development, progression, prognosis and responses to treatment on the individual level. This review summarizes atopic dermatitis phenotypes, endotypes and their potential application for personalized medicine.

RECENT FINDINGS

Atopic dermatitis can be classified into several phenotypes according to disease courses that likely have common pathophysiology. The genotype is important to define endotypes, but the value of genotype alone remains somewhat limited in most atopic dermatitis patients. Recent studies have demonstrated that atopic dermatitis phenotypes according to ethnicity or age can be classified into endotypes based on the dominant immunologic markers, that is TH1/TH2/TH17/TH22 cells. Newly developed biologic agents targeting specific cytokines show therapeutic potential in a personalized medicine approach.

SUMMARY

Cytokine-based endotypes in different age groups or ethnic groups have contributed to expanding our understanding of atopic dermatitis. Recent biologics or small molecules can be used for more personalized treatment of atopic dermatitis. Further research using integrated multiomic analysis is needed to define a more detailed classification of endotypes and provide endotype-driven targeted therapies for personalized medicine.

Skin Care Product Rich in Antioxidants and Anti-Inflammatory Natural Compounds Reduces Itching and Inflammation in the Skin of Atopic Dermatitis Patients

The atopic dermatitis (AD) complex pathogenesis mechanism reveals marked changes of certain signaling factors as well as some morphological alterations in the epidermis. Reduced resilience against environmental factors and oxidative stress often makes the treatment with corticosteroids or tacrolismus ointments indispensable. In view of the correlation between oxidative stress and AD pathological factors, antioxidants can be incorporated into AD management strategies. This study investigates a curly kale, apple and green tea-containing natural extract rich in antioxidants for its effects on signaling inflammatory molecules and skin barrier enhancement in human epidermal keratinocytes- (NHEKs) based cell assays. Furthermore, the skin penetration on porcine ears was measured ex vivo using Raman micro spectroscopy. Finally, in a double-blind half-side, placebo-controlled clinical study, the effects of a formulation containing this extract were analyzed for the influence of lesion severity, epidermal barrier function, and pruritus in mild to moderately AD patients. Summarizing our results: The extract reduces expression of inflammatory cytokines in keratinocytes and increases barrier-related molecules. The verum formulation with a very high antioxidant capacity used in AD patients with mild to moderate lesions reduces itching, local SCORAD, and improves barrier function and the hydration of skin lesions.

Residential greenness, asthma, and lung function among children at high risk of allergic sensitization: a prospective cohort study

BACKGROUND

While benefits of greenness to health have been reported, findings specific to child respiratory health are inconsistent.

METHODS

We utilized a prospective birth cohort followed from birth to age 7 years (n = 617). Residential surrounding greenness was quantified via Normalized Difference Vegetation Index (NDVI) within 200, 400, and 800 m distances from geocoded home addresses at birth, age 7 years, and across childhood. Respiratory health outcomes were assessed at age 7 years, including asthma and lung function [percent predicted forced expiratory volume in the first second (%FEV₁), percent predicted forced vital capacity (%FVC), and percent predicted ratio of forced expiratory volume in the first second to forced vital capacity (%FEV₁/FVC)]. We assessed associations using linear and logistic regression models adjusted for community deprivation, household income, and traffic-related air pollution. We tested for effect measure modification by atopic status.

RESULTS

We noted evidence of positive confounding as inverse associations were attenuated upon adjustment in the multivariable models. We found evidence of effect measure modification of NDVI and asthma within 400 m at age 7 years by atopic status (p = 0.04), whereby children sensitized to common allergens were more likely to develop asthma as exposure to greenness increased (OR = 1.3, 95% CI: 0.9, 2.0) versus children not sensitized to common allergens (OR = 0.8, 95% CI: 0.5, 1.2). We found consistently positive associations between NDVI and %FEV₁ and %FVC which similarly evidenced positive confounding upon adjustment. In the adjusted regression models, NDVI at 7 years of age was associated with %FEV₁ (200 m: β = 2.1, 95% CI: 0.1, 3.3; 400 m: β = 1.6, 95% CI: 0.3, 2.9) and %FVC (200 m: β = 1.8, 95% CI: 0.7, 3.0; 400 m: β = 1.6, 95% CI: 0.3, 2.8; 800 m: β = 1.5, 95% CI: 0.1, 2.8). Adjusted results for %FEV₁/FVC were non-significant except exposure at birth in the 400 m buffer (β = 0.81, 95% CI: 0.1, 1.5). We found no evidence of effect measure modification of NDVI by atopic status for objective measures of lung function.

CONCLUSION

Sensitivity to allergens may modify the effect of greenness on risk for asthma in children but greenness is likely beneficial for concurrent lung function regardless of allergic status.

Antioxidant Effects of Korean Propolis in HaCaT Keratinocytes Exposed to Particulate Matter 10

Air pollution causes oxidative stress that leads to inflammatory diseases and premature aging of the skin. The purpose of this study was to examine the antioxidant effect of Korean propolis on oxidative stress in human epidermal HaCaT keratinocytes exposed to particulate matter with a diameter of less than 10 μm (PM₁₀). The total ethanol extract of propolis was solvent-fractionated with water and methylene chloride to divide into a hydrophilic fraction and a lipophilic fraction. The lipophilic fraction of propolis was slightly more cytotoxic, and the hydrophilic fraction was much less cytotoxic than the total extract. The hydrophilic fraction did not affect the viability of cells exposed to PM₁₀, but the total propolis extract and the lipophilic fraction aggravated the toxicity of PM₁₀. The total extract and hydrophilic fraction inhibited PM₁₀-induced ROS production and lipid peroxidation in a concentration-dependent manner, whereas the lipophilic fraction did not show such effects. High-performance liquid chromatography with photodiode array detection (HPLC-DAD) analysis showed that the hydrophilic fraction contained phenylpropanoids, such as caffeic acid, p-coumaric acid, and ferulic acid, whereas the lipophilic faction contained caffeic acid phenethyl ester (CAPE). The former three compounds inhibited PM₁₀-induced ROS production, lipid peroxidation, and/or glutathione oxidation, and ferulic acid was the most effective among them, but CAPE exhibited cytotoxicity and aggravated the toxicity of PM₁₀. This study suggests that Korean propolis, when properly purified, has the potential to be used as a cosmetic material that helps to alleviate the skin toxicity of air pollutants.

Overcoming Skin Damage from Pollution via Novel Skincare Strategies

Urban pollution is one of the main problems encountered worldwide with major impact on public health as well as the environment. Health impact of urban pollution is not limited to respiratory conditions but also encompasses major skin problems including irritation, skin ageing, and skin cancer. Toxic gases and particulate matter are the main pollutants and exhibit extensive local variability. The aforementioned pollutants are small particles that attach to the skin or penetrate into it, enhancing free radicals' production inside the inner skin layers. This urges the need to propose cosmetic products that help prevent and/or minimise pollutants' effects on the skin whether irritation, ageing and cancer. Furthermore, intrinsic and extrinsic factors contributed to skin irritation and ageing. Intrinsic factors are within skin factors and include genetic and physiological characteristics of individuals. Moreover, extrinsic factors comprise environmental factors such as humidity, temperature, and smoke. Subsequently active ingredients with antipollutant properties addressed the intrinsic and extrinsic factors by four mechanisms being: free radical neutralisation, film-forming ability, skin barrier enhancement and fortification. Such ingredients include vitamin A derivatives, vitamin C derivatives, carbohydrates, and plant-based products. Yet, very limited studies have evaluated the effectiveness of the aforementioned active ingredients against irritation or ageing and this should be considered in future work.

Air Pollution and Weather Conditions Are Associated with Daily Outpatient Visits of Atopic Dermatitis in Shanghai, China

BACKGROUND

Non-optimum weather conditions and air pollution have the potential to increase the risk of atopic dermatitis (AD), but the associations are rarely evaluated, especially in developing countries.

OBJECTIVE

To investigate the independent influence and interaction effects of meteorological factors and air pollutants on the onset of AD.

METHODS

Daily data on outpatient visits of AD were obtained from Shanghai Dermatology Hospital and comprised 34,633 patients during the period from January 2013 to December 2018. Meteorological conditions and air pollutant concentrations in Shanghai, China, during the 6-year period were collected. We applied the overdispersed generalized additive model and the distributed lag model to explore the short-term cumulative effects of environmental factors on AD.

RESULTS

AD symptoms were aggravated by extreme low temperature (1st percentile, 0.5°C) (RR = 1.32, 95% CI: 1.16-1.51) and per 10 unit decrease of humidity (RR = 1.10, 95% CI: 1.12-2.47). The increased concentration of air pollutants except ozone (O3) contributed to the increased risk of AD outpatients. A 10 μg/m3 increase in sulfur dioxide (SO2) and nitrogen dioxide (NO2) were associated with 6.03% (95% CI: 2.29%, 9.91%), and 1.96% (95% CI: 0.46%, 3.48%) increase of AD outpatients. AD patients in the 8- to 17-year-old group were most susceptible to extreme low temperature, and patients in the 0- to 7-year-old group were most susceptible to air pollutants, including particulate matter (PM10), SO2, and NO2. Men were more sensitive to the effects of extreme low temperature than women, while women were more vulnerable to air pollutants. The adverse effects of SO2 and NO2 on AD can be enhanced significantly by the warm season or other pollutants.

CONCLUSION

Exposure to a lower temperature, lower humidity, and higher levels of air pollutants is significantly associated with increased risks of AD incidence. These impacts were more pronounced in children less than 7 years old, women, and warm seasons.

Oxidative Stress and Gut Microbiome in Inflammatory Skin Diseases

Oxidative stress plays a dominant role in inflammatory skin diseases. Emerging evidence has shown that the close interaction occurred between oxidative stress and the gut microbiome. Overall, in this review, we have summarized the impact of oxidative stress and gut microbiome during the progression and treatment for inflammatory skin diseases, the interactions between gut dysbiosis and redox imbalance, and discussed the potential possible role of oxidative stress in the gut-skin axis. In addition, we have also elucidated the promising gut microbiome/redox-targeted therapeutic strategies for inflammatory skin diseases.

Personal Exposure to Total VOC Is Associated With Symptoms of Atopic Dermatitis in Schoolchildren

BACKGROUND

The urinary levels of volatile organic compound (VOC) metabolites provide individual exposure levels compared to data obtained by measuring these compounds in ambient air. We aimed to investigate the association between personal urinary concentrations of VOC metabolites and symptoms of atopic dermatitis in schoolchildren.

METHODS

Nine urinary VOC metabolites were analyzed from urine samples of 149 children. Diagnosis of atopic dermatitis was determined using standardized questionnaires. Pediatricians visited the schools and rated the severity of symptoms using the SCORing Atopic Dermatitis (SCORAD) in all children.

RESULTS

Forty-five children (30.2%) had atopic dermatitis based on the International Study of Asthma and Allergies in Childhood (ISAAC) results and 35 children (23.8%) had symptoms of atopic dermatitis with positive SCORAD index values (defined as SCORAD ≥ 5). Children with benzylmercapturic acid detected in personal urines were associated with presence of atopic dermatitis and positive SCORAD index values. Children in the highest quartile of mandelic acid concentration were associated with presence of atopic dermatitis and positive SCORAD results.

CONCLUSION

Personal exposure to VOCs, as indicated by urinary levels of VOC metabolites, was associated with presence of atopic dermatitis and the SCORAD index value.

Modeling of Temporal Exposure to the Ambient Environment and Eczema Severity

Atopic eczema is a common and complex disease. Missing genetic hereditability and increasing prevalence in industrializing nations point toward an environmental driver. We investigated the temporal association of weather and pollution parameters with eczema severity. This cross-sectional clinical study was performed between May 2018 and March 2020 and is part of the Tower Hamlets Eczema Assessment. All participants had a diagnosis of eczema, lived in East London, were of Bangladeshi ethnicity, and were aged <31 years. The primary outcome was the probability of having an Eczema Area and Severity Index score > 10 after previous ambient exposure to commonly studied meteorological variables and pollutants. There were 430 participants in the groups with Eczema Area and Severity Index ≤ 10 and 149 in those with Eczema Area and Severity Index > 10. Using logistic generalized additive models and a model selection process, we found that tropospheric ozone averaged over the preceding 270 days was strongly associated with eczema severity alongside the exposure to fine particles with diameters of 2.5 μm or less (fine particulate matter) averaged over the preceding 120 days. In our models and analyses, fine particulate matter appeared to largely act in a supporting role to ozone. We show that long-term exposure to ground-level ozone at high levels has the strongest association with eczema severity.

Time Trends in the Prevalence of Atopic Dermatitis in Korean Children According to Age

This study aimed to explore time trends in the prevalence of atopic dermatitis (AD) according to age in Korean children. We observed changes in the estimated annual prevalence of AD using data from the Korean National Health Insurance Service (NHIS) and Statistics Korea between 2003 and 2018. In each year, the highest prevalence was evident among children aged 12 to 23 months, and then the prevalence decreased with age. The annual prevalence of AD in Korean children under the age of 18 slightly increased from 4.0% in 2003 to 4.5% in 2018. During this period, the prevalence in children aged 6 to 18 years increased from 1.9% in 2003 to 3.1% in 2018, while that of infants aged less than 24 months substantially decreased. Among children who were born in 1991, 1997, 2000, 2003 and 2006, the slopes of decreasing trend lines over age 6 were similar. Comparing children born in 2009 and 2012 with those born before 2006, the more recent the birth year, the higher the prevalence of AD over age 6. In conclusion, time trends of the annual prevalence of AD in Korean children from 2003 through 2018 were different according to age group. These results suggest that AD development during infancy is decreasing whereas either a late-onset AD or early-onset, persistent phenotype is likely to increase. Different strategies according to age are required for more effective prevention and treatment of AD in Korean children.

Development of In Vitro Co-Culture Model to Mimic the Cell to Cell Communication in Response to Urban PM2.5

Background

Airborne particulate matter (PM), a widespread air contaminant, is a complex mixture of solids and aerosols composed of particles suspended in the air. PM is associated with inflammatory responses and may worsen inflammatory skin diseases. However, the mechanisms through which PM affects atopic dermatitis (AD) remain unclear.

Objective

To establish an in vitro model that more accurately mimics AD using human keratinocyte (HaCaT), dermal fibroblast (HDF), and mast cell (HMC-1) and using this model to investigate the mechanism through which PMs affect AD.

Methods

An AD-like in vitro model was established by seeding HaCaT, HDF, and HMC-1 cells with recombinant human interleukin (IL)-1α and polyinosinic:polycytidylic acid. We confirmed the effect of PM on the inflammatory cytokine expression of a triple-cell culture model. SRM 1649b Urban Dust, which is mainly composed of polycyclic aromatic hydrocarbons, was used as the reference PM. The effects of PM on the expression levels of proinflammatory cytokines and skin barrier markers were assessed using quantitative real-time polymerase chain reaction and western blotting. Inflammatory cytokine levels were measured using an enzyme-linked immunosorbent assay.

Results

Interactions between various skin cell types were evaluated using a co-culture system. PM treatment increased mRNA and protein levels of the inflammatory cytokines IL-6, IL-1α, tumor necrosis factor-α, IL-4, and IL-1β and decreased the expression of the skin barrier markers filaggrin and loricrin.

Conclusion

Our results suggest that an in vitro triple-cell culture model using HaCaT, HDF, and HMC-1 cells may be reliable for obtaining more physiological, functional, and reproducible data on AD and skin barriers.

[Climate crisis and its impact on human health]

The climate crisis and its consequences represent the greatest challenge facing human health and health care system in the 21st century. It threatens to undermine the last decades of health gains. Rising temperatures, fires, floods and droughts can directly and indirectly cause human pathologies, that are physical and mental. Extreme weather events lead to loss of life, basic life resources and cause severe mental burden. More intense and frequent heat waves due to global warming impact human health and increase mortality, especially for those most vulnerable. The heat-related health risk depends on individual state of health as well as environmental and socioeconomic characteristics of residential areas. Increasing exposure to air pollutants, due to wildfires and anthropogenic emissions, raises respiratory and cardiovascular mortality. Climate warming changes ecosystems and enhances biological invasions that can better adapt to warm environments. Pathogen profiles are changing, transmission and spread of vector-borne diseases as Malaria or Dengue are increasing. Further, rising temperatures and air pollution increase the production and allergenicity of pollen, associated with higher prevalence of allergic diseases. Protective environmental factors, as biodiversity or diverse microbiome, should be given greater consideration in future research.Health sector has the central responsibility as the fifth-largest greenhouse gas emitter to transform in a climate-neutral and sustainable way, e. g. by efficient use of resources. Further education and training in this area should be intensified and included in curricula for medical staff. Furthermore, medical professionals must educate patients about the burden of climate change, climate resilience, and the benefits of CO2 reduction - for human but also for planetary health.