The skin is no barrier to mixtures: Air pollutant mixtures and reported psoriasis or eczema in the Personalized Environment and Genes Study (PEGS)

The role of C-reactive protein and genetic predisposition in the risk of psoriasis: results from a national prospective cohort

BACKGROUND

Psoriasis is an immune-mediated chronic inflammatory disease associated with multiple factors. To evaluate the extent to which C-reactive protein (CRP) and genetic predisposition affect the incidence of psoriasis.

METHODS

The cohort study retrieved 420,040 participants without psoriasis at baseline from the UK Biobank. Serum CRP was categorized into two levels: < 2 mg/L (normal) and ≥ 2 mg/L (elevated). The polygenic risk score (PRS) was used to estimate genetic predisposition, and was characterized as low, moderate and high PRS. The possible interaction and joint associations between CRP and PRS were assessed using Cox proportional hazards models.

RESULTS

Participants with high CRP levels had an increased risk of incident psoriasis compared to those with low CRP levels (HR: 1.26, 95% CI: 1.18-1.34). Participants with high CRP levels and high PRS had the highest risk of incident psoriasis [2.24 (95% CI: 2.01, 2.49)], compared with those had low CRP levels and low PRS. Significant additive and multiplicative interaction were found between CRP and PRS in relation to the incidence of psoriasis.

CONCLUSIONS

Our results suggest that higher CRP concentration may be associated with higher psoriasis incidence, with a more pronounced association observed in individuals with high PRS for psoriasis. So, clinicians should be aware that the risk of incident psoriasis may increase in general population with high CRP levels and high PRS, so that early investigation and intervention can be initiated.

Lifetime incidence and healthcare disparities in alopecia areata: a UK population-based cohort study

BACKGROUND

Alopecia areata (AA) is an immune-mediated form of hair loss that can occur at any age, often with a significant mental health burden.

OBJECTIVES

We aimed to provide estimates of the lifetime incidence of AA, and the impacts on mental health, healthcare utilization and work-related outcomes, assessing variation across major sociodemographic subgroups.

METHODS

AA cases were identified in primary care from the UK population-based Oxford-Royal College of General Practitioners Research and Surveillance Centre database (2009-2018). Lifetime incidence of AA was estimated at age 80 years using modified time-to-event models with age as the timescale, overall and stratified by sex, ethnicity, deprivation and geography. Mental health, healthcare utilization and work-related outcomes were assessed in the 2 years after AA diagnosis compared with matched unaffected controls, and stratified by the same sociodemographic subgroups.

RESULTS

During the study period, 6961 people developed AA. Overall lifetime incidence of AA was 2.11% [95% confidence interval (CI) 2.06-2.16]. Females had a higher lifetime incidence (2.35%, 95% CI 2.28-2.43) than males (1.88%, 95% CI 1.81-1.94). Lifetime incidence was higher in those of Asian ethnicity (5.87%, 95% CI 5.51-6.24), Other (4.5%, 95% CI 3.63-5.31), Mixed (4.4%, 95% CI 3.50-5.37) and Black (3.0%, 95% CI 2.63-3.42) ethnicity, compared with White ethnicity (1.7%, 95% CI 1.68-1.80). Lifetime incidence was highest in those with the greatest deprivation: most-deprived quintile (2.92%, 95% CI 2.77-3.07) compared with least-deprived (1.68%, 95% CI 1.59-1.78). Across sociodemographic subgroups, people with AA of Black ethnicity were most likely to have anxiety (adjusted odds ratio vs. matched controls 2.92, 95% CI 1.71-4.91), and had the greatest risk of time off work (adjusted hazard ratio vs. matched controls 2.54, 95% CI 1.80-3.56).

CONCLUSIONS

AA affects around 1 in 50 people over their lifetime. The incidence and impact of AA on mental health and work outcomes is highest in ethnic groups other than White. Clinicians should be aware of the marked heterogeneity in the incidence and impact of AA, and support targeted healthcare to groups at the highest risk of alopecia and its consequences.

Systematic establishment of the relationship between skin absorption and toxicity of furanoids via in silico, in vitro, and in vivo assessments

Furanoids are a class of contaminants prevalent in both airborne and occupational environments, with potential health implications through inhalation, oral ingestion, and skin penetration. Given their diminutive molecular size, there is a presumption that furanoids can readily permeate the skin. To systematically explore this presumption, we investigated the skin absorption and toxicity of a series of furans (furfuryl alcohol, furfuryl acetate, furfural, methyl 2-furoate, and 5-methylfurfural) using in silico, in vitro, and in vivo models. The in vitro permeation test (IVPT) from neat and aqueous suspension (5 mM) of furans demonstrated a facile absorption through pig and nude mouse skins. The lipophilicity of furans significantly influenced skin deposition, with higher lipophilicity displaying greater deposition. However, an opposing trend emerged in the receptor compartment accumulation. In barrier-defective skin simulating atopic dermatitis (AD) and psoriasis, enhanced deposition occurred with more hydrophilic furans but not with the more lipophilic ones. In the cell-based study, furanoids induced the proliferation of keratinocytes and skin fibroblasts except for the compounds with the aldehyde group (furfural and 5-methylfurfural). Both furfuryl acetate and 5-methylfurfural activated keratinocytes via the overexpression of COX-2 and PGE2 by 1.5‒2-fold. This stimulation involved the mitogen-activated protein kinase (MAPK) signaling pathway. For the in vivo mouse skin treatment, we selected furfuryl acetate (hydrophilic) and 5-methylfurfural (lipophilic). Both furans showed different patterns of skin lesions, where repeated application of furfuryl acetate caused epidermal hyperplasia and scaling, while 5-methylfurfural predominantly evoked skin inflammation and barrier disintegration. Toxicokinetics analysis revealed a higher plasma concentration of topically applied furfuryl acetate than that of the 5-methylfurfural (5.04 versus 2.34 nmol/ml), resulting in the mild injury of furfuryl acetate-treated peripheral organs. Conversely, no notable adverse effects on organs were observed for the 5-methylfurfural. This study established the relationship between cutaneous absorption and the toxicity of furans following skin exposure.

Association between fine particulate matter and eczema: A cross-sectional study of the All of Us Research Program and the Center for Air, Climate, and Energy Solutions

BACKGROUND

The prevalence of eczema has increased with industrialization. Industrial practices generate ambient air pollution, including fine particulate matter of diameter ≤ 2.5μm (PM2.5). Studies investigating the relationship between PM2.5 and eczema in the US are scarce. The objective of this study was to determine the risk of eczema with PM2.5 exposure in a diverse national cohort of American adults.

METHODS

In this cross-sectional study, eczema cases in the All of Us Research Program were linked via three-digit zip code to average annual PM2.5 concentrations from the Center for Air, Climate, and Energy Solutions. Eczema cases and controls were compared using Pearson's χ2 test for categorical variables and one-way analysis of variance for continuous variables. The relationship between PM2.5 and eczema was assessed via logistic regression adjusting for demographic factors, smoking, and atopic comorbidities.

RESULTS

Individuals with eczema (n = 12,695) lived in areas with significantly higher PM2.5 concentrations than did individuals without eczema (n = 274,127) (0.83 x 10 μg/m3 v. 0.81 x 10 μg/m3, P < .001). PM2.5 concentration was significantly associated with eczema in univariable analysis (odds ratio 1.97, 95% confidence interval 1.77-2.19, P < .001), and in multivariable analyses, both controlling for demographics and smoking status (odds ratio 2.21, 95% confidence interval 1.98-2.47, P < .001) and with the addition of atopic comorbidities (odds ratio 2.38, 95% confidence interval 2.12-2.67, P < .001).

CONCLUSIONS

The odds of eczema increased with greater PM2.5 concentration in this large, diverse, adult American cohort. Ambient air pollution is an environmental hazard that influences inflammatory skin disease, suggesting possible targeted interventions.

Association between United States Environmental Contaminants and the Prevalence of Psoriasis Derived from the National Health and Nutrition Examination Survey

(1) Background: Prolonged coexposure to environmental contaminants is reportedly associated with adverse impacts on skin health. However, the collective effects of contaminant mixtures on psoriasis prevalence remain unclear. (2) Methods: A nationally representative cohort study was conducted using data from the National Health and Nutrition Examination Survey 2003-2006 and 2009-2014. The association between contaminant exposures and psoriasis prevalence was analyzed through weighted quantile sum regressions, restricted cubic splines, and multivariable logistic regression. (3) Results: 16,453 participants and 60 contaminants in 8 groups were involved. After adjusting for demographics and comorbidities, exposure to urinary perchlorate, nitrate, and thiocyanate mixtures (OR: 1.10, 95% CI: 1.00-1.21) demonstrated a significant positive linear association with psoriasis prevalence. Ethyl paraben (OR: 1.21, 95% CI: 1.02-1.44) exhibited a significant positive correlation with psoriasis risk as an individual contaminant. The association between blood cadmium, lead, and mercury mixtures (OR: 1.10, 95% CI: 1.00-1.21), urinary perchlorate, nitrate, and thiocyanate mixtures (OR: 1.16, 95% CI: 1.00-1.34), and psoriasis prevalence was more pronounced in the lower healthy lifestyle score subgroup. (4) Conclusions: Exposure to perchlorate, nitrate, and thiocyanate mixtures, and ethyl paraben was associated with an elevated psoriasis prevalence. Furthermore, the association between cadmium and lead and mercury mixtures as well as perchlorate, nitrate and thiocyanate mixtures, and psoriasis prevalence was more pronounced in individuals with less healthy lifestyles.

Combined Exposures and Mixtures Research: An Enduring NIEHS Priority

BACKGROUND

The National Institute of Environmental Health Sciences (NIEHS) continues to prioritize research to better understand the health effects resulting from exposure to mixtures of chemical and nonchemical stressors. Mixtures research activities over the last decade were informed by expert input during the development and deliberations of the 2011 NIEHS Workshop "Advancing Research on Mixtures: New Perspectives and Approaches for Predicting Adverse Human Health Effects." NIEHS mixtures research efforts since then have focused on key themes including a) prioritizing mixtures for study, b) translating mixtures data from in vitro and in vivo studies, c) developing cross-disciplinary collaborations, d) informing component-based and whole-mixture assessment approaches, e) developing sufficient similarity methods to compare across complex mixtures, f) using systems-based approaches to evaluate mixtures, and g) focusing on management and integration of mixtures-related data.

OBJECTIVES

We aimed to describe NIEHS driven research on mixtures and combined exposures over the last decade and present areas for future attention.

RESULTS

Intramural and extramural mixtures research projects have incorporated a diverse array of chemicals (e.g., polycyclic aromatic hydrocarbons, botanicals, personal care products, wildfire emissions) and nonchemical stressors (e.g., socioeconomic factors, social adversity) and have focused on many diseases (e.g., breast cancer, atherosclerosis, immune disruption). We have made significant progress in certain areas, such as developing statistical methods for evaluating multiple chemical associations in epidemiology and building translational mixtures projects that include both in vitro and in vivo models.

DISCUSSION

Moving forward, additional work is needed to improve mixtures data integration, elucidate interactions between chemical and nonchemical stressors, and resolve the geospatial and temporal nature of mixture exposures. Continued mixtures research will be critical to informing cumulative impact assessments and addressing complex challenges, such as environmental justice and climate change. https://doi.org/10.1289/EHP14340.

Causal association between air pollution and autoimmune diseases: a two-sample Mendelian randomization study

Background

In recent years, an increasing number of observational studies have reported the impact of air pollution on autoimmune diseases (ADs). However, no Mendelian randomization (MR) studies have been conducted to investigate the causal relationships. To enhance our understanding of causality, we examined the causal relationships between particulate matter (PM) and nitrogen oxides (NOx) and ADs.

Methods

We utilized genome-wide association study (GWAS) data on PM and NOx from the UK Biobank in European and East Asian populations. We also extracted integrated GWAS data from the Finnish consortium and the Japanese Biobank for two-sample MR analysis. We employed inverse variance weighted (IVW) analysis to assess the causal relationship between PM and NOx exposure and ADs. Additionally, we conducted supplementary analyses using four methods, including IVW (fixed effects), weighted median, weighted mode, and simple mode, to further investigate this relationship.

Results

In the European population, the results of MR analysis suggested a statistically significant association between PM2.5 and psoriasis only (OR = 3.86; 95% CI: 1.89-7.88; PIVW < 0.00625), while a potential association exists between PM2.5-10 and vitiligo (OR = 7.42; 95% CI: 1.02-53.94; PIVW < 0.05), as well as between PM2.5 and systemic lupus erythematosus (OR = 68.17; 95% CI: 2.17-2.1e+03; PIVW < 0.05). In East Asian populations, no causal relationship was found between air pollutants and the risk of systemic lupus erythematosus and rheumatoid arthritis (PIVW > 0.025). There was no pleiotropy in the results.

Conclusion

Our results suggest a causal association between PM2.5 and psoriasis in European populations. With the help of air pollution prevention and control, the harmful progression of psoriasis may be slowed.

Protective Potential of a Botanical-Based Supplement Ingredient against the Impact of Environmental Pollution on Cutaneous and Cardiopulmonary Systems: Preclinical Study

Air pollution is a growing threat to human health. Airborne pollution effects on respiratory, cardiovascular and skin health are well-established. The main mechanisms of air-pollution-induced health effects involve oxidative stress and inflammation. The present study evaluates the potential of a polyphenol-enriched food supplement ingredient comprising Lippia citriodora, Olea europaea, Rosmarinus officinalis, and Sophora japonica extracts in mitigating the adverse effects of environmental pollution on skin and cardiopulmonary systems. Both in vitro and ex vivo studies were used to assess the blend's effects against pollution-induced damage. In these studies, the botanical blend was found to reduce lipid peroxidation, inflammation (by reducing IL-1α), and metabolic alterations (by regulating MT-1H, AhR, and Nrf2 expression) in human skin explants exposed to a mixture of pollutants. Similar results were also observed in keratinocytes exposed to urban dust. Moreover, the ingredient significantly reduced pollutant-induced ROS production in human endothelial cells and lung fibroblasts, while downregulating the expression of apoptotic genes (bcl-2 and bax) in lung fibroblasts. Additionally, the blend counteracted the effect of urban dust on the heart rate in zebrafish embryos. These results support the potential use of this supplement as an adjuvant method to reduce the impact of environmental pollution on the skin, lungs, and cardiovascular tissues.

Interactive data sharing for multiple questionnaire-based exposome-wide association studies and exposome correlations in the Personalized Environment and Genes Study

The correlations among individual exposures in the exposome, which refers to all exposures an individual encounters throughout life, are important for understanding the landscape of how exposures co-occur, and how this impacts health and disease. Exposome-wide association studies (ExWAS), which are analogous to genome-wide association studies (GWAS), are increasingly being used to elucidate links between the exposome and disease. Despite increased interest in the exposome, tools and publications that characterize exposure correlations and their relationships with human disease are limited, and there is a lack of data and results sharing in resources like the GWAS catalog. To address these gaps, we developed the PEGS Explorer web application to explore exposure correlations in data from the diverse North Carolina-based Personalized Environment and Genes Study (PEGS) that were rigorously calculated to account for differing data types and previously published results from ExWAS. Through globe visualizations, PEGS Explorer allows users to explore correlations between exposures found to be associated with complex diseases. The exposome data used for analysis includes not only standard environmental exposures such as point source pollution and ozone levels but also exposures from diet, medication, lifestyle factors, stress, and occupation. The web application addresses the lack of accessible data and results sharing, a major challenge in the field, and enables users to put results in context, generate hypotheses, and, importantly, replicate findings in other cohorts. PEGS Explorer will be updated with additional results as they become available, ensuring it is an up-to-date resource in exposome science.