Effects and mechanisms of polycyclic aromatic hydrocarbons in inflammatory skin diseases

Polycyclic aromatic hydrocarbon-aryl hydrocarbon receptor signaling regulates chronic inflammation in lung-gut axis

Polycyclic aromatic hydrocarbons (PAHs) are broadly identified in environmental pollutants and also formed during the heat processing of meat, including grilling, roasting, smoking, and frying, particularly at high temperatures. Besides, the PAHs influence inflammatory response through activation of aryl hydrocarbon receptor (AhR) signaling. Recently, the role of the PAHs/AhR axis in inflammatory diseases has attracted major attention in the regulation of lung function, gut barrier function, and systemic inflammation. Many experiments have been conducted to determine the role of the PAHs/AhR/cytochrome P450 1A1 signaling activation on elevation of inflammation in the lung-gut axis. In contrast, several dietary AhR ligands can improve inflammatory function by modulating the AhR signaling, thereby strengthening the intestinal barrier. This review includes the pivotal roles of xenobiotic and diet-derived AhR ligands in the regulation of chronic lung diseases and systemic inflammation and their relevance in the lung-gut axis.

Exploring the toxicological impact of bisphenol a exposure on psoriasis through network toxicology, machine learning, and multi-dimensional bioinformatics analysis

Psoriasis is a common immune - mediated skin disease, the pathogenesis of which is not completely elucidated. Environmental factors are key to its onset and progression. Bisphenol A (BPA) is a ubiquitous environmental pollutant that endangers human health. Previous research shows that BPA exposure disrupts immunity and causes skin inflammation and autoimmune diseases. However, the role and molecular mechanisms of BPA in psoriasis are unclear. In this study, we used network toxicology, machine learning, and bioinformatics to study BPA - induced psoriasis mechanisms. Public database analyses identified 100 potential targets, with significant enrichment in the PI3K - AKT and Chemokine signaling pathways. Machine learning identified five core targets: PTAFR, MMP9, CXCR2, IDO1, and LCK. These genes are highly expressed in psoriatic lesion tissues than controls and associated to immune cell infiltration. Molecular docking and dynamics simulations confirmed stable interactions between BPA and these targets, which supports their role in disease progression. We also developed a novel Adverse Outcome Pathway (AOP) framework for BPA-induced psoriasis, providing key toxicological insights into the risks of exposure. These findings highlight the impact of BPA on immune regulation, offering a foundation for understanding associated health risks and formulating mitigation strategies. Our study provides an in-depth exploration of the molecular mechanisms underlying BPA-induced psoriasis. The findings underscore the practical application of integrating network toxicology, machine learning, multidimensional bioinformatics approaches, and AOP frameworks in assessing environmental pollutant risks. Furthermore, it lays the foundation for understanding BPA-related health risks and developing strategies to mitigate its impact on psorasis.

Skin conditions associated with dermal exposure to oil spill chemicals among Deepwater Horizon disaster response and cleanup workers

BACKGROUND

Previous studies have associated oil spill response and cleanup (OSRC) work with skin symptoms, but evidence is lacking on the specific exposure agents that contributed to these skin effects.

OBJECTIVES

We investigated OSRC-related exposures, including dermal exposure to specific chemical agents, in relation to acute and longer-term skin conditions among the 2010 Deepwater Horizon (DWH) OSRC workers.

METHODS

At GuLF Study enrollment, workers reported duration of work, jobs performed, and skin contact with crude oil/tar, dispersants, and decontamination chemicals. Cumulative dermal exposure to polycyclic aromatic hydrocarbons (PAHs) from oil/tar was estimated based on the "GuLF DREAM model". We used Poisson regression with robust standard errors to evaluate associations of exposures with prevalent skin conditions during spill cleanup and at enrollment (1-3 years later) and incident eczema diagnoses after the start of OSRC work. We examined modification of associations between exposures and prevalent conditions by use of rubber/synthetic gloves.

RESULTS

Duration of OSRC work was positively associated with skin conditions and eczema diagnoses (p-trend<0.01). Workers in operations, response, and decontamination jobs had higher skin condition prevalence (during cleanup: PR range=3.13-4.51; at enrollment: PR range=2.20-2.94) and eczema risk (RR range=1.44-1.89) compared to support workers. After adjusting for co-exposures, we saw associations of skin conditions during cleanup with dermal exposure to oil/tar (PR=3.41, 95 %CI: 3.14, 3.69), decontamination chemicals (PR=1.55, 95 %CI: 1.46, 1.64), dispersants (PR=1.44, 95 %CI: 1.33, 1.57), and PAHs (p-trend<0.01). These associations remained apparent at enrollment. Eczema diagnosis was associated with exposure to oil/tar (RR=1.56, 95 %CI: 1.20, 2.04) and PAHs (Tertile 3 vs. 1: PR=1.33, 95 %CI: 0.86, 2.07). Effect estimates were on average 21 % lower among workers who used rubber/synthetic gloves.

CONCLUSIONS

Duration of work, working in non-support jobs, and dermal exposure to oil/tar, dispersants, decontamination chemicals, and PAHs were associated with acute and longer-term skin effects among the DWH OSRC workers.

Emerging Contaminants: An Important But Ignored Risk Factor for Psoriasis

Industrialization and modernization have changed the environment. A group of emerging contaminants (ECs) has been defined recently. Psoriasis, whose incidence has increased in recent years, is a relapsing immune-mediated disease carrying a heavy disease burden. The erythematous scaly plaque is a typical symptom and occurs on several parts of the body. In addition, psoriasis has many comorbidities, such as psoriatic arthritis, diabetes, and depression, damaging the quality of life of patients. IL-17, IL-12, IL-23, and TNF-alpha are important related cytokines. ECs can influence psoriasis through the immune system and inflammatory responses. Specific mechanisms include increasing pro-inflammatory cytokines such as TNF-α and IL-17, and activating immune cells such as macrophages. And for psoriasis patients, it is suggested to reduce the exposure of most ECs. However, the complex mechanisms involved have not been discussed together and concluded. In this review, we summarize the relationship between ECs and psoriasis, focusing on the immune system, especially the immune cells and cytokines. These results can help guide clinical treatment and long-term management of psoriasis.

Skin sensitizers enhance superoxide formation by polycyclic aromatic hydrocarbons via the aldo-keto reductase pathway

Exposure to combustion-derived airborne polycyclic aromatic hydrocarbons (PAHs) may harm human skin, exacerbate cutaneous inflammatory diseases and accelerate skin aging. The toxicity of PAHs is unleashed upon their metabolic activation by cytochrome P450 (CYP) 1 monooxygenases, resulting in the formation of reactive intermediates that form mutagenic DNA adducts. Moreover, PAHs cause oxidative stress, which is primarily due to aldo-keto reductases (AKRs), such as AKR1C3, which convert CYP1-derived PAH-trans-diols to PAH-catechols. The catechols undergo autooxidation leading to the formation of reactive oxygen species (ROS) and PAH-quinones. The latter are highly reactive, mitotoxic and are reduced back to PAH-catechols, thus facilitating redox cycling. As AKR1C expression is inducible by other NRF2-stimulating chemicals, we tested the hypothesis that co-exposure of HaCaT keratinocytes to skin sensitizers and the PAH benzo[a]pyrene (BaP) enhances ROS formation. We observed a synergistic effect of the skin sensitizers on the BaP-induced expression of the NRF2 target genes heme oxygenase-1, sulfiredoxin-1 and AKR1C3. In fact, co-exposure to the skin sensitizers also enhanced the BaP-induced formation of superoxide anions. Intriguingly, the co-exposure-related ROS formation was abolished upon inhibition of either CYP1A1 or AKR1C3. Testing of additional skin-sensitizing compounds, differing in their mode of action, indicated that especially potent Michael acceptors enhance the toxicity of BaP by increasing AKR1C3 expression and, presumably, downstream BaP-quinone formation. Our study reveals potential health risks associated with the simultaneous exposure to common skin-sensitizing substances and ubiquitous PAHs, and implies a role for NRF2 in mediating PAH toxicity.

Maternal urinary levels of PAH metabolites, umbilical cord blood telomere length and anthropometric indices in newborns

The existing evidence indicating that prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) is associated with a range of adverse outcomes, including alterations in anthropometric indices, underscores the need for further investigation into the underlying mechanisms. This study aims to examine the effects of prenatal PAH exposure on anthropometric indices and telomere length (TL), as well as to explore whether changes in TL can serve as a predictor of alterations in anthropometric measures. The study was conducted in Shenyang, China, with 2460 pregnant women participating between 2022 and 2023. Maternal urine samples were analyzed for eleven PAH metabolites, and neonatal outcomes, such as birth weight (BW), birth length (BL), and head circumference (HC), were extracted from medical records as anthropometric indices. We employed multiple linear regression (MLR), generalized quantile g-computation (g-comp), Bayesian Kernel Machine Regression (BKMR), and mediation analysis to comprehensively assess the associations between PAH exposure and umbilical TL and neonatal outcomes. Notably, significant negative associations were found between several PAH metabolites and umbilical telomere length (TL). These metabolites included 2-hydroxy naphthalene (2-OH Nap), 1-hydroxy pyrene (1-OH Pyr), 6-hydroxy chrysene (6-OH Chr), 9-hydroxy benzo(a)pyrene (9-OH Bap), and the sum of hydroxylated PAHs (Σ-OH PAHs). Additionally, negative correlations were identified between specific PAH metabolites and HC, although no significant associations were found for BW. Birth weight showed a significant inverse relationship with metabolites such as 1-hydroxy phenanthrene (1-OH Phe), 9-hydroxy phenanthrene (9-OH Phe), and 1-hydroxy naphthalene(1-OH Nap). Results from g-comp analysis and BKMR indicated significant mixture effects of PAHs on umbilical TL and HC, with more heterogeneous effects on BW and BL. Mediation analysis indicated that alterations in umbilical TL partially mediated the associations between PAH exposure and BW and HC. Notably, metabolites such as 2-OH Nap and the Σ-OH PAHs demonstrated substantial mediation effects. Overall, our findings suggest that changes in umbilical TL partially mediate the associations between prenatal PAH exposure and HC and BW, highlighting the complex pathways through which PAH metabolites may influence neonatal development.

Role of AhR-Hsp90-MDM2-mediated VDR ubiquitination in PM2.5-induced renal toxicity

BACKGROUND AND OBJECTIVES

The kidney is a primary target for the accumulation of particulate matter (PM2.5). This study aimed to investigate PM2.5-induced renal toxicity mechanisms, focusing on the aryl hydrocarbon receptor (AhR)-Hsp90-MDM2 axis and its impact on vitamin D receptor (VDR) ubiquitination.

METHODS

PM2.5's role in activating the AhR and its downstream pathways was investigated using in vitro and in vivo models. Renal damage and therapeutic effects in PM2.5-exposed and paricalcitol-treated mice were evaluated using weight measurements, histopathology, and scanning electron microscopy. AhR, Hsp90, and VDR localization and expression in renal cells were assessed using FISH and Western blot. Protein interactions were examined using co-immunoprecipitation. Differentially expressed gene (DEG) analysis of GEO datasets was used to identify related proteins and genes.

RESULTS

PM2.5 exposure caused significant renal damage in mice, including increased serum creatinine, albuminuria, and histopathological deterioration, which were alleviated by paricalcitol. PM2.5 induced the nuclear translocation of AhR and Hsp90 and reduced nuclear VDR expression; paricalcitol reversed these effects. Immunohistochemistry confirmed these findings. PM2.5 upregulated the NLRP3/caspase-1/IL-1β/IL-18 axis, which was reversed by paricalcitol treatment. Inhibition of Hsp90 increased nuclear VDR expression through MDM2 mediation. DEG analysis identified VDR-regulated genes; PM2.5 increased the mRNA levels of IL-6, IL-2, and CXCL8, which were downregulated by Hsp90 and MDM2 inhibitors, with VDR agonists further decreasing these levels.

CONCLUSION

This study reveals a novel mechanism of PM2.5-induced renal toxicity through the AhR-Hsp90-MDM2 axis, promoting VDR ubiquitination and degradation and increasing inflammation. These findings provide a foundation for future studies and lay the groundwork for developing targeted interventions to mitigate the public health impact of PM2.5 exposure.

Impact of urinary PAHs on psoriasis risk in U.S. adults: Insights from NHANES

OBJECTIVE

Exposure to environmental pollutants is increasingly recognized as a risk factor for the development of psoriasis. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the air and might induce reactions such as oxidative stress. Nevertheless, it is still unclear if PAHs have any influence on the prevalence of psoriasis over the entire population of the United States. The objective of this study was to assess the association between urine PAHs and psoriasis.

METHODS

The research included 3,673 individuals aged 20 years or older who participated in the 2003-2006 and 2009-2012 National Health and Nutrition Examination Surveys (NHANES). We employed logistic regression models to evaluate the relationship between levels of urine PAH metabolites and psoriasis and smoothed curve fitting to illustrate the concentration-response relationship. Additionally, subgroup and interaction analyses were conducted to elucidate these associations. Furthermore, we employed weighted quartile sum (WQS) regressions to examine the distinct effects of individual and mixed urine PAH metabolites on psoriasis. However, it is important to note that the NHANES sample may be subject to selectivity and self-reporting bias, which may influence the data' generalisability.

RESULTS

We observed that the highest tertiles of 2-NAP and 2-FLU had a 63% (95% CI 1.02, 2.61) and 83% (95% CI 1.14, 2.96) higher odds of association with psoriasis prevalence, respectively. Meanwhile, tertile 2 and tertile 3 of 3-PHE were also significantly associated with psoriasis, with higher odds of 65% (95% CI 1.01, 2.69) and 14% (95% CI 1.17, 3.00), respectively. The subgroup analyses revealed a significant correlation between urine PAH metabolites and the odds of psoriasis in specific groups, including males, aged 40-60 years, with a BMI > 30, and those with hyperlipidemia. In the WQS model, a positive association was found between the combination of urine PAH metabolites and psoriasis (OR 1.43, 95% CI 1.11, 1.84), with 2-FLU being the most prevalent component across all mixtures (0.297).

CONCLUSIONS

Our findings indicate a significant association between urine PAH metabolites and the odds of psoriasis prevalence in adults. Among these metabolites, 2-FLU demonstrated the most prominent impact. Controlling PAH exposure, as an important strategy for minimizing exposure to environmental contaminants and lowering the risk of psoriasis, is critical for raising public knowledge about environmental health and preserving public health.

Particulate Matter-Induced Emerging Health Effects Associated with Oxidative Stress and Inflammation

Environmental pollution continues to increase with industrial development and has become a threat to human health. Atmospheric particulate matter (PM) was designated as a Group 1 carcinogen by the International Agency for Research on Cancer in 2013 and is an emerging global environmental risk factor that is a major cause of death related to cardiovascular and respiratory diseases. PM is a complex composed of highly reactive organic matter, chemicals, and metal components, which mainly cause excessive production of reactive oxygen species (ROS) that can lead to DNA and cell damage, endoplasmic reticulum stress, inflammatory responses, atherosclerosis, and airway remodeling, contributing to an increased susceptibility to and the exacerbation of various diseases and infections. PM has various effects on human health depending on the particle size, physical and chemical characteristics, source, and exposure period. PM smaller than 5 μm can penetrate and accumulate in the alveoli and circulatory system, causing harmful effects on the respiratory system, cardiovascular system, skin, and brain. In this review, we describe the relationship and mechanism of ROS-mediated cell damage, oxidative stress, and inflammatory responses caused by PM and the health effects on major organs, as well as comprehensively discuss the harmfulness of PM.

Photodegradation enhances the toxic effect of anthracene on skin

Anthracene, a polycyclic aromatic hydrocarbon (PAH), is a widespread environmental pollutant that poses potential risks to human health. Exposure to anthracene can result in various adverse health effects, including skin-related disorders. Photo exposure sufficiently removes the anthracene from the environment but also generates more degradation products which can be more toxic. The goal of this study was to assess the change in anthracene dermotoxicity caused by photodegradation and understand the mechanism of this change. In the present study, over 99.99% of anthracene was degraded within 24 h of sunlight exposure, while producing many intermediate products including 9,10-anthraquinone and phthalic acid. The anthracene products with different durations of photo exposure were applied to 2D and 3D human keratinocyte cultures. Although the non-degraded anthracene significantly delayed the cell migration, the cell viability and differentiation decreased dramatically in the presence of the photodegraded anthracene. Anthracene photodegradation products also altered the expression patterns of a number of inflammation-related genes in comparison to the control cells. Among these genes, il1a, il1b, il8, cxcl2, s100a9, and mmp1 were upregulated whereas the tlr4 and mmp3 were downregulated by the photodegraded anthracene. Topical deliveries of the photodegraded and non-degraded anthracene to the dorsal skin of hairless mice showed more toxic effects by the photodegraded anthracene. The 4-hour photodegradation products of anthracene thickened the epidermal layer, increased the dermal cellularity, and induced the upregulation of inflammatory markers, il1a, il1b, s100a9, and mmp1. In addition, it also prevented the production of a gap junction protein, Connexin-43. All the evidence suggested that photodegradation enhanced the toxicities of anthracene to the skin. The 4-hour photodegradation products of anthracene led to clinical signs similar to acute inflammatory skin diseases, such as atopic and contact dermatitis, eczema, and psoriasis. Therefore, the potential risk of skin irritation by anthracene should be also considered when an individual is exposed to PAHs, especially in environments with strong sunlight.