Long-term environmental surveillance of PM2.5-bound polycyclic aromatic hydrocarbons in Jinan, China (2014-2020): Health risk assessment

Chrysene contribution to bronchial asthma: Activation of TRPA1 disrupts bronchial epithelial barrier via ERK pathway

BACKGROUND

Elevated polycyclic aromatic hydrocarbon (PAH) levels are associated with exacerbation of asthma. Chrysene is one of the most prevalent unsubstituted PAHs in the environment. Transient receptor potential ankyrin 1 (TRPA1) can be used as a chemoreceptor to detect inhaled stimuli and plays an important role in the occurrence and deterioration of asthma. Whether exposure to a high concentration of chrysene in the environment can activate TRPA1 and contribute to the development of asthma, potentially through the dysfunction of the bronchial epithelial barrier, remains unclear.

METHODS

A cell-based assay was performed to verify the downregulation of the expression of E-cadherin and tight junction (TJ) proteins by chrysene in bronchial epithelial cells to explore the role of chrysene-mediated TRPA1 activation in the regulation of TJ protein expression through the extracellular signal-regulated protein kinase (ERK) pathway. Animal tests were conducted to determine whether chrysene could enhance airway hyperresponsiveness (AHR) induced by house dust mites (HDMs) and disrupt barrier function, thereby contributing to asthma.

RESULTS

The cell-based assay revealed that chrysene could disrupt the function of the bronchial epithelial barrier and decrease the expression levels of E-cadherin, zonula occludens-1 (ZO-1), occludin, and claudin-5 through the ERK pathway. Chrysene induced airway epithelial barrier dysfunction primarily through TRPA1 instead of transient receptor potential vanilloid 1. TRPA1 knockdown was able to attenuate chrysene-induced downregulation of TJ protein expression and downregulate ERK activation (p-ERK). Compared with exposure to HDM alone, coexposure to chrysene and HDM resulted in an increased incidence of AHR, disruption of barrier function, and eosinophilic inflammatory responses in a mouse model of asthma. Coexposure to chrysene and HDM increased TRPA1 expression. The animal test verified that the TRPA1 inhibitor HC030031 could suppress chrysene and HDM-induced asthma in mice.

CONCLUSIONS

Our findings showed that chrysene contributed to the breakdown of the function of the bronchial epithelial barrier through the TRPA1-ERK axis and therefore acted as an adjuvant to contribute to asthma.

Benzo[b]fluoranthene damages coronary artery and affects atherosclerosis markers in mice and umbilical vein endothelial cells

Polycyclic aromatic hydrocarbons (PAHs) exposure is associated with cardiovascular diseases. Toxic effects of PAHs are diverse, while cardiovascular consequences of benzo[b]fluoranthene (B[b]F) are unclear. Here, we reported the impacts of B[b]F on coronary artery and atherosclerosis markers both in mice and umbilical vein endothelial EAhy.926 cells. In mice, we found that B[b]F decreases heart-to-body weight ratio, affects aortic physiology, elevates serum low-density lipoprotein and total cholesterol, increases aortic levels of collagen fiber and atherosclerotic marker vascular cell adhesion molecule-1 (VCAM-1), and downregulates oxidative stress related nuclear factor erythroid 2-related factor 2 (Nrf2). In EAhy.926 cells, we showed that B[b]F inhibits cell proliferation and migration in a dose-dependent manner, induces cell cycle arrest and apoptosis, increases reactive oxygen species, upregulates VCAM-1 level, and suppresses expression of Nrf2. Taken together, our findings reveal that B[b]F exposure may contribute to coronary artery damage and potentially induce atherosclerosis, possibly via the Nrf2-related signaling pathways.

Effects of Naphtho[2,1-a]pyrene Exposure on CYP1A1 Expression: An in Vivo and in Vitro Mechanistic Study Exploring the Role of m6A Posttranscriptional Modification

BACKGROUND

Currently, many emerging polycyclic aromatic hydrocarbons (PAHs) have been found to be widely present in the environment. However, little has been reported about their toxicity, particularly in relation to CYP1A1.

OBJECTIVES

This study aimed to explore the toxicity of naphtho[2,1-a]pyrene (N21aP) and elucidate the mechanism underlying N21aP-induced expression of CYP1A1.

METHODS

The concentration and sources of N21aP were detected and analyzed by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) and diagnostic ratio analysis. Then the effects of CYP1A1 on the toxicity of N21aP were conducted in male wild-type (WT) and Cyp1a1 knockout mice exposed to N21aP (0.02, 0.2, and 2 mg / kg ) through intratracheal instillation. Further, the aryl hydrocarbon receptor (AhR) pathway was examined through luciferase and chromatin immunoprecipitation (ChIP) assays. N 6 -methyladenosine (m 6 A ) modification levels were measured on global RNA and specifically on CYP1A1 mRNA using dot blotting and methylated RNA immunoprecipitation-quantitative real-time polymerase chain reaction (MeRIP qRT-PCR), with validation by m 6 A inhibitors, DAA and SAH. m 6 A sites on CYP1A1 were identified by bioinformatics and luciferase assays, and CYP1A1 mRNA's interaction with IGF2BP3 was confirmed by RNA pull-down, luciferase, and RNA binding protein immunoprecipitation (RIP) assays.

RESULTS

N21aP was of the same environmental origin as benzo[a]pyrene (BaP) but was more stably present in the environment. N21aP could be metabolically activated by CYP1A1 to produce epoxides, causing DNA damage and further leading to lung inflammation. Importantly, in addition to the classical AhR pathway (i.e., BaP), N21aP also induced CYP1A1 expression with a posttranscriptional modification of m 6 A in CYP1A1 mRNA via the METTL14-IGF2BP3-CYP1A1 axis. Specifically, in the two recognition sites of METTL14 on the CYP1A1 mRNA transcript (position at 2700 and 5218), a methylation site (position at 5218) in the 3'-untranslated region (UTR) was recognized by IGF2BP3, enhanced the stability of CYP1A1 mRNA, and finally resulted in an increase in CYP1A1 expression.

DISCUSSION

This study systematically demonstrated that in addition to AhR-mediated transcriptional regulation, N21aP, had a new additional mechanism of m 6 A -mediated posttranscriptional modification, jointly contributing to CYP1A1 expression. Given that PAHs are the metabolic substrates of CYP1A1, this study not only helps to understand the significance of environment-genetic interactions for the toxicity of PAHs but also helps to better understand the health risks of the emerging PAHs at environmental exposure levels. https://doi.org/10.1289/EHP14055.

Autumn and spring observations of PM2.5-bound polycyclic aromatic hydrocarbons and nitro-polycyclic aromatic hydrocarbons in China and Japan

The transboundary transport of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) aggravated by the East Asian winter monsoon is a major atmospheric environmental issue in East Asia. To thoroughly elucidate the role of the East Asian monsoon on regional PAH and NPAH pollution in East Asia, PM2.5-bound PAHs and NPAHs were investigated concurrently at five sites in Beijing and Shenyang in China and Tsukuba, Kanazawa, and Wajima in Japan in autumn (November 2018) and spring (March 2019). During both autumn and spring sampling periods, the concentrations of PM2.5, PAHs, and NPAHs at sites in China were 1-2 orders of magnitude higher than those at sites in Japan, and showed an opposite temporal variation, with higher concentrations during the autumn sampling period due to intensive emissions and unfavourable weather conditions. During the sampling periods, PAHs at the Beijing and Shenyang sites had mixed sources of traffic emissions and coal and biomass combustion, while those at the Tsukuba, Kanazawa, and Wajima sites were mainly characterized by domestic traffic emissions. In addition, NPAHs at the five sites were jointly affected by primary combustion sources and atmospheric generation, with a greater contribution of atmospheric generation to the Beijing and Shenyang sites. Based on backwards trajectory clustering and concentration-weighted trajectory analysis, external contributions to PM2.5, PAHs, and NPAHs at each site were relatively stable during the two sampling periods, and potential source areas were mainly distributed in domestic cities and nearby sea areas. Therefore, the apparent temporal differences in the characteristics and sources of pollutants between sites in the two countries indicate that transboundary pollution dominated by the East Asian winter monsoon was unobvious in autumn and spring. The results of the study provide a time-specific solution for the effective management of regional air pollution during the East Asian winter monsoon.

Environmental surveillance in Jinan city of East China (2014-2022) reveals improved air quality but remained health risks attributable to PM2.5-bound metal contaminants

PM2.5-bound metal contaminants are associated with multiple chronic diseases in human. At global level, the contamination status has not been well controlled yet. Here we report findings from a long-term air pollution surveillance in Jinan city of Shandong, China. During 2014-2022, the dynamics and trends of PM2.5-bound heavy metal contaminants were monitored in an industrial area and a downtown area. The surveillance targets included: antimony (Sb), aluminum (Al), arsenic (As), beryllium (Be), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), manganese (Mn), nickel (Ni), selenium (Se). The human exposure and health risks were calculated and we found that the health risks of most contaminants showed peak values in autumn and winter. But Al, Mn, Hg and Be were found to result in highest health risk in spring or summer in the downtown area. In the industrial area we identified 100% alarming health index >1 (ranged from 1.12 to 3.35) in autumn and winter. In winter the total non-carcinogenic HI was all above 1 (peak value 2.21). Mn and As together posed >85% non-carcinogenic risk. As and Cd were ranked as major drivers of carcinogenic risks (5.84 × 10-6 and 2.78 × 10-6). Pd and Cd both showed non-negligible environmental levels but risk assessment model for their air-exposure associated non-carcinogenic risks are not yet available. This study updates air pollution data and status for air pollution status in China. This study provides valuable 9 year long-term reference to experimental and field studies in the related fields.

The role of N6-methyladenosine methylation in PAHs-induced cancers

Polycyclic aromatic hydrocarbons (PAHs), which are a wide range of environmental toxicants, may act on humans through inhalation, ingestion, and skin contact, resulting in a range of toxic reactions. Epidemiological studies showed that long-term exposure to PAHs in the occupational and living environment results in a substantial rise in the incidence rate of many cancers in the population, so the prevention and treatment of these diseases have become a major worldwide public health problem. N6-methyladenosine (m6A) modification greatly affects the metabolism of RNA and is implicated in the etiopathogenesis of many kinds of diseases. In addition, m6A-binding proteins have an important role in disease development. The abnormal expression of these can cause the malignant proliferation, migration, invasion, and metastasis of cancers. Furthermore, a growing number of studies revealed that environmental toxicants are one of the cancer risk factors and are related to m6A modifications. Exposure to environmental toxicants can alter the methylation level of m6A and the expression of the m6A-binding protein, thus promoting the occurrence and development of cancers through diverse mechanisms. m6A may serve as a biomarker for early environmental exposure. Through the study of m6A, we can find the health injury early, thus providing a new sight for preventing and curing environmental health-related diseases.

Long-term exposure to ambient fine particulate matter-bound polycyclic aromatic hydrocarbons and cancer mortality: A difference-in-differences approach

The association of ambient fine particulate matter (PM2.5) exposure with cancer mortality was controversial, which may ascribe to the difference in PM2.5 constituents. Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic constituents in PM2.5, which are suspected to account for PM2.5-induced cancer mortality but are yet to be investigated. We aimed to assess the association between long-term exposure to PM2.5-bound PAHs and cancer mortality and estimate the attributable mortality. A difference-in-differences approach was used to investigate the causal effect of long-term exposure to PM2.5-bound PAHs on cancer mortality. We divided Jiangsu province, China into 53 spatial units and summarized the annual number of cancer deaths in each spatial unit during 2016-2020. Annual population-weighted exposure to PM2.5-bound PAHs of each spatial unit was assessed by an inverse distance weighting method. The association between PM2.5-bound PAHs exposures and cancer mortality was evaluated by controlling spatial differences, temporal trends, PM2.5 mass exposures, temperatures, and socioeconomic status. Records of 793,269 cancer deaths were identified among 84.7 million population. Each ln-unit increase of exposure to total benzo[a]pyrene equivalents (∑BaPeq), total carcinogenic PAHs (∑PAH7c), and total PAHs (∑PAHs) was significantly associated with a 3.21%, 3.48%, and 2.64% increased risk of cancer mortality, respectively; the risk increased monotonically at low-level exposures but attenuated or flattened afterward (all p for nonlinearity <0.05). Similar exposure-response associations were identified for specific PAHs except that the associations for both fluoranthene and benzo[a]anthracene were linear. We estimated that exposure to ∑BaPeq, ∑PAH7c, and ∑PAHs contributed to 5.73%, 8.73%, and 7.33% of cancer deaths, respectively. In conclusion, long-term exposure to PM2.5-bound PAHs was associated with an increased risk of cancer mortality and contributed to substantial cancer deaths. Our findings highlight the importance to prevent deaths from cancer by reducing PM2.5-bound PAHs exposures and the necessity to take into consideration specific constituents in particulate pollution management in future.

Impact of social and economic factors on global thyroid cancer incidence and mortality

PURPOSE

The incidence of thyroid cancer has increased substantially over the past few decades and is partially explained by overdiagnosis. Geographical variations in incidence rates were reported to be related to national development status. This study aimed to gain deeper insights into global thyroid cancer burden by incorporating additional social and economic factors to account for cross-national disparities.

METHODS

We performed a multivariate analysis of age-standardized incidence and mortality data from the GLOBOCAN 2020 database for 126 countries that had more than 100 incident cases of thyroid cancer. The human development index (HDI), current health expenditure, and additional Global Health Observatory indicators were extracted from multiple sources.

RESULTS

Age-standardized incidence was highly correlated with HDI (standardized coefficient beta = 0.523, 95% confidence interval [CI] = 0.275-0.771) among the countries studied. The prevalence of raised fasting blood glucose was associated with age-standardized mortality (beta = 0.277, 95% CI = 0.038-0.517). Generally, the mortality-to-incidence ratio was higher in males than in females. In multivariate analysis, HDI (beta = - 0.767, 95% CI = - 0.902 to - 0.633), current health expenditure (beta = 0.265, 95% CI = 0.137-0.394), and fine particulate matter (PM2.5) concentrations (beta = 0.192, 95% CI = 0.086-0.298) were associated with mortality-to-incidence ratios.

CONCLUSIONS

National developments gauged by HDI explain the majority of the variation in incidence rates of thyroid cancer but play a smaller role in disparities in mortality rates. The association between air pollution and thyroid cancer outcomes warrants further investigation.

Long-Term Atmosphere Surveillance (2016-2021) of PM2.5-bound Polycyclic Aromatic Hydrocarbons and Health Risk Assessment in Yangtze River Delta, China

Long-term atmospheric quality monitoring of fine particulate matter (PM2.5) and PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) was performed in Wuxi from 2016 to 2021. In total, 504 atmospheric PM2.5 samples were collected, and PM2.5-bound 16 PAHs were detected. The PM2.5 and ∑PAHs level decreased annually from 2016 to 2021, from 64.3 to 34.0 μg/m3 and 5.27 to 4.22 ng/m3, respectively. The benzo[a]pyrene (BaP) levels of 42% of the monitoring days in 2017 exceeded the recommended European Union (EU) health-based standard of 1 ng/m3. Five- and six-ring PAHs were found, including benz[a]anthracene, benzo[k]fluoranthene (Bkf), BaP, and benzo[g,h,i]perylene, which were the dominant components (indicating a prominent petroleum, biomass, and coal combustion contribution) using molecular diagnostic ratios and positive matrix factorization analysis. Moreover, PM2.5 and PAHs were significantly negatively associated with local precipitation over a period of six years. Statistically significant temporal and spatial distribution differences of PM2.5, and ∑PAHs were also found. The toxicity equivalent quotient (TEQ) of total PAHs was 0.70, and the TEQ of BaP (0.178) was the highest, followed by that of Bkf (0.090), dibenz[a,h]anthracene (Dah) (0.048), and indeno[1,2,3-cd]pyrene (0.034). The medians of the incremental lifetime cancer risk for long-term exposure to PAHs were 2.74E-8, 1.98E-8, and 1.71E-7 for children, teenagers, and adults, respectively, indicating that the carcinogenic risk of PAHs pollution in air was acceptable to local residents in this area. Sensitivity analysis revealed that BaP, Bkf, and Dah significantly contributed to carcinogenic toxicity. This research provides comprehensive statistics on the local air persistent organic pollutants profile, helps to identify the principal pollution source and compounds, and contributes to the prevention of regional air pollution.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12403-023-00572-x.

Atmospheric PM2.5 induce autophagy and autophagic flux blockage in HUVEC cells via ROS/TXNIP signaling: Important role of metal components

Autophagy was involved in vascular endothelial injury caused by PM_2.5, which aggravated the pathogenesis of cardiovascular diseases. However, major toxic components and underlying mechanism responsible for PM_2.5-induced autophagy remain unclear. In this study, the effects of water-extracted PM_2.5 (WE-PM_2.5) on autophagy in human umbilical vein endothelial cells (HUVEC) were studied. Our results showed WE-PM_2.5 promoted autophagosome initiation and formation, meanwhile, lysosomal function was impaired, which further caused autophagic flux blockage in HUVEC cells. Furthermore, removal of metals alleviated WE-PM_2.5-induced autophagic flux blockage, while the artificial metal mixture reproduced the WE-PM_2.5 response. Mechanistically, ROS regulated autophagy-related proteins evidenced by BECN1, LC3B and p62 expression reversed by NAC pretreatment in WE-PM_2.5-exposed cells. WE-PM_2.5 also increased TXNIP expression mediated by ROS; moreover, knockdown of TXNIP in WE-PM_2.5-exposed cells decreased BECN1 and LC3B expression, but had little effects on the expression of p62, CTSB, and CTSD, indicating WE-PM_2.5-induced TXNIP was involved in autophagosome initiation and formation rather than autophagic degradation. Collectively, WE-PM_2.5-induced ROS not only promoted autophagosome initiation and formation, but also inhibited autophagic degradation. However, as the downstream molecule of ROS, TXNIP was only involved in autophagosome initiation and formation. Importantly, WE-PM_2.5-bound metals were largely responsible for autophagic flux blockage in HUVEC cells.

Socioeconomic disparity in the association between fine particulate matter exposure and papillary thyroid cancer

BACKGROUND

Limited data exists suggesting that cumulative exposure to air pollution in the form of fine particulate matter (aerodynamic diameter ≤ 2.5 μm [PM2.5]) may be associated with papillary thyroid carcinoma (PTC), although this relationship has not been widely established. This study aims to evaluate the association between PM2.5 and PTC and determine the subgroups of patients who are at the highest risk of PTC diagnosis.

METHODS

Under IRB approval, we conducted a case-control study of adult patients (age ≥ 18) newly diagnosed with PTC between 1/2013-12/2016 across a single health care system were identified using electronic medical records. These patients were compared to a control group of patients without any evidence of thyroid disease. Cumulative PM2.5 exposure was calculated for each patient using a deep learning neural networks model, which incorporated meteorological and satellite-based measurements at the patients' residential zip code. Adjusted multivariate logistic regression was used to quantify the association between cumulative PM2.5 exposure and PTC diagnosis. We tested whether this association differed by gender, race, BMI, smoking history, current alcohol use, and median household income.

RESULTS

A cohort of 1990 patients with PTC and a control group of 6919 patients without thyroid disease were identified. Compared to the control group, patients with PTC were more likely to be older (51.2 vs. 48.8 years), female (75.5% vs 46.8%), White (75.2% vs. 61.6%), and never smokers (71.1% vs. 58.4%) (p < 0.001). After adjusting for age, sex, race, BMI, current alcohol use, median household income, current smoking status, hypertension, diabetes, COPD, and asthma, 3-year cumulative PM2.5 exposure was associated with a 1.41-fold increased odds of PTC diagnosis (95%CI: 1.23-1.62). This association varied by median household income (p-interaction =0.03). Compared to those with a median annual household income <$50,000, patients with a median annual household income between $50,000 and < $100,000 had a 43% increased risk of PTC diagnosis (aOR = 1.43, 95%CI: 1.19-1.72), and patients with median household income ≥$100,000 had a 77% increased risk of PTC diagnosis (aOR = 1.77, 95%CI: 1.37-2.29).

CONCLUSIONS

Cumulative exposure to PM2.5 over 3 years was significantly associated with the diagnosis of PTC. This association was most pronounced in those with a high median household income, suggesting a difference in access to care among socioeconomic groups.

Di-(2-ethylhexyl) phthalate aggravates fine particulate matter-induced asthma in weanling mice due to T follicular helper cell-dependent response

Environmental pollutants fine particulate matter and di-(2-ethylhexyl) phthalate (DEHP) are believed to be the risk factors for childhood asthma. Allergic asthma is basically an immediate hypersensitivity mediated by IgE, the product of humoral immune response. T follicular helper cells (Tfh) have been newly identified as the crucial T helper cells for supporting B cells to produce immunoglobulins in humoral immunity. Tfh cells are therefore potentially to serve as the diagnostic marker and therapeutic target of immune diseases. In this study, we examined the joint effects of fine particulate matter and DEHP on the initiation and progression of asthma and explored the fundamental role of Tfh cells during the process. Weanling C57BL/6 mice (both sexes) were concurrently exposed to DEHP (intragastric administration at 300 μg/kg) and fine atmospheric particulate matter (mean particle diameter < 4 µm, PM4) (oropharyngeal instillation at 2 mg/kg) once every three days for 30 days (10 times). We found that DEHP displayed adjuvant effects to potentiate PM4 allergen-induced expansion of Tfh and plasma cells, production of serum IgE and IgG1, and occurrence of airway hyper-responsiveness and inflammation. Then PM4 and DEHP co-exposure was performed to Cd4 knock-out mice reconstituted with normal wild-type adoptive Tfh cells or non-Tfh cells. The results of immune adoptive transfusion indicated that the joint immunotoxic effects of PM4 and DEHP were dependent on Tfh cells. We further proved that DEHP could adjuvantly boost PM4-induced expression of BCL-6 and c-MAF and secretion of IL-13 and IL-4 in Tfh cells. In conclusion, these data suggest that DEHP metabolites act in an adjuvant-like manner to aggravate PM4 allergen-induced asthma based on anaphylactic IgE response, resulting from excessive IL-13 and IL-4 synthesized by abnormally differentiated Tfh cells.

Probiotics ameliorates pulmonary inflammation via modulating gut microbiota and rectifying Th17/Treg imbalance in a rat model of PM2.5 induced lung injury

The imbalance of intestinal microbiota and inflammatory response is crucial in the development of lung injury induced by PM2.5. In recent years, probiotics have attracted great attention for their health benefits in inflammatory diseases and regulating intestinal balance, but their intricate mechanisms need further experiments to elucidate. In our research, a rat lung damage model induced by PM2.5 exposure in real environment was established to explore the protective properties of probiotics on PM2.5 exposure injury and its related mechanism. The results indicated that compared with the AF control group, rats in the PM2.5 group gained weight slowly, ate less and had yellow hair. The results of pathological and immunohistochemical examinations showed that the inflammatory infiltration of lung tissue was alleviated after probiotic treatment. The Lung function results also showed the improvement effects of probiotics administration. In addition, probiotics could promote the balance of Th17 and Treg cells, inhibit cytokines expression (TNF-α, IL-6, IL-1β, IL-17A), and increase the concentration of anti-inflammatory factors (IL-10, TGF-β). In addition, 16 S rRNA sequence analysis showed that probiotic treatment could reduce microbiota abundance and diversity, increase the abundance of possible beneficial bacteria, and decrease the abundance of bacteria associated with inflammation. In general, probiotic intervention was found to have preventive effects on the occurrence of PM2.5 induced pathological injury, and the mechanism was associate with to the inhibition of inflammatory response, regulation of Th17/Treg balance and maintenance of intestinal internal environment stability.