Exposure to air pollution interacts with obesogenic nutrition to induce tissue-specific response patterns

Air Pollution in Cardio-Oncology and Unraveling the Environmental Nexus: JACC: CardioOncology State-of-the-Art Review

Although recent advancements in cancer therapies have extended the lifespan of patients with cancer, they have also introduced new challenges, including chronic health issues such as cardiovascular disease arising from pre-existing risk factors or cancer therapies. Consequently, cardiovascular disease has become a leading cause of non-cancer-related death among cancer patients, driving the rapid evolution of the cardio-oncology field. Environmental factors, particularly air pollution, significantly contribute to deaths associated with cardiovascular disease and specific cancers, such as lung cancer. Despite these statistics, the health impact of air pollution in the context of cardio-oncology has been largely overlooked in patient care and research. Notably, the impact of air pollution varies widely across geographic areas and among individuals, leading to diverse exposure consequences. This review aims to consolidate epidemiologic and preclinical evidence linking air pollution to cardio-oncology while also exploring associated health disparities and environmental justice issues.

Toxicity mechanisms of biomass burning aerosols in in vitro hepatic steatosis models

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that contributes to the global rise in liver-related morbidity and mortality. Wood tar (WT) aerosols are a significant fraction of carbonaceous aerosol originating from biomass smoldering, contributing to air pollution particles smaller than 2.5 mm (PM2.5). Mechanistic biological associations exist between exposure to PM2.5 and increased NAFLD phenotypes in both cell and animal models. Therefore, this study examines whether an existing NAFLD-like condition can enhance the biological susceptibility of liver cells exposed to air pollution in the form of WT material. Liver cells were incubated with lauric or oleic acid (LA, OA, respectively) for 24 h to accumulate lipids and served as an in vitro hepatic steatosis model. When exposed to 0.02 or 0.2 g/L water-soluble WT aerosols, both steatosis model cells showed increased cell death compared to the control cells (blank-treated cells with or without pre-incubation with LA or OA) or compared to WT-treated cells without pre-incubation with LA or OA. Furthermore, alterations in oxidative status included variations in reactive oxygen species (ROS) levels, elevated levels of lipid peroxidation adducts, and decreased expression of antioxidant genes associated with the NRF2 transcription factor. In addition, steatosis model cells exposed to WT had a higher degree of DNA damage than the control cells (blank-treated cells with or without pre-incubation with LA or OA). These results support a possible systemic effect through the direct inflammatory and oxidative stress response following exposure to water-soluble WT on liver cells, especially those predisposed to fatty liver. Furthermore, the liver steatosis model can be influenced by the type of fatty acid used; increased adverse effects of WT on metabolic dysregulation were observed in the LA model to a higher extent compared to the OA model.

Sub-toxic events induced by truck speed-facilitated PM2.5 and its counteraction by epigallocatechin-3-gallate in A549 human lung cells

To distinguish the influences of fuel type and truck speed on chemical composition and sub-toxic effects of particulates (PM2.5) from engine emissions, biomarkers-interleukin-6 (IL-6), cytochrome P450 (CYP) 1A1, heme oxygenase (HO)-1, and NADPH-quinone oxidoreductase (NQO)-1-were studied in A549 human lung cells. Fuel type and truck speed preferentially affected the quantity and ion/polycyclic aromatic hydrocarbon (PAH) composition of PM2.5, respectively. Under idling operation, phenanthrene was the most abundant PAH. At high speed, more than 50% of the PAHs had high molecular weight (HMW), of which benzo[a]pyrene (B[a]P), benzo[ghi]perylene (B[ghi]P), and indeno[1,2,3-cd]pyrene (I[cd]P) were the main PAHs. B[a]P, B[ghi]P, and I[cd]P caused potent induction of IL-6, CYP1A1, and NQO-1, whereas phenanthrene mildly induced CYP1A1. Based on the PAH-mediated induction, the predicted increases in biomarkers were positively correlated with the measured increases. HMW-PAHs contribute to the biomarker induction by PM2.5, at high speed, which was reduced by co-exposure to epigallocatechin-3-gallate.

Global association between atmospheric particulate matter and obesity: A systematic review and meta-analysis

BACKGROUND

Among various air pollutants, particulate matter (PM) is the most harmful and representative pollutant. Although several studies have shown a link between particulate pollution and obesity, the conclusions are still inconsistent.

METHODS

We conducted a systematic review and meta-analysis to pool the effect of PM exposure on obesity. Five databases (including PubMed, Web of Science, Scopus, Embase, and Cochrane) were searched for relevant studies up to Jan 2022. Adjusted risk ratio (RR) with corresponding 95% confidence interval (CI) were retrieved from individual studies and pooled with random effect models by STATA software. Besides, we tested the stability of results by Egger's test, Begg's test, funnel plot, and using the trim-and-fill method to modify the possible asymmetric funnel graph. The NTP-OHAT guidelines were followed to assess the risk of bias. Then the GRADE was used to evaluate the certainty of evidence.

RESULTS

26 studies were included in this meta-analysis. 19 studies have shown that PM_2.5 can increase the risk of obesity per 10 μg/m³ increment (RR: 1.159, 95% CI: 1.111-1.209), while 15 studies have indicated that PM₁₀ increase the risk of obesity per 10 μg/m³ increment (RR: 1.092, 95% CI: 1.070-1.116). Besides, 5 other articles with maternal exposure showed that PM_2.5 increases the risk of obesity in children (RR: 1.06, 95% CI: 1.02-1.11). And we explored the source of heterogeneity by subgroup analysis, which suggested associations between PM and obesity tended to vary by region, age group, participants number, etc. The analysis results showed publication bias and other biases are well controlled, but most certainties of the evidence were low, and more research is required to reduce these uncertainties.

CONCLUSION

Exposure to PM_2.5 and PM₁₀ with per 10 μg/m³ increment could increase the risk of obesity in the global population.

Urban-rural differences in the association between long-term exposure to ambient air pollution and obesity in China

INTRODUCTION

Ambient air pollution might increase the risk of obesity; however, the evidence regarding the relationship between air pollution and obesity in comparable urban and rural areas is limited. Therefore, our aim was to contrast the effect estimates of varying air pollution particulate matter on obesity between urban and rural areas.

METHODS

Four obesity indicators were evaluated in this study, namely, body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR). Exposure to ambient air pollution (e.g., particulate matter with aerodynamic diameters 1.0 μm [PM₁], PM_2.5, and PM₁₀) was estimated using satellite-based random forest models. Linear regression and logistic regression models were used to assess the associations between air pollution particulate matter and obesity. Furthermore, the effect estimates of different air pollution particulates were contrasted between urban and rural areas.

RESULTS

A total of 36,998 participants in urban areas and 31, 256 in rural areas were included. We found positive associations between long-term exposure to PM₁, PM_2.5, and PM₁₀ and obesity. Of these air pollutants, PM_2.5 had the strongest association. The results showed that the odds ratios (ORs) for general obesity were 1.8 (95% CI, 1.64 to 1.98) per interquartile range (IQR) μg/m³ increase in PM₁, 1.89 (95% CI, 1.71 to 2.1) per IQR μg/m³ increase in PM_2.5, and 1.74 (95% CI, 1.58 to 1.9) per IQR μg/m³ increase in PM₁₀. The concentrations of air pollutants were lower in rural areas, but the effects of air pollution on obesity of rural residents were higher than those of urban residents.

CONCLUSION

Long-term (3 years average) exposure to ambient air pollution was associated with an increased risk of obesity. We observed regional disparities in the effects of particulate matter exposure from air pollution on the risk of obesity, with higher effect estimates found in rural areas. Air quality interventions should be prioritized not only in urban areas but also in rural areas to reduce the risk of obesity.

Association between ambient particulate matter exposure and metabolic syndrome risk: A systematic review and meta-analysis

Although the association between ambient particulate matter and metabolic syndrome (MetS) has been investigated, the effect of particulate matter (PM) on MetS is inconclusive. We conducted a systematic review and meta-analysis to study the association between long-term ambient PM exposure and MetS risk. The data from five databases were extracted to analyze the association between ambient PM exposure and MetS risk. A random-effects model was performed to estimate the overall risk effect. The present systematic review and meta-analysis illustrated that an increase of 5 μg/m³ in annual PM_2.5 or PM₁₀ concentration was associated with 14% or 9% increases of MetS risk, respectively (PM_2.5, RR = 1.14, 95%CI [1.03, 1.25]; PM₁₀, RR = 1.09, 95%CI [1.00, 1.19]). The population-attributable risk (PAR) was 12.28% for PM_2.5 exposure or 8.26% for PM₁₀ exposure, respectively. There was statistical association between PM_2.5 exposure and risk of MetS in male proportion ≥50%, Asia, related disease or medication non-adjustment subgroup as well as cohort study subgroups, respectively. The significant association between PM₁₀ exposure and risk of MetS was observed in male proportion ≥50% and calories intake adjustment subgroups, respectively. Sensitivity analyses showed the robustness of our results. No publication bias was detected. In conclusion, there was positive association between long-term PM exposure and MetS risk. 12.28% of MetS risk could be attributable to PM_2.5 exposure.

Dysregulation of autophagy acts as a pathogenic mechanism of non-alcoholic fatty liver disease (NAFLD) induced by common environmental pollutants

Non-alcoholic fatty liver disease (NAFLD) has been the most common chronic liver disease in the world, including the developing countries. NAFLD is metabolic disease with significant lipid deposition in the hepatocytes of the liver, which is usually associated with oxidative stress, inflammation and fibrogenesis, and insulin resistance. Progressive NAFLD can develop into non-alcoholic steatohepatitis (NASH) or hepatocellular carcinoma. The current evidence proposes that environmental pollutants promote development and progression of NAFLD, and autophagy plays a vital role but is multifactorial affected in NAFLD. In this review, we analyzed on the regulations of common environmental pollutants on autophagy in NAFLD. To clarify the involved roles of autophagy, we discussed the dysregulation of autophagy by environmental pollutants in adipose tissue and gut, and their interactions with liver, as well as epigenetic regulation on autophagy by environmental pollutants. Furthermore, protective roles of potential therapeutic treatments on the multiple-hits of autophagy in NAFLD were descripted.

Exposure to pollutants altered glucocorticoid signaling and clock gene expression in female mice. Evidence of tissue- and sex-specificity

Environmental pollutants suspected of disrupting the endocrine system are considered etiologic factors in the epidemic of metabolic disorders. As regulation of energy metabolism relies on the integrated action of a large number of hormones, we hypothesized that certain chemicals could trigger changes in glucocorticoid signaling. To this end, we exposed C57Bl6/J female and male mice between 5 and 20 weeks of age to a mixture of 2,3,7,8- tetrachlorodibenzo-p-dioxin (20 pg/kg body weight/day [bw/d]), polychlorobiphenyl 153 (200 ng/kg bw/d), di-[2-ethylhexyl]-phthalate (500 μg/kg bw/d) and bisphenol A (40 μg/kg bw/d). In female mice fed a standard diet (ST), we observed a decrease in plasma levels of leptin as well as a reduced expression of corticoid receptors Nr3c1 and Nr3c2, of leptin and of various canonical genes related to the circadian clock machinery in visceral (VAT) but not subcutaneous (SAT) adipose tissue. However, Nr3c1 and Nr3c2 mRNA levels did not change in high-fat-fed females exposed to pollutants. In ST-fed males, pollutants caused the same decrease of Nr3c1 mRNA levels in VAT observed in ST-fed females but levels of Nr3c2 and other clock-related genes found to be down-regulated in female VAT were enhanced in male SAT and not affected in male VAT. The expression of corticoid receptors was not affected in the livers of both sexes in response to pollutants. In summary, exposure to a mixture of pollutants at doses lower than the no-observed adverse effect levels (NoAELs) resulted in sex-dependent glucocorticoid signaling disturbances and clock-related gene expression modifications in the adipose tissue of ST-fed mice.

Epigenetic signatures underlying inflammation: an interplay of nutrition, physical activity, metabolic diseases, and environmental factors for personalized nutrition

AIM AND OBJECTIVE

Emerging translational evidence suggests that epigenetic alterations (DNA methylation, miRNA expression, and histone modifications) occur after external stimuli and may contribute to exacerbated inflammation and the risk of suffering several diseases including diabetes, cardiovascular diseases, cancer, and neurological disorders. This review summarizes the current knowledge about the harmful effects of high-fat/high-sugar diets, micronutrient deficiencies (folate, manganese, and carotenoids), obesity and associated complications, bacterial/viral infections, smoking, excessive alcohol consumption, sleep deprivation, chronic stress, air pollution, and chemical exposure on inflammation through epigenetic mechanisms. Additionally, the epigenetic phenomena underlying the anti-inflammatory potential of caloric restriction, n-3 PUFA, Mediterranean diet, vitamin D, zinc, polyphenols (i.e., resveratrol, gallic acid, epicatechin, luteolin, curcumin), and the role of systematic exercise are discussed.

METHODS

Original and review articles encompassing epigenetics and inflammation were screened from major databases (including PubMed, Medline, Science Direct, Scopus, etc.) and analyzed for the writing of the review paper.

CONCLUSION

Although caution should be exercised, research on epigenetic mechanisms is contributing to understand pathological processes involving inflammatory responses, the prediction of disease risk based on the epigenotype, as well as the putative design of therapeutic interventions targeting the epigenome.

Diets enriched with coconut, fish, or olive oil modify peripheral metabolic effects of ozone in rats

Dietary factors may modulate metabolic effects of air pollutant exposures. We hypothesized that diets enriched with coconut oil (CO), fish oil (FO), or olive oil (OO) would alter ozone-induced metabolic responses. Male Wistar-Kyoto rats (1-month-old) were fed normal diet (ND), or CO-, FO-, or OO-enriched diets. After eight weeks, animals were exposed to air or 0.8 ppm ozone, 4 h/day for 2 days. Relative to ND, CO- and OO-enriched diet increased body fat, serum triglycerides, cholesterols, and leptin, while all supplements increased liver lipid staining (OO > FO > CO). FO increased n-3, OO increased n-6/n-9, and all supplements increased saturated fatty-acids. Ozone increased total cholesterol, low-density lipoprotein, branched-chain amino acids (BCAA), induced hyperglycemia, glucose intolerance, and changed gene expression involved in energy metabolism in adipose and muscle tissue in rats fed ND. Ozone-induced glucose intolerance was exacerbated by OO-enriched diet. Ozone increased leptin in CO- and FO-enriched groups; however, BCAA increases were blunted by FO and OO. Ozone-induced inhibition of liver cholesterol biosynthesis genes in ND-fed rats was not evident in enriched dietary groups; however, genes involved in energy metabolism and glucose transport were increased in rats fed FO and OO-enriched diet. FO- and OO-enriched diets blunted ozone-induced inhibition of genes involved in adipose tissue glucose uptake and cholesterol synthesis, but exacerbated genes involved in adipose lipolysis. Ozone-induced decreases in muscle energy metabolism genes were similar in all dietary groups. In conclusion, CO-, FO-, and OO-enriched diets modified ozone-induced metabolic changes in a diet-specific manner, which could contribute to altered peripheral energy homeostasis.

Particulate Matter Toxicity Is Nrf2 and Mitochondria Dependent: The Roles of Metals and Polycyclic Aromatic Hydrocarbons

Particulate matter (PM), an important component of air pollution, induces significant adverse health effects. Many of the observed health effects caused by inhaled PM are associated with oxidative stress and inflammation. This association has been linked in particular to the particles’ chemical components, especially the inorganic/metal and the organic/polycyclic aromatic hydrocarbon (PAH) fractions, and their ability to generate reactive oxygen species in biological systems. The transcription factor NF-E2 nuclear factor erythroid-related factor 2 (Nrf2) is activated by redox imbalance and regulates the expression of phase II detoxifying enzymes. Nrf2 plays a key role in preventing PM-induced toxicity by protecting against oxidative damage and inflammation. This review focuses on specific PM fractions, particularly the dissolved metals and PAH fractions, and their roles in inducing oxidative stress and inflammation in cell and animal models with respect to Nrf2 and mitochondria.

Interactions between ambient air pollution and obesity on lung function in children: The Seven Northeastern Chinese Cities (SNEC) Study

Children are vulnerable to air pollution-induced lung function deficits, and the prevalence of obesity has been increasing in children. To evaluate the joint effects of long-term PM₁ (particulate matter with an aerodynamic diameter ≤ 1.0 μm) exposure and obesity on children's lung function, a cross-sectional sample of 6740 children (aged 7-14 years) was enrolled across seven northeastern Chinese cities from 2012 to 2013. Weight and lung function, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV₁), peak expiratory flow (PEF), and maximal mid-expiratory flow (MMEF), were measured according to standardized protocols. Average PM₁, PM_2.5, PM₁₀ and nitrogen dioxide (NO₂) exposure levels were estimated using a spatiotemporal model, and sulphur dioxide (SO₂) and ozone (O₃) exposure were estimated using data from municipal air monitoring stations. Two-level logistic regression and general linear models were used to analyze the joint effects of body mass index (BMI) and air pollutants. The results showed that long-term air pollution exposure was associated with lung function impairment and there were significant interactions with BMI. Associations were stronger among obese and overweight than normal weight participants (the adjusted odds ratios (95% confidence intervals) for PM₁ and lung function impairments in three increasing BMI categories were 1.50 (1.07-2.11) to 2.55 (1.59-4.07) for FVC < 85% predicted, 1.44 (1.03-2.01) to 2.51 (1.53-4.11) for FEV₁ < 85% predicted, 1.34 (0.97-1.84) to 2.04 (1.24-3.35) for PEF < 75% predicted, and 1.34 (1.01-1.78) to 1.93 (1.26-2.95) for MMEF < 75% predicted). Consistent results were detected in linear regression models for PM₁, PM_2.5 and SO₂ on FVC and FEV₁ impairments (P_Interaction < 0.05). These modification effects were stronger among females and older participants. These results can provide policy makers with more comprehensive information for to develop strategies for preventing air pollution induced children's lung function deficits among children.

Metabolic profiling of liver tissues in mice after instillation of fine particulate matter

Human exposure to fine particulate matter (PM_2.5) in various environment could lead to a number of adverse health effects. Little is known about the toxic mechanism and the further response caused by PM_2.5 exposure. In this study, a metabolomics approach using gas chromatography-mass spectrometry (GC-MS) was adopted to evaluate the liver toxicity induced by different gradient concentrations of PM_2.5. A multivariate statistical analysis had shown, a total of 12 endogenous metabolites including amino acids and organic acids were identified as potential biomarkers of PM_2.5 and most of them were down-regulated. By analyzing the metabolic pathways using the identified biomarkers, the significantly interfered metabolic pathways when mice were exposed to PM_2.5 were found as: glycine, serine and threonine metabolism, aminoacyl-tRNA biosynthesis, cysteine and methionine metabolism, alanine, aspartate and glutamate metabolism, methane metabolism, linoleic acid metabolism and valine, and leucine and isoleucine biosynthesis, all of which were closely related to liver metabolism. The findings of this study reveal detailed toxic metabolic effects of PM_2.5 in liver tissues, provide ways for assessing the health risk of PM_2.5 at molecular level, and further offer insights on the potential mechanism of its toxicity.

Neuroendocrine Regulation of Air Pollution Health Effects: Emerging Insights

Air pollutant exposures are linked to cardiopulmonary diseases, diabetes, metabolic syndrome, neurobehavioral conditions, and reproductive abnormalities. Significant effort is invested in understanding how pollutants encountered by the lung might induce effects in distant organs. The role of circulating mediators has been predicted; however, their origin and identity have not been confirmed. New evidence has emerged which implicates the role of neuroendocrine sympathetic-adrenal-medullary (SAM) and hypothalamic-pituitary-adrenal (HPA) stress axes in mediating a wide array of systemic and pulmonary effects. Our recent studies using ozone exposure as a prototypical air pollutant demonstrate that increases in circulating adrenal-derived stress hormones (epinephrine and cortisol/corticosterone) contribute to lung injury/inflammation and metabolic effects in the liver, pancreas, adipose, and muscle tissues. When stress hormones are depleted by adrenalectomy in rats, most ozone effects including lung injury/inflammation are diminished. Animals treated with antagonists for adrenergic and glucocorticoid receptors show inhibition of the pulmonary and systemic effects of ozone, whereas treatment with agonists restore and exacerbate the ozone-induced injury/inflammation phenotype, implying the role of neuroendocrine activation. The neuroendocrine system is critical for normal homeostasis and allostatic activation; however, chronic exposure to stressors may lead to increases in allostatic load. The emerging mechanisms by which circulating mediators are released and are responsible for producing multiorgan effects of air pollutants insists upon a paradigm shift in the field of air pollution and health. Moreover, since these neuroendocrine responses are linked to both chemical and nonchemical stressors, the interactive influence of air pollutants, lifestyle, and environmental factors requires further study.

Ambient air pollution exposure and obesity-related traits in Korean adults

PURPOSE

Although some studies have tried to determine the impact of long-term air pollution exposure on obesity, they have mainly focused on body mass index (BMI) and the results are inconsistent. Therefore, we investigated the association of annual ambient air pollution exposure with various obesity traits, including computed tomography-measured abdominal fatness, in a large Korean adult population.

PATIENTS AND METHODS

A total of 5,114 participants who underwent routine health check-ups at Seoul National University Hospital were included in the analysis. We calculated the annual average concentrations of ambient air pollutants, such as particulate matter ≤10 μm in diameter (PM₁₀) and nitrogen dioxide (NO₂), using the individual's zip code. Obesity-related indicators included the BMI, waist circumference (WC), percent body fat (PBF), total adipose tissue (TAT), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT).

RESULTS

The mean age of the population was 53.5 and 70.9% were men. The mean annual concentrations of PM₁₀ and NO₂ were 49.4 μg/m³ and 30.3 ppb, respectively. In the full covariates model, adjusted for demographic and clinical variables, interquartile range increase in annual average concentration of PM₁₀ and NO₂ was not associated with any obesity-related phenotypes including BMI, WC, PBF, TAT, VAT, and SAT (all P>0.05). Likewise, no significant association between air pollutants and obesity-related traits was observed in any subgroups, stratified by sex and age (all P>0.05).

CONCLUSION

Annual exposure to ambient air pollution is not associated with any obesity-related traits in Korean adults.

DNA methylation: A critical epigenetic mechanism underlying the detrimental effects of airborne particulate matter

Exposure to airborne particulate matter (PM) does great harm to the health of human beings. To date, PM exposure has been closely associated with respiratory and cardiovascular diseases, as well as some types of cancer. As the associations of PM with the adverse health effects are well documented in literatures, the underlying mechanisms have not been completely clarified. With the field of epigenetics rising in recent years, PM-associated epigenetic alterations have gradually turned into the hot research topic. DNA methylation is one of the earliest-discovered and best-studied epigenetic mechanisms, of which the alteration can influence the transcription initiation of genes. A number of studies have been published to demonstrate that PM exposure is linked with DNA methylation patterns in the human genome. DNA methylation is the potential regulator of the biological effects of PM exposure. In the present review, DNA methylation related to PM exposure was elaborated on genome-wide and gene-specific methylation. In particular, genome-wide DNA methylation was composed of the alterations in global methylation content and genome-wide methylation profile; gene-specific methylation included the methylation changes in mechanism-related and disease-specific genes. Representative epidemiological and experimental studies were cited to elucidate the viewpoints, focusing on both PM-related methylation changes and the mediating effects of DNA methylation between PM and the health impacts. This review will provide advantageous clues for subsequent studies on the DNA methylation in relation to PM exposure.