Interaction effects of long-term air pollution exposure and variants in the GSTP1, GSTT1 and GSTCD genes on risk of acute myocardial infarction and hypertension: a case-control study

A genome-wide by PM10 exposure interaction study for blood pressure in Korean adults

Blood pressure (BP) is a typical complex trait, and the genetic susceptibility of individuals to changes in BP induced by air pollution exposure is different. Although interactions of exposure to air pollutants with several candidate genes have been identified, genome-wide interaction studies (GWISs) are needed to understand the association between them with BP. Therefore, we aimed to discover the unique genetic loci for BP that interact with exposure to air pollutants in Korean adults. We ultimately included 1868 participants in the discovery step and classified them into groups of those with low-to-moderate exposure and high exposure to average annual concentration of particulate matter with an aerodynamic diameter ≤ 10 μm (PM10). Because none of the single nucleotide polymorphisms (SNPs) achieved a genome-wide level of significance of pint < 5 × 10-8 for either systolic BP (SBP) or diastolic BP (DBP), we considered the top 10 ranking SNPs for each BP trait. To validate these suggestive SNPs, we finally selected six genetic variants for SBP and five variants for DBP, respectively. In a replication result for SBP, only one SNP (rs12914147) located in an intergenic region of the NR2F2 showed a significant interaction. We also identified several genetic susceptibility loci (e.g., CHST11, TEK, and ITGA1) implicated in candidate mechanisms such as inflammation and oxidative stress in the discovery step, although their interaction effects were not replicated. Our study reports the first GWIS finding to our knowledge, and the association between exposure to PM10 and BP levels may be determined in part by several newly discovered genetic suggestive loci, including NR2F2.

Ambient Air Pollution and All-Cause and Cause-Specific Mortality in an Analysis of Asian Cohorts

INTRODUCTION

Much of what is currently known about the adverse effects of ambient air pollution comes from studies conducted in high-income regions, with relatively low air pollution levels. The aim of the current project is to examine the relationship between exposure to ambient air pollution (as predicted from satellite-based models) and all-cause and cause-specific mortality in several Asian cohorts.

METHODS

Cohorts were recruited from the Asia Cohort Consortium (ACC). The geocoded residences of participants were assigned levels of ambient particulate material with aerodynamic diameter of 2.5 μm or less (PM2.5) and nitrogen dioxide (NO2) utilizing global satellite-derived models and assigned for the year of enrollment (or closest available year). The association between ambient exposure and mortality was established with Cox proportional hazard models, after adjustment for common confounders. Both single- and two-pollutant models were generated. Model robustness was evaluated, and hazard ratios were calculated for each cohort separately and combined via random effect meta-analysis for pooled risk estimates.

RESULTS

Six cohort studies from the ACC participated: the Community-based Cancer Screening Program (CBCSCP, Taiwan), the Golestan Cohort Study (Iran), the Health Effects for Arsenic Longitudinal Study (HEALS, Bangladesh), the Japan Public Health Center-based Prospective Study (JPHC), the Korean Multi-center Cancer Cohort Study (KMCC), and the Mumbai Cohort Study (MCS, India). The cohorts represented over 340,000 participants.

Mean exposures to PM2.5 ranged from 8 to 58 μg/m3. Mean exposures to NO2 ranged from 7 to 23 ppb. For PM2.5, a positive, borderline nonsignificant relationship was observed between PM2.5 and cardiovascular mortality. Other relationships with PM2.5 tended toward the null in meta-analysis. For NO2, an overall positive relationship was observed between exposure to NO2 and all cancers and lung cancer. A borderline association between NO2 and nonmalignant lung disease was also observed. The findings within individual cohorts remained consistent across a variety of subgroups and alternative analyses, including two-pollutant models.

CONCLUSIONS

In a pooled examination of cohort studies across Asia, ambient PM2.5 exposure appears to be associated with an increased risk of cardiovascular mortality and ambient NO2 exposure is associated with an increased cancer (and lung cancer) mortality. This project has shown that satellite-derived models of pollution can be used in examinations of mortality risk in areas with either incomplete or missing air pollution monitoring.

Genetic risk modifies the effect of long-term fine particulate matter exposure on coronary artery disease

BACKGROUND

Although both environmental and genetic factors were linked to coronary artery disease (CAD), the extent to which the association of air pollution exposure with CAD can be influenced by genetic risk was not well understood.

METHODS

A total of 41,149 participants recruited from the project of Prediction for Atherosclerotic Cardiovascular Disease Risk in China (China-PAR) were included. Genetic risk scores of CAD were constructed based on 540 genetic variants. Long-term PM_2.5 exposures were assessed by adopting satellite-based PM_2.5 estimations at 1-km resolution. We used stratified Cox proportional hazards regression model to examine the impact of PM_2.5 exposure and genetic risk on CAD risk, and further analyzed modification effect of genetic predisposition on association between PM_2.5 exposure and CAD risk.

RESULTS

During a median of 13.01 years of follow-up, 1,373 incident CAD events were observed. Long-term PM_2.5 exposure significantly increased CAD risk, and the hazard ratios (HRs) [95% confidence intervals (CIs)] were 1.27 (1.05-1.54) and 1.95 (1.57-2.42) among intermediate and high PM_2.5 exposure groups compared to low PM_2.5 exposure group. The relative risks of CAD were 40% (HR: 1.40, 95%CI: 1.18-1.66) and 133% (HR: 2.33, 95%CI: 1.94-2.79) higher among individuals at intermediate and high genetic risk than those at low genetic risk. Compared with individuals with both low genetic risk and low PM_2.5 exposure, those with high genetic risk and high PM_2.5 exposure had highest CAD risk, with HR of 4.37 (95%CI: 3.13-6.11). We observed significant multiplicative (P < 0.001) and additive interaction [relative excess risk due to interaction (95%CI): 2.75 (1.32-4.20); attributable proportion due to interaction (95%CI): 0.56 (0.42-0.70)] between genetic risk and PM_2.5 exposure on CAD.

CONCLUSION

This study provided evidence that long-term PM_2.5 exposure might increase CAD risk, especially among people at high genetic risk. Our findings highlighted the importance of taking strategies on air quality improvement to cardiovascular disease prevention.

Subclinical cardiovascular outcomes of acute exposure to fine particulate matter and its constituents: A glutathione S-transferase polymorphism-based longitudinal study

To explore the acute subclinical cardiovascular effects of fine particulate matter (PM_2.5) and its constituents, a longitudinal study with 61 healthy young volunteers was conducted in Xinxiang, China. Linear mixed-effect models were used to analyze the association of PM_2.5 and its constituents with cardiovascular outcomes, respectively, including blood pressure (BP), heart rate (HR), serum levels of high-sensitivity C-reactive protein (hs-CRP), 8-hydroxy-2'-deoxyguanosine (8-OHdG), tissue-type plasminogen activator (t-PA), and platelet-monocyte aggregation (PMA). Additionally, the modifying effects of glutathione S-transferase mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1) polymorphisms were examined. A 10 μg/m³ increase in PM_2.5 was associated with -1.04 (95 % CI: -1.86 to -0.22) mmHg and -0.90 (95 % CI: -1.69 to -0.11) mmHg decreases in diastolic BP (DBP) and mean arterial BP (MABP) along with 1.83 % (95 % CI: 0.59-3.08 %), 5.93 % (95 % CI: 0.70-11.16 %) increases in 8-OHdG and hs-CRP, respectively. Ni content was positively associated with the 8-OHdG levels whereas several other metals presented negative association with 8-OHdG and HR. Intriguingly, GSTT1+/GSTTM1+ subjects showed higher susceptibility to PM_2.5-induced alterations of DBP and PMA, and GSTT1-/GSTM1+ subjects showed higher alteration on t-PA. Taken together, our findings indicated that short-term PM_2.5 exposure induced oxidative stress, systemic inflammation, autonomic alterations, and fibrinolysis in healthy young subjects. Among multiple examined metal components Ni appeared to positively associated with systematic oxidative stress. In addition, GST-sufficient subjects might be more prone to PM_2.5-induced autonomic alterations.

Analysis of the influence of glutathione S-transferase (GSTM1 and GSTT1) genes on the risk of essential hypertension

BACKGROUND

Essential hypertension (EH) results from a complex interaction between environmental factors and an individual's genetic background.

AIM

To assess the relationship between polymorphisms in GSTM1 and GSTT1 and the risk of EH.

SUBJECTS AND METHODS

A multiplex-PCR was used to identify the genotypic profiles of GSTM1 and GSTT1 in 160 patients and 210 controls.

RESULTS

The frequency of GSTM1-null genotype was higher in patients younger than 61 years when compared to those over 61 years. Interestingly, GSTT1-null was significantly associated with the risk of EH (OR 4; 95% CI 2.6-6.3; p < 0.0001). While GSTM1-null showed no trend (OR 0.7; 95% CI 0.5-1.1, p = 0.12). Individuals carrying the combined GSTT1-null/GSTM1-null were 2.4 times more at risk for hypertension compared to those harbouring the combined GSTT1-present/GSTM1-present genotype (OR 2.4; 95% CI 1.3-4.4; p = 0.005). Additionally, the presence of the combined GSTT1-null/GSTM1-present was associated with an increased risk of EH compared to GSTT1-present/GSTM1-present carriers (OR 6.75; 95% CI 3.4-13.2; p < 0.0001).

CONCLUSION

This study showed that the GSTT1-null alone or in interaction with GSTM1-present or GSTM1-null was associated with higher risk of hypertension. Moreover, the GSTM1-null seems to be associated with the age of onset of hypertension.

Genome-Wide DNA Methylation in Policemen Working in Cities Differing by Major Sources of Air Pollution

DNA methylation is the most studied epigenetic mechanism that regulates gene expression, and it can serve as a useful biomarker of prior environmental exposure and future health outcomes. This study focused on DNA methylation profiles in a human cohort, comprising 125 nonsmoking city policemen (sampled twice), living and working in three localities (Prague, Ostrava and Ceske Budejovice) of the Czech Republic, who spent the majority of their working time outdoors. The main characterization of the localities, differing by major sources of air pollution, was defined by the stationary air pollution monitoring of PM2.5, B[a]P and NO₂. DNA methylation was analyzed by a genome-wide microarray method. No season-specific DNA methylation pattern was discovered; however, we identified 13,643 differentially methylated CpG loci (DML) for a comparison between the Prague and Ostrava groups. The most significant DML was cg10123377 (log₂FC = −1.92, p = 8.30 × 10⁻⁴) and loci annotated to RPTOR (total 20 CpG loci). We also found two hypomethylated loci annotated to the DNA repair gene XRCC5. Groups of DML annotated to the same gene were linked to diabetes mellitus (KCNQ1), respiratory diseases (PTPRN2), the dopaminergic system of the brain and neurodegenerative diseases (NR4A2). The most significant possibly affected pathway was Axon guidance, with 86 potentially deregulated genes near DML. The cluster of gene sets that could be affected by DNA methylation in the Ostrava groups mainly includes the neuronal functions and biological processes of cell junctions and adhesion assembly. The study demonstrates that the differences in the type of air pollution between localities can affect a unique change in DNA methylation profiles across the human genome.

Long-term association of ambient air pollution and hypertension in adults and in children: A systematic review and meta-analysis

AIMS

The association of long-term ambient air pollution and hypertension has been inconsistently reported. We performed an updated systematic review and meta-analysis to assess the association between long-term exposure to ambient air pollution and risk of hypertension in adults and in children.

METHODS

PubMed, EMBASE, and Web of Science were searched up to August 7, 2020 for published articles examining the association of long-term exposure to ambient air pollution, including particulate matter (PM; ultrafine particles, PM₁, PM_1-2.5, PM_2.5, PM_2.5-10 and PM₁₀), nitrogen dioxide (NO₂), nitrogen oxides (NO_x), sulfur dioxide (SO₂), ozone (O₃), carbon monoxide (CO) and hypertension. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for hypertension with each 10-μg/m³ increase in air pollutants were calculated by random-effects models.

RESULTS

We included 57 studies (53 of adults and 4 of children) in the meta-analysis. Risk of hypertension was significantly increased in adults with each 10-μg/m³ increase in exposure to PM_2.5 (OR 1.10, 95% CI 1.07-1.14; I² = 93.1%; n = 37), PM₁₀ (1.04, 1.02-1.07; I² = 44.8%; n = 22), and SO₂ (1.21, 1.08-1.36; I² = 96.6%; n = 3). Hypertension was not significantly associated with PM₁ (n = 2), PM_2.5-10 (n = 16), NO₂ (n = 27), or NO_x (n = 17). In children, the summary ORs (95% CIs) for each 10-μg/m³ increase in PM_2.5, PM₁₀, SO₂ and O₃ were 2.82 (0.51-15.68; I² = 83.8%; n = 2), 1.15 (1.01-1.32; I² = 0; n = 2), 8.57 (0.13-575.58; I² = 94.2%; n = 2), and 1.26 (0.81-1.09, I² = 91.6%; n = 2), respectively.

CONCLUSIONS

Long-term ambient air pollution is a potential risk factor for hypertension in adults. More studies are needed to explore the effects of long-term air pollution on hypertension in children.

Glutathione S-transferase, catalase, and mitochondrial superoxide dismutase gene polymorphisms modulate redox potential in systemic lupus erythematosus patients from Manaus, Amazonas, Brazil

OBJECTIVE

To investigate the frequency of glutathione S-transferase (GST), catalase, and SOD2 genetic polymorphisms and their correlation with SLE.

METHODS

A total of 290 females (patients = 151; controls= 139) were recruited. Multiplex PCR was performed for genotyping GSTM1 and GSTT1 genes, whereas real-time qPCR was used for determination of SNPs: CAT C262T, SOD2 C47T, GSTP1 A313G and GSTP1 IVS6 -C16T.

RESULTS

Thiol levels are decreased in SLE patients (p<0.001), while MDA levels were significantly higher (p<0.001) and those carrying the polymorphisms had higher rates of oxidative stress. Patients with double null deletion GSTT1^null/GSTM1^null had a frequency almost five times higher than the controls (p<0.001, OR 4.81, CI 1.98-12.11). SLE patients had a lower wild-type frequency of SOD2^CC allele compared to controls (12.4% vs 27.3%). Statistical significances were observed on the association between the GSTT1^null and GSTM1^null with SOD2^mut (p<0.001, OR 0.15, CI 0.05-0.47), with GSTP1 A303G (p=0.012, OR 0.19, CI 0.05-0.69), and with GSTP1 IVS6 (p=0.008, OR 0.14, CI 0.03-0.63). The same was observed between SOD2 C47T with GSTP1 A303G (p=0.09, OR 0.27, CI 0.09-0.74) and GSTP1 IVS6 (p=0.036, OR 0.41, CI 0.18-0.92).

CONCLUSIONS

The deletion GSTT1^null/GSTM1^null may contribute to the increased of the oxidative stress in SLE patients. Isolated GSTP1 and CAT polymorphisms do not seem to influence the increased oxidative stress, neither SLE clinical manifestations. SOD2 47^CT/TT allele may have greater oxidative stress due to structural change in the protein and decreased H₂O₂ production. The combination of polymorphic genes may be involved in the pathogenesis of the disease. Key points • Major question of our paper: Many studies have shown that the antioxidant status levels are decreased in patients with SLE, especially in severe stages of disease. We believe that this paper will be of interest to the readership of your journal had the involvement of polymorphisms and mutations in several genes that contribute to the genetic etiology of SLE, suggesting that these may influence the mechanisms of disease. • Our results. Thiol level was significantly (p<.001) lower and MDA level significantly increased (p<.001) among SLE patients. Those carrying the polymorphisms had higher rates of oxidative stress. SLE Patients had a frequency almost five times higher of double null deletion GSTT1null/GSTM1null than the controls. SLE Patients had a lower wild type frequency of SOD2CC allele compared to controls (12.4% vs 27.3%). We believed the deletion GSTT1null/GSTM1null may contribute to the increased of the oxidative stress in SLE patients while carriers of the mutant SOD2 47CT/TT allele may have greater oxidative stress due to structural change in the protein and decreased H2O2 production. The combination of polymorphic genes may be involved in the pathogenesis of the disease. • Implications of our results: Evidence for the involvement of genetic factors in severe clinical to lupus is compelling. This manuscript shows genetic insights in pathogenic pathways that may lead to severe clinical implications to LES. Therefore, it is necessary to understand their impact on overall disease pathogenesis and prognosis in these patients. We understand from general consensus about environmental factors can modify disease, however, maybe just in individuals who have a permissive genetic background. Even that no single gene predisposes some individuals to LES, we believe the genetic factors described in this manuscript are important elements in susceptibility to severe clinical to LES.

Cluster of climatic and pollutant characteristics increases admissions for acute myocardial infarction: Analysis of 30,423 patients in the metropolitan area of Sao Paulo

BACKGROUND

The impact of simultaneous adverse climate conditions in the risk of myocardial infarction (MI) was not tested before. The aim of the present study was to investigate the impact of the combination of climate and air pollution features in the number of admissions and mortality due to acute myocardial infarction in 39 municipalities of São Paulo from 2012 to 2015.

METHODS

Data about MI admissions were obtained from the Brazilian public health system (DataSUS). Daily information on weather were accessed from the Meteorological Database for Teaching and Research. Additionally, daily information on air pollution were obtained from the Environmental Company of the State of São Paulo. A hierarchical cluster analysis was applied for temperature, rainfall patterns, relative air humidity, nitrogen dioxide, particulate matter 2.5 and particulate matter 10. MI admissions and in-hospital mortality were compared among the clusters.

RESULTS

Data analysis produced 3 clusters: High temperature variation-Low humidity-high pollution (n=218 days); Intermediate temperature variation/high humidity/intermediate pollution (n=751 days) and low temperature variation/intermediate humidity-low pollution (n=123 days). All environmental variables were significantly different among clusters. The combination of high temperature variation, dry weather and high pollution resulted in a significant 9% increase in hospital admissions for MI [30.5 (IQR 25.0-36.0)]; patients/day; P<0.01). The differences in weather and pollution did not have impact on in-hospital mortality (P=0.88).

CONCLUSION

The combination of atmospheric conditions with high temperature variation, lower temperature, dryer weather and increased inhalable particles was associated with a marked increase of hospital admissions due to MI.

Exposure to traffic-related particle matter and effects on lung function and potential interactions in a cross-sectional analysis of a cohort study in west Sweden

OBJECTIVES

To investigate the long-term effects of source-specific particle matter (PM) on lung function, effects of Surfactant Protein A (SP-A) and glutathione S-transferase (GST) genes GSTP1 and GSTT1 gene variants and effect modification by single-nucleotide polymorphism (SNP) genotype.

DESIGN

Cohort study with address-based annual PM exposure assigned from annual estimates of size (PM₁₀, PM_2.5 and PM_BC) and source-specific (traffic, industry, marine traffic and wood burning) dispersion modelling.

SETTING

Gothenburg, Sweden.

PARTICIPANTS

The ADult-Onset asthma and NItric oXide Study had 6685 participants recruited from the general population, of which 5216 (78%) were included in the current study with information on all variables of interest. Mean age at the time of enrolment was 51.4 years (range 24-76) and 2427 (46.5%) were men.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁). Secondary outcome measures were effects and gene-environment interactions of SP-A and GSTT1 and GSTP1 genotypes.

RESULTS

Exposure to traffic-related PM₁₀ and PM_2.5 was associated with decreases in percent-predicted (% predicted) FEV₁ by -0.48% (95% CI -0.89% to -0.07%) and -0.47% (95% CI -0.88% to -0.07%) per IQR 3.05 and 2.47 µg/m³, respectively, and with decreases in % predicted FVC by -0.46% (95% CI -0.83% to -0.08%) and -0.47% (95% CI -0.83% to -0.10%). Total and traffic-related PM_BC was strongly associated with both FEV₁ and FVC by -0.53 (95% CI -0.94 to -0.13%) and -0.43% (95% CI -0.77 to -0.09%) per IQR, respectively, for FVC, and similarly for FEV₁. Minor allele carrier status for two GSTP1 SNPs and the GSTT1 null genotype were associated with decreases in % predicted lung function. Three SP-A SNPs showed effect modification with exposure to PM_2.5 from industry and marine traffic.

CONCLUSIONS

PM exposure, specifically traffic related, was associated with FVC and FEV₁ reductions and not modified by genotype. Genetic effect modification was suggested for industry and marine traffic PM_2.5.

Oxidative stress pathways of air pollution mediated toxicity: Recent insights

Ambient air pollution is a leading environmental cause of morbidity and mortality globally with most of the outcomes of cardiovascular origin. While numerous mechanisms are proposed to explain the link between air pollutants and cardiovascular events, the evidence supports a role for oxidative stress as a critical intermediary pathway in the transduction of systemic responses in the cardiovascular system. Indeed, alterations in vascular function are a critical step in the development of cardiometabolic disorders such as hypertension, diabetes, and atherosclerosis. This review will provide an overview of the impact of particulate and gaseous pollutants on oxidative stress from human and animal studies published in the last five years. We discuss current gaps in knowledge and evidence to date implicating the role of oxidative stress with an emphasis on inhalational exposures. We conclude with the identification of gaps, and an exhortation for further studies to elucidate the impact of oxidative stress in air pollution mediated effects.

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Particulate matter air pollution is the leading risk factor for cardiovascular morbidity and mortality globally.

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Mechanisms of oxidative stress mediated pathways.

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How does lung inflammation crucial to inhalational exposure mediate systemic toxicity?

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Review of recent animal and human exposure studies providing insights into oxidative stress pathways.

Oxidative stress and the cardiovascular effects of air pollution

Cardiovascular causes have been estimated to be responsible for more than two thirds of the considerable mortality attributed to air pollution. There is now a substantial body of research demonstrating that exposure to air pollution has many detrimental effects throughout the cardiovascular system. Multiple biological mechanisms are responsible, however, oxidative stress is a prominent observation at many levels of the cardiovascular impairment induced by pollutant exposure. This review provides an overview of the evidence that oxidative stress is a key pathway for the different cardiovascular actions of air pollution.

Antioxidant genes and susceptibility to air pollution for respiratory and cardiovascular health

Oxidative stress occurs when antioxidant defences, which are regulated by a complex network of genes, are insufficient to maintain the level of reactive oxygen species below a toxic threshold. Outdoor air pollution has long been known to adversely affect health and one prominent mechanism of action common to all pollutants is the induction of oxidative stress. An individual's susceptibility to the effects of air pollution partly depends on variation in their antioxidant genes. Thus, understanding antioxidant gene-pollution interactions has significant potential clinical and public health impacts, including the development of targeted and cost-effective preventive measures, such as setting appropriate standards which protect all members of the population. In this review, we aimed to summarize the latest epidemiological evidence on interactions between antioxidant genes and outdoor air pollution, in the context of respiratory and cardiovascular health. The evidence supporting the existence of interactions between antioxidant genes and outdoor air pollution is strongest for childhood asthma and wheeze, especially for interactions with GSTT1, GSTM1 and GSTP1, for lung function in both children and adults for several antioxidant genes (GSTT1, GSTM1, GSTP1, HMOX1, NQO1, and SOD2) and, to a more limited extent, for heart rate variability in adults for GSTM1 and HMOX1. Methodological challenges hampering a clear interpretation of these findings and understanding of true potential heterogeneity are discussed.

Biomarkers of exposure, effect, and susceptibility in occupational exposure to traffic-related air pollution: A review

There is a well-recognized association between environmental air pollution exposure and several human diseases. However, the relationship between diseases related to occupational air pollution exposure on roads and high levels of traffic-related air pollutants (TRAPs) is less substantiated. Biomarkers are essential tools in environmental and occupational toxicology, and studies on new biomarkers are increasingly relevant due to the need to determine early biomarkers to be assessed in exposure conditions. This review aimed to investigate the main advances in the biomonitoring of subjects occupationally exposed to air pollution, as well as to summarize the biomarkers of exposure, effect, and susceptibility. Furthermore, we discuss how biomarkers could be used to complement the current application of methods used to assess occupational exposures to xenobiotics present in air pollution. The databases used in the preparation of this review were PubMed, Scopus, and Science Direct. Considering the significant deleterious effects on health associated with chronic occupational exposure to xenobiotics, this topic deserves attention. As it is difficult to avoid occupational exposure to TRAPs, biomonitoring should be applied as a strategy to reduce the toxic effects of workplace exposure.

Exposure to ambient air pollution and the incidence of congestive heart failure and acute myocardial infarction: A population-based study of 5.1 million Canadian adults living in Ontario

Long-term exposure to ambient air pollution has been linked to cardiovascular mortality, but the associations with incidence of major cardiovascular diseases are not fully understood, especially at low concentrations. We aimed to investigate the associations between exposure to fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), ozone (O₃), redox-weighted average of NO₂ and O₃ (O_x) and incidence of congestive heart failure (CHF) and acute myocardial infarction (AMI). Our study population included all long-term residents aged 35-85 years who lived in Ontario, Canada, from 2001 to 2015 (~5.1 million). Incidence of CHF and AMI were ascertained from validated registries. We assigned estimates of annual concentrations of pollutants to the residential postal codes of subjects for each year during follow-up. We estimated hazard ratios (HRs) and 95% CIs for each pollutant separately using Cox proportional hazards models. We examined the shape of concentration-response associations using shape-constrained health impact functions. From 2001 to 2015, there were 422,625 and 197,628 incident cases of CHF and AMI, respectively. In the fully adjusted analyses, the HRs of CHF corresponding to each interquartile range increase in exposure were 1.05 (95% CI: 1.04-1.05) for PM_2.5, 1.02 (95% CI: 1.01-1.04) for NO₂, 1.03 (95% CI: 1.02-1.03) for O₃, and 1.02 (95% CI: 1.02-1.03) for O_x, respectively. Similarly, exposure to PM_2.5, O₃, and O_x were positively associated with AMI. The concentration-response relationships were different for individual pollutant and outcome combinations (e.g., for PM_2.5 the relationship was supralinear with CHF, and linear with AMI).

Fine particle environmental pollution and cardiovascular diseases

Air pollution affects 90% of the world's population and has caused 9 million deaths in 2015, becoming the most important cause of premature deaths in the world. Exposure to fine particulate matter, a major component of urban air pollution, has been associated with an increase in cardiovascular risk and associated mortality. Impact of fine particles on the cardiovascular system includes inflammation, activation of prothrombotic pathways, oxidative stress, vascular dysfunction and remodeling, and neurological dysfunction. Genetic and epigenetic factors might also increase the susceptibility to air pollution. Consequently, epidemiologic studies have identified correlations between air particulate matter concentrations and acute coronary events, ischemic cardiomyopathy, acute heart failure, and stroke. Interestingly, these effects are present even for fine particulate matter concentrations below current US and EU regulatory standards, and seems to be more harmful in the most fragile population such as low-income or elderly subjects, or patients with previous cardiovascular disease. This review aims to summarize recent data on the pathophysiology and epidemiology of cardiovascular disease after particulate matter exposure. It will also discuss potential strategies to reduce the impact of air pollution on current and future populations' health.

Exposure to lipopolysaccharide (LPS) reduces contractile response of small airways from GSTCD-/- mice

Introduction

Genome-Wide Association Studies suggest glutathione S transferase C terminal domain (GSTCD) may play a role in development of Chronic Obstructive Pulmonary Disease. We aimed to define the potential role of GSTCD in airway inflammation and contraction using precision cut lung slice (PCLS) from wild-type (GSTCD^+/+) and GSTCD knockout mice (GSTCD^-/-).

Methods

PCLS from age and gender matched GSTCD^+/+ and GSTCD^-/- mice were prepared using a microtome. Contraction was studied after applying either a single dose of Methacholine (Mch) (1 μM) or different doses of Mch (0.001 to 100 μM). Each slice was then treated with lipopolysaccharide (LPS) or vehicle (PBS) for 24 hours. PCLS contraction in the same airway was repeated before and after stimulation. Levels of TNFα production was also measured.

Results

There were no differences in contraction of PCLS from GSTCD^+/+ and GSTCD^-/- mice in response to Mch (EC₅₀ of GSTCD^+/+ vs GSTCD^-/- animals: 100.0±20.7 vs 107.7±24.5 nM, p = 0.855, n = 6 animals/group). However, after LPS treatment, there was a 31.6% reduction in contraction in the GSTCD^-/- group (p = 0.023, n = 6 animals). There was no significant difference between PBS and LPS treatment groups in GSTCD^+/+ animals. We observed a significant increase in TNFα production induced by LPS in GSTCD^-/- lung slices compared to the GSTCD^+/+ LPS treated slices.

Conclusion

GSTCD knockout mice showed an increased responsiveness to LPS (as determined by TNFα production) that was accompanied by a reduced contraction of small airways in PCLS. These data highlight an unrecognised potential function of GSTCD in mediating inflammatory signals that affect airway responses.

Interactions of CDH13 gene polymorphisms and ambient PM10 air pollution exposure with blood pressure and hypertension in Korean men

Associations between air pollution and blood pressure (BP) traits can be modified by several candidate genes, which might explain differences in individual genetic susceptibility. Based on recent evidence hypothesized to link air pollution and BP traits, we examined whether the polymorphisms of CDH13-a candidate gene-would modify the relationship between them in adult Korean men. A total of 1816 subjects were included. We divided them into two groups of high or low to moderate exposure using the annual average concentration of particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀). We conducted an interaction analysis of PM₁₀ exposure using 200 single-nucleotide polymorphisms (SNPs), located within CDH13, in subjects with regard to BP traits and hypertension. The rs7500599 intronic SNP of CDH13 had the strongest signals for all BP traits including systolic blood pressure (SBP), diastolic blood pressure, and hypertension, by interacting with PM₁₀ exposure. An additional stratified analysis showed that the effects of PM₁₀ exposure on elevated BP and hypertension increased gradually in proportion to the number of minor alleles in this SNP. In addition, PM₁₀ exposure in the TT or GT genotype groups did not show significant associations with BP traits, whereas in a homozygous risk allele (GG) group, PM₁₀ exposure was significantly associated with BP traits and hypertension. For SBP, these patterns were reproducible at two independent sampling sites. This CDH13 polymorphism amplifies the negative associations of PM₁₀ exposure and elevated BP or hypertension in Korean men.

Glutathione S-Transferase M1 and T1 polymorphisms and hypertension risk: an updated meta-analysis

Recently, Glutathione S-transferase M1 (GSTM1), glutathione S-transferase T1 (GSTT1), and their interaction with hypertension risk have been focused on. However, the results of previous studies have been inconsistent. Hence, the present meta-analysis was performed to explore the association. Twenty-two case-control studies met the inclusion criteria for GSTM1 (including 3577 hypertension cases and 3784 controls), twenty-two for GSTT1 (including 3741 cases and 4444 controls), and nine for their combined effects (including 1073 cases and 781 controls). Pooled analyses on the association between GSTM1 present/null polymorphism and hypertension risk were observed to be insignificant in overall and subgroup analyses. The individual who carries the GSTT1 null-genotype had a statistically significant overall population (OR = 1.28, 95% CI: 1.03, 1.60), Indians (OR = 2.45, 95% CI: 1.08, 5.59), and hospital-based controls (OR = 1.53, 95% CI: 1.21, 1.94). For the GSTM1-GSTT1 interaction, we found that the GSTM1/GSTT1 double-null-genotype was significantly associated with hypertension risks (double-null vs. double-present: OR = 2.68, 95% CI: 1.06, 6.81). To summarize, this meta-analysis indicates that Indians with the GSTT1 null-genotype has a raised hypertension risks; the GSTM1 null/GSTT1 null-genotype is association with raised hypertension risks, while the GSTM1 null-genotype is not associated with hypertension risks. In addition, I² > 75% cannot be eliminated for GSTM1 in Indians or Asians, hence, it will be very important to explore the GSTM1 null-genotype and hypertension susceptibility in Indians and Asians for a large new sample, on population-based control study.

Longitudinal Analysis of Long-Term Air Pollution Levels and Blood Pressure: A Cautionary Tale from the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Air pollution exposures are hypothesized to impact blood pressure, yet few longitudinal studies exist, their findings are inconsistent, and different adjustments have been made for potentially distinct confounding by calendar time and age.

OBJECTIVE

We aimed to investigate the associations of long- and short-term [Formula: see text] and [Formula: see text] concentrations with systolic and diastolic blood pressures and incident hypertension while also accounting for potential confounding by age and time.

METHODS

Between 2000 and 2012, Multi-Ethnic Study of Atherosclerosis participants were measured for systolic and diastolic blood pressure at five exams. We estimated annual average and daily [Formula: see text] and [Formula: see text] concentrations for 6,569 participants using spatiotemporal models and measurements, respectively. Associations of exposures with blood pressure corrected for medication were studied using mixed-effects models. Incident hypertension was examined with Cox regression. We adjusted all models for sex, race/ethnicity, socioeconomic status, smoking, physical activity, diet, season, and site. We compared associations from models adjusting for time-varying age with those that adjusted for both time-varying age and calendar time.

RESULTS

We observed decreases in pollution and blood pressures (adjusted for age and medication) over time. Strong, positive associations of long- and short-term exposures with blood pressure were found only in models with adjustment for time-varying age but not adjustment for both time-varying age and calendar time. For example, [Formula: see text] higher annual average [Formula: see text] concentrations were associated with 2.7 (95% CI: 1.5, 4.0) and [Formula: see text] (95% CI: [Formula: see text] 1.0) mmHg in systolic blood pressure with and without additional adjustment for time, respectively. Associations with incident hypertension were similarly weakened by additional adjustment for time. Sensitivity analyses indicated that air pollution did not likely cause the temporal trends in blood pressure.

CONCLUSIONS

In contrast to experimental evidence, we found no associations between long- or short-term exposures to air pollution and blood pressure after accounting for both time-varying age and calendar time. This research suggests that careful consideration of both age and time is needed in longitudinal studies with trending exposures. https://doi.org/10.1289/EHP2966.

Atopic dermatitis: Interaction between genetic variants of GSTP1, TNF, TLR2, and TLR4 and air pollution in early life

BACKGROUND

Associations between traffic-related air pollution (TRAP) and childhood atopic dermatitis (AD) remain inconsistent, possibly due to unexplored gene-environment interactions. The aim of this study was to examine whether a potential effect of TRAP on AD prevalence in children is modified by selected single nucleotide polymorphisms (SNPs) related to oxidative stress and inflammation.

METHODS

Doctor-diagnosed AD up to age 2 years and at 7-8 years, as well as AD symptoms up to age 2 years, was assessed using parental-reported questionnaires in six birth cohorts (N = 5685). Associations of nitrogen dioxide (NO₂ ) estimated at the home address of each child at birth and nine SNPs within the GSTP1, TNF, TLR2, or TLR4 genes with AD were examined. Weighted genetic risk scores (GRS) were calculated from the above SNPs and used to estimate combined marginal genetic effects of oxidative stress and inflammation on AD and its interaction with TRAP.

RESULTS

GRS was associated with childhood AD and modified the association between NO₂ and doctor-diagnosed AD up to the age of 2 years (P(interaction) = .029). This interaction was mainly driven by a higher susceptibility to air pollution in TNF rs1800629 minor allele (A) carriers. TRAP was not associated with the prevalence of AD in the general population.

CONCLUSIONS

The marginal genetic association of a weighted GRS from GSTP1, TNF, TLR2, and TLR4SNPs and its interaction with air pollution supports the role of oxidative stress and inflammation in AD.

Global association between ambient air pollution and blood pressure: A systematic review and meta-analysis

Although numerous studies have investigated the association of ambient air pollution with hypertension and blood pressure (BP), the results were inconsistent. We performed a comprehensive systematic review and meta-analysis of these studies. Seven international and Chinese databases were searched for studies examining the associations of particulate (diameter<2.5 μm (PM_2.5), 2.5-10 μm (PM_2.5-10) or >10 μm (PM₁₀)) and gaseous (sulfur dioxide (SO₂), nitrogen dioxide (NO₂), nitrogen oxides (NO_x), ozone (O₃), carbon monoxide (CO)) air pollutants with hypertension or BP. Odds ratios (OR), regression coefficients (β) and their 95% confidence intervals were calculated to evaluate the strength of the associations. Subgroup analysis, sensitivity analysis, and meta-regression analysis were also conducted. The overall meta-analysis showed significant associations of long-term exposures to PM_2.5 with hypertension (OR = 1.05), and of PM₁₀, PM_2.5, and NO₂ with DBP (β values: 0.47-0.86 mmHg). In addition, short-term exposures to four (PM₁₀, PM_2.5, SO₂, NO₂), two (PM_2.5 and SO₂), and four air pollutants (PM₁₀, PM_2.5, SO₂, and NO₂), were significantly associated with hypertension (ORs: 1.05-1.10), SBP (β values: 0.53-0.75 mmHg) and DBP (β values: 0.15-0.64 mmHg), respectively. Stratified analyses showed a generally stronger relationship among studies of men, Asians, North Americans, and areas with higher air pollutant levels. In conclusion, our study indicates a positive association between ambient air pollution and increased BP and hypertension. Geographical and socio-demographic factors may modify the pro-hypertensive effects of air pollutants.

Effect of Particulate Matter Air Pollution on Cardiovascular Oxidative Stress Pathways

SIGNIFICANCE

Particulate matter (PM) air pollution is a leading cause of global cardiovascular morbidity and mortality. Understanding the biological action of PM is of particular importance in improvement of public health. Recent Advances: Both fine (PM <2.5 μM) and ultrafine particles (<0.1 μM) are widely believed to mediate their effects through redox regulated pathways. A rather simplistic graded ramp model of redox stress has been replaced by a more sophisticated understanding of the role of oxidative stress in signaling, and the realization that many of the observed effects may involve disruption and/or enhancement of normal endogenous redox signaling and induction of a potent immune-mediated response, through entrainment of multiple reactive oxygen species (ROS).

CRITICAL ISSUES

The molecular events by which pulmonary oxidative stress in response to inhalational exposure to air pollution triggers inflammation, major ROS (e.g., superoxide, hydroxyl radical, nitric oxide, and peroxynitrite) generated in air pollution exposure, types of oxidative tissue damage in target organs, contributions of nonimmune and immune cells in inflammation, and the role of protective proteins (e.g., surfactant, proteins, and antioxidants) are highly complex and may differ depending on models and concomitant disease states.

FUTURE DIRECTIONS

While the role of oxidative stress in the lung has been well demonstrated, the role of oxidative stress in mediating systemic effects especially in inflammation and injury processes needs further work. The role of antioxidant defenses with chronic exposure will also need further exploration. Antioxid. Redox Signal. 28, 797-818.

Role of oxidative stress in cardiovascular disease outcomes following exposure to ambient air pollution

Exposure to ambient air pollution is associated with adverse cardiovascular outcomes. These are manifested through several, likely overlapping, pathways including at the functional level, endothelial dysfunction, atherosclerosis, pro-coagulation and alterations in autonomic nervous system balance and blood pressure. At numerous points within each of these pathways, there is potential for cellular oxidative imbalances to occur. The current review examines epidemiological, occupational and controlled exposure studies and research employing healthy and diseased animal models, isolated organs and cell cultures in assessing the importance of the pro-oxidant potential of air pollution in the development of cardiovascular disease outcomes. The collective body of data provides evidence that oxidative stress (OS) is not only central to eliciting specific cardiac endpoints, but is also implicated in modulating the risk of succumbing to cardiovascular disease, sensitivity to ischemia/reperfusion injury and the onset and progression of metabolic disease following ambient pollution exposure. To add to this large research effort conducted to date, further work is required to provide greater insight into areas such as (a) whether an oxidative imbalance triggers and/or worsens the effect and/or is representative of the consequence of disease progression, (b) OS pathways and cardiac outcomes caused by individual pollutants within air pollution mixtures, or as a consequence of inter-pollutant interactions and (c) potential protection provided by nutritional supplements and/or pharmacological agents with antioxidant properties, in susceptible populations residing in polluted urban cities.

A combined linkage and association strategy identifies a variant near the GSTP1 gene associated with BMI in the Mexican population

Obesity is a major public health concern in Mexico and worldwide. Although the estimated heritability is high, common variants identified by genome-wide association studies explain only a small proportion of this heritability. A combination of linkage and association strategies could be a more robust and powerful approach to identify other obesity-susceptibility variants. We thus sought to identify novel genetic variants associated with obesity-related traits in the Mexican population by combining these methods. We performed a genome-wide linkage scan for body mass index (BMI) and other obesity-related phenotypes in 16 Mexican families using the Sequential Oligogenic Linkage Analysis Routines Program. Associated single-nucleotide polymorphisms (SNPs) were tested for associations in an independent cohort. Two suggestive BMI-linkage peaks (logarithm of odds ⩾1.5) were observed at chromosomal regions 11q13 and 13q22. Only rs614080 in the 11q13 region was significantly associated with BMI and related traits in these families. This association was also significant in an independent cohort of Mexican adults. Moreover, this variant was significantly associated with GSTP1 gene expression levels in adipose tissue. In conclusion, the rs614080 SNP near the GSTP1 gene was significantly associated with BMI and GSTP1 expression levels in the Mexican population.

Glutathione S-Transferase T1 (GSTT1) Null Polymorphism, Smoking, and Their Interaction in Coronary Heart Disease: A Comprehensive Meta-Analysis

BACKGROUND

The association between glutathione S-transferase T1 (GSTT1) null polymorphism and coronary heart disease (CHD) is inconsistent among studies, and data on the GSTT1 null genotype-smoking interplay in CHD is lacking. We conducted this meta-analysis to investigate the relationship between GSTT1 null polymorphism and CHD and to assess the potential interaction between GSTT1 null genotype and smoking.

METHODS

PubMed and EMBASE databases were searched up to 27 January 2016 using the appropriate terms. Odds ratios were pooled using either fixed-effects or random-effects models.

RESULTS

Twenty-nine articles including 31 studies with 15,004 cases and 35,597 controls were eligible. The random-effects model showed that the GSTT1 null genotype was associated with increased CHD risk (OR=1.213, 95%CI: 1.004-1.467; I²=90.4%). After excluding 10 studies detected by Galbraith plot, the fixed effects summary estimate also showed an increased risk of CHD (OR=1.14, 95% CI: 1.06-1.22; I²=27.7%). A case-only analysis including eight studies showed a statistically significant positive interaction between GSTT1 null polymorphism and smoking status on CHD (OR=1.34, 95% CI: 1.09-1.64; I²=0%). Sensitivity analyses further supported the associations. No publication bias was observed.

CONCLUSIONS

This meta-analysis suggests that GSTT1 null polymorphism is associated with the risk of CHD. To our knowledge, this is the first meta-analysis to prove a positive effect of the interaction between GSTT1 null genotype and smoking status on the risk of CHD. Future studies with detailed individual information are needed to confirm our findings.

Associations of Short-Term and Long-Term Exposure to Ambient Air Pollutants With Hypertension

Hypertension is a major disease of burden worldwide. Previous studies have indicated that air pollution might be a risk factor for hypertension, but the results were controversial. To fill this gap, we performed a meta-analysis of epidemiological studies to investigate the associations of short-term and long-term exposure to ambient air pollutants with hypertension. We searched all of the studies published before September 1, 2015, on the associations of ozone (O 3 ), carbon monoxide (CO), nitrogen oxide (NO 2 and NO X ), sulfur dioxide (SO 2 ), and particulate matter (PM 10 and PM 2.5 ) with hypertension in the English electronic databases. A pooled odds ratio (OR) for hypertension in association with each 10 μg/m 3 increase in air pollutant was calculated by a random-effects model (for studies with significant heterogeneity) or a fixed-effect model (for studies without significant heterogeneity). A total of 17 studies examining the effects of short-term (n=6) and long-term exposure (n=11) to air pollutants were identified. Short-term exposure to SO 2 (OR=1.046, 95% confidence interval [CI]: 1.012–1.081), PM 2.5 (OR=1.069, 95% CI: 1.003–1.141), and PM 10 (OR=1.024, 95% CI: 1.016–1.032) were significantly associated with hypertension. Long-term exposure (a 10 μg/m 3 increase) to NO 2 (OR=1.034, 95% CI: 1.005–1.063) and PM 10 (OR=1.054, 95% CI: 1.036–1.072) had significant associations with hypertension. Exposure to other ambient air pollutants (short-term exposure to NO 2 , O 3 , and CO and long-term exposure to NO x , PM 2.5 , and SO 2 ) also had positive relationships with hypertension, but lacked statistical significance. Our results suggest that short-term or long-term exposure to some air pollutants may increase the risk of hypertension.

The Association between Gene-Environment Interactions and Diseases Involving the Human GST Superfamily with SNP Variants

Exposure to environmental hazards has been associated with diseases in humans. The identification of single nucleotide polymorphisms (SNPs) in human populations exposed to different environmental hazards, is vital for detecting the genetic risks of some important human diseases. Several studies in this field have been conducted on glutathione S-transferases (GSTs), a phase II detoxification superfamily, to investigate its role in the occurrence of diseases. Human GSTs consist of cytosolic and microsomal superfamilies that are further divided into subfamilies. Based on scientific search engines and a review of the literature, we have found a large amount of published articles on human GST super- and subfamilies that have greatly assisted in our efforts to examine their role in health and disease. Because of its polymorphic variations in relation to environmental hazards such as air pollutants, cigarette smoke, pesticides, heavy metals, carcinogens, pharmaceutical drugs, and xenobiotics, GST is considered as a significant biomarker. This review examines the studies on gene-environment interactions related to various diseases with respect to single nucleotide polymorphisms (SNPs) found in the GST superfamily. Overall, it can be concluded that interactions between GST genes and environmental factors play an important role in human diseases.

Associations of air pollution exposure with blood pressure and heart rate variability are modified by oxidative stress genes: A repeated-measures panel among elderly urban residents

BACKGROUND

Oxidative stress has been suggested as a major cause of elevated blood pressure (BP) and reduced heart rate variability (HRV) due to air pollution. We hypothesized that the associations of air pollution exposure with BP and HRV are modified by oxidative stress gene polymorphisms.

METHODS

Between 2008 and 2010, we conducted up to 5 surveys of 547 elderly participants, measured their BP and HRV, and genotyped 47 single nucleotide polymorphisms (SNPs) in 18 oxidative stress genes. Linear mixed models were constructed to evaluate the associations of particulate matter ≤10 μm, nitrogen dioxide, and sulfur dioxide with BP and HRV, as well as the modifications of these associations by the genotyped SNPs.

RESULTS

Single-SNP analyses revealed interactions between air pollution and 15 SNPs (for BP) and 33 SNPs (for HRV) (all, P for interaction < 0.05). When we generated genetic risk scores for BP and HRV, using the SNPs with interactions in the single-SNP models, we found that associations of air pollution exposure with BP and HRV were modified by the genetic risk scores (P for interaction < 0.05).

CONCLUSIONS

These results strongly suggest that the associations of air pollution with BP and HRV are mediated by oxidative stress pathways.

Air Pollution and Acute Myocardial Infarction Hospital Admission in Alberta, Canada: A Three-Step Procedure Case-Crossover Study

Adverse associations between air pollution and myocardial infarction (MI) are widely reported in medical literature. However, inconsistency and sensitivity of the findings are still big concerns. An exploratory investigation was undertaken to examine associations between air pollutants and risk of acute MI (AMI) hospitalization in Alberta, Canada. A time stratified case-crossover design was used to assess the transient effect of five air pollutants (carbon monoxide (CO), nitrogen dioxide (NO₂), nitric oxide (NO), ozone (O₃) and particulate matter with an aerodynamic diameter ≤2.5 (PM_2.5)) on the risk of AMI hospitalization over the period 1999–2009. Subgroups were predefined to see if any susceptible group of individuals existed. A three-step procedure, including univariate analysis, multivariate analysis, and bootstrap model averaging, was used. The multivariate analysis was used in an effort to address adjustment uncertainty; whereas the bootstrap technique was used as a way to account for regression model uncertainty. There were 25,894 AMI hospital admissions during the 11-year period. Estimating health effects that are properly adjusted for all possible confounding factors and accounting for model uncertainty are important for making interpretations of air pollution–health effect associations. The most robust findings included: (1) only 1-day lag NO₂ concentrations (6-, 12- or 24-hour average), but not those of CO, NO, O₃ or PM_2.5, were associated with an elevated risk of AMI hospitalization; (2) evidence was suggested for an effect of elevated risk of hospitalization for NSTEMI (Non-ST Segment Elevation Myocardial Infarction), but not for STEMI (ST segment elevation myocardial infarction); and (3) susceptible subgroups included elders (age ≥65) and elders with hypertension. As this was only an exploratory study there is a need to replicate these findings with other methodologies and datasets.