PM2.5 concentration in the ambient air is a risk factor for the development of high-risk coronary plaques

Long-term ambient air pollution and coronary atherosclerosis: Results from the Swedish SCAPIS study

BACKGROUND AND AIMS

Despite firm evidence for an association between long-term ambient air pollution exposure and cardiovascular morbidity and mortality, results from epidemiological studies on the association between air pollution exposure and atherosclerosis have not been consistent. We investigated associations between long-term low-level air pollution exposure and coronary atherosclerosis.

METHODS

We performed a cross-sectional analysis in the large Swedish CArdioPulmonary bioImaging Study (SCAPIS, n = 30 154), a random general population sample. Concentrations of total and locally emitted particulate matter <2.5 μm (PM2.5), <10 μm (PM10), and nitrogen oxides (NOx) at the residential address were modelled using high-resolution dispersion models. We estimated associations between air pollution exposures and segment involvement score (SIS), coronary artery calcification score (CACS), number of non-calcified plaques (NCP), and number of significant stenoses, using ordinal regression models extensively adjusted for potential confounders.

RESULTS

Median 10-year average PM2.5 exposure was 6.2 μg/m3 (range 3.5-13.4 μg/m3). 51 % of participants were women and 51 % were never-smokers. None of the assessed pollutants were associated with a higher SIS or CACS. Exposure to PM2.5 was associated with NCP (adjusted OR 1.34, 95 % CI 1.13, 1.58, per 2.05 μg/m3). Associations with significant stenoses were inconsistent.

CONCLUSIONS

In this large, middle-aged general population sample with low exposure levels, air pollution was not associated with measures of total burden of coronary atherosclerosis. However, PM2.5 appeared to be associated with a higher prevalence of non-calcified plaques. The results suggest that increased risk of early-stage atherosclerosis or rupture, but not increased total atherosclerotic burden, may be a pathway for long-term air pollution effects on cardiovascular disease.

Exposome in ischaemic heart disease: beyond traditional risk factors

Ischaemic heart disease represents the leading cause of morbidity and mortality, typically induced by the detrimental effects of risk factors on the cardiovascular system. Although preventive interventions tackling conventional risk factors have helped to reduce the incidence of ischaemic heart disease, it remains a major cause of death worldwide. Thus, attention is now shifting to non-traditional risk factors in the built, natural, and social environments that collectively contribute substantially to the disease burden and perpetuate residual risk. Of importance, these complex factors interact non-linearly and in unpredictable ways to often enhance the detrimental effects attributable to a single or collection of these factors. For this reason, a new paradigm called the 'exposome' has recently been introduced by epidemiologists in order to define the totality of exposure to these new risk factors. The purpose of this review is to outline how these emerging risk factors may interact and contribute to the occurrence of ischaemic heart disease, with a particular attention on the impact of long-term exposure to different environmental pollutants, socioeconomic and psychological factors, along with infectious diseases such as influenza and COVID-19. Moreover, potential mitigation strategies for both individuals and communities will be discussed.

Particulate Matter Air Pollution is a Significant Risk Factor for Cardiovascular Disease

Air pollution is responsible worldwide for 9-12 million deaths annually. The major contributor to air pollution is particulate matter ≤2.5 µg per cubic meter of air (PM2.5) from vehicles, industrial emissions, and wildfire smoke. United States ambient air standards recommend annual average PM2.5 concentrations of ≤12 μg/m³ while European standards allow an average annual PM2.5 concentration of ≤20 μg/m3. However, significant PM2.5 cardiovascular and pulmonary health risks exist below these concentrations. Chronic PM2.5 exposure significantly increases major cardiovascular and pulmonary event risks in Americans by 8 to more than 20% for each 10-μg/m3 increase in PM2.5. PM2.5-induced increases in lipid peroxidation, induction of vascular inflammation and endothelial cell injury initiate and propagate respiratory diseases, coronary and carotid atherosclerosis. PM2.5 can cause atherosclerotic vascular plaque rupture and myocardial infarction and stroke by activating metalloproteinases. This article discusses PM2.5 effects on the cardiovascular and pulmonary systems, specific PM2.5 pathophysiologic mechanisms contributing to cardiopulmonary disease, and preventive measures to limit the cardiovascular and pulmonary effects of PM2.5.

Association between long-term exposure to ambient air pollution and lesion ischemia in patients with atherosclerosis

BACKGROUND AND AIMS

Air pollution has been associated with coronary artery disease. The underlying mechanisms were understudied, especially in relation to coronary stenosis leading to myocardial ischemia. Advances in computed tomography (CT) allow for novel quantification of lesion ischemia. We aim to investigate associations between air pollution exposures and fractional flow reserve on CT (CT-FFR), a measure of coronary artery blood flow.

METHODS

CT-FFR, which defines a ratio of maximal myocardial blood flow compared to its normal value (range: 0-100%), was characterized in 2017 patients with atherosclerosis between 2015 and 2017. Exposures to ozone (O3), nitrogen dioxide (NO2), and fine particulate matter (PM2.5) were estimated using high-resolution exposure models. Linear and logistic regression models were used to assess the association of each air pollutant with CT-FFR and with the prevalence of clinically relevant myocardial ischemia (CT-FFR <75%).

RESULTS

Participants were on average 60.1 years old. Annual mean O3, NO2, PM2.5 were 61, 47 and 60 μg/m3, respectively. Mean CT-FFR value was 76.9%. In the main analysis, a higher level of O3 was associated with a lower CT-FFR value (-1.74%, 95% CI: -2.85, -0.63 per 8 μg/m3) and a higher prevalence of myocardial ischemia (odds ratio: 1.32, 95% CI: 1.05-1.65), adjusting for potential confounders such as risk factors and plaque phenotypes, independent of the effects of exposure to NO2 and PM2.5. No associations were observed for PM2.5 or NO2 with CT-FFR.

CONCLUSIONS

Long-term exposure to O3 is associated with lower CT-FFR value in atherosclerotic patients, indicating higher risk of lesion ischemia.

Association of air pollution exposure and increased coronary artery disease risk: the modifying effect of genetic susceptibility

BACKGROUND

Both genetic factors and air pollution are risk factors for coronary artery disease (CAD), but their combined effects on CAD are uncertain. The study aimed to comprehensively investigate their separate, combined and interaction effects on the onset of CAD.

METHODS

We utilized data from the UK Biobank with a recruitment of 487,507 participants who were free of CAD at baseline from 2006 to 2010. We explored the separate, combined effect or interaction association among genetic factors, air pollution and CAD with the polygenic risk score (PRS) and Cox proportional hazard models.

RESULTS

The hazard ratios (HRs) [95% confidence interval (CI)] of CAD for 10-µg/m3 increases in PM2.5, NO2 and NOx concentrations were 1.25 (1.09, 1.44), 1.03 (1.01, 1.05) and 1.01 (1.00, 1.02), respectively. Participants with high PRS and air pollution exposure had a higher risk of CAD than those with the low genetic risk and low air pollution exposure, and the HRs (95% CI) of CAD in the PM2.5, PM10, NO2 and NOx high joint exposure groups were 1.56 (1.48, 1.64), 1.55(1.48, 1.63), 1.57 (1.49, 1.65), and 1.57 (1.49, 1.65), respectively. Air pollution and genetic factors exerted significant additive effects on the development of CAD (relative excess risk due to the interaction [RERI]: 0.12 (0.05, 0.19) for PM2.5, 0.17 (0.10, 0.24) for PM10, 0.14 (0.07, 0.21) for NO2, and 0.17 (0.10, 0.24) for NOx; attributable proportion due to the interaction [AP]: 0.09 (0.04, 0.14) for PM2.5, 0.12 (0.07, 0.18) for PM10, 0.11 (0.06, 0.16) for NO2, and 0.13 (0.08, 0.18) for NOx).

CONCLUSION

Exposure to air pollution was significantly related to an increased CAD risk, which could be further strengthened by CAD gene susceptibility. Additionally, there were positive additive interactions between genetic factors and air pollution on the onset of CAD. This can provide a more comprehensive, precise and individualized scientific basis for the risk assessment, prevention and control of CAD.

[Effects of air pollution on cardiovascular events in cardiac intensive care units]

Many environmental factors influence the occurrence of cardiovascular events. Among these, air pollution is certainly the most harmful, due to its dual composition and effects. Air pollution is both particulate and gaseous, and can vary in concentration and composition according to its source and type of emission. Moreover, clinical effects are not only observed at long-term but also at short-term, following rapid deterioration in air quality. Air pollution must therefore be seen both as a risk factor for atherosclerotic disease, and as a trigger for cardiovascular events. These acute effects are essentially mediated by an increased risk of acute coronary syndromes and heart failure. The effects of air pollution on admissions for ventricular arrhythmias and arterial hypertension are also possible. The cardiotoxicity of pollution is mainly mediated by sympatho-vagal imbalance, by the initiation and amplification of an oxidative, inflammatory and pro-aggregatory cascade, and by endothelial dysfunction and activation of metalloproteinases. Although now well established, the consequences of air pollution on acute cardiovascular events require further investigation. Environmental cardiology is an emerging discipline whose current vision still fails to integrate qualitative aspects, such as the oxidative potential of particulate matter, and the joint effects of multiple environmental exposures.

The contribution of the exposome to the burden of cardiovascular disease

Large epidemiological and health impact assessment studies at the global scale, such as the Global Burden of Disease project, indicate that chronic non-communicable diseases, such as atherosclerosis and diabetes mellitus, caused almost two-thirds of the annual global deaths in 2020. By 2030, 77% of all deaths are expected to be caused by non-communicable diseases. Although this increase is mainly due to the ageing of the general population in Western societies, other reasons include the increasing effects of soil, water, air and noise pollution on health, together with the effects of other environmental risk factors such as climate change, unhealthy city designs (including lack of green spaces), unhealthy lifestyle habits and psychosocial stress. The exposome concept was established in 2005 as a new strategy to study the effect of the environment on health. The exposome describes the harmful biochemical and metabolic changes that occur in our body owing to the totality of different environmental exposures throughout the life course, which ultimately lead to adverse health effects and premature deaths. In this Review, we describe the exposome concept with a focus on environmental physical and chemical exposures and their effects on the burden of cardiovascular disease. We discuss selected exposome studies and highlight the relevance of the exposome concept for future health research as well as preventive medicine. We also discuss the challenges and limitations of exposome studies.

Impact of the exposome on cardiovascular disease

Air pollution, noise pollution, and light pollution have emerged as important but often overlooked risk factors for cardiovascular disease. In this review, we examine the emerging concept of the exposome, highlighting the close relationship between environmental exposure (e.g. PM_2.5, traffic noise, and night light) and cardiovascular disease, finally addressing the possible mitigation strategies that should be implemented to reduce the impact of air, noise, and light pollution on cardiovascular morbidity and mortality.

PM2.5 and Cardiovascular Health Risks

PM2.5 is a frequently studied particulate matter metric, due to its wide range of identified overall adverse health effects, particularly cardiovascular health risks. However, there are no clear clinical practice guidelines for air pollution in regard to the prevention of cardiovascular health risks, since most of the current medical guidelines for CVD focus on metabolic risk factors such as hyperlipidemia or diabetes. We sought to determine the relationship between PM2.5 and cardiovascular disease, cardiovascular events, and all-cause mortality by performing a systematic review and meta-analysis. We searched Ovid MEDLINE, Ovid Embase, Ovid Cochrane Database of Systematic Reviews, Scopus, and Web of Science from the database inception to December 2022 for studies that reported an association between PM2.5 and cardiovascular disease, cardiovascular events, and all-cause mortality. We used the DerSimonian & Laird random-effects method to pool hazard ratios or risk ratios separately from the included studies. Of the total 18 prospective studies, 7,300,591 individuals were followed for a median follow-up of 9 years. Compared to low long-term exposure to PM 2.5 levels, an increase in exposure to PM 2.5 levels resulted in an increase in all-cause mortality (HR 1.08 95% CI of 1.05-1.11, P < 0.05). Similarly, when compared to a low long-term exposure to PM 2.5 levels, an increase in exposure to PM 2.5 levels resulted in an increase in cardiovascular disease (HR 1.09, 95% CI of 1.00-1.18, P < 0.05) and an increase in cardiovascular disease mortality (HR 1.12, 95% CI of 1.07-1.18, P < 0.05). Increased exposure to PM 2.5 levels is significantly associated with an increased risk of all-cause mortality, cardiovascular disease, and cardiovascular disease mortality. Although federal primary and secondary standards are in place, those standards are not low enough to prevent CVD health effects. Clinicians should emphasize PM2.5 as a modifiable CV risk factors for their patients to potentially reduce the development of CV complications. A clinical action guideline is needed specifically for air pollution effects on CVD, and how to mitigate them.

BMAL1/p53 mediating bronchial epithelial cell autophagy contributes to PM2.5-aggravated asthma

BACKGROUND

Fine particulate matter (PM2.5) is associated with increased incidence and severity of asthma. PM2.5 exposure disrupts airway epithelial cells, which elicits and sustains PM2.5-induced airway inflammation and remodeling. However, the mechanisms underlying development and exacerbation of PM2.5-induced asthma were still poorly understood. The aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a major circadian clock transcriptional activator that is also extensively expressed in peripheral tissues and plays a crucial role in organ and tissue metabolism.

RESULTS

In this study, we found PM2.5 aggravated airway remodeling in mouse chronic asthma, and exacerbated asthma manifestation in mouse acute asthma. Next, low BMAL1 expression was found to be crucial for airway remodeling in PM2.5-challenged asthmatic mice. Subsequently, we confirmed that BMAL1 could bind and promote ubiquitination of p53, which can regulate p53 degradation and block its increase under normal conditions. However, PM2.5-induced BMAL1 inhibition resulted in up-regulation of p53 protein in bronchial epithelial cells, then increased-p53 promoted autophagy. Autophagy in bronchial epithelial cells mediated collagen-I synthesis as well as airway remodeling in asthma.

CONCLUSIONS

Taken together, our results suggest that BMAL1/p53-mediated bronchial epithelial cell autophagy contributes to PM2.5-aggravated asthma. This study highlights the functional importance of BMAL1-dependent p53 regulation during asthma, and provides a novel mechanistic insight into the therapeutic mechanisms of BMAL1. Video Abstract.

Impact of air pollution on ischemic heart disease: Evidence, mechanisms, clinical perspectives

Ambient air pollution, and especially particulate matter (PM) air pollution <2.5 μm in diameter (PM_2.5), has clearly emerged as an important yet often overlooked risk factor for atherosclerosis and ischemic heart disease (IHD). In this review, we examine the available evidence demonstrating how acute and chronic PM_2.5 exposure clinically translates into a heightened coronary atherosclerotic burden and an increased risk of acute ischemic coronary events. Moreover, we provide insights into the pathophysiologic mechanisms underlying PM_2.5-mediated atherosclerosis, focusing on the specific biological mechanism through which PM_2.5 exerts its detrimental effects. Further, we discuss about the possible mechanisms that explain the recent findings reporting a strong association between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, increased PM_2.5 exposure, and morbidity and mortality from IHD. We also address the possible mitigation strategies that should be implemented to reduce the impact of PM_2.5 on cardiovascular morbidity and mortality, and underscoring the strong need of clinical trials demonstrating the efficacy of specific interventions (including both PM_2.5 reduction and/or specific drugs) in reducing the incidence of IHD. Finally, we introduce the emerging concept of the exposome, highlighting the close relationship between PM_2.5 and other environmental exposures (i.e.: traffic noise and climate change) in terms of common underlying pathophysiologic mechanisms and possible mitigation strategies.

PM2.5 induces the abnormal lipid metabolism and leads to atherosclerosis via Notch signaling pathway in rats

PM_2.5 can affect the lipid metabolism and cause atherosclerosis. Abnormal lipid metabolism is a sever risk factor of atherosclerosis and the underlying molecular mechanism still remains unclear. In this study, GPL16956 Agilent-045997 Arraystar human lncRNA microarray V3 (Probe Name Version) platform was used to detect the different genes of lipid metabolism between the normal arterial intima and advanced atherosclerotic plaque, which were downloaded from GEO database. A high-fat diet and vitamin D3 were administered to Wistar rats to establish the atherosclerotic model and another normal healthy 56 rats were used as the non-atherosclerotic exposure groups. The atherosclerotic rats and non-atherosclerotic rats were randomly divided into 4 PM_2.5 groups (0, 1.5, 7.5, 37.5 mg/kg), respectively. The results of bioinformatics showed changes in the Notch1, Dll1, Hes1, LDLR and ABCG1 levels. PM_2.5 exposure could produce damage to the physiological structure of the aorta, and aggravate atherosclerosis in rats from both non-atherosclerotic and atherosclerotic groups. With the increase of the exposure dose, the levels of TC and TG significantly increased. PM_2.5 exposure significantly affected the expression levels of PPARγ, ABCA1, LDLR, CD36, SR-BI and SREBP2. PM_2.5 exposure could also affect the expression levels of the Notch signaling pathways which was significantly correlated with the levels of TC and TG. The results proved that PM_2.5 exposure could induce and aggravate the atherosclerosis in rats by disrupting lipid metabolism in which Notch signaling pathway may play a significant role.

Climate change and cardiovascular disease: implications for global health

Climate change is the greatest existential challenge to planetary and human health and is dictated by a shift in the Earth's weather and air conditions owing to anthropogenic activity. Climate change has resulted not only in extreme temperatures, but also in an increase in the frequency of droughts, wildfires, dust storms, coastal flooding, storm surges and hurricanes, as well as multiple compound and cascading events. The interactions between climate change and health outcomes are diverse and complex and include several exposure pathways that might promote the development of non-communicable diseases such as cardiovascular disease. A collaborative approach is needed to solve this climate crisis, whereby medical professionals, scientific researchers, public health officials and policymakers should work together to mitigate and limit the consequences of global warming. In this Review, we aim to provide an overview of the consequences of climate change on cardiovascular health, which result from direct exposure pathways, such as shifts in ambient temperature, air pollution, forest fires, desert (dust and sand) storms and extreme weather events. We also describe the populations that are most susceptible to the health effects caused by climate change and propose potential mitigation strategies, with an emphasis on collaboration at the scientific, governmental and policy levels.

Association between fine particulate matter and coronary heart disease: A miRNA microarray analysis

Several studies have reported an association between residential surrounding particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5) and coronary heart disease (CHD). However, the underlying biological mechanism remains unclear. To fill this research gap, this study enrolled a residentially stable sample of 942 patients with CHD and 1723 controls. PM_2.5 concentration was obtained from satellite-based annual global PM_2.5 estimates for the period 1998-2019. MicroRNA microarray and pathway analysis of target genes was performed to elucidate the potential biological mechanism by which PM_2.5 increases CHD risk. The results showed that individuals exposed to high PM_2.5 concentrations had higher risks of CHD than those exposed to low PM_2.5 concentrations (odds ratio = 1.22, 95% confidence interval: 1.00, 1.47 per 10 μg/m³ increase in PM_2.5). Systolic blood pressure mediated 6.6% of the association between PM_2.5 and CHD. PM_2.5 and miR-4726-5p had an interaction effect on CHD development. Bioinformatic analysis demonstrated that miR-4726-5p may affect the occurrence of CHD by regulating the function of RhoA. Therefore, individuals in areas with high PM_2.5 exposure and relative miR-4726-5p expression have a higher risk of CHD than their counterparts because of the interaction effect of PM_2.5 and miR-4726-5p on blood pressure.

Particulate matter and ozone might trigger deaths from chronic ischemic heart disease

AIMS

To study the association between short-term exposure to air pollutants and mortality of Chronic Ischemic Heart Disease (CIHD).

METHODS

Using a case-crossover design, we investigated 148,443 CIHD deaths from 2015 to 2020 in Jiangsu Province, China. Exposure to six ambient pollutants, including PM₁₀, PM_2.5, NO₂, CO, SO₂, and O_3, was assessed by extracting daily concentrations from validated 10 km × 10 km pollutant grids at each subject's residential address. A conditional logistic regression approach was used to explore the exposure-response relationship with adjustment for temperature and relative humidity. We calculated the Population Attributable Fractions (PAFs) and the attributable deaths number of CIHD.

RESULTS

An increase of 10 μg/m³ in PM₁₀ and PM_2.5 exposure was associated with a 1.16% (95% CI: 0.85-1.48%) and 1.80% (1.36-2.24%) increase in CIHD mortality, respectively. A threshold value of 123 µg/m³ was identified for the association between O₃ exposure and CIHD mortality. Controlling for PM_2.5, each increase of 10 µg/m³ in O₃ (>threshold) was statistically significantly associated with a 0.94% (0.19-1.71%) increase in CIHD mortality, however there was no association between NO₂, SO₂, CO exposure and CIHD mortality. Reducing PM_2.5, PM₁₀ and O₃ to the WHO air quality guidelines would prevent 6.16% (95% CI: 4.70-7.58%), 4.30% (3.18-5.43%) and 1.29% (0.48-4.20%) of CIHD deaths, respectively. During the warm season, mortality and PAFs of CIHD associated with PM_2.5, PM₁₀, and O₃ were significantly higher.

CONCLUSIONS

Short-term exposure to ambient PM_2.5, PM_10, and O₃ might trigger deaths from CIHD. These findings indicate that the premature deaths of CIHD patients can be alleviated by reducing exposure to polluted air.

Oxidative stress generated by polycyclic aromatic hydrocarbons from ambient particulate matter enhance vascular smooth muscle cell migration through MMP upregulation and actin reorganization

Background

Epidemiological studies have suggested that elevated concentrations of particulate matter (PM) are strongly associated with the incidence of atherosclerosis, however, the underlying cellular and molecular mechanisms of atherosclerosis by PM exposure and the components that are mainly responsible for this adverse effect remain to be established. In this investigation, we evaluated the effects of ambient PM on vascular smooth muscle cell (VSMC) behavior. Furthermore, the effects of polycyclic aromatic hydrocarbons (PAHs), major components of PM, on VSMC migration and the underlying mechanisms were examined.

Results

VSMC migration was significantly increased by treatment with organic matters extracted from ambient PM. The total amount of PAHs contained in WPM was higher than that in SPM, leading to higher ROS generation and VSMC migration. The increased migration was successfully inhibited by treatment with the anti-oxidant, N-acetyl-cysteine (NAC). The levels of matrix metalloproteinase (MMP) 2 and 9 were significantly increased in ambient PM-treated VSMCs, with MMP9 levels being significantly higher in WPM-treated VSMCs than in those treated with SPM. As expected, migration was significantly increased in all tested PAHs (anthracene, ANT; benz(a)anthracene, BaA) and their oxygenated derivatives (9,10-Anthraquinone, AQ; 7,12-benz(a)anthraquinone, BAQ, respectively). The phosphorylated levels of focal adhesion kinase (FAK) and formation of the focal adhesion complex were significantly increased in ambient PM or PAH-treated VSMCs, and these effects were blocked by administration of NAC or α-NF, an inhibitor of AhR, the receptor that allows PAH uptake. Subsequently, the levels of phosphorylated Src and NRF, the downstream targets of FAK, were altered with a pattern similar to that of p-FAK.

Conclusions

PAHs, including oxy-PAHs, in ambient PM may have dual effects that lead to an increase in VSMC migration. One is the generation of oxidative stress followed by MMP upregulation, and the other is actin reorganization that results from the activation of the focal adhesion complex.

Shengmai Yin alleviated plaque vulnerability and ischemic myocardial damage in diesel exhaust particle-aggravated atherosclerosis with myocardial ischemia

Exposure to diesel exhaust particles (DEP) increases the risk of ischemic heart disease, especially heart attacks and ischemic/thrombotic strokes. Shengmai Yin (SMY) is a traditional Chinese medicine used to treat coronary heart disease. The aim of this study was to determine the protective role of SMY and the mechanism by which SMY affects DEP-induced cardiovascular injury. This study is expected to provide the basis for the development of an adaptive signature of SMY in the prevention of atherosclerotic cardiovascular disease and premature death from global air pollution exposure. We developed animal models of myocardial ischemia and atherosclerosis (AS) in response to DEP exposure. After SMY treatment, serum lipids returned to normal. Aortic plaque area and MMP9 expression were significantly reduced and collagen fiber expression increased after SMY treatment compared to DEP exposure alone. Thus, the risk of plaque formation and vulnerability is reduced. In addition, SMY improved left ventricular structure, morphology, function, blood flow, infarct area, myocardial damage, and ROS accumulation to varying degrees in ApoE-/- mice. These results indicate that the use of SMY is effective, to varying degrees, for the treatment of dyslipidemia, atherosclerosis, myocardial ischemia, and oxidative stress in ApoE-/- mice. SMY has a potential protective effect in DEP-aggravated AS in people with myocardial ischemia.

Association between long-term exposure to air pollution and immune-mediated diseases: a population-based cohort study

Objective

Environmental air pollution has been associated with disruption of the immune system at a molecular level. The primary aim of the present study was to describe the association between long-term exposure to air pollution and risk of developing immune-mediated conditions.

Methods

We conducted a retrospective observational study on a nationwide dataset of women and men. Diagnoses of various immune-mediated diseases (IMIDs) were retrieved. Data on the monitoring of particulate matter (PM)10 and PM2.5 concentrations were retrieved from the Italian Institute of Environmental Protection and Research. Generalised linear models were employed to determine the relationship between autoimmune diseases prevalence and PM.

Results

81 363 subjects were included in the study. We found a positive association between PM10 and the risk of autoimmune diseases (ρ+0.007, p 0.014). Every 10 µg/m³ increase in PM10 concentration was associated with an incremental 7% risk of having autoimmune disease. Exposure to PM10 above 30 µg/m3 and PM2.5 above 20 µg/m³ was associated with a 12% and 13% higher risk of autoimmune disease, respectively (adjusted OR (aOR) 1.12, 95% CI 1.05 to 1.20, and aOR 1.13, 95% CI 1.06 to 1.20). Exposure to PM10 was associated with an increased risk of rheumatoid arthritis; exposure to PM2.5 was associated with an increased risk of rheumatoid arthritis, connective tissue diseases (CTDs) and inflammatory bowel diseases (IBD).

Conclusion

Long-term exposure to air pollution was associated with higher risk of developing autoimmune diseases, in particular rheumatoid arthritis, CTDs and IBD. Chronic exposure to levels above the threshold for human protection was associated with a 10% higher risk of developing IMIDs.

Association of household solid fuel use and long-term exposure to PM2.5 with arthritis in middle-aged and older population in China: A cohort study

Air pollutants are common modifiable risk factors for arthritis. To explore the longitudinal effects of air pollution on arthritis based on a cohort study in middle-aged and elder people of China. Data was obtained from the China Health and Retirement Longitudinal Study (CHARLS) from 2011 to 2018. A total of 7449 participants aged 45 years and older were involved in our study. The generalized linear mixed models were conducted to examine the separate and joint effects of household air pollution and outdoor air pollution on arthritis, respectively. We found a strong significant association between air pollution and arthritis incidence. Individuals cooking primarily with solid fuel were more likely in higher risk of arthritis compared with cleaner fuel (OR= 1.15; 95% CI: 1.08-1.23). The group-based trajectory model identified four trajectory groups, compared with group "High-Decreasing rapidly", adjusted ORs of incident arthritis for group "Middle-Decreasing moderately", "Low-Decreasing slowly" and "Low-Stably" were 1.36 (95% CI, 1.03-1.79), 1.36 (95% CI, 1.01-1.83) and 1.81 (95% CI, 1.30-2.52), respectively. These associations were generally higher in participants younger than 65 years. In addition, solid fuel use and PM2.5 exposure had additive and multiplicative effects on arthritis. The results suggested that solid fuel use and long-term PM2.5 exposure were associated with a higher incidence of arthritis. Therefore, it is necessary to restrict solid fuel use to reduce household air pollution and make stronger environmental protection policies to reduce PM2.5 concentration.

Diesel particulate matter exposure deteriorates cardiovascular health and increases the sensitivity of rat heart towards ischemia reperfusion injury via suppressing mitochondrial bioenergetics function

Documents from previous studies do not sufficiently explain the pathophysiological alterations involved in rat hearts exposed to PM2.5 from diesel exhaust, termed as Diesel Particulate matter (DPM). In the present study, we explored the cardiovascular effect of DPM exposure on the recovery of heart from Ischemia reperfusion injury (IR) and explored the probable cause-effect relationship. Two groups of female Wistar rats were exposed to 0.5 mg/ml DPM for 1 h and 3 h durations daily for 21 days via a whole-body exposure system. At the end of 21st day, the animals were sacrificed and the heart was subjected to IR via Langendorff isolated rat heart perfusion system. 21 days of exposure altered cardiac electrophysiology and the ultra-structure of myocardium. Also, the same group of animals exhibited calcification in the vasculature. These changes were prominent in animals exposed to DPM for 3 h daily. Administration of DPM to H9C2 cells resulted in 15% and 36% cell death after 1hr and 3hrs of incubation, respectively. When the hearts were challenged to IR, both 1 h and 3 h exposed hearts exhibited a significant decline in IR recovery. At the sub-cellular level, DPM exposure reduced ATP levels, mitochondrial copy number, and increased oxidative stress after IR in both exposure groups. These changes were markedly seen in the interfibrillar mitochondrial fraction of the mitochondria. Hence, we conclude that exposure to PM2.5 from diesel exhaust alters electrophysiology and ultrastructure of heart and reduces the level of cellular mediators, thereby compromising the ability of heart to withstand IR injury.

Di(2-ethylhexyl) phthalate (DEHP) and thyroid: biological mechanisms of interference and possible clinical implications

Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental endocrine disruptor. DEHP can be absorbed into the human body through the air, food, water, and skin. After entering the human body, DEHP is rapidly converted to mono(2-ethylhexyl) phthalate (MEHP) with greater toxicity than DEHP. An increasing number of studies indicates that DEHP or MEHP can damage the thyroid tissue and disrupt the function, but the mechanisms remain unclear. This article reviews the toxicity of DEHP on thyroid structures and functions and summarizes the potential mechanisms to provide evidence for preventing the thyroid-related diseases.

PM2.5 promoted lipid accumulation in macrophage via inhibiting JAK2/STAT3 signaling pathways and aggravating the inflammatory reaction

BACKGROUND

Abnormal lipid accumulation in macrophages may lead to macrophages foaming, which is the most important pathological process of atherosclerosis. Atmospheric PM_2.5 could enter the blood circulation and further affect the lipid metabolism of macrophages. But the underlying mechanism is not unclear. This study was undertaken to clarify the effect of PM_2.5 on lipid metabolism in macrophages, and to explore the role of inflammatory reaction and JAK2/STAT3 signaling pathway in this process.

METHOD

Macrophages derived from THP-1 cells were exposed to PM_2.5 (0,100,200,400 μg/mL) for 6 h and 12 h. STAT3 agonist ColivelinTFA is used to specifically excite STAT3. The survival rate of macrophages was detected by CCK-8. The lipid levels in macrophages were detected by colorimetry. The levels of inflammatory factors secreted by macrophages were detected by ELISA. Q-PCR was used to detect the mRNA expression levels, and Western Blot was used to detect the protein expression levels of JAK2/STAT3 pathway genes.

RESULT

The survival rate of macrophages was reduced by PM_2.5, and the levels of TG, T-CHO and LDL-C of macrophages exposed to PM_2.5 were increased. PM_2.5 led to the increasing level of IL-6 and the decreasing level of IL-4, and the JAK2/STAT3 signaling pathway was inhibited by PM_2.5. Colivelin TFA significantly decreased the increasing levels of TG, T-CHO and LDL-C levels, and increased the decreasing mRNA levels of IL-4, and LPL induced by PM_2.5 (p < 0.05).

DISCUSSION

PM_2.5 could cause the lipid accumulation of macrophages by inhibiting the JAK2/STAT3 signaling pathway, and inflammatory responses may be involved in this process.

Cumulative exposure amount of PM2.5 in the ambient air is associated with coronary atherosclerosis - Serial coronary CT angiography study

BACKGROUND

We investigated the change of coronary atherosclerosis with long-term exposure to fine particulate matter of aerodynamic diameter <2.5 ​μm (PM_2.5) using coronary computed tomography angiography (CCTA).

METHODS

Subjects undergoing serial CCTAs between January 2007 and December 2017 (n ​= ​3,127) were analyzed. Each individual's cumulative amount of PM_2.5 exposure between the two CCTAs was evaluated by Kriging interpolation and zonal analysis, considering the time interval between the two CCTAs. The main outcome was progression of coronary artery calcium (CAC) with additional semiquantitative analysis on the changes in the severity and composition of atherosclerotic plaques.

RESULTS

The CAC scores increased by 30.8 Agatston units per-year under a median PM_2.5 concentration 24.9 ​μg/m³ and tended to increase with the cumulative amount of PM_2.5 exposure (r ​= ​0.321, p ​<0.001). The CAC progressed in 1,361 (43.5%) subjects during a median 53 months follow-up. The cumulative amount of PM_2.5 exposure was independently associated with CAC progression (adjusted OR 1.09, p ​<0.001). By random forest analysis, the relative impact of cumulative amount of PM_2.5 exposure on CAC progression was higher than that of traditional cardiovascular risk factors and the average concentration of PM_2.5. The extent of coronary atherosclerosis and newly developed calcified plaque on follow-up were also significantly associated with the cumulative amount of PM_2.5 exposure.

CONCLUSIONS

Cumulative exposure to air pollution is associated with the progression of diffuse coronary calcification, the importance of which may be more significant than other traditional cardiovascular risk factors. Further investigations into the causality between PM_2.5 and coronary atherosclerosis are warranted to improve global cardiovascular health.

Physical Activity in Polluted Air-Net Benefit or Harm to Cardiovascular Health? A Comprehensive Review

Both exposure to higher levels of polluted air and physical inactivity are crucial risk factors for the development and progression of major noncommunicable diseases and, in particular, of cardiovascular disease. In this context, the World Health Organization estimated 4.2 and 3.2 million global deaths per year in response to ambient air pollution and insufficient physical activity, respectively. While regular physical activity is well known to improve general health, it may also increase the uptake and deposit of air pollutants in the lungs/airways and circulation, due to increased breathing frequency and minute ventilation, thus increasing the risk of cardiovascular disease. Thus, determining the tradeoff between the health benefits of physical activity and the potential harmful effects of increased exposure to air pollution during physical activity has important public health consequences. In the present comprehensive review, we analyzed evidence from human and animal studies on the combined effects of physical activity and air pollution on cardiovascular and other health outcomes. We further report on pathophysiological mechanisms underlying air pollution exposure, as well as the protective effects of physical activity with a focus on oxidative stress and inflammation. Lastly, we provide mitigation strategies and practical recommendations for physical activity in areas with polluted air.

Role of miR-145-5p/ CD40 in the inflammation and apoptosis of HUVECs induced by PM2.5

Fine particulate matter (PM_2.5) exposure can cause the injury of vascular endothelial cells by inflammatory response. CD40 works in inflammation of endothelial cells and it may be regulated by the miRNAs. This study aimed to clarify the role and mechanism of CD40 and miR-145-5p in PM_2.5-induced injury of human umbilical vein endothelial cells (HUVECs). HUVECs were treated with different concentrations of PM_2.5 exposure (0, 100, 200, 400 μg/mL) for 24 h. The si-RNA was used for CD40 gene silencing (0, 200 μg/mL PM_2.5, siRNA-CD40 and siRNA-CD40 + 200 μg/mL PM_2.5). Mimics was used for overexpression of miR-145-5p (0, 200 μg/mL PM_2.5, mimics and mimics+200 μg/mL PM_2.5). The cell viability of HUVECs was detected with Cell Counting Kit8 (CCK8) kit. The level of cell apoptosis was detected by flow cytometry. The inflammation-related factor including interleukin-1β (IL-1β), interleukin-18 (IL-18), tumor necrosis factor α (TNF-α) and C1q complement/tumor necrosis factor (TNF)-associated proteins9 (CTRP9) were tested with enzyme-linked immunosorbent assay (ELISA) kits. The mRNA and protein expression levels of CD40, CD40L, caspase1, NLRP3 (Nod-like receptor family pyrin domain-containing 3) and IKKB were detected with quantitative real-time PCR (qRT-PCR), Western blot and Immunofluorescence. Compared with the control group, the cell viability of HUVECs exposed to PM_2.5 was significantly decreased (p < 0.05); the levels of IL-Iβ and TNF-α were significantly increased, while the level of CTRP9 was significantly decreased (p < 0.05). The proportion of apoptotic cells was increased after being treated with PM_2.5 (p < 0.05). Besides, the mRNA and protein levels of CD40, CD40L, IKKB, NLRP3 and caspase1 were increased comparing with the control group (p < 0.05). After CD40 silencing, the condition of inflammation and apoptosis in HUVECs exposed to PM_2.5 was alleviated, and the expression levels of CD40L, IKKB, NLRP3 and caspase1 were significantly decreased (p < 0.05). Furthermore, miR-145-5p was significantly down-regulated after exposure to 200μg/mL PM_2.5 (p < 0.05). After over-expression of miR-145-5p, the expression level of CD40 was decreased (p < 0.05). Taken together, PM_2.5 can cause inflammation and apoptosis of HUVECs via the activation of CD40, which can be regulated by miR-145-5p. Over-expression of miR-145-5p can down-regulate CD40, further inhibiting the inflammation and apoptosis of HUVECs induced by PM_2.5.

Air Pollution and Coronary Plaque Vulnerability and Instability: An Optical Coherence Tomography Study

OBJECTIVES

We assessed the relationship between exposure to air pollutants and mechanisms of coronary instability evaluated by optical coherence tomography (OCT) in patients with acute coronary syndrome (ACS).

BACKGROUND

Air pollution is an emerging key player in determining the residual risk of coronary events. However, pathophysiological mechanisms linking air pollution and coronary events have been not adequately investigated.

METHODS

Patients with ACS undergoing OCT imaging were retrospectively selected. Mechanism of culprit lesion instability was classified as plaque rupture (PR) or intact fibrous cap (IFC) by OCT, and the presence of macrophage infiltrates (MØI) and thin-cap fibroatheroma (TCFA) at the culprit site was also assessed. Based on each case's home address, exposure to several pollutants was evaluated, including particulate matter 2.5 (PM2.5), PM10, and carbon monoxide (CO). Only patients with >2 years of available data on air pollution exposure prior to ACS were enrolled.

RESULTS

We included 126 patients (median age: 67.0 years of age; interquartile range: 55.5-76.0; 97 male patients [77.0%]). Sixty-six patients (52.4%) had PR as the mechanism of plaque instability. Patients with PR were exposed to significantly higher PM2.5 levels than to IFC, and PM2.5 was independently associated with PR (odds ratio: 1.194; 95% CI: 1.036 to 1.377; P = 0.015). Moreover, exposure to higher levels of PM2.5 was independently associated with the presence of TCFA and of MØI at the culprit site. Interestingly, PM2.5, PM10, and Co levels were positively and significantly correlated with serum levels of C-reactive protein.

CONCLUSIONS

We provide novel insights into the missing link between air pollution and increased risk of coronary events. In particular, exposure to higher concentrations of air pollutants is associated with the presence of vulnerable plaque features and with plaque rupture as a mechanism of coronary instability. An enhanced systemic and plaque inflammatory activation may explain these findings.

Environmental risk factors and cardiovascular diseases: a comprehensive review

Noncommunicable diseases (NCDs) are fatal for more than 38 million people each year and are thus the main contributors to the global burden of disease accounting for 70% of mortality. The majority of these deaths are caused by cardiovascular disease. The risk of NCDs is strongly associated with exposure to environmental stressors such as pollutants in the air, noise exposure, artificial light at night and climate change, including heat extremes, desert storms and wildfires. In addition to the traditional risk factors for cardiovascular disease such as diabetes, arterial hypertension, smoking, hypercholesterolemia and genetic predisposition, there is a growing body of evidence showing that physicochemical factors in the environment contribute significantly to the high NCD numbers. Furthermore, urbanization is associated with accumulation and intensification of these stressors. This comprehensive expert review will summarize the epidemiology and pathophysiology of environmental stressors with a focus on cardiovascular NCDs. We will also discuss solutions and mitigation measures to lower the impact of environmental risk factors with focus on cardiovascular disease.

A traditional herbal formula, Deng-Shi-Qing-Mai-Tang, regulates TLR4/NF-κB signaling pathway to reduce inflammatory response in PM2.5-induced lung injury

BACKGROUND

Studies revealed that particulate matter 2.5 (PM2.5) enters the lung through the respiratory tract and can damage lung tissue resulting in lung injury primarily via imbalance between pro-inflammatory and anti-inflammatory responses. Moreover, TLR4/NF-κB signaling pathways are reported to play a role in PM2.5-induced inflammation and lung injury, which is closely related to the inflammatory responses. Therefore, the traditional herbal formula, Deng-Shi-Qing-Mai-Tang (DSQMT), has been applied to improve patients' clinical symptoms with lung injury induced by PM2.5. It can reduce inflammatory reactions in lung injury and relieve cough and phlegm. However, the underlying mechanism of DSQMT treatment is still exclusive.

PURPOSE

To clarify the preventive and therapeutic effects of DSQMT on PM2.5-induced lung injury and explore its underlying mechanism.

STUDY DESIGN

PM2.5-induced lung injury rat model was established, and DSQMT was administered.

METHODS

First, PM2.5 was collected, and PM2.5 suspension was prepared. Then, a rat model with PM2.5-induced lung injury was established, and the effects of DSQMT were evaluated in vivo. Finally, the roles of DSQMT in inhibiting the TLR4/NF-κB signaling pathway were investigated in vitro using the NR8383 cell line via Western blot analysis, real-time PCR, electrophoretic mobility shift assay (EMSA), and immunofluorescence staining, respectively and analyzed.

RESULTS

We found that DSQMT significantly attenuated pathological lung tissue damage and inflammatory responses in PM2.5-induced lung injury. We also found that after PM2.5 stimulation in vitro, DSQMT regulates the expression of TLR4, MyD88, IKK, IκB-α, NF-κB p65 in the TLR4/NF-κB signaling pathway. It also constrains activated NF-κB entry into the nucleus and further limits its binding to target DNA. In addition, we revealed that DSQMT down-regulated interleukin (IL)-1β, IL-6, IL-10, THF-α, NO, PGE₂ to reduce the inflammatory response.

CONCLUSION

We demonstrated that DSQMT has preventive and therapeutic effects on PM2.5-induced lung injury by down-regulation of the TLR4/NF-κB signaling pathway. Therefore, the efficacy of traditional Chinese medicine (TCM) in PM2.5 lung injury can be taken into consideration and may be improved in the future through further researches.

Air pollution and cardiovascular disease: Can the Australian bushfires and global COVID-19 pandemic of 2020 convince us to change our ways?

Air pollution is a major global challenge for a multitude of reasons. As a specific concern, there is now compelling evidence demonstrating a causal relationship between exposure to airborne pollutants and the onset of cardiovascular disease (CVD). As such, reducing air pollution as a means to decrease cardiovascular morbidity and mortality should be a global health priority. This review provides an overview of the cardiovascular effects of air pollution and uses two major events of 2020-the Australian bushfires and COVID-19 pandemic lockdown-to illustrate the relationship between air pollution and CVD. The bushfires highlight the substantial human and economic costs associated with elevations in air pollution. Conversely, the COVID-19-related lockdowns demonstrated that stringent measures are effective at reducing airborne pollutants, which in turn resulted in a potential reduction in cardiovascular events. Perhaps one positive to come out of 2020 will be the recognition that tough measures are effective at reducing air pollution and that these measures have the potential to stop thousands of deaths from CVD.

Ambient Air Pollution and Atherosclerosis: Recent Updates

Purpose of Review

During the past century, exposure to particulate matter (PM) air pollution < 2.5 μm in diameter (PM_2.5) has emerged as an all-pervading element of modern-day society. This increased exposure has come at the cost of heightened risk for cardiovascular (CV) morbidity and mortality. Not only can short-term PM_2.5 exposure trigger acute CV events in susceptible individuals, but longer-term exposure over years augments CV risk to a greater extent in comparison with short-term exposure. The purpose of this review is to examine the available evidence for how ambient air pollution exposure may precipitate events at various time frames.

Recent Findings

Recent epidemiological studies have demonstrated an association between ambient PM_2.5 exposure and the presence and progression of atherosclerosis in humans. Multiple animal exposure experiments over two decades have provided strong corroborative evidence that chronic exposure in fact does enhance the progression and perhaps vulnerability characteristics of atherosclerotic lesions.

Summary

Evidence from epidemiological studies including surrogates of atherosclerosis, human translational studies, and mechanistic investigations utilizing animal studies have improved our understanding of how ambient air pollution may potentiate atherosclerosis and precipitate cardiovascular events. Even so, future research is needed to fully understand the contribution of different constituents in ambient air pollution–mediated atherosclerosis as well as how other systems may modulate the impact of exposure including adaptive immunity and the gut microbiome. Nevertheless, due to the billions of people continually exposed to PM_2.5, the long-term pro-atherosclerotic effects of this ubiquitous air pollutant are likely to be of enormous and growing global public health importance.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11883-021-00958-9.

Role of atmospheric particulate matter exposure in COVID-19 and other health risks in human: A review

Due to intense industrialization and urbanization, air pollution has become a serious global concern as a hazard to human health. Epidemiological studies found that exposure to atmospheric particulate matter (PM) causes severe health problems in human and significant damage to the physiological systems. In recent days, PM exposure could be related as a carrier for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus transmission and Coronavirus disease 2019 (COVID-19) infection. Hence, it is important to understand the adverse effects of PM in human health. This review aims to provide insights on the detrimental effects of PM in various human health problems including respiratory, circulatory, nervous, and immune system along with their possible toxicity mechanisms. Overall, this review highlights the potential relationship of PM with several life-limiting human diseases and their significance for better management strategies.

Shenlian extract protects against ultrafine particulate matter-aggravated myocardial ischemic injury by inhibiting inflammation response via the activation of NLRP3 inflammasomes

Air pollution is a growing public health burden associated with several negative health effects, especially cardiovascular disease. Shenlian extract (SL), a traditional Chinese medicine, has the effects of clearing heat-toxin and promoting blood circulation for removing blood stasis, and it has long been used to treat cardiovascular diseases and atherosclerosis. This study explored the underlying action mechanism of SL against ultrafine particle-induced myocardial ischemic injury (UFP-MI) through network pharmacology prediction and experimental verification. Male Sprague-Dawley rats with UFP-MI were pre-treated with SL intragastrically for 7 days. All the rats were then euthanized. Inflammatory cytokine detection and histopathological analysis were performed to assess the protective effects of SL. For the mechanism study, differentially expressed genes (DEGs) were identified in UFP-MI rats treated with SL through transcriptomic analysis. Subsequently, in combination with network pharmacology, potential pathways involved in the effects of SL treatment were identified using the Internet-based Computation Platform (www.tcmip.cn) and Cytoscape 3.6.0. Further validation experiments were performed to reveal the mechanism of the therapeutic effects of SL on UFP-MI. The results show that SL significantly suppressed inflammatory cell infiltration into myocardial tissue and exhibited significant anti-inflammatory activity. Transcriptomic analysis revealed that the DEGs after SL treatment had significant anti-inflammatory, immunomodulatory, and anti-viral activities. Network pharmacology analysis illustrated that the targets of SL were mainly involved in regulation of the inflammatory response, apoptotic process, innate immune response, platelet activation, and coagulation process. By combining transcriptomic and network pharmacology data, we found that SL may exert anti-inflammatory effects by acting on the NOD-like signaling pathway to regulate immune response activation and inhibit systemic inflammation. Verification experiments revealed that SL can suppress the secretion of the inflammatory cytokines Interleukin-1 (IL-1), Interleukin-18(IL-18) and Interleukin-33(IL-33) and suppress NLRP3 inflammasome activity. The results suggested that SL can directly inhibit the activation of NLRP3 inflammasomes and reduce the release of cytokines to protect against ultrafine particulate matter-aggravated myocardial ischemic injury.

Predictive value of spiral shape in coronary plaque progression: an intraindividual comparative study

OBJECTIVE

We conducted a pilot study to explore the value of spiral-shaped sign of plaque from coronary computed tomographic angiography (CCTA) in predicting plaque progression by intraindividual comparison.

METHODS

A total of 30 patients with a total of 60 plaques who received serial CCTA were retrospectively included and intraindividual compared. The spiral shape was defined as plaques coursing along the long axis of a coronary artery and encircling it at an angle of ≥ 180 degrees. The high-risk and other plaque signs were recorded.

RESULTS

On baseline CCTA, the spiral shape (P < 0.01) and length (P < 0.05) of plaques were more frequently seen in the progression group than in the nonprogression group; however, there was no difference between two groups in terms of high-risk plaque signs. In the progression group, plaque length, volume, and napkin-ring sign on follow-up CCTA were significantly greater than at baseline (P < 0.05). In the nonprogression group, there were fewer low-attenuation and positive remodeling plaques on follow-up CCTA than at baseline (P < 0.05). The spiral shape (standardized β = -4.55; P < 0.01) was an independent risk factor for plaque progression. There were 24 spiral plaques in the progression group, of which 16 (66.7%) had progression below the twist point of the spiral shape.

CONCLUSIONS

The baseline spiral shape is more frequently found in those lesions that progress than in those that do not in patients with multiple coronary lesions, and the spiral shape is an independent predictor of which plaques will progress.

Effects of Real-Ambient PM2.5 Exposure on Lung Damage Modulated by Nrf2-/

Previous studies have shown that long-term exposure to fine particulate matter (PM_2.5) increases the morbidity and mortality of pulmonary diseases such as asthma, chronic obstructive pulmonary disease and pulmonary emphysema. Oxidative stress and inflammation play key roles in pulmonary damage caused by PM_2.5. Nuclear factor erythroid 2-related factor 2 (Nrf2) could regulate the expression of antioxidant and anti-inflammatory genes and is pivotal for protection against PM_2.5-induced oxidative stress. In this study, a real-ambient exposure system was constructed with the outdoor ambient air in north China. Wild-type (WT) and Nrf2^−/− (KO) mice were exposed to the real-ambient system for six weeks. After PM_2.5 exposure, our data showed that the levels of inflammatory factors and malondialdehyde were significantly increased in WT and KO mice. Moreover, the lung function and pathological phenotype of the WT mice were altered but there was no obvious change in the Nrf2^−/− mice. To further explore the potential molecular mechanisms, we performed RNA-sequencing. The RNA-sequence analysis results showed that the CYP450 pathway in the first ten pathways of KEGG was related to the metabolism of PM_2.5. In WT and KO mice, the expression of CYP2E1 in the CYP450 pathway showed opposite trends after PM_2.5 exposure. The data showed that the expression of the CYP2E1 gene in WT-PM mice increased while it decreased in KO-PM; the expression of the CYP2E1 protein showed a similar trend. CYP2E1 is primarily distributed in the endoplasmic reticulum (ER) where it could metabolize various exogenous substances attached to PM_2.5 and produce highly toxic oxidation products closely related to ER stress. Consistently, the expression level of GRP94, a biomarker of ER stress, was increased in WT mice and reduced in KO mice under PM_2.5 exposure. Persistent ER stress is a mechanism that causes lung damage under PM_2.5 exposure. Nrf2 facilitates lung injury during PM_2.5 exposure and CYP2E1 metabolism is involved in this process.

The epidemiological trends in the burden of lung cancer attributable to PM2.5 exposure in China

Objective

PM_2.5, which is a major contributor to air pollution, has large effects on lung cancer mortality. We want to analyse the long-term trends in lung cancer burden attributable to PM_2.5 exposure and provide evidence that can be used for preventive measures and health resource planning.

Methods

Mortality data related to lung cancer were obtained from the Global Burden of Disease (GBD) 2019 project. A joinpoint regression analysis was used to assess the magnitude and direction of the trends in mortality from 1990 to 2019, and the age-period-cohort method was used to analyse the temporal trends in the mortality rate of lung cancer attributable to PM_2.5 exposure by age, period, and cohort.

Results

From 1990 to 2019, the age-standardized mortality rate (ASMR) attributable to PM_2.5 exposure trended slowly upwards, and the ASMR due to ambient PM_2.5 exposure (APE) increased significantly, that due to household PM_2.5 exposure (HPE) decreased. The longitudinal age curves show that the mortality rates due to PM_2.5 exposure among younger individuals were low, and they significantly increased from their levels among those in the 45–49 age group to their levels among those in the over-85 age group. From 1990 to 2019, the period RRs due to APE increased, but those due to HPE decreased. Similar trends were observed in the cohort RRs. The overall net drift per year attributable to PM_2.5 exposure was below 0. The local drift values increased with age and were above 0 for the over-80 age groups. The overall net drifts per year were above zero for APE and below zero for HPE. The corresponding results among males were higher than those among females.

Conclusions

In China, the type of air pollution responsible for lung cancer has changed from household air pollution to ambient air pollution. PM_2.5 exposure is more harmful among males and older people. Ambient air pollution should be emphasized, and China should strengthen its implementation of effective public policies and other interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10765-1.

Association of air pollution and greenness with carotid plaque: A prospective cohort study in China

Previous studies indicated that exposure to air pollution was associated with the progress of atherosclerosis, but evidence is very limited in China and even in the world. This study aims to assess the associations of long-term exposures to air pollution and greenness with the occurrence of carotid plaque. Participants of this cohort study were urban residents and office workers who visited Hebei General Hospital for routine physical examination annually from September 2016 through to December 2018. Eligible participants were people diagnosed the absence of carotid plaque clinically at their first hospital visit and were followed up at their second or third hospital visit. Exposure to particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5), nitrogen dioxide (NO2) and ozone (O3) were estimated using an inverse distance weighted (IDW) method. The level of greenness was assessed using the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). The associations were evaluated using Cox proportional hazards regression models. Among 4,137 participants, 575 showed the occurrence of carotid plaque during the follow-up period. After controlling for potential confounders, the hazard ratios (HRs) and 95% confidence intervals (95%CIs) of carotid plaque associated with per interquartile range (IQR) increase in PM2.5, NO2, and O3 were 1.78 (1.55, 2.03), 1.32 (1.14, 1.53) and 1.99 (1.71, 2.31), respectively. Increased EVI and NDVI were significantly associated with lower risk of carotid plaque [HR (and 95%CI): 0.84 (0.77, 0.93) and 0.87 (0.80, 0.94)]. PM2.5 significantly mediated 80.47% or 93.00% of the estimated association between EVI or NDVI and carotid plaque. In light of the significant associations between air pollution, greenness and carotid plaque in this study, continued efforts are needed to curb air pollution and plan more green space considering their effects on vascular disease.

Topological Data Analysis of Coronary Plaques Demonstrates the Natural History of Coronary Atherosclerosis

OBJECTIVES

This study sought to identify distinct patient groups and their association with outcome based on the patient similarity network using quantitative coronary plaque characteristics from coronary computed tomography angiography (CTA).

BACKGROUND

Coronary CTA can noninvasively assess coronary plaques quantitatively.

METHODS

Patients who underwent 2 coronary CTAs at a minimum of 24 months' interval were analyzed (n = 1,264). A similarity Mapper network of patients was built by topological data analysis (TDA) based on the whole-heart quantitative coronary plaque analysis on coronary CTA to identify distinct patient groups and their association with outcome.

RESULTS

Three distinct patient groups were identified by TDA, and the patient similarity network by TDA showed a closed loop, demonstrating a continuous trend of coronary plaque progression. Group A had the least coronary plaque amount (median 12.4 mm³ [interquartile range (IQR): 0.0 to 39.6 mm³]) in the entire coronary tree. Group B had a moderate coronary plaque amount (31.7 mm³ [IQR: 0.0 to 127.4 mm³]) with relative enrichment of fibrofatty and necrotic core (32.6% [IQR: 16.7% to 46.2%] and 2.7% [IQR: 0.1% to 6.9%] of the total plaque, respectively) components. Group C had the largest coronary plaque amount (187.0 mm³ [IQR: 96.7 to 306.4 mm³]) and was enriched for dense calcium component (46.8% [IQR: 32.0% to 63.7%] of the total plaque). At follow-up, total plaque volume, fibrous, and dense calcium volumes increased in all groups, but the proportion of fibrofatty component decreased in groups B and C, whereas the necrotic core portion decreased in only group B (all p < 0.05). Group B showed a higher acute coronary syndrome incidence than other groups (0.3% vs. 2.6% vs. 0.6%; p = 0.009) but both group B and C had a higher revascularization incidence than group A (3.1% vs. 15.5% vs. 17.8%; p < 0.001). Incorporating group information from TDA demonstrated increase of model fitness for predicting acute coronary syndrome or revascularization compared with that incorporating clinical risk factors, percentage diameter stenosis, and high-risk plaque features.

CONCLUSIONS

The TDA of quantitative whole-heart coronary plaque characteristics on coronary CTA identified distinct patient groups with different plaque dynamics and clinical outcomes. (Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography Imaging [PARADIGM]; NCT02803411).

Ambient fine particulate matter aggravates atherosclerosis in apolipoprotein E knockout mice by iron overload via the hepcidin-ferroportin axis

AIMS

Exposure to fine particulate matter (PM2.5) is correlated to atherosclerosis, but the mechanism remains largely undefined. Iron overload is a significant contributor to atherosclerosis, and iron homeostasis is highly regulated by the hepcidin-ferroportin (FPN) axis. Here we aimed to investigate the association between iron overload and PM2.5-induced atherosclerotic mice.

MAIN METHODS

Apolipoprotein E knockout (ApoE-/-) mice were randomly assigned to filtered air (FA group) or PM2.5 (PM2.5 group) for 3-month inhalation. Daily PM2.5 mass concentrations, serum levels of ferritin, iron, pro-atherosclerotic cytokines and lipid profiles, atherosclerotic lesion areas, hepcidin, FPN and iron depositions in atherosclerotic lesions, hepcidin, FPN mRNA and protein expressions in the aorta were detected, respectively.

KEY FINDINGS

The daily average concentration of atmospheric PM2.5 was 68.2 ± 21.8 μg/m3. Serum levels of ferritin, iron, VEGF, MCP-1, IL-6, TNF-α, TC and LDL-C, atherosclerotic lesion areas, hepcidin and iron depositions in atherosclerotic lesions, hepcidin mRNA and protein expressions in the PM2.5 group were observably higher than those in the FA group. Nevertheless, FPN deposition in atherosclerotic lesions, FPN mRNA and protein expressions in the aorta of the PM2.5 group were markedly lower than those of the FA group.

SIGNIFICANCE

PM2.5 inhalation could exacerbate the formation and development of atherosclerosis in ApoE-/- mice, the potential mechanisms may be partly associated with iron overload via the hepcidin-FPN axis, as well as iron-triggered systemic inflammation and hyperlipidemia.

Ambient Air Pollution and Atherosclerosis: Insights Into Dose, Time, and Mechanisms

Ambient air pollution due to particulate matter ≤2.5 μ is the leading environmental risk factor contributing to global mortality, with a preponderant majority of these deaths attributable to atherosclerotic cardiovascular disease (ASCVD) causes such as stroke and myocardial infarction. Epidemiological studies in humans have provided refined estimates of exposure risk, with evidence suggesting that risk association with particulate matter ≤2.5 levels and ASCVD continues at levels well below air quality guidelines in North America and Europe. Mechanistic studies in animals and humans have provided a framework of understanding of the duration and pathways by which air pollution exposure may predispose to atherosclerosis. Although acute exposure to particulate matter ≤2.5 is associated with oxidative stress and inflammation, system transmission of signals from the lungs to extrapulmonary sites may involve direct translocation of components, biologic intermediates, and autonomic nervous system activation. End-organ effector pathways such as endothelial barrier disruption/dysfunction, thrombosis, vasoconstriction/increased blood pressure, and plaque instability, may contribute to ASCVD. The strength of the association of air pollution with ASCVD offers an opportunity to mitigate its consequences. Although elimination of anthropogenic sources of air pollution with a switch to clean energy provides the ultimate solution, this may not be possible in the interim and may require personal protection efforts and an integrated approach to managing risk posed by air pollution for ASCVD.

The critical role of endothelial function in fine particulate matter-induced atherosclerosis

Ambient and indoor air pollution contributes annually to approximately seven million premature deaths. Air pollution is a complex mixture of gaseous and particulate materials. In particular, fine particulate matter (PM2.5) plays a major mortality risk factor particularly on cardiovascular diseases through mechanisms of atherosclerosis, thrombosis and inflammation. A review on the PM2.5-induced atherosclerosis is needed to better understand the involved mechanisms. In this review, we summarized epidemiology and animal studies of PM2.5-induced atherosclerosis. Vascular endothelial injury is a critical early predictor of atherosclerosis. The evidence of mechanisms of PM2.5-induced atherosclerosis supports effects on vascular function. Thus, we summarized the main mechanisms of PM2.5-triggered vascular endothelial injury, which mainly involved three aspects, including vascular endothelial permeability, vasomotor function and vascular reparative capacity. Then we reviewed the relationship between PM2.5-induced endothelial injury and atherosclerosis. PM2.5-induced endothelial injury associated with inflammation, pro-coagulation and lipid deposition. Although the evidence of PM2.5-induced atherosclerosis is undergoing continual refinement, the mechanisms of PM2.5-triggered atherosclerosis are still limited, especially indoor PM2.5. Subsequent efforts of researchers are needed to improve the understanding of PM2.5 and atherosclerosis. Preventing or avoiding PM2.5-induced endothelial damage may greatly reduce the occurrence and development of atherosclerosis.

Effects of air pollution particles (ultrafine and fine particulate matter) on mitochondrial function and oxidative stress - Implications for cardiovascular and neurodegenerative diseases

Environmental pollution is a major cause of global mortality and burden of disease. All chemical pollution forms together may be responsible for up to 12 million annual excess deaths as estimated by the Lancet Commission on pollution and health as well as the World Health Organization. Ambient air pollution by particulate matter (PM) and ozone was found to be associated with an all-cause mortality rate of up to 9 million in the year 2015, with the majority being of cerebro- and cardiovascular nature (e.g. stroke and ischemic heart disease). Recent evidence suggests that exposure to airborne particles and gases contributes to and accelerates neurodegenerative diseases. Especially, airborne toxic particles contribute to these adverse health effects. Whereas it is well established that air pollution in the form of PM may lead to dysregulation of neurohormonal stress pathways and may trigger inflammation as well as oxidative stress, leading to secondary damage of cardiovascular structures, the mechanistic impact of PM-induced mitochondrial damage and dysfunction is not well established. With the present review we will discuss similarities between mitochondrial damage and dysfunction observed in the development and progression of cardiovascular disease and neurodegeneration as well as those adverse mitochondrial pathomechanisms induced by airborne PM.

Aryl hydrocarbon receptor connects dysregulated immune cells to atherosclerosis

As a chronic inflammatory disease with autoimmune components, atherosclerosis is the major cause of cardiovascular morbidity and mortality. Recent studies have revealed that the development of atherosclerosis is strongly linked to the functional activities of aryl hydrocarbon receptor (AHR), a chemical sensor that is also important for the development, maintenance, and function of a variety of immune cells. In this review, we focus on the impact of AHR signaling on the different cell types that are closely related to the atherogenesis, including T cells, B cells, dendritic cells, macrophages, foam cells, and hematopoietic stem cells in the arterial walls, and summarize the latest development on the interplay between this environmental sensor and immune cells in the context of atherosclerosis. Hopefully, elucidation of the role of AHR in atherosclerosis will facilitate the understanding of case variation in disease prevalence and may aid in the development of novel therapies.

Environmental determinants of cardiovascular disease: lessons learned from air pollution

Air pollution is well recognized as a major risk factor for chronic non-communicable diseases and has been estimated to contribute more to global morbidity and mortality than all other known environmental risk factors combined. Although air pollution contains a heterogeneous mixture of gases, the most robust evidence for detrimental effects on health is for fine particulate matter (particles ≤2.5 µm in diameter (PM2.5)) and ozone gas and, therefore, these species have been the main focus of environmental health research and regulatory standards. The evidence to date supports a strong link between the risk of cardiovascular events and all-cause mortality with PM2.5 across a range of exposure levels, including to levels below current regulatory standards, with no 'safe' lower exposure levels at the population level. In this comprehensive Review, the empirical evidence supporting the effects of air pollution on cardiovascular health are examined, potential mechanisms that lead to increased cardiovascular risk are described, and measures to reduce this risk and identify key gaps in our knowledge that could help address the increasing cardiovascular morbidity and mortality associated with air pollution are discussed.

Iron-rich air pollution nanoparticles: An unrecognised environmental risk factor for myocardial mitochondrial dysfunction and cardiac oxidative stress

Exposure to particulate air pollution is a major environmental risk factor for cardiovascular mortality and morbidity, on a global scale. Both acute and chronic cardiovascular impacts have so far been attributed to particulate-mediated oxidative stress in the lung and/or via 'secondary' pathways, including endothelial dysfunction, and inflammation. However, increasing evidence indicates the translocation of inhaled nanoparticles to major organs via the circulation. It is essential to identify the composition and intracellular targets of such particles, since these are likely to determine their toxicity and consequent health impacts. Of potential major concern is the abundant presence of iron-rich air pollution nanoparticles, emitted from a range of industry and traffic-related sources. Bioreactive iron can catalyse formation of damaging reactive oxygen species, leading to oxidative stress and cell damage or death. Here, we identify for the first time, in situ, that exogenous nanoparticles (~15-40 nm diameter) within myocardial mitochondria of young, highly-exposed subjects are dominantly iron-rich, and co-associated with other reactive metals including aluminium and titanium. These rounded, electrodense nanoparticles (up to ~ 10 x more abundant than in lower-pollution controls) are located within abnormal myocardial mitochondria (e.g. deformed cristae; ruptured membranes). Measurements of an oxidative stress marker, PrPC and an endoplasmic reticulum stress marker, GRP78, identify significant ventricular up-regulation in the highly-exposed vs lower-pollution controls. In shape/size/composition, the within-mitochondrial particles are indistinguishable from the iron-rich, combustion- and friction-derived nanoparticles prolific in roadside/urban environments, emitted from traffic/industrial sources. Incursion of myocardial mitochondria by inhaled iron-rich air pollution nanoparticles thus appears associated with mitochondrial dysfunction, and excess formation of reactive oxygen species through the iron-catalyzed Fenton reaction. Ventricular oxidative stress, as indicated by PrPC and GRP78 up-regulation, is evident even in children/young adults with minimal risk factors and no co-morbidities. These new findings indicate that myocardial iron overload resulting from inhalation of airborne, metal-rich nanoparticles is a plausible and modifiable environmental risk factor for cardiac oxidative stress and cardiovascular disease, on an international scale.

Spatial and Temporal Distribution of PM2.5 Pollution over Northeastern Mexico: Application of MERRA-2 Reanalysis Datasets

Aerosol and meteorological remote sensing data could be used to assess the distribution of urban and regional fine particulate matter (PM2.5), especially in locations where there are few or no ground-based observations, such as Latin America. The objective of this study is to evaluate the ability of Modern-Era Retrospective Analysis for Research and Application, version 2 (MERRA-2) aerosol components to represent PM2.5 ground concentrations and to develop and validate an ensemble neural network (ENN) model that uses MERRA-2 aerosol and meteorology products to estimate the monthly average of PM2.5 ground concentrations in the Monterrey Metropolitan Area (MMA), which is the main urban area in Northeastern Mexico (NEM). The project involves the application of the ENN model to a regional domain that includes not only the MMA but also other municipalities in NEM in the period from January 2010 to December 2014. Aerosol optical depth (AOD), temperature, relative humidity, dust PM2.5, sea salt PM2.5, black carbon (BC), organic carbon (OC), and sulfate (SO42−) reanalysis data were identified as factors that significantly influenced PM2.5 concentrations. The ENN estimated a PM2.5 monthly mean of 25.62 μg m−3 during the entire period. The results of the comparison between the ENN and ground measurements were as follows: correlation coefficient R ~ 0.90; root mean square error = 1.81 μg m−3; mean absolute error = 1.31 μg m−3. Overall, the PM2.5 levels were higher in winter and spring. The highest PM2.5 levels were located in the MMA, which is the major source of air pollution throughout this area. The estimated data indicated that PM2.5 was not distributed uniformly throughout the region but varied both spatially and temporally. These results led to the conclusion that the magnitude of air pollution varies among seasons and regions, and it is correlated with meteorological factors. The methodology developed in this study could be used to identify new monitoring sites and address information gaps.

Cumulative Lifetime Burden of Cardiovascular Disease From Early Exposure to Air Pollution

The disease burden associated with air pollution continues to grow. The World Health Organization (WHO) estimates ≈7 million people worldwide die yearly from exposure to polluted air, half of which-3.3 million-are attributable to cardiovascular disease (CVD), greater than from major modifiable CVD risks including smoking, hypertension, hyperlipidemia, and diabetes mellitus. This serious and growing health threat is attributed to increasing urbanization of the world's populations with consequent exposure to polluted air. Especially vulnerable are the elderly, patients with pre-existing CVD, and children. The cumulative lifetime burden in children is particularly of concern because their rapidly developing cardiopulmonary systems are more susceptible to damage and they spend more time outdoors and therefore inhale more pollutants. World Health Organization estimates that 93% of the world's children aged <15 years-1.8 billion children-breathe air that puts their health and development at risk. Here, we present growing scientific evidence, including from our own group, that chronic exposure to air pollution early in life is directly linked to development of major CVD risks, including obesity, hypertension, and metabolic disorders. In this review, we surveyed the literature for current knowledge of how pollution exposure early in life adversely impacts cardiovascular phenotypes, and lay the foundation for early intervention and other strategies that can help prevent this damage. We also discuss the need for better guidelines and additional research to validate exposure metrics and interventions that will ultimately help healthcare providers reduce the growing burden of CVD from pollution.