Diesel exhaust particulate increases the size and complexity of lesions in atherosclerotic mice

New insights into the association of air pollution and kidney diseases by tracing gold nanoparticles with inductively coupled plasma mass spectrometry

Exposure to particles from air pollution has been associated with kidney disease; however, the underlying biological mechanisms are incompletely understood. Inhaled particles can gain access to the circulation and, depending on their size, pass into urine, raising the possibility that particles may also sequester in the kidney and directly alter renal function. This study optimised an inductively coupled plasma mass spectrometry (ICP-MS) method to investigate the size dependency of particle accumulation in the kidneys of mice following pulmonary instillation (0.8 mg in total over 4 weeks) to gold nanoparticles (2, 3-4, 7-8, 14 or 40 nm or saline control). Due to the smallest particle sizes being below the limit of detection in single particle mode, ICP-MS was operated in total quantification mode. Gold was detected in all matrices of interest (blood, urine and kidney) from animals treated with all sizes of gold nanoparticles, at orders of magnitude higher than the methodological limit of detection in biological matrices (0.013 ng/mL). A size-dependent effect was observed, with smaller particles leading to greater levels of accumulation in tissues. This study highlights the value of a robust and reliable method by ICP-MS to detect extremely low levels of gold in biological samples for indirect particle tracing. The finding that nano-sized particles translocate from the lung to the kidney may provide a biological explanation for the associations between air pollution and kidney disease.

Supported Erythrocyte Membranes on Piezoelectric Sensors for Studying the Interactions with Nanoparticles

Applications of nanoparticles (NPs) in nanodrugs, food additives, and cosmetics can result in the presence of nanomaterials in the human circulatory system and their attachment to red blood cells (RBCs), which may lead to cytotoxic effects. To investigate the interactions of NPs with RBC membranes (RBCm), supported erythrocyte membranes (SRBCm) were developed on piezoelectric sensors in a quartz crystal microbalance with dissipation (QCM-D) at 25 °C. A well-dispersed RBCm suspension at 1 mM NaCl and 0.2 mM NaHCO3 was obtained from whole blood and comprised colloidal membrane fragments with the average hydrodynamic diameter and zeta potential of 390 nm and -0.53 mV, respectively, at pH 7.0. The thin and rigid SRBCm was formed mainly through the deposition of RBCm fragments on the poly-l-lysine-modified crystal sensor, leading to the average frequency shift of -26.2 Hz and the low ratio of the dissipation to frequency shift (7.2 × 10-8 Hz-1). The complete coverage of SRBCm was indicated by the plateau of the frequency shift in the stage of SRBCm formation and no deposition of negatively charged 106 nm polystyrene nanoparticles (PSNPs) on the SRBCm. Atomic force microscopy and immunofluorescence microscopy images showed that RBCm aggregates with the average size of 420 nm and erythrocyte membrane proteins existed on SRBCm, respectively. The methods of determining attachment efficiencies of model positively charged NPs (i.e., hematite NPs or HemNPs) and model negatively charged NPs (i.e., PSNPs) on SRBCm were demonstrated in 1 mM NaCl solution at pH 5.1 and pH 7.0, respectively. HemNPs exhibited a favorable deposition with an attachment efficiency of 0.99 while PSNPs did not show any attachment propensity toward SRBCm.

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.

Associations between short-term exposure to fine particulate matter and acute myocardial infarction: A case-crossover study

BACKGROUND

Previous studies evaluated the impact of particle matters (PM) on the risk of acute myocardial infarction (AMI) based on local registries.

HYPOTHESIS

This study aimed to evaluate possible short term effect of air pollutants on occurrence of AMI based on a specific case report sheet that was designed for this purpose.

METHODS

AMI was documented among 982 patients who referred to the emergency departments in Tehran, Iran, between July 2017 to March 2019. For each patient, case period was defined as 24 hour period preceding the time of emergency admission and referent periods were defined as the corresponding time in 1, 2, and 3 weeks before the admission. The associations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2 .5 ) and particulate matter with an aerodynamic diameter ≤10 μm (PM10 ) with AMI were analyzed using conditional logistic regression in a case-crossover design.

RESULT

Increase in PM2.5 and PM10 was significantly associated with the occurrence of AMI with and without adjustment for the temperature and humidity. In the adjusted model each 10 μg/m3 increase of PM10 and PM2.5 in case periods was significantly associated with increase myocardial infarction events (95% CI = 1.041-1.099, OR = 1.069 and 95% CI = 1.073-1.196, and OR = 1.133, respectively). Subgroup analysis showed that increase in PM10 did not increase AMI events in diabetic subgroup, but in all other subgroups PM10 and PM2 .5 concentration showed positive associations with increased AMI events.

CONCLUSION

Acute exposure to ambient air pollution was associated with increased risk of AMI irrespective of temperature and humidity.

Hepatoprotective Effect of Morin Hydrate in Type 2 Diabetic Wistar Rats Exposed to Diesel Exhaust Particles

Studies have shown that exposure to air pollutants such as diesel exhaust particles (DEP) exacerbate diabetes complications. Morin hydrate (MH), a plant bioflavonoid, provides hepatoprotection due to its diverse pharmacological properties. This study examines the hepatoprotective effects of MH in Wistar rats with type 2 diabetes exposed to diesel exhaust (DE). Procured male Wistar rats (n = 60) were separated into 12 groups of five rat each. Type 2 diabetes was induced following oral therapy with fructose solution and one-time injection of 45 mg/kg of streptozotocin (STZ). The DEP extract was administered by nasal instillation, whereas MH was administered via oral gavage. Biochemical assays were used to determine the effect of MH on diabetic rats and DEP-exposed diabetic rats with respect to liver function indices (AST and ALT), liver antioxidants (SOD, CAT, Gpx, and GSH), lipid profile, and oxidative stress marker (conjugated diene and lipid peroxidation). The mRNA expression of PI3K/AKT/GLUT4 and AMPK/GLUT4 signaling pathways were quantified using RT-PCR. The results show that normal rats, diabetic rats, and diabetic rats exposed to DEP exhibited a substantial decrease in oxidative stress indicators, serum lipid profile, and levels of AST and ALP, as well as an increase in liver natural antioxidants following oral administration of MH. The gene expression study demonstrated that MH promotes the activation of the insulin signaling pathways which facilitates the uptake of glucose from the blood. This study suggests that MH offered hepatoprotection in type 2 diabetic rats and DEP exposed diabetic rats.

Cold-induced adaptive thermogenesis is impaired by exposure of Asian sand dust in mice

Desertification and desert sandstorms caused by the worsening global warming pose increasing risks to human health. In particular, Asian sand dust (ASD) exposure has been related to an increase in mortality and hospital admissions for respiratory diseases. In this study, we investigated the effects of ASD on metabolic tissues in comparison to diesel particulate matter (DPM) that is known to cause adverse health effects. We found that larger lipid droplets were accumulated in the brown adipose tissues (BAT) of ASD-administered but not DPM-administered mice. Thermogenic gene expression was decreased in these mice as well. When ASD-administered mice were exposed to the cold, they failed to maintain their body temperature, suggesting that the ASD administration had led to impairments in cold-induced adaptive thermogenesis. However, impaired thermogenesis was not observed in DPM-administered mice. Furthermore, mice fed a high-fat diet that were chronically administered ASD demonstrated unexplained weight loss, indicating that chronic administration of ASD could be lethal in obese mice. We further identified that ASD-induced lung inflammation was not exacerbated in uncoupling protein 1 knockout mice, whose thermogenic capacity is impaired. Collectively, ASD exposure can impair cold-induced adaptive thermogenic responses in mice and increase the risk of mortality in obese mice.

Ambient Air Pollution and Stroke: An Updated Review

Despite recent advances in treatment and prevention, stroke remains a leading cause of morbidity and mortality. There is a critical need to identify novel modifiable risk factors for disease, including environmental agents. A body of evidence has accumulated suggesting that elevated levels of ambient air pollutants may not only trigger cerebrovascular events in susceptible people (short-term exposures) but also increase the risk of future events (long-term average exposures). This review assesses the updated evidence for both short and long-term exposure to ambient air pollution as a risk factor for stroke incidence and outcomes. It discusses the potential pathophysiologic mechanisms and makes recommendations to mitigate exposure on a personal and community level. The evidence indicates that reduction in air pollutant concentrations represent a significant population-level opportunity to reduce risk of cerebrovascular disease.

Moderate aerobic training is safe and improves glucose intolerance induced by the association of high fat diet and air pollution

Obesity and exposure to fine particulate matter (PM_2.5) are risk factors for insulin resistance, to which physical exercise is the most powerful non-pharmacological strategy. However, public concern over whether exercise could be protective in a polluted environment exists. Therefore, evaluating the possible benefits of exercise in polluted conditions in different contexts (age, gender, and cardiometabolic health) is imperative. In this sense, muscle plays a major role in maintaining glucose homeostasis, and its oxidative status is closely affected during exercise. This study tested whether moderate aerobic training could alleviate the metabolic and oxidative impairment in the gastrocnemius induced by the combination of a high-fat diet (HFD) and PM_2.5 exposure. Female mice (B6129SF2/J) received HFD (58.3% of fat) or standard diet, intranasal instillation of 20 μg residual oil fly ash (ROFA: inorganic portion of PM_2.5), or saline seven times per week for 19 weeks. In the 13th week, animals were submitted to moderate training or remained sedentary. Trained animals followed a progressive protocol for 6 weeks, ending at swimming with 5% body weight of workload for 60 min, while sedentary animals remained in shallow water. Aerobic moderate training attenuated weight gain and glucose intolerance and prevented muscle and pancreatic mass loss induced by a HFD plus ROFA exposure. Interestingly, a HFD combined with ROFA enhanced the catalase antioxidant activity, regardless of physical exercise. Therefore, our study highlights that, even in polluted conditions, moderate training is the most powerful non-pharmacological treatment for obesity and insulin resistance.

The macrophage senescence hypothesis: the role of poor heat shock response in pulmonary inflammation and endothelial dysfunction following chronic exposure to air pollution

INTRODUCTION

Cardiovascular diseases (CVD) have been associated with high exposure to fine particulate air pollutants (PM_2.5). Alveolar macrophages are the first defense against inhaled particles. As soon as they phagocytize the particles, they reach an inflammatory phenotype, which affects the surrounding cells and associates with CVD. Not coincidentally, CVD are marked by a depleted heat shock response (HSR), defined by a deficit in inducing 70-kDa heat shock protein (HSP70) expression during stressful conditions. HSP70 is a powerful anti-inflammatory chaperone, whose reduced levels trigger a pro-inflammatory milieu, cellular senescence, and a senescence-associated secretory phenotype (SASP). However, whether macrophage senescence is the main mechanism by which PM_2.5 propagates low-grade inflammation remains unclear.

OBJECTIVE AND DESIGN

In this article, we review evidence supporting that chronic exposure to PM_2.5 depletes HSR and determines the ability to solve the initial stress.

RESULTS AND DISCUSSION

When exposed to PM_2.5, macrophages increase the production of reactive oxygen species, which activate nuclear factor-kappa B (NF-κB). NF-κB is naturally a pro-inflammatory factor that drives prostaglandin E2 (PGE2) synthesis and causes fever. PGE2 can be converted into prostaglandin A2, a powerful inducer of HSR. Therefore, when transiently activated, NF-κB can trigger the anti-inflammatory response through negative feedback, by inducing HSP70 expression. However, when chronically activated, NF-κB heads a set of pathways involved in mitochondrial dysfunction, endoplasmic reticulum stress, unfolded protein response, inflammasome activation, and apoptosis. During chronic exposure to PM_2.5, cells cannot properly express sirtuin-1 or activate heat shock factor-1 (HSF-1), which delays the resolution phase of inflammation. Since alveolar macrophages are the first immune defense against PM_2.5, we suppose that the pollutant impairs HSR and, consequently, induces cellular senescence. Accordingly, senescent macrophages change its secretory phenotype to a more inflammatory one, known as SASP. Finally, macrophages' SASP would propagate the systemic inflammation, leading to endothelial dysfunction and atherosclerosis.

Diphenyl diselenide modulate antioxidant status, inflammatory and redox-sensitive genes in diesel exhaust particle-induced neurotoxicity

This study seeks to determine the influence of diphenyl diselenide (DPDSe) on redox status, inflammatory and redox-sensitive genes in diesel exhaust particle (DEP)-induced neurotoxicity in male albino rats. Male Wistar albino rats were administered nasally with DEP (30 and 60 μg/kg) and treated with intraperitoneal administration of 10 mg/kg DPDSe. Non-enzymatic (lipid peroxidation and conjugated diene concentrations) and enzymatic (catalase, superoxide dismutase, glutathione peroxidase) antioxidant indices and activity of acetylcholinesterase enzyme were evaluated in brain tissues of the rats. Furthermore, the expression of genes linked to oxidative stress (HO-1, Nrf2), pro-inflammatory (NF-KB, IL-8, TNF-α) anti-inflammatory (IL-10) and brain-specific (GFAP, ENO-2) genes were also determined. The results indicated that DPDSe caused a notable reduction in the high levels of thiobarbituric acid reactive substances and conjugated diene observed in the brain of DEP-administered rats. DPDSe also reversed the observed reduction in catalase, superoxide dismutase and glutathione peroxidase enzyme activities in the brain of DEP-administered rats. Lastly, the downregulation of genes associated with redox homeostasis, anti-inflammatory and brain-specific genes and upregulation of pro-inflammatory genes observed in the DEP-treated groups were ameliorated by DPDSe. The immediate restoration of altered biochemical conditions and molecular expression in the brain of DEP-treated rats by DPDSe further validates its use as a promising therapeutic candidate for restoring neurotoxicity linked with DEP-induced oxidative stress.

Neurotoxicity of Engineered Nanomaterials: Testing Considerations

As with toxicology in general, major challenges have emerged in its subfield neurotoxicology regarding the testing of engineered nanomaterials (ENM). This is on the one hand due to their complex physicochemical properties, like size, specific surface area, chemical composition as well as agglomeration and dissolution behavior in biological environments. On the other hand, toxicological risk assessment has faced an increasing demand for the development and implementation of non-animal alternative approaches. Regarding the investigation and interpretation of the potential adverse effects of ENM on the brain, toxicokinetic data are relatively scarce and thus hampers dose selection for in vitro neurotoxicity testing. Moreover, recent in vivo studies indicate that ENM can induce neurotoxic and behavioral effects in an indirect manner, depending on their physicochemical properties and route of exposure. Such indirect effects on the brain may proceed through the activation and spill-over of inflammatory mediators by ENM in the respiratory tract and other peripheral organs as well via ENM induced disturbance of the gut microbiome and intestinal mucus barrier. These ENM specific aspects should be incorporated into the ongoing developments of advanced in vitro neurotoxicity testing methods and strategies.

Protective actions of nuclear factor erythroid 2-related factor 2 (NRF2) and downstream pathways against environmental stressors

Environmental risk factors, including noise, air pollution, chemical agents, ultraviolet radiation (UVR) and mental stress have a considerable impact on human health. Oxidative stress and inflammation are key players in molecular pathomechanisms of environmental pollution and risk factors. In this review, we delineate the impact of environmental risk factors and the protective actions of the nuclear factor erythroid 2-related factor 2 (NRF2) in connection to oxidative stress and inflammation. We focus on well-established studies that demonstrate the protective actions of NRF2 and its downstream pathways against different environmental stressors. State-of-the-art mechanistic considerations on NRF2 signaling are discussed in detail, e.g. classical concepts like KEAP1 oxidation/electrophilic modification, NRF2 ubiquitination and degradation. Specific focus is also laid on NRF2-dependent heme oxygenase-1 induction with detailed presentation of the protective down-stream pathways of heme oxygenase-1, including interaction with BACH1 system. The significant impact of all environmental stressors on the circadian rhythm and the interactions of NRF2 with the circadian clock will also be considered here. A broad range of NRF2 activators is discussed in relation to environmental stressor-induced health side effects, thereby suggesting promising new mitigation strategies (e.g. by nutraceuticals) to fight the negative effects of the environment on our health.

Establishment of Repeated In Vitro Exposure System for Evaluating Pulmonary Toxicity of Representative Criteria Air Pollutants Using Advanced Bronchial Mucosa Models

There is mounting evidence that shows the association between chronic exposure to air pollutants (particulate matter and gaseous) and onset of various respiratory impairments. However, the corresponding toxicological mechanisms of mixed exposure are poorly understood. Therefore, in this study, we aimed to establish a repeated exposure setting for evaluating the pulmonary toxicological effects of diesel exhaust particles (DEP), nitrogen dioxide (NO2), and sulfur dioxide (SO2) as representative criterial air pollutants. Single, combined (DEP with NO2 and SO2), and repeated exposures were performed using physiologically relevant human bronchial mucosa models developed at the air−liquid interface (bro-ALI). The bro-ALI models were generated using human primary bronchial epithelial cells (3−4 donors; 2 replicates per donor). The exposure regime included the following: 1. DEP (12.5 µg/cm2; 3 min/day, 3 days); 2. low gaseous (NO2: 0.1 ppm + SO2: 0.2 ppm); (30 min/day, 3 days); 3. high gaseous (NO2: 0.2 ppm + SO2: 0.4 ppm) (30 min/day, 3 days); and 4. single combined (DEP + low gaseous for 1 day). The markers for pro-inflammatory (IL8, IL6, NFKB, TNF), oxidative stress (HMOX1, GSTA1, SOD3,) and tissue injury/repair (MMP9, TIMP1) responses were assessed at transcriptional and/ or secreted protein levels following exposure. The corresponding sham-exposed samples under identical conditions served as the control. A non-parametric statistical analysis was performed and p < 0.05 was considered as significant. Repeated exposure to DEP and single combined (DEP + low gaseous) exposure showed significant alteration in the pro-inflammatory, oxidative stress and tissue injury responses compared to repeated exposures to gaseous air pollutants. The study demonstrates that it is feasible to predict the long-term effects of air pollutants using the above explained exposure system.

Probiotics Function as Immunomodulators in the Intestine in C57Bl/6 Male Mice Exposed to Inhaled Diesel Exhaust Particles on a High-Fat Diet

Epidemiological studies reveal a correlation between air pollution exposure and gastrointestinal (GI) diseases, yet few studies have investigated the role of inhaled particulate matter on intestinal integrity in conjunction with a high-fat (HF) diet. Additionally, there is currently limited information on probiotics in mitigating air-pollutant responses in the intestines. Thus, we investigated the hypothesis that exposure to inhaled diesel exhaust particles (DEP) and a HF diet can alter intestinal integrity and inflammation, which can be attenuated with probiotics. 4-6-w-old male C57Bl/6 mice on a HF diet (45% kcal fat) were randomly assigned to be exposed via oropharyngeal aspiration to 35 µg of DEP suspended in 35 µL of 0.9% sterile saline or sterile saline (CON) only twice a week for 4 w. A subset of mice was treated with 0.3 g/day of Winclove Ecologic^® barrier probiotics (PRO) in drinking water throughout the duration of the study. Our results show that DEP exposure ± probiotics resulted in increased goblet cells and mucin (MUC)-2 expression, as determined by AB/PAS staining. Immunofluorescent quantification and/or RT-qPCR showed that DEP exposure increases claudin-3, occludin, zona occludens (ZO)-1, matrix metalloproteinase (MMP)-9, and toll-like receptor (TLR)-4, and decreases tumor necrosis factor (TNF)-α and interleukin (IL)-10 expression compared to CON. DEP exposure + probiotics increases expression of claudin-3, occludin, ZO-1, TNF-α, and IL-10 and decreases MMP-9 and TLR-4 compared to CON + PRO in the small intestine. Collectively, these results show that DEP exposure alters intestinal integrity and inflammation in conjunction with a HF diet. Probiotics proved fundamental in understanding the role of the microbiome in protecting and altering inflammatory responses in the intestines following exposure to inhaled DEP.

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.

Gestational exposure to titanium dioxide, diesel exhaust, and concentrated urban air particles affects levels of specialized pro-resolving mediators in response to allergen in asthma-susceptible neonate lungs

Maternal gestational exposures to traffic and urban air pollutant particulates have been linked to increased risk and/or worsening asthma in children; however, mechanisms underlying this vertical transmission are not entirely understood. It was postulated that gestational particle exposure might affect the ability to elicit specialized proresolving mediator (SPM) responses upon allergen encounter in neonates. Lipidomic profiling of 50 SPMs was performed in lungs of neonates born to mice exposed to concentrated urban air particles (CAP), diesel exhaust particles (DEP), or less immunotoxic titanium dioxide particles (TiO2). While asthma-like phenotypes were induced with identical eosinophilia intensity across neonates of all particle-exposed mothers, levels of LXA4, HEPE and HETE isoforms, and HDoHe were only decreased by CAP and DEP only but not by TiO2. However, RvE2 and RvD1 were inhibited by all particles. In contrast, isomers of Maresin1 and Protectin D1 were variably elevated by CAP and DEP, whereas Protectin DX, PGE2, and TxB2 were increased in all groups. Only Protectin D1/DX, MaR1(n-3,DPA), 5(S),15(S)-DiHETE, PGE2, and RvE3 correlated with eosinophilia but the majority of other analytes, elevated or inhibited, showed no marked correlation with inflammation intensity. Evidence indicates that gestational particle exposure leads to both particle-specific and nonspecific effects on the SPM network.

Inhaled diesel exhaust particles result in microbiome-related systemic inflammation and altered cardiovascular disease biomarkers in C57Bl/6 male mice

Background

The gut microbiota plays a vital role in host homeostasis and is associated with inflammation and cardiovascular disease (CVD) risk. Exposure to particulate matter (PM) is a known mediator of inflammation and CVD and is reported to promote dysbiosis and decreased intestinal integrity. However, the role of inhaled traffic-generated PM on the gut microbiome and its corresponding systemic effects are not well-characterized. Thus, we investigated the hypothesis that exposure to inhaled diesel exhaust particles (DEP) alters the gut microbiome and promotes microbial-related inflammation and CVD biomarkers. 4–6-week-old male C57Bl/6 mice on either a low-fat (LF, 10% fat) or high-fat (HF, 45% fat) diet were exposed via oropharyngeal aspiration to 35 μg DEP suspended in 35 μl saline or saline only (CON) 2x/week for 30 days. To determine whether probiotics could prevent diet or DEP exposure mediated alterations in the gut microbiome or systemic outcomes, a subset of animals on the HF diet were treated orally with 0.3 g/day (~ 7.5 × 10⁸ CFU/day) of Winclove Ecologic® Barrier probiotics throughout the study.

Results

Our results show that inhaled DEP exposure alters gut microbial profiles, including reducing Actinobacteria and expanding Verrucomicrobia and Proteobacteria. We observed increased circulating LPS, altered circulating cytokines (IL-1α, IL-3, IL-13, IL-15, G-CSF, LIF, MIP-2, and TNF-α), and CVD biomarkers (siCAM, PAI-1, sP-Selectin, thrombomodulin, and PECAM) in DEP-exposed and/or HF diet mice. Furthermore, probiotics attenuated the observed reduction of Actinobacteria and expansion of Proteobacteria in DEP-exposed and HF-diet mice. Probiotics mitigated circulating cytokines (IL-3, IL-13, G-CSF, RANTES, and TNF- α) and CVD biomarkers (siCAM, PAI-1, sP-Selectin, thrombomodulin, and PECAM) in respect to DEP-exposure and/or HF diet.

Conclusion

Key findings of this study are that inhaled DEP exposure alters small intestinal microbial profiles that play a role in systemic inflammation and early CVD biomarkers. Probiotic treatment in this study was fundamental in understanding the role of inhaled DEP on the microbiome and related systemic inflammatory and CVD biomarkers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-022-00452-3.

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.

The cardiovascular effects of air pollution: Prevention and reversal by pharmacological agents

Air pollution is associated with staggering levels of cardiovascular morbidity and mortality. Airborne particulate matter (PM), in particular, has been associated with a wide range of detrimental cardiovascular effects, including impaired vascular function, raised blood pressure, alterations in cardiac rhythm, blood clotting disorders, coronary artery disease, and stroke. Considerable headway has been made in elucidating the biological processes underlying these associations, revealing a labyrinth of multiple interacting mechanistic pathways. Several studies have used pharmacological agents to prevent or reverse the cardiovascular effects of PM; an approach that not only has the advantages of elucidating mechanisms, but also potentially revealing therapeutic agents that could benefit individuals that are especially susceptible to the effects of air pollution. This review gathers investigations with pharmacological agents, offering insight into the biology of how PM, and other air pollutants, may cause cardiovascular morbidity.

Accelerated atherosclerosis caused by serum amyloid A response in lungs of ApoE-/- mice

Airway exposure to eg particulate matter is associated with cardiovascular disease including atherosclerosis. Acute phase genes, especially Serum Amyloid A3 (Saa3), are highly expressed in the lung following pulmonary exposure to particles. We aimed to investigate whether the human acute phase protein SAA (a homolog to mouse SAA3) accelerated atherosclerotic plaque progression in Apolipoprotein E knockout (ApoE^-/- ) mice. Mice were intratracheally (i.t.) instilled with vehicle (phosphate buffered saline) or 2 µg human SAA once a week for 10 weeks. Plaque progression was assessed in the aorta using noninvasive ultrasound imaging of the aorta arch as well as by en face analysis. Additionally, lipid peroxidation, SAA3, and cholesterol were measured in plasma, inflammation was determined in lung, and mRNA levels of the acute phase genes Saa1 and Saa3 were measured in the liver and lung, respectively. Repeated i.t. instillation with SAA caused a significant progression in the atherosclerotic plaques in the aorta (1.5-fold). Concomitantly, SAA caused a statistically significant increase in neutrophils in bronchoalveolar lavage fluid (625-fold), in pulmonary Saa3 (196-fold), in systemic SAA3 (1.8-fold) and malondialdehyde levels (1.14-fold), indicating acute phase response (APR), inflammation and oxidative stress. Finally, pulmonary exposure to SAA significantly decreased the plasma levels of very low-density lipoproteins - low-density lipoproteins and total cholesterol, possibly due to lipids being sequestered in macrophages or foam cells in the arterial wall. Combined these results indicate the importance of the pulmonary APR and SAA3 for plaque progression.

Vehicle emissions-exposure alters expression of systemic and tissue-specific components of the renin-angiotensin system and promotes outcomes associated with cardiovascular disease and obesity in wild-type C57BL/6 male mice

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Vehicle emission-exposure increases systemic and adipose renin-angiotensin signaling.

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Emission-exposure promotes renal, vascular, and adipocyte AT1 receptor expression.

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Diet and emission-exposure are associated with adipocyte hypertrophy and weight gain.

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Emission-exposure promotes expression of adipokines and adipose inflammatory factors.

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High-fat diet promotes an obese adipose phenotype, exacerbated by emission-exposure.

Exposure to air pollution from traffic-generated sources is known to contribute to the etiology of inflammatory diseases, including cardiovascular disease (CVD) and obesity; however, the signaling pathways involved are still under investigation. Dysregulation of the renin-angiotensin system (RAS) can contribute to CVD and alter lipid storage and inflammation in adipose tissue. Our previous exposure studies revealed that traffic-generated emissions increase RAS signaling, further exacerbated by a high-fat diet. Thus, we investigated the hypothesis that exposure to engine emissions increases systemic and local adipocyte RAS signaling, promoting the expression of factors involved in CVD and obesity. Male C57BL/6 mice (6–8 wk old) were fed either a high-fat (HF, n = 16) or low-fat (LF, n = 16) diet, beginning 30d prior to exposures, and then exposed via inhalation to either filtered air (FA, controls) or a mixture of diesel engine + gasoline engine vehicle emissions (MVE: 100 μg PM/m³) via whole-body inhalation for 6 h/d, 7 d/wk, 30d. Endpoints were assessed via immunofluorescence and RT-qPCR. MVE-exposure promoted vascular adhesion factors (VCAM-1, ICAM-1) expression, monocyte/macrophage sequestration, and oxidative stress in the vasculature, associated with increased angiotensin II receptor type 1 (AT1) expression. In the kidney, MVE-exposure promoted the expression of renin, AT1, and AT2 receptors. In adipose tissue, both HF-diet and MVE-exposure mediated increased epididymal fat pad weight and adipocyte hypertrophy, associated with increased angiotensinogen and AT1 receptor expression; however, these outcomes were further exacerbated in the MVE + HF group. MVE-exposure also induced inflammation, monocyte chemoattractant protein (MCP)-1, and leptin, while reducing insulin receptor and glucose transporter, GLUT4, expression in adipose tissue. Our results indicate that MVE-exposure promotes systemic and local adipose RAS signaling, associated with increased expression of factors contributing to CVD and obesity, further exacerbated by HF diet consumption.

Methyl tertiary-butyl ether inhibits THP-1 macrophage cholesterol efflux in vitro and accelerates atherosclerosis in ApoE-deficient mice in vivo

The biosafety of methyl tertiary-butyl ether (MTBE), mainly used as a gasoline additive, has long been a contentious topic. In addition to its routine toxicities, MTBE has been demonstrated to disrupt glucose and lipid metabolism and contribute to the development of type 2 diabetes as well as obesity. As one of the morbidities related to dyslipidemia, atherosclerosis is worthy of being investigated under MTBE exposure. Since foam cells derived from macrophages play pivotal roles during atherosclerosis development, we studied the effects of MTBE on macrophages in vitro and assessed the effect of MTBE on atherosclerosis plaque formation with the ApoE^-/- mouse model in vivo for the first time. Our results demonstrated that exposure to MTBE at environmentally relevant concentrations decreased the expression of ABCA1 and ABCG1, which are responsible for macrophage cholesterol efflux, at both mRNA and protein levels in THP-1 macrophages. Consequently, treatment with MTBE inhibited the transport of cholesterol from macrophages to High-density lipoprotein. ApoE^-/- mice exposed to MTBE at environmentally relevant concentrations (100, 1000 μg/kg) displayed significant increases in lesion area in the aorta and aortic root compared to vehicle-treated ones. Further analysis indicated that MTBE exposure enhanced the macrophage-specific marker Mac-2 contents within plaques in the aortic root, implying that MTBE could promote macrophage-derived foam cell formation and thus accelerate atherosclerosis plaque formation. We for the first time demonstrated the pro-atherogenic effect of MTBE via eliciting disruption of macrophage cholesterol efflux and accelerating foam cell formation and atherosclerosis plaque development.

Accelerated Aging and Age-Related Diseases (CVD and Neurological) Due to Air Pollution and Traffic Noise Exposure

The World Health Organization estimates that only approximately 25% of diversity in longevity is explained by genetic factors, while the other 75% is largely determined by interactions with the physical and social environments. Indeed, aging is a multifactorial process that is influenced by a range of environmental, sociodemographic, and biopsychosocial factors, all of which might act in concert to determine the process of aging. The global average life expectancy increased fundamentally over the past century, toward an aging population, correlating with the development and onset of age-related diseases, mainly from cardiovascular and neurological nature. Therefore, the identification of determinants of healthy and unhealthy aging is a major goal to lower the burden and socioeconomic costs of age-related diseases. The role of environmental factors (such as air pollution and noise exposure) as crucial determinants of the aging process are being increasingly recognized. Here, we critically review recent findings concerning the pathomechanisms underlying the aging process and their correlates in cardiovascular and neurological disease, centered on oxidative stress and inflammation, as well as the influence of prominent environmental pollutants, namely air pollution and traffic noise exposure, which is suggested to accelerate the aging process. Insight into these types of relationships and appropriate preventive strategies are urgently needed to promote healthy aging.

Diesel exhaust particles alter the profile and function of the gut microbiota upon subchronic oral administration in mice

BACKGROUND

Ambient air pollution by particulate matters, including diesel exhaust particles (DEP), is a major cause of cardiovascular and metabolic mortality worldwide. The mechanisms by which DEP cause these adverse outcomes are not completely understood. Because the gut microbiota controls cardiovascular and metabolic health, we hypothesized that the fraction of inhaled DEP which reach the gut after mucociliary clearance and swallowing might induce gut dysbiosis and, in turn, contribute to aggravate or induce cardiovascular and metabolic diseases.

RESULTS

Female ApoE^-/- mice fed a Western diet, and wild-type (C57Bl/6) mice fed standard diet were gavaged with DEP (SRM2975) doses corresponding to mucociliary clearance from inhalation exposure (200 or 1000 ng/day, 3 times a week for 3 months; and 40, 200 or 1000 ng/day, 3 times a week for 6 months, respectively). No mortality, overt systemic or digestive toxicity was observed. A dose-dependent alteration of the gut microbiota was recorded in both strains. In ApoE^-/-, β-diversity was modified by DEP, but no significant modification of the relative abundance of the phyla, families or genera was identified. In C57BL/6 mice, DEP reduced α-diversity (Shannon and Simpson indices), and modified β-diversity, including a reduction of the Proteobacteria and Patescibacteria phyla, and an increase of the Campylobacterota phylum. In both mouse models, perturbation of the gut microbiota composition was associated with a dose-dependent reduction of bacterial short chain fatty acids (butyrate and propionate) in cecal content. However, DEP ingestion did not aggravate (ApoE^-/-), or induce (C57BL/6 mice) atherosclerotic plaques, and no metabolic alteration (glucose tolerance, resistance to insulin, or lipidemia) was recorded.

CONCLUSIONS

We show here that oral exposure to DEP, at doses relevant for human health, changes the composition and function of the gut microbiota. These modifications were, however, not translated into ultimate atherosclerotic or metabolic outcomes.

Two Web-Based and Theory-Based Interventions With and Without Brief Motivational Interviewing in the Promotion of Human Papillomavirus Vaccination Among Chinese Men Who Have Sex With Men: Randomized Controlled Trial

Background

Human papillomavirus (HPV) vaccination is effective in the prevention of vaccine-type genital warts and cancers among men who have sex with men (MSM).

Objective

The primary objective of this randomized controlled trial (RCT) is to evaluate the efficacies of 2 web- and theory–based interventions with and without brief motivational interviewing (MI) over the phone to increase the completion of HPV vaccination among unvaccinated participants within a 24-month follow-up period compared with the control group.

Methods

A 3-arm parallel-group RCT was conducted between July 2017 and December 2019. Five telephone surveys were conducted at baseline and at 3, 6, 9, and 24 months by blinded interviewers. Participants were Hong Kong Chinese–speaking MSM aged between 18 and 45 years with regular internet access who were recruited from outreaching at venues, web-based recruitment, and peer referral. Those who had ever received HPV vaccination were excluded. A total of 624 participants were randomized into either the online tutorial (OT) only group (n=208), the OT plus MI group (OT-MI; n=208), or the control group (n=208). In total, 459 (459/624, 73.6%) completed the follow-up evaluation at 24 months. Participants in the OT group received a fully automated OT developed based on the health belief model. On top of the same OT, the OT-MI group received brief MI over the phone. Reminders were sent to the participants of the OT and OT-MI groups after 1, 2, 4, 6, and 8 months. Participants in the control group received web-based health communication messages unrelated to HPV or HPV vaccination. The research team validated the self-reported HPV vaccination uptake. Intention-to-treat analysis was used for outcome analyses. Logistic regression models and multivariable linear regression models were used to test the between-group differences in primary and secondary outcomes. Baron and Kenny’s methods were used to test the mediation hypothesis.

Results

The participants in the OT-MI group reported a significantly higher validated completion of HPV vaccination at 24 months than the control group (36/208, 17.3% vs 15/208, 7.2%; P=.006). However, the difference in HPV vaccination completion between the OT and the control groups (24/208, 11.5% vs 15/208, 7.2%; P=.17), or between OT-MI and OT groups (P=.13), was not statistically significant. The association between randomization status (OT-MI group vs control group) and HPV vaccination completion became statistically nonsignificant after controlling for changes in the perceived susceptibility to HPV (24 months vs baseline), whereas perceived susceptibility remained strongly associated with HPV vaccination uptake in the model (P<.001). Changes in perceived susceptibility fully mediated the intervention effect.

Conclusions

Theory-based OT with brief MI over the phone was effective in increasing HPV vaccination completion among Chinese MSM. Perceived susceptibility is an active theoretical component that causes behavioral changes.

Trial Registration

ClinicalTrials.gov NCT03286907; https://clinicaltrials.gov/ct2/show/NCT03286907

Particulate matter inhalation and the exacerbation of cardiopulmonary toxicity due to metabolic disease

Particulate matter is a significant public health issue in the United States and globally. Inhalation of particulate matter is associated with a number of systemic and organ-specific adverse health outcomes, with the pulmonary and cardiovascular systems being particularly vulnerable. Certain subpopulations are well-recognized as being more susceptible to inhalation exposures, such as the elderly and those with pre-existing respiratory disease. Metabolic syndrome is becoming increasingly prevalent in our society and has known adverse effects on the heart, lungs, and vascular systems. The limited evaluations of individuals with metabolic syndromehave demonstrated that theymay compose a sensitive subpopulation to particulate exposures. However, the toxicological mechanisms responsible for this increased vulnerability are not fully understood. This review evaluates the currently available literature regarding how the response of an individual's pulmonary and cardiovascular systems is influenced by metabolic syndrome and metabolic syndrome-associated conditions such as hypertension, dyslipidemia, and diabetes. Further, we will discuss potential therapeutic agents and targets for the alleviation and treatment of particulate-matter induced metabolic illness. The information reviewed here may contribute to the understanding of metabolic illness as a risk factor for particulate matter exposure and further the development of therapeutic approaches to treat vulnerable subpopulations, such as those with metabolic diseases.

Exposure to diesel exhaust particles results in altered lung microbial profiles, associated with increased reactive oxygen species/reactive nitrogen species and inflammation, in C57Bl/6 wildtype mice on a high-fat diet

BACKGROUND

Exposure to traffic-generated emissions is associated with the development and exacerbation of inflammatory lung disorders such as chronic obstructive pulmonary disorder (COPD) and idiopathic pulmonary fibrosis (IPF). Although many lung diseases show an expansion of Proteobacteria, the role of traffic-generated particulate matter pollutants on the lung microbiota has not been well-characterized. Thus, we investigated the hypothesis that exposure to diesel exhaust particles (DEP) can alter commensal lung microbiota, thereby promoting alterations in the lung's immune and inflammatory responses. We aimed to understand whether diet might also contribute to the alteration of the commensal lung microbiome, either alone or related to exposure. To do this, we used male C57Bl/6 mice (4-6-week-old) on either regular chow (LF) or high-fat (HF) diet (45% kcal fat), randomly assigned to be exposed via oropharyngeal aspiration to 35 μg DEP, suspended in 35 μl 0.9% sterile saline or sterile saline only (control) twice a week for 30 days. A separate group of study animals on the HF diet was concurrently treated with 0.3 g/day of Winclove Ecologic® Barrier probiotics in their drinking water throughout the study.

RESULTS

Our results show that DEP-exposure increases lung tumor necrosis factor (TNF)-α, interleukin (IL)-10, Toll-like receptor (TLR)-2, TLR-4, and the nuclear factor kappa B (NF-κB) histologically and by RT-qPCR, as well as Immunoglobulin A (IgA) and Immunoglobulin G (IgG) in the bronchoalveolar lavage fluid (BALF), as quantified by ELISA. We also observed an increase in macrophage infiltration and peroxynitrite, a marker of reactive oxygen species (ROS) + reactive nitrogen species (RNS), immunofluorescence staining in the lungs of DEP-exposed and HF-diet animals, which was further exacerbated by concurrent DEP-exposure and HF-diet consumption. Histological examinations revealed enhanced inflammation and collagen deposition in the lungs DEP-exposed mice, regardless of diet. We observed an expansion of Proteobacteria, by qPCR of bacterial 16S rRNA, in the BALF of DEP-exposed mice on the HF diet, which was diminished with probiotic-treatment.

CONCLUSIONS

Our findings suggest that exposure to DEP causes persistent and sustained inflammation and bacterial alterations in a ROS-RNS mediated fashion, which is exacerbated by concurrent consumption of an HF diet.

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.

Acute exposure to traffic-related air pollution alters antioxidant status in healthy adults

BACKGROUND

Exposure to traffic-related air pollution is associated with an increased risk of cardiovascular and respiratory disease. Evidence suggests that inhaled pollutants precipitate these effects via multiple pathways involving oxidative stress.

OBJECTIVE

Postulating that a decrease in circulating antioxidant levels reflect an oxidative response, we investigated the effect of inhaled diesel exhaust (DE) on the ratio of reduced to oxidized glutathione (GSH/GSSG) in healthy adults, and whether pre-exposure antioxidant supplementation blunted this response. We also examined exposure-related changes in antioxidant/stress response leukocyte gene expression (GCLc, HMOX-1, IL-6, TGFβ) and plasma IL-6 levels.

METHODS

Nineteen nonsmoking adults participated in a double-blind, randomized, four-way crossover study. Each subject completed 120-min exposures to filtered air and DE (200 μg/m3), with and without antioxidant pretreatment. Antioxidant comprised 1000 mg ascorbate for 7 days and 1200 mg N-acetylcysteine 1 day prior to exposure, with 1000 mg and 600 mg, respectively, administered 2 h prior to exposure. Whole blood glutathione was measured pre- and post-exposure; plasma IL-6 and mRNA expression were quantified pre, during and post exposure.

RESULTS

Diesel exhaust exposure was associated with significantly decreased GSH/GSSG (p = 0.001) and a 4-fold increase in IL-6 mRNA (p = 0.01) post exposure. Antioxidant pretreatment did not significantly mediate the effect of DE exposure on GSH/GSSG, though appeared to decrease the effect of exposure on IL-6 mRNA expression.

CONCLUSIONS

Acute DE inhalation induced detectable oxidative effects in healthy adults, which were not significantly attenuated by the selected antioxidant pre-treatment. This finding supports the premise that oxidative stress is one mechanism underlying the adverse effects of traffic-related air pollution.

Effects of ambient particulate matter on vascular tissue: a review

Fine and ultra-fine particulate matter (PM) are major constituents of urban air pollution and recognized risk factors for cardiovascular diseases. This review examined the effects of PM exposure on vascular tissue. Specific mechanisms by which PM affects the vasculature include inflammation, oxidative stress, actions on vascular tone and vasomotor responses, as well as atherosclerotic plaque formation. Further, there appears to be a greater PM exposure effect on susceptible individuals with pre-existing cardiovascular conditions.

Air pollution and cardiovascular disease: car sick

The cardiovascular effects of inhaled particle matter (PM) are responsible for a substantial morbidity and mortality attributed to air pollution. Ultrafine particles, like those in diesel exhaust emissions, are a major source of nanoparticles in urban environments, and it is these particles that have the capacity to induce the most significant health effects. Research has shown that diesel exhaust exposure can have many detrimental effects on the cardiovascular system both acutely and chronically. This review provides an overview of the cardiovascular effects on PM in air pollution, with an emphasis on ultrafine particles in vehicle exhaust. We consider the biological mechanisms underlying these cardiovascular effects of PM and postulate that cardiovascular dysfunction may be implicated in the effects of PM in other organ systems. The employment of multiple strategies to tackle air pollution, and especially ultrafine particles from vehicles, is likely to be accompanied by improvements in cardiovascular health.

The association of subchronic exposure to low concentration of PM2.5 and high-fat diet potentiates glucose intolerance development, by impairing adipose tissue antioxidant defense and eHSP72 levels

The subchronic exposure to fine particulate matter (PM2.5) and high-fat diet (HFD) consumption lead to glucose intolerance by different mechanisms involving oxidative stress and inflammation. Under stressful conditions, the cells exert a heat shock response (HSR), by releasing the 72-kDa heat shock proteins (eHSP72), fundamental chaperones. The depletion of the HSR can exacerbate the chronic inflammation. However, there are few studies about the early effects of the association of HFD consumption and exposure to low concentrations of PM2.5 in the oxidative stress and HSR, in the genesis of glucose intolerance. Thus, we divided 23 male B6129SF2/J mice into control (n = 6), polluted (n = 6), HFD (n = 6), and high-fat diet + polluted (HFD + polluted) (n = 5) groups. Control and polluted received a standard diet (11.4% of fats), while HFD and HFD + polluted received HFD (58.3% of fats). Simultaneously, polluted and HFD + polluted received 5 μg/10 μL of PM2.5, daily, 7×/week, while control and HFD were exposed to 10 μL of saline solution 0.9% for 12 weeks. At the 12th week, animals were euthanized. We collected the metabolic tissues to analyze oxidative parameters, total blood to the hematological parameters, and plasma to eHSP72 measurement. The association of HFD and PM2.5 impaired glucose tolerance in the 12th week. Besides, it triggered an antioxidant defense by the adipose tissue, which was negatively correlated with eHSP72 levels. In conclusion, a low concentration of PM2.5 exposure associated with HFD consumption leads to glucose intolerance, by impairing adipose tissue antioxidant defense and systemic eHSP72 levels.

Evaluation of neurological effects of cerium dioxide nanoparticles doped with different amounts of zirconium following inhalation exposure in mouse models of Alzheimer's and vascular disease

Increasing evidence from toxicological and epidemiological studies indicates that the brain is an important target for ambient (ultrafine) particles. Disturbance of redox-homeostasis and inflammation in the brain are proposed as possible mechanisms that can contribute to neurotoxic and neurodegenerative effects. Whether and how engineered nanoparticles (NPs) may cause neurotoxicity and promote neurodegenerative diseases such as Alzheimer's disease (AD) is largely unstudied. We have assessed the neurological effects of subacute inhalation exposures (4 mg/m³ for 3 h/day, 5 days/week for 4 weeks) to cerium dioxide (CeO₂) NPs doped with different amounts of zirconium (Zr, 0%, 27% and 78%), to address the influence of particle redox-activity in the 5xFAD transgenic mouse model of AD. Four weeks post-exposure, effects on behaviour were evaluated and brain tissues were analysed for amyloid-β plaque formation and reactive microglia (Iba-1 staining). Behaviour was also evaluated in concurrently exposed non-transgenic C57BL/6J littermates, as well as in Western diet-fed apolipoprotein E-deficient (ApoE^-/-) mice as a model of vascular disease. Markers of inflammation and oxidative stress were evaluated in brain cortex. The brains of the NP-exposed 5xFAD mice revealed no accelerated amyloid-β plaque formation. No significant treatment-related behaviour impairments were observed in the healthy C57BL/6J mice. In the 5xFAD and ApoE^-/- models, the NP inhalation exposures did not affect the alternation score in the X-maze indicating absence of spatial working memory deficits. However, following inhalation exposure to the 78% Zr-doped CeO₂ NPs changes in forced motor performance (string suspension) and exploratory motor activity (X-maze) were observed in ApoE^-/- and 5xFAD mice, respectively. Exposure to the 78% doped NPs also caused increased cortical expression of glial fibrillary acidic protein (GFAP) in the C57BL/6J mice. No significant treatment-related changes neuroinflammation and oxidative stress were observed in the 5xFAD and ApoE^-/- mice. Our study findings reveal that subacute inhalation exposure to CeO₂ NPs does not accelerate the AD-like phenotype of the 5xFAD model. Further investigation is warranted to unravel whether the redox-activity dependent effects on motor activity as observed in the mouse models of AD and vascular disease result from specific neurotoxic effects of these NPs.

Pathogenic Role of Air Pollution Particulate Matter in Cardiometabolic Disease: Evidence from Mice and Humans

Significance: Air pollution is a considerable global threat to human health that dramatically increases the risk for cardiovascular pathologies, such as atherosclerosis, myocardial infarction, and stroke. An estimated 4.2 million cases of premature deaths worldwide are attributable to outdoor air pollution. Among multiple other components, airborne particulate matter (PM) has been identified as the major bioactive constituent in polluted air. While PM-related illness was historically thought to be confined to diseases of the respiratory system, overwhelming clinical and experimental data have now established that acute and chronic exposure to PM causes a systemic inflammatory and oxidative stress response that promotes cardiovascular disease. Recent Advances: A large body of evidence has identified an impairment of redox metabolism and the generation of oxidatively modified lipids and proteins in the lung as initial tissue response to PM. In addition, the pathogenicity of PM is mediated by an inflammatory response that involves PM uptake by tissue-resident immune cells, the activation of proinflammatory pathways in various cell types and organs, and the release of proinflammatory cytokines as locally produced tissue response signals that have the ability to affect organ function in a remote manner. Critical Issues: In the present review, we summarize and discuss the functional participation of PM in cardiovascular pathologies and its risk factors with an emphasis on how oxidative stress, inflammation, and immunity interact and synergize as a response to PM. Future Directions: The impact of PM constituents, doses, and novel anti-inflammatory therapies against PM-related illness is also discussed.

Vehicular Particulate Matter (PM) Characteristics Impact Vascular Outcomes Following Inhalation

Roadside proximity and exposure to mixed vehicular emissions (MVE) have been linked to adverse pulmonary and vascular outcomes. However, because of the complex nature of the contribution of particulate matter (PM) versus gases, it is difficult to decipher the precise causative factors regarding PM and the copollutant gaseous fraction. To this end, C57BL/6 and apolipoprotein E knockout mice (ApoE-/-) were exposed to either filtered air (FA), fine particulate (FP), FP+gases (FP+G), ultrafine particulate (UFP), or UFP+gases (UFP+G). Two different timeframes were employed: 1-day (acute) or 30-day (subchronic) exposures. Examined biological endpoints included aortic vasoreactivity, aortic lesion quantification, and aortic mRNA expression. Impairments in vasorelaxation were observed following acute exposure to FP+G in C57BL/6 animals and FP, UFP, and UFP+G in ApoE-/- animals. These effects were completely abrogated or markedly reduced following subchronic exposure. Aortic lesion quantification in ApoE-/- animals indicated a significant increase in atheroma size in the UFP-, FP-, and FP+G-exposed groups. Additionally, ApoE-/- mice demonstrated a significant fold increase in TNFα expression following FP+G exposure and ET-1 following UFP exposure. Interestingly, C57BL/6 aortic gene expression varied widely across exposure groups. TNFα decreased significantly following FP exposure and CCL-5 decreased in the UFP-, FP-, and FP+G-exposed groups. Conversely, ET-1, CCL-2, and CXCL-1 were all significantly upregulated in the FP+G group. These findings suggest that gas-particle interactions may play a role in vascular toxicity, but the contribution of surface area is not clear.

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.

Cardiovascular effects of airborne particulate matter: A review of rodent model studies

In recent year, animal models have been growingly used to increase our knowledge about the toxicity of PM and underlying mechanisms leading to cardiovascular diseases. In this article, we review the current state of knowledge and findings of studies investigating the cardiovascular effects of PM in rats and mice. The six main areas covered in this review include: I) nature of particulate matter and toxicity mechanisms, II) systemic inflammation, III) heart rate and heart rate variability, IV) histopathological effects, V) atherosclerosis, VI) thrombosis, and VI) myocardial infarction. This review showed that animal model studies have been successful to bring new insights into the mechanisms underlying PM-induced cardiovascular diseases. However, there are some areas that the exact mechanisms are still unclear. In conclusion, investigating the cardiovascular effects of PM in vivo or interpreting the results should attempt to justify the role of different PM compositions, which may vastly affect the overall cytotoxicity of particles.

Saharan Dust Events in the Dust Belt -Canary Islands- and the Observed Association with in-Hospital Mortality of Patients with Heart Failure

Recent studies have found increases in the cardiovascular mortality rates during poor air quality events due to outbreaks of desert dust. In Tenerife, we collected (2014–2017) data in 829 patients admitted with a heart failure diagnosis in the Emergency Department of the University Hospital of the Canaries. In this region, concentrations of PM₁₀ and PM_2.5 are usually low (~20 and 10 µg/m³), but they increase to 360 and 115 μg/m³, respectively, during Saharan dust events. By using statistical tools (including multivariable logistic regressions), we compared in-hospital mortality of patients with heart failure and exposure to PM₁₀ and PM_2.5 during dust and no-dust events. We found that 86% of in-hospital heart failure mortality cases occurred during Saharan dust episodes that resulted in PM₁₀ > 50 µg/m³ (interquartile range: 71–96 µg/m³). A multivariate analysis showed that, after adjusting for other covariates, exposure to Saharan dust events associated with PM₁₀ > 50 µg/m³ was an independent predictor of heart failure in-hospital mortality (OR = 2.79, 95% CI (1.066–7.332), p = 0.03). In conclusion, this study demonstrates that exposure to high Saharan dust concentrations is independently associated with in-hospital mortality in patients with heart failure.

Diesel Exhaust Induces Mitochondrial Dysfunction, Hyperlipidemia, and Liver Steatosis

OBJECTIVE

Air pollution is associated with increased cardiovascular morbidity and mortality, as well as dyslipidemia and metabolic syndrome. Our goal was to dissect the mechanisms involved. Approach and Results: We assessed the effects of exposure to air pollution on lipid metabolism in mice through assessment of plasma lipids and lipoproteins, oxidized fatty acids 9-HODE (9-hydroxyoctadecadienoic) and 13-HODE (13-hydroxyoctadecadienoic), lipid, and carbohydrate metabolism. Findings were corroborated, and mechanisms were further assessed in HepG2 hepatocytes in culture. ApoE knockout mice exposed to inhaled diesel exhaust (DE, 6 h/d, 5 days/wk for 16 weeks) exhibited elevated plasma cholesterol and triglyceride levels, increased hepatic triglyceride content, and higher hepatic levels of 9-HODE and 13-HODE, as compared to control mice exposed to filtered air. A direct effect of DE exposure on hepatocytes was demonstrated by treatment of HepG2 cells with a methanol extract of DE particles followed by loading with oleic acid. As observed in vivo, this led to increased triglyceride content and significant downregulation of ACAD9 mRNA expression. Treatment of HepG2 cells with DE particles and oleic acid did not alter de novo lipogenesis but inhibited total, mitochondrial, and ATP-linked oxygen consumption rate, indicative of mitochondrial dysfunction. Treatment of isolated mitochondria, prepared from mouse liver, with DE particles and oleic acid also inhibited mitochondrial complex activity and β-oxidation.

CONCLUSIONS

DE exposure leads to dyslipidemia and liver steatosis in ApoE knockout mice, likely due to mitochondrial dysfunction and decreased lipid catabolism.

Potential role of polycyclic aromatic hydrocarbons as mediators of cardiovascular effects from combustion particles

Air pollution is the most important environmental risk factor for disease and premature death, and exposure to combustion particles from vehicles is a major contributor. Human epidemiological studies combined with experimental studies strongly suggest that exposure to combustion particles may enhance the risk of cardiovascular disease (CVD), including atherosclerosis, hypertension, thrombosis and myocardial infarction.In this review we hypothesize that adhered organic chemicals like polycyclic aromatic hydrocarbons (PAHs), contribute to development or exacerbation of CVD from combustion particles exposure. We summarize present knowledge from existing human epidemiological and clinical studies as well as experimental studies in animals and relevant in vitro studies. The available evidence suggests that organic compounds attached to these particles are significant triggers of CVD. Furthermore, their effects seem to be mediated at least in part by the aryl hydrocarbon receptor (AhR). The mechanisms include AhR-induced changes in gene expression as well as formation of reactive oxygen species (ROS) and/or reactive electrophilic metabolites. This is in accordance with a role of PAHs, as they seem to be the major chemical group on combustion particles, which bind AhR and/or is metabolically activated by CYP-enzymes. In some experimental models however, it seems as PAHs may induce an inflammatory atherosclerotic plaque phenotype irrespective of DNA- and/or AhR-ligand binding properties. Thus, various components and several signalling mechanisms/pathways are likely involved in CVD induced by combustion particles.We still need to expand our knowledge about the role of PAHs in CVD and in particular the relative importance of the different PAH species. This warrants further studies as enhanced knowledge on this issue may amend risk assessment of CVD caused by combustion particles and selection of efficient measures to reduce the health effects of particular matters (PM).

PM2.5 aggravates the lipid accumulation, mitochondrial damage and apoptosis in macrophage foam cells

Epidemiological evidence showed that the particulate matter exposure is associated with atherosclerotic plaque progression, which may be related to foam cell formation, but the mechanism is still unknown. The study was aimed to investigate the toxic effects and possible mechanism of PM_2.5 on the formation of macrophage foam cells induced by oxidized low density lipoprotein (ox-LDL). Results showed that PM_2.5 induced cytotoxicity by decreasing the cell viability and increasing the LDH level in macrophage foam cells. PM_2.5 aggravated the lipid accumulation in ox-LDL-stimulated macrophage RAW264.7 within markedly increasing level of intracellular lipid by Oil red O staining. The level of ROS increased obivously after co-exposure to PM_2.5 and ox-LDL than single exposure group. In addition, serious mitochondrial damage such as the mitochondrial swelling, cristae rupturing and disappearance were observed in macrophage foam cells. The loss of the mitochondrial membrane potential (MMP) further exacerbated the mitochondrial damage in PM_2.5-induced macrophage foam cells. The apoptotic rate increased more severely via up-regulated protein level of Bax, Cyt C, Caspase-9, Caspase-3, and down-regulated that of Bcl-2, indicating that PM_2.5 activated the mitochondrial-mediated apoptosis pathway. In summary, our results demonstrated that PM_2.5 aggravated the lipid accumulation, mitochondrial damage and apoptosis in macrophage foam cells, suggesting that PM_2.5 was a risk factor of atherosclerosis progression.

The cardiovascular protective effects of rooibos (Aspalathus linearis) extract on diesel exhaust particles induced inflammation and oxidative stress involve NF-κB- and Nrf2-dependent pathways modulation

Studies have shown that diesel exhaust particles (DEP) induced oxidative stress and inflammation. This present study examined the molecular effects of aqueous rooibos extract (RE) on the cardiovascular toxic effect of methanol extract of DEP in exposed Wistar rats. The results showed that DEP caused significant (p < 0.001) increase in MDA and CDs levels in the aorta and heart but this increase was significantly (p < 0.001) attenuated by rooibos extract. DEP induced IL-8, TNFα, IL-1β and decreased IL-10 gene expressions, all of which were reversed in the presence of rooibos extract. The expression of NF-κB, and IκKB genes were also significantly (p < 0.001) induced by DEP in both tissues, but pre-treatment with RE attenuated these effects. In contrast, DEP repressed IκB mRNA level, which was significantly (p < 0.001) reversed by rooibos extract pre-treatment. In addition, pre-treatment with rooibos extract attenuated the increased Nrf2 and HO-1 mRNA levels caused by DEP. This indicates the potential of rooibos extract to protect against DEP-induced cardiovascular toxicity.

Efficient and stable radiolabeling of polycyclic aromatic hydrocarbon assemblies: in vivo imaging of diesel exhaust particulates in mice

As a robust radioanalytical method for tracking carbonaceous particulates in vivo, polycyclic aromatic hydrocarbons from diesel exhaust were labeled with a radioactive-iodine-tagged pyrene analogue.

Ambient fine particulate matter exposure induces reversible cardiac dysfunction and fibrosis in juvenile and older female mice

BACKGROUND

Cardiovascular disease is the leading cause of mortality in the advanced world, and age is an important determinant of cardiac function. The purpose of the study is to determine whether the PM2.5-induced cardiac dysfunction is age-dependent and whether the adverse effects can be restored after PM2.5 exposure withdrawal.

METHODS

Female C57BL/6 mice at different ages (4-week-old, 4-month-old, and 10-month-old) received oropharyngeal aspiration of 3 mg/kg b.w. PM2.5 every other day for 4 weeks. Then, 10-month-old and 4-week-old mice were exposed to PM2.5 for 4 weeks and withdrawal PM2.5 1 or 2 weeks. Heart rate and systolic blood pressure were measured using a tail-cuff system. Cardiac function was assessed by echocardiography. Left ventricles were processed for histology to assess myocardial fibrosis. ROS generation was detected by photocatalysis using 2',7'-dichlorodihydrofluorescein diacetate (DCFHDA). The expression of cardiac fibrosis markers (Col1a1, Col3a1) and possible signaling molecules, including NADPH oxidase 4 (NOX-4), transforming growth factor β1 (TGFβ1), and Smad3, were detected by qPCR and/ or Western blot.

RESULTS

PM2.5 exposure induced cardiac diastolic dysfunction of mice, elevated the heart rate and blood pressure, developed cardiac systolic dysfunction of 10-month-old mice, and caused fibrosis in both 4-week-old and 10-month-old mice. PM2.5 exposure increased the expression of Col1a1, Col3a1, NOX-4, and TGFβ1, activated Smad3, and generated more reactive oxygen species in the myocardium of 4-week-old and 10-month-old mice. The withdrawal from PM2.5 exposure restored blood pressure, heart rate, cardiac function, expression of collagens, and malonaldehyde (MDA) levels in hearts of both 10-month-old and 4-week-old mice.

CONCLUSION

Juvenile and older mice are more sensitive to PM2.5 than adults and suffer from cardiac dysfunction. PM2.5 exposure reversibly elevated heart rate and blood pressure, induced cardiac systolic dysfunction of older mice, and reversibly induced fibrosis in juvenile and older mice. The mechanism by which PM2.5 exposure resulted in cardiac lesions might involve oxidative stress, NADPH oxidase, TGFβ1, and Smad-dependent pathways.