Exposure to ultrafine carbon particles at levels below detectable pulmonary inflammation affects cardiovascular performance in spontaneously hypertensive rats

In vitro neurotoxicity of particles from diesel and biodiesel fueled engines following direct and simulated inhalation exposure

Combustion-derived particulate matter (PM) is a major source of air pollution. Efforts to reduce diesel engine emission include the application of biodiesel. However, while urban PM exposure has been linked to adverse brain effects, little is known about the direct effects of PM from regular fossil diesel (PMDEP) and biodiesel (PMBIO) on neuronal function. Furthermore, it is unknown to what extent the PM-induced effects in the lung (e.g., inflammation) affect the brain. This in vitro study investigates direct and indirect toxicity of PMDEP and PMBIO on the lung and brain and compared it with effects of clean carbon particles (CP). PM were generated using a common rail diesel engine. CP was sampled from a spark generator. First, effects of 48 h exposure to PM and CP (1.2-3.9 µg/cm2) were assessed in an in vitro lung model (air-liquid interface co-culture of Calu-3 and THP1 cells) by measuring cell viability, cytotoxicity, barrier function, inflammation, and oxidative and cell stress. None of the exposures caused clear adverse effects and only minor changes in gene expression were observed. Next, the basal medium was collected for subsequent simulated inhalation exposure of rat primary cortical cells. Neuronal activity, recorded using microelectrode arrays (MEA), was increased after acute (0.5 h) simulated inhalation exposure. In contrast, direct exposure to PMDEP and PMBIO (1-100 µg/mL; 1.2-119 µg/cm2) reduced neuronal activity after 24 h with lowest observed effect levels of respectively 10 µg/mL and 30 µg/mL, indicating higher neurotoxic potency of PMDEP, whereas neuronal activity remained unaffected following CP exposure. These findings indicate that combustion-derived PM potently inhibit neuronal function following direct exposure, while the lung serves as a protective barrier. Furthermore, PMDEP exhibit a higher direct neurotoxic potency than PMBIO, and the data suggest that the neurotoxic effects is caused by adsorbed chemicals rather than the pure carbon core.

Indirect mediators of systemic health outcomes following nanoparticle inhalation exposure

The growing field of nanoscience has shed light on the wide diversity of natural and anthropogenic sources of nano-scale particulates, raising concern as to their impacts on human health. Inhalation is the most robust route of entry, with nanoparticles (NPs) evading mucociliary clearance and depositing deep into the alveolar region. Yet, impacts from inhaled NPs are evident far outside the lung, particularly on the cardiovascular system and highly vascularized organs like the brain. Peripheral effects are partly explained by the translocation of some NPs from the lung into the circulation; however, other NPs largely confined to the lung are still accompanied by systemic outcomes. Omic research has only just begun to inform on the complex myriad of molecules released from the lung to the blood as byproducts of pulmonary pathology. These indirect mediators are diverse in their molecular make-up and activity in the periphery. The present review examines systemic outcomes attributed to pulmonary NP exposure and what is known about indirect pathological mediators released from the lung into the circulation. Further focus was directed to outcomes in the brain, a highly vascularized region susceptible to acute and longer-term outcomes. Findings here support the need for big-data toxicological studies to understand what drives these health outcomes and better predict, circumvent, and treat the potential health impacts arising from NP exposure scenarios.

Inhalation of particulate matter containing free radicals leads to decreased vascular responsiveness associated with an altered pulmonary function

Airborne particulate matter (PM) is associated with an increased risk for cardiovascular diseases. Although the goal of thermal remediation is to eliminate organic wastes through combustion, when incomplete combustion occurs, organics chemisorb to transition metals to generate PM-containing environmentally persistent free radicals (EPFRs). Similar EPFR species have been detected in PM found in diesel and gasoline exhaust, woodsmoke, and urban air. Prior in vivo studies demonstrated that EPFRs reduce cardiac function secondary to elevations in pulmonary arterial pressures. In vitro studies showed that EPFRs increase ROS and cytokines in pulmonary epithelial cells. We thus hypothesized that EPFR inhalation would promote lung inflammation and oxidative stress, leading to systemic inflammation, vascular endothelial injury, and a decline in vascular function. Mice were exposed to EPFRs for either 4 h or for 4 h/day for 10 days and lung and vascular function were assessed. After a 4-h exposure, plasma nitric oxide (NO) was reduced while endothelin-1 (ET-1) was increased, however lung function was not altered. After 10 day, plasma NO and ET-1 levels were again altered and lung tidal volume was reduced. These time course studies suggested the vasculature may be an early target of injury. To test this hypothesis, an intermediate time point of 3 days was selected. Though the mice exhibited no marked inflammation in either the lung or the blood, we did note significantly reduced endothelial function concurrent with a reduction in lung tidal volume and an elevation in annexin V protein levels in the lung. Although vascular dysfunction was not dependent upon inflammation, it may be associated with an injury at the air-blood interface. Gene expression analysis suggested roles for oxidative stress and aryl hydrocarbon receptor (Ahr) signaling. Studies probing the relationship between pulmonary oxidative stress and AhR signaling at the air-blood interface with vascular dysfunction seem warranted.NEW & NOTEWORTHY Particulate matter (PM) resulting from the combustion of organic matter is known to contribute to cardiopulmonary disease. Despite hypotheses that cardiovascular dysfunction occurring after PM exposures is secondary to lung or systemic inflammation, these studies investigating exposures to PM-containing environmentally persistent free radicals (EPFRs) demonstrate that cardiovascular dysfunction precedes pulmonary inflammation. The cardiopulmonary health consequences of EPFRs have yet to be thoroughly evaluated, especially in healthy, adult mice. Our data suggest the vasculature as a direct target of PM exposure, and our studies aimed to elucidate the mechanisms contributing to EPFR-induced vascular dysfunction.

Carbon Nanotube Exposure Triggers a Cerebral Peptidomic Response: Barrier Compromise, Neuroinflammation, and a Hyperexcited State

The unique physicochemical properties of carbon nanomaterials and their ever-growing utilization generate a serious concern for occupational risk. Pulmonary exposure to these nanoparticles induces local and systemic inflammation, cardiovascular dysfunction, and even cognitive deficits. Although multiple routes of extrapulmonary toxicity have been proposed, the mechanism for and manner of neurologic effects remain minimally understood. Here, we examine the cerebral spinal fluid (CSF)-derived peptidomic fraction as a reflection of neuropathological alterations induced by pulmonary carbon nanomaterial exposure. Male C57BL/6 mice were exposed to 10 or 40 µg of multiwalled carbon nanotubes (MWCNT) by oropharyngeal aspiration. Serum and CSFs were collected 4 h post exposure. An enriched peptide fraction of both biofluids was analyzed using ion mobility-enabled data-independent mass spectrometry for label-free quantification. MWCNT exposure induced a prominent peptidomic response in the blood and CSF; however, correlation between fluids was limited. Instead, we determined that a MWCNT-induced peptidomic shift occurred specific to the CSF with 292 significant responses found that were not in serum. Identified MWCNT-responsive peptides depicted a mechanism involving aberrant fibrinolysis (fibrinopeptide A), blood-brain barrier permeation (homeobox protein A4), neuroinflammation (transmembrane protein 131L) with reactivity by astrocytes and microglia, and a pro-degradative (signal transducing adapter molecule, phosphoglycerate kinase), antiplastic (AF4/FMR2 family member 1, vacuolar protein sorting-associated protein 18) state with the excitation-inhibition balance shifted to a hyperexcited (microtubule-associated protein 1B) phenotype. Overall, the significant pathologic changes observed were consistent with early neurodegenerative disease and were diagnostically reflected in the CSF peptidome.

LKB1/p53/TIGAR/autophagy-dependent VEGF expression contributes to PM2.5-induced pulmonary inflammatory responses

One of the health hazards of PM2.5 exposure is to induce pulmonary inflammatory responses. In our previous study, we demonstrated that exposing both the immortalized and primary human bronchial epithelial cells to PM2.5 results in a significant upregulation of VEGF production, a typical signaling event to trigger chronic airway inflammation. Further investigations showed that PM2.5 exposure strongly induces ATR/CHK1/p53 cascade activation, leading to the induction of DRAM1-dependent autophagy to mediate VEGF expression by activating Src/STAT3 pathway. In the current study, we further revealed that TIGAR was another transcriptional target of p53 to trigger autophagy and VEGF upregulation in Beas-2B cells after PM2.5 exposure. Furthermore, LKB1, but not ATR and CHK1, played a critical role in mediating p53/TIGAR/autophagy/VEGF pathway activation also by linking to Src/STAT3 signaling cascade. Therefore, on combination of the previous report, we have identified both ATR/CHK1/p53/DRAM1- and LKB1/p53/TIGAR- dependent autophagy in mediating VEGF production in the bronchial epithelial cells under PM2.5 exposure. Moreover, the in vivo study further confirmed VEGF induction in the airway potentially contributed to the inflammatory responses in the pulmonary vascular endothelium of PM2.5-treated rats. Therefore, blocking VEGF expression or autophagy induction might be the valuable strategies to alleviating PM2.5-induced respiratory injuries.

Exposure of normal and chronic bronchitis-like mucosa models to aerosolized carbon nanoparticles: comparison of pro-inflammatory oxidative stress and tissue injury/repair responses

Carbon nanoparticles (CNP) are generated by incomplete combustion of diesel engines. Several epidemiological studies associated higher susceptibility to particulate matter related adverse respiratory outcomes with preexisting conditions like chronic bronchitis (CB). Therefore, we compared the effect of CNP exposure on primary bronchial epithelial cells (PBEC) developed in air-liquid interface (ALI) models of normal versus CB-like-mucosa.PBEC cultured at ALI represented normal mucosa (PBEC-ALI). To develop CB-like-mucosa (PBEC-ALI/CB), 1 ng/ml interleukin-13 was added to the basal media of PBEC-ALI culturing. PBEC-ALI and PBEC-ALI/CB were exposed to sham or to aerosolized CNP using XposeALI^® system. Protein levels of CXCL-8 and MMP-9 were measured in the basal media using ELISA. Transcript expression of pro-inflammatory (CXCL8, IL6, TNF, NFKB), oxidative stress (HMOX1, SOD3, GSTA1, GPx), tissue injury/repair (MMP9/TIMP1) and bronchial cell type markers (MUC5AC, CC10) were assessed using qRT-PCR.Increased secretion of CXCL-8 and MMP-9 markers was detected 24 h post-exposure in both PBEC-ALI and PBEC-ALI/CB with more pronounced effect in the later. Pro-inflammatory and tissue injury markers were increased at both 6 h and 24 h post-exposure in PBEC-ALI/CB. Oxidative stress markers exhibited similar responses at 6 h and 24 h post-exposure in PBEC-ALI/CB. The club cell specific marker CC10 was increased by 300 fold in PBEC-ALI/CB and 20 fold in PBEC-ALI following CNP exposure.Our data indicates an earlier and stronger reaction of pro-inflammatory, oxidative stress and tissue injury markers in PBEC-ALI/CB models compared to PBEC-ALI models following CNP exposure. The findings may provide insight into the plausible mechanisms of higher susceptibility among predisposed individuals to nanoparticle exposure.

Nanoparticle exposure driven circulating bioactive peptidome causes systemic inflammation and vascular dysfunction

Background

The mechanisms driving systemic effects consequent pulmonary nanoparticle exposure remain unclear. Recent work has established the existence of an indirect process by which factors released from the lung into the circulation promote systemic inflammation and cellular dysfunction, particularly on the vasculature. However, the composition of circulating contributing factors and how they are produced remains unknown. Evidence suggests matrix protease involvement; thus, here we used a well-characterized multi-walled carbon nanotube (MWCNT) oropharyngeal aspiration model with known vascular effects to assess the distinct contribution of nanoparticle-induced peptide fragments in driving systemic pathobiology.

Results

Data-independent mass spectrometry enabled the unbiased quantitative characterization of 841 significant MWCNT-responses within an enriched peptide fraction, with 567 of these factors demonstrating significant correlation across animal-paired bronchoalveolar lavage and serum biofluids. A database search curated for known matrix protease substrates and predicted signaling motifs enabled identification of 73 MWCNT-responsive peptides, which were significantly associated with an abnormal cardiovascular phenotype, extracellular matrix organization, immune-inflammatory processes, cell receptor signaling, and a MWCNT-altered serum exosome population. Production of a diverse peptidomic response was supported by a wide number of upregulated matrix and lysosomal proteases in the lung after MWCNT exposure. The peptide fraction was then found bioactive, producing endothelial cell inflammation and vascular dysfunction ex vivo akin to that induced with whole serum. Results implicate receptor ligand functionality in driving systemic effects, exemplified by an identified 59-mer thrombospondin fragment, replete with CD36 modulatory motifs, that when synthesized produced an anti-angiogenic response in vitro matching that of the peptide fraction. Other identified peptides point to integrin ligand functionality and more broadly to a diversity of receptor-mediated bioactivity induced by the peptidomic response to nanoparticle exposure.

Conclusion

The present study demonstrates that pulmonary-sequestered nanoparticles, such as multi-walled carbon nanotubes, acutely upregulate a diverse profile of matrix proteases, and induce a complex peptidomic response across lung and blood compartments. The serum peptide fraction, having cell-surface receptor ligand properties, conveys peripheral bioactivity in promoting endothelial cell inflammation, vasodilatory dysfunction and inhibiting angiogenesis. Results here establish peptide fragments as indirect, non-cytokine mediators and putative biomarkers of systemic health outcomes from nanoparticle exposure.

Instillation of particulate matter 2.5 induced acute lung injury and attenuated the injury recovery in ACE2 knockout mice

Inhaled particulate matter 2.5 (PM_2.5) can cause lung injury by inducing serious inflammation in lung tissue. Renin-angiotensin system (RAS) is involved in the pathogenesis of inflammatory lung diseases and regulates inflammatory response. Angiotensin-converting enzyme II (ACE2), which is produced through the angiotensin-converting enzyme (ACE)/angiotensin II (Ang II) axis, protects against lung disease. However, few studies have focused on the relationships between PM_2.5 and ACE2. Therefore, we aimed to explore the role of ACE2 in PM_2.5-induced acute lung injury (ALI). An animal model of PM_2.5-induced ALI was established with wild type (C57BL/6, WT) and ACE2 gene knockout (ACE2 KO) mice. The mice were exposed to PM_2.5 through intratracheal instillation once a day for 3 days (6.25 mg/kg/day) and then sacrificed at 2 days and 5 days after PM_2.5 instillation. The results show that resting respiratory rate (RRR), levels of inflammatory cytokines, ACE and MMPs in the lungs of WT and ACE2 KO mice were significantly increased at 2 days postinstillation. At 5 days postinstillation, the PM_2.5-induced ALI significantly recovered in the WT mice, but only partially recovered in the ACE2 KO mice. The results hint that PM_2.5 could induce severe ALI through pulmonary inflammation, and the repair after acute PM_2.5 postinstillation could be attenuated in the absence of ACE2. Additionally, our results show that PM_2.5-induced ALI is associated with signaling p-ERK1/2 and p-STAT3 pathways and ACE2 knockdown could increase pulmonary p-STAT3 and p-ERK1/2 levels in the PM_2.5-induced ALI.

IRE1α/XBP1s branch of UPR links HIF1α activation to mediate ANGII-dependent endothelial dysfunction under particulate matter (PM) 2.5 exposure

Short- and long-term exposure to particulate matter (PM) 2.5 instigates adverse health effect upon the cardiovascular (CV) system. Disclosing the molecular events by which PM2.5 evokes CV injuries is essential in developing effective risk-reduction strategy. Here we found that rats after intratracheally instillation with PM2.5 displayed increased circulating level of ANGII, the major bioactive peptide in renin-angiotensin-system (RAS), which resulted from the elevation of ANGII production in the vascular endothelium. Further investigations demonstrated that activation of IRE1α/XBP1s branch of unfolded protein response (UPR) was essential for augmented vascular ANGII signaling in response to PM2.5 exposure, whose effects strictly depends on the assembly of XBP1s/HIF1α transcriptional complex. Moreover, ablation of IRE1/XBP1/HIFα-dependent ACE/ANGII/AT1R axis activation inhibited oxidative stress and proinflammatory response in the vascular endothelial cells induced by PM2.5. Therefore, we conclude that PM2.5 exposure instigates endoplasmic reticulum instability, leading to the induction of IRE1α/XBP1s branch of UPR and links HIF1α transactivation to mediate ANGII-dependent endothelial dysfunction. Identifying novel therapeutic targets to alleviate ER stress and restore local RAS homeostasis in the endothelium may be helpful for the management of PM2.5-induced CV burden.

Early pulmonary response is critical for extra-pulmonary carbon nanoparticle mediated effects: comparison of inhalation versus intra-arterial infusion exposures in mice

Background

The death toll associated with inhaled ambient particulate matter (PM) is attributed mainly to cardio-vascular rather than pulmonary effects. However, it is unclear whether the key event for cardiovascular impairment is particle translocation from lung to circulation (direct effect) or indirect effects due to pulmonary particle-cell interactions. In this work, we addressed this issue by exposing healthy mice via inhalation and intra-arterial infusion (IAI) to carbon nanoparticles (CNP) as surrogate for soot, a major constituent of (ultrafine) urban PM.

Methods

Equivalent surface area CNP doses in the blood (30mm² per animal) were applied by IAI or inhalation (lung-deposited dose 10,000mm²; accounting for 0.3% of lung-to-blood CNP translocation). Mice were analyzed for changes in hematology and molecular markers of endothelial/epithelial dysfunction, pro-inflammatory reactions, oxidative stress, and coagulation in lungs and extra-pulmonary organs after CNP inhalation (4 h and 24 h) and CNP infusion (4 h). For methodological reasons, we used two different CNP types (spark-discharge and Printex90), with very similar physicochemical properties [≥98 and ≥95% elemental carbon; 10 and 14 nm primary particle diameter; and 800 and 300 m²/g specific surface area] for inhalation and IAI respectively.

Results

Mild pulmonary inflammatory responses and significant systemic effects were observed following 4 h and 24 h CNP inhalation. Increased retention of activated leukocytes, secondary thrombocytosis, and pro-inflammatory responses in secondary organs were detected following 4 h and 24 h of CNP inhalation only. Interestingly, among the investigated extra-pulmonary tissues (i.e. aorta, heart, and liver); aorta revealed as the most susceptible extra-pulmonary target following inhalation exposure. Bypassing the lungs by IAI however did not induce any extra-pulmonary effects at 4 h as compared to inhalation.

Conclusions

Our findings indicate that extra-pulmonary effects due to CNP inhalation are dominated by indirect effects (particle-cell interactions in the lung) rather than direct effects (translocated CNPs) within the first hours after exposure. Hence, CNP translocation may not be the key event inducing early cardiovascular impairment following air pollution episodes. The considerable response detected in the aorta after CNP inhalation warrants more emphasis on this tissue in future studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-017-0200-x) contains supplementary material, which is available to authorized users.

The heart as an extravascular target of endothelin-1 in particulate matter-induced cardiac dysfunction

Exposure to particulate matter air pollution has been causally linked to cardiovascular disease in humans. Several broad and overlapping hypotheses describing the biological mechanisms by which particulate matter exposure leads to cardiovascular disease have been explored, although linkage with specific factors or genes remains limited. These hypotheses may or may not also lead to particulate matter-induced cardiac dysfunction. Evidence pointing to autocrine/paracrine signaling systems as modulators of cardiac dysfunction has increased interest in the emerging role of endothelins as mediators of cardiac function following particulate matter exposure. Endothelin-1, a well-described small peptide expressed in the pulmonary and cardiovascular systems, is best known for its ability to constrict blood vessels, although it can also induce extravascular effects. Research on the role of endothelins in the context of air pollution has largely focused on vascular effects, with limited investigation of responses resulting from the direct effects of endothelins on cardiac tissue. This represents a significant knowledge gap in air pollution health effects research, given the abundance of endothelin receptors found on cardiac tissue and the ability of endothelin-1 to modulate cardiac contractility, heart rate, and rhythm. The plausibility of endothelin-1 as a mediator of particulate matter-induced cardiac dysfunction is further supported by the therapeutic utility of certain endothelin receptor antagonists. The present review examines the possibility that endothelin-1 release caused by exposure to PM directly modulates extravascular effects on the heart, deleteriously altering cardiac function.

The biological effects upon the cardiovascular system consequent to exposure to particulates of less than 500 nm in size

CONTEXT

Ultrafine particulate matter contribution to cardiovascular disease is not known and not regulated. PM up to 500 nm are abundant in urban air and alveolar deposition is significant.

OBJECTIVE

Effects beyond the alveolar barrier within the body or in vitro tissues exposed to particles <500 nm.

METHODS AND RESULTS

DATABASES

MEDLINE; Ovid-MEDLINE PREM; Web of Science; PubMed (SciGlobe). 127 articles. Results in tables: "subject type exposed", "exposure type", "technique".

CONCLUSION

Heart rate, vasoactivity, atherosclerotic advancement, oxidative stress, coagulability, inflammatory changes are affected. Production of reactive oxygen species is a useful target to limit outcomes associated with UFP exposure.

Metal rich particulate matter impairs acetylcholine-mediated vasorelaxation of microvessels in mice

Background

Exposure to PM_2.5 (particulate matter <2.5 μm) has been associated with changes in endothelial function. PM_2.5 was collected from two Chinese cities, Jinchang (JC) and Zhangye (ZH), both with similar PM_2.5 concentrations. However, JC had levels of nickel (Ni), selenium (Se), copper (Cu), and arsenic (As) that were 76, 25, 17, and 7 fold higher than that measured in ZH, respectively. We used this unique PM sample to delineate the chemical components that drive pulmonary and systemic effects and explore the mechanism(s) by which vascular dysfunction is caused.

Methods

Male FVB/N mice received oropharyngeal aspiration of water or PM_2.5 from JC, ZH or ZH spiked with one of the following elements at the same concentrations found in the JC PM (Ni = 4.76; As = 2.36; Se = 0.24; Cu = 2.43 μg/mg) followed by evaluation of markers of pulmonary and systemic inflammation. Mesenteric arteries were isolated for gene expression or functional response to various agonists (Phenylephrine, Acetylcholine, and Sodium Nitroprusside) and inhibitors (L-NAME, Apocynin, and VAS2870) ex vivo.

Results

Protein and total cell counts from lung lavage revealed significant pulmonary inflammation from ZH (p < 0.01) and JC and ZH + NiSO₄ (p < 0.001) as compared to control and a significant decrease in mesenteric artery relaxation (p < 0.001) and this decrease is blunted in the presence of NADPH oxidase inhibitors. Significant increases in gene expression (TNF-α, IL-6, Nos3; p < 0.01; NOX4; p < 0.05) were observed in JC and ZH + NiSO₄, as well as significantly higher concentrations of VEGF and IL-10 (p < 0.01, p < 0.001; respectively).

Conclusions

Our results indicate that the specific toxicity observed in PM from JC is likely due to the nickel component in the PM. Further, since VAS2870 was the most successful inhibitor to return vessels to baseline relaxation values, NADPH Oxidase is implicated as the primary source of PM-induced O₂^•-.

Air pollution and adverse cardiac remodeling: clinical effects and basic mechanisms

Exposure to air pollution has long been known to trigger cardiovascular events, primarily through activation of local and systemic inflammatory pathways that affect the vasculature. Detrimental effects of air pollution exposure on heart failure and cardiac remodeling have also been described in human populations. Recent studies in both human subjects and animal models have provided insights into the basic physiological, cellular and molecular mechanisms that play a role in adverse cardiac remodeling. This review will give a brief overview of the relationship between air pollution and cardiovascular disease, describe the clinical effects of air pollution exposure on cardiac remodeling, describe the basic mechanisms that affect remodeling as described in human and animal systems and will discuss future areas of investigation.

Ultrafine carbon particle mediated cardiovascular impairment of aged spontaneously hypertensive rats

Background

Studies provide compelling evidences for particulate matter (PM) associated cardiovascular health effects. Elderly individuals, particularly those with preexisting conditions like hypertension are regarded to be vulnerable. Experimental data are warranted to reveal the molecular pathomechanism of PM related cardiovascular impairments among aged/predisposed individuals. Thus we investigated the cardiovascular effects of ultrafine carbon particles (UfCP) on aged (12–13 months) spontaneously hypertensive rats (SHRs) and compared the findings with our pervious study on adult SHRs (6–7 months) to identify age related predisposition events in cardiovascular compromised elderly individuals.

Methods

Aged SHRs were inhalation exposed to UfCP for 24 h (~180 μg/m³) followed by radio-telemetric assessment for blood pressure (BP) and heart rate (HR). Bronchoalveolar lavage (BAL) fluid cell differentials, interleukin 6 (IL-6) and other proinflammatory cytokines; serum C-reactive protein (CRP) and haptoglobin (HPT); and plasma fibrinogen were measured. Transcript levels of hemeoxygenase 1 (HO-1), endothelin 1 (ET1), endothelin receptors A, B (ETA, ETB), tissue factor (TF), and plasminogen activator inhibitor-1 (PAI-1) were measured in the lung and heart to assess oxidative stress, endothelial dysfunction and coagulation cascade.

Result

UfCP exposed aged SHRs exhibited increased BP (4.4%) and HR (6.3%) on 1^st recovery day paralleled by a 58% increase of neutrophils and 25% increase of IL-6 in the BAL fluid. Simultaneously higher CRP, HPT and fibrinogen levels in exposed SHRs indicate systemic inflammation. HO-1, ET1, ET-A, ET-B, TF and PAI-1 were induced by 1.5-2.0 folds in lungs of aged SHRs on 1^st recovery day. However, in UfCP exposed adult SHRs these markers were up-regulated (2.5-6 fold) on 3^rd recovery day in lung without detectable pulmonary/systemic inflammation.

Conclusions

The UfCP induced pulmonary and systemic inflammation in aged SHRs is associated with oxidative stress, endothelial dysfunction and disturbed coagulatory hemostasis. UfCP exposure increased BP and HR in aged SHRs rats which was associated with lung inflammation, and increased expression of inflammatory, vasoconstriction and coagulation markers as well as systemic changes in biomarkers of thrombosis in aged SHRs. Our study provides further evidence for potential molecular mechanisms explaining the increased risk of particle mediated cardiac health effects in cardiovascular compromised elderly individuals.

Particulate matter beyond mass: recent health evidence on the role of fractions, chemical constituents and sources of emission

Particulate matter (PM) is regulated in various parts of the world based on specific size cut offs, often expressed as 10 or 2.5 µm mass median aerodynamic diameter. This pollutant is deemed one of the most dangerous to health and moreover, problems persist with high ambient concentrations. Continuing pressure to re-evaluate ambient air quality standards stems from research that not only has identified effects at low levels of PM but which also has revealed that reductions in certain components, sources and size fractions may best protect public health. Considerable amount of published information have emerged from toxicological research in recent years. Accumulating evidence has identified additional air quality metrics (e.g. black carbon, secondary organic and inorganic aerosols) that may be valuable in evaluating the health risks of, for example, primary combustion particles from traffic emissions, which are not fully taken into account with PM2.5 mass. Most of the evidence accumulated so far is for an adverse effect on health of carbonaceous material from traffic. Traffic-generated dust, including road, brake and tire wear, also contribute to the adverse effects on health. Exposure durations from a few minutes up to a year have been linked with adverse effects. The new evidence collected supports the scientific conclusions of the World Health Organization Air Quality Guidelines and also provides scientific arguments for taking decisive actions to improve air quality and reduce the global burden of disease associated with air pollution.

Particulate matter beyond mass: recent health evidence on the role of fractions, chemical constituents and sources of emission

Particulate matter (PM) is regulated in various parts of the world based on specific size cut offs, often expressed as 10 or 2.5 µm mass median aerodynamic diameter. This pollutant is deemed one of the most dangerous to health and moreover, problems persist with high ambient concentrations. Continuing pressure to re-evaluate ambient air quality standards stems from research that not only has identified effects at low levels of PM but which also has revealed that reductions in certain components, sources and size fractions may best protect public health. Considerable amount of published information have emerged from toxicological research in recent years. Accumulating evidence has identified additional air quality metrics (e.g. black carbon, secondary organic and inorganic aerosols) that may be valuable in evaluating the health risks of, for example, primary combustion particles from traffic emissions, which are not fully taken into account with PM2.5 mass. Most of the evidence accumulated so far is for an adverse effect on health of carbonaceous material from traffic. Traffic-generated dust, including road, brake and tire wear, also contribute to the adverse effects on health. Exposure durations from a few minutes up to a year have been linked with adverse effects. The new evidence collected supports the scientific conclusions of the World Health Organization Air Quality Guidelines and also provides scientific arguments for taking decisive actions to improve air quality and reduce the global burden of disease associated with air pollution.

Model of the deposition of aerosol particles in the respiratory tract of the rat. II. Hygroscopic particle deposition

BACKGROUND

Rats are frequently used to study the pharmacological and toxicological effects of inhaled aerosol particles. The deposition behavior of aerosol particles in airways is affected by their hygroscopic properties, which accordingly influence the results of such studies.

METHOD

A recently published nonhygroscopic aerosol particle deposition model for rat airways was extended with equations for hygroscopic particle growth in humid air and with a model to mimic the temperature and relative humidity conditions in the rat airways transformed from the upper human airways. As there are no experimental data available for hygroscopic deposition in rat lungs, several model assumptions were made for the humidity distribution in the upper rat airways.

RESULTS

The total and regional deposition probability of salt particles in the diameter range 0.02 to 5 μm in rat lung was significantly changed by the hygroscopic properties. The maximum ratios of the total deposition of inhaled initially dry sodium chloride, cobalt chloride, and zinc sulfate particles compared with nonhygroscopic particles were 3.28, 2.44, and 2.13, respectively, and the minimum ratios 0.57, 0.63, and 0.70, respectively. The corresponding maximum (and minimum) ratios for the hygroscopic drugs histamine dihydrochloride, carbenicillin disodium, and atropine sulfate were 1.86 (0.65), 1.53 (0.70), and 1.35 (0.76), respectively. Total deposition was about 20% higher in human airways than in rat airways. The flow regime in the rat upper airways influenced total and regional deposition much less than it did in human airways.

CONCLUSION

The hygroscopicity of salt and drug aerosol particles is an important factor in rat lung deposition.

Prevention and endothelial therapy of coronary artery disease

Functional integrity of endothelial cells is an indicator and a prerequisite for vascular health and counteracts the development of atherosclerosis. This concept of 'endothelial therapy' was developed in the late 1990s as an approach to preserve or restore endothelial cell health given that 'the knowledge of the mechanisms involved in 'endothelial dysfunction' allows us to interfere specifically with pathogenic pathways at very early time points and to slow down the progression of disease'. In the present review, the principles underlying endothelial cell health will be discussed as well as the role of endothelial therapy as a preventive measure to reduce the prevalence of coronary artery disease or to delay disease progression in patients with chronic coronary artery disease. This article also highlights the importance of active participation, the need to reduce the number of future patients in view of the rising prevalence of childhood obesity, and the potential of endothelial therapy to improve survival, reduce disability and health costs, and to improve overall quality of life in patients at risk for or already diagnosed with coronary artery disease. The preventive and therapeutic approaches and considerations described herein can be applied by physicians, patients, parents, educators, health agencies, and political decision makers to help reducing the global cardiovascular disease burden in the decades to come.

Evaluation of potential for toxicity from subacute inhalation of tire and road wear particles in rats

Tire and road wear particles (TRWP) are a component of ambient particulate matter (PM) produced from the interaction of tires with the roadway. Inhalation of PM has been associated with cardiopulmonary morbidities and mortalities thought to stem from pulmonary inflammation. To determine whether TRWP may contribute to these events, the effects of subacute inhalation of TRWP were evaluated in rats. TRWP were collected at a road simulator laboratory, aerosolized, and used to expose male and female Sprague-Dawley rats (n = 10/treatment group) at ~10, 40, or 100 μg/m³ TRWP via nose-only inhalation for 6 h/day for 28 days. Particle size distribution of the aerosolized TRWP was found to be within the respirable range for rats. Toxicity was assessed following OECD guidelines (TG 412). No TRWP-related effects were observed on survival, clinical observations, body or organ weights, gross pathology, food consumption, immune system endpoints, serum chemistry, or biochemical markers of inflammation or cytotoxicity. Rare to few focal areas of subacute inflammatory cell infiltration associated with TWRP exposure were observed in the lungs of one mid and four high exposure animals, but not the low-exposure animals. These alterations were minimal, widely scattered and considered insufficient in extent or severity to have an impact on pulmonary function. Furthermore, it is expected that these focal lesions would remain limited and may undergo resolution without long-term or progressive pulmonary alterations. Therefore, from this study we identified a no-observable-adverse-effect-level (NOAEL) of 112 μg/m³ of TRWP in rats for future use in risk assessment of TRWP.

From particles to patients: oxidative stress and the cardiovascular effects of air pollution

Air pollution, especially airborne particulate matter (PM), is associated with an increase in both morbidity and mortality from cardiovascular disease, although the underlying mechanisms remain incompletely established. The one consistent observation that links the pulmonary and cardiovascular effects of inhaled PM is oxidative stress. This article examines the evidence for the role of oxidative stress in the cardiovascular effects of air pollution, beginning with observations from epidemiological and controlled exposure studies and then exploring potential mechanistic pathways involving free radical generation from PM itself, to effects of PM on cell cultures, isolated organs, healthy animals and animal models of disease. Particular emphasis is placed on the vascular and atherosclerotic effects of urban air pollution and diesel exhaust emissions as rich sources of environmental ultrafine particles.

Particulate matter, air pollution, and blood pressure

A short-term increase in fine particulate matter air pollution (PM(2.5)) concentration increases the risk for myocardial infarctions, strokes, and heart failure exacerbations. An important mechanism likely contributing to these associations is an elevation in arterial blood pressure (BP). Exposure to ambient PM(2.5) even at present-day concentrations can increase BP within a period of a few days while long-term exposure might also promote the development of chronic hypertension. Controlled human and animal experiments have corroborated the veracity of these findings and elucidated plausible biological mechanisms. PM(2.5) deposition within the pulmonary tree is capable of rapidly triggering autonomic nervous system imbalance, thereby increasing BP within minutes of inhalation. In addition, fine particles can instigate a systemic pro-inflammatory response over a more prolonged period of exposure. Higher circulating levels of activated immune cells and inflammatory cytokines could consequently cause vascular endothelial dysfunction leading to an imbalance in vascular homeostatic responses. Indeed, chronic PM(2.5) exposure augments pro-vasoconstrictive pathways while blunting vasodilator capacity. Finally, certain particle constituents (e.g., metals, organic compounds, and ultra-fine particles) might also be capable of reaching the systemic circulation upon inhalation and thereafter directly impair vascular function. At the molecular level, the generation of oxidative stress with the consequent up-regulation of redox sensitive pathways appears to be a common and fundamental mechanism involved in the instigation of these pro-hypertensive responses. Due to the ubiquitous, continuous and often involuntary nature of exposure, PM(2.5) may be an important and under-appreciated worldwide environmental risk factor for increased arterial BP.

Manufactured and airborne nanoparticle cardiopulmonary interactions: a review of mechanisms and the possible contribution of mast cells

Human inhalation exposures to manufactured nanoparticles (NP) and airborne ultrafine particles (UFP) continues to increase in both occupational and environmental settings. UFP exposures have been associated with increased cardiovascular mortality and morbidity, while ongoing research supports adverse systemic and cardiovascular health effects after NP exposures. Adverse cardiovascular health effects include alterations in heart rate variability, hypertension, thrombosis, arrhythmias, increased myocardial infarction, and atherosclerosis. Exactly how UFP and NP cause these negative cardiovascular effects is poorly understood, however a variety of mediators and mechanisms have been proposed. UFP and NP, as well as their soluble components, are known to systemically translocate from the lung. Translocated particles could mediate cardiovascular toxicity through direct interactions with the vasculature, blood, and heart. Recent study suggests that sensory nerve stimulation within the lung may also contribute to UFP- and NP-induced acute cardiovascular alterations. Activation of sensory nerves, such as C-fibers, within the lung may result in altered cardiac rhythm and function. Lastly, release of pulmonary-derived mediators into systemic circulation has been proposed to facilitate cardiovascular effects. In general, these proposed pulmonary-derived mediators include proinflammatory cytokines, oxidatively modified macromolecules, vasoactive proteins, and prothrombotic factors. These pulmonary-derived mediators have been postulated to contribute to the subsequent prothrombotic, atherogenic, and inflammatory effects after exposure. This review will evaluate the potential contribution of individual mediators and mechanisms in facilitating cardiopulmonary toxicity following inhalation of UFP and NP. Lastly, we will appraise the literature and propose a hypothesis regarding the possible role of mast cells in contributing to these systemic effects.

Inhalation studies for the safety assessment of nanomaterials: status quo and the way forward

While technical and medical potential offered by nanotechnologies increase, the safety assessment of engineered nanomaterials (NMs) needs to follow this pace. Inhalation is a major route of occupational and environmental exposure, and is most relevant for most of the respective safety assessment studies. Control and generation of aerosol from the test materials for this route of administration are technically demanding, and not surprisingly, there are relatively few NMs tested in toxicokinetic, short-term, and subchronic inhalation studies. These studies were in part adapted to the peculiarities of inhaled NMs, but few were also conducted according to organization for economic co-operation and development (OECD) test guidelines. Inhalation studies on the potential to develop chronic diseases, or studies to check the potential analogy to cardiovascular diseases associated with adverse health effects from ambient air pollution, are largely missing. On the way forward, appropriate inhalation studies need to be performed on a number of NMs to assess their hazards and to provide a sound database for correlation and validation of alternative in vitro methods. Moreover, these studies can potentially aid in the grouping of different NMs based on their biokinetics or biological effects. For carcinogenic and cardiovascular effects, research studies are needed to verify-or disprove-the relevance and the mechanisms by which NMs contribute to these effects.

Combination effects of cigarette smoke extract and ambient ultrafine particles on endothelial cells

Previous studies have shown that ambient ultrafine particles with diameters less than 100nm (UFPs) can pass from the lungs to the circulation because of their very small diameter, and induce lung oxidative stress with a resultant dysfunction of lung endothelial cells. However, no studies have addressed the potential combined effects of UFPs and cigarette smoke on vascular endothelial cells. We hypothesized that co-exposure to UFPs and cigarette smoke extract (CSE) may cause combined effects on activation of endothelial cells and dysfunction of endothelium by oxidative stress through activation of NADPH oxidase. We determined the effects of UFPs with or without CSE on mouse pulmonary microvascular endothelial cells (MPMVEC) obtained from C57BL/6J (wild-type) and gp91(phox) knock-out mice (gp91(phox) is one of the key components of NADPH oxidase, one of ROS generators). Our results showed that exposure of MPMVEC from wild-type mice to UFPs or CSE, at a non-toxic dose, induced reactive oxygen species (ROS) generation, increased phosphorylation of p38 and Erk1/2, and up-regulated early growth response -1 (Egr-1) and IL-6 genes. These effects were significantly enhanced when cells were co-exposed to both UFPs and CSE. However, exposure of MPMVEC from gp91(phox) knock-out mice did not induce the above effects. Furthermore, UFPs- and/or CSE-induced Egr-1 mRNA upregulation was attenuated significantly when cells were pre-treated with p38 specific inhibitor, SB 203580, or MEK1/2 inhibitor, PD98059, and Egr-1 siRNA treatment abolished UFPs- and/or CSE-induced overexpression of IL-6. Our results suggest that UFPs and/or CSE caused activation of NADPH oxidase, resulting in ROS generation that led to activation of MAPKs through induced phosphorylation of p38 and ERK1/2 MAPKs and upregulation of Egr-1. Those effects may further result in endothelial dysfunction through production of cytokines such as IL-6. Our results suggest that co-exposure to UFPs and CSE causes enhanced injury to endothelial cells.

Inhaled nickel nanoparticles alter vascular reactivity in C57BL/6 mice

BACKGROUND

The use of nanoparticles (NPs) in technological applications is rapidly expanding, but the potential health effects associated with NP exposure are still largely unknown. Given epidemiological evidence indicating an association between inhaled ambient ultrafine particles and increased risk of cardiovascular disease morbidity and mortality, it has been suggested that exposure to NPs via inhalation may induce similar cardiovascular responses.

METHODS

Male C57BL/6 mice were exposed via whole-body inhalation to either filtered air (FA) or nickel hydroxide (NH) NPs (100, 150, or 900 µg/m(3)) for 1, 3, or 5 consecutive days (5 h/day). At 24-h post-exposure, vascular function in response to a vasoconstrictor, phenylephrine (PE), and a vasodilator, acetylcholine (ACh), was measured in the carotid artery.

RESULTS

Carotid arteries from mice exposed to all concentrations of NH-NPs showed statistically significant differences in graded doses of PE-induced contractile responses compared with those from FA mice. Similarly, vessels from NH-NP-exposed mice also demonstrated impaired vasorelaxation following graded doses of ACh as compared with FA mice.

CONCLUSIONS

These results suggest that short-term exposure to NH-NPs can induce acute endothelial disruption and alter vasoconstriction and vasorelaxation. These findings are consistent with other studies assessing vascular tone and function in the aorta, coronary, and mesenteric vessels from mice exposed to motor vehicular exhaust and concentrated ambient particles.

The procoagulant effects of fine particulate matter in vivo

Inhalation of fine particulate matter (<2.5 μm; fine PM) has been shown to increase the risk for cardiovascular events. In this letter, we reappraise the role of tissue factor (TF) antigen and we also summarize changes in measured coagulation proteins in humans and rodents by other studies with fine PM. By considering all studies including ours, we conclude that monitoring the overall coagulation state by measuring capacity assays such as thrombin generation, and quantification of TF activity would be more suitable than determining single coagulation proteins (such as TF antigen) in order to better assess the systemic prothrombotic effects of fine PM.

Cardiovascular and inflammatory effects of intratracheally instilled ambient dust from Augsburg, Germany, in spontaneously hypertensive rats (SHRs)

Rationale

Several epidemiological studies associated exposure to increased levels of particulate matter in Augsburg, Germany with cardiovascular mortality and morbidity. To elucidate the mechanisms of cardiovascular impairments we investigated the cardiopulmonary responses in spontaneously hypertensive rats (SHR), a model for human cardiovascular diseases, following intratracheal instillation of dust samples from Augsburg.

Methods

250 μg, 500 μg and 1000 μg of fine ambient particles (aerodynamic diameter <2.5 μm, PM_2.5-AB) collected from an urban background site in Augsburg during September and October 2006 (PM_2.5 18.2 μg/m³, 10,802 particles/cm³) were instilled in 12 months old SHRs to assess the inflammatory response in bronchoalveolar lavage fluid (BALF), blood, lung and heart tissues 1 and 3 days post instillation. Radio-telemetric analysis was performed to investigate the cardiovascular responses following instillation of particles at the highest dosage based on the inflammatory response observed.

Results

Exposure to 1000 μg of PM_2.5-AB was associated with a delayed increase in delta mean blood pressure (ΔmBP) during 2^nd-4^th day after instillation (10.0 ± 4.0 vs. -3.9 ± 2.6 mmHg) and reduced heart rate (HR) on the 3^rd day post instillation (325.1 ± 8.8 vs. 348.9 ± 12.5 bpm). BALF cell differential and inflammatory markers (osteopontin, interleukin-6, C-reactive protein, and macrophage inflammatory protein-2) from pulmonary and systemic level were significantly induced, mostly in a dose-dependent way. Protein analysis of various markers indicate that PM_2.5-AB instillation results in an activation of endothelin system (endothelin1), renin-angiotensin system (angiotensin converting enzyme) and also coagulation system (tissue factor, plasminogen activator inhibitor-1) in pulmonary and cardiac tissues during the same time period when alternation in ΔmBP and HR have been detected.

Conclusions

Our data suggests that high concentrations of PM_2.5-AB exposure triggers low grade PM mediated inflammatory effects in the lungs but disturbs vascular homeostasis in pulmonary tissues and on a systemic level by affecting the renin angiotensin system, the endothelin system and the coagulation cascade. These findings are indicative for promotion of endothelial dysfunction, atherosclerotic lesions, and thrombogeneis and, thus, provide plausible evidence that susceptible-predisposed individuals may develop acute cardiac events like myocardial infarction when repeatedly exposed to high pollution episodes as observed in epidemiological studies in Augsburg, Germany.

Platelet adhesion and fibrinogen deposition in murine microvessels upon inhalation of nanosized carbon particles

SUMMARY BACKGROUND

The translocation of nanoparticles in the lung toward effector organs via the circulation is considered an important direct pathway for systemic effects of nanoparticles after inhalation. Recently, we have reported that a moderate dose of systemically administered nanosized carbon black particles exerted thrombogenic effects in hepatic microvessels of healthy mice.

OBJECTIVES

This study addresses the questions of whether similar thrombogenic effects are also evoked upon inhalation of nanosized carbon particles (NCP) and whether NCP-induced hepatic platelet accumulation is associated with pulmonary or systemic inflammation.

METHODS

Two and 8 h after a 24-h exposure to either filtered air or to NCP, intravital fluorescence microscopy of the hepatic microcirculation was performed in C57Bl/6 mice. Parameters of pulmonary or systemic inflammatory response were determined in bronchoalveolar lavage and blood/plasma samples.

RESULTS

Inhalative exposure to NCP caused platelet accumulation in the hepatic microvasculature, whereas leukocyte recruitment and sinusoidal perfusion did not differ from controls. Fibrinogen deposition was detected by immunohistochemistry in both hepatic and cardiac microvessels from NCP-exposed mice. In contrast, inhalation of NCP affected neither the plasma levels of proinflammatory cytokines nor blood cell counts. Moreover, the bronchoalveolar lavage data indicate that no significant inflammatory response occurred in the lung.

CONCLUSIONS

Thus, exposure to NCP exerts thrombogenic effects in the microcirculation of healthy mice independent of the route of administration (i.e. inhalation or systemic intra-arterial administration). The NCP-induced thrombogenic effects are not liver specific, are associated with neither a local nor a systemic inflammatory response, and seem to be independent of pulmonary inflammation.

Regulation of plasminogen activator inhibitor-1 expression in endothelial cells with exposure to metal nanoparticles

Recent studies demonstrated that exposure to nanoparticles could enhance the adhesion of endothelial cells and modify the membrane structure of vascular endothelium. The endothelium plays an important role in the regulation of fibrinolysis, and imbalance of the fibrinolysis system potential contributes to the development of thrombosis. Plasminogen activator inhibitor-1 (PAI-1) is the most potent endogenous inhibitor of fibrinolysis and is involved in the pathogenesis of several cardiovascular diseases. The aim of this study was to investigate the alteration of PAI-1 expression in mouse pulmonary microvascular endothelial cells (MPMVEC) exposed to the metal nanoparticles that are known to be reactive, and the potential underlying mechanisms. We compared the alteration of PAI-1 expression in MPMVEC exposed to non-toxic doses of nano-size copper (II) oxide (Nano-CuO) and nano-size titanium dioxide (Nano-TiO(2)). Our results showed that Nano-CuO caused a dose- and time-dependent increase in PAI-1 expression. Moreover, exposure of MPMVEC to Nano-CuO caused reactive oxygen species (ROS) generation that was abolished by pre-treatment of cells with ROS scavengers or inhibitors, DPI, NAC and catalase. Exposure of MPMVEC to Nano-CuO also caused a dose- and time-dependent increase in p38 phosphorylation by Western blot. These effects were significantly attenuated when MPMVEC were pre-treated with DPI, NAC and catalase. To further investigate the role of p38 phosphorylation in Nano-CuO-induced PAI-1 overexpression, the p38 inhibitor, SB203580, was used to pre-treat cells prior to Nano-CuO exposure. We found that Nano-CuO-induced overexpression of PAI-1 was attenuated by p38 inhibitor pre-treatment. However, Nano-TiO(2) did not show the same results. Our results suggest that Nano-CuO caused up-regulation of PAI-1 in endothelial cells is mediated by p38 phosphorylation due to oxidative stress. These findings have important implications for understanding the potential health effects of metal nanoparticle exposure.

Particulate matter air pollution and cardiovascular disease: An update to the scientific statement from the American Heart Association

In 2004, the first American Heart Association scientific statement on "Air Pollution and Cardiovascular Disease" concluded that exposure to particulate matter (PM) air pollution contributes to cardiovascular morbidity and mortality. In the interim, numerous studies have expanded our understanding of this association and further elucidated the physiological and molecular mechanisms involved. The main objective of this updated American Heart Association scientific statement is to provide a comprehensive review of the new evidence linking PM exposure with cardiovascular disease, with a specific focus on highlighting the clinical implications for researchers and healthcare providers. The writing group also sought to provide expert consensus opinions on many aspects of the current state of science and updated suggestions for areas of future research. On the basis of the findings of this review, several new conclusions were reached, including the following: Exposure to PM <2.5 microm in diameter (PM(2.5)) over a few hours to weeks can trigger cardiovascular disease-related mortality and nonfatal events; longer-term exposure (eg, a few years) increases the risk for cardiovascular mortality to an even greater extent than exposures over a few days and reduces life expectancy within more highly exposed segments of the population by several months to a few years; reductions in PM levels are associated with decreases in cardiovascular mortality within a time frame as short as a few years; and many credible pathological mechanisms have been elucidated that lend biological plausibility to these findings. It is the opinion of the writing group that the overall evidence is consistent with a causal relationship between PM(2.5) exposure and cardiovascular morbidity and mortality. This body of evidence has grown and been strengthened substantially since the first American Heart Association scientific statement was published. Finally, PM(2.5) exposure is deemed a modifiable factor that contributes to cardiovascular morbidity and mortality.