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Insights into the mechanisms and mediators of the effects of air pollution exposure on blood pressure and vascular function in healthy humans.

ABSTRACT: Fine particulate matter air pollution plus ozone impairs vascular function and raises diastolic blood pressure. We aimed to determine the mechanism and air pollutant responsible. The effects of pollution on heart rate variability, blood pressure, biomarkers, and brachial flow-mediated dilatation were determined in 2 randomized, double-blind, crossover studies. In Ann Arbor, 50 subjects were exposed to fine particles (150 microg/m(3)) plus ozone (120 parts per billion) for 2 hours on 3 occasions with pretreatments of an endothelin antagonist (Bosentan, 250 mg), antioxidant (Vitamin C, 2 g), or placebo. In Toronto, 31 subjects were exposed to 4 different conditions (particles plus ozone, particles, ozone, and filtered air). In Toronto, diastolic blood pressure significantly increased (2.9 and 3.6 mm Hg) only during particle-containing exposures in association with particulate matter concentration and reductions in heart rate variability. Flow-mediated dilatation significantly decreased (2.0% and 2.9%) only 24 hours after particle-containing exposures in association with particulate matter concentration and increases in blood tumor necrosis factor alpha. In Ann Arbor, diastolic blood pressure significantly similarly increased during all of the exposures (2.5 to 4.0 mm Hg), a response not mitigated by pretreatments. Flow-mediated dilatation remained unaltered. Particulate matter, not ozone, was responsible for increasing diastolic blood pressure during air pollution inhalation, most plausibly by instigating acute autonomic imbalance. Only particles from urban Toronto additionally impaired endothelial function, likely via slower proinflammatory pathways. Our findings demonstrate credible mechanisms whereby fine particulate matter could trigger acute cardiovascular events and that aspects of exposure location may be an important determinant of the health consequences.

SUBMITTER: Brook RD

PROVIDER: S-EPMC3706996 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Insights into the mechanisms and mediators of the effects of air pollution exposure on blood pressure and vascular function in healthy humans.

Brook Robert D RD Urch Bruce B Dvonch J Timothy JT Bard Robert L RL Speck Mary M Keeler Gerald G Morishita Masako M Marsik Frank J FJ Kamal Ali S AS Kaciroti Niko N Harkema Jack J Corey Paul P Silverman Frances F Gold Diane R DR Wellenius Greg G Mittleman Murray A MA Rajagopalan Sanjay S Brook Jeffrey R JR

Hypertension (Dallas, Tex. : 1979) 20090720 3

Fine particulate matter air pollution plus ozone impairs vascular function and raises diastolic blood pressure. We aimed to determine the mechanism and air pollutant responsible. The effects of pollution on heart rate variability, blood pressure, biomarkers, and brachial flow-mediated dilatation were determined in 2 randomized, double-blind, crossover studies. In Ann Arbor, 50 subjects were exposed to fine particles (150 microg/m(3)) plus ozone (120 parts per billion) for 2 hours on 3 occasions ...[more]

PMID: 19620518

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Project description:BackgroundThere is a paucity of mechanistic information that is central to the understanding of the adverse health effects of source emission exposures. To identify source emission-related effects, blood and saliva samples from healthy volunteers who spent five days near a steel plant (Bayview site, with and without a mask that filtered many criteria pollutants) and at a well-removed College site were tested for oxidative stress, inflammation and endothelial dysfunction markers.MethodsBiomarker analyses were done using multiplexed protein-array, HPLC-Fluorescence, EIA and ELISA methods. Mixed effects models were used to test for associations between exposure, biological markers and physiological outcomes. Heat map with hierarchical clustering and Ingenuity Pathway Analysis (IPA) were used for mechanistic analyses.ResultsMean CO, SO2 and ultrafine particles (UFP) levels on the day of biological sampling were higher at the Bayview site compared to College site. Bayview site exposures "without" mask were associated with increased (p?<?0.05) pro-inflammatory cytokines (e.g IL-4, IL-6) and endothelins (ETs) compared to College site. Plasma IL-1?, IL-2 were increased (p?<?0.05) after Bayview site "without" compared to "with" mask exposures. Interquartile range (IQR) increases in CO, UFP and SO2 were associated with increased (p?<?0.05) plasma pro-inflammatory cytokines (e.g. IL-6, IL-8) and ET-1(1-21) levels. Plasma/saliva BET-1 levels were positively associated (p?<?0.05) with increased systolic BP. C-reactive protein (CRP) was positively associated (p?<?0.05) with increased heart rate. Protein network analyses exhibited activation of distinct inflammatory mechanisms after "with" and "without" mask exposures at the Bayview site relative to College site exposures.ConclusionsThese findings suggest that air pollutants in the proximity of steel mill site can influence inflammatory and vascular mechanisms. Use of mask and multiple biomarker data can be valuable in gaining insight into source emission-related health impacts.

Project description:BackgroundChildhood exposure to air pollution contributes to cardiovascular disease in adulthood. Immune and oxidative stress disturbances might mediate the effects of air pollution on the cardiovascular system, but the underlying mechanisms are poorly understood in adolescents. Therefore, we aimed to identify immune biomarkers linking air pollution exposure and blood pressure levels in adolescents.MethodsWe randomly recruited 100 adolescents (mean age, 16 years) from Fresno, California. Using central-site data, spatial-temporal modeling, and distance weighting exposures to the participant's home, we estimated average pollutant levels [particulate matter (PM), polyaromatic hydrocarbons (PAH), ozone (O3), carbon monoxide (CO) and nitrogen oxides (NOx)]. We collected blood samples and vital signs on health visits. Using proteomic platforms, we quantitated markers of inflammation, oxidative stress, coagulation, and endothelial function. Immune cellular characterization was performed via mass cytometry (CyTOF). We investigated associations between pollutant levels, cytokines, immune cell types, and blood pressure (BP) using partial least squares (PLS) and linear regression, while adjusting for important confounders.ResultsUsing PLS, biomarkers explaining most of the variance in air pollution exposure included markers of oxidative stress (GDF-15 and myeloperoxidase), acute inflammation (C-reactive protein), hemostasis (ADAMTS, D-dimer) and immune cell types such as monocytes. Most of these biomarkers were independently associated with the air pollution levels in fully adjusted regression models. In CyTOF analyses, monocytes were enriched in participants with the highest versus the lowest PM2.5 exposure. In both PLS and linear regression, diastolic BP was independently associated with PM2.5, NO, NO2, CO and PAH456 pollution levels (P ≤ 0.009). Moreover, monocyte levels were independently related to both air pollution and diastolic BP levels (P ≤ 0.010). In in vitro cell assays, plasma of participants with high PM2.5 exposure induced endothelial dysfunction as evaluated by eNOS and ICAM-1 expression and tube formation.ConclusionsFor the first time in adolescents, we found that ambient air pollution levels were associated with oxidative stress, acute inflammation, altered hemostasis, endothelial dysfunction, monocyte enrichment and diastolic blood pressure. Our findings provide new insights on pollution-related immunological and cardiovascular disturbances and advocate preventative measures of air pollution exposure.

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Insights into the mechanisms and mediators of the effects of air pollution exposure on blood pressure and vascular function in healthy humans.

Publications

Insights into the mechanisms and mediators of the effects of air pollution exposure on blood pressure and vascular function in healthy humans.

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