2009 Progress Report: Human Clinical Studies of Concentrated Ambient Ultrafine and Fine Particles

EPA Grant Number: R832415C003
Subproject: this is subproject number 003 , established and managed by the Center Director under grant R832415
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Rochester PM Center
Center Director: Oberd√∂rster, G√ľnter
Title: Human Clinical Studies of Concentrated Ambient Ultrafine and Fine Particles
Investigators: Frampton, Mark W. , Zareba, Wojciech , Utell, Mark J. , Oakes, David , Phipps, Richard , Gelein, Robert
Institution: University of Rochester
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2012)
Project Period Covered by this Report: October 1, 2008 through September 30,2009
RFA: Particulate Matter Research Centers (2004) RFA Text |  Recipients Lists
Research Category: Human Health , Air

Objective:

The overall objective of our current and planned studies is to determine the pulmonary and cardiovascular effects of exposure to ultrafine and fine particulate matter (PM). The clinical studies in healthy humans and susceptible individuals with diabetes proposed in this research core focus on the effects of ambient ultrafine and fine particles on three major determinants of adverse cardiac events: 1) blood coagulation induced by effects on platelets and circulating microparticles; 2) cardiac output; and 3) cardiac rhythm and repolarization.
 
Our overall hypothesis is that inhalation of ambient PM causes small but measurable changes in coagulation and cardiovascular function that help explain the cardiovascular effects of PM exposure. We further hypothesize that the cardiovascular effects are determined by the ability of PM to generate reactive oxygen and nitrogen species, and are more pronounced in subjects with type 2 diabetes. Inhaled ultrafine particles increase the burden of reactive oxygen species to the endothelium. Endothelial activation and vasoconstriction increase platelet adherence and release of thromboxane, activate and prolong the transit time of blood leukocytes, and deplete vascular nitric oxide (NO). Particles may also have direct effects on platelets and leukocytes. Vascular injury triggers release of procoagulant microparticles into the blood, and initiation of coagulation. In collaboration with the Vascular and Inflammation Facility Core, we measure the effects of inhaled ambient fine PM on platelet number, phenotype, and function, and quantitate intravascular microparticles derived from platelets and endothelial cells. In collaboration with the Cardiac Core, we use noninvasive monitoring methods to measure exposure effects on cardiac output, rhythm, and repolarization. These studies take advantage of and extend upon our project funded by the National Institute of Environmental Health Sciences and the EPA, “Ultrafine Particle-Induced Oxidative Stress”, which focuses on effects on vascular function and NO.

Progress Summary:

1. Human clinical exposures to concentrated ambient ultrafine particles
We are completing data analysis for UPCON, our clinical study of healthy neversmoking subjects inhaling concentrated ambient UFP using the Harvard ultrafine particle concentrator system. This study is co-funded by an NIEHS R01 grant and this EPA center grant. Subjects were 20 healthy never-smokers, age 30 to 60 yrs, stratified by age and gender. Subjects were admitted to the Clinical Research Center the day prior to exposure, to minimize the potential influence of outdoor pollutant exposure in the hours prior to the experimental exposure. Physiologic measurements were made the day prior to exposure, and then 0, 3.5, 21, and 45 hours after exposure. Measurements included blood sampling for flow cytometry and soluble markers of inflammation and coagulation, pulmonary function testing, diffusing capacity for carbon monoxide, and flow-mediated dilatation of the forearm. The EPA Center is funding continuous cardiac monitoring, noninvasive measurement of cardiac output, and newly developed methods for analysis of platelet activation and circulating microparticles, using flow cytometry.
 
All 20 subjects completed both exposures. Exposures were successful from a technical standpoint, and no subject experienced symptoms or problems with the exposures.
 
Formal data analysis, in collaboration with our Biostatistical Core, has just been completed. We used a “mixed-models” approach for the analysis of cross-over trials with repeated measurements. We ran two models: model 1 examined the primary hypothesis of treatment (exposure) effects and contained terms for treatment, period, time, and time-bytreatment interactions; model 2 explored whether the exposure effects were different between males and females and between younger (age ≤ 45 years) and older (age > 45 years) subjects, and contained terms for treatment, gender, age group, treatment-by-gender interactions, and treatment-by-age interactions. Both models included adjustment for the corresponding baseline measurement prior to exposure in each period. The time variable in model 1 is a categorical variable, modeling the overall response trend over time within each period, and the time-by-treatment interactions examine the treatment effects over time.
 
We first examined the results from model 1, since it tested the primary hypothesis of treatment effects. We then examined the results of model 2, which considered the secondary hypothesis of treatment interactions by age and gender. Model 2 was considered exploratory, because the study was not adequately powered to test these interaction effects. Significance for both models was achieved by a p < 0.05.
 
Analysis confirmed a statistically significant UFP effect on blood pressure (BP). Figure 1 shows the increase in mean BP, which was statistically significant at 0.5 h after exposure (p=0.035). Diastolic BP increased more persistently. An increase in diastolic BP was greater in older compared with younger subjects (exposure-age interaction, p=0.034). The formal analysis also confirmed effects on lung function (Figure 2). There were small reductions in the FEV1 after UFP exposure (p=0.009). The olved close collaboration with R 1 after UFP relative to air exposure (p = 0.04), with the greatest effects in younger subjects (exposure-age interaction, p = 0.01) and in male subjects (exposure-gender interaction, p = 0.03). There were surprisingly few effects on heart rate variability or cardiac repolarization, and we did not find convincing effects on cardiac ventricular function (by impedance cardiography) or flow-mediated dilatation.
 
Figure 1. Change in mean blood pressure after exposure to air and UFP.
 
Figure 2. Change in FEV1 after exposure to air and UFP.
 
This project also involved close collaboration with Research Core #1 and the Aerosol Generation & Analysis Core for UFP concentration and exposure monitoring. Preliminary findings of this study were presented at the American Thoracic Society International Conference in May 2009. Manuscript preparation is underway.
 
2. Ultrafine Particle Effects on Dendritic Cells in Asthma (ASTHMACON)
 
We have just completed exposures as part of a pilot study that was funded in part by the Rochester EPA Center. This study represents a new focus of our group and our Center, on the potential effects of air pollution exposure on innate immunity in susceptible subjects. We hypothesized that, in susceptible asthmatic subjects, inhalation of concentrated ambient UFP will: 1) stimulate the recruitment and maturation of blood-derived dendritic cells (DC), 2) increase DC responses to challenge with bacterial products or PM, and 3) enhance the ability of DC to drive a Th2-type immune response. Furthermore, we hypothesized that these effects are most pronounced in those with genetic polymorphisms that reduce anti-oxidant defenses, specifically people who have the null variant of the glutathione S-transferase M1 (GSTM1) gene.
 
Our goal in this pilot study was to recruit and study 10 patients with asthma, 5 of whom were GSTM1 sufficient and 5 who were GSTM1 null. Subjects were exposed to concentrated ambient ultrafine particles on one occasion, on cleaned filtered air on another occasion, at rest. Exposures were separated by at least 3 weeks. At baseline and 3 and 24 hours after exposure, blood was obtained, spirometry was performed, and exhaled breath compensate was collected. Blood was subjected to a detailed flow cytometric characterization of circulating dendritic cells and monocytes. In addition, blood monocytes were cultured in vitro and stimulated to develop DC phenotypes. These blood derived dendritic cells were then challenged in vitro.
 
All 10 subjects have now completed the study, and data analysis is underway. Preliminary results indicate that UFP exposure caused subtle alterations in some subsets of circulating DCs. There were no effects on symptoms or lung function. Analysis of exhaled breath condensate is underway.

Future Activities:

We are in the planning and approval stages of our next clinical protocol, examining concentrated UFP effects in people with type 2 diabetes. This study will provide a comparison with our completed study in healthy subjects, and with our findings in diabetics exposed to elemental carbon UFP.
 
We are also completing our studies examining whether PM from various sources activates platelets in vitro.

Journal Articles:

No journal articles submitted with this report: View all 57 publications for this subproject

Supplemental Keywords:

RFA, Health, PHYSICAL ASPECTS, Scientific Discipline, Air, particulate matter, Health Risk Assessment, Risk Assessments, Physical Processes, atmospheric particulate matter, atmospheric particles, long term exposure, acute cardiovascular effects, airway disease, exposure, human exposure, ambient particle health effects, atmospheric aerosol particles, ultrafine particulate matter, PM, aersol particles, cardiovascular disease

Progress and Final Reports:

Original Abstract
  • 2006 Progress Report
  • 2007 Progress Report
  • 2008 Progress Report
  • 2010 Progress Report
  • 2011 Progress Report
  • Final Report

  • Main Center Abstract and Reports:

    R832415    Rochester PM Center

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R832415C001 Characterization and Source Apportionment
    R832415C002 Epidemiological Studies on Extra Pulmonary Effects of Fresh and Aged Urban Aerosols from Different Sources
    R832415C003 Human Clinical Studies of Concentrated Ambient Ultrafine and Fine Particles
    R832415C004 Animal models: Cardiovascular Disease, CNS Injury and Ultrafine Particle Biokinetics
    R832415C005 Ultrafine Particle Cell Interactions In Vitro: Molecular Mechanisms Leading To Altered Gene Expression in Relation to Particle Composition