2012 Progress Report: Cardiovascular Consequences of Immune Modification by Traffic-Related Emissions

EPA Grant Number: R834796C003
Subproject: this is subproject number 003 , established and managed by the Center Director under grant R834796
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: University of Washington Center for Clean Air Research
Center Director: Vedal, Sverre
Title: Cardiovascular Consequences of Immune Modification by Traffic-Related Emissions
Investigators: Campen, Matthew J. , Lund, Amie K. , McDonald, Jacob D. , Rosenfeld, Michael
Current Investigators: Campen, Matthew J. , McDonald, Jacob D. , Rosenfeld, Michael
Institution: University of New Mexico , Lovelace Respiratory Research Institute , University of Washington
Current Institution: University of New Mexico , Lovelace Respiratory Research Institute , University of Washington , Washington State University
EPA Project Officer: Callan, Richard
Project Period: December 1, 2010 through November 30, 2015 (Extended to November 30, 2017)
Project Period Covered by this Report: December 1, 2011 through November 30,2012
RFA: Clean Air Research Centers (2009) RFA Text |  Recipients Lists
Research Category: Health Effects , Air

Objective:

Traffic-related emissions are associated with the incidence and progression of acute and chronic cardiovascular sequelae in human population studies. Such phenomena of near-roadway health effects have yet to be characterized toxicologically. Because of overlapping issues related to noise, socioeconomic status, ethnicity, etc., there is a need to better understand the biological plausibility that fresh mixtures of vehicular emissions have a more potent than expected impact on human health. We hypothesize that the complex mixtures produced by traffic are inherently more toxic due to the combined presence of both particulates and volatile organic emissions. Furthermore, we hypothesize that emissions-induced oxidation of certain endogenous phospholipids, presumably from the pulmonary surfactant, can stimulate the activity of immune cells through such receptors and in turn promote the invasion of existing vascular lesions.

Approach

This project will use complex roadway mixtures as generated and characterized in the laboratory.

Aim 1 - We will ascertain (1) the potentiating effects of physical and photochemical aging on fresh emissions and (2) interactions of vehicular emissions with pertinent co-pollutants (ozone, road dust), both in terms of driving systemic vascular oxidative stress.

Aim 2 - We will examine effects of the emissions-induced oxidative modifications to endogenous phospholipids, in terms of activating immune-modulating receptors such as LOX-1, CD-36, TLR-2, and TLR-4. This Aim will utilize transgenic models to examine the roles of these receptors, as well as characterize the lipidomic alterations in various tissues.

Aim 3 - We will further explore the role of specific immune cell populations of participants in the innate and adaptive responses to emissions-induced phospholipid modifications. In this Aim, we will utilize mouse models of immunodeficiency, including SCID and B-Cell deficient models. Additionally, we will pursue bone-marrow transplants from mice lacking those receptors described in Aim 2 to mechanistically establish the involvement of the oxidatively modified phospholipids.

Expected Results

Findings will: (1) indicate the most potent combinations of urban roadway and background co-pollutants in terms of vascular toxicity; and (2) detail the role of the immune system in mechanistically driving the systemic effects of inhaled pollutants.

Progress Summary:

First, we conducted 2 x 7-day exposures to MVE to ascertain our ability to discriminate vascular toxicity (oxidative stress, inflammation, toxicity) in our study permutations proposed in Aim 1. We compared between ApoE-/- and LDLR-/- mouse models on a high fat or normal chow diet at exposure levels of 100 and 300 μg PM/m3. Additionally, we compared lipid peroxidation in the vascular wall compared to perivascular fat. While our outcomes were more varied than we had previously observed (Lund et al., 2011), we felt confident that the most potent responses to mixed vehicular emissions (diesel + gasoline emissions) were in the perivascular fat of mice fed the high fat diet. It was not clear that the strain of mouse had a significant impact on the outcome, although the relative magnitude of effect was greater in LDLR-/- compared to ApoE-/- mice. While the outcome of this pilot work is of limited external value, it does go a long way towards helping us make decisions for future exposures, as was the plan for this Aim.

Figure 1. Lipid peroxidation from aortic vascular wall (left) or perivascular fat (right) from LDLR-/- or ApoE-/- mice on a low fat (LF) or high fat (HF) chow diet, exposed for 7d to mixed vehicular emissions. Trends highlight the importance of the perivascular fat in driving this and likely previously observed responses.

Upon sharing these data with the Scientific Advisory Committee, it was recommended that we explore several more sensitive and diverse markers of cellular redox stress. We have expanded our endpoints to include dihydroethidium staining (indicative of reactive oxygen species) and 3-nitrotyrosine staining (indicative of peroxynitrite formation).

Figure 2. Recently developed assays for detecting vascular reactive oxygen species (DHE staining, top slides) and reactive nitrogen species (antibody against 3-nitrotyrosine, colocalized to the endothelial marker von Willebrand Factor, pseudocolored orange).

Additionally, we have explored advanced in vivo imaging techniques to facilitate longitudinal assessment for changes in vascular and pulmonary inflammation and also cardiac function. To assess inflammation, a ligand to the leukocyte-function antigen (LFA-1) is linked to 111Indium via an Norbirt intermediate. This imaging construct is intravenously delivered and decays are detected by a small animal SPECT/CT system. Reconstruction of decays is linked to the CT image to provide anatomical reference. In a short pilot study, ApoE-/- mice were placed on a high fat chow for 2 weeks, then exposed to a week of 0.8 ppm O3 for 4h/d. Imaging revealed a consistent increase in cardiac and thoracic inflammation, likely as a result of the high fat diet, while ozone exposure induced a significant shift in rate of LFA-1 staining for both lungs and heart.

Simultaneously, we can image cardiac function by either 201Thallium or 99Tc-Sestamibi, which provide information on coronary flow/perfusion and, when paired with the timing information from an ECG record, allows function output of systolic and diastolic left ventricular volumes.

Combined, these new assays will provide a greater profile of toxicity and inflammation induced by the varied atmospheres proposed for Aims 1 and 2. We will be able to apply these to the exposures currently underway.

Figure 3. SPECT/CT imaging of vascular and pulmonary inflammation. ApoE-/- mice (N=5 per group) were placed on a high fat diet for 2 weeks, then exposed to 0.8 ppm ozone for 4h/d x 7d. Vascular inflammation was induced by the diet alone, but the addition of ozone exposure led to a noticeable increase in LFA-1 detection, especially in the carotid and aortic vessels.

Future Activities:

Aim 1: With 50 d exposures, continue a characterization of cardiovascular toxicity of the varied mixtures of gasoline and diesel emissions at different ratios.

Aim 2: Place double knockout models into exposures beginning late fall of 2012. We anticipate an initial study with ApoE-/-xTLR4-/- as our first undertaking, followed by ApoE-/-xCD36-/-.

Aim 3: The development of chimeric mice will wait until the end of the coming annual cycle, enabling exposures in year 4.


Journal Articles on this Report : 1 Displayed | Download in RIS Format

Other subproject views: All 20 publications 13 publications in selected types All 13 journal articles
Other center views: All 166 publications 74 publications in selected types All 73 journal articles
Type Citation Sub Project Document Sources
Journal Article Campen MJ, Lund A, Rosenfeld M. Mechanisms linking traffic-related air pollution and atherosclerosis. Current Opinion in Pulmonary Medicine 2012;18(2):155-160. R834796 (2012)
R834796 (2013)
R834796 (2015)
R834796C003 (2012)
R834796C003 (2013)
R833990 (2010)
R833990 (2011)
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  • Supplemental Keywords:

    coronary artery disease, oxidized phospholipids, atherosclerosis, particulate matter, volatile organic compounds, carbon monoxide, ozone;, Scientific Discipline, Health, Air, ENVIRONMENTAL MANAGEMENT, Air Quality, air toxics, Health Risk Assessment, Risk Assessments, mobile sources, Environmental Monitoring, Biochemistry, Risk Assessment, ambient air quality, atmospheric particulate matter, particulate matter, aerosol particles, air pollutants, motor vehicle emissions, vehicle emissions, air quality models, motor vehicle exhaust, airway disease, bioavailability, air pollution, particle exposure, atmospheric aerosols, ambient particle health effects, vascular dysfunction, cardiotoxicity, atmospheric chemistry, exposure assessment

    Progress and Final Reports:

    Original Abstract
    2011 Progress Report
    2013 Progress Report
    2015 Progress Report
    2016 Progress Report


    Main Center Abstract and Reports:

    R834796    University of Washington Center for Clean Air Research

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R834796C001 Exposure Mapping – Characterization of Gases and Particles for ExposureAssessment in Health Effects and Laboratory Studies
    R834796C002 Simulated Roadway Exposure Atmospheres for Laboratory Animal and Human Studies
    R834796C003 Cardiovascular Consequences of Immune Modification by Traffic-Related Emissions
    R834796C004 Vascular Response to Traffic-Derived Inhalation in Humans
    R834796C005 Effects of Long-Term Exposure to Traffic-Derived Particles and Gases on Subclinical Measures of Cardiovascular Disease in a Multi-Ethnic Cohort