2002 Progress Report: Pro-inflammatory and the Pro-oxidative Effects of Diesel Exhaust Particulate in Vivo and in Vitro

EPA Grant Number: R827352C002
Subproject: this is subproject number 002 , established and managed by the Center Director under grant R827352
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Southern California Particle Center and Supersite
Center Director: Froines, John R.
Title: Pro-inflammatory and the Pro-oxidative Effects of Diesel Exhaust Particulate in Vivo and in Vitro
Investigators: Nel, Andre E.
Current Investigators: Nel, Andre E. , Cho, Arthur K. , Froines, John R. , Li, Ning , Sioutas, Constantinos
Institution: University of California - Los Angeles , Michigan State University , University of California - Irvine , University of Southern California
Current Institution: University of California - Los Angeles , University of Southern California
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 31, 2005 (Extended to May 31, 2006)
Project Period Covered by this Report: June 1, 2001 through May 31, 2002
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air

Objective:

The overall objective of this research project is to focus on the central hypothesis of the Southern California Particle Center and Supersite, which is that organic constituents associated with particulate matter—including quinones, other organic compounds (polycyclic aromatic hydrocarbons [PAHs], nitro-PAHs, and aldehydes/ketones), and metals—are capable of generating reactive oxygen species (ROS) and acting as electrophilic agents. They have a central role in allergic airway disease such as asthma and cardiovascular effects through their ability to generate oxidative stress, inflammation, and immunomodulating effects in the lungs and airways.

The specific objectives of the research project are to: (1) establish a murine model for ovalbumin (OVA)-induced allergic inflammation and use that model for studying the adjuvant effects of the diesel exhaust particles (DEPs) on allergic inflammation; and (2) establish an in vitro model of toxicity in tissue culture macrophages and epithelial cells, in which the effects of particle composition can be studied in terms of oxidative stress effects, cytokine production, and induction of cytotoxicity (apoptosis).

We propose that the generation of oxidative stress in epithelial cells and macrophages leads to a hierarchical response, which is protective in nature, but may yield to injurious effects if the level of oxidative stress increases. We propose that the proinflammatory effects are responsible for the adjuvant effects of DEPs on allergic inflammation and asthma.

Progress Summary:

We have shown that it is possible to use aerosolized DEPs in an OVA inhalation-sensitization model to elicit adjuvant effects in terms of OVA-specific IgE and IgG1 antibody responses (Whitekus, 2002). This model, however, did not yield an increase in bronchoalveolar lavage eosinophils or an increase in airway hyperreactivity (AHR) as determined by whole body plethysmography. We concluded that combined DEP/allergen inhalation challenge is insufficient for achieving the sensitization threshold that is required to induce widespread allergic inflammation and AHR. Numerous attempts to develop a short-term animal model, in which DEPs exert adjuvant as well as AHR effects, failed. We did, however, notice that intraperitoneal OVA administration in the absence of alum can induce a state of mild allergen sensitization in which DEPs exert effects on AHR.

Because PM exposure can induce an acute asthma exacerbation, we developed protocols to study DEP effects on AHR, independent of the adjuvant effects of these particles. Three protocols were developed; two required OVA sensitization and the third was OVA independent. We demonstrated that DEPs could induce AHR in all three protocols.

We have extended the concept that the biological effects of DEPs are mediated through the generation of oxidative stress, providing evidence that a range of biological effects indicate a stratified oxidative stress response to DEP chemicals. In the past year, we have extended these concepts to study concentrated coarse, fine, and ultrafine particles (UFPs). In these studies, Dr. Sioutas used the Biosampler to collect "live" particles into tissue culture medium. We used these to show that different concentrated ambient particle (CAP) sizes exert differential biological effects in tissue culture macrophages and epithelial cells. UFPs were most potent towards inducing cellular heme oxygenase-1 (HO-1) expression and depleting intracellular glutathione. HO-1 expression, a sensitive marker for oxidative stress, is correlated directly to the high organic carbon and PAH content of UFPs. The dithiothreitol (DTT) assay, a quantitative measure of in vitro ROS formation, was correlated with PAH content and HO-1 expression. UFPs also had the highest ROS activity in the DTT assay. Because the small size of UFPs allows better tissue penetration, we used electron microscopy to study subcellular localization. UFPs, and to a lesser extent fine particles, localize in mitochondria where they induce major structural damage. This may contribute to oxidative stress. Our studies demonstrate that the increased biological potency of UFPs is related to the content of redox cycling organic chemicals and the ability to damage mitochondria. (This work was done in collaboration with Drs. Sioutas, Cho, Froines, and Miguel.)

Future Activities:

We will focus on further development of murine asthma models in Year 5 of the project. We will dissect the role of oxidative stress, airway inflammation, and irritant receptors on AHR. This will be accomplished by treating the animals with antioxidants, antiinflammatory drugs, and receptor blockers to determine the effects on airway obstruction and inflammation.

We will continue the in vitro DEP studies because methods development in these experiments will continue to refine biological hypotheses that can be applied to CAP studies. We will be working with Dr. Indira Venkatessen, who will use silica gel chromatography (Alsberg procedure) to provide us with aliphatic, aromatic, and polar materials to test in our cell culture experiments. These fractions will be tested for their effects on oxidative stress response pathways as well as for their ability to generate oxygen radicals in the DTT assay. We particularly are interested in studying the effects of these fractionated chemicals on the activation of the antioxidant response element (ARE).

Furthermore, we are interested in studying the notion that seasonal effects and temperature differences may influence the partitioning of semivolatile redox cycling chemicals on the particle surface, and that this may affect biological potency. Dr. Sioutas will collect fine and UFPs in the winter and summer months for comparison of their ability to induce oxidative stress, as determined by HO-1 expression, ARE-luciferase activity, and the ability to induce cytokine responses in epithelial cells in macrophages. We will attempt to correlate these biological responses with the chemical content of the particles and their ability to generate ROS in the DTT assay.

Journal Articles:

No journal articles submitted with this report: View all 15 publications for this subproject

Supplemental Keywords:

Particulate matter, quinones, PAHs, aldehydes, ketones, metals, allergic airway disease, human health risk, asthma, cardiovascular effects, oxidative stress, environmental monitoring, California, mobile sources, diesel exhaust particles, reactive oxygen species, in vitro modeling, antioxidant response element,, RFA, Health, Scientific Discipline, Air, Geographic Area, HUMAN HEALTH, particulate matter, Environmental Chemistry, Air Pollutants, State, Risk Assessments, Biochemistry, Health Effects, ambient aerosol, asthma, particulates, human health effects, toxicology, quinones, airway disease, diesel exhaust particulates, allergic airway disease, air pollution, diesel exhaust, PAH, human exposure, toxicity, particulate exposure, California (CA), allergens, aerosols, atmospheric chemistry, human health risk, particle transport, particle concentrator

Relevant Websites:

http://www.scpcs.ucla.edu/ exit EPA

Progress and Final Reports:

Original Abstract
  • 1999
  • 2000
  • 2001 Progress Report
  • 2003 Progress Report
  • 2004
  • Final Report

  • Main Center Abstract and Reports:

    R827352    Southern California Particle Center and Supersite

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827352C001 The Chemical Toxicology of Particulate Matter
    R827352C002 Pro-inflammatory and the Pro-oxidative Effects of Diesel Exhaust Particulate in Vivo and in Vitro
    R827352C003 Measurement of the “Effective” Surface Area of Ultrafine and Accumulation Mode PM (Pilot Project)
    R827352C004 Effect of Exposure to Freeways with Heavy Diesel Traffic and Gasoline Traffic on Asthma Mouse Model
    R827352C005 Effects of Exposure to Fine and Ultrafine Concentrated Ambient Particles near a Heavily Trafficked Freeway in Geriatric Rats (Pilot Project)
    R827352C006 Relationship Between Ultrafine Particle Size Distribution and Distance From Highways
    R827352C007 Exposure to Vehicular Pollutants and Respiratory Health
    R827352C008 Traffic Density and Human Reproductive Health
    R827352C009 The Role of Quinones, Aldehydes, Polycyclic Aromatic Hydrocarbons, and other Atmospheric Transformation Products on Chronic Health Effects in Children
    R827352C010 Novel Method for Measurement of Acrolein in Aerosols
    R827352C011 Off-Line Sampling of Exhaled Nitric Oxide in Respiratory Health Surveys
    R827352C012 Controlled Human Exposure Studies with Concentrated PM
    R827352C013 Particle Size Distributions of Polycyclic Aromatic Hydrocarbons in the LAB
    R827352C014 Physical and Chemical Characteristics of PM in the LAB (Source Receptor Study)
    R827352C015 Exposure Assessment and Airshed Modeling Applications in Support of SCPC and CHS Projects
    R827352C016 Particle Dosimetry
    R827352C017 Conduct Research and Monitoring That Contributes to a Better Understanding of the Measurement, Sources, Size Distribution, Chemical Composition, Physical State, Spatial and Temporal Variability, and Health Effects of Suspended PM in the Los Angeles Basin (LAB)