Final 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. , Cho, Arthur K. , Froines, John R. , Li, Ning , Sioutas, Constantinos
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)
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air

Objective:

Topic A: Studies Emphasizing Investigation of the Biological Mechanisms of Particulate Matter (PM) Effects in Relation to PM Physical and Chemical Characteristics

The objective of this project was to develop an understanding of the mechanisms by which PM induces adverse health effects, with particular emphasis on the role particulates play in the promotion of asthma and cellular immune function.

Summary/Accomplishments (Outputs/Outcomes):

Aim 1 was to elucidate the effects of diesel exhaust particulate (DEP) and ambient PM components on the generation of oxidative stress and inflammation in cellular studies performed in vitro. We demonstrated that DEP induces reactive oxygen species (ROS) production in macrophages and bronchial epithelial cells, and that these effects can be reproduced by methanol extracts made from these particles. ROS generation by pro-oxidative PM chemicals induced a hierarchical oxidative stress response in which a protective antioxidant defense (Tier 1) upgrades to pro-inflammatory (Tier 2) and cytotoxic effects (Tier 3) as the level of oxidative stress increases. An example of a Tier 1 antioxidant defense is the expression of HO-1. This gene is activated by the nuclear accumulation of Nrf2. This transcription factor drives the antioxidant response element (ARE) in the promoter of phase II enzymes, leading to increased expression of hemoxygenase-1, glutathione-S- transferase, NADPH quinone oxidoreductase, and catalase in DEP and PM-exposed macrophages and epithelial cells. HO-1, through its catabolic effect on heme, generates bilirubin and CO, which exerts antioxidant and cytoprotective effects. Escalation of oxidative stress to Tier 2, activates pro-inflammatory signaling pathways, e.g., the MAP kinase cascades. These cascades are involved in AP-1 transcriptional activity, leading to the expression of cytokines (e.g., IL-8) and adhesion molecules. At the highest level of oxidative stress (Tier 3), mitochondrial perturbation leads to the initiation of programmed cell death (apoptosis) and changes in mitochondrial morphology. Each tier of oxidative stress is sensitive to the effects of the thiol antioxidant, e.g., N-acetylcysteine.

An important extension was to investigate the role of specific redox cycling chemical groups, such as the polycyclic aromatic hydrocarbons (PAH) and quinones, in ROS generation. We performed silica gel chromatography on methylene chloride extracted DEP. After loading of the columns, aliphatic, aromatic and polar chemical fractions were eluted by increasing polar substances. We demonstrated that the quinone-enriched polar fraction was more active than the PAH-enriched aromatic fraction for its ability to redox cycle the DTT assay and to deplete glutathione in epithelial cells and macrophages. The aliphatic fraction was inactive in these assays. The relationship between the organic chemical composition and the redox cycling potential of PM was confirmed in a study where ultrafine particles (UF) were compared to coarse particles (C) and fine particles (F) collected in the LAB. UF were more active than C and F in the DTT assay, and also more effective in inducing oxidative stress in macrophages. Both the in vitro and cellular responses showed an excellent correlation with the PAH content of UF.

UF were found to lodge in mitochondria and disrupt the mitochondrial architecture. Functional effects on the permeability transition pore (PTP) and the mitochondrial membrane potential were confirmed in isolated mitochondrial preparations. Moreover, the UF effects on mitochondria could be reproduced by the polar and aromatic fractions prepared from DEP, while commercial nanoparticles were inactive. Together, these data show differential particle toxicity based on size, composition and subcellular localization.

Aim 2 was to use a murine model for asthma to study the effects of DEP on the enhancement of ovalbumin (OVA)-induced allergic inflammation and airway hyperreactivity (AHR). The asthma studies were premised on findings that DEP enhance allergen-specific IgE and TH2 cytokine production in humans and animals. We demonstrated that aerosolized DEP can enhance OVA-specific IgE production in a murine inhalation model. The adjuvant effect of DEP could be suppressed by NAC administration. While adequate for upregulating IgE production, an important limitation of this model was the inability of DEP to enhance AHR. This likely reflects the fact that oxidizing chemicals lead to efficient IgE gene rearrangement in deposition hotspots, but exposure did not exceed the threshold of airway inflammation that is required for AHR. DEP-induced AHR has now been achieved through modification of the classical mouse OVA sensitization model, in which sensitization is achieved by intraperitoneal administration of OVA. We developed two new protocols for OVA sensitization. In the low grade sensitization protocol, BALB/c mice received intraperitoneal OVA without alum, followed by challenge with aerosolized OVA ± DEP two weeks later. In the post-challenge model, DEP was delivered to classically sensitized animals a few days after the OVA challenge. Under both conditions, DEP enhanced airway inflammation to the point of exceeding the AHR threshold. Since these data suggest that low grade airway inflammation is required to elicit AHR, nebulized DEP was administered to mice which have been genetically engineered to overexpress IL-5. These animals exhibit constitutive airway inflammation, and responded to DEP inhalation with increased airway inflammation and AHR.

Conclusions:

PM exerts prooxidative effects in tissue culture cells and in the immune system that can be ascribed to the presence of the redox cycling chemicals. The particles also play an important role by acting as a vehicle for the delivery of the prooxidative chemicals. The particle size is of particular importance in being able to localize in and perturb cellular immune function. The biology of oxidative stress involves different levels of cellular responses, in which there is a dynamic equilibrium between the protective antioxidant defenses and pro-inflammatory and cytotoxic cellular responses. This dynamic equilibrium determines whether the cellular and immunological impact will be subclinical or can lead to allergic inflammation and asthma.

Technical Report:

Full Final Technical Report (PDF, 7pp., 49.5KB, about PDF)


Journal Articles on this Report : 15 Displayed | Download in RIS Format

Other subproject views: All 15 publications 15 publications in selected types All 15 journal articles
Other center views: All 138 publications 137 publications in selected types All 137 journal articles
Type Citation Sub Project Document Sources
Journal Article Chan RC-F, Wang M, Li N, Yanagawa Y, Onoe K, Lee JJ, Nel AE. Pro-oxidative diesel exhaust particle chemicals inhibit LPS-induced dendritic cell responses involved in T-helper differentiation. Journal of Allergy and Clinical Immunology 2006;118(2):455-465. R827352 (Final)
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  • Journal Article Hao M, Comier S, Wang M, Lee JJ, Nel A. Diesel exhaust particles exert acute effects on airway inflammation and function in murine allergen provocation models. Journal of Allergy and Clinical Immunology 2003;112(5):905-914. R827352 (2004)
    R827352 (Final)
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  • Journal Article Hiura TS, Li N, Kaplan R, Horwitz M, Seagrave J-C, Nel AE. The role of a mitochondrial pathway in the induction of apoptosis by chemicals extracted from diesel exhaust particles. Journal of Immunology 2000;165(5):2703-2711. R827352 (2004)
    R827352 (Final)
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  • Journal Article Li N, Venkatesan MI, Miguel A, Kaplan R, Gujuluva C, Alam J, Nel A. Induction of heme oxygenase-1 expression in macrophages by diesel exhaust particle chemicals and quinones via the antioxidant-responsive element. Journal of Immunology 2000;165(6):3393-3401. R827352 (2004)
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  • Journal Article Li N, Kim S, Wang M, Froines J, Sioutas C, Nel A. Use of a stratified oxidative stress model to study the biological effects of ambient concentrated and diesel exhaust particulate matter. Inhalation Toxicology 2002;14(5):459-486. R827352 (2004)
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  • Journal Article Li N, Sioutas C, Cho A, Schmitz D, Misra C, Sempf J, Wang M, Oberley T, Froines J, Nel A. Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage. Environmental Health Perspectives 2003;111(4):455-460. R827352 (2004)
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  • Journal Article Li N, Hao M, Phalen RF, Hinds WC, Nel AE. Particulate air pollutants and asthma: a paradigm for the role of oxidative stress in PM-induced adverse health effects. Clinical Immunology 2003;109(3):250-265. R827352 (2004)
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  • Journal Article Li N, Alam J, Venkatesan MI, Eiguren-Fernandez A, Schmitz D, Di Stefano E, Slaughter N, Killeen E, Wang X, Huang A, Wang M, Miguel AH, Cho A, Sioutas C, Nel AE. Nrf2 is a key transcription factor that regulates antioxidant defense in macrophages and epithelial cells:protecting against the proinflammatory and oxidizing effects of diesel exhaust chemicals. Journal of Immunology 2004;173(5):3467-3481. R827352 (2004)
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  • Abstract: Journal of Immunology-Abstract
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  • Journal Article Li N, Nel AE. Role of the Nrf2-mediated signaling pathway as a negative regulator of inflammation: implications for the impact of particulate pollutants on asthma. Antioxidants & Redox Signaling 2006;8(1-2):88-98. R827352 (Final)
    R827352C002 (Final)
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  • Journal Article Lippmann M, Frampton M, Schwartz J, Dockery D, Schlesinger R, Koutrakis P, Froines J, Nel A, Finkelstein J, Godleski J, Kaufman J, Koenig J, Larson T, Luchtel D, Liu L-JS, Oberdorster G, Peters A, Sarnat J, Sioutas C, Suh H, Sullivan J, Utell M, Wichmann E, Zelikoff J. The U.S. Environmental Protection Agency Particulate Matter Health Effects Research Centers Program: a midcourse report of status, progress, and plans. Environmental Health Perspectives 2003;111(8):1074-1092. R827352 (Final)
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  • Journal Article Nel AE, Diaz-Sanchez D, Li N. The role of particulate pollutants in pulmonary inflammation and asthma: evidence for the involvement of organic chemicals and oxidative stress. Current Opinion in Pulmonary Medicine 2001;7(1):20-26. R827352 (2004)
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  • Journal Article Nel AE. Air pollution-related illness: effects of particles. Science 2005;308(5723):804-806. R827352 (Final)
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  • Journal Article Whitekus MJ, Li N, Zhang M, Wang M, Horwitz MA, Nelson SK, Horwitz LD, Brechun N, Diaz-Sanchez D, Nel AE. Thiol antioxidants inhibit the adjuvant effects of aerosolized diesel exhaust particles in a murine model for ovalbumin sensitization. Journal of Immunology 2002;168(5):2560-2567. R827352 (Final)
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  • Journal Article Xia T, Korge P, Weiss JN, Li N, Venkatesan MI, Sioutas C, Nel A. Quinones and aromatic chemical compounds in particulate matter induce mitochondrial dysfunction: implications for ultrafine particle toxicity. Environmental Health Perspectives 2004;112(14):1347-1358. R827352 (Final)
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  • Journal Article Xia T, Kovochich M, Brant J, Hotze M, Sempf J, Oberley T, Sioutas C, Yeh JI, Wiesner MR, Nel AE. Comparison of the abilities of ambient and manufactured nanoparticles to induce cellular toxicity according to an oxidative stress paradigm. Nano Letters 2006;6(8):1794-1807. R827352 (Final)
    R827352C002 (Final)
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    R832413 (2008)
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    R832413C001 (2007)
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    R832413C002 (2006)
    R832413C002 (2008)
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  • Supplemental Keywords:

    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:

    Full Final Technical Report (PDF, 7pp., 49.5KB, about PDF)
    http://www.scpcs.ucla.edu Exit

    Progress and Final Reports:

    Original Abstract
  • 1999
  • 2000
  • 2001 Progress Report
  • 2002 Progress Report
  • 2003 Progress Report
  • 2004

  • 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)