2003 Progress Report: Lung Hypoxia as Potential Mechanisms for PM-Induced Health Effects

EPA Grant Number: R827351C010
Subproject: this is subproject number 010 , established and managed by the Center Director under grant R827351
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EPA NYU PM Center: Health Risks of PM Components
Center Director: N/A
Title: Lung Hypoxia as Potential Mechanisms for PM-Induced Health Effects
Investigators: Salnikow, Konstantin
Current Investigators: Cohen, Mitchell , Salnikow, Konstantin
Institution: New York University School of Medicine
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, 2002 through May 31, 2003
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air

Objective:

Ambient particulate matter (PM) originating from many natural and anthropogenic sources often contains relatively high quantities of transition metals, predominantly iron (Fe), nickel (Ni), vanadium (V), aluminum (Al), magnesium (Mg), calcium (Ca), chromium (Cr), and nickel (Ni), with levels of each varying depending on the particle source. At-risk individuals with preexisting hypertensive diesease/atherosclerosis appear to have overtly negative responses to exposure to PM. Both the mechanisms underlying these effects and the constituents in PM that might be causing these outcomes, however, remain unclear. Because atherosclerosis more recently has been designated as a chronic inflammatory process, it has been accepted that circulating levels of interleukin (IL)-6 may reflect the intensity of occult plaque inflammation and vulnerability to rupture. In addition, both monocyte chemoattractant protein-1 (MCP-1) and IL-8 may play a crucial role in initiating and promoting atherosclerosis by recruiting monocytes/macrophages to the vessel wall, thereby enhancing the development of atherosclerotic lesions and plaque. Several atherogenic factors induce these cytokines in cardiovascular tissues, primarily through the activation of transcription factors such as NF-ĸB or peroxisome proliferator-activated receptors. In contrast, IL-10 exerts antiinflammatory effects, possibly by deactivating proinflammatory cytokines and inducible nitric oxide synthase. Hypertensive patients are at particular risk of cardiovascular complications, possibly related to endothelial damage or dysfunction or to abnormal angiogenesis. These pathophysiologic processes are correlatable with plasma levels of vascular endothelial growth factor (VEGF); plasma VEGF levels are higher in hypertensive patients compared with control individuals and correlate significantly with age, systolic and diastolic blood pressure, 10-year cardiovascular disease, and cerebrovascular accident risk scores.

We previously hypothesized that select constituents within PM (i.e., Al, V, Ni, and manganese [Mn]) act on epithelial cells and resident macrophages in the lungs such that they are stimulated to release proinflammatory cytokines/chemokines, including those cited above in the initiation and/or promotion of atherosclerosis. The objective of this research project is to investigate the hypothesis that these specific metals in PM contribute to the aforementioned deleterious responses in patients with preexisting hypertensive diesease/atherosclerosis by a priori altering the Fe status of these cells, which in turn results in the increased intracellular accumulation of hypoxia-inducible factor-1α (HIF-1α). It is as a result of this increase in the latter that lung epithelial cells and macrophages then are stimulated to increase their formation/release of proinflammatory cytokines such as IL-6, IL-8, and tumor necrosis factor-α, as well as MCP-1 and VEGF, that then are transported rapidly to the heart in still relatively high undiluted concentrations (as opposed to levels measurable after dilution in the general systemic circulation).

This is one of the projects funded by the New York University (NYU) PM Center. The progress for the other projects is reported separately (see reports for R827351C001 through R827351C009, and R827351C011 through R827351C016).

Progress Summary:

To validate our hypothesis, lung macrophage and airway epithelium cell lines are exposed to varying amounts of Fe alone or in combination with Al, V, Mn, or Ni (at levels relevant to those found in ambient urban PM from New York City [NYC]), and levels of each of the above cited cytokines/chemokines are measured by enzyme-linked immunosorbent assay (ELISA), and Northern and Western analyses (the latter to increase the degree of detectability of effects from the treatments). These results then will be used as a baseline of effects for later comparison against the actual formation of these proteins in the lungs of rodents exposed to the “parent” NYC PM2.5 samples.

Progress in Years 1 and 2 of the Project (Years 4 and 5 of the Center)

Because it recently was shown that water soluble Ni was responsible for a majority of the pulmonary injury caused by residual oil fly ash (ROFA) and that pulmonary inflammation induced by ROFA was reproducible by instillation of soluble forms of Ni (i.e., nickel chloride, nickel sulfate, or nickel sulfide), our initial studies examined the potential effects of Fe and Ni (alone and in combination) on hypoxic stress induction and IL-8 production in the human lung epithelial 1HAEo- cell line. Exposure to Ni produced hypoxic stress as measured by induction of hypoxia-inducible N-myc downstream-regulated gene l and significantly induced cell production of IL-8. Similarly, hypoxic stress and IL-8 production were induced by the Fe chelator desferoxamine (DFX), suggesting that Ni interfered with the Fe status of the cells. It is possible that Ni inside the cell may have become substituted for Fe in Fe-containing enzymes/proteins, which in turn led to inhibition of their activity and the activation/induction of HIF-1α transcription factors. Conversely, it is possible that the Ni caused Fe entry into the cells to be impacted, much in the manner observed with other PM-associated metals in the ongoing Center study of Mitchell Cohen (R827351C008). Preliminary studies using the iron regulatory protein activation parameter have indicated that treatment of rat lung macrophages with PM-relevant levels of Ni in conjunction with Fe caused a deficit in cell levels of the Fe.

To determine if treatment of the 1HAEo- or rat NR8383 macrophages with some of the PM-associated metals shown here and in project number R827351C008 to cause alterations in Fe homeostasis induce HIF-1α expression and subsequently increase the presence/release of factors such as macrophage inflammatory protein 2 (MIP-2)/IL-8 or VEGF, cultures of each line were treated overnight with various amounts of soluble forms of Ni, V, or Al in combination with a fixed amount of Fe (each at levels that would reflect amounts that would have been encountered in 500 µg of NYC PM2.5 from a random day in October 2001). Analysis of cellular products by Western blots indicated that increases in the relative amounts of V to Fe caused significant increases in expression of HIF-1α in the NR cells (to values similar to those induced by DFX). Exposure to increasing amounts of Ni also caused increased HIF-1α expression, but less so than with V. Al treatments appeared to have no effect on HIF-1α expression; however, as these exposures resulted in more cell death and proteolytic damage to materials isolated from viable cells, these measurements may have been biased.

Analyses of the HIF-1α-inducible cytokines/chemokines indicated that Al, Ni, and V each induced VEGF formation in NR cells; the strength of this effect was Al ≥ Ni > V. In each case, induction levels were near equivalent to that from DFX treatment. Western analyses of MIP-2 levels in NR cells have been inconclusive, primarily as a result of the difficulty in trying to resolve adequately the 8 Kd protein from the lysates isolated from treated cells. ELISAs being performed to estimate how much MIP-2 potentially is released from treated cells have yielded preliminary indications that, of the three metals, Al has the strongest impact on MIP-2 release by the NR line. With the 1HAEo- line, ELISAs performed on the supernatants of cells treated with Al, Ni, or V have suggested that at the higher levels (relative to the fixed Fe level) tested, each metal could cause a strong induction in IL-8 formation/release. In contrast, any stimulation of VEGF production by the cells appeared only to occur with an increasing presence of Ni. Western analyses to confirm these patterns are being performed; however, problems of poor specificity by the commercial antibodies have hindered these determinations from being made at this time.


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

Other subproject views: All 3 publications 3 publications in selected types All 3 journal articles
Other center views: All 112 publications 101 publications in selected types All 89 journal articles
Type Citation Sub Project Document Sources
Journal Article Salnikow K, Li X, Lippmann M. Effect of nickel and iron co-exposure on human lung cells. Toxicology and Applied Pharmacology 2004;196(2):258-265. R827351 (2003)
R827351 (Final)
R827351C010 (2003)
R827351C010 (Final)
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  • Supplemental Keywords:

    thoracic particles, PM10, fine particles, PM2.5, ultrafine particles, PM 0.1, lung dosimetry models, human exposure models, pulmonary responses, cardiovascular responses, immunological responses, criteria air pollutants, concentrated ambient aerosols, aerosol, air pollutants, air pollution, airborne pollutants, airway disease, airway inflammation, airway variability, allergen, ambient air, ambient air quality, analytical chemistry, assessment of exposure, asthma, asthma morbidity, atmospheric monitoring, biological markers, childhood respiratory disease, children, combustion, combustion contaminants, combustion emissions, compliance monitoring, dosimetry, epidemiology, exposure, exposure and effects, health effects, heart rate variability, human exposure, human health, human health effects, incineration, lead, lung, mercury, morbidity, particulates, pulmonary, pulmonary disease, respiratory,, RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, ENVIRONMENTAL MANAGEMENT, particulate matter, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Environmental Monitoring, Physical Processes, Atmospheric Sciences, Risk Assessment, ambient air quality, atmospheric particulate matter, particulates, atmospheric particles, chemical characteristics, toxicology, ambient air monitoring, acute lung injury, airborne particulate matter, environmental risks, exposure, epidemelogy, lung hypoxia, air pollution, aerosol composition, atmospheric aerosol particles, pulmonary hypertension, human exposure, PM, airway contractile properties, exposure assessment

    Relevant Websites:

    http://www.med.nyu.edu/environmental/centers/epa/ Exit

    Progress and Final Reports:

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

  • Main Center Abstract and Reports:

    R827351    EPA NYU PM Center: Health Risks of PM Components

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827351C001 Exposure Characterization Error
    R827351C002 X-ray CT-based Assessment of Variations in Human Airway Geometry: Implications for Evaluation of Particle Deposition and Dose to Different Populations
    R827351C003 Asthma Susceptibility to PM2.5
    R827351C004 Health Effects of Ambient Air PM in Controlled Human Exposures
    R827351C005 Physicochemical Parameters of Combustion Generated Atmospheres as Determinants of PM Toxicity
    R827351C006 Effects of Particle-Associated Irritants on the Cardiovascular System
    R827351C007 Role of PM-Associated Transition Metals in Exacerbating Infectious Pneumoniae in Exposed Rats
    R827351C008 Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron Status
    R827351C009 Health Risks of Particulate Matter Components: Center Service Core
    R827351C010 Lung Hypoxia as Potential Mechanisms for PM-Induced Health Effects
    R827351C011 Urban PM2.5 Surface Chemistry and Interactions with Bronchoalveolar Lavage Fluid (BALF)
    R827351C012 Subchronic PM2.5 Exposure Study at the NYU PM Center
    R827351C013 Long Term Health Effects of Concentrated Ambient PM2.5
    R827351C014 PM Components and NYC Respiratory and Cardiovascular Morbidity
    R827351C015 Development of a Real-Time Monitoring System for Acidity and Soluble Components in Airborne Particulate Matter
    R827351C016 Automated Real-Time Ambient Fine PM Monitoring System