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Final Report: Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron Status
EPA Grant Number: R827351C008Subproject: this is subproject number 008 , 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: Lippmann, Morton
Title: Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron Status
Investigators: Cohen, Mitchell
Institution: NYU School of Medicine
EPA Project Officer: Stacey Katz/Gail Robarge,
Project Period: June 1, 1999 through May 31, 2005 (Extended to May 31, 2006)
RFA: Airborne Particulate Matter (PM) Centers (1999)
Research Category: Particulate Matter
Description:
Objective:PM2.5 induces/exacerbates infectious lung disease and alters the manner by which lungs handle bacteria. This project sought to validate the hypotheses that: 1) PM2.5 modulates lung phagocyte antibacterial function by altering cellular Fe status; 2) metals (rather than organics, biomatter) in PM2.5 underlay any change in lung leukocyte Fe status; and 3) relative Fe content in PM2.5 governs these effects, i.e, a presence of relatively greater levels (with respect to Fe) of competitor metals for transferrin (Tf) binding (e.g., Al, Mn, or V) brings about reduced antibacterial function due to reduced endogenous Fe transport to the cells. The study objectives were: 1) in cooperation with Los Angeles and Seattle PM Centers, to collect and characterize patterns of proportionality of Al, Mn, and V to Fe in daily PM2.5 samples in each city over a 3-mo period; 2) to determine in vitro if a presence of Al, Mn, and V impacted on Fe homeostasis in a rat lung macrophage cell line (i.e., NR8383) were used; and 3) to examine effects from each city’s PM2.5 on lung macrophage Tf, Fe, and antibacterial function.
Summary/Accomplishments (Outputs/Outcomes):The results indicated that daily PM2.5 samples in New York City (NYC), Los Angeles (LA), and Seattle had disparate metal compositions, with wide variations in absolute and relative Fe, Mn, Al, and V content, and significant differences in the relative ratios of each competitor to Fe. In vitro studies with NR8383 cells sought to characterize if each competitor (at levels that could be encountered in PM2.5) could alter cell Fe homeostasis and ultimately, which competitor was most potent. Using induced iron response protein (IRP) binding to iron response elements as an indicator of shift in cellular Fe balance, it was seen that if cells were treated with Fe3+ alone or with V, Al, or Mn (individually or in combinations) at levels equivalent to those expected in 500 μg of a PM2.5 sample, each competitor caused an Fe deficit. Using increasing molar ratios of competitor to Fe, a determination was made that V had the greatest effect on Fe status and Mn the least. In studies using combinations, the competitors showed that there was a synergistic effect when V and Mn were both present; co-presence of Al with Mn or V had little impact. To see if effects observed with varying ratios of Al, Mn, and V would reflect what might occur with actual PM2.5, cells were treated with Fe alone and with Al, Mn, and V. It was found that IRP activation (compared to that from Fe alone) was greatest in cells treated with the combination of Fe+V+Al+Mn that would be found in NYC. Effects from co-treatments using levels of the metals found in PM2.5 from Seattle or Los Angeles were minimal.
Because nitric oxide (NO) might affect IRP activation, iNOS levels were also assayed in the cells; analyses of ERK-1 and -2 activation were performed concurrently as these play a role in iNOS formation. Only increasing amounts of Al had significant effects on iNOS expression; treatment with increasing ratios of V and Mn failed to induce iNOS to levels significantly above that of Fe alone. This would suggest that observed effects of V on IRP activity were unadulterated (i.e., no significant increase in NO that could enhance IRP-1 binding activity). Results of the ERK studies indicated that increasing ratios of V and Al both caused significant increases in phosphorylation/activation of ERK-1 (p44), but only V increased ERK-2 (p42) activation. These results indicate that at least two PM-associated metals induce effects on cell Fe homeostasis regulatory mechanisms (i.e., the IRPs—in either a direct or indirect manner) even when there is a level of Fe present that should keep the cell Fe-sufficient. A re-examination of the three city IRP studies in the context of the inhibitor-to-Fe ratios present in their daily samples as well as the NO studies’ findings allowed us to ultimately conclude that it is the relative amount of V to Fe that is most critical in determining if a given PM2.5 sample is likely to modify the Fe status of a lung macrophage. Furthermore, in PM that contains moderate-to-high amounts of Al, while effects on cell Fe status are likely, use of the IRP marker as an indicator of this outcome is not practical due to confounding effects introduced by effects on NO formation induced by Al ions.
Performing the in vivo exposure studies outlined for Aim 3 was ultimately not possible due to the limitations in the total amount of any given day’s sample of PM2.5. Instead, the information expected to be gleaned from those studies was obtained, in part, from a concurrent NIH/NIGMS-funded study. Rats were exposed 5 hr/d for 5 d to atmospheres containing physico-chemically distinct forms of V (or other PM2.5 metals) and their lung fluids were then analyzed for total Fe content, ferritin and Tf levels. Antibacterial activity in the lungs of exposed cohorts, reflecting the functional status of local macrophages, was also examined. These studies indicated that prior to the start of a lung infection, exposure to pentavalent V—the most common form found in PM—caused significant increases in lavage fluid Fe and ferritin levels, but had less overall effect on total Tf levels. Effects from soluble V were greater than those from an insoluble counterpart. These same result patterns were seen in the ability of the exposed rats to clear a viable bacterial challenge from their lungs, i.e., rats that inhaled soluble V had the most significantly reduced resistance against a pathogen as compared to controls.
These rat study results, taken together with those of the in vitro studies performed here, suggest that soluble V ion-induced alterations in the ability of Tf to bind Fe can lead to increases in the levels of free Fe in the airways and concurrently, less Fe delivery to resident phagocytes. With both more Fe available for sustenance and local immune cells less capable of performing their normal sentinel duties, the survival of most common bacterial pathogens that invade the lungs would then be greatly enhanced. The specific mechanisms hypothesized and then validated in these studies now allow us to better explain the means by which PM2.5—and more importantly, its specific constituents—act to induce or exacerbate infectious lung diseases in exposed populations.
Conclusions:- Select metals within a given sample of PM2.5 can cause altered cellular Fe homeostasis.
- Effects of PM2.5 with respect to altered macrophage Fe homeostasis—from region to region, or site to site in a given region—are governed by the relative content relationships between Fe and at least three co-constituent metals, e.g., V, Mn, and Al. Of these three, V is the most potent effector on this parameter.
- Analysis of IRP activity can be an effective way to examine effects of a variety of criteria pollutants upon Fe homeostasis in the lungs. But, Investigators need to monitor for effects on NO formation by the pollutants to determine if their measured effects on IRP are being adulterated.
Technical Report:
Long Version of Final Report (PDF) (4 pp, 106 K, About PDF)
Journal Articles on this Report: 5 Displayed | Download in RIS Format
| Other subproject views: | All 5 publications | 5 publications in selected types | All 5 journal articles |
| Other center views: | All 95 publications | 86 publications in selected types | All 74 journal articles |
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Cohen MD. Pulmonary immunotoxicology of select metals: aluminum, arsenic, cadmium, chromium, copper, manganese, nickel, vanadium, and zinc. Journal of Immunotoxicology 2004;1(1):39-69. |
R827351 (2003) R827351 (Final) R827351C008 (2003) R827351C008 (Final) |
not available |
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Cohen MD, Prophete C, Sisco M, Chen LC, Zelikoff JT, Smee JJ, Holder AA, Crans DC. Pulmonary immunotoxic potentials of metals are governed by select physicochemical properties: chromium agents. Journal of Immunotoxicology 2006;3(2):69-81. |
R827351 (Final) R827351C008 (Final) |
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Cohen MD, Sisco M, Prophete C, Chen LC, Zelikoff JT, Ghio AJ, Stonehuerner JD, Smee JJ, Holder AA, Crans DC. Pulmonary immunotoxic potentials of metals are governed by select physicochemical properties: vanadium agents. Journal of Immunotoxicology 2007;4(1):49-60. |
R827351 (Final) R827351C008 (Final) |
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Ghio AJ, Cohen MD. Disruption of iron homeostasis as a mechanism of biologic effect by ambient air pollution particles. Inhalation Toxicology 2005;17(13):709-716. |
R827351 (Final) R827351C008 (Final) |
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Prophete C, Maciejczyk P, Salnikow K, Gould T, Larson T, Koenig J, Jaques P, Sioutas C, Lippmann M, Cohen M. Effects of select PM-associated metals on alveolar macrophage phosphorylated ERK1 and -2 and iNOS expression during ongoing alteration in iron homeostasis. Journal of Toxicology and Environmental Health, Part A 2006;69(10):935-951. |
R827351 (Final) R827351C008 (Final) R827351C010 (Final) R827352 (Final) R827352C014 (Final) R827355 (Final) R827355C008 (Final) |
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PM2.5, metals, immune, macrophage, iron, IRP,
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ENVIRONMENTAL MANAGEMENT, Air, Scientific Discipline, Health, RFA, PHYSICAL ASPECTS, Risk Assessment, Risk Assessments, Analytical Chemistry, Health Risk Assessment, Physical Processes, Atmospheric Sciences, particulate matter, Environmental Chemistry, Environmental Monitoring, exposure assessment, pulmonary phagocyte iron status, ambient air quality, chemical characteristics, epidemelogy, metal absorption, human health risk, lung injury, pneumonia, air toxics, particulates, Sulfur dioxide, toxicology, atmospheric particles, acute lung injury, air pollution, environmental risks, metals, ambient air monitoring, atmospheric particulate matter, leukocyte function, exposure, atmospheric aerosol particles, airborne particulate matter, human exposure, PM
Relevant Websites:
Long Version of Final Report (PDF) (4 pp, 106 K, About PDF)
http://www.med.nyu.edu/environmental/
http://es.epa.gov/ncer/science/pm/centers.html
Progress and Final Reports:
2000 Progress Report
2001 Progress Report
2002 Progress Report
2003 Progress Report
Original Abstract
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