2003 Progress Report: Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron StatusEPA Grant Number: R827351C008
Subproject: 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: N/A
Title: Immunomodulation by PM: Role of Metal Composition and Pulmonary Phagocyte Iron Status
Investigators: Cohen, Mitchell
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
Particulate matter (PM) of less than 2.5 µm in diameter (PM2.5) has been shown in epidemiological analyses to induce/exacerbate infectious lung disease and, in toxicological studies, to alter the manner by which the lung responds to bacteria. This research has sought to validate the following hypotheses: (1) PM2.5 modulates lung phagocyte antibacterial function by altering cellular iron (Fe) status; (2) metals (as opposed to organics, biomatter, etc.) in PM2.5 underlie any change in lung leukocyte Fe status; and (3) relative Fe content in PM2.5 governs these effects. With respect to the latter, in PM2.5 with a high relative Fe content, uptake/slow dissolution of PM2.5-associated insoluble Fe and an increase in cellular deposition of soluble Fe (caused by transferrin [Tf] activity) will lead to Fe overload and decreased antibacterial function. Conversely, with low relative Fe content-PM2.5, a presence of relatively greater levels of competitors for Tf binding (e.g., aluminum [Al], manganese [Mn], and vanadium [V]) will cause an Fe deficit and reduced antibacterial function caused by the inhibited transport of endogenous Fe to the phagocytes.
To test these hypotheses, the objectives of this project are to: (1) collect daily PM2.5 samples, in cooperation with the Los Angeles and Seattle PM Centers, in the three metropolitan regions (New York City, Los Angeles, and Seattle) over a 3-month period to characterize any distinct patterns of proportionality of Fe to Al, Mn, and V; (2) determine in vitro if a presence of Al, Mn, and V impact Fe homeostasis in a rat lung macrophage cell line (i.e., NR8383) when varying doses of each metal (reflective of their relative amounts within each city’s PM2.5) are utilized; (3) use NR8383 cells treated with intact PM2.5 to prove that the metals in PM alone are responsible for any effects on Fe homeostasis; (4) use the in vitro results to extrapolate a minimal effective PM2.5 dose; and (5) instill rats with regional PM2.5 and examine effects from each city’s PM2.5 on lung Tf status, Fe status, and antibacterial function of lung macrophages recovered from these rats.
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 R827351C007, and R827351C009 through R827351C016).
Progress Year 2 of Project (Year 5 of NYU PM Center)
Daily regional PM2.5 samples in New York City, Los Angeles, and Seattle were collected and analyzed by x-ray fluorescent spectroscopy to determine general elemental composition and, specifically, the relative and absolute Fe, Al, Mn, and V contents. Results indicated that the PM in each city had disparate metal compositions; with wide variations in absolute and relative Fe, Mn, Al, and V; there were significant differences in the relative ratios of each of the metal competitors to Fe. Based on these differences, in vitro studies with NR8383 cells sought to characterize whether each competitor (at levels that would be encountered in a given day’s PM2.5) could alter cell Fe homeostasis and, ultimately, which competitor was most important for inducing the effect.
Our initial studies using induction of iron response protein (IRP) IRE sequence-binding activity as an indicator of shift in cellular iron balance indicated that if cells were treated with Fe (as Fe 3+) alone or with V, Al, or Mn (individually or in combinations) at levels equivalent to those expected in 500 µg of a given PM2.5 sample, each competitor caused Fe deficit in the cells. By employing increasing molar ratios of competitor to Fe, the determination was made that V had the greatest effect on Fe status and Mn the least. Studies using combinations of two or all three competitors indicated 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 determine if the effects observed with the varying molar ratios of Al, Mn, and V would reflect what might be occurring with actual PM that was present in the three cities, IRP studies were performed using cells treated with Fe alone and with Al, Mn, and V at levels that would be present in a 500 µg sample of a given day’s PM2.5. Using treatments that were based upon the PM of three randomly selected days in each city, it was found that levels of IRP activation (compared to that obtained with Fe alone) were greatest in cells treated with the combination of Fe + V + Al + Mn that would be found in New York City. Effects from the co-treatments using levels of the four metals found in the PM from Seattle or Los Angeles were minimal.
Because of the possibility that the presence of nitric oxide (NO) might affect the levels of IRP activation assayed in the above analyses, studies were undertaken to assess the induction of inducible nitric oxide synthase (iNOS) in these cultures. Analyses of the activation of ERK-1 and ERK-2 in the cells were performed concurrently because these MAP kinases are believed to play a role in the increased formation of iNOS. The results indicated that only increasing amounts of Al had any significant effect on iNOS expression; treatments with the increasing molar ratios of V and Mn used in the IRP studies failed to induce iNOS to levels significantly above that of the Fe alone and well below that of the iron chelator desferroxamine. This would suggest that the observed effects from V on IRP activity were unadulterated in that there was no significant increase in levels of NO that could enhance the binding activity of IRP-1. The results of the ERK activation studies indicated that the increasing molar ratios of V and Al both caused significant increases in the phosphorylation (and, hence, activation) of ERK-1 (p44); only V appeared to increase ERK-2 (p42) activation. For now, the results clearly indicate that at least two of these 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.
In light of these results, a re-examination of the three city IRP studies indicated that the selected days for Los Angeles had relatively high Al:Fe molar ratios (i.e., > 3.0). As these values fell into the range predicted to cause significant iNOS induction in the NR8383 cells, it is possible that any expected IRP activation was masked by an increased formation of NO. In contrast, the New York City samples had molar ratios of Al:Fe, Mn:Fe, and V:Fe that routinely fell into the previously determined optimal ranges (e.g., 0.75-1.50, 0.04-0.08, and 0.1-0.2, respectively) for inducing enhanced IRP activity in these cells. The samples from Seattle tended to have fairly low V:Fe molar ratios even while having values for Al:Fe and Mn:Fe that were expected to induce IRP activation. From these results, and the previous observations on IRP activation using varying molar ratios of these competitors for Tf binding, we conclude that it is the relative amounts of V to that of Fe that are most critical in determining whether a given PM sample is likely to modify the Fe status of a lung macrophage. Furthermore, in PM that contains moderate-to-high amounts of Al, although effects on Fe status are likely, use of the IRP marker as an indicator of this outcome is not practical because of the confounding effects introduced by effects on NO formation induced by the Al ions.
Studies to better discern the meaning of the three sets of observations of this project (i.e., changes in IRP activity, iNOS expression, and ERK-1/2 activation) are in progress.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
|Other subproject views:||All 5 publications||5 publications in selected types||All 5 journal articles|
|Other center views:||All 112 publications||101 publications in selected types||All 89 journal articles|
||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.||
Supplemental Keywords:thoracic particles, PM10, fine particles, PM2.5, ultrafine particles, PM0.1, 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, Analytical Chemistry, Environmental Monitoring, Physical Processes, Atmospheric Sciences, Risk Assessment, ambient air quality, atmospheric particulate matter, particulates, lung injury, metal absorption, air toxics, atmospheric particles, chemical characteristics, toxicology, ambient air monitoring, acute lung injury, airborne particulate matter, environmental risks, exposure, epidemelogy, Sulfur dioxide, air pollution, pneumonia, leukocyte function, aerosol composition, atmospheric aerosol particles, human exposure, PM, exposure assessment, human health risk, metals
Progress and Final Reports: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