2002 Progress Report: Mechanisms of Toxicity of Particulate Matter Using Transgenic Mouse Strains

EPA Grant Number: R827355C005
Subproject: this is subproject number 005 , established and managed by the Center Director under grant R827355
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Airborne PM - Northwest Research Center for Particulate Air Pollution and Health
Center Director: Koenig, Jane Q.
Title: Mechanisms of Toxicity of Particulate Matter Using Transgenic Mouse Strains
Investigators: Luchtel, Daniel L. , Feigl, Eric , Kavanagh, Terrance J , Rosenfeld, Michael
Current Investigators: Luchtel, Daniel L. , Baker, Coralie , Ceballos, Diana , Kavanagh, Terrance J , Leaman, Susan , McConnachie, Lisa , Rosenfeld, Michael
Institution: University of Washington
EPA Project Officer: Chung, Serena
Project Period: June 1, 1999 through May 30, 2004 (Extended to May 31, 2006)
Project Period Covered by this Report: June 1, 2002 through May 30, 2003
Project Amount: Refer to main center abstract for funding details.
RFA: Airborne Particulate Matter (PM) Centers (1999) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air

Objective:

The objective of this research project is to determine whether particulate matter (PM) deposited in the lungs causes the release of inflammatory cytokines from the lungs that target the cardiovascular system. Transgenic mouse strains with specific cardiovascular genetic alterations are used to address the research needed to identify potential health conditions that enhance susceptibility to adverse PM health effects. The nature of such health conditions provides insight into the biological mechanisms by which PM mediates acute and chronic health effects.

Progress Summary:

During the past year, an extensive statistical analysis was completed of three studies conducted by this project. This involved the development of a new statistical approach by Thomas Lumley. The basis of this analysis is as follows. A standard ANOVA analysis of the collected cardiovascular telemetry data obtains all its statistical information about variability from comparisons between mice; however, it is inefficient when there is mouse-to-mouse variability in the response. By analyzing the time series of measurements for each mouse, it is possible to compute a mouse-specific estimate of uncertainty and so to make mouse-specific inferences about the effects of PM exposure and oro-pharyngeal aspiration. These inferences can be combined across mice using a random-effects meta-analysis. This two-stage analysis strategy is similar to that used in the National Morbidity, Mortality, and Air Pollution Study epidemiological studies of PM, where city-specific time series models were fitted and then combined across cities, although the details of the analyses differ.

Figure 1. Washington, DC and St. Louis, MO PM

Two groups of animals were compared: (1) control normal C57/BL6 male mice; and (2) transgenic ApoE knockout male mice. The PM sources used were urban air PM Standard Reference Materials (SRM) from Washington, DC (#1649) and St. Louis, MO (#1648). The method of exposure was oro-pharyngeal instillation of the PM.

Telemetric monitoring of cardiovascular function was conducted in freely moving, nontethered mice. The monitoring was conducted via an implanted radio transmitter. A catheter attached to the transmitter was inserted into the left carotid artery, while a transmitter was positioned between the skin and body wall. After surgery, the animals were allowed to recover for 1 week to 10 days. A 1-day baseline recording was followed by a vehicle exposure (pyrogen-free saline, 50 µL/mouse) and 3-day recording. After recovery for 1-2 weeks, a second baseline was recorded, and mice then were exposed to a dose of 125 µg PM/50 µL saline/mouse followed by a second 3-day recording of cardiovascular parameters. Three studies were analyzed, including one with a cross-over design to randomize vehicle versus dust exposure. In summary, the following was found: (1) there was a statistically significant reduction in heart rate with the Washington, DC dust, but not with the St. Louis dust; this reduction was found at lag times of 4 to 7 hours, 1 day, and 2 days; (2) no statistically significant changes in blood pressure were found at any time period; and (3) the cross-over design allowed an estimate of the effects of the background experience, and: these effects were not statistically significant. There was no statistical difference between the genotypes in their response to PM. We believe this was probably due to the fact that relatively young animals (mice aged 3-4 months) were studied. Recently, histological analyses by Michael Rosenfeld show that significant atherosclerotic lesions do not develop in the ApoE-/- model until 10-12 months of age. Older animals are being used in ongoing studies.

Another radio telemetry study measuring electrocardiogram (ECG) and heart rate also was conducted this past year. Again, individual mice were exposed to 125 µg of SRM #1648 (St. Louis urban dust) in 50 µL saline by oro-pharyngeal aspiration. Recordings were collected using the protocol described above. Time-domain measures were calculated from the ECGs; that is, the standard deviation (SD) of all normal R-R intervals (SDNN) and the square root of mean of squared differences between adjacent normal R-R intervals (MSSD). Both measures showed an increase during the 3 days following the saline exposure, and the 3 days following the dust exposure (SDNN result shown in graph). Similar results were shown in a cross-over design exposure. Notable differences were not found in the responses of normal C57/BL6 versus ApoE-/- animals.

Figure 2. SDNN ApoE

Future Activities:

The future activities of this research project will be to:

(1) Study the toxicity of Seattle, WA PM collected on filters and comparison with effects of east coast PM obtained from Bob Devlin at EPA.

(2) Study the effect of age combined with an additional risk factor, Chlamydia infection, in animals exposed to PM.

(3) Assist Joel Kaufman with development of the diesel exhaust facility, and conduct inhalation exposures of mice to diesel exhaust particles in parallel with human exposures.

(4) Study lavage cells after Seattle, WA PM exposure by flow cytometry to identify the cell types; we also will analyze lavage fluid and blood for cytokine profiles.

(5) Conduct genetic analyses using microarrays before and after exposure to Seattle, WA PM.

In addition, a pilot grant application with Terry Kavanagh was submitted that, if funded, would allow us to study the effects of PM in an oxidant transgenic mouse model. The rationale for the proposed study is that glutathione (GSH) is a major antioxidant in the lung, and inhibition of its synthesis has been shown to exacerbate lung injury by a large number of toxicants. We propose to test the hypothesis that mice having a genetic deficiency in GSH synthesis will show increased susceptibility to PM. These data will provide insight regarding the role of GSH and Glutamate-cysteine ligase (GCL) in defense against PM-induced cardiopulmonary injury.

Journal Articles:

No journal articles submitted with this report: View all 8 publications for this subproject

Supplemental Keywords:

air pollution, air pollutants, particulate matter, PM, fine particulates, PM2.5, statistical analyses, toxicity of PM, mechanisms of toxicity, transgenic mouse strains, inflammatory cytokines, cardiovascular system, cardiovascular function, cardiovascular genetic alterations, heath effects, acute health effects, chronic health effects, cardiovascular disease, cardiovascular telemetry, urban dust, urban air PM, exposure, radio telemetry, atherosclerotic lesions, blood pressure, electrocardiogram, heart rate, genetic analyses, human exposures, cytokine profiles, diesel exhaust particles, St. Louis, Missouri, MO, Seattle, Washington, WA, Washington, DC., Health, Scientific Discipline, Air, particulate matter, Toxicology, air toxics, Environmental Chemistry, Health Risk Assessment, Epidemiology, Risk Assessments, Biochemistry, Atmospheric Sciences, health effects, ambient aerosol, particulates, ambient air quality, air pollutants, morbidity, cardiopulmonary responses, human health effects, exposure and effects, animal model, hazardous air pollutants, exposure, air pollution, particle exposure, human exposure, atmospheric aerosols, ambient particle health effects, mortality studies, inhalation, mortality, particle transport, cardiovascular disease, human health risk, aerosols, atmospheric chemistry

Relevant Websites:

http://depts.washington.edu/pmcenter/ Exit

Progress and Final Reports:

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

  • Main Center Abstract and Reports:

    R827355    Airborne PM - Northwest Research Center for Particulate Air Pollution and Health

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827355C001 Epidemiologic Study of Particulate Matter and Cardiopulmonary Mortality
    R827355C002 Health Effects
    R827355C003 Personal PM Exposure Assessment
    R827355C004 Characterization of Fine Particulate Matter
    R827355C005 Mechanisms of Toxicity of Particulate Matter Using Transgenic Mouse Strains
    R827355C006 Toxicology Project -- Controlled Exposure Facility
    R827355C007 Health Effects Research Core
    R827355C008 Exposure Core
    R827355C009 Statistics and Data Core
    R827355C010 Biomarker Core
    R827355C011 Oxidation Stress Makers