2008 Progress Report: Animal models: Cardiovascular Disease, CNS Injury and Ultrafine Particle Biokinetics

EPA Grant Number: R832415C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R832415
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Rochester PM Center
Center Director: Oberdörster, Günter
Title: Animal models: Cardiovascular Disease, CNS Injury and Ultrafine Particle Biokinetics
Investigators: Oberdörster, Günter , Elder, Alison C.P. , Oakes, David , Couderc, Jean-Philippe , Phipps, Richard , Gelein, Robert , Kreyling, Wolfgang
Institution: University of Rochester , GSF-National Research Center for Environment and Health
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2012)
Project Period Covered by this Report: October 1, 2007 through September 30,2008
RFA: Particulate Matter Research Centers (2004) RFA Text |  Recipients Lists
Research Category: Human Health , Air

Objective:

The objective of the Core 4 studies is to correlate physico-chemical particle characteristics (from Core 1 measurements) with pulmonary and cardiovascular endpoints following exposure of animals to inhaled ambient concentrated ultrafine/fine particles, inhaled freshly generated exhaust particles from low and ultralow diesel fuel, and intratracheally administered ultrafine and fine ambient particles from different sites and sources. Effects measurements will take into account endpoints determined in the epidemiological (Core 2) and clinical (Core 3) studies and coordinate mechanistic evaluations with Core 5 in vitro studies. In addition, effects on the CNS will also be assessed.

Progress Summary:

Exposures of Rats to Freshly Generated On-Road Aerosols
Humans with type II diabetes have been shown in recent epidemiological studies to be susceptible to the adverse health effects related to ambient particulate matter exposures. There are several animal models of diabetes, of which one is the JCR:LA-cp rat. Although these rats are not hyperglycemic (according to published literature and our results), the JCR cp/cp rats are obese, hyperlipidemic, hyperinsulinemic, and have atherosclerotic and ischemic lesions that are hallmark features of human type II diabetes. Heterozygotes or homozygous 43 normals (designated by JCR +/?) are not obese or hyperinsulinemic and do not exhibit the atherosclerotic lesions that the cp/cp rats do. Females of the same strain are similar to the +/? rats, which is why males are used exclusively in our studies.
 
One of the hypotheses being investigated in our studies in coordination with the Cores 2 and 3 projects is that some of the adverse health effects associated with exposure to ambient particulate pollution are causally related to inhaled ultrafine particles (UFP) and their gaseous co-pollutants. We have recently completed two rounds of studies using the JCR rats, one in which they were exposed to freshly generated exhaust emissions aerosols (two fuel types) in a mobile laboratory and another where the rats were exposed to concentrated ambient ultrafine particle-containing aerosols using the HUCAPS system.
Due to the limitation on the total number of animals that could be exposed, we focused on genetic background and exhaust atmosphere as being the response modifiers. Exposures to low- and ultralow-sulfur Diesel fuel exhaust emission aerosols were conducted in compartmentalized whole-body chambers while the mobile laboratory was driven between Rochester and Utica (NY I-90). Rats exposed to ambient UFPs received either HUCAPS aerosols or filtered air. Endpoints related to lung inflammation, inflammatory cell activation, acute phase responses, and platelet activation were measured after exposure. As in the past, groups of rats were also implanted with radiotransmitters to continuously monitor changes in heart rate, blood pressure, temperature, and activity associated with exposure to exhaust emissions or clean, filtered air.
 
There was an obvious effect of obesity and insulin resistance on baseline lavage inflammatory parameters, namely that the JCR cp/cp (obese) rats had higher total cell numbers, percentages of PMNs, and lavage fluid protein content and LDH and β-glucuronidase activities than their lean litter mates. However, neither the emission nor the HUCAPS aerosols had any consistent effects on these parameters. We also measured several parameters in serum and lavage fluid related to inflammation and metabolism using a rat adipokine panel bead array. For most of the parameters, the obese cp/cp rats had higher levels than in the lean rats. Another observation was the there was a slight decrease in the number of circulating platelet microparticles in the obese rats that were exposed to either the 44 HUCAPS or exhaust emission aerosols. Finally, samples obtained from the concentrator study revealed that the JCR cp/cp rats are iron overloaded and that HUCAPS exposure exacerbates this. The specific implications of this iron overloaded state in JCR cp/cp rats in terms of responses to low-level ambient UFP exposure are not yet clear. A manuscript(s) reporting these findings are in preparation.
 
The evaluations of blood pressure, heart rate, and heart rate variability changes in the rats that were exposed to exhaust emission or HUCAPS aerosols are ongoing. We found a significant divergence in heart rate following on-road exposures between the air- and full exhaust-exposed rats that increased over time in the post-exposure period. More specifically, the heart rate continued to decline over time in the exhaust-exposed rats. The statistical analyses of these data are almost complete. 
 
Exposures of R6/2 Mice to Concentrated Ambient Ultrafine Particle-Containing Aerosols
Based on previous studies from our group demonstrating that inhaled poorly soluble laboratory-generated UFP travel to the brain (Oberdörster et al., 2002, 2004) and evidence that they cause oxidative stress and inflammation in those regions where particles accumulate (Elder et al., 2006), we hypothesized that ambient UFP can induce similar effects, particularly in an animal model that exhibits early-onset neurodegeneration (in this case Huntington’s disease, HD; Mangiarini et al., 1996). Transgenic R6/2 mice express 105-150 polyglutamine (polyQ) repeats in the huntingtin protein (Htt) and are the best characterized and most widely used of the HD animal models. Nuclear inclusions of aggregated Htt are abundant throughout the whole brain in these mice and can be detected as early as three weeks of age (8). The mice exhibit subtle motor deficits as early as one month of age, which then lead to overt symptoms by two months; death occurs within three to four months (Carter et al., 1999; Lione et al., 1999; Murphy et al., 2000).
 
HD and other neurodegenerative diseases have in common abnormal protein folding and aggregation (e.g., Alzheimer’s, Creutzfeldt-Jakob, Parkinson’s). However, the significance of protein aggregation in these diseases is not entirely clear, as there is debate regarding whether the aggregated proteins are toxic or the misfolded monomers. Nonetheless, recent acellular 45 assays have shown that particles of different sizes, shapes, and surface chemistries can induce the unfolding and subsequent fibrillation (aggregation) of proteins (Linse et al., 2007). We hypothesized that the UFP present in ambient aerosols could be translocated to the brain, potentiate the aggregation of Htt, and accelerate neurodegeneration in exposed R6/2 mice.
 
We exposed the R6/2 mice, starting at 5-7 days of age, to concentrated ambient UFP-containing (HUCAPS) aerosols for 4 hrs/day, 5 days/week, for a total of 6 weeks in whole-body exposure chambers. About 1 week after the mouse pups were weaned, they were trained on an apparatus that allows an evaluation of locomotor function (Rotarod) and then re-tested every week through the end of exposure (a total of 4 evaluation points). Statistical analyses revealed that, unlike non-transgenic mice, the Rotarod performance of the transgenic mice declined over time. For those mice exposed to HUCAPS aerosols, the performance was significantly lower by the third week of testing, whereas for filtered air-exposed mice, performance did not drop significantly until the fourth testing week. The mice were euthanized 24-48 hrs after the last exposure, with one group being used for evaluations of lung inflammatory responses and one used to collect tissue samples for histo-pathological analyses. Serial coronal sections of brain tissue will be evaluated for striatal atrophy and huntingtin protein (Htt) expression and aggregation. Other tissues have also been saved so that we can examine Htt aggregation as a result of exposure in other tissues (e.g., lung, heart, pancreas).
 
Another group of pups will be born soon and they will be exposed to HUCAPS aerosols or filtered air for 6 weeks and then recovered for 4 weeks. As with the study described above, locomotor function testing using the Rotarod system will be done. In addition, their performance during the recovery period in a beam-break apparatus will be evaluated to assess additional aspects of locomotor function, such as traveled distance and jumping. The mice will be euthanized at the end of the 4 week-recovery and the same endpoints evaluated in brain tissue, lavage fluid, and blood.

Future Activities:

As mentioned above, we will be focusing on tissue analyses from the R6/2 mice that were exposed to HUCAPS aerosols. In addition, we have another 10-week study to complete (6  weeks of exposure with 4 weeks of recovery). We have saved several tissues from this study and hope to share them with other investigators who may be able to measure endpoints that we ourselves cannot. We will also continue our analyses of the heart rate variability data from the telemetered JCR rats that were exposed to freshly-generated emission aerosols and concentrated ambient PM. Lastly, in the fall of 2009, we will carry out a fourth on-road exposure study using the mobile emissions laboratory. We will test the specific hypothesis that exhaust filter technology will affect cardiovascular, pulmonary and CNS responses in rats
with compromised cardiovascular systems.

Journal Articles:

No journal articles submitted with this report: View all 62 publications for this subproject

Supplemental Keywords:

RFA, Health, PHYSICAL ASPECTS, Scientific Discipline, Air, particulate matter, Toxicology, Health Risk Assessment, Risk Assessments, Physical Processes, atmospheric particulate matter, atmospheric particles, acute cardiovascular effects, airway disease, exposure, animal model, ambient particle health effects, atmospheric aerosol particles, ultrafine particulate matter, PM, inhalation toxicology, cardiovascular disease

Progress and Final Reports:

Original Abstract
  • 2006 Progress Report
  • 2007 Progress Report
  • 2009 Progress Report
  • 2010 Progress Report
  • 2011 Progress Report
  • Final Report

  • Main Center Abstract and Reports:

    R832415    Rochester PM Center

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R832415C001 Characterization and Source Apportionment
    R832415C002 Epidemiological Studies on Extra Pulmonary Effects of Fresh and Aged Urban Aerosols from Different Sources
    R832415C003 Human Clinical Studies of Concentrated Ambient Ultrafine and Fine Particles
    R832415C004 Animal models: Cardiovascular Disease, CNS Injury and Ultrafine Particle Biokinetics
    R832415C005 Ultrafine Particle Cell Interactions In Vitro: Molecular Mechanisms Leading To Altered Gene Expression in Relation to Particle Composition