Cardiac and pulmonary response of mice to pollution

Nag, Ria
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Background: Epidemiological studies have identified air pollution as a contributing factor in both pulmonary and cardiovascular disease, but the mechanisms whereby air pollution accelerates these diseases are not fully known. One common component of air pollution is the particulate fraction of diesel engine exhaust, generated from a variety of transportation and industrial sources. High levels of exposure to diesel exhaust are also an important occupational hazard for workers in transportation and industry. Methodology: As a model of exposure to this key component of air pollution, a suspension of standardized diesel engine particulate (DEP) was instilled into the trachea of anesthetized mice. All mice were subjected to a single dose of 100 µg of DEP. 24 h and 5 days after treatment, the mice were euthanized. Then their heart and lungs were rapidly collected and frozen, as were tissues from control animals, treated with PBS. RNA was extracted and pooled from quadruplicate samples, and analyzed by hybridization to highly representative microarrays containing the Operon V3® set of murine long oligonucleotides. Transcripts that appeared to be highly dysregulated in dye-reversed microarray experiments (with an absolute value of fold-change> 2) were tabulated and considered for confirmation by real-time PCR of RNA from individual animals. In addition heart tissues were evaluated by immunohistochemical methods for protein expression patterns. Because hypercholesterolemia is a known accelerating factor in the progression of atherosclerosis, simultaneous exposures of Apo E (-/-) mice to DEP were included, allowing an assessment of the combined effect of pollution and hypercholesterolemia. Results: 24 h after DEP exposure, 110 cardiac transcripts were dysregulated ( > 2 fold) in anyone experiment. 24 transcripts were observed to be dysregulated i.e., either up or down regulated, by greater than 2 fold in lung after both 24 hours and 5 days after DEP exposure. Cardiac expression of Vldlr, Txnip, Ftl 1, Echl, and Cpe (Very low density lipoprotein receptor, Thioredoxin interacting protein, Ferritin light chain 1, Delta3,5-delta2,4-dienoyl-coa isomerase, Carboxypeptidase E) were each found to be differentially dysregulated in Apo E(-/-) strain vs. wild type at 24 h; increased pulmonary expression of Saa3 (serum amyloid A3) was observed in lung. The change in abundance of each of these transcripts was confirmed by semi-quantitative Real Time PCR. Conclusion: Up-regulation of Cpe( carboxypeptidase E, a pro-hormone and neuropeptide processor) expression was observed in Apo E-/-mice heart by microarray, real time PCR and immunohistochemistry experiments. Differential up-regulation of Vldlr, Txnip, Ftl 1, Echl and Saa3 was observed in Apo E-/- mice in the heart and lung respectively, by microarray and real time PCR. Thus the study predicts some key genes (including those related to cardiovascular disease, inflammation, immune response and progression of atherosclerosis) that can be involved in the pathology of cardiac and pulmonary disorders due to acute exposure of DEP under hypercholesterolemia conditions.
Thesis (M.S.)--University of Hawaii at Manoa, 2008.
Includes bibliographical references (leaves 49-60).
60 leaves, bound 29 cm
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Theses for the degree of Master of Science (University of Hawaii at Manoa). Molecular Biosciences and Bioengineering; no. 4325
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