Project description:In the present study, we investigate pulmonary transcriptional responses in mice following exposure in situ to ambient air in a heavily polluted urban environment. Mature C57BL/CBA male mice were caged in sheds located in an urban area near two working steel mills and a major highway in Hamilton, Ontario, Canada. Control mice were housed in the same environment but received only high-efficiency particle-filtered air. Whole lung tissues were collected from mice exposed for 3 weeks, 10 weeks or for 10 weeks followed by 6 weeks in the laboratory (16 weeks total). DNA microarrays were used to explore changes in pulmonary gene expression in mice breathing ambient air versus HEPA-filtered air. Transcriptional profiling revealed changes in the expression of genes implicated in the lipid droplet synthesis pathway (plin, dgat2, lpl, s3-12, agpat2), antioxidants (ucp1). We postulate that exposure to particulate matter adsorbed with polycyclic aromatic hydrocarbons triggers lipid droplet synthesis (holding depots for lipids and malformed/excess proteins tagged for degradation) in the lungs, which act to sequester particulates adsorbed with toxic chemicals. Increased lipid droplet synthesis could potentially lead to endogenous/stressor-induced synthesis of reactive oxygen species and activation of antioxidant mechanisms. Further investigation into the stimulation of lipid droplet synthesis in the lung in response to air pollution is warranted in order to better understand these mechanistic changes and the resulting health implications. Mature male C57BL/6 x CBA F1 hybrid mice were exposed to either HEPA-filtered or ambient air in Hamilton, ON, Canada. Animals were exposed starting May 14, 2004 for 3 weeks (3wk), 10 weeks (10wk), or for 10 weeks followed by 6 weeks of recovery (16wk). Each treatment group consisted of five mice, for a total of 30 mice. Total RNA was isolated from a random section of the whole lung using TRIzol reagent (Invitrogen) and purified using the RNeasy Mini Kit (Qiagen). RNA quality was confirmed by UV spectrophotometry and using an Agilent Bioanalyzer. Total RNA (200 ng) from HEPA-filtered air or whole air-exposed mice and Universal Mouse Reference RNA (Stratagene) were used to synthesize double-stranded cDNA and cyanine-labelled cRNA according to the manufacturer's instructions (Agilent Linear Amplification Kits, Agilent Technologies). Biological samples were labelled with Cy5 dye while the commercially available Stratagene mouse reference RNA was labelled with Cy3 dye. At each of the three time points, ambient air-exposed samples and HEPA-filtered samples were hybridized to Agilent microarrays. Arrays were washed, and scanned on an Agilent G2505B scanner. Data were acquired using the Agilent Feature Extraction software version 9.5.3.1.

Project description:The objective of this study was to compare the biological and toxicological response of apolipoprotein E-deficient (Apoe-/-) mice to 3R4F mainstream smoke exposure for 2 months in whole-body exposure chambers (WBEC) and nose-only exposure chambers (NOEC). Female ApoE-/- mice were randomized into four groups: two Sham groups, exposed to filtered air, and two 3R4F groups, exposed to CS from the 3R4F reference cigarette (550 Âµg TPM/L). Half the number of mice in the Sham- and CS-exposed groups were exposed in WBECs and the other half in NOECs. The exposure phase lasted 9 weeks and included 1 week of adaption, during which exposure in both chamber types was escalated in dose and duration to a maximum of 4 h per day. The TPM concentration and exposure duration in WBECs were matched to those in NOECs on the basis of the regimen that the mice tolerated, as determined by in-life findings on acute signs of nicotine toxicity. Fresh air breaks were introduced during the exposure period to maintain carboxyhemoglobin (COHb) concentrations at acceptable levels. More frequent and longer fresh air breaks were required for exposure in the WBEC than in the NOEC because of the greater internal volumeâ€”and, consequently, the longer durationâ€”required to clear smoke from the WBEC than from the NOEC. For animals in NOECs, a 30-min fresh air break was introduced after 2 and 3 h of exposure. For animals in WBECs, a 30-min fresh air break was introduced after 1 and 2 h of exposure and a 60-min fresh air break after the third hour of exposure. The general condition and health of the mice following exposure were monitored throughout the study. Full necropsy was performed 16-20 h after the last exposure without prior fasting, in accordance with previously described methods (Vanscheeuwijck et al., 2002). Differences between WBEC and NOEC expsoure were analyzed with regard to aerosol uptake, disease endpoints (adaptive changes in nasal epithelia, changes in lung function and inflammatory parameters, plasma cholesterol/triglyceride levels in lipoprotein fractions, and atherosclerosis plaque development), and systems biology endpoints (changes in the lung proteome and liver, nasal epithelial, and heart transcriptomes). All procedures involving animals were performed in a facility accredited by the Association for Assessment and Accreditation of Laboratory Animal Care International and licensed by the Agri-Food & Veterinary Authority of Singapore, with approval from an Institutional Animal Care and Use Committee and in compliance with the National Advisory Committee for Laboratory Animal Research Guidelines on the Care and Use of Animals for Scientific Purposes (NACLAR, 2004). Here, the protein expression data for lung tissue assessed by iTRAQ®-based quantitative proteomics will be described.

Dataset Information

Homo sapiens

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure