Efeitos da exposição aguda ao material particulado proveniente da queima de combustível diesel e biodiesel dos ônibus da cidade do Rio de Janeiro em pulmão de camundongos

Abstract

One of the main forms of air pollution in urban centers of Brazil comes from diesel combustion from bus and truck engines. Diesel in Brazil is composed of diesel fuel and biodiesel (BS) with the aim of reducing air pollution. Thus, our aim was to investigate the effect of BS particulate matter exposure from fuel burning by public transport of Rio de Janeiro City in mice lung. BS particulate matter was collected from the exhaust pipes of buses from the public transportation fleet of Rio de Janeiro City and dissolved in saline/dimethyl sulfoxide. Female C57BL/6 mice were treated with 250 μg or 1000 μg of BS particulate matter and the control group with vehicle by intranasal instillation along five consecutive days. After sixth day, 10 animals per group were euthanized and the lungs and broncoalveolar lavage were collected. Ten animals were separated only for pulmonary mechanic analysis. We demonstrated that BS particulate matter was able to penetrate into the lung in the BS 250 μg and BS 1000 μg groups. In addition, the agglomerate of BS particulate matter in pulmonary parenchyma was higher in the BS 250 μg and BS 1000 μg groups than in the control group. The instillation of BS particulate matter increased the static elastance (Est) and lung resistive pressure (ΔP1) in BS 250 μg and BS 1000 μg groups when compared to control group. Furthermore, the macrophage number and protein levels of tumor necrosis factor-α (TNF-α) were also increased in lung of the BS 250 and 1000 μg group when compared to control group. The BS particulate matter enhanced reactive oxygen species synthesis and the malondialdehyde levels in both treated groups when compared to control group. The expression of glutamate cysteine ligase modifier subunit was lower in the BS 250 μg group than in the control group. The protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2), nuclear factor kappa B (NF-κB) and heme oxygenase-1 (HO-1) enzyme was higher in BS 250 μg group, but lower in BS 1000 μg group, than in control group. In conclusion, the BS particulate matter instillation promotes inflammatory response and oxidative damage in mice lung activating Nrf2/HO-1 and NF-κB/TNF-α pathways.