ObjectiveTo investigate the changes of lung function after exposure to fine particulate matter (PM2.5) for 60 days and the expression of miR-146 in mice.MethodsThirty SPF BALB/c mice were treated with noninvasive tracheal instillation of fine particulate matter suspension at different doses (2.5 mg/kg, 5.0 mg/kg, 10.0 mg/kg) for 2 months (two times one week), the blank group and normal saline group were set as control groups. The mice were examined and killed on the next day after the last instillation. Histopathological changes of the lungs, pro-infammatory factors levels in the lung tissues, pulmonary functions and the relative expression of miR-146a and miR-146b in the lung tissues were detected.ResultsPeak inspiratory flow (PIF) and peak expiratory flow (PEF) were decreased significantly after PM2.5 exposure, however, lung resistance increased and maximal voluntary ventilation reduced from the general tendency without significant difference. Hematoxylin-eosin stain showed lymphocyte infiltration and macrophage infiltration by phagocytic particles, alveolar spacer widening, inflammatory response increased with the increase of PM2.5 exposure dosage. Pro-infammatory factors as interleukin-6 in the bronchoalveolar lavage fluid, interferon-γ and tumor necrosis factor-α in the lung homogenate were increased significantly by enzyme linked immunosorbent assay. The relative expressions of miR-146a and miR-146b were up-regulated remarkablely in treatment groups compared to the control group by real-time fluorescence quantitative polymerase chain reaction, which had negative relationships with PIF and PEF.ConclusionsThe lung function of mice decreases significantly after exposure to fine particulate matter, and the expression of miR-146 is up-regulated.
