Abstract
The present study investigated effects of exposure to ZnO nanoparticles on pulmonary fibrosis in a mouse model treated with bleomycin (BLM). Female C57BL/6Jcl mice were divided into BLM and non-BLM groups. In each group, three doses (10, 20, 30 µg/mouse) of ZnO nanoparticles with primary diameter of 20 nm were delivered into the lungs through pharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) and the lungs were collected at 10 or 14 days after administration. Exposure to ZnO nanoparticles dose-dependently decreased the body weight and increased the lung weight.
At 10 days after administration, the counts of total cell, neutrophil and lymphocyte in BALF increased in both BLM and non-BLM groups. The levels of IL-1 beta and MCP-1 in BALF also increased in BLM groups, while no significant change was observed in non-BLM groups. Moreover, the levels of such inflammatory cytokines were much higher in BLM groups than those in non-BLM groups. With regard to pathological changes, in contrast to the recovered inflammatory infiltration in non-BLM groups, collagen deposition was observed in BLM groups exposed to 20 µg ZnO nanoparticles at 14 days post administration.
This study showed that exposure to ZnO nanoparticles induced pulmonary inflammation to a larger extent in the BLM-treated mice than the BLM-non-treated mice. The study suggests that BLM-treated mice give a sensitive model for investigation on the profibrotic effects of pulmonary exposure to engineered nanomaterials.
