Oxidative Stress Response of PM2.5 and Mixed Toxic Gases to Rat Trachea and Lung Tissue
Abstract Background:We performed this study to explore the inflammation and oxidative stress responses of rat trachea and lung caused by PM2.5 and mixed toxic gas.Materials and methods:Eighty-four Wistar rats were randomly assigned to receive exposure to PM2.5 and toxic gases containing carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2) or saline. Microflora in rat respiratory tract were investigated through testing secretion taken from posterior pharyngeal wall on Day 1, 7 and 30. Trachea and lung tissues were processed for scanning electron microscopic (SEM) and transmission electron microscopic (TEM) examinations. Cytokines in rat bronchoalveolar lavage fluid (BALF), serum and lung tissues were analyzed via enzyme-linked immunosorbent assay and real-time quantitative PCR.Results:Eight aerobes and seven anaerobes were firstly detected after exposure (p<0.01, respectively). Most of them are the pathogenic bacteria or opportunistic pathogen. SEM and TEM observations suggested that both normal structure of trachea and lung tissue were injured after exposure to PM2.5 with mixed toxic gas and the injure degree was concentration- and time-dependent. Interleukin 4 (IL-4), interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) expression in the BALF and lung tissue markedly increased on Day 1 and 7 (p<0.01, respectively). Interferon γ (IFN-γ) did not show significant change after exposure. On Day 30, all the detected cytokines decreased and even disappeared. All detected cytokines in the serum had no significant difference before and after exposure (p>0.05, respectively).Conclusion:PM2.5 with mixed toxic gas can lead to dysbacteriosis in respiratory tract and destroy the normal structure of trachea and lung tissue. The injure degree was concentration- and time-dependent. Local inflammatory response instead of systemic reaction may be predominant in the response of rat respiratory tract to PM2.5 with mixed toxic gas.