The airway inflammation induced by nasal inoculation of PM2.5 and the treatment of bacterial lysates in rats.

Particulate matter (PM) is one of the most important environmental issues in China. This study aimed to explore the correlation between PM2.5 and airway inflammation in healthy rats. The PM2.5 group was given an intranasal instillation of PM2.5 suspension on 15 consecutive days, and each received oral saline from day 16 to 90. The BV intervention group was treated as the PM2.5 exposure group, except that BV instead of saline was given daily. A histopathologic examination was performed to evaluate the airway inflammation. The prevalence and function of Th1/Th2/Treg/Th17 cells were detected by flow cytometry and ELISA. The expression of AhR was detected by western blot and real-time PCR. We found that epithelial damage and increased infiltration of inflammatory cell were present in the airways after PM2.5 exposure; there was an immune imbalance of Th cells in the PM2.5 group; the expression of AhR was increased in the airways after PM2.5 exposure. In the PM2.5 + BV group, we demonstrated alleviated immune imbalance and reduced inflammatory cell infiltration in the airways. Our study showed that exposure to PM2.5 induced airway inflammation. The imbalance of Th1/Th2/Treg/Th17 in PM2.5-induced airway inflammation might be associated with activation of the AhR pathway. Oral BV reduces PM2.5-induced airway inflammation and regulates systemic immune responses in rats.