The acute airway inflammation induced by PM2.5 exposure and the treatment of essential oils in Balb/c mice

PM2.5 is the main particulate air pollutant whose aerodynamic diameter is less than (2.5) micron. The inflammation of various respiratory diseases are associated with PM2.5 inhalation. Pro-inflammatory cytokine IL-1 beta generated from effected cells usually plays a crucial role in many kinds of lung inflammatory reactions. The exacerbation of Th immune responses are identified in some PM2.5 related diseases. To elucidate the underlying mechanism of PM2.5-induced acute lung inflammation, we exposed Balb/c mice to PM2.5 intratracheally and established a mice model. Acute lung inflammation and increased IL-1 beta expression was observed after PM2.5 instillation. Regulatory factors of IL-1 beta (TLR4/MyD88 signaling pathway and NLRP3 inflammasome) participated in this lung inflammatory response as well. Treatment with compound essential oils (CEOs) substantially attenuated PM2.5-induced acute lung inflammation. The decreased IL-1 beta and Th immune responses after CEOs treatment were significant. PM2.5 may increase the secretion of IL-1 beta through TLR4/MyD88 and NLRP3 pathway resulting in murine airway inflammation. CEOs could attenuate the lung inflammation by reducing IL-1 beta and Th immune responses in this model. This study describes a potentially important mechanism of PM2.5-induced acute lung inflammation and that may bring about novel therapies for the inflammatory diseases associated with PM2.5 inhalation.