The effect and mechanism of Modified Guo-Min Decoction and Yu-Ping-Feng Powder on fine particulate matter-induced lung inflammatory injury and airway mucus hypersecretion in rats

Background Exposure to fine particulate matter (PM2.5) severely impairs public health. The mechanism of PM2.5-induced lung injury is complex and diverse. Modified Guo-Min Decoction (MGMD) and Yu-Ping-Feng Powder (YPFP) have been found to improve clinical symptoms in respiratory patients during smog weather, but the mechanism remains unclear. This study aimed to investigate the effect and mechanism of YPFP and MGMD against PM2.5-induced lung injury. Methods We established the PM2.5 animal model by intratracheal instilling of PM2.5 suspensions. Rats were administrated MGMD/YPFP/distilled water via gavage every day, and all rats were sacrificed after 28 days. At the end of experiment, BALF and lung tissues were collected. Condition of lung injury, inflammatory cells infiltration, inflammatory cytokines, MUC5AC synthesis and release, and phosphorylation of TLR2-MyD88-NFκB and EGFR-PI3K-AKT signalling pathway were evaluated. Results The results demonstrated that both MGMD and YPFP protected rats from PM2.5-induced damaged structure of lung tissues. The infiltration of neutrophil, monocyte, lymphocyte, and eosinophil was reduced after the treatment of two therapies. The production of pro-inflammatory mediators, MCP-1 and NE, as well as the type2 inflammation-related cytokines, IgE and IL-4, were decreased by MGMD and YPFP. However, the MGMD showed more potent effect on inhibiting IL-4, while YPFP benefited in preventing ICMA-1, IL-1β, and IL-17A. Rare significance was detected in the TLR2-MyD88-NFκB of each group. Treatment with MGMD and YPFP decreased goblet cell hyperplasia and the expressions of MUC5AC. The further investigation demonstrated that YPFP had the effect of simultaneously inhibiting the phosphorylation of PI3K and AKT, whereas MGMD only showed a significant difference in AKT. Conclusions Therefore, both MGMD and YPFP could significantly attenuate PM2.5-induced inflammation of lung and airway mucus hypersecretion. Nevertheless, YPFP had more advantage in preventing type1 inflammation and mucus hypersecretion, while MGMD was more beneficial in reducing type2 inflammation.