Sophoridine inhibits endotoxin-induced acute lung injury by enhancing autophagy of macrophage and reducing inflammation.

Acute lung injury (ALI) is characterized by uncontrolled inflammation, which can lead to respiratory distress syndrome and cause patient death. In this study, we sought to determine the role of sophoridine, a compound purified from sophora, in ALI. A mouse model of ALI was established by treating mice with LPS through nonexposed tracheal instillation. After LPS-induced mice were treated with sophoridine, LPS-induced alveolar wall thickening, alveolar interstitial inflammatory exudation and thickening, and the degree of pulmonary edema were found to be inhibited. Macrophages play an important role in inflammation, and in vitro experiments have demonstrated that sophoridine reduces the LPS-induced expression of inflammatory factors by macrophages, suggesting that sophoridine may inhibit lung inflammation in LPS-treated mice through reduces the secretion of inflammatory factors. Further, treatment with sophoridine up-regulated autophagy in macrophage cells in vitro and mouse lung tissues in vivo. LPS can bind to TLRs and activate the MyD88/NF-κB pathways, leading to increased inflammation in the pathogenesis of ALI. Our findings revealed that sophoridine down-regulated the expression of TLR4/MyD88/NF-κB and mTOR mRNA and protein in mouse pulmonary tissue. Collectively, these findings indicate that sophoridine may inhibit LPS-induced ALI by enhancing autophagy of macrophages and reducing inflammation.