Background: Pulmonary surfactant (PS) plays an important role in the treatment of sepsis-induced acute lung injury (ALI). Liraglutide, a glucagon-like peptide-1 (GLP-1) analog, improves the secretion and function of PS in ALI, but the underlying mechanism remains unknown. This study aimed to investigate how liraglutide regulates PS secretion in ALI.
Methods: C57BL/6 mice were injected subcutaneously with normal saline containing different concentrations of liraglutide after the establishment of the ALI model. MLE-12 cells were treated with liraglutide after LPS stimulation. The survival rate of mice, wet/dry weight ratio, inflammatory factors in bronchoalveolar lavage fluid (BALF), pulmonary injury, and apoptosis were analyzed. Cell viability, proliferation, apoptosis, the expression of SP-A, SP-B, and expression of autophagy-related proteins in cells were measured.
Results: ALI mice showed reduced pulmonary injury, less apoptosis, and less inflammation compared to the controls. Liraglutide prolonged survival, decreased the wet/dry weight ratio, reduced inflammatory responses, and attenuated pulmonary edema compared with the ALI group. Moreover, LPS-induced cell damage and reduction of SP-A and SP-B expression were markedly reversed by liraglutide in MLE-12 cells. Furthermore, the protective effects of liraglutide were reversed by rapamycin.
Conclusion: Liraglutide alleviate sepsis-induced ALI by inhibiting autophagy and regulating PS.
Keywords: Liraglutide; acute lung injury; autophagy; pulmonary surfactant; sepsis.