Protective Role of Liriodendrin in Sepsis-Induced Acute Lung Injury

In current study, we investigated the role of liriodendrin, a constituent isolated from Sargentodoxa cuneata (Oliv.) Rehd. Et Wils (Sargentodoxaceae), in cecal ligation and puncture (CLP)-induced acute lung inflammatory response and injury (ALI). The inflammatory mediator levels in bronchoalveolar lavage fluid (BALF) were determined by enzyme-linked immunosorbent assay (ELISA). Pathologic changes in lung tissues were evaluated via pathological section with hematoxylin and eosin (H&E) staining. To investigate the mechanism whereby liriodendrin regulates lung inflammation, the phosphorylation of the NF-kB (p65) and expression of vascular endothelial growth factor (VEGF) were determined by western blot assay. We show that liriodendrin treatment significantly improved the survival rate of mice with CLP-induced sepsis. Pulmonary histopathologic changes, alveolar hemorrhage, and neutrophil infiltration were markedly decreased by liriodendrin. In addition, liriodendrin decreased the production of the proinflammatory mediators including (TNF-α, IL-1β, MCP-1, and IL-6) in lung tissues. Vascular permeability and lung myeloperoxidase (MPO) accumulation in the liriodendrin-treated mice were substantially reduced. Moreover, liriodendrin treatment significantly suppressed the expression of VEGF and activation of NF-kB in the lung. We further show that liriodendrin significantly reduced the production of proinflammatory mediators and downregulated NF-kB signaling in LPS-stimulated RAW 264.7 macrophage cells. Moreover, liriodendrin prevented the generation of reactive oxygen species (ROS) by upregulating the expression of SIRT1 in RAW 264.7 cells. These findings provide a novel theoretical basis for the possible application of liriodendrin in clinic.