Schisantherin A protects lipopolysaccharide-induced acute respiratory distress syndrome in mice through inhibiting NF-κB and MAPKs signaling pathways

Acute respiratory distress syndrome (ARDS) is characterized by polymorphonuclear neutrophils (PMNs) adhesion, activation, sequestration and inflammatory damage to alveolar-capillary membrane. Schisantherin A, a dibenzocyclooctadiene lignan isolated from the fruit of Schisandra sphenanthera, has been reported to have anti-inflammatory properties. In the present study, we aimed to investigate the protective effects of schisantherin A on LPS-induced mouse ARDS. The pulmonary injury severity was evaluated 7 h after LPS administration and the protective effects of schisantherin A on LPS-induced mouse ARDS were assayed by enzyme-linked immunosorbent assay and Western blot. The results revealed that the wet/dry weight ratio, myeloperoxidase activity, and the number of total cells, neutrophils and macrophages in the bronchoalveolar lavage fluid (BALF) were significantly reduced by schisantherin A in a dose-dependent manner. Meanwhile, pretreatment with schisantherin A markedly ameliorated LPS-induced histopathologic changes and decreased the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in the BALF. In addition, the phosphorylation of nuclear transcription factor-kappaB (NF-κB) p65, inhibitory kappa B alpha (IκB-α), c-Jun NH2-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38 induced by LPS were suppressed by schisantherin A. These findings indicated that schisantherin A exerted potent anti-inflammatory properties in LPS-induced mouse ARDS, possibly through blocking the activation of NF-KB and mitogen activated protein kinases (MAPKs) signaling pathways. Therefore, schisantherin A may be a potential agent for the prophylaxis of ARDS.