Shionone Relieves LPS-Induced Acute Lung Injury by Regulating the TNIP2/NF-kB Pathway

Acute lung injury, a diffuse inflammatory injury caused by various factors, is characterized by respiratory distress and progressive hypoxemia. Shionone is a natural triterpenoid with anti-inflammatory activity. Here, we aimed to investigate the effects and action mechanisms of shionone on lipopolysaccharide-induced A549 cells. Lipopolysaccharide-stimulated A549 cells were used as an in vitro acute lung injury model. Lactate dehydrogenase, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, and flow cytometry assays were used to assess lactate dehydrogenase activity, viability, and apoptosis in A549 cells, respectively. Reactive oxygen species accumulation and superoxide dismutase and catalase activities were analyzed using kits. Levels of the inflammatory cytokines, interleukin-6, interleukin-1 beta, and tumor necrosis factor-alpha were assessed via enzyme-linked immunosorbent assay. Apoptosis-related (cleaved caspase-3) and TNFAIP3-interacting protein 2 (TNIP2)/nuclear factor (NF)-kappa B pathway protein levels were measured via quantitative reverse transcription-polymerase chain reaction and western blotting. Shionone did not exhibit cytotoxicity in A549 cells. It markedly increased the viability, reduced the apoptosis, and inhibited cleaved caspase-3 levels in A549 cells compared to those in lipopolysaccharide-stimulated cells. Shionone also inhibited lipopolysaccharide-stimulated inflammation and oxidative stress, as indicated by the reduced reactive oxygen species release, increased superoxide dismutase and catalase activities, and decreased interleukin-6, interleukin-1 beta, and tumor necrosis factor-alpha levels. It significantly attenuated lipopolysaccharide-induced activation of the TNFAIP3-interacting protein 2/nuclear factor-kappa B pathway, thereby increasing TNFAIP3-interacting protein 2 mRNA and protein levels and decreasing p-65 levels and p-p65/p65 ratio. However, these effects were partially reversed by TNIP2-siRNA. Overall, this study revealed that shionone exerted protective effects against lipopolysaccharide-induced acute lung injury by regulating the TNFAIP3-interacting protein 2/nuclear factor-kappa B pathway, highlighting its potential for acute lung injury treatment.