Polyphyllin I alleviates lipopolysaccharide-induced inflammation reduces pyroptosis in BEAS-2B and HPAEC cells by inhibiting NF-κB signaling

Polyphyllin I is an active steroidal saponin isolated from Paris polyphylla with anti-cancer and anti-inflammatory properties. The present study investigates the role of polyphyllin I in acute lung injury. Firstly, the human bronchial epithelial cells (BEAS-2B) and human pulmonary artery endothelial cells (HPAEC) were stimulated with increasing concentrations of lipopolysaccharide at 2, 5, and 10 μg/mL. The treatment with lipopolysaccharide reduced the cell viabilities of BEAS-2B and HPAEC, downregulated superoxide dismutase (SOD) and glutathione (GSH), and up-regulated myeloperoxidase (MPO) and malondialdehyde (MDA). Moreover, the levels of TNF-α, IL-1β, and IL-6 were also up-regulated in lipopolysaccharide-treated BEAS-2B/HPAEC cells. Secondly, the lipopolysaccharide-treated cells were then incubated with different concentrations of polyphyllin I. Incubation with polyphyllin I enhanced the cell viabilities of lipopolysaccharide--treated BEAS-2B/HPAEC, up-regulated levels of SOD and GSH, and reduced MPO and MDA. Moreover, polyphyllin I reduced TNF-α, IL-1β, and IL-6 in lipopolysaccharide-treated BEAS-2B/HPAEC cells. Thirdly, the up-regulation of GSDMD-N, pro-caspase-1, and cleaved caspase-1 proteins in lipopolysaccharide-treated BEAS-2B/HPAEC cells were decreased by polyphyllin I. Polyphyllin I increased the protein expression of GSDMD-D in the lipopolysaccharide-treated BEAS-2B/HPAEC cells, and inhibited the translocation of GSDMD from cytoplasm to plasma membrane. Lastly, polyphyllin I reduced the expression of p-p65 in lipopolysaccharide-treated BEAS-2B/HPAEC cells. The over-expression of p65 counteracted with the inhibitory effects of polyphyllin I on oxidative stress and inflammation in lipopolysaccharide-treated BEAS-2B. In conclusion, polyphyllin I repressed the lipopolysaccharide-induced oxidative stress and inflammation in BEAS-2B and HPAEC, and reduced pyroptosis through inhibition of NF-κB signaling.