Protective Effects of Isoliquiritigenin on LPS-Induced Acute Lung Injury by Activating PPAR-γ

Isoliquiritigenin (ILG), a major ingredient of licorice, has been reported to have anti-oxidative and anti-inflammatory effects. The aim of this study was to investigate the protective effects of ILG on lung injury using an animal model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Male BALB/c mice were conditioned with ILG 1 h before intranasal instillation of LPS. The effects of ILG on lung injury were assessed by measuring lung histopathological examination, MPO assay, wet/dry (W/D) ratio, and inflammatory cytokine production. The results showed that ILG significantly inhibited LPS-induced lung histopathological changes and the MPO activity. Meanwhile, it attenuated the wet/dry (W/D) ratio in the lung tissues. The results also indicated that ILG inhibited LPS-induced ALI in the expression of inflammatory cytokines in the BALF. Furthermore, ILG can decrease the activity of NF-kappa B and can increase the expression of PPAR-gamma. These findings suggested that ILG inhibited the inflammatory of LPS-induced lung injury by activating PPAR-gamma and inhibiting NF-kappa B activation.