Fraxin ameliorates lipopolysaccharide-induced acute lung injury in mice by inhibiting the NF-κB and NLRP3 signalling pathways

Fraxin, the effective component of the Chinese traditional medicine Cortex Fraxini, is reported to have anti-inflammatory effects. This study assessed the anti-inflammatory effect of fraxin on the lipopolysaccharide (LPS)-induced inflammatory response in A549 cells and the protective efficacy on LPS-induced acute lung injury (ALI) in mice. Fraxin reduced LPS-induced TNF-α, IL-6 and IL-1β production in A549 cells and alleviated the LPS-induced wet/dry (W/D) weight ratio and the effects observed via histopathological examination of the lung in vivo. Furthermore, fraxin reduced the protein concentrations in the broncho-alveolar lavage (BAL) fluid and cytokine production in the sera. Fraxin also clearly attenuated the oxidation index, including the activity of myeloperoxidase (MPO), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH). Immunohistochemistry analysis showed that fraxin suppressed LPS-induced inflammatory damage. The expression of proteins involved in the NF-κB and NLRP3 inflammatory corpuscle signalling pathways was consistent between the lung tissues and cell samples. Overall, fraxin played a protective role in LPS-induced lung injury by inhibiting the NF-κB and NLRP3 signalling pathways.