Punicalagin ameliorates lipopolysaccharide-induced acute respiratory distress syndrome in mice.

Punicalagin, a bioactive ellagitannin isolated from pomegranate, has been reported to have anti-inflammatory property. In the present study, we analyzed the role of punicalagin against acute respiratory distress syndrome (ARDS) induced by lipopolysaccharide (LPS) in mice. Male BALB/c mice with ARDS, induced by intranasal instillation of LPS, were treated with punicalagin 1 h prior to LPS exposure. The effects of punicalagin on pro-inflammatory cytokines, myeloperoxidase activity, nuclear factor kappa B (NF-κB) activation, and the histopathological changes were evaluated. The results showed that punicalagin treatment attenuated LPS-induced lung edema, elevating TNF-α, IL-6, and IL-1β levels in the bronchoalveolar lavage fluid (BALF). Meanwhile, punicalagin significantly inhibited LPS-induced increases in the macrophage and neutrophil infiltration of lung tissues and myeloperoxidase activity. Furthermore, punicalagin inhibits Toll-like receptor 4 (TLR4) expression and NF-κB activation induced by LPS. In conclusion, this is the first study to demonstrate that punicalagin protects against LPS-induced ARDS in mice. The underlying mechanisms may include inhibition of TLR4-mediated NF-κB signaling pathways.