Anti-inflammatory effects on murine macrophages of ethanol extracts of Lygodium japonicum spores via inhibition of NF-kappa B and p38

Abstract

The spores of Lygodium japonicum (Thunb.) Sw. (L. japonicum) have been used in traditional Chinese medicine for the treatment of various inflammatory diseases. However, the molecular mechanisms underlying their anti-inflammatory effects have yet to be elucidated. In the present study, we investigated the anti-inflammatory effects of ethanol extracts of L. japonicum spores (ELJ) by measuring the production of inflammatory mediators, and explored the molecular mechanisms underlying the effects of ELJ in murine macrophages in vitro using immunoblotting analyses. At non-cytotoxic concentrations of (50-300 mu g/ml), ELJ was revealed to significantly suppress the production of nitric oxide (NO) and tumor necrosis factor (TNF)-alpha in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages; ELJ repressed the production of interleukin (IL)-6 only at high concentrations (>= 200 mu g/ml). The ELJ-mediated decrease in NO production was demonstrated to depend on the downregulation of inducible NO synthase mRNA and protein expression. Conversely, the mRNA and protein expression of cyclooxygenase-2 were not affected by ELJ. In addition, ELJ was revealed to inhibit the mRNA expression of IL-6, IL-1 beta, and TNF-alpha in LPS-stimulated RAW 264.7 macrophages. The effects of ELJ on proinflammatory mediators may have been due to the stabilization of inhibitor of kappa B alpha and the inhibition of p38 mitogen-activated protein kinase (MAPK). These results suggested that ELJ may suppress LPS-induced inflammatory responses in murine macrophages in vitro, through the negative regulation of p38 MAPK and nuclear factor (NF)-kappa B. Therefore, ELJ may have potential as a novel candidate for the development of therapeutic strategies aimed at alleviating inflammation.