Methanol Extract of Polyopes lancifolius Inhibits the Expression of Pro-inflammatory Mediators in LPSstimulated BV2 Microglia Cells via Downregulation of the NF-kB Pathway

Purpose: This study is aimed at identifying the anti-inflammatory mechanisms of a methanol extract of Polyopes lancifolius (MEPL) in lipopolysaccharide (LPS)-stimulated BV2 microglia cells. Methods: The expression of mRNA and protein were investigated RT-PCR and western blot analyses in LPS-stimulated BV2 microglial cells. The level of nitric oxide (NO) production was analyzed using Griess reaction. The release of prostaglandin E2 (PGE2) and tumor necrosis factor-α (TNF-α) were determined using sandwich ELISA. NF-kB activation was detected using EMSA methods. Results: MEPL significantly suppressed NO production in LPS-stimulated BV2 cells without any cytotoxicity. The results also indicate that MEPL decreased the production of PGE2 and TNF-α in LPSstimulated BV2 cells. Furthermore, pretreatment with MEPL resulted in a downregulation of LPSinduced mRNA and protein expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2) and TNF-α. Investigation of the effect of MEPL on nuclear factor-kB (NF-kB) activity, which is a potential transcriptional factor for regulating inflammatory genes such as iNOS, COX-2 and TNF-α, showed that MEPL substantially inhibited the LPS-induced DNA-binding activity of NF-kB. MEPL also suppressed the LPS-induced degradation and phosphorylation of IkBα, and it consequently blocked p65 translocation from the cytosol to the nucleus. Conclusion: These data show that MEPL may regulate LPS-induced NO, PGE2, and TNF-α production by suppressing NF-kB activity.