Anti-inflammatory activity of Dioscoreae rhizome in macrophages by inhibition of pro-inflammatory cytokines via NF-κB signaling pathway (54.11)

Abstract

Dioscoreae rhizome (DR) has been used in traditional medicine to treat numerous diseases and reported to have anti-diabetes and antitumor activities. The pharmacological and biochemical mechanisms of the water extracts of DR (EDR) on macrophages in immune responses have not been clearly elucidated. We examined whether EDR suppresses the production of pro-inflammatory cytokines and the expression of co-stimulatory molecules. EDR reduced the production of NO and PGE2 through the suppressed gene and protein expression of iNOS and COX-2 in the both RAW 264.7 cells and peritoneal macrophages. The production of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6 production were suppressed by EDR. The change of gene expression by EDR treatment was analyzed by using RT-PCR, and the associated mRNA expression was inhibited same as cytokine production. Western blot analysis showed the augmentation of cytokine related protein on EDR treatment whereas anti-inflammatory cytokines, IL-4 and IL-10, did not significantly change. The expression level of co-stimulatory molecules such as ICAM-1, B7-1, and B7-2 also was reduced with the increment of EDR concentration. The nuclear translocation of NF-κB activity in LPS-activated macrophages was suppressed by EDR. These results showed EDR decreased pro-inflammatory cytokines via the inhibition of NF-κB dependent inflammatory protein level and suggesting that how EDR could be useful immunomodulatory agent for treating immunological diseases.