Cryptotanshinone inhibits prostaglandin E2 production and COX-2 expression via suppression of TLR4/NF-κB signaling pathway in LPS-stimulated Caco-2 cells

Crytotanshinone (CTN), one of the main constituents of Salvia miltiorrhiza, has been known to exhibit antioxdative, anti-inflammatory and other important therapeutic activities. The aim of this study was to evaluate the effect of CTN on prostaglandin E2 and COX-2 production in LPS-stimulated human intestinal cells (Caco-2 cells). Caco-2 cells were stimulated with LPS in the presence or absence of CTN. The production of prostaglandin E2 (PGE2) was detected by ELISA. The expression of COX-2 was detected by qRT-PCR and Western blot. The extent of phosphorylation of IκB-α, NF-κB p65 and the expression of TLR4 were detected by western blot. The results showed that CTN dose-dependently inhibited the expression of COX-2 both in mRNA and protein levels, resulting in a decreased production of PGE2. We also found that CTN suppressed LPS-induced NF-κB activation and IκBα degradation. Furthermore, CTN inhibited the expression of TLR4 up-regulated by LPS. These results suggest that CTN exerts an anti-inflammatory property by inhibiting TLR4/NF-κB signaling pathway and the release of pro-inflammatory mediators. These findings suggest that CTN may be a therapeutic agent against intestinal inflammatory diseases.