Platycodin D Inhibits Inflammatory Response in LPS-Stimulated Primary Rat Microglia Cells through Activating LXRα-ABCA1 Signaling Pathway

Platycodin D (PLD), an effective triterpenesaponin extracted from Platycodon grandiflorum, has been known to have anti-inflammatory effect. In the present study, we investigate the anti-inflammatory effects of PLD on LPS-induced inflammation in primary rat microglia cells. The results showed that PLD significantly inhibited LPS-induced ROS, TNF-alpha, IL-6, and IL-1 beta production in primary rat microglia cells. PLD also inhibited LPS-induced NF-kappa B activation. Furthermore, our results showed that PLD prevented LPS-induced TLR4 translocation into lipid rafts via disrupting the formation of lipid rafts by inducing cholesterol efflux. In addition, PLD could activate LXR alpha-ABCA1 signaling pathway which induces cholesterol efflux from cells. The inhibition of inflammatory cytokines by PLD could be reversed by SiRNA of LXRa. In conclusion, these results indicated that PLD prevented LPS-induced inflammation by activating LXR alpha-ABCA1 signaling pathway, which disrupted lipid rafts and prevented TLR4 translocation into lipid rafts, thereby inhibiting LPS-induced inflammatory response.