Inhibitory Effect of Astragalus Polysaccharides on Lipopolysaccharide-Induced TNF-α and IL-1β Production in THP-1 Cells

Astragalus polysaccharides (APS), one of main bioactive components in Astragalus membranaceus Bunge, has been reported to possess anti- inflammatory activities, but the molecular mechanisms behind this activity are largely unknown. This study aimed to investigate expression of inflammatory cytokines and the MAPK/NF-kappa B pathway in human THP-1 macrophages induced by lipopolysaccharide (LPS). The results showed that the concentrations of TNF-alpha and IL-1 beta released from LPS stimulated THP-1 cells increased significantly compared to control (p < 0.01). After treatment with APS, the TNF-alpha and IL-1 beta levels were significantly lower than those in the LPS group (p < 0.05). The mRNA expression of TNF-alpha and IL-1 beta were also inhibited. Mechanistic studies indicated that APS strongly suppressed NF-kappa B activation and down-regulated the phosphorylation of ERK and JNK, which are important signaling pathways involved in the production of TNF-alpha and IL-1 beta, demonstrating that APS could suppress the production of TNF-alpha and IL-1 beta by LPS stimulated macrophages by inhibiting NF-kappa B activation and ERK and JNK phosphorylation.