Polysaccharide isolated from Sarcodon aspratus induces RAW264.7 activity via TLR4-mediated NF-κB and MAPK signaling pathways.

Our previous report showed that the novel polysaccharide SAP isolated from the fruiting bodies of Sarcodon aspratus induced Hela cells apoptosis via mitochondrial dysfunction. In this study we found that SAP enhanced immunostimulatory activities of RAW264.7 cells, which was characterized by increased the production of nitric oxide (NO), reactive oxygen species (ROS), cytokines and phagocytic. However, SAP-induced macrophage activation was abolished when Toll-like receptor 4 (TLR4) signaling was blocked by anti-TLR4 antibodies. Moreover, according to the Western blot analysis and use of specific inhibitors against the MAPKs (mitogen-activated protein kinases) and NF-κB (nuclear factor-κB), we speculated that SAP activated RAW264.7 cells through TLR4-mediated activation of NF-κB and MAPKs pathways. Thus, Sarcodon aspratus is a potential immunomodulator that can be used as healthcare food.