Immunomodulatory effect of intracellular polysaccharide from mycelia of Agaricus bitorquis (QuéL.) Sacc. Chaidam by TLR4-mediated MyD88 dependent signaling pathway

Agaricus bitorquis (QuéL.) Sacc. Chaidam is a valuable edible fungus in Qinghai-Tibet plateau and ABSP is a novel intracellular polysaccharide from its mycelia. GC and NMR analysis determined ABSP is galactoglucomannan-like polysaccharide that may have immunomodulatory effect. This study used RAW264.7 as model cell to determine immunomodulatory effect of ABSP. After ABSP treatment, viability and phagocytic ability promoted, and NO, ROS, TNF-α levels also raised which proved ABSP had immune regulation to RAW264.7. WB and qRT-PCR determined the key proteins and genes expression of TLR4, MyD88, TRAF-6 and NF-κB significantly increased while protein and gene expression of TRAM had no significant increase. Also, TNF-α level extremely decreased by adding inhibitors of TLR4 and MyD88 which confirmed ABSP could immunologically regulate RAW264.7 byTLR4-MyD88 dependent pathway. This study would provide theoretical basis for further study on ABSP and be helpful for development of beneficial functionally foods and exploitation of this resource.