Structure elucidation and immunomodulatory activity of a beta-glucan derived from the fruiting bodies of Amillariella mellea

A novel polysaccharide AAMP-A70 (5.6 kDa) has been purified from the fruiting bodies of Amillariella mellea. Compositional analysis and 1H and 13C NMR spectra indicate that AAMP-A70 is a branched beta-glucan with a main chain that consists of beta-D-(1 -> 6) linked Glc rho residues substituted at O-3 by beta-Glc rho or alpha-D-(1 -> 6)-linked Gal rho side chains. AAMP-A70 increases macrophage phagocytosis and secretion of NO, ROS, TNF-alpha, IL-6 and IL-1 beta. Mechanistically, AAMP-A70 promotes degradation of I kappa B-alpha and nuclear translocation of the NF-kappa B p65 subunit, and enhances phosphorylation of MAPKs. In particular, the function blocking antibody to TLR2 substantially suppresses TNF-a and IL-6 production. Our data demonstrate that AAMP-A70 activates macrophages via NF-kappa B/MAPK signaling pathways and the TLR2 receptor. Overall, AAMP-A70 may serve as a good food supplement to enhance immunity.