Research on the Structural Features and Regulatory Effect of Polysaccharides in Ganoderma lucidum on TAMs

From the paper

Abstract

Abstract This experiment purified GLAP-2 from Ganoderma lucidum through Sepharose 6B and Sephacryl S-300 HR gradient elution, collected it by freeze-drying, and obtained GLAP-2 with a uniform molecular weight of 3.7×10⁴ Da. Its total polysaccharide content was 79.79%, and the content of galacturonic acid was 23.82%. GLAP-2 was free of protein. Infrared spectroscopy analysis indicated that GLAP-2 had characteristic absorption peaks. The results of monosaccharide composition analysis showed that GLAP-2 was composed of 1,6-Glc p residues and 1,3-Glc p residues alternately linked, with a β -glucan structure. Structure characterization revealed that GLAP-2 possessed a backbone composed of 1→4-linked β -D-Glcp, or an alternating 1→4-linked main chain of β -D-Glcp and α -D-Glcp; α -D-Manp and β -D-GlcpA are attached to the main chain as side-chain residues. The immune activity assay showed that GLAP-2 did not inhibit the growth of RAW264.7 cells, but could promote the secretion of TNF-α, NO, and IL-6 by IL-4-induced TAMs. The expression levels of TNF-α, NO, and IL-6 in M2 macrophages were significantly lower than those in M0 macrophages, and the expression levels of TNF-α, NO, and IL-6 significantly increased with the increase of GLAP-2 concentration. This indicates that our study successfully induced M2 and M1 macrophages in RAW264.7 cells using GLAP-2, and GLAP-2 can significantly inhibit the polarization of M2 macrophages and promote their transformation into M1 macrophages.