Crude polysaccharide from the milky mushroom, Calocybe indica, modulates innate immunity of macrophage cells by triggering MyD88-dependent TLR4/NF-κB pathway.

Objectives: Calocybe indica is a famous nutritious food in Asian countries and one of the most widely cultivated mushrooms in the world. Here, we have isolated crude polysaccharides from this mushroom, characterized it and investigated its antioxidant and immunostimulatory potential.

Methods: The polysaccharide was chemically characterized by spectrophotometry, FTIR and high-performance thin layer chromatography and tested its antioxidant potential by in vitro assays. Immunomodulatory activity and its underlying signalling process were ascertained in RAW 264.7 cells.

Key Findings: The polysaccharide consisted of D-glucose (β-linked sugars), D-mannose and D-galactose, where backbone was organized in random coil structure. Preliminary investigation of the bioactivity of the polysaccharide revealed its antioxidant potential. The polysaccharide could noticeably induce phagocytic activity and production of immune mediators in macrophage cells. The polysaccharide was found to enhance the expression of pro-inflammatory cytokines and activate NF-κB signalling pathway by overexpressing MyD88, Iκ-Bα and NF-κB. Further studies indicated the polysaccharide binds to the toll-like receptor 4 to manifest its immunostimulatory activity in macrophage cells.

Conclusions: Our findings indicate potential therapeutic properties of the crude polysaccharide of C. indica which might provide the means to treat various radical induced and immunodeficiency disorders in the days to come.