The Immunomodulatory Activity of Polysaccharides from the Medicinal Mushroom Amauroderma rude (Agaricomycetes) is Mediated via the iNOS and PLA2-AA Pathways

: Our earlier work indicated that the polysaccharides of Amauroderma rude (AR) appear to have an effect on immunoregulation. However, the pathways are not clear. In this paper, we discuss the immunomodulatory mechanisms of A. rude to provide a scientific basis for its possible use as a food. Amauroderma rude increased the expression of iNOS and P38 in the Raw246.7 cell line. When the AR concentration reached 150 μg/mL, the expressions of iNOS and P38 increased 23.0% and 191.7%, respectively. When the AR concentrations were 50 μg/mL, the concentrations of cytokines IL-2, TNF-α, and IFN-γ were 33.65 pg/mL, 12.53 pg/mL and 42.56 pg/mL. When AR reached 200 μg/mL, the lgA and lgM levels were 0.73 μg/mL and 1.5 μg/mL. When AR reached 400 μg/mL, the lgG level reached 1.65 μg/mL by ELISA assay. When 4.8 mg AR were orally administered, IL-2, TNF-α, IFN-γ, PGE2, and LTB4 increased dramatically, to 0.17 pg/mL, 0.16 pg/mL, 0.15 pg/mL, 30.71 pg/mL, and 18.68 pg/mL, respectively. The concentrations of lgA, lgM, and lgG, AA, and PLA2 also increased significantly to 2.62 pg/mL, 2.14 pg/mL, 2.06 pg/mL, 5.23 μg/mL and 3.68 ng/mL, respectively. With 4.8 mg AR p.o., iNOS protein expression increased 16.8% and P38 increased 234.0%. These results indicate that A. rude polysaccharides stimulate cytokine production and activate the iNOS, PLA2-AA, and MAPK pathways during the immunomodulatory process.