4-Hydroxy-17-methylincisterol from Agaricus blazei Decreased Cytokine Production and Cell Proliferation in Human Peripheral Blood Mononuclear Cells via Inhibition of NF-AT and NF-κB Activation.

Agaricus blazeiMurill is an edible andmedicinalmushroom. In the previous study, we have proved that extracts of A. blazei inhibit human peripheral blood mononuclear cell (PBMC) proliferation activated with phytohemagglutinin (PHA). Currently, we purified 4-hydroxy-17-methylincisterol (4-HM; C21H33O3) from A. blazei investigated its regulatory effects on cytokine productions and cell proliferation of PBMC induced by PHA. The results indicated that 4-HM suppressed, in activated PBMC, the production and mRNA expression of interleukin-2 (IL-2), IL-4, tumor necrosis factor-alpha, and interferon-gamma in a concentration-dependent manner. This inhibition was not related to cell viability. While 4-HM did not affect ERK phosphorylation and its downstream c-fos gene expression in PBMC induced by PHA, it decreased both NF-AT and NF-kappa B activation. The upstream signaling of NF-AT and NF-kappa B, intracellular calcium concentrations ([Ca2+](i)), and protein kinase C theta (PKC theta) activation in PHA-treated PBMC were reduced by 4-HM. The data demonstrated that the suppressant effects of 4-HM on cell proliferation in PBMC activated by PHA appeared to be mediated, at least in part, through inhibition of Ca2+ mobilization and PKC theta activation, NF-AT and NF-kappa B activation, and cytokine transcripts and productions of PBMC. We suggested that A. blazei contained a potential immunomodulator 4-HM.