Phagocytic effects of β-glucans from the mushroom Coriolus versicolor are related to dectin-1, NOS, TNF-α signaling in macrophages

The mushroom Coriolus versicolor contains biologically active polysaccharides, most of which belong to the β-glucan group. Diverse physicochemical properties, due to different sources and isolated types of β-glucans, can induce distinct biological activities. We investigated the effects of β-glucans from C. versicolor on phagocytic activity, nitric oxide (NO), TNF-α production, and signaling of dectin-1, a well-known β-glucan receptor, in macrophages. β-Glucans increased phagocytic activity and TNF-α and NO-iNOS/eNOS production. Laminarin, a specific inhibitor of dectin-1, showed strong inhibitory effects on phagocytosis and subsequent TNF-α, iNOS, and eNOS production increased by β-glucans, indicating that β-glucans reacts with dectin-1 receptors. We examined whether the aforementioned cytokines were involved in the signaling pathway from the dectin-1 receptor to phagocytosis, and found that the inhibition of iNOS, eNOS, and TNF-α receptors significantly decreased β-glucan-induced phagocytosis. In conclusion, our study showed that dectin-1 signaling, triggered by β-glucans, subsequently elicited TNF-α and NO-iNOS/eNOS production, and that these molecules seem to act as secondary molecules that cause eventual phagocytosis by macrophages. These findings suggest that C. versicolor could be used as a nutritional medicine that may be useful in the treatment of infectious disease.