Barley-derived β-d-glucan induces immunostimulation via a dectin-1-mediated pathway

Barley-derived β-glucan, a linear mixed-linkage β-glucan composed of 1,3- and 1,4-β-d-glucopyranose polymers, binds to dectin-1. However, whether it can trigger signal transduction via dectin-1 remains unclear. In this study, we used a reporter gene assay to determine whether barley-derived β-d-glucan can activate NF-κB via dectin-1-mediated signaling when dectin-1 is cotransfected with Syk, CARD9, and Bcl10 in 293T cells. We found that barley-derived β-d-glucan can activate NF-κB leading to cytokine production when dectin-1, Syk, CARD9, and Bcl10 are coexpressed in the cells. We also found that barley-derived β-d-glucan can induce the phosphorylation of Syk and production of IL-6 in thioglycolate-elicited peritoneal macrophages. These results indicated that the immunostimulatory effects of barley-derived β-d-glucan might be exerted, at least in part, via dectin-1.