Yeast-derived β–1,3–1,6–glucan increases DC secretion of TNFα and IL-10

Abstract

The insoluble β–1,3–1,6–glucan derived from baker‘s yeast, the main ingredient in the food supplement product NutramunityTM, has been claimed to improve immune function.The aim of this study was to determine the effects of the insoluble β–1,3–1,6–glucan from baker‘s yeast and its oligosaccharide derivatives on immune responses in human dendritic cells (DCs).Human DCs were matured and stimulated in the absence or presence of different concentrations of the insoluble β–1,3–1,6–glucan and its oligosaccharide derivatives. Their effects on DC cytokine secretion and expression of surface molecules and Annexin A1 were determined using ELISA, flow cytometry, and Simple Western, respectively.Maturation and stimulation of DCs in the presence of the insoluble β–1,3–1,6–glucan led to a dose-dependent increase in their secretion of TNFα and IL-10 while maturing and stimulating the DCs in the presence of different oligosaccharide fractions had no effect on the secretion of the four cytokines tested (TNFα, IL-6, IL-12p40, and IL-10). The insoluble β–1,3–1,6–glucan increased the proportion of DCs expressing CD141 with a tendency towards an increase in the proportion of DCs expressing Dectin-1, CD14, and TLR6. The glucan decreased the proportion of DCs expressing CD86 with a tendency towards a decrease in the proportion of DCs expressing HLA-DR, CD40, PD-L1, and CD1c. Neither the β-glucan nor its oligosaccharide fractions had an effect on DC expression of Annexin A1.The increased DC secretion of both the pro-inflammatory cytokine TNFα and the anti-inflammatory cytokine IL-10 treated with the insoluble β–1,3–1,6–glucan may reflect the cytokine scenario often seen in inflammatory diseases, where IL-10 is present in conjunction with pro-inflammatory cytokines. The β-glucan in Nutramunity seems to diminish DC maturation and increase their pro-inflammatory activity. However, when DCs were treated with oligosaccharide fractions from the β–1,3–1,6–glucan the effect seen by the native compound was lost, which may be due to the oligosaccharides being smaller and perhaps having different branching structures than the native compound.