Immune effects of beta-glucan are determined by combined effects on Dectin-1, TLR2, 4 and 5

Particulate beta-glucans enhanced NF-kappa B expression in cell-lines co-expressing Dectin-1A-TLR4 and Dectin1B-TLR4, while soluble beta-glucans only synergistically acted on Dectin-IA-TLR4. This was different with Dectin-1 co-expressing TLR2 and TLR5, which inhibited activation after particulate and soluble beta-glucan stimulation. The co-acting effect of extracellular TLR2, TLR4 and TLR5 and Dectin-1 by particulate and soluble beta-glucan on cytokine production was confirmed in THP-1 macrophages. Dectin-1 activation by particulate beta-glucans during TLR2 and TLR4 but not TLR5 blocking was shown to enhance the pro inflammatory cytokines IL-6, IL-8 and TNF-alpha in THP-1 macrophages. This effect was stronger with particulate than with soluble beta-glucan. The data demonstrate that beta-glucans is an immune regulatory ligand for TLR2 and TLR4. (C) 2017 Elsevier Ltd. All rights reserved.