Megalo-type α-1,6-glucosaccharides induce production of tumor necrosis factor α in primary macrophages via toll-like receptor 4 signaling.

The term "megalo-saccharide" is used for saccharides with ten or more saccharide units, whereas the term "oligo-saccharide" is used for saccharides containing fewer than ten monosaccharide units. Megalo-type α-1,6-glucosaccharide (M-IM) is a non-digestible saccharide and not utilized by intestinal bacteria, suggesting that ingested M-IM may encounter ileum Peyer's patches that contains immune cells such as macrophages. Macrophages are responsible for antigen incorporation and presentation during the initial step of immune responses. We investigated whether M-IMs modulate macrophage functions such as cytokine production, nitric oxide production, cell viability, and phagocytosis. Primary macrophages collected from the rats were cultured with the existence of M-IM or lipopolysaccharides (LPS). M-IM and LPS induced the production of tumor necrosis factor α (TNFα), interleukin 6 (IL6), and nitric oxide in the primary macrophages. The gene expression profile of inflammatory factors including TNFα, IL6, and ILlβ in M-IM-stimulated cells was similar to that of LPS-stimulated cells. The M-IM did not affect phagocytosis in the primary macrophages. The M-IM-induced TNFα production was suppressed in the cells treated with a tolllike receptor 4 (TLR4) inhibitor called TAK-242. In conclusion, the M-IM modulates cytokine expression via TLR4 signaling and may play a role in the modulation of immune responses.