Xylose rich heteroglycan from flaxseed gum mediates the immunostimulatory effects on macrophages via TLR2 activation.

Immunostimulatory activity of the flaxseed gum neutral fraction (NFG) was investigated. NFG was characterized as a xylose rich heteroglycan through monosaccharide composition analysis, FT-IR, methylation/GC-MS, and 1D/2D-NMR. NFG stimulated NO production and phagocytic activity of macrophages. Secretion of interleukin-6, interleukin-1β, and tumor necrosis factor-α (254.7 pg/mL, 2.5 ng/mL, and 42.9 pg/mL, respectively) was significantly induced by NFG. Mitogen-activated protein kinases of JNK and P38 were activated by NFG with increased phosphorylation of JNK and P38, while NO production was reduced to 6.05 and 4.42 μM by JNK and P38 inhibitor, respectively. Nuclear factor-κB signaling pathway was also activated by NFG with the suppression of IκBα and up-regulation of phosphorylation of IκBα and nuclear factor-κB P65. Toll like receptor-2 was the molecular target of NFG and responsible for the activation of down-stream signaling pathways. Thus, NFG from flaxseed gum may potentially be used as a natural immunomodulator in functional foods.