The Immunologically Active Oligosaccharides Isolated from Wheatgrass Modulate Monocytes via Toll-like Receptor-2 Signaling

Wheatgrass is one of the most widely used health foods, but its functional components and mechanisms remain unexplored. Herein, wheatgrass-derived oligosaccharides (WG-PS3) were isolated and found to induce CD69 and Th1 cytokine expression in human peripheral blood mononuclear cells. In particular, WG-PS3 directly activated the purified monocytes by inducing the expression of CD69, CD80, CD86, IL-12, and TNF-α but affected NK and T cells only in the presence of monocytes. After further purification and structural analysis, maltoheptaose was identified from WG-PS3 as an immunomodulator. Maltoheptaose activated monocytes via Toll-like receptor 2 (TLR-2) signaling, as discovered by pretreatment of blocking antibodies against Toll-like receptors (TLRs) and also determined by click chemistry. This study is the first to reveal the immunostimulatory component of wheatgrass with well defined molecular structures and mechanisms. Background: Wheatgrass is a supplemental food that enhances immunity and improves various diseases; however, there remains a lack of scientific evidence for this. Results: Wheatgrass-derived α-(1,4)-linked heptaglucan maltoheptaose systematically increases immune activation. Conclusion: Maltoheptaose is an immune stimulator that activates monocytes via Toll-like receptor-2 signaling. Significance: This is the first work to address the immunostimulatory component of wheatgrass with well defined molecular structures and mechanisms.