1 research outputs found
Inducement of Cytokine Release by GFPBW2, a Novel Polysaccharide from Fruit Bodies of Grifola frondosa, through Dectin‑1 in Macrophages
Polysaccharides, especially β-glucans
isolated from various species of mushrooms, are considered as biological
response modifiers (BRMs) to be widely used in the treatment of cancer,
especially due to their immunostimulatory activity. We herein characterized
the structure of a novel water-soluble homogeneous polysaccharide
(GFPBW2) from the fruit bodies of mushroom Grifola
frondosa and investigated its immunomodulatory activity
in vitro. GFPBW2 was purified from the alkali-extracted fractions
by stepwise elution with a molecular weight of 26.2 kDa. On the basis
of infrared and NMR spectroscopy, methylation and monosaccharide composition
analysis, partial acid hydrolysis, and Smith degradation, its structure
was elucidated to possess a backbone consisting of β-d-1,3- and β-d-1,4-linked glucopyranosyl residues,
with branches attached to <i>O</i>-6 of β-d-1,3-linked glucopyranosyl residues. Functionally, it is an effective
inducer of tumor necrosis factor-α (TNF-α) and interleukin-6
(IL-6) secretion in murine resident peritoneal macrophages. Using
quartz crystal microbalance (QCM) analysis, we found that GFPBW2 could
bind dendritic cell-associated C-type lectin-1 (Dectin-1) with an
affinity constant (<i>K</i><sub>d</sub>) value of 1.08 ×
10 <sup>–7</sup> M, while it could activate Syk and enhance
TNF-α production in RAW264.7 cells overexpressing wild type
but not mutant Dectin-1. Furthermore, Syk, NF-κB signaling,
and cytokine release in resident peritoneal macrophages induced by
GFPBW2 could be significantly inhibited by a specific Dectin-1 blocking
reagent, Laminarin. These data suggested that GFPBW2 might be a potential
ligand of Dectin-1, and the potential of GFPBW2 to activate macrophage
through triggering cytokine secretion might be attributed, at least
in part, to the involvement of Dectin-1