Water-soluble polysaccharide obtained from Acorus calamus L. classically activates macrophages and stimulates Th1 response

A pectic polysaccharide was isolated from the rhizomes of Acorus calamus L. The main component of its carbohydrate chain was represented by residues of D-galacturonic acid (> 85%). In addition, this polysaccharide contained residues of galactose, arabinose, xylose and rhamnose (< 10%). Structural analysis of pectic polysaccharide from A.calamus L. with NMR spectroscopy indicated that it contains the regions of a linear 1,4-α-D-galactopyranosyluronan, which represents a major component of the macromolecule. A considerable amount of galacturonic acid residues was not methoxylated. We demonstrate here that the pectic polysaccharide from A. calamus L. in low concentrations was able to stimulate in vitro IL-12 and nitric oxide production by murine macrophages. It also induced TNF-α secretion by human peripheral blood mononuclear cells, reduced arginase activity but did not affect IL-10 secretion by murine macrophages or human peripheral blood mononuclear cells. The IL-12 and NO-stimulating effects on murine macrophages were similar to that of LPS. In addition, the polysaccharide promoted in vivo Th1 immune response in mice which were immunized with sheep red blood cells (DTH and quantity of plaque-forming cells) and down regulated serum level of IgG1 and IgЕ during Th2-depend immune response induced by ovalbumin. The PS increased Th1-induced edema and suppressed Th2-induced paw swelling in adoptive systems.Our results suggest that the pectic polysaccharide from A. calamus L. represents a promising immunomodulating agent that stimulates M1-polarized macrophages and promotes Th1-oriented adaptive immune response. We propose that this polysaccharide could be potentially applied for treatment of infectious, oncological diseases or for immunoglobulin-E-mediated disorders.