Structure, immunostimulatory activity, and the effect of ameliorating airway inflammation of polysaccharides from Pyrus sinkiangensis Yu

Purified acid polysaccharides PSAP-1 and PSAP-2 with apparent molecular weights of 64.6 and 38.9 kDa, respectively, were isolated from Pyrus sinkiangensis Yu. through combined techniques of ion-exchange and gel permeation chromatography. Both polysaccharides were composed of predominant amounts of GalA and small amounts of Ara, Rha, and Gal. They are deduced to be native pectin-type polysaccharides containing the HG backbone consisting of α-1,4-GalAp and methyl-esterified α-1,4-GalAp residues by IR, GC-MS and NMR spectra analyses. The immunoregulatory activity test showed that PSAP-1 and PSAP-2 could increase the cell viability and the release of NO, IL-6, and TNF-α on the RAW264.7 macrophage. It indicated that PSAP-1 and PSAP-2 could increase macrophage-mediated immunostimulatory activity. The airway inflammation test of antiasthmatic mice showed that PSAP-1 could decrease the contents of IL-4, IL-5, and IL-13 and the number of inflammatory cells in BALF and improve the pathological changes in lung tissue. PSAP-1 could also decrease the amount of mucus secreted by goblet cells and the expression levels of NF-κB p65, IκBα, IKK, ERK, JNK, P38, and Muc5ac mRNA and increase the expression levels of TLR2 and TLR4 mRNA in lung tissues. This suggested that PSAP-1 may resist airway inflammation in mice. PSAP-1 and PSAP-2 had potential clinical application value.