Chuanminshen violaceum polysaccharides improve the immune responses of foot-and-mouth disease vaccine in mice

Abstract

Water-soluble polysaccharides from Chuanminshen violaceum (CVPS) were evaluated for their physicochemical properties, monosaccharide composition, and adjuvant potential to specific cellular and humoral immune responses in a mouse model of foot-and-mouth disease virus (FMDV) vaccination. The average molecular weight (Mw) of the CVPS was 968.31kDa. The monosaccharide components of the CVPS was rhamnose, arabinose, fucose, mannose, glucose, and galactose with a relative mass of 6.29%, 21.87%, 16.59%, 12.54%, 13.07%, and 28.05%, respectively. Administering CVPS as an adjuvant significantly enhanced the phagocytic capacity of peritoneal macrophages, splenocyte proliferation, and the activity of NK cells and CTL as well as increased FMDV-specific IgG and IgG subclass antibody titers. Moreover, CVPS increased the expression of IL-2, IFN-γ, and IL-4 in CD4+ T cells and IFN-γ expression in CD8+ T cells. Additionally, CVPS enhanced CD40+, CD80+, and CD86+ expression on DCs. Moreover, CVPS upregulated MHC-I/II, TLR-2/4 mRNA levels. In contrast, CVPS downregulated TGF-β mRNA expression and the frequency of CD4+CD25+Foxp3+ Treg cells. Taken together, these results indicate that administering CVPS as an adjuvant enhances both cellular and humoral immune responses via the TLR-2 and TLR-4 signalling pathways, thereby promoting DC maturation and suppressing TGF-β expression and Treg frequency.