Enhancement of the immune responses to foot-and-mouth disease vaccination in mice by oral administration of a Novel polysaccharide from the roots of Radix Cyathulae officinalis Kuan (RC)

Foot-and-mouth disease (FMD) is a kind of the important animal infectious disease caused by the foot-and-mouth disease virus (FMDV). Thus, the aim of this study was to determine the effects of the polysaccharide from the Radix Cyathulae officinalis Kuan (RCPS) for its adjuvant potential on the FMDV-specific cellular and humoral immune responses in mice. In this study, our findings shows that oral administration of RCPS significantly enhanced the phagocytic capacity of peritoneal macrophage, splenocyte proliferation, the activity of natural killer (NK) cells and cytotoxic T lymphocytes (CTL) and IgG, IgG1, IgG2a, and IgG2b antibody titers. Furthermore, RCPS promoted the level of IL-2, IFN-γ and IL-4 in CD4+T cells and level of IFN-γ in CD8+T cells. In addition, RCPS enhanced the expression of CD40+, CD80+ and CD86+ on DCs. Importantly, RCPS could up-regulated the mRNA level of MHC I, MHC II, TLR-2, TLR-4. Interestingly, RCPS down-regulated the frequency of CD4+CD25+Foxp3+Treg cells. Taken together, these results demonstrate that RCPS can enhance both cellular and humoral immune responses via up-regulating DCs maturation through TLR2, TLR4 signaling pathway, and suppressing Treg frequency.