PEGylated nano-Rehmannia glutinosa polysaccharide induces potent adaptive immunity against Bordetella bronchiseptica

Vaccines, in many cases, stimulate only too weak immunogenicity to prevent infection. Therefore, adjuvants are required during their preparation to boost the immune response. We herein developed a PEGylated nano-adjuvant based on Rehmannia glutinosa polysaccharide (RGP). The addition of PEG layer exhibits enhanced immune performance of the nano-RGP. Stimulation of dendritic cells (DCs) with PEGylated nano-RGP (pRL) led to increased proliferation and cytokine production (IL-6, IL-12, IL-1β and TNF-α). The pRL was internalized into DCs via a rapid and efficient method. The mice immunized with pRL exhibited enhanced antigen-specific serum IgG and Th1-(IFN-γ), Th2-(IL-4), and Th17-(IL-17, IL-6) cytokine production, contributing to a good anti-infection performance. Furthermore, the pRL could effectively deliver the antigen to the lymph nodes (LNs), activate DC in the LN and produce enhanced CD4+and CD8+ T-cells-derived memory (CD44high CD62Lhigh), and effector (CD44high CD62Llow) as well as functional phenotypes. Our results revealed that pRL can act as a promising adjuvant with targeted delivery of antigen due to its effective activation and robust adaptive immunity induction of DCs.