Purpose: Herein, we reported a facile strategy for synthesis of two types of modified konjac glucomannan nanoparticles (NPs). The goal of this project was to explore the potential of the NPs as vaccine adjuvants.
Methods: Firstly, anionic carboxymethylated konjac glucomannan (CKGM) and cationic quaternized konjac glucomannan (QKGM) were synthesized by chemical modification of konjac glucomannan (KGM). Subsequently, two types of NPs, CKGM/QKGM and sodium tripolyphosphate (TPP)/QKGM, were prepared through polyelectrolyte complex method and ionic cross-linking method, respectively. The thus-synthesized NPs were then loaded with ovalbumin (OVA) to further evaluate the effect of NPs on immune response in mice.
Results: The encapsulation efficiency of OVA for CKGM/QKGM/OVA and TPP/QKGM/OVA NPs could be 49.2% and 67.7%, respectively, while the drug loading capacity could reach 10.9% and 60%. The NPs showed irregular spherical shape and exhibited good sustained-release properties. In vitro cytotoxicity assay revealed that both the blank and OVA-loaded NPs were not toxic to cells. The OVA-specific IgG, splenocytes proliferation and cytokine levels indicated that the OVA-induced humoral and cellular immune responses were up-regulated by OVA-loaded NPs. What's more, CKGM/QKGM/OVA NPs elicited both higher IL-2 and IFN-γ production, while TPP/QKGM/OVA NPs elicited both higher IL-4 and IL-10 production.
Conclusions: These results suggest that TPP/QKGM and CKGM/QKGM NPs are promising to be used as vaccine adjuvants. The TPP/QKGM/OVA NPs could induce stronger humoral immune response, while CKGM/QKGM/OVA NPs could enhance the cellular immune response more effectively.
Keywords: chemical modification; immune response; konjac glucomannan; nanoparticles; vaccine adjuvants.