Induction of humoral and cell-mediated immunity in mice by chitosan-curdlan composite nanoparticles administered intranasally and subcutaneously

Abstract

Infectious diseases seriously threaten human life. The need for novel delivery systems and adjuvants suitable to be used in clinic for antigens remains a challenge. Among various attempts that have been made to provide optimum immune responses for protein antigens with poor immunogenicity, polymeric nanoparticles offer great opportunities. In this study, carboxymethyl curdlan (CMC) as a polyanionic polymer and chitosan chloride (CC) and N-trimethyl chitosan (TMC) as polycationic polymers were synthesised in-house and composite nanoparticles (CC-CMC-BSA and TMC-CMC-BSA) loaded with bovine serum albumin (BSA) as a model antigen were prepared via polyelectrolyte complexation and reported here for the first time. Nanoparticles with an average size ranging from 153 nm to 615 nm, positive surface charge (from +24 mV to +55 mV) and encapsulation efficiency as high as 90% were obtained depending on the concentration of polymers in the formulation. The nanoparticles showed good physical stability for three months and low toxicity in Calu-3 and A549 cells. Furthermore, SDS integrity of antigen was maintained. In vivo studies in mice indicated that nasal and subcutaneous administration of composite nanoparticles could provide long-term humoral and cellular immunity as determined by serum antibody titres (IgG, IgG1, IgG2a) and cytokine (IL-2, IL-4, IL-6, IL-10 and IFN-γ) levels. Elevated sIgA levels after nasal administration of the nanoparticles showed that mucosal immunity was successfully stimulated. These findings suggest that chitosan-curdlan composite nanoparticles show optimum properties to be used as nanovaccine for nasal immunisation of protein antigens.