The Development Of Plant Polysaccharide Nano-adjuvant And Its Immune Effect

In recent years,with the continuous development of new vaccines,adjuvants have also received attention as non-specific immune enhancers that modulate the immune response of vaccines.As a traditional vaccine adjuvant,aluminum salt adjuvant has been used in a variety of vaccines,but it only induces a humoral immune response.Therefore,the ability to induce cellular immune responses is still an important goal in the development of new adjuvants.Plant polysaccharides are a class of immune enhancers with good biological safety.They can not only activate immune cells,but also promote the secretion of a variety of cytokines,enhance the stability of antigenic substances,and provide a new strategy for the development of new adjuvants.In this paper,we first investigated the activities of six plant polysaccharides（Poria cocos Polysaccharide,PCP;Coriolus versicolor Polysaccharides,CVP;Ganoderma lucidum Polysaccharides,GLP;Lycium barbarum Polysaccharides,LBP;Lentinan Polysaccharide,LNT and Astragalus Polysaccharide,APS）on the maturation of mouse bone marrow-derived dendritic cells（BMDC）.It was found that PCP effectively induced the maturation of BMDC and was thus used for the following experiments.We then investigated the adjuvant activity of PCP in vitro and in vivo.PCP was characterized with an average molecular weight of 1.28×10~4and composition of mannose,fucose,and glucose,etc.In addition,PCP was taken up by BMDC via receptor-mediated endocytosis.The CTL（cytotoxic T lymphocyte）assay showed that PCP significantly enhanced the antigen-specific killing of killer T cells in mice.When mice received three immunizations PCP and Ovalbumin（OVA）,the cellular and humoral immune response of mice were detected and results showed that PCP induced the proliferation of CD8⁺T cells and IFN-γsecreting cells,promoted the secretion of Th1 related cytokines.Furthermore,PCP significantly increased the OVA antigen-specific Ig G,Ig G2a,and Ig G1b serum antibodies.The data indicated that PCP induced Th1 immune response to ovalbumin in mice.Finally,we used Graphene Oxide（GO）as a carrier for the development of PCP/GO/OVA nanovaccine and evaluated its immune activity in vitro and in vivo.The data showed that PCP/GO/OVA induced maturation of BMDC in vitro.Immunization of mice with PCP/GO/OVA could promoted the proliferation of antigen-specific CD8⁺T cells and CD4⁺T cells,induce the secretion of Th1 and Th2related cytokines.More importantly,prophylactic vaccination of PCP/GO/OVA significantly inhibited the growth of E.G7-OVA tumors.In summary,the data revealed the immune adjuvant effect PCP and found that PCP induced Th1 and CTL effector cell differentiation.Furthermore,we developed a graphene oxide based nanovaccine PCP/GO/OVA and found it enhanced both humoral and cellular immune response,and protected mice from tumor challenge.The data will provide a new strategy for new adjuvants development.