Design,Synthesis And Immunological Evaluation Of Anti-Tumor Vaccines By Targeting GM3

Glycan shield is known to be covered on the cell surface,which plays an important role in cells recognition,migration and proliferation.Abnormal glycosylation,such as aberrantly glycosylation of glyprotein or glycolipids,and overpression on the tumor cells surface.These aberrant carbohydrate structure has been used to serve as a target for designing tumor vaccine.However,carbohydrate antigens are usually poorly immunogenic and T-cell-independent.Besides,tumor carbohydrate antigens are selfantigens and are tolerated by the immune system,which hinders producing of high affinity IgG antibody.So,it is a key problem to break the immune tolertence for designing carbohydrate vaccine.A traditional strategy to address this problem is to couple antigen covalently with carrier protein,which is called semi-synthetic vaccine.Carrier protein supports the T epitope to active immune system.Besides,in order to promote immune response,these semi-synthetic vaccines often mixed with adjuvant before using.Researches commonly believed co-delievery antigen and adjuvant to the same APCs can enhance the immune activation.Co-delievery method is the theme of this article,and this article is divided three parts,ⅰ)a two component co-assembling vaccine based on liposome nanoparticals;ⅱ)a full synthetic two component vaccine with build-in adjuvant,ⅲ)a semi-synthetic protein conjugate vaccine with build-in adjuvant.In chapter 2,as the lipidated can enhanced the immunogenicity,we investigated the effect of different lipid structures to antigen.So,we chose the aGalCer,the agonist of iNKT cells,as the adjuvant and co-assembled the nanoparticle with lipidated GM3.We compared three kinds of lipid structure(Pam,Pam2 and cholesterol).Though these vaccine candidates produced a similar level of cytokine in the presence of aGalCer,only the antigen modified by Pam2 stucture produced an obvious antibody titer.This vaccine candidate introduced a specific anti-GM3 IgG antibody without T epitope,which simplified the structure of carbohydrate vaccine.Then,we expored immunogenicity of the lipidated N-GcGM3 and fluorine substitution at sialic acid C-5 position.As a fully synthetic molecule of carbohudrate vaccine,this structure is homogeneous and defined,so it is more reasonable to evaluate the activity of modified antigen.Based on our result,the activity of fluorine substitution antigen is similar with nature structure GM3,but antibody-have a slightly reduced recognition to nature antigen.In chapter 3,in order to research the co-assembled vaccine and conjugate vaccine,we designed a fully synthetic two component covalent vaccine GM3-αGalCer and control vaccine candidates with the weak agonist βGalCer and Pam2 as the lipidation structure.We found co-assembled vaccine,conjugated with the suitable lipid structure,has the similar ability with GM3-αGalCer in the aspect of cytokines and antibody,but much reduced in recognition cancer cells and complement-dependent cytotoxicity experiments.In chapter 4,in order to explore immune response of toll receptor agonist in semisynthetic vaccine,we designed a semi-synthetic glyconjugate vaccine with a Toll-like receptor 7 agonist as build-in adjuvant.The result showed the self-adjuvanting semisynthetic glyconjugate vaccine produced significantly increased GM3-specific IgG antibody levels and had strong binding ability to tumor cells,which was more prior than non-covalent vaccine with TLR7 agonist,aluminium and Pam3CSK4.Comparing with GM3-αGalCer,the self-adjuvanting semi-synthetic glyconjugate vaccine changed the substypes of antibody,and the major substypes was IgG1.