Engineered Fibrosis And Particulate Nano-delivery Vehicle For Immune Enhancement Of Vaccine

In the development of vaccine,the primary goal is to design a vaccine that can effectively stimulate the immune system and trigger a protective or therapeutic immune response,while taking into account safety.In order to achieve this goal,the optimization of vaccine construction methods is crucial.Antigens and delivery vehicles are both important components of vaccines,and also the current research hotspots in this field.This article will stand upon these two sides,propose new strategies for the development of vaccines,provide unique and potential approaches for future applications and broaden the research dimension of this field.(1)Immunogenicity enhancement strategy for protein antigens based on structure reorganizationIn this study,ovalbumin(OVA),a model antigen widely used in the field of vaccine delivery,was used as the main research object.In the existing reports,researchers used OVA as a model protein antigen,and use various biological materials as the carriers,supplemented with immune adjuvants,to construct the vaccine.However,studies on designing vaccines through enhancing the immunogenicity of OVA itself have been rarely reported.Therefore,we propose a method to structurally modify OVA to induce changes in its microstructure and thus produce OVA assemblies with different morphological characteristics,including OVA spherical oligomers and OVA amyloid fibrils.By characterizing the properties of OVA assemblies,we studied the changes of different physicochemical properties of OVA during the assembly process.Through in vitro cellular assays,we demonstrated that OVA assemblies were internalized by antigen-presenting cells(APCs)and stimulated APC maturation significantly compared to natural OVA.In vivo immunization experiments showed that OVA amyloid fibrils can be used as a single-component vaccine independent of immune adjuvant,effectively enhancing the immune response triggered by OVA by increasing the titer of OVA-specific antibodies,promoting cytokine secretion,achieving immune memory effects,and prolonging antigen residence time in lymphoid organs and subcutaneous injection sites.(2)Covalent organic frameworks as novel nano-vaccine delivery vehiclesIn this study,based on current research advances in the field of nanocarriers,we explored the potential of a new class of porous framework materials,covalent organic frameworks(COF),as novel nano-vaccine delivery carriers.Trimesic aldehyde(BTCA)with symmetrical aldehyde groups,and 1,3,5-tris(4-aminophenyl)benzene(TAPB)with symmetrical amino groups were used to construct the COF.It is found that the symmetrical aldehyde groups of BTCA and the symmetrical amino groups of TAPB can form imine bonds at room temperature under the catalysis of acetic acid,based on which we constructed the basic structure of COF.In addition,we modified Resiquimod(R848),a small molecule immune adjuvant with amino groups,to the surface of COF by virtue of the free aldehyde groups,further loading the model antigen OVA to prepare COF-based nano-vaccine.Through a series of characterization tools,we demonstrated the successful preparation of COF nanocarriers as well as COF nano-vaccine in the microscopic form of homogeneous nanoparticles with a particle size of about 200 nm.Through OVA loading and release experiments,we demonstrated that COF nanocarriers are not traditional physical carriers,and the loading mechanisms for both R848 and OVA are covalent binding,and they can achieve OVA release in response to microacidic environment.Subsequently,we demonstrated that the COF nano-vaccine loaded with OVA and R848 has a strong ability to stimulate APC maturation through cellular experiments.In vivo immunization experiments demonstrated that the R848-COF-OVA nano-vaccine has good biosafety.More importantly,it has significant effects in triggering immune memory effects,increasing OVA-specific antibody titers,and the secretion level of cytokines associated with humoral and cellular immunity.