Radiation-Derived Biomimetic Nanoplatform Triggers Anti-Tumor Immunity And Mechanism Research

Objective:To construct irradiated tumor cell membrane encapsulated nano-bionic vaccine RP@RMs and explore its anti-tumor effects in different tumor models.To further investigate the mechanism of RP@RMs mediated immune system activation and antigen peptide library reconstruction by radiotherapy.Those experiments provide the theoretical and experimental foundation for the application of RP@RMs in cancer prevention and treatment.Methods:（1）The irradiated tumor cell membrane was extracted and smeared on the outer layer of nanoparticles loaded with Toll--like receptor 7 agonist Imiquimod（R837）in the framework of lactic acid-glycolic acid copolymer.A new biomimetic nano-vaccine RP@RMs was successfully constructed,and its effect on the immune system activation was investigated in vitro and in vivo.（2）Models of subcutaneous tumor,malignant pleural effusion（MPE）and lung colonization were coonstruct to explore the anti-tumor effect of RP@RMs;and to detect the anti-tumor effect of RP@RMs combined with PD-1monoclonal antibody or radiotherapy and its effect on abscopal effect;（3）To test the effect of RP@RMs on promoting antigen cross presentation by different ova cell models,and also investigate the mechanism of anti-tumor immunity induced by RP@RMs.（4）Using protein profiling to explore the mechanism by which radiotherapy remodels tumor cell membrane immunogenicity and induces the formation of antigenic peptide pools.Results:（1）RP@RMs constructed with membrane from high-dosage irradiated tumor cells significantly promoted dendritic cells（DCs）maturation in vitro.This result was further verified in lymph nodes after RP@RMs injection subcutaneously.Transcriptome sequencing showed that RP@RMs activated TLR/My D88/NF-κB pathway in DCs.（2）Subcutaneous injection of RP@RMs promote substantial and consistent anti-tumor immunity,therefore effectively prevented tumorigenesis.Flowcytometry showed RP@RMs increases the proportion of effector T cells(CD44^highCD62L^low)both in lymph node and spleen;（3）RP@RMs treatment significantly upregulated the expression of PD-L1 both in vivo in vitro,which further showed a synergistic anti-tumor efficacy when combined with PD-1 inhibitor;（4）RP@RMs can inhibit colonization of tumor cells in lung and the progress of malignant pleural effusion by reshaping immune microenvironment.In addition,RP@RMs promote abscopal effect when combined with radiotherapy;（5）After treating with RP@RMs-ova which was extracted from ova cell line membrane,DCs increased the expression of SIINFEKL-H-2Kb on its surface to initiate cross antigen presentation which was also verified in lymph nodes from mice.（6）Radiotherapy affects the process of protein degradation in tumor cells,resulting in the production of more 8-11 amino acid length peptides,which is beneficial for antigen presentation through MHC molecules.At the same time,a large number of damage-associated molecular patterns（DAMPs）proteins are enriched on the cell membrane,thereby enhancing the immunogenicity of the tumor cell membrane.Conclusion:In this study,it is the first time to construct a new biomimetic nanovaccine RP@RMs by using irradiated tumor cell membrane,and it has been proved that this vaccine can alter immune system activation.Superior anti-tumor effects have been observed in various tumor models.Tanscriptomic sequencing indicated that RP@RMs could promote antigen presentation by activating TLR/My D88/NF-κB pathway in DCs.Further experiments found that radiotherapy can enhance the immunogenicity of tumor cell membranes by affecting the enrichment of DAMPs and the formation of antigenic peptide pools.