| The combination of biomaterials and immunotherapy has attracted wide attention.Biomaterial-mediated vaccine delivery plays a strong role in immunotherapy.With the development of new materials and technology,it is an interesting research direction to enhance the immune response of the vaccine in the field of immunotherapy.It is worth noting that multifunctional vaccine delivery system promotes an intense effect on immune system with the combination of immune adjuvants or other therapeutic methods,eliciting the rapid and continuous presentation of antigens and inducing stronger antitumor immune response.Meanwhile,it is essential to track the process of vaccine delivery and treatment including the localization and distribution of tumor antigen,the delivery and migration of immune adjuvants.With the development of multispectral fluorescence imaging technology,the visible fluorescent vaccine delivery system and cancer immunotherapy provide a promising prospect in precise tumor therapy.In this study,three visible fluorescent vaccine delivery systems were constructed for cancer immunotherapy including combined ovalbumin(OVA)nanovaccine,co-delivery nanovaccine of antigen and adjuvant,nanoparticles-loaded photothermal hydrogel.A stronger immune response can be stimulated to enhance antitumor immunotherapy by sustained delivery of antigen,co-delivery of antigen and adjuvant or combined photothermal immunotherapy.Furthermore,the vaccine system can be tracked in real-time to monitor the location and degradation of each component of the vaccine in cancer immunotherapy by multispectral fluorescence imaging.This project is divided into three parts as follows.In the first part,a visible combined OVA nanovaccine was developed to promote immune response.The inner layer of the combined nanovaccine consisted of genipin-cross-linked polyethyleneimine-antigen nanoparticle carrying abundant antigens by self-cross-linking for persistent immune response.The outer antigen can exert a fast delivery to induce the initial antigen exposure.The programmed delivery of the inner and outer antigens will induce strong immune responses with a combination of a quick delivery and a persistent delivery.With adequate antigen exposure,dendritic cells(DCs)were effectively activated and matured,stimulate the activation of T cells in order to induce a strong immune response.Compared with single nanoparticles,the combined nanovaccine can induce stronger antigen-specific immune response,antigen-specific CD4 and CD8+T cell response,immune memory and CD8+ cytotoxic T lymphocyte(CTL)response.Moreover,the inner and outer antigens of combined vaccine can be tracked with a programmed delivery by dual fluorescence imaging.The delivery of combined nanovaccine was monitored dynamically in real-time to realize the precise delivery of double layer antigens.In the second part,a visible codelivery nanovaccine of an antigen and adjuvant based on self-cross-linked antigen nanoparticles(ovalbumin nanoparticles(ONPs))combined with the adjuvant(CpG)for cancer immunotherapy was prepared using antigens themselves as carriers.OVA nanoparticles(ONPs)not only provide sufficient antigens for continuous stimulation of the innate immunity and adaptive immunity with high antigen loading efficiency,but also serve as carriers of CpG.In vitro and in vivo experiments provided that OVA nanoparticles deliver CpG to immune cells via intracellular pathway,enhancing the immunological activity of CpG,thus further induces DCs maturation,T cell activation and the production of interferon-?(IFN-?).ONPs-CpG induced strong tumor-specific immunity and exhibited remarkable antitumor immunotherapy effects in vivo using mouse models of lymphoma.In addition,in order to perform precise vaccine delivery,the dual fluorescent co-delivery nanovaccine was monitored in real time in vivo by the visible imaging method,which provided a visual basis for the tracking of antigen and adjuvant in cancer immunotherapy.In the third part,a dual self-fluorescence vaccine system of IR820 hydrogel carried with CpG self-crosslinked nanoparticles was constructed to realize combined photothermal immunotherapy.The combination of CpG self-crosslinked nanoparticles and IR820 hydrogel can release both CpG and photothermal induced tumor antigen,and further enhance the effect of immunotherapy.IR820-hydrogel combined with CpG nanoparticles provided the synergistic photothermal immunotherapy,promoting the maturation of BMDCs,the increase of CD8+T cells,the secretion of IFN-y and IL-2,and the specificity of CTL,which stimulated the specific antitumor immune response.The mechanism of combined antitumor effect was further revealed by analyzing the immune cells such as CD8+T cells,DCs,Tregs and MDSC in tumor microenvironment.In the combined photothermal immunotherapy group,the number of CD 8+T cells and DCs increased in the tumor microenvironment,resulting in a strong synergistic effect of antitumor immune response.The decreased immunosuppressive cells such as Tregs and MDSC promoted the antitumor effect of CTL and the secretion of related cytokines,regulating the tumor microenvironment and enhancing the cancer therapeutic effect.In addition,IR820-hydrogel and CpG nanoparticles exerted the imaging-guided combined photothermal-immunotherapy by the dual fluorescence imaging method without additional fluorescent labeling.This visible combined photothermal-immunotherapy offers a potential for precise cancer treatment.In summary,three imaging-guided visible vaccine delivery systems for tumor immunotherapy and combined photothermal-immunotherapy were successfully constructed based on the self-fluorescence vaccine delivery system of OVA/CpG self-crosslinked nanoparticles and IR820-hydrogel,which could produce stronger immune response or antitumor effect.Furthermore,imaging tracking of the multi-component vaccine delivery system by multispectral fluorescence technology provided a visible basis for precise tumor therapy.It would provide guidance for the design of vaccine delivery systems in new immunotherapy and combination therapies. |
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