Application Of Layered Double Hydroxide Nanoadjuvant For Cancer Immunotherapy

Cancer therapeutic vaccine can promote body forms specific anti-tumor immunity to kill tumor cells,inhibit the growth,metastasis and recurrence of malignant tumors,showing ideal clinical application prospects.However,little vaccine adjuvants can efficiently induce T-cell immune responses,as well as the tumor immune tolerance and poor vaccine in vivo delivering process,resulting in limited therapeutic efficacy and clinical application of cancer therapeutic vaccines.To address these issues,a new type of aluminum adjuvant(magnesium-aluminum laydered double hydroxide;LDH)combined with immunoregulatory molecules was used in this study.Basedly,three kinds of multifunctional cancer therapeutic vaccines which aim to overcome tumor immune tolerance and loss or mutation of cancer epitopes,as well as optimized vaccine subcutaneous delivery and novel administration routes were developed,significantly enhancing the immune induction efficiency and therapeutic efficacy of cancer therapeutic vaccine.The specific research work is as follows:1.The LDH nanovaccines(TLIs)co-delivered with IDO inhibitor(siIDO)and the melanoma antigen Trp2 were prepared to alleviate the immunosuppressive status of dendritic cells(DC)and promote antigen-specific immune responses.In tumor patients,pro-inflammatory cytokines released by tumor cells leads to over-expression of indoleamine 2,3-dioxygenase(IDO)in DC cells,which in turn affects tryptophan metabolism and changes the DC function from immune activation to immunesuppressive.TLIs have rapid DC endosomal escape ability,and can quickly release siIDO and Trp2 to the cytoplasm.On the one hand,siIDO down-regulates the level of IDO and promotes DC activation by interfering with the expression of IDO mRNA.On the other hand,Trp2 binds with the major histocompatibility complex(MHC)I molecule and is presented to the cell surface,thereby effectively promoting antigen specific T cell immune response to eliminate tumor.2.The LDH trivalent vaccine(s-BmALC)which consists of tumor classical antigen Trp2,mutant epitopes M27 and M30,and CpG,can elicit a broad-spectrum antitumor immune response and significantly improve the therapeutic efficacy of cacner therapeutic vaccine.Once the s-BmALC was internalized by DC,the CpG and epitopes were released during the acidification of the endosome,and then can quickly promote these cargoes escape into the cytoplasm.Especially,the released CpG binds to the endosomal or lysosomal TLR-9 receptor to promote the activation of DC.The released antigens are further processed in the cytoplasm,then bind to MHC class I molecules and are presented by DC to induce a broad spectrum of antigen-specific T cell immune responses.Compared with traditional monovalent vaccines,trivalent vaccines can induce a broader spectrum of T-cell immune responses,more efficienctly inhibit tumor growth and avoid the off-targets of antigen-specific T-cell immune immune response.3.The multifunctional LDH nanoadjuvant combined with photothermotherapy and chemotherapy was prepared to induce a strong in situ anti-tumor immune response.FDA-approved indocyanine green(ICG),doxorubicin/DNA complex prodrug(Dox/DNA),and CpG were loaded in LDH to obtain a multifunctional LDH nanoadjuvant(IDCB-LDH).IDCB-LDH can be efficiently enriched in tumors,and ICG can rapidly heat tumors to?55? under the induction of a 808 nm laser to thermally kill the tumors.Meanwhile,the DNA in Dox/DNA(Tm=40.5?)rapidly unwinds and releases Dox as the temperature of tumor increased,further killing tumor cells and releasing a large amount of tumor antigens.Subsequently,LDH/CpG binds these antigens in situ and presents them to DC,triggering strong antigen-specific T cell responses,effectively removing the residual tumor tissue,and preventing tumor recurrence and metastasis.4.The study clarified the relationship between the in vivo dispersity of LDH vaccine and its anti-tumor immune response inducing efficiency.Benefited from the albumin-coating technology,LDH vaccines at monodispersed statue(s-BTLC)and aggregated statue(a-BTLC)under physiological conditions were prepared.The results show that s-BTLC can actively infiltrate into lymph nodes(LNs)and promote the uptake of vaccines by more antigen-presenting cells(APC)in a short time,thereby significantly enhancing the efficiency of cellular immune response inducing efficiency.In contrast,a-BTLC aggregated mainly remained at the injection site and the infiltration of LNs was inefficient,resulting poorer anti-tumor immune response.5.The spleen-targeted LDH vaccine delivery can rapidly induce a strong anti-tumor immune response.Malignant tumors usually grow rapidly and have high lethality,which requires high timeliness of vaccines.However,most of the current cancer therapeutic vaccines are ineffective in the treatment of advanced tumors.Intravenous(IV)injected LDH vaccine can rapidly enrich the spleen and induce a strong T cell immune response.Based on this,a new vaccine administration strategy ?+SC was designed by combined with subcutaneous injection(SC).That is,in the early stage of the tumor,the vaccine is injected through the ? route to rapidly trigger an immune response,and then the vaccine is injected through the SC route to continuously stimulate the immune system to achieve a combination of "rapid and strong immune response" and "long-term immune stimulation",thereby suppressing the tumor more efficiently.Interestingly,the simultaneous injection of the vaccine by ? and SC routes can trigger a stronger T cell immune response and significantly inhibit the growth of advanced tumors.