The Effect Of Tumor Microenvironment Regulation With Active Immune Against FGF-2 On A Therapeutic HPV Vaccine

Background:Therapeutic vaccination appears to be a potent approach for the treatment of human papillomavirus(HPV)-associated tumors;however,its clinical efficacy is currently thought to be largely limited by immunosuppressive mechanisms developed during tumor growth.FGF-2 is an important tumor proangiogenesis factor accumulates in many tumor tissues,which promotes tumor angiogenesis,tumor cell proliferation,and migration,and abnormal proliferation of tumor tissue blood vessels promotes tumor tissue anaerobic microenvironment,further promotes the differentiation,proliferation,and proliferation of immune suppressor cells infiltration into tumor tissue.Therefore,antagonizing the abnormal accumulation of FGF-2 in tumor tissues may plan an important role in overcoming tumor immunosuppression and stimulating anti-tumor immunity to enhance the effect of tumor vaccines.Objective:This study we constructed a vaccine targeting FGF-2 through gene recombination,and induced persistent FGF-2 antibodies in the mice through active immunization to antagonize the pathological function caused by FGF-2,aimed to investigate whether active immunization against FGF-2 could modify antitumor immunity and enhance the efficacy of an HPV16 E7-specific therapeutic vaccine.Methods:The recombinant FGF-2 B cell epitope antigen peptide was presented on the surface of hepatitis B core antigen(HBcAg)virus-like particles(VLPs)by gene recombination technology,and purified to prepare recombinant VLP vaccine.Mice bearing TC-1 tumors were immunized with the VLPs alone or in combination with an HPV16 E7-specific vaccine.Results:Recombinant VLP vaccines presenting four FGF-2 antigen peptides(P3、P5、P11、P12)were successfully prepared.The PBS buffer containing 1 mol/L urea was used to effectively dissolve the aggregated VLPs.The typical HBcAg VLPs behavior was exhibited in sucrose density gradient centrifugation.Purified,PBS containing 30%sorbitol effectively avoids the re-aggregation of urea after removal.In the therapeutic intervention of tumor-bearing mice,recombinant protein was VLP immunization produced a persistent and high-titer FGF-2-specific antibody response.FGF-2-P3,P5,P11 VLP vaccines and HPV antigen-specific therapeutic vaccines did not show ideal synergistic anti-tumor and tumor growth inhibitory effects;For FGF-2-P12 VLP located in the heparin binding domain,compared with either immunization alone,combined immunization targeting both FGF-2 and E7 significantly suppressed tumor growth,;Flow cytometry analysis showed that the levels of IFN-γ-expressing splenocytes and effector CD 8+T cells(cytotoxic T lymphocytes,)in both the spleen and tumor was significantly increased,and the levels of immunosuppressive cells such as Tregs(regulatory T cells,)and MDSC(myeloid-derived suppressor cells)in both the spleen and tumor was significantly decreased;Immunofluorescence showed that the infiltrating CD8+T cells in the tumor tissue of combined immunization significantly increased,and the Gr-1+cells significantly decreased.In addition,immunohistochemistry showed that the levels of FGF-2 and neovascularization in tumors were significantly decreased in the mice receiving the combinization,and the levels of granzyme B and tumor cell apoptosis molecule Casepase3 were significantly increased.Conclusion:The combined use of urea and sorbitol provides an effective solution for the purification and preparation of VLPs with aggregation phenomena;The combination of an HPV16 E7-specific vaccine and active immunization against FGF-2 significantly enhances antitumor immune responses in mice with TC-1 tumors,indicating a promising new strategy for tumor immunotherapy.