Co-delivery Doxorubicin And Interferon-gamma By Thermo-sensitive Nanocarriers For Immunochemotherapy Against Melanoma

Objectives: Chemotherapeutic drugs have been limited in the treatment of malignant tumors because of its poor specificity,which can damage normal cells when killing tumors and easily cause drug resistance.Immunotherapy has compensated the deficiency of chemotherapy,it can not only kill tumors specifically,but also increase the sensitivity of tumors to chemotherapeutic drugs.At the same time,some chemotherapeutic agents can induce anti-tumor immune responses.Combining chemotherapy and immunotherapy has become an attractive strategy for synergistic treatment of tumors.In this study,we constructed thermo-sensitive nanoparticles(TSNs),which were consisted of the PLGA core and pluronic F127 shell to co-delivery chemotherapeutic drug doxorubicin(DOX)and immunomodulator interferon gamma(IFN?)for immunochemotherapy against melanoma.Methods: TSNs were prepared by a nanoprecipitation method.Briefly,DOX was attached to the copolymer backbone of PLGA via an acid sensitive hydrazone linker or an amide linker.IFN? was absorbed into TSNs via electrostatic interaction and the thermo-sensitivity swelling/deswelling properties of F127.By comparing the in vitro cumulative release profiles and the therapeutic effects on C57BL/6 melanoma model of two polymer drug conjugates,the hydrazone bond bearing TSNs were selected.In addition,the mechanism of combination therapy was analyzed by flow cytometry,immunohistochemistry and laser confocal microscopy.Results: The drug loaded TSNs have an obvious core-shell structure and good encapsulation of DOX and IFN?.It has been shown that the p H-sensitive hydrazone bond conjugate was more likely to release DOX in a series of in vitro and in vivo experiments.Moreover,the DOX/IFN?-TSN(hyd)nanoparticles exerted an excellent anti-tumor effect on melanoma mice.It could activate Th1-type CD4+ T cell,cytotoxic T lymphocytes(CTL)and Natural killer(NK)cells to excite immune response to kill tumors.Conclusions: We successfully constructed TSNs to co-deliver chemotherapeutic drug DOX and cytokine IFN? by chemical coupling and electrostatic adsorption.In contrast to the conjugate with the amide bond-bound DOX/IFN?-TSN(ami),the p H sensitive DOX/IFN?-TSN(hyd)via hydrazone linker had exhibited faster drug release profiles in vitro and excellent anti-tumor efficiency on B16F10 tumor bearing mice.Acid-sensitive hydrazone linker could stay comparable steady in physiological environment at p H 7.4,but in endosomes and lysosomes(p H 5-6),it would bring about an intracellular p H-triggered continuous release of DOX.In addition,DOX/IFN?-TSN(hyd)absorbed more IFN? by electrostatics than amide bond conjugation.Combining the cumulative release profiles and anti-tumor effect in vivo,DOX/IFN?-TSN(hyd)have exhibited more likely to activate innate and adaptive immune responses to achieve synergistic anti-tumor effect.