Repolarized Of M2 Like TAMs By Iron-based Metal Organic Framework Loaded With Diclofenac Sodium For Tumor Treatment Research

The combination of nano-drugs and modern biomedicine provides a broad prospect for tumor treatment.The complex microenvironment in the tumor,such as dense extracellular matrix and immunosuppressive microenvironment,reduces the success rate of tumor therapy.Tumor-associated macrophages(TAMs),the key components of tumor microenvironment(TME),are classified into two major phenotypes,M1-like TAMs and M2-like TAMs.M1-like TAMs participate in the immune response,while M2-like TAMs inhibit the function of CD8~+T cells.In TME,M2-like TAMs account for the vast majority.Therefore,repolarizing M2-like TAMs to M1-like phenotype can not only reduce the tumor immunosuppression,but also stimulate anti-tumor immune response.Iron is an essential element for all organisms,which promotes cell proliferation and growth,affects tumor cell survival and tumor microenvironment reprogramming,and affects tumor development and metastasis.It has been reported that increasing the intracellular iron content of M2-like TAMs can promote their repolarization to M1-like phenotype.This may be due to the fact that M1-like TAMs display iron retention and M2-like TAMs are easy to release iron.Therefore,the targeted increase of iron content in M2-like TAMs is expected to further improve the repolarizing effects.In this study,iron-based metal-organic framework(Fe-MOF)with good biocompatibility and high drug loading was modified with M2 macrophage targeting peptide(M2pep)and then loaded with diclofenac sodium(Dic),an iron retention agent to construct Dic@M2pep-Fe-MOF for tumor therapy.In vivo and in vitro experiments show that Dic@M2pep-Fe-MOF can effectively target to M2-like TAMs and inhibit iron efflux,resulting in the promoted repolarization of M2 TAMs to M1-like phenotype.Dic@M2pep-Fe-MOF efficiently activates T cell anti-tumor immune response and improving tumor immunosuppressive microenvironment,achieving excellentanticancer effects.The main work and results of this paper are as follows:(1)Fe-MOF was prepared using Fe-TCPP and Zirconium(Zr)by solvothermal method.Fe-MOF was conjugated with M2 macrophage-targeting peptide(M2pep)by click chemistry then loaded with diclofenac sodium(Dic,an iron retention agent)to construct Dic@M2pep-Fe-MOF.Fourier transform infrared spectroscopy and UV spectrophotometer confirmed that Dic@M2pep-Fe-MOF was successful constructed.Dynamic light scattering(DLS)and electron microscope showed that Dic@M2pep-Fe-MOF was elliptical with a particle size of 100 nm and a zeta potential of-20.5 m V.(2)Dic@M2pep-Fe-MOF effectively targeted to M2-like TAMs and promoted iron retention by inductively coupled plasma atomic emission spectrometer(ICP-OES)and prussian blue staining,which may be achieved by up-regulating Hepcidin and down-regulating Ferroportin.Reverse transcription-polymerase chain reaction(RT-PCR)and flow cytometric analysis showed that Dic@M2pep-Fe-MOF effectively promoted the repolarization of M2-like TAMs to M1-like phenotype,and enhanced killing and phagocytosis on tumor cells.(3)After intravenous administration of Dic@M2pep-Fe-MOF,the contents of iron in heart,liver,spleen,lung,kidney and tumor tissue,and the changes of Ferroportin and Hepcidin in tumor tissue were detected.The results showed that Dic@M2pep-Fe-MOF could significantly increase the contents of iron in tumor tissue by up-regulating Hepcidin and down-regulating Ferroportin.Dic@M2pep-Fe-MOF efficiently inhibited the tumor growth of H22 tumor-bearing mice and extended their survival time.(4)Flow cytometric analysis showed that Dic@M2pep-Fe-MOF could effectively promote the repolarization of M2-like TAMs to M1-like phenotype in tumor tissues of H22tumor-bearing mice.Furthermore,Dic@M2pep-Fe-MOF efficiently increased the proportion of CD8~+T cells,and promoted the proliferation and activation of CD8~+T cells in tumor tissue and spleens.Meanwhile,Dic@M2pep-Fe-MOF efficiently reduced the proportion of bone marrow-derived suppressor cells(MDSC)and regulatory T cells(Treg).Thus,Dic@M2pep-Fe-MOF can enhance the anti-tumor immune response and improve the tumor immunosuppressive microenvironment.In summary,Dic@M2pep-Fe-MOF can effectively target to M2-like TAMs and promote intracellular iron retention.Dic@M2pep-Fe-MOF significantly promotes the repolarization of M2-like phenotype into M1-like phenotype,resulting in the enhanced number of CD8~+T and activated CD8~+T cells and improving tumor immune immunosuppressive microenvironment.