Study On The Formulation And Anti-breast Cancer Effect By PD-L1 Targeting Nanoliposomes Delivery Of STING Agonist

Immune checkpoint inhibitors combined with innate immune molecule ST ING agonists to induce tumor immune microenvironment remodeling has become the focus of anti-tumor research and drug dev elopment.Innovating the mode of drug administration to improve the synergistic effect of agonists and immune checkpoint inhibitors is a necessary way to improve the medicinal properties of ST ING agonist.In this project,the preparation of PD-L1-targeted di ABZI nano-liposomes(αdLNPs)use the nano-carrier system constructed in our laboratory.The main contents are as follows:Part Ⅰ: The preparation and characterization of αdLNPs.Blank liposomes were prepared by ethanol injection method combined with extr uder extrusion method.Anti-P D-L1 was modified on blank liposomes by DSPE-PEG2000-NHS,and di ABZI was encapsulated into liposomes by ammonium sulfate gradient method.PD-L1 targeted di ABZI nano-liposomes(αdLNPs)were prepared and characterized.The entrap ment efficiency of di ABZI was 58.29±0.53%;The results showed that the average particle size of αdLNPs was 119.43±0.66 nm,the PDI was 0.357±0.057 nm,the potential was-23.6±0.95 m V,the particle size was uniform and stable;The stability of the liposomes was analyzed,and the results showed that the prepared liposomes could be kept stably for14 days and had good stability.Part Ⅱ: The study on the effect of dLNPs on macrophages and the safety analysis in vitro.The effect of the expression of IFNβ for M2 BMDMs induced by different concentrations of free di ABZI and dLNPs was investigated.The ability of dLNPs to increase the expression of IFNβ in macrophages was significantly stronger than that of free di ABZI.The cytotoxicity of dLNPs and αdLNPs on 4T1 cells and BMDMs cells was studied by CC K-8 method.The results showed that dLNPs and αdLNPs had almost no toxicity to 4T1 cell s and macrophages.Part Ⅲ: The study on pharmacokinetics and biodistribution of αdLNPs in vivo.The results of drug metabolism study showed that αdLNPs could reduce the drug plasma clearance rate and prolong the blood circulation time,and the liposome showed a long circulation effect in vivo.The results of imaging in vivo showed that the fluorescent liposomes have stronger fluorescence signals in vivo than free fluorescent dyes,and the heart,liver,spleen,lung,kidney and tumor tissues of mice were removed after 24 hours.The results of fluorescence signal detection in vitro showed that the distribution of free fluorescent dyes in li ver and spleen was significantly less than that of liposomes,and liposomes showed longer circulatory effect in vivo.Part Ⅳ: The study on the anti-breast cancer effect ofαdLNPs in vivo.The mouse model of 4T1 was constructed,and the anti-breast cancer effect of αdLNPs in vivo was studied from two aspects of preventive effect and therapeutic effect.The results showed that αdLNPs could effectively prevent and treat breast cancer,but the therapeutic effect of di ABZI liposome without PD-L1 targeting was more obvious.In this project were based on the mouse model of spontaneous breast cancer metastasis,ST ING agonist(di ABZI)enc apsulated nano-liposomes and the PD-L1-targeted ST ING agonist nanoparticles(αPD-L1-Lipoid Nanoparticle,αdLNPs)were obtained by modifying the immune checkpoints that can bind to mouse PD-L1 molecules.Targeted delivery of STING agonist to solid tumor tissue and synergistic effect with drugs at immune checkpoints to break the immun osuppression of tumor immune microenvironment and play an anti-tumor effect.It has important theoretical significance and potential clinical application value for immunotherapy of breast cancer and other tumors.With a view to tumor immune microenvironmen t as the target of tumor immunotherapy related basic research,technology research and development to lay the foundation of preliminary work.