Regulating The Functions Of Immune System To Treat Diseases By Nano Drug Carriers

Background and ObjectiveIn recent years,major diseases such as cancer,infectious diseases,and end-stage organ failure have become increasingly threatening to human health.Thus,there is an urgent need to develop new therapeutic strategies to treat these diseases.Over the past several years,immunotherapy,which enlists and strengthens the power of immune system to cure diseases,has provided a novel and powerful way to treat patients with few side effects.However,it still has many limitations,such as the therapeutic effects are usually suppressed by the microenvironment of solid tumor;targeting ability is insufficient and precise regulation of immune cell function is difficult,etc.The rapid development of nanotechnology has provided a new solution for effectively regulating immune cell function and improving the effect of immunotherapy.The composition,size,and surface properties of nano drug carriers will all have effects on the fate and drug delivery effenciency in vivo.Therefore,specifically delivery drug to immune cells can be achieved by regulating the properties of the nano drug carriers,achieving the purpose of changing the functions of immune system to improve the therapeutic effect.Methods and ResultsWe have designed and developed different treatment strategies for tumor immunotherapy and anti-transplant immune rejection by regulating the functions of immue system using nano drug carriers,which are divided into four parts:1.We studied the potential of red blood cell(RBC)-derived nanovesicles(RDNVs)as drug nanocarriers to specifically deplete macrophages.We showed that RDNVs are eff ective hydrophilic drug carriers and could eff ectively deliver drugs into macrophages both in vitro and in vivo.Nanovesicles derived from both wildtype mouse RBCs(WT-RDNVs)and CD47 KO mouse RBCs(KO-RDNVs)can encapsulate clodronate with good stability in PBS for long-term storage.However,KO-RDNVs were more efficiently engulfed by macrophages in vitro and more rapidly cleared in vivo than WT-RDNVs,indicating that CD47 also serves as a “don’t eat me” molecule for RDNVs as it does for RBCs.Accordingly,clodronate-encapsulated KO-RDNVs(KO-RDNV/CLD)were significantly more toxic to mouse macrophages in vitro than drugloaded WT-RDNVs(WT-RDNV/CLD).Furthermore,WT-RDNV/CLD showed prolonged accumulation in tissues(e.g.,liver and lung)and macrophage depletion versus KO-RDNV/CLD.Importantly,RBC-derived nanovesicles are more biocompatible and less toxic in vivo than clodronate-encapsulated liposomes-the current gold-standard macrophage-depleting reagent.This study off ers a useful strategy for macrophage-targeted drug delivery.2.We developed PLGA-PEI-p DNA microparticles and confirmed the advantage of this kind of microparticle in the endosomal/lysosomal escape process.The microparticles could be used to deliver the CRISPR/Cas9 gene editing system into antigen-presenting cells such as macrophages and dendritic cells both in vitro and in vivo.The target gene GITRL was efficiently knocked out to down-regulate the expression of GITRL.The interaction between regulatory T cells and antigen-presenting cells was changed to induce immune tolerance.We also demonstrate that this strategy can significantly prolong the survival of allogeneic skin grafts.3.We synthesized a PEGylated polylysine(Mal-PEG-PLL)modified with a maleimide group and used it to prepare the Mal-PEG-PLL-pro-IL12 nanoparticles by bounding to protamine and mouse IL-12 expression plasmid with electrostatic interaction.In vitro experiments demonstrated that the nanoparticles could effectively bind to the surface of T cell using the reaction between the maleimide group and the free sulfhydryl group(-SH)of the T cell membrane.The binding of such nanoparticles to T cells did not affect the biological functions of T cells.In vivo experiments further demonstrated that the IL-12 plasmid encapsulated nanoparticles efficiently and targetedly deliver the plasmid to tumor sites with the help of tumor-specific T cells.Using the EG-7 lymphoma bearing mouse,we found that this strategy significantly inhibited tumor growth and even had a synergistic effect.4.We synthesized a biodegradable triblock polymer(m PEG-b-PCL-PHEP-Mal)modified with a maleimide group,and prepared a nanoparticle for efficiently loading with a molecularly targeted drug-sorafenib.With the help of the reaction between maleimide group and free sulfhydryl group on the surface of CD8+ T cell,the sorafenib-loaded nanoparticles could attach onto the cell surface.Thereby,sorafenib was targeted and effectively delivered to tumor site.The tumor suppressive microenvironment was reprogramed by sorafenib,resulting in enhancing the anti-tumor effect of CD8+ T cells.In vitro and in vivo results have shown that this strategy can significantly inhibit tumor cell growth,indicating the advantages of combining chemotherapy with immunotherapy.ConclusionIn summary,we obtained four immunotherapy strategies for the treatment of cancer and organ transplantation.Therefore,it is expected to develop a new safe and efficient strategy for immunotherapy based on nano drug carriers by rational design of the properties of nano drug carriers.We provide a useful way for improving the therapeutic effect of major human diseases.