Biomimetic Hybrid Delivery System Based On Macrophage Membrane For ARDS Therapy

Acute respiratory distress syndrome(ARDS)is a common critical illness of the respiratory system,with a mortality rate as high as 40%,which greatly threatens the life and survival quality of patients.The pathological mechanism of ARDS is complex,involving a variety of inflammatory cells and mediators,which can trigger inflammatory cascade reactions,destroy lung barriers,and further cause respiratory disorders.The latest guidelines for the diagnosis and treatment of ARDS point out that early control of inflammation is of great significance for improving the oxygenation of patients and saving lives.However,there is no specific drug for ARDS treatment currently,and relevant research on drug delivery is relatively scarce.Drug delivery efficiency to lungs is quite low,and it is difficult for a single drug to prevent the progression of the inflammatory cascade effectively.M2 macrophages play an important role in reducing inflammatory responses,and their derived membrane vesicles can carry biological information and mediate immune regulatory functions.Based on this,improving the in vivo distribution of M2 macrophage membrane vesicles can promote the efficient transmission of anti-inflammatory information to the lungs,and meanwhile combining anti-inflammatory drugs to achieve multiple regulations of inflammation,is expected to solve the problem of drug delivery to the lungs and deal with the excessive inflammatory response.In this study,based on the lung inflammatory microenvironment,two biomimetic drug delivery systems were designed and constructed using the technology of membrane vesicle preparation and lipid hybrid strategy,to achieve efficient targeted therapy for ARDS.First,taking advantage of the key pathological features of increased pulmonary vascular permeability and decreased pulmonary p H in ARDS,p H-responsive biomimetic mineralized vesicles based on M2 macrophage membranes were designed.Based on the reaction of calcium ion and dexamethasone sodium phosphate,small-sized mineralized nanoparticles were prepared by reverse-phase microemulsion method.At a suitable fusion ratio,mineralized nanoparticles can hybridize with M2 macrophage membrane vesicles which form mineralized vesicles with multiple nanoparticles embedded.The mineralized vesicles possess the efficient stable drug-loading ability of nanoparticles and retain abundant functional receptors and ligands on the cell membrane surface.Compared with normal mice,the accumulation of the mineralized vesicles in the lungs of inflammatory mice was obviously enhanced,and the lung/liver ratio was increased by ~ 5.5 times at 48 h after injection,showing good tendency to inflammatory lungs and displaying penetrating ability into deep lung tissues.The mineralized vesicles could respond to an acidic inflammatory environment to release drugs,which contribute to reducing the side effects of glucocorticoids on non-target organs.In vitro evaluation of the efficacy revealed that the mineralized vesicles could combine the immunomodulatory properties of M2 macrophage membranes with the potent anti-inflammatory effect of dexamethasone,thus promoting the anti-inflammatory phenotype of macrophages,inhibiting macrophage activation,and reducing oxidative stress injury of lung epithelial cells.In ARDS mice,the mineralized vesicles could effectively inhibit the infiltration of inflammatory cells in bronchoalveolar lavage fluid,regulate the phenotype of macrophages,down-regulate the levels of multiple inflammatory factors,reduce inflammatory mediators such as myeloperoxidase and reactive oxygen species,alleviate damage to the pulmonary vascular barrier,and mitigate lung edema.Moreover,mineralized vesicles could improve the safety of glucocorticoids on the blood system,liver and kidney,which provided practical ideas for enhancing the efficacy and reducing the toxicity of clinical drugs.To further improve the lung-targeted distribution of M2 macrophage membrane vesicles,hybrid nanovesicles fused by membrane vesicles and lung-targeting liposomes were constructed.Firstly,membrane vesicles were obtained by serial extrusions of cells,and different supernatant fractions were collected during the low-speed and high-speed centrifugation steps.By evaluating and comparing the physical properties,protein retention,and in vivo and in vitro biological effects of membrane vesicles with different supernatant components,membrane vesicles were determined as the optimal part,which was further blended with liposomes to form hybrid nanovesicles through hydration and extrusion.The hybrid vesicles integrated the advantages of cell membrane and lipid materials,which could carry biological information of M2 macrophage membrane vesicles,and maintain the correct orientation and activity of membrane proteins to a certain extent.The hybrid vesicles could also retain drug-loading ability and lung-targeting properties of liposomes,thus improving lung-targeted delivery efficiency of the anti-inflammatory small molecule TPCA-1.The lung/liver ratio of hybrid vesicles was as high as 14.9,which was about 52.3 times higher than that of free membrane vesicles,and significantly elevated lung distribution in vivo.The hybrid vesicles could be efficiently taken up by pulmonary phagocytes such as macrophages and neutrophils,contributing to further targeting of key inflammatory cells and exerting anti-inflammatory effects.The hybrid vesicles effectively regulated the inflammatory macrophage phenotype and inhibited the secretion of nitric oxide and inflammatory cytokines in vitro.In ARDS mice,the hybrid vesicles inherited the immunomodulatory properties of M2 macrophages and acted synergistically with TPCA-1 to reduce the infiltration of inflammatory monocytes and neutrophils in lungs efficiently.The hybrid vesicles relieved pulmonary cytokine storm and oxidative stress,reduced reactive oxygen species,myeloperoxidase,malondialdehyde,and other pro-inflammatory mediators,and realized comprehensive regulation of ARDS.In summary,this study aims to address the core issue of improving the lung-targeted delivery of drugs and promoting anti-inflammatory effects,and proposes two biomimetic hybrid delivery strategies based on M2 macrophage membrane vesicles,by the fusion with nanoparticles and liposomes,respectively.Utilizing the ELVIS effect and characteristics of the inflammatory site,the biomimetic mineralized membrane vesicles could enhance the targeted distribution of drugs to the inflamed lungs and trigger acid-responsive release,thereby achieving the goal of increasing efficacy and reducing toxicity.Subsequently,lung-targeting phospholipids were introduced,and the hybrid nanovesicles could significantly promote lung distribution,improve the loading of the hydrophobic drug,reduce retention in non-target organs,and inhibit cytokine storms effectively.This study focuses on the drug delivery problem of ARDS and the constructed biomimetic hybrid system exhibited excellent lung delivery efficiency and mediated multi-dimensional anti-inflammatory regulatory effects,which provided a new research basis and innovative strategy for the targeted therapy of respiratory system and inflammatory diseases.