Therapeutic Effect And Biological Distribution Of Novel Polypeptide Gold Nanohybrids In Mice With Acute Lung Injury

BackgroundAcute lung injury(ALI)/acute respiratory distress syndrome(ARDS)refers to acute and progressive hypoxic respiratory failure caused by various intrapulmonary and extrapulmonary pathogenic factors other than cardiogenic factors.It is a common clinical respiratory critical disease with high incidence and poor therapeutic effect.The mortality rate is as high as 35%-46%.ALI/ARDS involves a variety of inflammatory cells and mediators.The main features of ALI/ARDS are increased alveolar capillary permeability,pulmonary edema,hyaline membrane formation,neutrophil infiltration and inactivation of alveolar surfactant.Lung imaging shows heterogeneous exudation changes.Alveolar macrophages are the source of a large number of inflammatory cytokines and play an important role in the development of ALI/ARDS.The regulation of these key cells has become the research hotspot of controlling ALI/ARDS.Toll-like receptor(TLR)is a type I transmembrane glycoprotein pattern recognition receptor,which participates in various immune responses and plays an important role in various inflammatory reactions,regulation of cell phagocytosis,cell signal transduction and cell apoptosis.TLR initiates intracellular and extracellular signaling cascades by recognizing and combining pathogen-related molecular patterns(PAMP),induces the expression of certain immune effector molecules(including inflammatory factors),and ultimately eliminates exogenous pathogenic substances to maintain homeostasis.Many studies have shown that TLR signaling pathway plays an important role in the pathogenesis of ALI / ARDS.Inhibiting TLR overactivation may be a potential method to treat hyperinflammation.TLR4 plays an important role in infectious diseases and non-infectious pulmonary inflammation.In the past decades,many TLR4 antagonists have been studied,such as small molecule inhibitors,antibodies,microRNAs,lipid A analogues and so on.So far,some of them have carried out pre-clinical studies,and few of them have undergone clinical trials,but none of them has been approved for clinical treatment.In the past decades,nanoparticles have been extensively studied in the fields of science,medicine,engineering and so on.By 2016,the FDA had approved 51 nanodrugs for treatment or imaging,and 77 nanodrugs had been tested in 18 clinical trials.In the field of medical applications,nanoparticles have been extensively studied for their good cell targeting,biocompatibility,controllable biological activity and nearly perfect pharmacokinetics.Pharmacokinetic studies on absorption,distribution,metabolism and excretion of nanoparticles are basic studies for assessing the safety and sustainability of nanoparticles.By changing the size,shape and surface chemical groups of surface substances,nanoparticles can improve the biological distribution in vivo,achieve tissue targeting and optimize the therapeutic effect.So far,many nanoparticles with different surface chemical properties have been used to solve clinical problems.Studies have shown that nanoparticles may provide a new therapeutic strategy for over inflammation by manipulating the TLR signaling pathway.We have developed a new class of polypeptide-GNP hybrid(P12)composed of gold nanonuclear and surface-coated polypeptides,which can inhibit the production of multiple TLR receptor pathways in peripheral blood mononuclear cells,including TLR2,3,4,5 and downstream pro-inflammatory factors.One of the mechanisms of anti-inflammation of P12 is to block the acidification of P12 after endocytosis.Based on previous studies,we suspect that P12 can alleviate excessive inflammation of ALI/ARDS and has broad clinical application prospects.In this paper,we mainly studied the effects of different administration modes of P12(including trachea,caudal vein and abdominal cavity)on the therapeutic effect of LPS-induced acute lung injury in mice and the distribution and difference in animals,in order to provide evidence for the next pre-clinical and clinical research of P12.Objective1.To clarify the effects of different administration modes of P12 on LPS-induced acute lung injury in mice.2.To clarify the biological distribution of P12 in mice and the factors affecting its distribution in vivo.Method1.Referring to previous literature and previous work,we synthesized polypeptide-GNP hybrid P12 and different PEG-modified polypeptide-GNP hybrid.2.Obtaining Physical Properties of Polyeptide-GNP Hybrids by Electron Microscopy and DLS.3.6-8 weeks C57BL/6 mice were given 125 nM or 500 nM 50ul P12 via trachea,abdominal cavity and caudal vein,and LPS(10mg/kg)was given after tracheotomy 2 hours after the injection of P12 to establish acute lung injury model.After 26 hours,bronchoalveolar lavage fluid was obtained for cell classification and counting.4.6-8 weeks C57 BL/6 mice were given LPS(10mg/kg)through tracheotomy to establish acute lung injury model.After 2 hours,500 nM 50 ul P12 was given via trachea.After 4 hours,lung,spleen,heart,kidney,gastrointestinal and lymph node tissues were obtained for IVIS imaging and gold content was detected by ICP-MS.5.6-8 weeks C57 BL/6 mice were given 500 nM 50 ul P12 via trachea,abdominal cavity and caudal vein.Four hours later,lung,spleen,heart,kidney,gastrointestinal and lymph node tissues were obtained for IVIS imaging and gold content was detected by ICP-MS.6.6-8 weeks C57 BL/6 mice were given 500 nM 50 ul four PEG modified GNPs via trachea.After 4 hours,lung,spleen,heart,kidney,gastrointestinal and lymph node tissues were obtained for IVIS imaging and gold content was detected by ICP-MS.ResultIn the LPS-induced ALI mice model,the total number of BALF cells and the number of neutrophils were significantly reduced by three administration modes of high concentration of P12.When low concentration of P12 was administered,intraperitoneal and caudal vein administration could not reduce the total number of BALF cells and neutrophils,but intratracheal administration still had curative effect.IVIS and ICP-MS results showed that intratracheal administration of P12 tended to accumulate in the lungs and less in the liver;intraperitoneal administration tended to accumulate in the lymph nodes;caudal vein administration tended to accumulate in the liver.P12 has unique properties and is easy to accumulate in the lungs when administered via trachea.In the presence of systemic inflammation,the accumulation of P12 in the lungs decreased and the accumulation of P12 in the spleen increaseed.ConclusionsP12 has a good therapeutic effect on LPS-induced acute lung injury in mice.Compared with tail vein and abdominal cavity administration,direct airway drip administration is more effective in treating ALI.Low dose of P12 still has a better protective effect on ALI mice,which may be related to the higher concentration of drugs in target organs and lungs.In addition,compared with the other two modes of administration,P12 airway administration accumulates less in the liver,and is easy to accumulate in the lung.This study laid an experimental foundation for accelerating the clinical transformation of P12,which is expected to become a new anti-inflammatory nano-drug for the treatment of ALI/ARDS.