Role And Mechanism Of Macrophages In Alleviating Cardiac Ischemia-Reperfusion Injury By SDR5-fc

BackgroundMyocardial infarction(MI)caused by a variety of factors,is a syndrome which features coronary artery blockage,blood flow disorders,and eventually lead to myocardial ischemia and hypoxia.With the development of science and technology,the incidence of myocardial infarction has been increasing year by year.Currently,the clinically effective treatment is coronary artery recanalization,but ischemia-reperfusion(I/R)injury occurs when the coronary artery is recanalized.I/R injury leads to the activation of cell death programs,including apoptosis(nuclear fragmentation,plasma membrane blebbing,cell shrinkage and loss of mitochondrial membrane potential and integrity),autophagy-associated cell death(cytoplasmic vacuolization,loss of organelles)and necrosis(progressive cell and organelle swelling,plasma membrane rupture and leakage of proteases and lysosomes into the extracellular compartment).I/R injury is a complex,multifactorial process involving many factors such as calcium overload,oxidative stress,mitochondrial dysfunction,apoptosis and inflammation.In the early stage of cardiac I/R,peripheral blood leukocytes,including macrophages and monocytes,rapidly recruit to sites of ischemia and participate in inflammatory reactions.Our previous results displayed that TNF-related apoptosis-inducing ligand(TRAIL)can induce cardiomyocyte apoptosis,regulate macrophage migration,and promote the secretion of inflammatory cytokines when I/R occurs in the heart.We established TRAIL inhibitor sDR5-Fc protein in our laboratory,and our previous experiments suggested that sDR5-Fc can protect Wistar rats heart I/R injury,but the specific mechanism is not yet clear.Therefore,in this study,We first identified whether sDR5-Fc exerts cardioprotective effects through the regulation of macrophages and further explores the molecular mechanisms.PurposeThe role and mechanism of macrophage in the reduction of cardiac I/R injury by sDR5-Fc were initially revealed in vitro and in vivo experiments.MethodsIn vivo,Establish Wistar myocardial I/R injury model,macrophage infiltration in the heart and therapeutic effect were assessed by Immunohistochemistry;The expression of cardiac chemokines and their receptors was detected by qPCR;The deletion of macrophages in Wistar rats was verified via Clodronate Liposomes by flow cytometry;and the myocardial protective effect of sDR5-Fc was confirmed by TTC staining and immunohistochemistry in macrophages;In vitro study,Transwell system was used to detect The chemokinesis effect of TRAIL on NR8383 macrophage cell line and primary cell BMDM were detected by Transwell system.By establishing H/R model,the inflammatory factors,chemotactic factor and its receptor expression were detected by qPCR,these may prove the effect of sDR5-Fc via macrophage.ResultsAfter establishment of myocardial I/R in Wistar rats,we found macrophage infiltration increased in the myocardial tissue by immunohistochemistry;however,the infiltration obviously reduced and after used sDR5-Fc.Moreover,Macrophages in the heart of the chemokine and its receptor expression was significantly reduced.Then we deleted successfully by Flow Cytometry.on the basis of this,we established myocardial I/R in Wistar rats.The results showed that sDR5-Fc can protect myocardial tissue via macrophages by TTC.In addition,we induced macrophages chemotaxis by TRAIL and the chemotaxis improved after sDR5-Fc.Simultaneously,Macrophage chemotactic factor and its receptor as well as the inflammatory factors expression were decreased via qPCR in the H/R model.ConclusionsAbove experiments in vitro and vivo demonstrate that sDR5-Fc can relieve the inflammatory reaction of macrophages during myocardial I/R injury and play the role of myocardial protection.Moreover,This protective effect is achieved by inhibiting the activation of macrophages.