| Background and objectiveIschemic heart disease and myocardial infarction are a major cause of death in cardiovascular disease,usually due to acute thrombotic occlusion of coronary artery.In the process of myocardial ischemia reperfusion,a variety of media,such as nitric oxide,endothelin,adenosine,produced by heart,are considered to regulate myocardial I/R injury.During the process of ischemia-reperfusion injury,the expression of cyclooxygenase increased and caused the formation of prostaglandin.In vitro experiments and animal models of ischemia-reperfusion injury showed that prostaglandins could protect heart.However,the effects of endogenous PGE on ischemia-reperfusion injury are not clear.Therefore this study aims to explore the effect and mechanism of prostaglandin E on myocardial ischemia-reperfusion injury in mice.MethodsExperiment was divided into two parts.Part one was about microarray data analysis.Samples were collected from mice and human.We collected heart samples from mice after sham,IR,MI operation,as well as blood samples from PCI patients with different time points(T0,acute myocardial infarction before PCI;T1,day 1 after PCI;T4,day 4 after PCI).We did mRNA expression profile analysis,screened differential expressed genes,then found differences gene associated with prostaglandin synthesis pathway.Finally we used bioinformatics methods to forecast the genetic variations.Part two was about animal experiment.We selected different gene knockout mice,including cyclooxygenase 1(COX1)knockout mice,COX2 knockout mice,membrane associated prostaglandin E synthase-1(mPGES-1)knockout mice,as well as endothelial PGE receptor EP4 knockout mice,by building I/R model,to analyze the change of myocardial infarction area 24 hours after ischemia-reperfusion.We also did bone marrow transplantation on mPGES-1,and tried to explore the effect on blood and tissue structure of mPGES-1 in ischemia-reperfusion injury.After I/R experiment,we collected mice plasma 24 hours after reperfusion and analyzed the content of prostaglandins(PGE,PGI,TXB2)in plasma by mass spectrum.In addition,through the extraction of the abdominal granulocyte in mice,we conducted the in vitro experiment and observed the content of prostaglandins by inflammatory stimulation.ResultsAccording to the results of microarray data analysis in mice samples,compared with the sham group,the expression of COX2 in IR group significantly increased.The expression of PGI and PGE synthetase and TXA2 receptor in MI group significantly increased when compared with the sham group,while prostaglandin synthesis reductase significantly lowered.Compared with IR group,PGI and PGE synthetase and TXA2 receptor significantly increased in MI group.Human samples showed that compared with T4 group,the expression of COX2 in TO group significantly increased.Microarray results suggest that prostaglandin pathways were involved in the process of myocardial infarction.Animal experiment results showed that compared with wild type mice,COX1 knockout mice had larger myocardial infarction size,while COX2 KO mice had no significant difference of myocardial infarction size.And in the use of celecoxib,the myocardial infarction size of COX1 KO mice is still greater than that of wild type mice.So compared with COX2,COX1 has more protective effect on myocardial I/R injury.The infarction area of mPGES-1 knockout mice was greater than that of control group after I/R.And both blood phase and organizational structure will affect myocardial infarction area and the organizational structure of mPGES has greater effect on heart function.Mice lack of Endothelial EP4 receptors has greater infarction area than that of wild-type mice.By mass spectrum detection of blood samples,PGE in COX1 KO mice dropped significantly than WT mice.In mPGES-1 KO mice,PGE declined while PGI increased.After in vitro stimulation,granulocyte from WT mice produced more PGE and TXB2 but had less influence on PGI.PGI,PGE,TXB2 produced by COX1 KO mice granulocyte were significantly less than that of WT mice.After C5a stimulation,WT mice granulocyte produced more PGE than mPGES-1 knockout mice.ConclusionProstaglandin signaling pathways in MI has differential gene expression.Prostaglandin E showed protective effect on IR injury through COX1/mPGES-1/endothelial EP4 receptors signaling pathway.Background and objectiveMisoprostol is a kind of anti peptic ulcer drug,widely used in gastritis and ulcer disease caused by non steroidal anti-inflammatory drugs.It maintains the integrity of the gastric mucosa by increasing the level of prostaglandin E,which has a protective effect on cells.Misoprostol can increase the production of cyclic adenosine monophosphate(cAMP)combined with PGE receptor(EP2,EP3,EP4).Misoprostol regulates the expression of inflammatory cytokines through cAMP pathway.Myocardial ischemia/reperfusion injury is a series of pathophysiological processes,including inflammatory reaction,oxygen free radical and so on.Based on previous studies demonstrating the protective effect of misoprostol on cerebral ischemia and reperfusion,the role of misoprostol in cardiac I/R injury has not been studied.Therefore,the purpose of this study is to investigate the effects and mechanisms of misoprostol on ischemia-reperfusion injury in mice.Methods8-10 weeks male C57BL/6 mice were randomly divided into control group and misoprostol group.Using IR injury model(ischemia 30 min,reperfusion 24h),we detected myocardial infarction size 24h after reperfusion by TTC and Evans blue staining method.Hearts were digested by protease and collagenase,then inflammatory cells were detected by FACS.In addition,using RT-PCR to detect some marker expression in myocardial cells.Myeloperoxidase positive cells were detected in heart tissues by immunofluorescence.We asol did in vitro experiments,using FACS to analyze the expression of CD11b in white blood cells after LPS stimulation.ResultsBy injecting mice with different doses of misoprostol(50 ug/kg,100 ug/kg),we found that giving 50ug/kg dose of misoprostol had no effect on myocardial infarction area,while giving 100 ug/kg dose of misoprostol,infarction size was significantly smaller than that of control group.Then using flow cytometry technique we found that the number and percentage of infiltrates granulocyte in misoprostol group were significantly less than that of control group.Endothelial cell adhesion molecules expression and inflammatory response are closely related,so we detected the endothelial cell adhesion molecules mRNA expression level after IR injury.The results showed that misoprostol could significantly decrease P-selectin,Icam-1,Vcam-lexpressiom level after I/R.The number of MPO positive cells in misoprostol group was significantly less than the control group.Then we found that in vitro misoprostol can reduce the expression of neutrophils CD11b after inflammatory stimulation.ConclusionMisoprostol protects against myocardial ischemia/reperfusion injury via reducing inflammation. |
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