Celecoxib Prevents The Expression Of STAT3,COX-2and VEGF In Experimental Choroidal Neovascularization

Objective:Choroidal neovascularization commonly combine withmany disorders.It is the pathologic neovascularization of choroid whichinvade subretinal space or under RPE.CNV is one of the leading causes ofsevere visual loss in the world.And it become challence of ophthalmology.Celecoxib is a kind of ordinary non-steroid anti-inflammatory drugswhich is a highly selective cyclooxygenase-2inhibitor.Studies have foundthat it is effective to inhibit choroidal neovascularization(CNV). Signaltransducer and activator of transcription3,STAT3takes part in thedevelopment of tumor and ocular neovascularization.This study isdesigned to approach the mechanism of CNV and the effect ofcyclooxygenase-2(COX-2) inhibitor celecoxib on the experimental CNVmodel induced by laser photocoagulation through observe the expressionof phosphorylated signal transduction and activator of transcription3(STAT3)and the effect of COX-2inhibitor celecoxib on the expressionof phosphorylated STAT3, COX-2and vascular endothelial growthfactor (VEGF) in the model.Methods:1The study of experimental CNV model1.110healthy male(Brown Norway)BN rats (one experimental eye andone control eye per rat)were received a series of9Krypon laster (647nmwave length,50μm spot size,360mW power,0.05second duration)lesions around the optic nerve head per experimental eye.1.2Fundus fluorescein angiography (FFA) was performed on days1,3,7,14,21after laser photocoagulation.1.3The rats were sacrificed6h later.Histopathologic examination for the relative thickness of CNV.1.4Statistical analysis was performed by Chi-square tests andNonparametric Test by SPSS13.0.2The expression of STAT3in CNV membranes of the experimental CNVmodel2.1Laser photocoagulation was performed on12healthy male(BrownNorway)BN rats (one experimental eye and one control eye per rat). Theexpression level of STAT3mRNA was detected by real-time PCR.2.2Imunohistochemistry for Phosphorylated STAT31day,3days,7daysand14days after laser photocoagulation.The retinal sections were gotfrom the first part. CMIS-2011image analysis system was used to detectresult.2.3Statistical analysis was performed by one-way ANOVA,test fordistribution of normal and t-test by SPSS13.0.3The study of celecoxib inhibits the expression of STAT3,COX-2,VEGF in the experimental model of CNV.3.115healthy male(Brown Norway)BN rats were randomly divided intothe blank control,laser control and celecoxib treated group,with3rats inthe blank control group and6rats for the rest groups each.Rats incelecoxib treated group gavaged celecoxib twice per day at the dosage of50mg/kg (till the end of the experiment).One week later,experimentalCNV was induced by Krypon laser on laser control group and celecoxibtreated group (one experimental eye and one control eye per rat).3.2On days3,7,21after laser photocoagulation, fundus fluoresceinangiography(FFA) was performed to observe the incidence of CNV.3.3Histopathologic examination for the relative thickness of CNVmembranes3.4Immunohistochemistry examination for the expression ofphosphorylated STAT3, COX-2and VEGF.3.5Statistical analysis was performed by Chi-square tests and t-test bySPSS13.0 Results:1The study of experimental CNV model1.1CNV firstly appeared on day7after laser photocoagulation and theincidence of CNV peaked on day21(13/18,72.22%)(χ~2=118.389,P＜0.01)1.2FFA showed hyperfluorescence in the early stage and fluorescenceleakage in the late stage.1.3It was showed by light microscope that CNV invade the subretinaspace through Bruch's membrane and macrophage,RPE and fibroblastinfiltrating in the CNV area.Early CNV can be seen7days afterphotocoagulation. proliferation of CNV and new vessels can be seen21days after photocoagulation.1.4The relative thickness of CNV increased on days7-21afterphotocoagulation and reached the peak on day21.(χ~2=23.484,P＜0.05)2The expression of STAT3in CNV membranes of the experimental CNVmodel2.1STAT3mRNA expressed highly in CNV area3days after laserphotocoagulation according to the analyses of the RT-PCR (F=36.503,p＜0.01).2.2Phosphorylated STAT3expressed highly in CNV area3days afterlaser photocoagulation according to the analyses of theimmunohistochemistry(F=111.629,P＜0.01).3The study of celecoxib inhibits the expression of STAT3,COX-2,VEGF in the experimental model of CNV.3.1The incidence of CNV in the celecoxib treated group weresignificantly lower than that in the laser group on days7,21after laserphotocoagulation (χ~2=9.036,10.923P＜0.01,P＜0.01).3.2The relative thickness of CNV in the celecoxib treated group wereevidently lower than that in the laser group on days7,21after laserphotocoagulation(t=2.730,4.962P＜0.05,P＜0.01)3.3According to the analyses of the immunohistochemistry the expression of phosphorylated STAT3in the celecoxib treated group weresignificantly lower than that in the laser group on days3,7after laserphotocoagulation (t=﹣7.834,﹣3.547P＜0.01,P＜0.01)and nodifference on day21(t=0.101P=0.921). The expression of COX-2andVEGF were suppressed obviously in the celecoxib treated group ondays7,21after laser photocoagulation (t=﹣3.872,﹣10.905,﹣3.608,﹣4.284P＜0.01,＜0.01,＜0.01,＜0.01)and no difference on day3(t=﹣2.042,﹣1.972P=0.056,0.064). The expression ofphosphorylated STAT3, COX-2and VEGF in the blank control groupwere weak.Conclusion:1STAT3may be involved in early CNV formation.STAT3may implicatein transcription regulation of COX-2, VEGF and promote thedevelopment of CNV.2Cyclooxygenase-2(COX-2) inhibitor celecoxib can suppress theformation of CNV efficiently.This maybe depend on the reduction ofthe expression of COX-2and VEGF which are regulated by STAT3.