Effect Of Celecoxib On Peritoneal Function And Angiogenesis In Uremic Peritoneal Dialysis Rats

Background and ObjectiveEnd-stage renal disease(ESRD)has become one of the major diseases which effects human health in the21st century,the morbidity is increasing year by year.There are three main renal replacement therapy that are used in clinical practice including hemodialysis(HD)、peritoneal dialysis(PD)and kidney transplant.As the source of kidney is limited,and also campared with HD,PD have its own advantages:such as more simple and convenient operation,lower cost,lower risk of cross infection rates,better residual renal function protecting effect,smaller hemodynamic effect,etc.PD is becoming one of the most important replacement therapy gradually,and it is being accepted by more and more uremic patients.However,some complications often occur during PD procedure for a long time,for example:peritonitis,change of morphlogy and function,ultrafiltration failure(UFF),malnutrition and so on.Acroding to latest research,the incidence of UFF was as high as36%in ESRD patients who have maitained PD for more than4～5years,It has become the main reason for PD patients to withdraw from PD.The pathogenesisf of UFF mainly include peritoneum angiogenesis,peritoneum fibrosis_and the increasing of peritoneal interstitial/lymph fluid reabsorbing rate.Peritoneum angiogenesis has become a research hot spot.So,the mechanism and therapeutic method of peritoneum angiogenesis should be studied,which has a significance of improving the quality life of patients.Vascular endothelial growth factor(VEGF)is the most powerful promote vascular growth factors as we known which can induce angiogenesis.The levels of VEGF was significantly increased in PD patients and animals model.The biological effects of VEGF induce peritoneum angiogenesis in uraemic rats.there was negative correlation between VEGF and ultarfiltration capacity.Cyclooxygenase(COX-2)is a rate-limiting enzyme in the biosynthesis of prostaglandins from arachidonic acid.Three isoforms have been identified,so far:COX-1,COX-2,COX-3.COX-2,which is an inducible isoform whose expression can be increased by stimulation,such as cytokines,tumour promoters,growth factors.COX-2plays important roles in Tumor Angiogenesis.COX-2stimulate the expression of VEGF by its products of prostaglandin and thromboxane from arachidonic acid,which can increase vascular permeability and vascular flow,inhibit the apoptosis of endothelial cell,promote angiogenesis directly or indirectly.VEGF induces prostacyclins by increasing phopholipase-A2-mediated arachidonic acid release and up-regulates expression of COX-2.Researchs have show that the expression of COX-2and VEGF have positive relationship with Microvessel Density(MVD).Selected inhibitors can inhibit the expression of PGE2、PG12and VEGF.So the aim is to study the role and the mechanism of peritoneal angiogenesis and function in uremic PD rats and provide an effective therapy for multiple control the occurrence of UFF.Methods48male SD rats of clean grade were selected(180-200g),and they were divided into five groups randomly(mean=8):A:normal control group,B:sham operation group,C:uremia group(5/6nephrectomy),D:uremia PD group(4.25%PDsolution,D1:2weeks PD model,D2:4weeks PD model),E:uremic PD+celecoxib(irrigation of20mg/Kg BW).4.25%glucose dialysate at3ml/100g body weight was administered intraperitoneally to the rats.The rats from group D and E were given regular PD for4 weeks(D1for2weeks).The rats from group E accepted gastric perfusion of Celecoxib during PD every days.Before the rats were euthanized,they was given peritoneal equilibration test(PET),calculate the the mass transport of glucose and peritoneal ultrafiltration volume.Parietalperitoneum stained with HE and Masson stain.Immunohistochemical staining and RT-PCR were applied to detect the protein and mRNA expressions of COX-2,VEGF in omentum in each groups of rats.Microvessel density(MVD)of peritoneal tissue was used and quantified using immunohistochemical staining with anti-CD31antibody.Statistical analysis was performed to compare with their expressions and corelationship in each group.Significance was defined as a=0.05.Results1.Morphologic changes were assessed in tissue sections stained with HE and Masson stain in aimal models,4weeks animal model was obviously.Compared with normal group,peritoneal thickness and mass transport of glucose were increased obviously,and also ultrafiltration volume were decreased in PD group(all P<0.05);Compared with PD group,peritoneal thickness and mass transport of glucose were decreased obviously,and also ultrafiltration volume were increased in PD group(P<0.05).2.There was no significant difference of COX-2and VEGF expression both in protein and mRNA level between groupA and groupB.Compared with groupA,the protein and mRNA expression of COX-2and VEGF were significantly increased in groupC and groupD2(all P<0.05);Compared with groupC,the protein and mRNA expression of COX-2and VEGF were significantly increased in groupD2(P<0.05);Compared with group D2,the protein and mRNA expression of COX-2and VEGF were significantly decrease in groupE2(P<0.05).3.Only few new microvessel was found in groupA and groupB.There was no significant difference of MVD between groupA and groupB;Compared with groupA,MVD was significantly up-regulated in groupC and groupD2(all P<0.05);Compared with groupC,MVD was significantly up-regulated in groupC and D(P<0.05); Compared with groupD2,MVD was significantly down-regulated in groupE2(P<0.05)4.There was a positive correlation between VEGF and COX-2in protein and mRNA levels.And also there was a positive correlation between and VEGF,COX-2and MVD;COX-2,VEGF was related with angiogenesis.Conclusions1.The expression of COX-2,VEGF both in mRNA and protein level might be up-regulated by high glucose peritoneal dialysis liquid and uremic circumstance,and the high levels of COX-2,VEGF in uremic PD rats peritoneum might involve with the increasement of the peritoneum neoangiogensis and in the process of UFF.2.Celecoxib can improve the morphology and function of peritomeum.3.Celecoxib can inhibit peritoneum angiogensis in uremic PD rats.