Correlation Between Peritoneal CD105 Expression And Peritoneal Ultrafiltration In Patients With Peritoneal Dialysis

Background:In recent years,the prevalence of chronic kidney disease(CKD)has been increasing year by year.According to incomplete statistics,the prevalence of CKD among adults in the world has reached 14.3%,and the prevalence of CKD among adults in China is about 11%.If CKD is not diagnosed and treated effectively,it will further develop into end-stage renal disease(ESRD),brings a heavy burden to society.At present,statistics show that the number of ESRD patients in China is as high as 3 million,and there are about 700,000 patients receiving dialysis,of which ESRD patients who choose peritoneal dialysis(PD)treatment account for about 11%of the total dialysis patients.Peritoneal dialysis is chosen by more and more ESRD patients because of its multiple advantages such as maintaining hemodynamic stability,protecting residual renal function,and being convenient,simple,and easy to operate.However,long-term exposure of the peritoneum of peritoneal dialysis patients to bioincompatible dialysis solutions and the chronic aseptic inflammatory state can lead to massive accumulation of peritoneal extracellular matrix(ECM),epithelial-mesenchymal transition(EMT)and peritoneal fibrosis(PF).The hypoxic state of the peritoneal cavity can further aggravate peritoneal angiogenesis,decreased peritoneal function,and eventually lead to peritoneal ultrafiltration failure(UF).CD 105(endoglin,ENG)is a transforming growth factor(TGF)binding protein and can be divided into two subtypes,L-CD105(Long-CD105)and S-CD105(Short-CD105).It will exist in plasma and urine in soluble form s-CD 105(soluble-CD105).CD 105 is expressed on the surface of endothelial cells and also in cells such as cardiac fibroblasts,skin fibroblasts,kidney fibroblasts,hepatic stellate cells and portal fibroblasts.During angiogenesis,CD 105 can regulate endothelial cell proliferation and angiogenesis,and can be used as a marker for tumor angiogenesis such as liver cancer,renal cancer,and choriocarcinoma,and is closely related to tumor metastasis and invasion.During fibrosis,in models of cardiac fibrosis,myocardial infarction,liver fibrosis,and skin fibrosis,CD 105 promotes the production of extracellular matrix proteins that promote fibrosis;However,in a mouse model of renal fibrosis with unilateral ureteral obstruction,it was found that overexpression of L-CD105 increased renal fibrosis,but overexpression of S-CD105 decreased renal fibrosis and inflammation,and this differential regulation was cell-specific,suggesting that the regulation of fibrosis by CD 105 may be based on the balance of the two isoforms of L-CD105 and S-CD105 in different stimuli and different types of cells and the different regulation of the downstream signaling pathways of TGF-β.The relevant role of CD 105 in peritoneal fibrosis has not been reported.This experiment aims to explore the correlation of CD 105 expression changes with peritoneal fibrosis and ultrafiltration function in peritoneal dialysis patients,and its potential role in peritoneal ultrafiltration failure in peritoneal dialysis patients is prospected.Part I To explore the changes of peritoneal morphological structure and transport function with the prolongation of peritoneal dialysis time.Objective:1.To clarify the changes of peritoneal morphological structure in patients with short-course dialysis and PD ultrafiltration failure compared with initial dialysis(control group).2.To clarify the changes of peritoneal transport function in patients with short-course dialysis and PD ultrafiltration failure compared with initial dialysis(control group).Methods:1.Sampling of peritoneal tissue:the initial dialysis patients who entered peritoneal dialysis for the first time were selected as the control group,and recorded as 0 day;the patients who had undergone short-course dialysis for reasons such as hernia,pleural fistula,and kidney transplantation within two years were selected as the short-course dialysis group,and recorded as<2years;the patients who had been on maintenance peritoneal dialysis for six years or more and finally quit peritoneal dialysis due to ultrafiltration failure were the PD ultrafiltration failure group,recorded as≥6years.2.MASSON and HE staining were used to observe the changes of peritoneal morphological structure of patients.3.Collect the clinical data,peritoneal balance test and ultrafiltration volume results of inpatient peritoneal dialysis patients in the Department of Nephrology of Shandong Provincial Hospital from 2013 to 2021(the result of the first peritoneal balance test one month after intubation were selected for patients with initial dialysis,and the last result before dialysis tube removal were selected for patients with short-course dialysis and PD ultrafiltration failure).4.Statistical analysis of the three groups of patients’ clinical data,peritoneal morphological changes,peritoneal balance test and ultrafiltration results.Results:1.Compared with the Oday group,the<2years group PD patients had thicker peritoneum and increased collagen fibers(P<0.05);Compared with the<2years group and the Oday group,the peritoneum of PD patients in the>6years group had the most obvious thickening and the most significant increase in collagen fibers(P<0.05).2.There was no significant difference in age and gender between the three groups(P>0.05).The ratio of 4-hour dialysate creatinine to blood creatinine(D/P Cr)in the three groups and ultrafiltration volume were statistically different(P<0.0001).Compared with D/P Cr(0.64±0.05)in Oday group,D/P Cr(0.73±0.07)in PD patients in<2years group increased,and D/P Cr in ≥6years group(0.83±0.04)increased more significantly than that in<2years group.Compared with the ultrafiltration volume of the Oday group(858.33±90.03),the ultrafiltration volume of the PD patients in the<2years group(694.12±117.10)decreased,and the ultrafiltration volume of the PD patients in the>6years group(60.48±33.98)decreased more significantly than that in the<2years group.Conclusions:1.With the prolongation of dialysis time,the peritoneum of PD patients gradually thickened,and the peritoneal fibrosis gradually increased.2.With the prolongation of dialysis time,the peritoneal fibrosis of PD patients gradually increased,and the peritoneal ultrafiltration function gradually decreased.Part Ⅱ Study on the correlation between peritoneal CD105 expression and peritoneal fibrosis,angiogenesis and peritoneal transport function.Objective:1.To clarify the expression changes of CD105 and fibrosis indexes in peritoneal tissue of patients with initial dialysis,short-course dialysis and PD ultrafiltration failure,and the correlation between CD 105 expression and fibrosis indexes expression was analyzed.2.To clarify the expression changes of.CD 105 and angiogenesis indexes in the peritoneal tissue of patients with initial dialysis,short-course dialysis and PD ultrafiltration failure,and analyze the correlation between the expression of CD 105 and the expression of angiogenesis indexes.3.To analyze the correlation between the expression of CD105 and peritoneal transport function.Methods:1.Western Blot was used to detect the changes of CD 105,fibrosis-related factor TGF-β,mesenchymal cell-like phenotype markers α-SMA,N-cadherin,Vimentin,epithelial marker E-cadherin,vascular endothelial growth factor A in the peritoneal tissue of the three groups.2.The expression levels of CD105,fibrosis-related factor TGF-β,mesenchymal cell-like phenotype markers a-SMA and VEGFA in the peritoneal tissue of the three groups of patients were detected by immunohistochemistry.3.RT-PCR was used to detect the expression of CD105 and VEGFA mRNA in peritoneal tissue of three groups of patients.4.According to the results of Western Blot and RT-PCR,the correlation analysis of CD 105 and the expression of TGF-β,α-SMA,N-cadherin,Vimentin,E-cadherin and VEGFA was carried out.5.According to the immunohistochemical staining of CD 105 and VEGFA in the three groups,the micro vessel density(MVD)of CD 105 and VEGFA was calculated,and the correlation between the two was statistically analyzed.6.According to the results of Western Blot,RT-PCR and MVD,the correlation analysis was made between the expression of CD 105 and 4h D/P Cr value and ultrafiltration amount.Results:1.Western Blot results showed that compared with Oday group,the expressions of CD 105,TGF-β,α-SMA,N-cadherin,Vimentin,and VEGFA in patients in<2years group were significantly increased(P<0.05),the expression of E-cadherin was significantly decreased(P<0.05);Compared with the<2years group,the expression of the increased indexes in the>6years group was more significantly(P<0.05),and the expression of E-cadherin decreased more significantly(P<0.05).2.Immunohistochemical results showed that compared with Oday group,the expressions of CD 105,TGF-β,α-SMA and VEGFA in the<2years group showed an upward trend(P<0.05);≥6years group compared with the<2years group,the upward trend of the above indicators was more obvious(P<0.05).3.RT-PCR experiment found that compared with Oday group,the expression of CD 105 and VEGFA in<2years group was significantly increased(P<0.05);≥6years group was significantly higher than that in<2years(P<0.05).4.At the protein level,the expression of CD 105 was significantly positively correlated with the expression of TGF-β(r=0.8879 P<0.0001),α-SMA(r=0.8330,P<0.0001),N-cadherin(r=0.8464,P<0.0001),Vimentin(r=0.8216,P<0.0001)and VEGFA(r=0.8072,P<0.0001),and was significantly negatively correlated with the expression of E-cadherin(r=-0.6407,P<0.0001).At the mRNA level,the expression of CD 105 was positively correlated with the expression of VEGFA(r=0.8608,P<0.0001).5.Compared with Oday group,the micro vessel density of CD 105 and VEGFA in<2years group showed an increasing trend(P<0.05);The micro vessel density of CD 105 and VEGFA increased more significantly in the>6years group than in the<2years group(P<0.05).CD105 was significantly correlated with MVD of VEGFA(r=0.8627,P<0.0001).6.The expression of CD 105 at the protein level(r=0.6464,P=0.0001),mRNA level(r=0.6945,P<0.0001)and MVD(r=0.7297,P<0.0001)were all showed significant positive correlation with 4h D/P Cr value;The expression of CD 105 at the protein level(r=-0.7756,P<0.0001),mRNA level(r=-0.8299,P<0.0001),and MVD(r=-0.9176,P<0.0001)were all showed significant negative correlation with ultrafiltration capacity.Conclusions:1.CD105 plays a role in promoting the development of peritoneal fibrosis.2.CD105 plays a role in promoting peritoneal angiogenesis.Increased expression of CD 105 can lead to significantly increased peritoneal angiogenesis.3.Elevated CD 105 expression led to ultrafiltration failure through peritoneal fibrosis and angiogenesis.