Expression Of Elabela In Serum Of Peritoneal Dialysis Patients And Its Clinical Significance

Objective:To detect the changes of serum Elabela（ELA）and Apelin（APLN）levels in patients with chronic kidney disease stage 5（CKD5）without dialysis and peritoneal dialysis（PD）of different dialysis duration.To explore the differences and causes of serum ELA and APLN levels among the three groups: CKD 5 without dialysis,PD dialysis duration < 36 months（PD<36 group）,and PD dialysis duration ≥ 36 months（PD≥36 group）.To explore the protective effect of ELA on epithelial-mesenchymal transformation（EMT）of human peritoneal mesothelial cells（HPMC,HMrSv5）induced by transforming growth factor-β1（TGF-β1）in vitro.Methods:Part Ⅰ: The fasting serum of patients with CKD5 and PD diagnosed in the Department of Nephrology of the second Hospital of Jilin University from September2020 to September 2021 were collected.Collect clinical indicators（age,sex,body mass index,primary disease,whether complicated with hypertension,diabetes,laboratory indicators,peritoneal balance test,dialysis adequacy）.Human ELA and APLN Elisa kits were used to determine the levels of ELA and APLN in human serum.Correlation analysis and multiple linear regression were used to analyze the correlation between serum ELA,APLN,and the above clinical indexes.Part Ⅱ: In vitro experiment: HMrSv5 cells were stimulated by TGF-β1 10ng/m L to establish the EMT model,and the treatment group was given ELA-32 peptide（10μM）combined with TGF-β1（10ng/m L）for 24 h,the expression of E-cadherin,α-SMA,fibronectin,and vimentin was detected by Western Blot,the ability of cell migration was detected by wounding heal assay and Transwell assay,and the expression of E-cadherin,α-SMA,and fibronectin was observed by immunofluorescence.Results:1.The fasting serum of 80 patients was collected,including 20 patients in CKD5 without dialysis,40 patients in the PD<36 group,and 20 patients in the PD≥36 group.The results showed that the serum ELA level of CKD5 patients was 44.92±12.61ng/m L.The serum content of PD<36 group increased significantly（66.95±24.73ng/m L）（P<0.05）,while there was no significant statistical difference in the PD≥36group（47.14±14.34 ng/m L）.2.The age,sex,hypertension,diabetes,and primary disease of patients in CKD5 without dialysis,PD<36,and PD≥36 groups were compared.There was no significant difference among the three groups.The dialysis duration of the PD<36 group was9.00（3.25,18.75）months,and that of the PD≥36 group was 49.50（37.25,70.50）months,the difference was statistically significant（P<0.05）.Compared with the CKD5 group without dialysis,the contents of hemoglobin,residual glomerular filtration rate,carbon dioxide binding ability,and C-reactive protein in the PD < 36 group were increased（P< 0.05）.Compared with the PD<36 group,the 24 h urine volume,hemoglobin,and residual renal function of the PD≥36 group decreased（P <0.05）,and there was no statistical difference in other clinical indicators such as peritoneal balance test（P>0.05）.The correlation analysis of the above clinical indicators with serum ELA and APLN levels showed that there was a negative correlation between serum ELA and age of dialysis（r=-0.525,P<0.05）,and a positive correlation between glomerular filtration rate（r=0.321,P<0.05）in PD patients.Serum APLN was positively correlated with the dialysis duration（r=0.355,P<0.05）.Further multiple linear regression analysis suggested that the main risk factor influencing the decline of serum ELA level in PD patients was the dialysis duration（r=-0.436,P<0.05）.3.The results of HMrSv5 in vitro experiments suggested that ELA-32（10μM）could reduce the morphological changes of HMrSv5 cells induced by TGF-β1.Western Blot and immunofluorescence showed that ELA-32 could decrease the expression of fibronectin,α-SMA,and vimentin induced by TGF-β1,and restore the expression of epithelial cell marker protein E-cadherin.Wounding heal assay and Transwell assay showed that ELA-32 inhibited the migration of HMrSv5 induced by TGF-β1.Conclusion:1.As CKD5 patients enter the early stage of PD,the serum ELA level increases,and the serum APLN level decreases.With the extension of dialysis duration,the serum ELA decreases to the pre-dialysis level,and the serum APLN level increases to the pre-dialysis level.2.In PD patients,the risk factor influencing the decline of serum ELA level was dialysis duration.3.In PD patients,serum APLN level was positively correlated with the dialysis duration.4.ELA-32 peptide can reduce TGF-β1-induced EMT of HMrSv5.