The Value Of Podocalyxin And Gd-IgA1 Levels In Urinary Exosomes For Diag Nosis Of Diabetic Kidney Disease And Immunoglobulin Nephropathy

Objective : Diabetic kidney disease(DKD)and immunoglobulin A nephropathy(IgAN)are common clinical glomerular diseases,and early diagnosis with identification for prognosis of the disease are important.Studies have found that proteins urinaryexosomes may reflect the pathophysiological process of kidney tissue,and podocalyxin(PCX)and Galactose-deficient IgA1(Gd-IgA1)may be specific molecular marker protein for DKD and IgAN,respectively.Because urinary exosomes can carry these two proteins,This study try to examine PCX and Gd-IgA1 levels in urinary exosomes in patients with DKD and IgAN;and the correlation between the leves of PCX and Gd-IgA1 in urinary exosomes with various indicators in DKD and IgAN was analyzed,and evaluate the value of detecting PCX and Gd-IgA1 levels in urinary exosomes for differential diagnosis beteween DKD and IgAN.The study may provide a reference for clinical identification of these two common glomerular diseases,especially for identification of DKD with IgAN.Methods:30 patients with type 2 diabetic kidney disease and 15 patients with Immunoglobulin A nephropathy who were admitted to the Department of Nephrology and Endocrinology in our hospital between October 2019 and October2020 were selected.The basic entry criteria is the baseline 24 hours of urinary protein ≥500mg.15 health persons for check-up in this hospital were enrolled as controls.Collect general data,including age,gender,height,weight,body mass index,systolic blood pressure,diastolic blood pressure and other general indicators.Automatic biochemical analyzer was used to detect total cholesterol,triglycerides,Fasting blood-glucose,glycated hemoglobin,blood Serum creatinine,Uric acid,Aspertate aminotransferase,Alanine aminotransferase,urea nitrogen and other conventional biochemical indicator levels and determine the determine the 24 hour urinary protein quantitative level.protein quantitative level.Urine exosomes were extracted by ultracentrifugation,and Western blot was used to identify specific marker proteins of urinary exosomes.The PCX and Gd-IgA1 levels protein in urinary exosomes extracted from subjects were detected using Enzyme-linked immunosorbent assay.Inaddition to the data that need special introduced,the other data are represented by mean ± standard deviation.All statistical analyses were analyzed by SPSS 20.0,P<0.05 indicates that the difference is statistically significant.Results:1.Western blot can show the positive bands of CD63,a marker protein on the surface of urinary exosomes extracted by ultracentrifugation.2.There were no significant differences among the three groups in gender,age,height,weight,BMI,SBP,DBP,FBG,Hb A1 c,UA,Scr,BUN,TC,TG,ALT,AST,CRP(P>0.05).3.There was significant difference between the DKD group and IgAN group with control group for 24 hour urinary protein level(1792.48±970.46mg/24 h VS78.18±31.11mg/24 h,P<0.05;1721.07±860.65mg/24 h VS 78.18±31.11mg/24 h,P<0.05).Butno difference for this parameter between DKD with IgAN group(1792.48±970.46mg/24 h VS 1721.07±860.65mg/24 h,P>0.05).4.The PCX levels of urinary exosomes in DKD group was significantly higher than those in the IgAN group and control group(0.38±0.06ng/ml VS0.27±0.05ng/ml,P<0.05;0.38±0.06ng/ml VS0.23±0.04ng/ml,P<0.05).However,there was no significant difference between the IgAN group and the control group(0.27±0.05ng/ml VS0.23±0.04ng/ml,P>0.05).5.The Gd-IgA1 levels of urinary exosomes in IgAN group was significantly higher than those in the DKD group and control group(2.20±0.08ng/ml VS 1.88±0.14ng/ml,P<0.05;2.20±0.08ng/ml VS1.79±0.16ng/ml,P<0.05).But there was no significant difference between the DKD group and control group(1.88±0.14ng/ml VS1.79±0.16ng/ml,P>0.05).6.Spearman correlation analysis revealed that the PCX levels of urinary exosomes was positively correlated with 24 h urinary protein levels in DKD group(r=0.51,P<0.05)and the Gd-IgA1 levels of urinary exosomes was positively correlated with 24 h urinary protein levels in IgAN group similarly(r=0.76,P<0.05).7.ROC analysis showed that the PCX in urinary exosomes had higher sensitivity and specificity for the diagnosis of DKD(AUCROC =0.92);the Gd-IgA1 in urinary exosomes had higher sensitivity and specificity for the diagnosis of IgAN(AUCROC=0.92).Conclusion:Urinary exosomes can be successfully isolated by ultracentrifugatio.The PCX levels in Urinary exosomes were significantly increased in DKD group,and those increases were consistent with the degree of glomerular injury.Comparably the Gd-IgA1 levels in Urinary exosomes were significantly increased in IgAN group,andt he elevated levels was consistent with the degrees of glomerular injury.Detection of the PCX and Gd-IgA1 levels may be an effective and noninvasive approach to identify DKD from IgAN.