Value of podocalyxin levels in urinary extracellular vesicles for diagnosis of diabetic nephropathy

Abstract

To explore the value of detecting podocalyxin (PCX) level in urinary extracellular vesicles for the diagnosis of diabetic nephropathy. This study was conducted among 57 diabetic patients admitted during the period from March to September, 2017, including 34 with uncomplicated diabetics and 23 with diabetic nephropathy; 21 patients with other types of nephropathy and 11 healthy individuals were also included to serve as the controls. Transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) were used to verify the separation of urinary extracellular vesicles. The molecular markers of extracellular vesicles (TSG101 and podocalyxin [PCX]) were detected using Western blotting. PCX levels in extracellular vesicles were also detected using ELISA. TEM reveal the presence of numerous extracellular vesicles in the urine with intact morphology and different sizes, and most of them were below 300 nm in diameter as shown by NTA. TSG101 expression was detected in the samples from all the 4 groups. Positive expression of PCX was detected in the samples from patients with diabetic nephropathy but not in the other groups. In patients with diabetic nephropathy, the mean PCX levels (3.27±2.30 ng/μmol)was significantly higher than those in the healthy control group (1.22±0.36 ng/μmol), uncomplicated diabetes group (2.22±1.29 ng/μmol) and nephropathy group (1.24±0.45 ng/μmol). PCX level in urinary extracellular vesicles is significantly increased in patients with diabetic nephropathy, suggesting the value of PCX as a potential marker for clinical diagnosis of diabetic nephropathy.