The Machanism Research Of The Podocyte Injury In Diabetic Nephropathy Patients

Objective:To indicate the mechanism of podocyte injury in diabetic nephropathy (DN)patients by identifying the urinary podocytes and observe the expression of specific protein Podocalyxin(PCX) in glomeruli using indirect immunofluorescence. To address the clinical significance of the urinary podocytes for the DN patients.Methods:All the patients were collected from the hospitalized and out cases between 2005-2006, there were 50 pateints with diabetic mellitus (1997 ADA diagnosis standard), proteinuria and diabetic retin---opathy(DR), excluding the other renal diseases. 25 patients with min--imal change disease(MCD)who were all proved by the renal biopsy, 10 cases were healthy and orgnized as control. Morning urine(100ml) were collected and centrifuged, then the sediments were transfer to the glass slides. Urinary podocytes were identified by indirect immunofluorescent staining of podocyte specific protein(PCX). The 50 cases of DN patients were divided into three groups according to the proteinuria, namely small-volume-proteinuria(＜1G/D) 13 cases; middle-volume-proteinuria group (1-3.5 G/D) 21 cases and large-volume-proteinuria group(＞3.5 G/D) 16 cases. the data was analyzed statistcally.Meanwhile, the 24 hrs protein in urine, fasting blood glucose and the serum creatinine of 50 cases DN pateints were tested. The correlation between proteinuria, serum creatinine, fasting blood glucose and the number of positive podocytes in DN pateints was analyzed statistcally at the same time.The 50 cases of DN patients were divided into five groups according to the (NKF-K/DOQI) CKD, namely CKDIgroup (GFR＞90ml/min/1.73m~2)23 cases; CKDⅡgroup (GFR 60-89 ml/min/1.73m~2) 5 cases; CKDⅢgroup (GFR 30-59ml/min/1.73m~2)5 cases; CKDⅣgroup (GFR15-29ml/min/1.73m~2) 9 cases; CKDV group (GFR 0-14ml/min/1.73m~2) 8 cases. Then the numbers of positive podocytes in the groups of the patients urine were calculated respectivelly, the data was analyzed statistcally. From above 50 DN cases and 25 MCD cases, 12 cases who were diagnosed as DN or 12 MCD cases by routine renal biopsy were observed the PCX expression state of podocytes in glomeruli using indirect immunofluorescence.Results: Urinary podocytes were found in 88 percent of patients with DN, whereas 0 %of patients with MCD and 0 % in healthy casese. The numbers of PCX-positivepodocytes in different proteinuria groups of DN patientsshowed that the positive podocytes in small-volume-proteinuria group is 1. 49±0.95/HPF, middle-volume-proteinuria group2.15±0.70/HPF and large volume proteinuriagroup 3.48±1.27/HPF respectively. The difference from small and middle groups were not signifficent statistically, the others were all significant (P＜0.05).The positive podocytes numbers increased according to the protein--uria .Bypearson-correlation analysis,the calculated results were r=0.785, t_r=8.78; p＜0.05. the correlation between podocytes numbers and proteinuria was positive statistically.The numbers of PCX-positive podocytes in urine in groups of DN patients were: CKDⅠgroup2.30±1.49/HPF; CKDⅡgroup 2.96±0.71/HPF; CKDⅢgroup 4.00±1.32/HPF;CKDⅣgroup 2.20+1.71/HPF;CKDⅤgroup 1.09±0.92/HPF.The difference from different groups were not signifficent statistically (p＞0.05).The correlation between fasting blood glucose, serum creatinine and positive podocytes in urine were not significant via the pearson correlation analysis (p＞0.05).The absence of expression of PCX , a marker protein of podocytes in glomeruli was found in 12 cases of DN patients .The absence of the expression of PCX were consistent with the lesions of sclerosis in glomeruli. In contrast ,PCX was expressed integrally in 12 cases of MCD patients.Conclusion:We proofed the mechanism of the podocyte injury in DN patients Via the methods that detect the appearances of the podocytes in urine and the absence of the expression of PCX in glomeruii of the patients with DN. The podocyte injury in DN may positively correlate to the proteinuria ,and the serum creatinine and the fasting blood glucose may not correlate to the podocyte number in urine The test of podocytes in urine of patients with DN may be used as one of the convienent and safe accessorial methods to detect the progression of DN.