Expression of synaptopodin and WT-1 in renal tissue of patients with diabetic nephropathy

Abstract

Objective To explore the effects of synaptopodin and WT-1 expression on the progression of diabetic nephropathy. Methods Thirty-five renal specimens of patients with confirmed diabetic nephropathy from January 1998 to September 2005 were selected and divided into the diffuse mesangial sclerosis group (n=20)or the nodular sclerosis group(n=15). Para-carcinoma tissues of 7 patients with renal carcinoma were regarded as controls. The expressions of synaptopodin and WT-1 in renal tissues of patients with diabetic nephropathy were detected by indirect immunofluorescence double-staining and confocal laser scanning microscope, which were analyzed by one-way ANOVA and q test. Clinical data of patients before renal biopsy were collected, including total urine protein for 24 hours (TUPr), serum creatinine (Scr) and evaluated glomerular filtration rate (eGFR), followed by analyzing with t test. Correlations between immunopathological and clinical indexes were analyzed by linear correlation. Results Compared with the diffuse mesangial sclerosis group, TUPr and SCr levels were elevated (TUPr: (3.7±0.9) or (5.6±1.6) g/24 h, t=4.177, P<0.05; SCr: (92±20) or (135±45) μmol/L, t=10.455, P<0.05), and eGFR was decreased in the nodular sclerosis group ((65±19) or (53±24) ml/min, t=8.921, P<0.05). Compared with the normal controls, the number of podocytes (F=4.06, P<0.05), the expressions of synaptopodin (F=3.79, P<0.05) and WT-1 (F=5.68, P<0.05) in patients with diabetic nephropathy were significantly decreased, which were more severe in the nodular sclerotic group than in the diffuse mesangial sclerotic group (q values were 5.80, 6.42, and 5.35, respectively; all P<0.05). In diabetic nephropathy, the expressions of synaptopodin and WT-1 had a negative correlation with TUPr (r=-0.64 and -0.71, respectively; both P<0.05), and a positive correlation with eGFR (r=0.57 and 0.62, respectively; both P<0.05). Conclusion The expressions of synaptopodin and WT-1 are decreased in gelomeruli of patients with diabetic nephropathy, which correlated with clinical indexes of renal impairment. Those findings suggest that podocyte injury may be involved in the progression of diabetic nephropathy. Key words: Diabetic nephropathy; Podocytes; Proteinuria