| Objective: Nephrotic syndrome (NS) manifests itself in massive proteinuria, hypoalbuminemia, edema, and hyperlipidemia. The integrated structure and function of the slit diaphragm is particularly critical for the occurrence of proteinuria. In recent years, many molecules related to slit diaphragm were found—nephrin, CD2AP, podocin, Wilms'tumor 1 (Wt1) and so on. Our study is to investigate the expression and distribution of nephrin and WT1 (by immunohistochemistry) in the glomeruli of patients with primary nephrotic syndrome, and to carry out the relative researches with trial index commonly used in clinical medicine (such as albuminuria with ration in 24h and plasma creatinine), so as to discuss the possible effect of nephrin and WT1 in the occurrence of proteinuria.Methods: Step 1: We selected 80 patients as the cases (50 men, 30 women), who conformed to the criterion of primary nephrotic syndrome (24h urine protein>3.5g, plasma albumin<30g/L). They are divided into four groups : 1. Minimal change nephropathy (MCN) (15 men and 5 women); 2. IgA nephropathy (IgAN) (13 men and 7 women, 11 mild mesangial proliferative cases, 8 focal proliferative sclerosing cases, 2 severe mesangial proliferative cases); 3. Membranous nephropathy (MN) (12 men and 8 women, 18 Stage I MN cases, 2 Stage II MN); 4. Focal segmental glomerulosclerosis (FSGS) (10 men and 10 women, 16 non-special-type fsgs cases, 2 top-type fsgs cases, 2 umbilical-type fsgs cases). Step 2: 10 cases (5 men and 5 women) were collected from the patients who were performed operations for removing benign tumor kidney in Department of Uropoiesis Surgery. Step 3: Immunohistochemistry was applied to detect the Expression Index (EI) for nephrin and WT1 in renal glomerulus of nephrotic syndrome patients and the control group. Also comparations were made between those four groups and the control group. Step 4: Correlation analysis was processed between immunohistochemical result and clinical index. Step 5: The estimates of nephrin and WT1 expression were mathematically analysed to examine changes of both markers in the various glomerulopathies. And differences between groups were evaluated by one-way analysis of variance test. To determine the significance between group means in the analysis of variance, the nearest significant difference test (SNK-q test) was used as the multiple comparison test. Step 6: SPSS 16.0 statistical software is used to analyze the above-mentioned data, in which process the significance was set at p<0.05. Results:1.By immunohistochemistry, nephrin was specifically expressed by glomerular epithelial cells (GEC). In control group, the distribution of nephrin showed an even and linear pattern along the glomerular basement membrane. In nephrotic syndrome group, the distributions of nephrin showed granular pattern. Staining in some regions apparently decreased and the linear pattern disappeared in some regions. The EI for nephrin expression in the control group is 14.65±3.53, MCN group 12.83±3.39, IgA group 11.70±4.13, MN group 11.92±3.84, and FSGS group 13.86±2.85. The expression of MN group and IgA group decreased significantly compared with that of the control group (p<0.05).2. In all groups WT1 expressed in the podocyte nucleus and cytoplasm. The EI for WT1 expression in the control group is 3.51±0.51, MCN group 2.54±0.85, IgA group 2.45±0.57, MN group 3.71±1.08, and FSGS group 1.93±0.31. WT1 expressions of MCN group, IgA group and FSGS group decreased significantly compared with that of the control group (p<0.05). And there are no big differences between MN group and the control group ( p>0.05).3. The expressions of nephrin and WT1 were negatively correlated with 24h urine protein quantitation. No relationship was found between their expressions and serum creatinine.Conclusions:1. Nephrin was specifically expressed by glomerular GEC. In control group, the distribution of nephrin showed a linear pattern along the glomerular basement membrane. In nephrotic syndrome group, the distribution of nephrin showed granular pattern. Staining in some regions apparently decreased and the linear pattern disappeared in some regions. The expression of MN group and IgA group decreased greatly compared with that of the control group. The decreased expression of nephrin was negatively associated with the development of urine protein. The expression of nephrin was positively correlated with plasma alb.2. WT1 expressed in the podocyte nucleus and cytoplasm. The expressions of MCN group, IgA group and FSGS group decreased compared with that of the control group. The expression of WT1 was negatively correlated with 24h urine protein quantitation and positively correlated with plasma alb.
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