Express And Significance Of Ezrin And WT1 In Glomeruli Of Patients With Idiopathic Membranous Nephropathy

Objective: Idiopathic membranous nephropathy (IMN) re- mains the most common form of primary glomerulonephritis causing nephrotic syndrome in adults, and is characterized with two quite variable long-term outcome, complete spontaneous remission or progression to renal failure. It is sometimes resistant to immunosuppressive drugs resulting in longer course of treatment and more side effects. Therefore, it urges people to pay more attention to research prognosis factors and patho- genesis of IMN. On the basis of many clinical and laboratory studies, the accumulation of immune deposits under glomerular epithelial cell (GEC) is one character of IMN, as a disease induced by Immunological mechanism. Pathological changes of kidney focus on visceral glomerular epithelial cell (podocyte).Ezrin has been believed to as a kind of podocyte protein, and belongs to a family of plasma membrane-cytoskeleton linking proteins (ezrin, radixin, moesin family, ERM),during the last few years. ezrin involved in the interaction of the cell cytoskeleton with the plasma membrane, and played a key role in the control of cell morphology, signal transduction and growth. Moreover, ezrin was known as a marker for activated or damaged podocytes in experimental models. It was also reported that the expression of ezrin protein (by immunohistochemistry) was specifically and exclusively modulated during podocyte injury caused by different causes and pathogenesise.The human Wilms'tumor 1 gene (WT1), as a tumor sup- pressor gene, specially expressed in podocyte of the mature glomerulus. WT1 played a crucial role in the functions of the podocyte. Increasing evidence in wt1-null mice suggested that reduced expression levels of WT1 result in either crescentic glomerulonephritis or mesangial sclerosis depending on the gene dosage. Aslo, it was reported that the major podocyte protein nephrin was transcriptionally activated by WT1.The goal of our study is for investigating the expression of ezrin and WT1(by immunohistochemistry) in the glomeruli of patients with IMN, and their relationship to albuminuria and serum creatinine. Discuss the possible of ezrin or WT1 used as a Immunohistochemical marker for renal pathology of IMN, and further dissect the role of ezrin and WT1 in renal pathology and injured podocytes in order to provide a new idea and method in the clinic treatment and prognosis in IMN.Methods: (1) 25 cases of idiopathic membranous nephro- pathy group (IMN group) were collected from the patients who underwent renal biopsy in Department of Nephrology, the second hospital of Hebei Medical University, from December 2005 to December 2006. The 25 objects were divided into three groups: stageⅠIMN group (n=13), stageⅡIMN group(n=8), and stageⅢ+ⅣIMN group(n=4), according to their pathological stages of IMN. (2) 5 cases of control group were collected from the patients who were performed operations for removing benign tumor kidney in Department of Uropoiesis Surgery. (3) 24-hour urine samples and serum specimens were taken from all objects. (4) Immunohistochemistry was applied to detect the expression of ezrin and WT1 in renal glomerulus of patients with stageⅠIMN group, stageⅡIMN group, stageⅢ+ⅣIMN group and the control group. (5) The immunohistochemical expression of ezrin and WT1 were recorded by Expression Index(EI). (6) The estimates of ezrin and WT1 expression were mathematically analysed to examine changes of both markers in the various glomerulopathies and the 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. And correlation analysis was processed between immunohistochemical result and clinical index. Significance was set at P<0.05. (7) Use SPSS 10.0 statistical software to analyze the above-mentioned date.Results: (1) By immunohistochemistry, ezrin is expressed solely by parietal and visceral glomerular epithelial cells in glomeruli. The expression of ezrin in podocytes progressively reduced from the control group (10.79±1.85) to stageⅠIMN group(8.36±1.75) to stageⅡIMN group (5.61±1.64) to stageⅢ+ⅣIMN group (3.47±0.76). Significant differences were observed among all groups in the expression of ezrin in podocytes (P<0.05). (2) No statistically significant differences of WT1 expression in podocytes were found between both that of control group (9.42±4.38) andⅠstage IMN group (7.31±2.76) and stageⅡIMN group (9.25±4.02) (P>0.05),but WT1 expression in stageⅢ+ⅣIMN group (3.71±0.66) was obviously decreased as compared it with that of other groups(P<0.01). (3) The expression of ezrin was negatively correlated with 24h urine protein quantity(r=-0.615,P<0.01), and with serum creatinine(r = - 0.395 , P = 0.028), respectively. Otherwise, the correlation between expression of WT1 and 24h urine protein quantitation was not discovered. The similar situation was found between expression of WT1 and serum creatinineConclusions: (1) ezrin was Specifically expressed by GEC. The decreased expression of ezrin in podocyte was associated with the development of albuminuria and decreased-renal- function in IMN. (2) Moreover, the expression level of ezrin correlated with the histopathologic stages of IMN. ezrin could be used as a potent marker of podocyte injury and prognosis of IMN. (3) WT1 was able to mark podocyte accurately in IMN, but hardly reflected the severity of podocyte injury. The role of WT1 in IMN remains further research.