Aims and method: Idiopathic membranous nephropathy (IMN) is the most common cause of nephrotic syndrome in adults worldwide. Many patients with IMN are elderly, but little is known about the relationship regarding the morphological stage determined by electron microscopy (EM), the amount of proteinuria, and the expression of glomerular podocyte markers such as desmin and nephrin in nephrotic glomeruli in IMN. We studied 59 patients with histopathologically proven MTN. We compared the clinical features, EM stage classification, and the immunohistochemical features of glomerular expression of podocyte markers, including desmin and nephrin, between older (age ! 60 years) and younger (age < 60 years) patients. We also investigated these parameters in patients with minimal-change nephrotic syndrome (MCNS), minor glomerular abnormalities (MGA), and normal kidneys as agematched controls. Results: Prevalence of nephrotic syndrome was significantly higher in the older (52.9%) than the younger group (20.0%) of IMN. The level of proteinuria was higher in early stages (Stages I + II) than in late stages (Stages III + IV) in IMN. The glomerular expression of desmin in podocytes was significantly higher in IMN as compared to MCNS, MGA, or age-matched controls. Desmin expression was significantly increased in earlier EM stages (Stages I + 11) and in higher proteinuric group (daily proteinuria >= 1 g) of older patients with IMN. Reciprocally, the reduced expression of nephrin was associated with the early EM stages (Stages I + 11) of patients with IMN. Conclusions: We conclude that the expression of desmin in podocytes is upregulated in patients with IMN as compared to other glomerular diseases including MCNS or MGA, or to controls. In elderly patients with IMN, desmin expression was associated with early EM stages and heavy proteinuria, which may reflect phenotypic alteration of the podocyte nephrin, podocin, ZO-1, CD2AP, and so on [Mundel and Shankland 2002]. In diseased glomeruli, their expression and distribution is markedly altered from continuous distribution to discontinuous distribution along the glomerular capillary wall. However, the change in nephrin expression and its association with proteinuria in the immune complex-associated type of nephrotic syndrome such as IMN is poorly understood.
Because few reports are available with pathological information on elderly patients with IN/lN, several clinical parameters were compared between elderly and younger ININ patients in this study. These parameters included daily proteinuria, morphological stages of EM in renal biopsy specimens and markers of podocyte injury, including desmin and nephrin.