Immunoexpression of CD2-associated protein, α-actinin-4 and podocalyxin in idiopathic membranous glomerulopathy and membranous lupus nephritis

Background and Purpose: In glomerulopathies accompanied by a nephrotic syndrome, simplified organization of podocytes is seen in electron microscopy. It is suggested that glomerular epithelial proteins play a role in foot process formation and are crucial in normal function of glomerular filtration apparatus. Therefore, the present study was undertaken to evaluate the immunoexpression of podocyte-associated proteins in two types of glomerulopathies with ultrastructural evidence of foot process effacement and in normal glomeruli. Material and Methods: Immunoperoxidase staining was carried out using antibodies against CD2-associated protein (CD2AP), alpha-actinin-4 and podocalyxin on renal biopsy specimens in 17 patients with idiopathic membranous glomerulopathy (MG), 10 patients with membranous lupus nephritis (MLN) and 10 control renal tissues. Results: Our study revealed upregulation in alpha-actinin-4 immunoexpression in patients with MG and MLN. The immunostaining of podocalyxin was weak and granular in podocytes in patients with glomerulopathies as compared with normal controls, but statistical analyst's did not reach significant differences between groups. In diseased glomeruli podocyte-associated proteins were detected in granular pattern. There were no differences in the intensity of immunostaining of glomerular molecules between MG and MLN patients. The immunoexpression of a-actinin-4 and podocalyxin was significantly correlated with the intensity of proteinuria. Conclusions: Our results A owed similarities in the CD2AP alpha-actinin-4 and podocalyxin immunoexpression in MG and MLN patients and suggest that the alterations in the glomerular immunoexpression of these podocyte-associated molecules occur irrespective of the nature of disease and probably are related to the structural changes in podocyte foot processes.