When the physiopathology of membranous nephropathy was first described, almost 30% of cases were recognized to be secondary to well-known diseases such as autoimmune diseases, tumors or infections. The remaining 70% cases were called primary membranous nephropathy as the exact mechanism or pathogenic factor involved was unknown. The discovery of the M type phospholipase A2 receptor and thrombospondin type 1 domain containing 7A as causative antigens in these “so called” primary membranous nephropathies provided new insights into the effective causes of a large proportion of these cases. Novel techniques such as laser microdissection and tandem mass spectrometry as well as immunochemistry with antibodies directed against novel proteins allowed the confirmation of new involved antigens. Finally, using confocal microscopy to localize these new antigens and immunoglobulin G and Western blot analysis of serum samples, these new antigens were detected on the glomerular membrane, and the related antibodies were detected in serum samples. The same antigens have been recognized in some cases of secondary membranous disease due to autoimmune diseases, tumors and infections. This has allowed examination of the relationship between antigens in primary membranous nephropathy and their presence in some secondary nephropathies. The aim of this study is to describe the characteristics of the new antigens discovered and their association with other diseases.

Membranous nephropathy (MN) is the major cause of nephrotic syndrome in adults, accounting for 20% of cases with an annual incidence of 1 per 100,000 population. In the past 10 years, the role of podocytes has been identified. Environmental triggers in genetically predisposed patients can activate podocytes to exhibit antigenic epitopes, including PLA2R, THBS1, and NELL1, which become targets of specific autoantibodies with subsequent complement activation. The discovery of these mechanisms has opened a new horizon in the treatment of MN, and novel drugs are available with more specific mechanisms of action. Rituximab, a monoclonal antibody directed against CD20 expressed on B lymphocytes, has been used in several trials and appears to induce remission of nephrotic syndrome in 60% of patients (GEMRITUX trial). The recently published results of the MENTOR trial documented the superior efficacy of rituximab in patients observed for up to 24 months. In MN, the concept of targeting disease control has introduced novel therapies with specific blocking mechanisms, such as belimumab; nonspecific blocking mechanisms, such as those against adrenocorticotropic hormone; and new therapeutic options, such as ofatumumab, bortezomib, and eculizumab, which have recognised the pathological processes involved in the glomerular diseases.