Membranous Nephropathy (MN) is characterized by the presence of subepithelial deposits. MN has been traditionally classified as primary if it is not associated with other pathologies, or secondary if it is associated with autoimmune diseases, infections or malignancies. The identification of target podocyte antigen was a critical point in the understanding of the disease: firstly in 2009 with M-type phospholipase A2 receptor (PLA2R) and then in 2014 with Thrombospondin Type 1 Domain Containing 7A (THSD7A). In the last years using an innovative approach based on laser microdissection and tandem mass spectrometry (MS/MS) has allowed the identification of new target antigen/protein as EXT1/2, NELL-1, NCAM1, SEMA3B, PCHD7, HTRA1, TGFBR3. Some of these proteins have been found in both primary and secondary MN, blurring the line between the two forms. Further studies are necessary to define and understand the clinical features of different antigen associated diseases. The aim of this review is to take a closer look at the new antigens and to evaluate how their discovery can change MN classification.
Keywords: Membranous Nephropathy, Renal Pathology, podocyte antigens, mass spectrometry