Anti-phospholipase A2 receptor antibodies and the pathogenesis of membranous nephropathy.

Since the early 2000s, considerable advances have been achieved in the understanding of molecular pathomechanisms of human membranous nephropathy (MN), inspired by studies of Heymann nephritis, a faithful experimental model. These studies led to the identification of neutral endopeptidase, the type-M phospholipase A2 receptor (PLA2R), and cationic bovine serum albumin as target antigens of circulating and deposited antibodies in neonatal alloimmune, adult 'idiopathic', and early childhood MN, respectively. A genome-wide association study further showed a highly significant association of the PLA2R1 and the HLA-DQA1 loci with idiopathic MN in patients of white ancestry. The time has come to revisit the spectrum of MN based on the newly identified antigen-antibody systems which should be considered as molecular signatures of the disease, challenging the uniform histological definition. Although some uncertainties remain as to the pathogenic effects of anti-PLA2R antibodies because of the lack of an appropriate experimental model, the value of these antibodies as biomarkers for diagnosis and disease activity is increasingly being recognized. It is not exaggerated to state that they have induced a paradigm shift in the monitoring of patients with MN, thus opening a new era of personalized medicine.