Genetic and Iatrogenic Defects in Peripheral Tolerance Associated with Anti-Nephrin Antibody-Associated Minimal...

Minimal change disease (MCD) is a common cause of nephrotic syndrome in children and adults. Immune dysregulation is a contributor, but the relative roles of individual components of the immune system in MCD pathogenesis remain unclear.

Here, we present 2 patients with defects in immune tolerance mechanisms that developed MCD associated with anti-nephrin antibodies. The first patient had a pathogenic deletion in FOXP3, leading to reduced regulatory T cells. Serum could not be obtained from this patient during the active phase of MCD to directly establish the presence of anti-nephrin antibodies. However, this patient demonstrated IgG dusting over podocyte cell bodies by immunofluorescence microscopy, as well as colocalization of IgG with nephrin in confocal microscopy. The second patient developed MCD in the context of immune checkpoint inhibitor treatment for metastatic carcinoma. Anti-nephrin antibodies were detected in this patient during active disease. The patient's kidney biopsy also showed evidence of binding of anti-nephrin antibodies within the glomeruli.

These cases demonstrate that genetic and iatrogenic mechanisms of breakdown in peripheral tolerance can lead to MCD.