New insights into the pathophysiology of idiopathic nephrotic syndrome

Corticoresistant idiopathic nephrotic syndrome (INS) is a glomerulopathy of unknown etiology whose original aspect is its recurrence after kidney transplantation in 30 to 50% of patients with end-stage renal disease. This suggests the involvement of circulating factors that would alter the glomerular filtration barrier, but whose nature remains elusive. Although a T cell. immune origin has been suggested, the actual role of these cells in INS recurrence is still unclear. Here we present an 8-year-old patient with corticoresistant INS who developed a recurrence of her initial disease after kidney transplantation. Rituximab therapy was proposed 11 months after transplantation; although no immediate effect was induced, a slow but persistent decrease in proteinuria began a few months after Rituximab infusions despite cessation of plasma exchanges and steroid therapy. The pathophysiology of INS and the putative mechanisms of action of Rituximab are discussed. (C) 2009 Elsevier Inc. All rights reserved.