Lipoprotein apheresis for anti-nephrin antibody-positive steroid-resistant nephrotic syndrome: a pediatric case report.

Steroid-resistant nephrotic syndrome (SRNS) in children carries a poor prognosis, and recent discoveries implicate anti-nephrin autoantibodies (ANABs) as mediators of podocyte injury. Lipoprotein apheresis, originally developed for familial hypercholesterolemia, has been explored as rescue therapy in refractory SRNS, but its immunologic effects remain uncertain. This case demonstrates a decline in ANAB titers accompanied by clinical improvement following lipoprotein apheresis. We report a 7-year-old male of Afro-Caribbean descent with biopsy findings consistent with minimal change disease and punctate IgG staining who presented with steroid-resistant nephrotic syndrome. He was unresponsive to tacrolimus, rituximab, mycophenolate mofetil, and five therapeutic plasma exchange sessions, and developed severe anasarca requiring extracorporeal ultrafiltration. Compassionate-use lipoprotein apheresis was initiated. Twelve sessions were performed over about ten weeks. Serial plasma ANAB testing showed a marked decrease with lipoprotein apheresis. Clinically, urine output increased, edema resolved, and ultrafiltration was discontinued about seven weeks after the final session, although nephrotic-range proteinuria persisted. This case highlights the potential immunomodulatory role of lipoprotein apheresis in ANAB-mediated podocytopathy. Improvement despite lack of response to therapeutic plasma exchange suggests that lipoprotein apheresis may remove certain antibodies and immune complexes more efficiently compared to conventional therapeutic plasma exchange. Serial ANAB monitoring provided a biomarker correlating with treatment response. Controlled studies are needed to clarify the mechanisms and define the role of lipoprotein apheresis in ANAB-positive SRNS patients.