Kidney Week

Abstract: SA-PO956

Monoclonal Characterization of Autoreactive PLA2R1 Antibody Responses in Membranous Nephropathy (MN)

Session Information

• Glomerular Diseases: Translational Studies and Biomarkers
  November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

• Reinhard, Linda, III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Hamburg, Germany

Linda Reinhard,

• Montagner, Sara, Novartis AG, Basel, Basel-Stadt, Switzerland

Sara Montagner,

• Marchant, Martine, Novartis AG, Basel, Basel-Stadt, Switzerland

Martine Marchant,

• Iazeolla, Mariavittoria, Novartis AG, Basel, Basel-Stadt, Switzerland

Mariavittoria Iazeolla,

• Lavoisier, Alexandra, Novartis AG, Basel, Basel-Stadt, Switzerland

Alexandra Lavoisier,

• Traggiai, Elisabetta, Novartis AG, Basel, Basel-Stadt, Switzerland

Elisabetta Traggiai,

• Hoxha, Elion, III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Hamburg, Germany

Elion Hoxha,

Background

Membranous nephropathy (MN) is caused by circulating antibodies, which in 70-80% of cases are directed against PLA₂R1. The CysR domain of the PLA₂R1 is the immune dominant domain and all patients with PLA₂R1-induced MN exhibit antibodies against this domain of the protein. Today, all treatment options for MN are unspecific concerning the molecular disease pathogenesis.

Methods

We isolated PBMCs from patients with PLA₂R1-induced MN. Using tagged PLA₂R1, PLA₂R1-specific B cells were isolated and the corresponding B cell receptors were cloned, in order to produce monoclonal human PLA₂R1-antibodies (PLA₂R1-mAb) corresponding to autoantibodies from patients with MN. The inhibitory potential of these PLA₂R1-mAb for human PLA₂R1-antibody binding to PLA₂R1 was tested in vitro by competition ELISA using 60 sera from patients with PLA₂R1-induced MN and in vivo in a rat model, which expresses the human PLA₂R1 (hPLA₂R1) specifically on podocytes.

Results

In total, four PLA₂R1-mAb were cloned from PLA₂R1-specific B cells from patients with MN and bound epitopes on the CysR domain. Every PLA₂R1-mAb was tested for its inhibitory capability using 60 PLA₂R1-antibody positive sera from patients with PLA₂R1-induced MN. The PLA₂R1-mAb inhibited the PLA₂R1-antibody binding capacity of the patient sera by 45% - 96%. The inhibitory effect of each PLA₂R1-mAb was independent of the PLA₂R1-antibody level of the sera; i.e. the PLA₂R1-mAb with the highest inhibition of 96% exhibited a PLA₂R1-antibody inhibition of 95%, 96% and 96%, when sera with PLA₂R1-anitbody level of 40-79 U/ml, 80-250 U/ml and > 250 U/ml were used, respectively. PLA₂R1-mAb were injected into a rat with podocyte-specific hPLA₂R1-expression prior to passive transfer of human PLA₂R1-antibodies from patients with MN. This PLA₂R1-mAb led to an inhibition of PLA₂R1-antibody binding by 80% in vivo.

Conclusion

We report for the first time the characterization of human monoclonal antibodies specific for PLA₂R1 derived from memory B cells of MN patients. Cloned autoantibodies showed strong inhibition of PLA₂R1 autoantibody binding both in vitro and in vivo, opening the possibility of a potential PLA₂R1 epitope specific treatment.

Funding

• Commercial Support – Novartis, Basel, Switzerland