| Description |
Recurrence of focal segmental glomerulosclerosis (rFSGS) after kidney transplantation is a cause of early and accelerated graft loss. Immuneadsorption can alleviate renal dysfunction and suggests that circulating antibodies (Ab) are likely implicated in disease pathogenesis. To evaluate pathogenic Ab in rFSGS, we processed 141 unique serum samples from patients with and without primary rFSGS (n=64) and 34 non-FSGS control, transplanted at five (US and EU) hospitals. 9000 antigens were screened in pre-transplant sera by protein arrays and 10 Ab targeting glomerular antigens were selected for ELISA validation. A panel of 7 Ab (CD40, PTPRO, CGB-5, FAS, P2RY11, SNRPB2 and APOL2) could predict post-transplant FSGS recurrence with 92% accuracy. Pre-transplant elevation of anti-CD40 Ab levels alone had a substantial impact (78% accuracy) on the identification of rFSGS risk after transplantation. Epitope mapping of CD40 with customized peptide arrays and rFSGS sera demonstrated altered immunogenicity of the extracellular CD40 domain in rFSGS. Immunohistochemistry of CD40 demonstrated a differential expression of these antigens in FSGS compared to non-FSGS. Anti-CD40 Ab purified from rFSGS patients were uniquely pathogenic in human podocyte cultures; injection of these Ab resulted in heightened proteinuria, independently and in combination with suPAR in a rodent model, abrogated by injection of monoclonal Ab to CD40. In conclusion, a panel of 7 Ab can identify primary FSGS patients at high risk of recurrence prior to transplantation, allowing for customized therapies and improved patient selection for transplant. Intra-renal CD40 is an important axis of disease pathogenesis, and human trials of anti-CD40 therapies are warranted to evaluate their efficacy in preventing rFSGS and improving graft survival. |
