Cross-reactivity of anti-PLA2R1 autoantibodies to rabbit and mouse PLA2R1 antigens and development of two novel ELISAs with different diagnostic performances in idiopathic membranous nephropathy

Biochimie. 2015 Nov;118:104-15. doi: 10.1016/j.biochi.2015.08.007. Epub 2015 Aug 19.

Abstract

About 70% of patients with idiopathic membranous nephropathy (iMN) have autoantibodies to the phospholipase A2 receptor PLA2R1. We screened sera from iMN patients for their cross-reactivity to human (h), rabbit (rb) and mouse (m) PLA2R1 by western blot (WB) and antigen-specific ELISAs. All iMN patients recognized hPLA2R1 and rbPLA2R1 by WB, and a rbPLA2R1 ELISA was as sensitive as the standardized hPLA2R1 ELISA to monitor anti-PLA2R1 in patients with active disease or in drug-induced remission. In contrast, only 51% of patients were reactive to mPLA2R1 by WB, and a maximum of 78% were weakly to highly positive in the mPLA2R1 ELISA, suggesting that iMN patients exhibit different subsets of anti-PLA2R1 autoantibodies against epitopes that are shared or not among PLA2R1 orthologs. In a cohort of 41 patients with a mean follow-up of 42 months from anti-PLA2R1 assay, the detection of anti-mPLA2R1 autoantibodies was an independent predictor of clinical outcome in multivariate analysis (p = 0.009), and a ROC curve analysis identified a threshold of 605 RU/mL above which 100% of patients (12 patients) had a poor renal outcome (p < 0.001). A similar threshold could not be defined in hPLA2R1 and rbPLA2R1 ELISAs. We conclude that rbPLA2R1 is an alternative antigen to hPLA2R1 to measure anti-PLA2R1 in active disease while mPLA2R1 is a unique antigen that can detect a subset of anti-PLA2R1 autoantibodies present at high levels (>605 RU/mL) only in iMN patients at risk of poor prognosis, and is thus useful to predict iMN outcome.

Trial registration: ClinicalTrials.gov NCT01897961.

Keywords: Autoimmunity; Conformational epitope; ELISA; Membranous nephropathy; Mouse PLA2R1; Orthologs; PLA2R1 autoantibodies; Rabbit PLA2R1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autoantibodies / immunology*
  • Autoantigens / immunology*
  • Blotting, Western
  • Cross Reactions
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Glomerulonephritis, Membranous / diagnosis*
  • Humans
  • Rabbits
  • Receptors, Phospholipase A2 / immunology*

Substances

  • Autoantibodies
  • Autoantigens
  • PLA2R1 protein, human
  • Pla2r1 protein, mouse
  • Receptors, Phospholipase A2

Associated data

  • ClinicalTrials.gov/NCT01897961