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Abstract: PO1732

Urinary Biomarkers as a Tool for Monitoring Remissions and Predicting Relapses in Autoimmune Glomerulonephritis

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Genest, Suzanne Dominique, Hopital du Sacre-Coeur de Montreal, Montreal, Quebec, Canada
  • Khalili, Myriam, Hopital du Sacre-Coeur de Montreal, Montreal, Quebec, Canada
  • Rioux, Jean-Philippe, Hopital du Sacre-Coeur de Montreal, Montreal, Quebec, Canada
  • Quadri, Jérémy, Centre Hospitalier Universitaire Sainte-Justine, Montreal, Quebec, Canada
  • Bonnefoy, Arnaud, Centre Hospitalier Universitaire Sainte-Justine, Montreal, Quebec, Canada
  • Troyanov, Stephan, Hopital du Sacre-Coeur de Montreal, Montreal, Quebec, Canada
Background

Complement-mediated injury, inflammation and fibrosis play central roles in the pathogenesis of autoimmune glomerulonephritis. The use of urinary biomarkers as a surrogate of these pathways of injury could assist clinicians during the clinical follow-up. We investigated the value of urinary biomarkers of complement activation, inflammation and fibrosis during periods of sustained remission among patients with autoimmune glomerulonephritis.

Methods

We prospectively examined 100 patients with ANCA-associated vasculitis, focal segmental glomerulosclerosis, IgA nephropathy, lupus nephritis, membranoproliferative glomerulonephritis and membranous nephropathy. Proteinuria, urinary sC5b-9, monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor-β1 (TGF-β1), expressed as creatinine ratios, were measured at presentation and during follow-up visits. We used standard definitions of remission and relapse for each type of glomerulonephritis. Wilcoxon signed-rank test was used to compare changes in urinary biomarkers during remissions and relapses.

Results

We identified 95 periods of active disease and 82 episodes of sustained remission. Inactive periods lasted a median of 22 (11-32) months. Eighty percent (n=66) of these were not followed by a relapse. During these episodes of remission, urinary biomarkers continued to steadily decrease, achieving a reduction of 40% for proteinuria, 40% for urinary sC5b-9, 38% for MCP-1 and 40% for TGF-β1 (all p < 0.05). Twenty percent (n=16) of inactive periods reflected remissions with subsequent relapses. Biomarker levels during the inactive period preceding relapses did not significantly change for proteinuria (+8%), urinary sC5b-9 (+15%) and MCP-1 (4%), while they decreased for TGF-β1 (-30%, p=0.02). During relapses, we observed a 3.2-fold (1.9-8.3) increase in proteinuria and a significantly greater 8.5-fold (4.2-56.9) increase in urinary sC5b-9 (p=0.001). By contrast, urinary MCP-1 and TGF-β1 increased significantly less than proteinuria.

Conclusion

Failure to achieve a sustained reduction in urinary biomarkers during remission was associated with a subsequent risk of relapse of autoimmune glomerulonephritis. Urinary sC5b-9 appears to be a more discerning marker of immunological relapse.

Funding

  • Private Foundation Support