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Abstract: SA-OR061

Relationship between IgA1 Lectin-Binding Specificities, Mesangial C4d Deposits, and Clinical Phenotypes in IgA Nephropathy

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Martin-conde, Luisa, University Hospital Arnau de Vilanova, Lleida, Spain
  • Jatem, Elias A., Hospital Universitari Arnau de Vilanova, Lleida, Spain
  • Carnicer, Clara, Hospital Universitari Vall d''Hebron, Barcelona, Spain
  • Molina, Maria, University Hospital Arnau de Vilanova, Lleida, Spain
  • Martínez, Cristina, Vall d''Hebron Institute of Research, Barcelona, Spain
  • Colàs-Campàs, Laura, IRB Lleida - University of Lleida, Lleida, Spain
  • Carrasco, Alicia Garcia, Vascular and Renal Translational Research Group. IRB Lleida, Lleida, Spain
  • Segarra, Alfonso, Servicio Nefrologia Hospital Vall D'Hebron, Barcelona, Spain
Background

The reason why mesangial C4d deposits are detected in only certain biopsies of IgA nephropathy, remains unclear. In this study, we analyse the association between different patterns of IgA1 glycosilation, mesangial C4 deposition and clinical phenotypes, in IgA nephropathy

Methods

This cross-sectional study included 145 patients with idiopathic IgA nephropathy. We measured the serum levels of three different IgA1 lectin-binding specificities, using enzyme-linked-immunosorbent assays, and we analysed the relationship between these specificities, C4d mesangial deposits and clinical profiles at diagnosis.

Results

C4d-positive vs. Cd4-negative patients had higher proteinuria (median: 3.1 g/g [0.9-4.2] vs. 1.8 g/g [1-2.2]; p=0.000), hematuria (223 cel/µL [32-278] vs 99 cel/µL [25-186] , p=0.000 ), and higher levels of IgA1 with ability to bind Helix Aspersa (HAA IgA1) (150.6 ± 52 U vs 96.2 ± 64.1 U, p= 0,000), Triticum vulgaris (TVIgA1) ( 85.1 ± 31.7 U vs 42.2 ± 26.9U , p= 0.000 ) and Canavalia ensiformis ( ConAIgA1) (32.5 ± 18U vs 16.7 ± 9.38U , p=0.000) but similar levels of total galactose-deficient IgA1 (338 ± 64 U vs 324 ± 43U p: 0.15). The levels of HAAIgA1, TVIgA1 and ConAIgA1 were all associated with the mesangial deposition of C4d, extracapillary proliferation and the presence of acute kidney injury. HAAIgA1, TVIgA1 and ConAIgA1 had a similar ability to discriminate between C4d positive ad C4d-negative biopsies ( AUC: 0.72 ± 0.04 , 0.83 ± 0.03 and 0.81 ± 0.04, respectively, p=0.000 in all cases). In logistic models ,TVIgA1 and ConAIgA1 were the only independent predictors of mesangial C4d deposits

Conclusion

In IgA nephropathy,the severity of the disease is associated with the level of desialylation of galactose-deficient IgA1 whereas C4d deposits are associated with elevated levels of IgA1 glycoforms involving aberrantly glycosilated N-linked glycan residues.