Abstract: TH-OR029
Ubiquitin Carboxyl-Terminal Hydrolase L1 Is a Podocyte Target of IgG Antibodies in Idiopathic Nephrotic Syndrome (INS)
Session Information
- Clinical Glomerular Disorders: Trials, Treatment, Case Findings
November 02, 2017 | Location: Room 292, Morial Convention Center
Abstract Time: 06:06 PM - 06:18 PM
Category: Glomerular
- 1001 Glomerular: Basic/Experimental Immunology and Inflammation
Authors
- Deschênes, Georges, Hospital Robert Debre, Paris, France
- Jamin, Agnes, INSERM U1149 & ELR8252 CNRS, 75018 Paris, France
- Berthelot, Laureline, INSERM U699, Paris, France
- Monteiro, Renato C., Bichat Medical School, Paris, France
Background
The efficiency of B cell-depleting treatments highlights the involvement of B cells in INS. This study searched for identifying antibodies (Abs) directed against podocytes in patients with INS.
Methods
The study was performed using a biobank including 86 patients sampled at various stages of INS and 76 controls. Fractions of plasma obtained by size exclusion chromatography and tested on cultured podocyte adhesion; specificities of IgG Abs contained in the plasma fraction of interest were studied through immunoprecipitation of a podocyte lysate then identification of cognate antigens by liquid chromatography-mass spectrometry.
Results
Cultured podocyte detachment was observed with one specific plasma fraction in 16/34 INS relapsing patients, 1/11 INS patients in remission and 0/25 controls. IgG were isolated from this specific plasma fraction in 3 INS relapsing patients (all detaching cultured podocytes), 3 from the same INS patients in remission (all not detaching cultured podocytes) and in 3 controls, then used to immunoprecipitate a podocyte lysate. Comparative proteomic analysis allowed selecting 5 proteins according to statistical and biological criteria. Specific Abs were tested and only anti-Ubiquitin Carboxyl-Terminal Hydrolase L1 (UCHL1) IgG led to podocyte detachment. Pre-incubation of either anti-UCHL1 IgG Abs or plasma fractions with recombinant UCHL1 prevented podocyte detachment. Plasma levels of anti-UCHL1 IgG Abs were increased in 18/42 relapsing INS patients over the highest level of 38 controls (median=0.20 AU/*g of total IgG;IQ0.15-0.29;range0.07-0.85). For those 18 patients, the level of anti-UCHL1 IgG Abs in 43 samples available at various stage of INS was confirmed to be significantly higher in relapse (n=23;median=1.22AU/µg of total IgG; IQ 0.92-1.90) compared to remission (n=20;median=0.51;IQ 0.33-0.77;p<0.001). In those 18 INS patients, proteinuria correlated with anti-UCHL1 IgG Abs level (n=43,r=0.57,p<0.001).
Conclusion
UCHL1 is involved in the adhesion of cultured podocytes. UCHL1 is a target of circulating IgG Abs in a subset of relapsing INS patients.
Funding
- Private Foundation Support