Abstract: PO1469
Contactin 1: A New Antigen in Membranous Nephropathy Associated with Chronic Inflammatory Polyneuropathy
Session Information
- Glomerular Diseases: Immunology and Inflammation in IgANP, C3GP, TMA, and Nephrotic Diseases
November 04, 2021 | Location: On-Demand, Virtual Only
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1202 Glomerular Diseases: Immunology and Inflammation
Authors
- Santoro, Domenico, Universita degli Studi di Messina, Messina, Sicilia, Italy
- Longhitano, Elisa, Universita degli Studi di Messina, Messina, Sicilia, Italy
- Torreggiani, Massimo, Centre Hospitalier du Mans, Le Mans, Pays de la Loire, France
- Barreca, Antonella, Azienda Ospedaliero Universitaria Citta della Salute e della Scienza di Torino, Torino, Piemonte, Italy
- Vegezzi, Elisa, Fondazione Istituto Neurologico Nazionale C Mondino Istituto di Ricovero e Cura a Carattere Scientifico, Pavia, Lombardia, Italy
- Piccoli, Giorgina B., Centre Hospitalier du Mans, Le Mans, Pays de la Loire, France
- Mazzeo, Anna, Universita degli Studi di Messina, Messina, Sicilia, Italy
- Russo, Massimo, Universita degli Studi di Messina, Messina, Sicilia, Italy
- Toscano, Antonio, Universita degli Studi di Messina, Messina, Sicilia, Italy
- Debiec, Hanna, INSERM, Paris, Île-de-France, France
- Ronco, Pierre M., INSERM, Paris, Île-de-France, France
Introduction
In recent years, several new antigens have been characterized in membranous nephropathy (MN), but those involved in association with demyelinating neuropathy remain elusive. Although several antibody specificities were identified in this group of autoimmune neuropathies with or without glomerular involvement, there is no evidence for the deposition of the relevant antibodies in glomeruli. We investigated a patient with such association.
Case Description
A 73 y/o woman was referred to the neurology department for weakness and ataxic gait. Romberg's manoeuvre was positive. On examination, thermal and nociceptive hypoesthesia and hypopallestesia were found. Electromyography demonstrated sensory-motor axonal polyneuropathy, compatible with a chronic inflammatory demyelinating polyneuropathy (CIDP). Blood tests showed normal kidney function (eGFR 73 ml/min) and hypoalbuminemia (2.89 g/dl); 24h proteinuria was 3.6 g/24h. Autoantibodies (ANA, ENA, DNA, LAC, anti-cardiolipin, ANCA) were undetectable, serum immunoglobulins and C3 and C4 complement components were normal. A kidney biopsy (KB) demonstrated a picture of MN. Anti-PLA2R antibody was negative in the serum and PLA2R and THSD7A antigens were not detected in the KB. Three CIDP-associated autoantibodies (anti-contactin 1 (CNTN1), anti-contactin associated protein 1 and anti-neurofascin) were tested by ELISA which revealed the presence of anti-CNTN1 at 1:100 serum dilution. CNTN1 antigen was revealed by immunohistochemistry in the subepithelial immune deposits in the patient's paraffin biopsy sections but not in control PLA2R-positive KB (figure 1).
Discussion
CNTN1 should be added to the armamentarium of antigens involved in MN and tested in PLA2R negative MN associated with CIDP. Further studies are needed to determine the prevalence of CNTN1-associated MN among patients with CIDP, and in those without CIDP and as yet unidentified antigen.