BACKGROUND: Idiopathic membranous nephropathy is an autoimmune disease. In approximately 70% of patients, it is associated with autoantibodies against the phospholipase A2 receptor 1 (PLA2R1). Antigenic targets in the remaining patients are unknown. METHODS: Using Western blotting, we screened serum samples from patients with idiopathic membranous nephropathy, patients with other glomerular diseases, and healthy controls for antibodies against human native glomerular proteins. We partially purified a putative new antigen, identified this protein by means of mass spectrometry of digested peptides, and validated the results by analysis of recombinant protein expression, immunoprecipitation, and immunohistochemical analysis. RESULTS: Serum samples from 6 of 44 patients in a European cohort and 9 of 110 patients in a Boston cohort with anti-PLA2R1-negative idiopathic membranous nephropathy recognized a glomerular protein that was 250 kD in size. None of the serum samples from the 74 patients with idiopathic membranous nephropathy who were seropositive for anti-PLA2R1 antibodies, from the 76 patients with other glomerular diseases, and from the 44 healthy controls reacted against this antigen. Although this newly identified antigen is clearly different from PLA2R1, it shares some biochemical features, such as N-glycosylation, membranous location, and reactivity with serum only under nonreducing conditions. Mass spectrometry identified this antigen as thrombospondin type-1 domain-containing 7A (THSD7A). All reactive serum samples recognized recombinant THSD7A and immunoprecipitated THSD7A from glomerular lysates. Moreover, immunohistochemical analyses of biopsy samples from patients revealed localization of THSD7A to podocytes, and IgG eluted from one of these samples was specific for THSD7A. CONCLUSIONS: In our cohort, 15 of 154 patients with idiopathic membranous nephropathy had circulating autoantibodies to THSD7A but not to PLA2R1, a finding that suggests a distinct subgroup of patients with this condition. (Funded by the French National Center for Scientific Research and others.).
BACKGROUND:Idiopathic membranous nephropathy is an autoimmune disease. In approximately 70% of patients, it is associated with autoantibodies against the phospholipase A2 receptor 1 (PLA2R1). Antigenic targets in the remaining patients are unknown. METHODS: Using Western blotting, we screened serum samples from patients with idiopathic membranous nephropathy, patients with other glomerular diseases, and healthy controls for antibodies against human native glomerular proteins. We partially purified a putative new antigen, identified this protein by means of mass spectrometry of digested peptides, and validated the results by analysis of recombinant protein expression, immunoprecipitation, and immunohistochemical analysis. RESULTS: Serum samples from 6 of 44 patients in a European cohort and 9 of 110 patients in a Boston cohort with anti-PLA2R1-negative idiopathic membranous nephropathy recognized a glomerular protein that was 250 kD in size. None of the serum samples from the 74 patients with idiopathic membranous nephropathy who were seropositive for anti-PLA2R1 antibodies, from the 76 patients with other glomerular diseases, and from the 44 healthy controls reacted against this antigen. Although this newly identified antigen is clearly different from PLA2R1, it shares some biochemical features, such as N-glycosylation, membranous location, and reactivity with serum only under nonreducing conditions. Mass spectrometry identified this antigen as thrombospondin type-1 domain-containing 7A (THSD7A). All reactive serum samples recognized recombinant THSD7A and immunoprecipitated THSD7A from glomerular lysates. Moreover, immunohistochemical analyses of biopsy samples from patients revealed localization of THSD7A to podocytes, and IgG eluted from one of these samples was specific for THSD7A. CONCLUSIONS: In our cohort, 15 of 154 patients with idiopathic membranous nephropathy had circulating autoantibodies to THSD7A but not to PLA2R1, a finding that suggests a distinct subgroup of patients with this condition. (Funded by the French National Center for Scientific Research and others.).
Authors: Cornelia Dähnrich; Lars Komorowski; Christian Probst; Barbara Seitz-Polski; Vincent Esnault; Jack F Wetzels; Julia M Hofstra; Elion Hoxha; Rolf A Stahl; Gérard Lambeau; Winfried Stöcker; Wolfgang Schlumberger Journal: Clin Chim Acta Date: 2013-03-27 Impact factor: 3.786
Authors: Julia M Hofstra; Laurence H Beck; David M Beck; Jack F Wetzels; David J Salant Journal: Clin J Am Soc Nephrol Date: 2011-04-07 Impact factor: 8.237
Authors: Barbora Svobodova; Eva Honsova; Pierre Ronco; Vladimir Tesar; Hanna Debiec Journal: Nephrol Dial Transplant Date: 2012-12-06 Impact factor: 5.992
Authors: Julia M Hofstra; Hanna Debiec; Colin D Short; Timotheé Pellé; Robert Kleta; Peter W Mathieson; Pierre Ronco; Paul E Brenchley; Jack F Wetzels Journal: J Am Soc Nephrol Date: 2012-09-06 Impact factor: 10.121
Authors: Christopher P Larsen; Nidia C Messias; Fred G Silva; Erick Messias; Patrick D Walker Journal: Mod Pathol Date: 2012-11-30 Impact factor: 7.842
Authors: Wenjun Ju; Casey S Greene; Felix Eichinger; Viji Nair; Jeffrey B Hodgin; Markus Bitzer; Young-Suk Lee; Qian Zhu; Masami Kehata; Min Li; Song Jiang; Maria Pia Rastaldi; Clemens D Cohen; Olga G Troyanskaya; Matthias Kretzler Journal: Genome Res Date: 2013-08-15 Impact factor: 9.043
Authors: Jürgen Floege; Robert H Mak; Bruce A Molitoris; Giuseppe Remuzzi; Pierre Ronco Journal: Nat Rev Nephrol Date: 2015-09-29 Impact factor: 28.314
Authors: Dawn J Caster; Liliane Hobeika; Jon B Klein; David W Powell; Kenneth R McLeish Journal: Proteomics Clin Appl Date: 2015-06-17 Impact factor: 3.494
Authors: Larissa Seifert; Elion Hoxha; Anna M Eichhoff; Gunther Zahner; Silke Dehde; Linda Reinhard; Friedrich Koch-Nolte; Rolf A K Stahl; Nicola M Tomas Journal: J Am Soc Nephrol Date: 2018-03-19 Impact factor: 10.121