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A Heterologous Model of Thrombospondin Type 1 Domain-Containing 7A-Associated Membranous Nephropathy.

ABSTRACT: Thrombospondin type 1 domain-containing 7A (THSD7A) is a target for autoimmunity in patients with membranous nephropathy (MN). Circulating autoantibodies from patients with THSD7A-associated MN have been demonstrated to cause MN in mice. However, THSD7A-associated MN is a rare disease, preventing the use of patient antibodies for larger experimental procedures. Therefore, we generated antibodies against the human and mouse orthologs of THSD7A in rabbits by coimmunization with the respective cDNAs. Injection of these anti-THSD7A antibodies into mice induced a severe nephrotic syndrome with proteinuria, weight gain, and hyperlipidemia. Immunofluorescence analyses revealed granular antigen-antibody complexes in a subepithelial location along the glomerular filtration barrier 14 days after antibody injection, and immunohistochemistry for rabbit IgG and THSD7A as well as ultrastructural analyses showed the typical characteristics of human MN. Mice injected with purified IgG from rabbit serum that was taken before immunization failed to develop any of these changes. Notably, MN developed in the absence of detectable complement activation, and disease was strain dependent. In vitro, anti-THSD7A antibodies caused cytoskeletal rearrangement and activation of focal adhesion signaling. Knockdown of the THSD7A ortholog, thsd7aa, in zebrafish larvae resulted in altered podocyte differentiation and impaired glomerular filtration barrier function, with development of pericardial edema, suggesting an important role of THSD7A in glomerular filtration barrier integrity. In summary, our study introduces a heterologous mouse model that allows further investigation of the molecular events that underlie MN.

SUBMITTER: Tomas NM

PROVIDER: S-EPMC5661286 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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A Heterologous Model of Thrombospondin Type 1 Domain-Containing 7A-Associated Membranous Nephropathy.

Tomas Nicola M NM Meyer-Schwesinger Catherine C von Spiegel Hanning H Kotb Ahmed M AM Zahner Gunther G Hoxha Elion E Helmchen Udo U Endlich Nicole N Koch-Nolte Friedrich F Stahl Rolf A K RAK

Journal of the American Society of Nephrology : JASN 20170816 11

Thrombospondin type 1 domain-containing 7A (THSD7A) is a target for autoimmunity in patients with membranous nephropathy (MN). Circulating autoantibodies from patients with THSD7A-associated MN have been demonstrated to cause MN in mice. However, THSD7A-associated MN is a rare disease, preventing the use of patient antibodies for larger experimental procedures. Therefore, we generated antibodies against the human and mouse orthologs of THSD7A in rabbits by coimmunization with the respective cDNA ...[more]

PMID: 28814510

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Project description:BackgroundIdiopathic 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.MethodsUsing 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.ResultsSerum 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.ConclusionsIn 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.).

Dataset Information

A Heterologous Model of Thrombospondin Type 1 Domain-Containing 7A-Associated Membranous Nephropathy.

Publications

A Heterologous Model of Thrombospondin Type 1 Domain-Containing 7A-Associated Membranous Nephropathy.

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