title: Immunodominant epitopes of alpha3(IV)NC1 induce autoimmune glomerulonephritis in rats.
abstract: BACKGROUND
  The major Goodpasture antibody binding epitopes have been localized to the amino-terminal third of the noncollagenous domain (NC1) of the alpha3 chain of type IV collagen [alpha3(IV)NC1]. The present study determined whether the same epitopes induce glomerulonephritis in rats.
  
  
  METHODS
  We immunized Wistar Kyoto (WKY) rats with human alpha3(IV)/alpha1(IV)NC1 chimeric proteins or full-length recombinant alpha3(IV)NC1 (alpha3732). Chimeric protein constructs were thirds of alpha3(IV)NC1 (CP333) replaced by corresponding sequences of homologous nonreactive alpha1(IV)NC1 (CP111). All chimeric proteins contained 30 amino acids of type X collagen at the amino terminus except alpha3732. Two other constructs, T195 EA (EA) and T194 EB (EB), were entirely alpha1(IV)NC1, except for antibody-immunodominant amino acids from the first and second thirds of alpha3(IV)NC1.
  
  
  RESULTS
  Construct immunized animals developed specific antibody responses to recombinant proteins and native human, bovine and rat NC1. CP311 immunized rats, as well as alpha3732 rats, had glomerular IgG, fibrin, and glomerulonephritis with proteinuria by 3 weeks. CP331 produced more severe disease, comparable to positive controls. CP111 produced no disease. EA, but not EB, induced severe glomerulonephritis. Half-dose each of EA plus EB induced disease identical to full-dose EA alone.
  
  
  CONCLUSIONS
  The amino third of alpha3(IV)NC1 which contains the major epitope for Goodpasture antibody binding, also induces glomerulonephritis in rats. The middle third of alpha3(IV)NC1 does not induce glomerulonephritis but appears to enhance disease with the amino terminal third. Finally, the presence of the collagen X leader sequence appears to convey greater nephritogenicity. These studies suggest that not only the nephritogenic epitope itself, but flanking sequences and the conformational context of the nephritogenic epitope may influence its ability to cause glomerulonephritis.
authors: Department of Medicine, University of Virginia Health Sciences Center, Charlottesville, Virginia 22908-0133, USA.
authors: Lanlin
authors: L
authors: Chen
authors: Thomas
authors: T
authors: Hellmark
authors: Jörgen
authors: J
authors: Wieslander
authors: Warren Kline
authors: WK
authors: Bolton
mesh_terms: D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000276:immunology*; D001327:Autoimmune Diseases / Q000276:immunology*; D001806:Blood Urea Nitrogen; D002417:Cattle; D024141:Collagen Type IV / Q000235:genetics / Q000276:immunology*; D003404:Creatinine / Q000097:blood; D005340:Fibrinogen / Q000032:analysis; D005455:Fluorescent Antibody Technique; D005921:Glomerulonephritis / Q000276:immunology*; D006417:Hematuria / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology*; D007074:Immunoglobulin G / Q000032:analysis; D007668:Kidney / Q000737:chemistry / Q000473:pathology; D008297:Male; D017434:Protein Structure, Tertiary; D011507:Proteinuria / Q000276:immunology; D051381:Rats; D011921:Rats, Inbred WKY; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D001324:Autoantigens; D024141:Collagen Type IV; D016056:Immunodominant Epitopes; D007074:Immunoglobulin G; D011993:Recombinant Fusion Proteins; C057112:type IV collagen alpha3 chain; D005340:Fibrinogen; D003404:Creatinine