title: Binding of autoantibodies to the core region of tissue transglutaminase is a feature of paediatric coeliac disease.
abstract: OBJECTIVE
  Production of autoantibodies to the enzyme tissue transglutaminase (tTG) is a hallmark of coeliac disease (CD). We have previously demonstrated that the immumoglobulin (Ig) A response to tTG in adult CD specifically targets its catalytic core region, containing the active-site triad of amino acids. The aim of the present study was to investigate this phenomenon in paediatric patients with CD, and to elucidate the contribution of each active-site residue to epitopes recognised. The specificity of the IgG anti-tTG response was also investigated and compared with that of the IgA anti-tTG response, in both paediatric and adult patients with CD.
  
  
  METHODS
  Wild-type and novel variants of tTG were generated via site-directed mutagenesis and expressed as glutathione-S-transferase-fusion proteins in Escherichia coli BL-21. The mutagenic variants of tTG had substitutions of 1, 1, or all of the 3 of the catalytic triad amino acids. All of the recombinant tTGs were tested for their antigenicity in IgA and IgG enzyme-linked immunosorbent assays with cohorts of paediatric (n=63) and adult (n=30) CD sera.
  
  
  RESULTS
  Substitution of even 1 amino acid in the catalytic triad resulted in a significant reduction of CD IgA and IgG anti-tTG binding, with all of the mutant proteins displaying diminished antigenicity compared with the wild-type protein.
  
  
  CONCLUSIONS
  The core region of tTG is specifically targeted from early on in disease course by CD patient autoantibodies of both the IgA and IgG class.
authors.affiliation: National Children's Research Centre, Dublin †Dublin Institute of Technology, Dublin, Ireland. comerfr@tcd.ie
authors.forename: Ross
authors.initials: R
authors.lastname: Comerford
authors.forename: Greg
authors.initials: G
authors.lastname: Byrne
authors.forename: Conleth
authors.initials: C
authors.lastname: Feighery
authors.forename: Jacinta
authors.initials: J
authors.lastname: Kelly
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D002446:Celiac Disease / Q000097:blood / Q000201:enzymology* / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D004926:Escherichia coli; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000276:immunology; D011503:Transglutaminases / Q000276:immunology*; D055815:Young Adult
chemical_list: D000596:Amino Acids; D001323:Autoantibodies; D000939:Epitopes; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D011503:Transglutaminases