Identification of immunodominant epitopes of α-gliadin in HLA-DQ8 transgenic mice following oral immunization

Stefania Senger, Francesco Maurano, Maria F. Mazzeo, Marcello Gaita, Olga Fierro, Chella S. David, Riccardo Troncone, Salvatore Auricchio, Rosa A. Siciliano, Mauro Rossi

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41 Scopus citations

Abstract

Celiac disease, triggered by wheat gliadin and related prolamins from barley and rye, is characterized by a strong association with HLA-DQ2 and HLA-DQ8 genes. Gliadin is a mixture of many proteins that makes difficult the identification of major immunodominant epitopes. To address this issue, we expressed in Escherichia coli a recombinant α-gliadin (r-α-gliadin) showing the most conserved sequence among the fraction of α-gliadins. HLA-DQ8 mice, on a gluten-free diet, were intragastrically immunized with a chymotryptic digest of r-α-gliadin along with cholera toxin as adjuvant. Spleen and mesenteric lymph node T cell responses were analyzed for in vitro proliferative assay using a panel of synthetic peptides encompassing the entire sequence of r-α-gliadin. Two immunodominant epitopes corresponding to peptide p13 (aa 120-139) and p23 (aa 220-239) were identified. The response was restricted to DQ and mediated by CD4+ T cells. In vitro tissue transglutaminase deamidation of both peptides did not increase the response; furthermore, tissue transglutaminase catalyzed extensive deamidation in vitro along the entire r-α-gliadin molecule, but failed to elicit new immunogenic determinants. Surprisingly, the analysis of the cytokine profile showed that both deamidated and native peptides induced preferentially IFN-γ secretion, despite the use of cholera toxin, a mucosal adjuvant that normally induces a Th2 response to bystander Ags. Taken together, these data suggest that, in this model of gluten hypersensitivity, deamidation is not a prerequisite for the initiation of gluten responses.

Original languageEnglish (US)
Pages (from-to)8087-8095
Number of pages9
JournalJournal of Immunology
Volume175
Issue number12
DOIs
StatePublished - Dec 15 2005

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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