Evaluation of Reduced Allergenicity of Deamidated Gliadin in a Mouse Model of Wheat-Gliadin Allergy Using an Antibody Prepared by a Peptide Containing Three Epitopes (1)
The associated clinical symptoms for wheat allergy differ between adults and children. Atopic eczema/dermatitis syndrome (AEDS) often occurs in children, whereas wheat-dependent exercise-induced anaphylaxis (WDEIA) mainly occurs in adults. The major allergens in wheat are gliadins and glutenins, which account for almost 86% of the total wheat proteins. In particular, wheat ω-5 gliadin and a high-molecular-weight glutenin subunit (HMW glutenin) are the most potent antigens for WDEIA, and certain tandem sequencing sites with glutamine residues have been identified as the primary structure of IgE-binding epitopes. QQFPQQQ, QQIPQQQ, and QQLPQQQ are the major epitope sequences of gliadin, a peptide (QQFPQQQIPQQQLPQQQ) was used to develop antiserum in rabbits.
The reactivity of QQIPQQQ, one of the major epitope peptides of gliadin, was the highest among the 117-mer overlapping peptides synthesized, its inhibition rate being approximately 42%. The rabbit anti-gliadin-epitope antibody showed reactivity similar to that of the wheat-allergy patients’ serum, and the inhibition rate by DG was lower than that by UG. The oral administration of UG after sensitization with it greatly enhanced intestinal permeability of HRP. The level of epitope in the blood absorbed from the small intestine was much higher for mice orally administered UG after sensitization with it than for those orally administered DG or water. Oral administration of UG after sensitization with it significantly enhanced the level of gliadin-specific IgE in the blood, whereas that of DG scarcely changed it.
The percentage of FcεRI+ and c-kit+ cells in the UG-sensitized orally administered UG group was much higher than in any of the other groups, being approximately 20% of total cells.
The level of total histamine in the small intestines in the UG-sensitized, orally administered UG group was almost double that in the other groups, whereas the level for the UG-sensitized, orally administered DG group was almost the same as for the unsensitized and control groups. The free histamine level in the serum of mice orally administered DG was lower than that of the mice orally administered UG, though there was no significant difference between the two groups.
