Allergenicity of Deamidated and/or Peptide-Bond-Hydrolyzed Wheat Gliadin by Transdermal Administration (1)
Regarding patients with wheat-dependent, exercise-induced anaphylaxis (WDEIA), certain tandem sequencing sites with glutamine residues in gluten and gliadin, such as QQQPP, QQIPQQQ, QQLPQQQ, QQFPQQQ, QQSPEQQ, QQSPQQQ, QQYPQQQ, and PYPP, have been identified as the primary structure of immunoglobulin (Ig) E-binding epitopes.
Because the sera from patients who used facial soap containing acid-treated gluten reacted with QPQQPFPQ in gliadin structure and its deamidated sequence PEEPFP, hydrolyzed and/or deamidated gliadin in gluten would be the main allergen for cutaneous sensitization.
Hydrolyzed and deamidated gliadin (HDG) was prepared by heating 15 mg/mL UG in 0.1 N HCl at 100 ◦C for 1 h. The reaction was quenched by cooling and adding the same volume of 0.1 N NaOH and 0.1 M phosphate buffer at pH 7.4, and the resulting solution was lyophilized to obtain HDG.
The degrees of deamidation of UG, DG, HG, and HDG were 0%, 26%, 0%, and 39%, respectively, while those of peptide-bond hydrolysis of UG, DG, HG, and HDG were 0%, 100 kDa) and low- (<10 kDa) molecular-weight peptides and the range of molecular weight was widely distributed.
The average rectal temperature of HDG-sensitized mice decreased by approximately 4.2C for 30 min. Severe symptoms were observed in HDG-sensitized mice, with an average score of 4.
The mean value of plasma histamine level of HDG-sensitized mice was significantly higher than that of UG-, DG- and HG-sensitized mice HG-sensitized mice and unsensitized mice (p < 0.05).
The IgE and IgG1 levels of HDG-sensitized mice were increased compared with those of unsensitized mice (p < 0.05).
The Mcpt8 mRNA expression level increased in the HG and HDG groups but not in the other groups. The mRNA expression levels of CD86 in the HDG group was 1.8-fold higher than that in the DW group.
HG and HDG were recognized as antigens by basophils, but UG and DG were not recognized and the sensitizing abilities of UG and DG were lower than those of HG and HDG. The glutamic acid residues in gliadin may play an important role in activating dendritic cells and inducing allergic reactions after permeation through skin.
1. R. Abe, N. Matsukaze, H. Kobayashi, Y. Yamaguchi, H. Uto-Kondo, H. Kumagai, H. Kumagai, Allergenicity of Deamidated and/or Peptide-Bond-Hydrolyzed Wheat Gliadin by Transdermal Administration. Foods. 9 (2020), doi:10.3390/foods9050635.