Transamidation of Wheat Flour Inhibits the Response to Gliadin of Intestinal T Cells in Celiac Disease

Background & Aims: Celiac disease is characterized by activation of HLA-DQ2/DQ8–restricted intestinal gluten-specific CD4⁺ T cells. In particular, gluten becomes a better T-cell antigen following deamidation catalyzed by tissue transglutaminase. To date, the only available therapy is represented by adherence to a gluten-free diet. Here, we examined a new enzyme strategy to preventively abolish gluten activity. Methods: Enzyme modifications of the immunodominant α-gliadin peptide p56-68 were analyzed by mass spectrometry, and peptide binding to HLA-DQ2 was simulated by modeling studies. Wheat flour was treated with microbial transglutaminase and lysine methyl ester; gliadin was subsequently extracted, digested, and deamidated. Gliadin-specific intestinal T-cell lines (iTCLs) were generated from biopsy specimens from 12 adult patients with celiac disease and challenged in vitro with different antigen preparations. Results: Tissue transglutaminase–mediated transamidation with lysine or lysine methyl ester of p56-68 or gliadin in alkaline conditions inhibited the interferon γ expression in iTCLs; also, binding to DQ2 was reduced but not abolished, as suggested by in silico analysis. Lysine methyl ester was particularly effective in abrogating the activity of gliadin. Notably, a block in the response was observed when iTCLs were challenged with gliadin extracted from flour pretreated with microbial transglutaminase and lysine methyl ester. Conclusions: Transamidation of wheat flour with a food-grade enzyme and an appropriate amine donor can be used to block the T cell–mediated gliadin activity. Considering the crucial role of adaptive immunity in celiac disease, our findings highlight the potential of the proposed treatment to prevent cereal toxicity.

Abbreviations used in this paper: ANOVA, analysis of variance, IFN, interferon, IL, interleukin, iTCL, intestinal T-cell line, MALDI-TOF, matrix-assisted laser desorption-ionization time of flight, MS/MS, tandem mass spectrometry, mTG, microbial transglutaminase, PT-gliadin, peptic-tryptic digest of gliadin, tTG, tissue transglutaminase