Transamidation of wheat flour inhibits the response to gliadin of intestinal T cells in celiac disease.
OBJECTIVE
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 alpha-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 gamma 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.
Gianfrani
Carmen
C
Institute of Food Sciences, CNR, Avellino, Italy.
Siciliano
Rosa A
RA
Facchiano
Angelo M
AM
Camarca
Alessandra
A
Mazzeo
Maria F
MF
Costantini
Susan
S
Salvati
Virginia M
VM
Maurano
Francesco
F
Mazzarella
Giuseppe
G
Iaquinto
Gaetano
G
Bergamo
Paolo
P
Rossi
Mauro
M
D000293:Adolescent; D000328:Adult; D000588:Amines / Q000378:metabolism; D001706:Biopsy; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D002446:Celiac Disease / Q000188:drug therapy / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D005903:Gliadin / Q000009:adverse effects / Q000276:immunology / Q000378:metabolism*; D006683:HLA-DQ Antigens / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000276:immunology*; D008738:Methyl Ethers / Q000494:pharmacology / Q000627:therapeutic use; D008875:Middle Aged; D013379:Substrate Specificity; D011503:Transglutaminases / Q000494:pharmacology / Q000627:therapeutic use; D014908:Triticum / Q000378:metabolism*
D000588:Amines; D006683:HLA-DQ Antigens; C053186:HLA-DQ2 antigen; D008738:Methyl Ethers; D007371:Interferon-gamma; D005903:Gliadin; D011503:Transglutaminases