Antagonists and non-toxic variants of the dominant wheat gliadin T cell epitope in coeliac disease.
BACKGROUND
Coeliac disease (CD) is due to an inappropriate T cell mediated response to specific gluten peptides. Measured by interferon gamma (IFN-gamma) ELISPOT, about half of the gliadin specific T cells induced with in vivo wheat gluten exposure in HLA-DQ2+ CD are specific for an alpha/beta-gliadin peptide (p57-73 QE65; QLQPFPQPELPYPQPQS) that includes two overlapping T cell epitopes (PFPQPELPY and PQPELPYPQ).


OBJECTIVE
To define minimally substituted variants of p57-73 QE65 universally devoid of IFN-gamma stimulatory capacity but capable of antagonising IFN-gamma secretion from polyclonal T cells specific for p57-73 QE65.


METHODS
Peripheral blood mononuclear cells collected from 75 HLA-DQ2+ CD patients after in vivo gluten challenge were used in overnight ELISPOT assays to screen 218 single or double substituted variants of p57-73 QE65 for cytokine stimulatory and antagonist activity.


RESULTS
The region p60-71 (PFPQPELPYPQP) and especially p64-67 (PELP) was sensitive to substitution. Twelve substitutions in p64-67 stimulated no IFN-gamma ELISPOT response. Among 131 partial agonists identified, 45 produced statistically significant inhibition of IFN-gamma ELISPOT responses when cocultured in fivefold excess with p57-73 QE65 (n = 10). Four substituted variants of p57-73 QE65 were inactive by IFN-gamma ELISPOT but consistently antagonised IFN-gamma ELISPOT responses to p57-73 QE65, and also retained interleukin 10 stimulatory capacity similar to p57-73 QE65.


CONCLUSIONS
Altered peptide ligands of p57-73 QE65, identified using polyclonal T cells from multiple HLA-DQ2+ CD donors, have properties in vitro that suggest that a single substitution to certain alpha/beta-gliadins could abolish their capacity to stimulate IFN-gamma from CD4 T cells and also have anti-inflammatory or protective effects in HLA-DQ2+ CD.
Anderson
R P
RP
Autoimmunity and Transplantation Division, Walter and Eliza Hall Institute, Department of Gastroenterology, The Royal Melbourne Hospital, Parkville, Victoria, Australia. banderson@wehi.edu.au
van Heel
D A
DA
Tye-Din
J A
JA
Jewell
D P
DP
Hill
A V S
AV
D000328:Adult; D000368:Aged; D000596:Amino Acids / Q000276:immunology; D002446:Celiac Disease / Q000276:immunology*; D002478:Cells, Cultured; D016207:Cytokines / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D018984:Epitopes, T-Lymphocyte / Q000276:immunology*; D005260:Female; D005903:Gliadin / Q000037:antagonists & inhibitors / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D014908:Triticum / Q000276:immunology*
D000596:Amino Acids; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D010446:Peptide Fragments; C509945:gliadin peptide 57-73 QE65; D007371:Interferon-gamma; D005903:Gliadin