Two prolamin peptides from durum wheat preclude celiac disease-specific T cell activation by gluten proteins

Celiac disease (CD) is a permanent intolerance to wheat prolamins and related proteins displayed by genetically susceptible individuals. Blocking or modulation of CD-specific T cell response by altered prolamin peptides are currently considered as a potential alternative to the only effective therapy of CD based on a life-long gluten-free diet. Two prolamin peptides, the 9-mer ASRVAPGQQ and the 10-mer GTVGVAPGQQ sequences, were identified by mass spectrometry in the peptic/tryptic digest of prolamins (PTP) from durum wheat (Triticum turgidum ssp. durum) cv. Adamello, and investigated for their ability to preclude the stimulation of CD-specific mucosal T cells by gluten proteins. Gluten-specific polyclonal intestinal T cell lines from five CD children (mean age 5 years) were exposed to 50 mu g/ml of a deamidated PTP from whole flour of common wheat (T. aestivum) cv. San Pastore, and tested for proliferation and production of interferon-gamma (INF-gamma) and interleukin 10 (IL-10). The same experiment was performed in the presence of 20 mu g/ml of the 9-mer or the 10-mer peptide. T cells exposed to PTP showed a threefold increase in proliferation and INF-gamma production, and a significant (P a parts per thousand currency sign 0.05) reduction in IL-10 secretion as compared with control cells incubated with the culture medium. Addition of either the 9-mer or the 10-mer peptide to PTP downregulated T cell proliferation and INF-gamma production, and caused a significant (P a parts per thousand currency sign 0.05) increase in IL-10 secretion. The T cell reactivity elicited by PTP is precluded by both the 9-mer and the 10-mer sequence, suggesting that over-expression of these proteolytically stable peptides may result in a wheat flour with reduced toxicity for CD patients.