Celiac.com 04/24/2009 - Currently, one of the more promising areas of celiac disease research looks to be in peptide-based therapies. One of the keys to creating an effective peptide-based therapy for celiac disease lies in identifying the gluten peptides that trigger intestinal T cell responses when people with celiac disease consume wheat, rye, or barley.
A team of Italian researchers recently set out to do just that. The team was made up of A. Camarca, R.P. Anderson, G. Mamone, O. Fierro , A. Facchiano, S. Costantini, D. Zanzi, J. Sidney, S. Auricchio, A. Sette, R. Troncone, and C. Gianfrani. Their efforts were supported by the Institute of Food Sciences-National Research Council, Avellino, Italy. Their research carries strong implications for a peptide-based therapy in celiac disease
Presently, several gluten peptides are known to be active in celiac disease. The identification of additional gluten peptides eliciting intestinal T cell responses is critical for designing a successful peptide-based immunotherapy for celiac disease.
In their study, the research team assessed the recognition profile of gluten immunogenic peptides in adult HLA-DQ2(+) celiac patients. They did so by creating several lines of polyclonal, gliadin-reactive T cells from jejunal mucosa. They then tested for both proliferation and IFN-gamma production in reaction to 21 peptides from wheat glutenins and alpha-, gamma-, and omega-gliadins. They then conducted a magnitude analysis of the IFN-gamma responses to determine the spectrum of individual peptide activity, and to rank them accordingly.
Notably, 12 of the 14 patients responded to a different array of peptides. All alpha-gliadin stimulatory peptides mapped the 57-89 N-terminal region, thus affirming the importance of the known polyepitope 33-mer, although only 50% of subjects recognized 33-mer.
By contrast, 11 of 14 celiac subjects, nearly 80%, responded to gamma-gliadin peptides. A 17-mer variant of 33-mer, QLQPFPQPQLPYPQPQP, posessing only a single copy of DQ2-alpha-I and DQ2-alpha-II epitopes, displayed the same potency as 33-mer in triggering intestinal T cell responses.
One particular peptide from omega-gliadin, QPQQPFPQPQQPFPWQP, though structurally related to the alpha-gliadin 17-mer, is a separate epitope and activated in 5 out of 14 subjects.
The team's data reveal that intestinal T cells respond to a wide array of peptides, and that this heterogeneity emphasizes the relevance of gamma- and omega-gliadin peptides in celiac disease pathogenesis. Their findings indicate that, in DQ2(+) celiac patients, the most active gluten peptides are alpha-gliadin (57-73), gamma-gliadin (139-153), and omega-gliadin (102-118).
J Immunol. 2009 Apr 1;182(7):4158-66.