Coeliac disease (CD) is caused by intolerance to gluten, a common food protein. The disease affects approximately one million Europeans. There is strong evidence that CD is the result of aberrant T cell responses to gluten peptides bound to the disease predisposing Human Leukocyte Antigen (HLA-DQ) molecules. T cell recognition of many of these peptides is dependant on them being enzymatically modified in a way that promotes their binding to HLA-DQ. These results provide a rationale for the development of CD. In this project, the relative importance of the identified peptides will be determined, an in vivo effect of these peptides will be demonstrated, the feasibility of therapeutic intervention will be investigated, and reliable and easy-to-handle test systems for the detection of toxic gluten peptides in food products will be developed.
Quantify and characterise the adult and paediatric T cell responses directed at the gluten peptides identified. HLA-DQ/peptide tetramer staining, ELI-spot assays and intracellular IFN gamma staining will be exploited to establish the overall frequency of gluten specific T cells in coeliac mucosa and to assess the importance of T cell recognition of deamidated vs. non-deamidated gluten epitopes. This will provide new insights into the mechanisms of disease pathology and offer invaluable data for the optimal design of an assay to detect 'toxic' components of gluten.
Formal evidence that the T cell epitopes are associated with the toxicity of gluten will be provided by conducting peptide feeding trials in human coeliac volunteers. It is possible that oral challenge with pre-deamidated peptides will re-route the peptides into the pathways that normally ensure tolerance to food antigens. Therefore, we will investigate what effect feeding deamidated gluten peptides has on peptide specific T cells. This, and other therapeutic strategies unethical to explore in human volunteers, will be investigated in a humanised transgenic mouse model of CD. This work will provide a foundation for initiating human clinical trials investigating new methods to treat CD.
Stable cell lines expressing transfected T cell receptors specific for the major gluten epitopes will be generated. These transfectants will form the basis of a test-kit that will detect the toxic components of wheat in food products. The specificity and sensitivity of these T cell reagents will then be compared with a panel of antibodies raised to the same peptide epitopes to see if ultimately an ELISA based system with a similar specificity can be developed.
A detailed description of the T cell response to wheat in CD will be provided, and the relative importance of the different gluten epitopes will be identified. An in vivo demonstration of the toxicity of these peptides will be provided. The specificity of T cell transfectants and monoclonal antibodies recognising the major gluten epitopes will be compared.
The knowledge and reagents from generated within this project will form the basis for a novel T cell based test-kit that will allow, for the first time, the direct detection of toxic gluten in food.