Intranasal administration of one alpha gliadin can downregulate the immune response to whole gliadin in mice

The mucosal lesion present in coeliac disease is an immune-mediated injury triggered by gliadin and restricted by a particular assortment of major histocompatibility complex genes. In view of this, an immunomodulatory approach that induces tolerance to this antigen appears to be a possible alternative to a strict gluten-free diet in treating coeliac disease. We have shown that intranasal administration of multiple doses of whole gliadin is required to specifically inhibit T helper 1-like T-cell reactivity in BALB/c mice immunized parenterally with whole gliadin. However, T-cell activation to multiple antigens, as a consequence of the chemical complexity shown by the antigen gliadin, could hamper efforts to identify single component(s) useful for tolerance induction. In this study, gliadin fractions were purified and administered intranasally to study their ability to induce tolerance to whole gliadin in our animal model. We found that the alpha fraction was particularly effective in downregulating both the in vitro gliadin-specific T-cell proliferation and interferon-gamma production to whole gliadin. In particular, a purified alpha -gliadin was able to suppress the immune response to the entire gliadin mixture. These results demonstrate how an immune response to a complex antigen may be controlled by treatment with a purified component and specifically indicate alpha -gliadin to be a good candidate for further identification of short peptides to be used as tolerogens in this model.