Utilizing High Throughput Discovery Approach to Identify Optimal Candidate Deamidated Gliadin Peptides for the Identification of Celiac Disease.

In recent years it has become more frequent for physicians to come across types of gluten sensitivity other than celiac disease (CD). Regardless of the absence of any serological CD markers or intestinal damage, gluten sensitive (GS) patients often report intestinal and extraintestinal symptoms shortly after the ingestion of gluten and the disappearance of such symptoms on a gluten free diet (GFD). Regrettably, at present, there is no evidence of any mucosal or serological modifications in GS patients, or that gluten is really the trigger factor in gluten sensitivity. We aimed at evaluating the impact of gliadin challenge on two experimental settings, i.e. in vitro gliadin challenge of duodenal mucosa and peripheral blood basophils in GS patients compared to CD patients and healthy controls. We consecutively enrolled patients referred to tertiary centers for food intolerance and celiac disease. Participants underwent a complete clinical screening in order to rule out CD (serum a-tTG, EMA, total IgA and HLA status, where appropriate), an interview for evaluation of diet and symptoms, a skin prick test to exclude wheat allergy, upper endoscopy for duodenal biopsies used for both histological assessment and for the in vitro evaluation of the gliadin-induced mucosal expression of early and late inflammatory markers: PY99, epithelial HLA-DR, ICAM1, crypt HLA-DR, CD3, CD25 and CD69. In addition, a basophils activation assay, in which patients' basophils were challenged with a gliadin extract, was performed. Basophils were analyzed for the expression of hematopoietic membrane antigens CD203c, CD63 and CD45 by flow cytometry looking at differences in antigen expression. 119 subjects were screened for CD and GS and, according to the results, four groups were obtained: GS patients (no.16), CD on gluten free diet (no.34), CD on gluten containing diet (no.35) and healthy controls (no.34). As for the in vitro gliadin challenge, all CD patients, regardless of their dietetic status, showed a clear mucosal activation (increased immunofluorescence intensity both for early and delayed inflammation markers) when stimulated with gliadin, while only 3 controls and 3 GS patients showed an weak response for some, not all, inflammation markers. Also, there were no significant differences in the skin prick test results or in the level of CD63 and CD203c basophils expression, used as a marker of cell activation, among the groups. The present study shows that in GS patients, gliadin challenge test did not show any significant modifications in the expression of those mucosal inflammation markers found increased in CD patients. Therefore, this tool should not be used as a diagnostic instrument in case of GS. Moreover, the lack of differences in basophils activation and skin prick test seems to exclude this form of cellular sensitivity in our GS series also.