Evidence of increased gluten-induced perturbations in the nucleophilic tone and detoxifying defences of intestinal epithelial cells impaired by gastric disfunction.

It has been increasingly demonstrated over the past few years that some proteolytically resistant gluten peptides may directly affect intestinal cell structure and functions by modulating pro-inflammatory gene expression and oxidative stress. The relationship between oxidative cell damage and Celiac Disease (CD) is supported by several studies on human intestinal epithelial cell lines, such as the Caco-2 cell model, already shown to be particularly sensitive to the pro-oxidative and pro-apoptotic properties of gluten protein digests. Through providing valuable evidence concerning some of the pathophysiological mechanisms that may be at play in gluten-related disorders, most of these in vitro studies have been employing simplified digestion schemes and intestinal cell systems that do not fully resemble mature enterocytes in terms of their characteristic tight junctions, microvilli and membrane transporters. Herein the peptide profile and pro-oxidative effect of two different gastrointestinal gliadin digestions was thoroughly characterized and comprehensively compared: one following the complete INFOGEST workflow and a second one by-passing gastric processing, to assess the dependence of gliadin-triggered downstream cell effects on pepsin activity. In both matrices, gluten-derived immunogenic peptide sequences were identified by non-targeted LC-MS/MS. Altogether, this study provides first-hand data concerning the still unexplored peptide composition, gastric-dependence and immunogenicity of physiologically representative gliadin protein digests as well as foundational clues stressing the need for more complex and integrated in vitro cell systems when modelling and exploiting gluten-induced perturbations in the nucleophilic tone and inflammatory status of intestinal epithelial cells.