Epithelial Transport of Immunogenic and Toxic Gliadin Peptides In Vitro

Abstract

ScopeCeliac disease is an autoimmune disorder caused by failure of oral tolerance against gluten in genetically predisposed individuals. The epithelial translocation of gluten-derived gliadin peptides is an important pathogenetic step; the underlying mechanisms, however, are poorly understood. Thus, we investigated the degradation and epithelial translocation of two different gliadin peptides, the toxic P31–43 and the immunogenic P56–68. As the size, and hence, the molecular weight of peptides might have an effect on the transport efficiency we chose two peptides of the same, rather short chain length.Methods and ResultsFluorescence labeled P31–43 and P56–68 were synthesized and studied in a transwell system with human enterocytes. Fluorometric measurements were done to reveal antigen translocation and flow cytometry as well as confocal microscopy were used to investigate cellular uptake of peptides. Structural changes of these peptides were analysed by MALDI-TOF-MS. According to fluorescence intensities, significantly more P31–43 compared to P56–68 was transported through the enterocyte layer after 24 h incubation. In contrast to previous reports, however, mass spectrometric data do not only show a time-dependent cleavage of the immunogenic P56–68, but we observed for the first time the degradation of the toxic peptide P31–43 at the apical side of epithelial cells.ConclusionConsidering the degradation of gliadin peptides by enterocytes, measurement of fluorescence signals do not completely represent translocated intact gliadin peptides. From our experiments it is obvious that even short peptides can be digested prior to the translocation across the epithelial barrier. Thus, the chain length and the sensibility to degradations of gliadin peptides as well as the integrity of the epithelial barrier seem to be critical for the uptake of gliadin peptides and the subsequent inflammatory immune response.

Involvement of cell surface TG2 in the aggregation of K562 cells triggered by gluten

“…This mechanism of selective activation would enable the remaining part of TG2 to remain preserved in the closed shape, still capable of activation but sheltered from the oxidant extracellular environment in which the open form undergoes rapid inactivation through formation of disulfide bridges between vicinal cysteines. It has been described that p31-43, entering the intestinal epithelial cells by endocytosis, can attain to the lamina propria by apical-to-basal passage (Zimmermann et al 2014) and promotes the migration of dendritic cells in this compartment (Chládková et al 2011). Further, it has also been described that epithelial junctional integrity is already compromised in the CD early stages, before the disease progresses to chronic enteropathy (Rauhavirta et al 2014), an event that permits to gluten to reach the lamina propria and take contact with professional APC, the dendritic cells, to be presented to naïve T-cells after processing.…”

Celiac disease‐associated Neisseria flavescens decreases mitochondrial respiration in CaCo‐2 epithelial cells: Impact of Lactobacillus paracasei CBA L74 on bacterial‐induced cellular imbalance

“…The colocalisation coefficient represents the weighted colocalisation coefficient of Ch1 (red) with respect to Ch2 (green) for each experiment (Araya et al, 2016;Zimmermann et al, 2014). Magnification of the micrographs was 63× objective, 2× zoom in all.…”

Gluten Immunogenic Peptides as Standard for the Evaluation of Potential Harmful Prolamin Content in Food and Human Specimen

“…However, the use of intestinal biopsies from celiac and control patients to investigate the transport and degradation of GIP involve a complex interplay between various cell types and hardly allows to reveal the role the enterocytes in the metabolic fate of GIP and thus their role in antigen transport and presentation. The transport in the gut epithelium of two gluten peptides and among them, the immunogenic P56-68 peptide as representative GIP, has been studied [51]. GIP transport and increased uptake depended on the chain length as well as the integrity of the epithelial barrier system [51].…”

“…The transport in the gut epithelium of two gluten peptides and among them, the immunogenic P56-68 peptide as representative GIP, has been studied [51]. GIP transport and increased uptake depended on the chain length as well as the integrity of the epithelial barrier system [51]. The absorption of gliadin peptides is complex.…”