RT Journal Article SR Electronic T1 Mechanisms of epithelial translocation of the α2-gliadin-33mer in coeliac sprue JF Gut JO Gut FD BMJ Publishing Group Ltd and British Society of Gastroenterology SP 747 OP 754 DO 10.1136/gut.2007.136366 VO 57 IS 6 A1 M Schumann A1 J F Richter A1 I Wedell A1 V Moos A1 M Zimmermann-Kordmann A1 T Schneider A1 S Daum A1 M Zeitz A1 M Fromm A1 J D Schulzke YR 2008 UL http://gut.bmj.com/content/57/6/747.abstract AB Background and aims: The α2-gliadin-33mer has been shown to be important in the pathogenesis of coeliac disease. We aimed to study mechanisms of its epithelial translocation and processing in respect to transcytotic and paracellular pathways. Methods: Transepithelial passage of a fluorescence-labelled α2-gliadin-33mer was studied in Caco-2 cells by using reverse-phase high-performance liquid chromatography, mass spectrometry, confocal laser scanning microscopy (LSM) and fluorescence activated cell sorting (FACS). Endocytosis mechanisms were characterised with rab-GFP constructs transiently transfected into Caco-2 cells and in human duodenal biopsy specimens. Results: The α2-gliadin-33mer dose-dependently crossed the epithelial barrier in the apical-to-basal direction. Degradation analysis revealed translocation of the 33mer polypeptide in the uncleaved as well as in the degraded form. Transcellular passage was identified by confocal LSM, inhibitor experiments and FACS. Rab5 but not rab4 or rab7 vesicles were shown to be part of the transcytotic pathway. After pre-incubation with interferon-γ, translocation of the 33mer was increased by 40%. In mucosal biopsies of the duodenum, epithelial 33mer uptake was significantly higher in untreated coeliac disease patients than in healthy controls or coeliac disease patients on a gluten-free diet. Conclusion: Epithelial translocation of the α2-gliadin-33mer occurs by transcytosis after partial degradation through a rab5 endocytosis compartment and is regulated by interferon-γ. Uptake of the 33mer is higher in untreated coeliac disease than in controls and coeliac disease patients on a gluten-free diet.