title: Epithelial transport of immunogenic and toxic gliadin peptides in vitro.
abstract: METHODS
  Celiac 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.
  
  
  RESULTS
  Fluorescence 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.
  
  
  CONCLUSIONS
  Considering 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.
authors.affiliation: Department of Pediatrics, Justus Liebig University Giessen, Feulgenstr. 12, D-35392, Giessen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Zimmermann
authors.affiliation: Department of Pediatrics, Justus Liebig University Giessen, Feulgenstr. 12, D-35392, Giessen, Germany; Institute of Nutritional Science, Justus Liebig University Giessen, Wilhelmstr. 20, D-35392, Giessen, Germany.
authors.forename: Silvia
authors.initials: S
authors.lastname: Rudloff
authors.affiliation: Institute of Biochemistry, Medical Faculty, Justus Liebig University Giessen, Friedrichstr. 24, D-35392, Giessen, Germany.
authors.forename: Günter
authors.initials: G
authors.lastname: Lochnit
authors.affiliation: Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 58, D-35392, Giessen, Germany.
authors.forename: Sevgi
authors.initials: S
authors.lastname: Arampatzi
authors.affiliation: Pharmaceutical and Medicinal Chemistry, Universität Hamburg, Bundesstr. 45, D-20146, Hamburg, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Maison
authors.affiliation: Department of Pediatrics, Justus Liebig University Giessen, Feulgenstr. 12, D-35392, Giessen, Germany.
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Zimmer
mesh_terms: D018938:Caco-2 Cells; D002446:Celiac Disease / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D020895:Enterocytes / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D005903:Gliadin / Q000493:pharmacokinetics* / Q000633:toxicity*; D006801:Humans; D010446:Peptide Fragments / Q000493:pharmacokinetics* / Q000633:toxicity*; D021381:Protein Transport / Q000187:drug effects
chemical_list: D010446:Peptide Fragments; C553138:gliadin peptide (31-43); D005903:Gliadin