In vitro Hydrolysis of Gliadin and Casein Peptides: Secondary Defect in Coeliac Disease Shown by Organ Culture

Abstract

Background: Small-intestinal organ culture was used as an in vitro model of coeliac disease, studying biopsy specimens from patients with coeliac disease, cow's milk allergy, and controls. Methods: Organ culture incubations were done using the pure gliadin peptide B3144 (amino acid sequences 3–56 of α-type gliadins) and a control peptide from casein (amino acid sequences 152–193 of αs1-casein). The importance of using negative controls was stressed by non-specific tissue damage. By reversed-phase high-performance liquid chromatography of organ culture supernatants, 27 specimens were further investigated. Results: There was good retrieval of peptide calibration peaks after culture. Qualitative and quantitative evaluation of chromatography runs showed degradation of at least 29% of B3144 and 37% of Cas-P. Normal mucosa (controls and coeliac patients on a gluten-free diet) was able to hydrolyse peptide fractions completely, whereas incubation with damaged mucosa (coeliac disease, cow's milk allergy) left initial peptides. Conclusion: It is concluded, using a pure single gliadin peptide, that deficient peptide hydrolysis in coeliac disease was a secondary event.

Key Words:

• Coeliac disease
• gliadin and casein peptides
• high-performance liquid chromatography
• small-intestinal organ culture