Induction of apoptosis in Caco-2 cells by wheat gliadin peptides

Recent experimental evidence suggests that enterocyte apoptosis is greater than hitherto assumed and may be responsible for villous atrophy in coeliac disease. We have previously demonstrated that a small peptide (M.W. 1157.5 Da), identified as the sequence H2N-gln-gln-pro-gln-asp-ala-val-gln-pro-ph e-COOH from durum wheat gliadin, is able to prevent K 562 (S) cell agglutin ation induced by the peptic-tryptic digests (PT) of prolamin fractions from the cereals which are not tolerated in coeliac disease (i.e. bread wheat, rye, barley and possibly oats), and toxic A-gliadin peptides in coeliac dis ease. In the present study we have investigated the effects of the bread wh eat gliadin digest (PT) on apoptosis of Caco-2 cells and whether the '1157. 5' Da peptide may in any way interfere with them. We evaluated both earlier biochemical and later morphological nuclear apoptotic events in the human colon adenocarcinoma cell line Caco-2. After 48 h exposure to the PT gliadi n digest and the '1157.5' Da peptide, apoptosis was detected both for the e arly-stage apoptotic cells (adherent cells) and the late-stage apoptotic on es (detached cells which were floating in the culture medium). Exposure to the PT gliadin digest resulted in a high percentage of adherent cells that underwent cell death by apoptosis (about 30%), independent of the concentra tion range used; while the presence in the culture medium of peptide '1157. 5' Da determined complete inhibition of cell death. On the other hand. morp hological nuclear modifications observed in the floating cells showed a dif ference in the rate of the apoptosis dependent on the PT concentration, wit h partial protection in the presence of the peptide. These findings show an action of bread wheat gliadin peptides leading to cell death by apoptosis in the Caco-2 cell line and that the '1157.5' Da peptide is capable of prev enting such an effect. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.