New-Level Insights into the Effects of Grape Seed Polyphenols on the Intestinal Processing and Transport of a Celiac Disease Immunodominant Peptide

The effect of three dietary tannins (procyanidin B3, B6, and T2) on the bioavailability of the 32-mer gliadin-derived immunogenic peptide was evaluated. An enterocyte-like Caco-2 cell line was used to mimic the epithelial transport of the 32-mer peptide, which was modeled by kinetic parameters with a mass spectrometry approach. The hydrolysis pattern on the enterocytes was analyzed, and the released peptides were quantified during the assay. The transport flux was dose-dependent. Along with procyanidin T2 and B6, procyanidin B3 promoted a significant inhibition mainly at the 100 μM peptide concentration. The hydrolysis efficiency was affected by procyanidins, while the cleavage pattern was suggested to be promoted by brush-border membranes at the apical compartment. The ability of procyanidins to molecularly bind to immunogenic peptides able to induce an adaptive response arose as a mechanism able to modulate their bioavailability, bioaccesibility, and further T CD4+ cell activation and expansion in a celiac disease (CD) model.