Transport across Caco-2 monolayers of peptides arising from in vitro digestion of bovine milk proteins

The entire panel of peptides produced from caseins (CN) and whey proteins (WP) that survive in vitro sequential gastro-pancreatic digestion and translocate across monolayers of Caco-2 cells, used as a model of the intestinal epithelium, has been characterised by HPLC and mass spectrometry. Among the milk-derived bioactive peptides, only minor amounts of mono-phosphorylated peptides arising from alpha(s)1- and beta-CN were detected. The absorption behaviour of two resistant beta-lactoglobulin (beta-Lg) domains, beta-Lg 125-135 and beta-Lg 40-60, was studied in detail using synthetic peptides. The IgE-binding properties of the digests recovered from the apical and basolateral monolayer compartments were evaluated by dot-blot, using the sera of milk allergic children (N = 5). Outcomes indicated beta-Lg 127-135 as a possible "immune sensitising factor" in vivo. The almost complete loss of the IgE-affinity of CN and WP after digestion points out the need to design in vivo experiments to track the metabolic fate of dietary proteins. (c) 2013 Elsevier Ltd. All rights reserved.