Effect of β-lactoglobulin hydrolysate and β-lactorphin on intestinal mucin secretion and gene expression in human goblet cells

A hydrolysate obtained from a whey protein concentrate rich in beta-lactoglobulin has been shown to stimulate mucin secretion and mucin 5AC gene expression in human intestinal goblet cells HT29-MTX. Mass spectrometry-based peptidomic analysis allowed the identification of the peptides contained in the hydrolysate. None of them had the required structure to bind opioid receptors, except for the sequence YLLF, corresponding to beta-lactorphin. The exposure of the cells to synthetic beta-lactorphin evoked a mucin secretory effect although no change in the mucin gene expression was observed. The amidated homolog of this peptide, which has been reported as a more potent opioid, induced mucin gene expression after incubation for 4 h. This supports the hypothesis that induction of the mucin secretory response can be mediated by mu-opioid receptors in HT29-MTX cells, although other mechanisms responsible for the hydrolysate activity cannot be excluded. Protein hydrolysates with the ability to induce mucin secretion could be promising for improving gastrointestinal protection. (C) 2012 Elsevier Ltd. All rights reserved.