Food-Derived Hemorphins Cross Intestinal and Blood–Brain Barriers In Vitro

Abstract

A qualitative study is presented, where the main question was whether food-derived hemorphins, i.e., originating from digested alimentary hemoglobin, could pass the intestinal barrier and/or the blood–brain barrier (BBB). Once absorbed, hemorphins are opioid receptor (OR) ligands that may interact with peripheral and central OR and have effects on food intake and energy balance regulation. LLVV-YPWT (LLVV-H4), LVV-H4, VV-H4, VV-YPWTQRF (VV-H7), and VV-H7 hemorphins that were previously identified in the 120 min digest resulting from the simulated gastrointestinal digestion of hemoglobin have been synthesized to be tested in in vitro models of passage of IB and BBB. LC-MS/MS analyses yielded that all hemorphins, except the LLVV-H4 sequence, were able to cross intact the human intestinal epithelium model with Caco-2 cells within 5–60 min when applied at 5 mM. Moreover, all hemorphins crossed intact the human BBB model with brain-like endothelial cells (BLEC) within 30 min when applied at 100 µM. Fragments of these hemorphins were also detected, especially the YPWT common tetrapeptide that retains OR-binding capacity. A cAMP assay performed in Caco-2 cells indicates that tested hemorphins behave as OR agonists in these cells by reducing cAMP production. We further provide preliminary results regarding the effects of hemorphins on tight junction proteins, specifically here the claudin-4 that is involved in paracellular permeability. All hemorphins at 100 µM, except the LLVV-H4 peptide, significantly decreased claudin-4 mRNA levels in the Caco-2 intestinal model. This in vitro study is a first step toward demonstrating food-derived hemorphins bioavailability which is in line with the growing body of evidence supporting physiological functions for food-derived peptides.

Production of Bioactive Peptides by Lactobacillus Species: From Gene to Application

“…Such sequences are inactive when present in the parental protein, but can be released after protein hydrolysis during gastro-intestinal digestion (GID), in vitro enzymatic hydrolysis, or microbial fermentation ( Korhonen and Pihlanto, 2006 ; Korhonen, 2009 ). The BAPs display interesting biological functions such as angiotensin converting enzyme (ACE) inhibition, mineral binding, antidiabetic, satiating, immunomodulating, opioid, antioxidant, or antimicrobial activities ( Nongonierma and FitzGerald, 2015 ; Park and Nam, 2015 ; Caron et al, 2017 ; Nielsen et al, 2017 ; Domenger et al, 2018 ). Research on BAPs provides insightful information on the impact of dietary proteins on health.…”

New Bioactive Peptides Identified from a Tilapia Byproduct Hydrolysate Exerting Effects on DPP-IV Activity and Intestinal Hormones Regulation after Canine Gastrointestinal Simulated Digestion

“…Other studies showed that certain DPP-IV inhibitory peptides were able to cross the IB in vitro. Domenger et al showed that among five DPP-IV inhibitory peptides identified in a bovine hemoglobin intestinal digest, only three of them were recovered intact after the passage through a Caco-2 cells monolayer [ 44 , 56 ]. Lacroix et al, also evidenced the susceptibility of certain milk protein-derived DPP-IV inhibitory peptides to be cleaved by brush barrier peptidases [ 57 ].…”

Current Evidence on the Bioavailability of Food Bioactive Peptides

“…Dalziel et al found that whey protein concentrates decreased motility in the colon, while their corresponding hydrolyzates increased the frequency of contrations [ 25 ]. Domenger and coworkers reported that hemorphins, a group of opioid peptides encrypted in the beta-chain of hemoglobin, specifically, LLW-YPWT, LW-YPWT, W-YPWT, W-YPWTQRF, and YPWTQRF had effects on intestinal peristalsis, appetite, and food intake regulation [ 26 ].…”