Impact of human milk pasteurization on digestive kinetics and intestinal lipid absorption using a combination of in vitro models
Résumé
Introduction
Human milk is a complex biological fluid recognized as the gold standard in neonatal nutrition,
especially for preterm infants since it supports growth and brain development. Donor human milk,
pasteurized for safety reasons, is the first option to feed preterm infants when mothers’ own milk is
not available.
Objective
The aim of the present study was to determine the impact of breastmilk pasteurization on preterm
gastrointestinal digestion and to evaluate its effect on lipid absorption.
Methodology
Kinetics of digestion and structural desintegration of pasteurized human milk (PHM) and raw human
milk (RHM) were evaluated using a static in vitro digestion model that we adapted to simulate
preterm digestion ability. Caco-2 /TC7 cells, an intestinal absorption model, were subsequently incubated
with diluted PHM vs RHM-digestion media.
Main findings
During in vitro digestion, proteolysis was evaluated by SDS-PAGE followed by densitometry. Lactoferrin
proteolysis was significantly (p<0.05) higher in PHM than in RHM in the gastric and intestinal
phases with 26±4 % and 53±18% of intact lactoferrin remaining at 60 min of intestinal digestion for
PHM and RHM, respectively. β-casein was less susceptible to pepsinolysis in PHM, with 78±3 %
remaining at 60 min of gastric digestion vs. 37±4% for RHM, but less than 5% remained at 60 min of
intestinal digestion for both milks. The lipolysis kinetics, determined by thin layer chromatography,
was not significantly different between RHM and PHM. In Caco-2 cells after 16h of incubation, cell
monolayer integrity assesses by occludine immunostaining was unaffected and intracellular lipid
droplets could be visible using Oil Red O staining. Triglyceride secretion measured in the basolateral
medium seems to be higher for RHM than PHM, supporting further exploration of the gene expression
involved in intestinal lipid absorption.
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