Optimization of an in vitro model of co-culture cells to study the effect of food grade emulsifiers on intestinal physiology
Merian NASSRA, Patrick SAUVANT and Claude ATGIE
Colloïdes et Lipides pour l'Industrie et la Nutrition
CBMN, UMR 5248-CNRS, Bordeaux University
Increaseduse of synthetic emulsifiers to stabilize lipids emulsion in processed industrial food is more and more associated with an increase development of nutritional diseases. The alteration of intestinal permeabilityinducedby emulsifiers is today clearly demonstrated.Consequently altered exchange of many compounds, with nutritional interest or not, through gut mucosa,is often pointed out by researchers as a cause for the development of numerous diseases [1-2]. Nevertheless, molecular and cellular mechanisms involving food grade emulsifiers in the modification of gut permeability are not yet fully elucidated.
Our main objective is to better understand how commonly used food grade emulsifiers could modulate nutrients absorption at the intestinal epithelial level.
To achieve our goal, we have developed and validatedin the laboratory an in vitro model of intestinal barrier. Our model is based on a co-culture system of Caco-2/TC7 and HT-29-MTX (1:9 ratio), which is recognized as a soundandconvenient model that closely mimic the permeability features of the human intestinal barrier [3-4].The co-cultures were first characterized in term of permeability withtransepithelial electrical resistance measurements, transport studies using marker molecules for the paracellular route as well asfor the mucus production were also performed.
Secondly, a micellar system to deliver lipids toour co-culture model has been validated.Mixed micelles were formed from oleic acid, sodium taurocholate, cholesterol,monooleinand phospholipids [5]. We find that the CMC value for sodium taurocholate is3.5mMand that this dose had no cytotoxic effecton our cells. Furthermore size and stability of our micelles was determined, a diameter of 30nm and a stability of our micelles 3 days at 4°C and 4 weeks at -80°C have been clearly established.
The cytotoxicity threshold was determined on our cell model for Tween 80, sodium stearoyl-2-lactylate known as SSL and beta-lactoglobulin, sodium caseinate.Tween 80 could be used safely at0.01%,0.005%, SSLat 0.005%, 0.0005%, beta-lactoglobulin at 0.05%, 0.005% and sodium caseinate at 0.5%, 0.01% for respectively 6 or 24 hours of treatment.These concentrations did not also alter the cell layer permeability. These findings demonstrate that naturals emulsifiers like caseinate or beta lactoglobulinare less toxic for our intestinal barrier model than synthetics ones like SSL or Tween 80.
In the future, we planned to investigate the effects of synthetic food grade emulsifiersused in the food industry on the integrity of the intestinal barrier and consequently on lipid absorption.
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[2] Csáki K. F (2011) Med. Hypotheses. 76, 676-681.
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[4] Araújo F. and Sarmento B (2013)Int. J. Pharm. 458, 128-134.
[5]A. Goncalves et al(2013) J. Nutr. Biochem. 24, 1751-1757.