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Using Caco-2 Cells to Study Lipid Transport by the Intestine
Published on: August 20, 2015
Alpha-tocopheryl acetate is absorbed and hydrolyzed by Caco-2 cells comparative studies with alpha-tocopherol
Lydie Brisson1, Stéphane Castan, Hervé Fontbonne
1BiosCiences FRE CNRS 3005-Université Paul Cézanne-Aix Marseille III, Case 342, Faculté des Sciences et Techniques de Saint Jérôme, 13397 Marseille, France.
Chemistry and Physics of Lipids
|May 20, 2008
Summary
Alpha-tocopheryl acetate (Tac) absorption in Caco-2 cells mirrors alpha-tocopherol (Tol) absorption, suggesting protein-mediated transport. Tac hydrolysis occurs before or during absorption, with Caco-2 cells showing significant activity.
Area of Science:
- Cell biology
- Nutritional science
- Biochemistry
Background:
- Alpha-tocopherol (Tol) is a vital nutrient, but its absorption mechanisms, especially for its esterified form, alpha-tocopheryl acetate (Tac), require further elucidation.
- Caco-2 cell monolayers serve as a validated in vitro model for studying intestinal nutrient absorption and transport.
- Understanding the differential absorption and metabolism of vitamin E forms is crucial for nutritional and pharmacological applications.
Purpose of the Study:
- To compare the absorption and transport of alpha-tocopherol (Tol) and alpha-tocopheryl acetate (Tac) in Caco-2 cells.
- To investigate the role of bile salts and cellular hydrolysis in the absorption of Tol and Tac.
- To elucidate the transport mechanisms involved in the intestinal uptake of these vitamin E forms.
Main Methods:
- Utilized Caco-2 cell monolayers as an in vitro model system.
- Investigated the absorption of Tol and Tac solubilized in sodium taurocholate (NaTC) and oleic acid micelles.
- Analyzed dose-response relationships to infer transport mechanisms and assessed basolateral secretion and intracellular hydrolysis.
Main Results:
- Surprisingly, alpha-tocopheryl acetate (Tac) uptake was comparable to alpha-tocopherol (Tol) uptake.
- Both Tol and Tac uptake exhibited dose-response characteristics suggesting involvement of protein-mediated transport.
- Tac underwent significant hydrolysis either before absorption or intracellularly within Caco-2 cells, while Tol did not.
- Solubilization by sodium taurocholate (NaTC) is essential for uptake, with Tac requiring higher NaTC concentrations than Tol.
- Caco-2 cells possess inherent hydrolytic activity towards Tac, potentially enhanced by uptake of cholesterol esterase.
Conclusions:
- The absorption pathway for alpha-tocopheryl acetate (Tac) in enterocytes is distinct from, yet shares similarities with, alpha-tocopherol (Tol) absorption, involving protein-mediated transport.
- Hydrolysis of alpha-tocopheryl acetate (Tac) is a critical step, occurring either extracellularly or intracellularly, before or during its absorption.
- Sodium taurocholate (NaTC) is crucial for solubilizing both forms, facilitating their uptake across the apical membrane of Caco-2 cells.
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