Fatty acids affect micellar properties and modulate vitamin D uptake and basolateral efflux in Caco-2 cells☆ , ☆☆ Aurélie Goncalves a,b,c,d , Béatrice Gleize a,b,c , Stéphanie Roi a,b,c , Marion Nowicki a,b,c , Amélie Dhaussy d , Alain Huertas d , Marie-Josèphe Amiot a,b,c , Emmanuelle Reboul a,b,c, ⁎ a INRA, UMR 1260 “Nutrition, Obesity and Risk of Thrombosis”, F-13385 Marseille, France b INSERM, UMR U1062, F-13385 Marseille, France c Aix-Marseille University, F-13385 Marseille, France d Lesieur, Asnières-sur-Seine, France Received 19 December 2012; received in revised form 15 March 2013; accepted 25 March 2013 Abstract We have recently shown that vitamin D 3 (cholecalciferol) absorption is not a simple passive diffusion but involves cholesterol transporters. As free fatty acids (FAs) modulate cholesterol intestinal absorption and metabolism, we hypothesized that FAs may also interact with vitamin D absorption. Effects of FAs were evaluated at different levels of cholecalciferol intestinal absorption. First, the physicochemical properties of micelles formed with different FAs were analyzed. The micelles were then administered to human Caco-2 cells in culture to evaluate FA effects on (i) cholecalciferol uptake and basolateral efflux and (ii) the regulation of genes coding proteins involved in lipid absorption process. Micellar electric charge was correlated with both FA chain length and degree of unsaturation. Long-chain FAs at 500 μM in mixed micelles decreased cholecalciferol uptake in Caco-2 cells. This decrease was annihilated as soon as the long- chain FAs were mixed with other FAs. Oleic acid significantly improved cholecalciferol basolateral efflux compared to other FAs. These results were partly explained by a modulation of genes coding for lipid transport proteins such as Niemann-pick C1-like 1 and scavenger receptor class B type I. The data reported here show for the first time that FAs can interact with cholecalciferol intestinal absorption at different key steps of the absorption process. Cholecalciferol intestinal absorption may thus be optimized according to oil FA composition. © 2013 Elsevier Inc. All rights reserved. Keywords: Bioavailability; Fatty acids; Cholecalciferol; Mixed micelles; Caco-2 TC-7 cells; Intestinal absorption 1. Introduction Vitamin D deficiency and insufficiency has widely been related to the development of several chronic diseases, especially cardiovascular diseases [1] such as hypertension [2], coronary heart disease and stroke [3]. Indeed, both sun exposure and vitamin D intake are not sufficient to reach an adequate vitamin D status in most people, and many studies have argued for the optimization of vitamin D status as a public health priority. It was long assumed that vitamin D, like any other fat-soluble (micro)nutrient, is absorbed by a passive process [4,5]. However, we recently showed that vitamin D 3 (cholecalciferol) intestinal absorp- tion involves membrane transporters including scavenger receptor class B type I (SR-BI), cluster determinant 36 (CD36) and Niemann- pick C1-like 1 (NPC1L1) [6]. These transporters (chiefly NPC1L1) have already been described to transport dietary cholesterol, which displays a structural homology with vitamin D, and we demonstrated that cholesterol could compete with cholecalciferol for its intestinal absorption [6,7]. Over 50 years of research has worked to define the impact of fatty acids (FAs) on cholesterol metabolism. Human feeding trials have shown that replacing dietary saturated FAs (5–7% of energy) with either monounsaturated FAs (MUFAs) [8,9] or polyunsaturated FAs (PUFAs) [10,11] significantly decreased total and LDL cholesterol. In addition, increasing MUFA intake rather than replacing saturated FAs by MUFAs also led to a decrease in total and LDL cholesterol [12]. Moreover, Alvaro et al. showed in Caco-2 cells that FAs were able to Available online at www.sciencedirect.com ScienceDirect Journal of Nutritional Biochemistry 24 (2013) 1751 – 1757 Abbreviations: ABCA1, ATP binding cassette A1; SR-BI, scavenger receptor class B type I; CD36, cluster determinant 36; DMEM, Dulbecco's modified Eagle's medium; NPC1L1, Niemann-pick C1-like 1; FBS, fetal bovine serum; FA, fatty acid; MUFA, monounsaturated FA; PUFA, polyunsaturated FA; PA, palmitic acid; OA, oleic acid; LA, linoleic acid; ALA, α-linolenic acid; ARA, arachidonic acid; EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid; FED, fish oil enriched in DHA; PBS, phosphate-buffered saline. ☆ Funding: AG was funded by a CIFRE grant from the ANRT (French National Association for Research and Technology) in partnership with Lesieur Company. This work was supported by both the CIFRE grant and the pOLIVd3 ANR (French National Research Agency) program ANR-10-ALIA-0008. ☆☆ Conflict of interest: Authors have no conflict of interest to declare. ⁎ Corresponding author. UMR 1062 INSERM/1260 INRA/Aix-Marseille Université Faculté de Médecine la Timone, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 5, France. Tel.: +33 4 91 29 41 02; fax: +33 4 91 78 21 01. E-mail address: Emmanuelle.Reboul@univ-amu.fr (E. Reboul). 0955-2863/$ - see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jnutbio.2013.03.004