Correlation of taurine transport with membrane lipid composition and peroxidation in DHA-enriched Caco-2 cells.

Diets supplemented with n-3 polyunsaturated fatty acids can promote lipid peroxidation and the propagation of oxygen radicals. These effects can be prevented by taurine, a functional ingredient with antioxidant properties. Here, we examined whether there is a correlation between transepithelial taurine transport, on the one hand, and membrane fatty acid composition and peroxidation in intestinal Caco-2 cells, on the other. Differentiated Caco-2 cells were maintained for 10 days, from the day of confluence, in control conditions or in a medium enriched with docosahexaenoic acid (DHA, 100 micromol/l), taurine (10 mmol/l) or DHA plus taurine. Incubation of the monolayers in a medium enriched with DHA increased the incorporation of this fatty acid into the brush-border membrane, at the expense of total n-6 fatty acids (C20:2n-6, C20:3n-6 and C22:4n-6). This was paralleled by increased membrane lipid peroxidation, which was partially limited by the addition of taurine. Transepithelial taurine transport was estimated from taurine uptake and efflux kinetic parameters at apical and basolateral domains. Cell incubation with DHA increased basolateral taurine uptake through an increase in V (max), whereas incubation with taurine downregulated basolateral uptake as occurred for apical taurine transporter. Moreover, addition of DHA reduced the apical downregulation effect exerted on taurine transport by taurine incubation. Our results suggest that the oxidative status of epithelial cells regulates taurine transport, thus satisfying antioxidant cellular requirements.