Camille Dugardin1, Olivier Briand1, Véronique Touche1, Marleen Schonewille2, François Moreau3, Cédric Le May3, Albert K Groen2,4, Bart Staels5, Sophie Lestavel1. 1. Inserm, CHU Lille, Institut Pasteur de Lille, U1011 - EGID, Univ. Lille, 59000, Lille, France. 2. University Medical Center Groningen, Department of Pediatrics, University of Groningen, Groningen, The Netherlands. 3. INSERM, UMR 1087, CNRS UMR 6291, 44000, Nantes, France. 4. Academic Medical Center, Amsterdam, The Netherlands. 5. Inserm, CHU Lille, Institut Pasteur de Lille, U1011 - EGID, Univ. Lille, 59000, Lille, France. bart.staels@pasteur-lille.fr.
Abstract
AIMS: The dyslipidemia associated with type 2 diabetes is a major risk factor for the development of atherosclerosis. Trans-intestinal cholesterol excretion (TICE) has recently been shown to contribute, together with the classical hepatobiliary route, to fecal cholesterol excretion and cholesterol homeostasis. The aim of this study was to develop an in vitro cell model to investigate enterocyte-related processes of TICE. METHODS: Differentiated Caco-2/TC7 cells were grown on transwells and incubated basolaterally (blood side) with human plasma and apically (luminal side) with lipid micelles. Radioactive and fluorescent cholesterol tracers were used to investigate cholesterol uptake at the basolateral membrane, intracellular distribution and apical excretion. RESULTS: Our results show that cholesterol is taken up at the basolateral membrane, accumulates intracellularly as lipid droplets and undergoes a cholesterol acceptor-facilitated and progressive excretion through the apical membrane of enterocytes. The overall process is abolished at 4 °C, suggesting a biologically active phenomenon. Moreover, this trans-enterocytic retrograde cholesterol transport displays some TICE features like modulation by PCSK9 and an ABCB1 inhibitor. Finally, we highlight the involvement of microtubules in the transport of plasma cholesterol from basolateral to apical pole of enterocytes. CONCLUSIONS: The human Caco-2/TC7 cell line appears a good in vitro model to investigate the enterocytic molecular mechanisms of TICE, which may help to identify intestinal molecular targets to enhance reverse cholesterol transport and fight against dyslipidemia.
AIMS: The dyslipidemia associated with type 2 diabetes is a major risk factor for the development of atherosclerosis. Trans-intestinal cholesterol excretion (TICE) has recently been shown to contribute, together with the classical hepatobiliary route, to fecal cholesterol excretion and cholesterol homeostasis. The aim of this study was to develop an in vitro cell model to investigate enterocyte-related processes of TICE. METHODS: Differentiated Caco-2/TC7 cells were grown on transwells and incubated basolaterally (blood side) with human plasma and apically (luminal side) with lipid micelles. Radioactive and fluorescent cholesterol tracers were used to investigate cholesterol uptake at the basolateral membrane, intracellular distribution and apical excretion. RESULTS: Our results show that cholesterol is taken up at the basolateral membrane, accumulates intracellularly as lipid droplets and undergoes a cholesterol acceptor-facilitated and progressive excretion through the apical membrane of enterocytes. The overall process is abolished at 4 °C, suggesting a biologically active phenomenon. Moreover, this trans-enterocytic retrograde cholesterol transport displays some TICE features like modulation by PCSK9 and an ABCB1 inhibitor. Finally, we highlight the involvement of microtubules in the transport of plasma cholesterol from basolateral to apical pole of enterocytes. CONCLUSIONS: The human Caco-2/TC7 cell line appears a good in vitro model to investigate the enterocytic molecular mechanisms of TICE, which may help to identify intestinal molecular targets to enhance reverse cholesterol transport and fight against dyslipidemia.
Authors: Verena Hiebl; Daniel Schachner; Angela Ladurner; Elke H Heiss; Herbert Stangl; Verena M Dirsch Journal: Biol Proced Online Date: 2020-04-11 Impact factor: 3.244