Vitamin D intestinal absorption is not a simple passive diffusion: Evidences for involvement of cholesterol transporters
✍ Scribed by Emmanuelle Reboul; Aurélie Goncalves; Christine Comera; Romain Bott; Marion Nowicki; Jean-François Landrier; Dominique Jourdheuil-Rahmani; Claire Dufour; Xavier Collet; Patrick Borel
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 284 KB
- Volume
- 55
- Category
- Article
- ISSN
- 1613-4125
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Scope: It is assumed that vitamin D is absorbed by passive diffusion. However, since cholecalciferol (vitamin D~3~) and cholesterol display similar structures, we hypothesized that common absorption pathways may exist.
Methods and results: Cholecalciferol apical transport was first examined in human Caco‐2 and transfected Human embryonic kidney (HEK) cells. Cholecalciferol uptake was then valuated ex vivo and in vivo, using either wild‐type mice, mice overexpressing Scavenger Receptor class B type I (SR‐BI) at the intestinal level or mice treated or not with ezetimibe. Cholecalciferol uptake was concentration‐, temperature‐ and direction‐dependent, and was significantly impaired by a co‐incubation with cholesterol or tocopherol in Caco‐2 cells. Moreover Block Lipid Transport‐1 (SR‐BI inhibitor) and ezetimibe glucuronide (Niemann‐Pick C1 Like 1 inhibitor) significantly decreased cholecalciferol transport. Transfection of HEK cells with SR‐BI, Cluster Determinant 36 and Niemann‐Pick C1 Like 1 significantly enhanced vitamin D uptake, which was significantly decreased by the addition of Block Lipid Transport‐1, sulfo‐N‐succinimidyl oleate (Cluster Determinant 36 inhibitor) or ezetimibe glucuronide, respectively. Similar results were obtained in mouse intestinal explants. In vivo, cholecalciferol uptake in proximal intestinal fragments was 60% higher in mice overexpressing SR‐BI than in wild‐type mice (p<0.05), while ezetimibe effect remained non‐significant.
Conclusion: These data show for the first time that vitamin D intestinal absorption is not passive only but involves, at least partly, some cholesterol transporters.