Vitamin D intestinal absorption is not a simple passive diffusion: evidences for involvement of cholesterol transporters.

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.

NPC1L1 and SR-BI are involved in intestinal cholesterol absorption from small-size lipid donors.

In the human intestinal content after a meal, cholesterol is dispersed in a complex mixture of emulsified droplets, vesicles, mixed micelles and precipitated material. The aim of this study was to determine the contribution of the main intestinal cholesterol transporters (NPC1L1, SR-BI) to the absorption processes, using different cholesterol-solubilizing donors. Cholesterol donors prepared with different taurocholate concentrations were added to an apical medium of differentiated TC7/Caco-2 cells.

Digestible and indigestible carbohydrates: interactions with postprandial lipid metabolism.

The balance between fats and carbohydrates in the human diet is still a matter of very active debate. Indeed, the processing of ordinary mixed meals involves complex processes within the lumen of the upper digestive tract for digestion, in the small intestine mucosa for absorption and resecretion, and in peripheral tissues and in the circulation for final handling. The purpose of this review is to focus on available knowledge on the interactions of digestible or indigestible carbohydrates with lipid and lipoprotein metabolism in the postprandial state.

Lutein transport by Caco-2 TC-7 cells occurs partly by a facilitated process involving the scavenger receptor class B type I (SR-BI).

The carotenoid lutein is thought to play a role in the human eye and to protect against age-related macular degeneration. Lutein transport in the human intestine has not been characterized. We examined lutein transport processes using Caco-2 TC-7 monolayers as a model for human intestinal epithelium.

Glucose and galactose regulate intestinal absorption of cholesterol.

A dose-dependent increase in cholesterol absorption was induced by glucose addition (0-75 mM) to the apical medium of TC7 cells, a well-characterized clone of Caco-2. The uptake into the cells and the secretion rate to the basolateral space were both enhanced by glucose and galactose. This up-regulation was suppressed by SGLT1 inhibition but not by GLUT2 inhibition.

Biliary anionic peptide fraction and apoA-I regulate intestinal cholesterol uptake.

Evidence is now in favor of protein-facilitated mechanisms for the intestinal cholesterol absorption. Here we report that the unesterified cholesterol uptake by rat jejunal brush border membrane vesicles (BBMVs) is efficient, saturable, and protein-mediated. The human apolipoproteins biliary anionic peptide factor (APF) and A-I (apoA-I) up-regulate micellar cholesterol uptake in a dose-dependent manner, but for all tested concentrations (0.

Homocysteine induces synthesis of a serine elastase in arterial smooth muscle cells from multi-organ donors.

Objectives: In heart transplant recipients with diffuse coronary arteriopathy, we have previously demonstrated the prevalence of elevated homocysteinemia, also known as an independent risk factor for myocardial infarction and stroke. In hyperhomocysteinemic mini-pigs we also observed early detectable pathologic changes in the elastic laminae. We hypothesized that homocysteine causes premature breakdown in the arterial elastic fibers by activation of the elastolytic activities.

Alterations of methionine fluxes and incorporation in intestines of miniature pigs fed a diet high in caseinate are restricted by angiotensin-converting enzyme inhibitor.

Previous results from our laboratory showed that a methionine-rich caseinate-based (metcas) diet induces hyperhomocysteinemia in miniature pigs. In the present study, the contribution of the ileal and jejunal methionine absorption to the dietary induced hyperhomocysteinemia was evaluated by measuring the mucosal to serosal fluxes and the enterocyte incorporation in intact intestinal epithelia mounted in Ussing chambers. For 4 mo, 20 miniature pigs were daily fed control or metcas diets, and an oral combination of an angiotensin-converting enzyme inhibitor (25 mg captopril, Cp) and diuretic (12.