Caracterisation des lipocortines presentes dans les cellules mononucleaires humaines. Etude du mecanisme et de la regulation de la secretion de la lipocortine I

SIGLEINIST T 76913 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Characterization of titanium dioxide nanoparticle intestinal absorption, in vivo and ex vivo, in the mouse

Titanium dioxide (TiO2) nanoparticles are ingested on a daily basis by millions of people, especially in western countries, being largely used as additive in manufactured foods or pharmaceutical drugs. Its oral administration was shown to exacerbate colitis, during UC or Crohn Diseases, by activating the NRLP3 inflammasome in gut and increasing its overall distribution in the blood or the spleen (Lomer MC Br J Nutr 2004;92:947, Ruiz PA, Gut. 2016 Feb 4. pii: gutjnl-2015-310297). Our study investigated the intestinal absorptive route of the alimentary TiO2 (E171) , after a unique gavage in mice, characterizing the major sites and kinetic of its absorption and distribution in the intestine and blood. The pathways of TiO2 absorption were also characterized ex vivo, in anesthetized mouse using specific inhibitors injected with the particles in ligatured loops of the jejunum. The TiO2 particles were detected using confocal microscopy and laser light reflection which uniquely permit to look at extended tissue area. The TiO2 particles from 100 nm to 1-2 micrometers showed a major absorption in the jejunum in both the villi and Peyer Patches and much lower uptake in ileon and colon. In villi the TiO2 absorption rose until 4 hours after feeding and returned to control levels at 8 h while Peyer patches contents remained low at 4h but are significantly increased at 8 h. TiO2 particles were also 4 time increased in the blood at 4 and 8 h, compared to controls, showing similar kinetics of accumulations as previously reported in human (Pele, L. C. et al. Part Fibre Toxicol, 2015 12, 26). In ex vivo experiments the absorption of TiO2 in ligatured loops of jejunum were found to be rapid, clearly visible after 15 or 30 minutes of incubation and is inhibited by 66 % in the presence of 100 mM of TAP (4,5,6-Triaminopyrimidine sulfate) a tight junction blocker suggesting a major absorption via a paracellular pathways across epithelial tight junctions. By contrast, the intestinal uptake of TiO2 was not modified in the presence of either 100 mM 5-(N-Ethyl-N-isopropyl) amiloride inhibiting pinocytosis, 30 µM pitstop 2 which blocks clathrin dependent endocytosis or17 µM methyl beta-cyclodextrin affecting raft-mediated endocytosis, showing little or no contribution of endocytosis in the absorptive process. We developed an easy method to rapidly follow the intestinal absorption of TiO2 by the intestine using confocal microscopy. The absorption occurred through out the intestine, being predominant in both villi and Peyer patches of the jejunum. Most TiO2 particles entered the intestine through a paracellular route, passed through it and were transferred to the blood in a few hours

Annexins from bovine adrenal cortex exhibit specific cytosol/membrane solvation

Cytosol/membrane localization of annexins I to VI was analyzed in tissue extracts from bovine adrenal cortex. Based on their solubility in either aqueous or detergents solutions, they were subfractionated in three groups named cytosolic (C), membrane-bound (MB) and membrane-inserted (MI). Less than 1% of the total annexins present in the tissue were recovered in the C fraction when as much as 76.5 and 22.5% were obtained respectively in the MB and the MI fractions. By immunoblotting after SDS-PAGE, it was shown that the various members of the annexin family were not equally recovered in the different fractions. A-V and A-VI were found present in the three fractions whereas the distribution of A-I, A-II, A-III and A-IV was distinct, suggesting different cellular functions

Characterization of cytosolic lipid droplets and their traffic in mouse intestine or Caco-2 cells

Characterization of cytosolic lipid droplets and their traffic in mouse intestine or Caco-2 cells. FASEB Scientific Research Conferenc

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

International audienc

Intestinal membrane transporters follow the trail of fat into cytosolic lipid droplets, during digestion

Intestinal membrane transporters follow the trail of fat into cytosolic lipid droplets, during digestion. Digestive Disease Week / 102nd Annual AGA meetin

Exposure to dietary lipid leads to rapid production of cytosolic lipid droplets near the brush border membrane of enterocytes

Exposure to dietary lipid leads to rapid production of cytosolic lipid droplets near the brush border membrane of enterocytes. 2. International Conference on Metabolic Syndrom