title: Fluorescently labeled methyl-beta-cyclodextrin enters intestinal epithelial Caco-2 cells by fluid-phase endocytosis.
abstract: Cyclodextrins are widely used excipients for increasing the bioavailability of poorly water-soluble drugs. Their effect on drug absorption in the gastrointestinal tract is explained by their solubility- and permeability-enhancement. The aims of this study were to investigate penetration properties of fluorescently labeled randomly methylated-beta-cyclodextrin (FITC-RAMEB) on Caco-2 cell layer and examine the cellular entry of cyclodextrins on intestinal cells. The permeability of FITC-RAMEB through Caco-2 monolayers was very limited. Using this compound in 0.05 mM concentration the permeability coefficient was 3.35±1.29×10(-8) cm/s and its permeability did not change in the presence of 5 mM randomly methylated-beta-cyclodextrin. Despite of the low permeability, cellular accumulation of FITC-RAMEB in cytoplasmic vesicles was significant and showed strong time and concentration dependence, similar to the characteristics of the macropinocytosis marker Lucifer Yellow. The internalization process was fully inhibited at 0°C and it was drastically reduced at 37°C applying rottlerin, an inhibitor of macropinocytosis. Notably, FITC-RAMEB colocalized with the early endosome organizer Rab5a. These results have revealed that FITC-RAMEB is able to enter intestinal epithelial cells by fluid-phase endocytosis from the apical side. This mechanism can be an additional process which helps to overcome the intestinal barrier and contributes to the bioavailability enhancement of cyclodextrins.
authors.affiliation: Department of Pharmaceutical Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Fenyvesi
authors.affiliation: Department of Pharmaceutical Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Réti-Nagy
authors.affiliation: Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Bacsó
authors.affiliation: Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary.
authors.forename: Zsuzsanna
authors.initials: Z
authors.lastname: Gutay-Tóth
authors.affiliation: Cyclolab Cyclodextrin R&D Laboratory Ltd., Budapest, Hungary.
authors.forename: Milo
authors.initials: M
authors.lastname: Malanga
authors.affiliation: Cyclolab Cyclodextrin R&D Laboratory Ltd., Budapest, Hungary.
authors.forename: Éva
authors.initials: É
authors.lastname: Fenyvesi
authors.affiliation: Cyclolab Cyclodextrin R&D Laboratory Ltd., Budapest, Hungary.
authors.forename: Lajos
authors.initials: L
authors.lastname: Szente
authors.affiliation: Department of Pharmaceutical Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Váradi
authors.affiliation: Department of Pharmaceutical Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Ujhelyi
authors.affiliation: Department of Pharmaceutical Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Pálma
authors.initials: P
authors.lastname: Fehér
authors.affiliation: Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Szabó
authors.affiliation: Department of Pharmaceutical Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Miklós
authors.initials: M
authors.lastname: Vecsernyés
authors.affiliation: Department of Pharmaceutical Technology, University of Debrecen, Debrecen, Hungary.
authors.forename: Ildikó
authors.initials: I
authors.lastname: Bácskay
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism; D018938:Caco-2 Cells; D002454:Cell Differentiation / Q000187:drug effects; D004705:Endocytosis / Q000187:drug effects; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects; D005456:Fluorescent Dyes / Q000378:metabolism*; D006801:Humans; D007422:Intestines / Q000166:cytology*; D010539:Permeability / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D047392:beta-Cyclodextrins / Q000378:metabolism*; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D000098:Acetophenones; D001578:Benzopyrans; D015415:Biomarkers; D005456:Fluorescent Dyes; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C085746:rottlerin; D020696:rab5 GTP-Binding Proteins