title: Laurate permeabilizes the paracellular pathway for small molecules in the intestinal epithelial cell model HT-29/B6 via opening the tight junctions by reversible relocation of claudin-5. [Corrected].
abstract: OBJECTIVE
  To mechanistically analyze effects of the medium-chain fatty acid laurate on transepithelial permeability in confluent monolayers of the intestinal epithelial cell line HT-29/B6, in context with an application as an absorption enhancer improving transepithelial drug permeation.
  
  
  METHODS
  Transepithelial resistance and apparent permeability for paracellular flux markers was measured using Ussing-type chambers. Two-path impedance spectroscopy was employed to differentiate between transcellular and paracellular resistance, and confocal imaging and Western blotting was performed.
  
  
  RESULTS
  Laurate resulted in a substantial and reversible decrease in transepithelial resistance by 50% which was attributed to a decrease in paracellular resistance. Simultaneously, an increase in permeability for fluorescein (330 Da) was detected, while permeabilities for 4 kDa FITC-dextran and sulpho-NHS-SS-biotin (607 Da) remained unaltered. Confocal laser-scanning microscopy revealed a marked reduction of claudin-5, while other tight junction proteins including tricellulin, a protein preventing the paracellular passage of macromolecules, were not affected.
  
  
  CONCLUSIONS
  Laurate induces an increase in paracellular permeability for molecules up to a molecular mass of 330 Da by retrieval of claudin-5 from tight junctions without affecting tricellular contacts and the paracellular passage of macromolecules. We hereby provide, for the first time, a mechanistical explanation of laurate-induced permeability enhancement on molecular level.
authors.affiliation: Institute of Clinical Physiology, Charité, Campus Benjamin Franklin, 12200, Berlin, Germany.
authors.forename: Isabel
authors.initials: I
authors.lastname: Dittmann
authors.forename: Maren
authors.initials: M
authors.lastname: Amasheh
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Krug
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Markov
authors.forename: Michael
authors.initials: M
authors.lastname: Fromm
authors.forename: Salah
authors.initials: S
authors.lastname: Amasheh
mesh_terms: D001710:Biotin / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D002463:Cell Membrane Permeability / Q000187:drug effects; D062507:Claudin-5 / Q000378:metabolism*; D003911:Dextrans / Q000493:pharmacokinetics; D019793:Fluorescein / Q000493:pharmacokinetics; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D019073:HT29 Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000378:metabolism; D007848:Laurates / Q000494:pharmacology*; D010539:Permeability / Q000187:drug effects*; D013388:Succinimides / Q000493:pharmacokinetics; D019108:Tight Junctions / Q000187:drug effects* / Q000378:metabolism
chemical_list: D062507:Claudin-5; D003911:Dextrans; D007848:Laurates; D013388:Succinimides; C015219:fluorescein isothiocyanate dextran; C094773:sulfosuccinimidyl-2-(biotinamido)ethyl-1,3-dithiopropionate; D001710:Biotin; D016650:Fluorescein-5-isothiocyanate; D019793:Fluorescein