title: Tumor necrosis factor-alpha increases sodium and chloride conductance across the tight junction of CACO-2 BBE, a human intestinal epithelial cell line.
abstract: CACO-2 BBE was used to determine the response of a gastrointestinal epithelium to tumor necrosis factor-alpha (TNF). Incubation of CACO-2 BBE with TNF did not produce any effect on transepithelial resistance (TER) within the first 6 hr but resulted in a 40-50% reduction in TER and a 30% decrease in 1SC (short circuit current) relative to time-matched control at 24 hr. The decrease in TER was sustained up to 1 week following treatment with TNF and was not associated with a significant increase in the transepithelial flux of [14C]-D-mannitol or the penetration of ruthenium red into the lateral intercellular space. Dilution potential and transepithelial 22Na+ flux studies demonstrated that TNF-treatment of CACO-2 BBE cell sheets increased the paracellular permeability of the epithelium to Na+ and Cl-. The increased transepithelial permeability did not associate with an increase in the incidence of apoptosis. However, there was a TNF-dependent increase in [3H]-thymidine labeling that was not accompanied by a change in DNA content of the cell sheet. The increase in transepithelial permeability was concluded to be across the tight junction because: (i) 1 mM apical amiloride reduced the basolateral to apical flux of 22Na+, and (ii) dilution potential studies revealed a bidirectionally increased permeability to both Na+ and Cl-. These data suggest that the increase in transepithelial permeability across TNF-treated CACO-2 BBE cell sheets arises from an alteration in the charge selectivity of the paracellular conductive pathway that is not accompanied by a change in its size selectivity.
authors.affiliation: Lankenau Medical Research Center, Wynnewood, PA 19096, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Marano
authors.forename: S A
authors.initials: SA
authors.lastname: Lewis
authors.forename: L A
authors.initials: LA
authors.lastname: Garulacan
authors.forename: A P
authors.initials: AP
authors.lastname: Soler
authors.forename: J M
authors.initials: JM
authors.lastname: Mullin
mesh_terms: D018938:Caco-2 Cells; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002712:Chlorides / Q000502:physiology*; D004553:Electric Conductivity; D004594:Electrophysiology; D004847:Epithelial Cells / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa; D012964:Sodium / Q000502:physiology*; D019108:Tight Junctions / Q000187:drug effects* / Q000502:physiology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D002712:Chlorides; D014409:Tumor Necrosis Factor-alpha; D012964:Sodium