Real-time monitoring of trans-epithelial electrical resistance in cultured intestinal epithelial cells: the barrier protection of water-soluble dietary fiber.
OBJECTIVES
In this study we aimed to verify a real-time trans-epithelial electrical resistance (TEER) monitoring system in a Caco-2 monolayer and to investigate the therapeutic effect of partially hydrolyzed guar gum (PHGG), a dietary fiber, against interferon (IFN)-γ-induced intestinal barrier dysfunction using this monitoring system.


METHODS
We measured TEER using a real-time monitoring system and evaluated epithelial paracellular permeability using fluorescein isothiocyanate-conjugated dextran (4 kDa; FD4) in Caco-2 monolayers treated with IFN-γ for 48 h. The expression and distribution of tight junction (TJ)-associated proteins, ZO-1 and occludin, were analyzed by Western blot and immunocytochemistry, respectively. In some experiments PHGG was added prior to IFN-γ treatment in order to investigate its protective effect on barrier function.


RESULTS
IFN-γ treatment significantly decreased TEER and increased FD4 flux across Caco-2 monolayers, indicating a great influence of IFN-γ on the intestinal epithelial paracellular permeability. In contrast, the pretreatment of PHGG significantly reduced the IFN-γ-induced increment of FD4 flux without affecting TEER. Neither IFN-γ nor PHGG treatment affected the expressions of TJ-associated proteins, while immunocytochemistry showed that IFN-γ-induced redistribution of occludin was clearly restored by PHGG.


CONCLUSIONS
Real-time TEER monitoring enabled us to evaluate the dynamic changes of intestinal epithelial barrier function. PHGG may have a protective effect against IFN-γ-induced barrier dysfunction by attenuating the paracellular hyperpermeability; thus, its promotion as a functional food is anticipated.
['Majima|Atsushi|A|', 'Handa|Osamu|O|', 'Naito|Yuji|Y|', 'Suyama|Yosuke|Y|', 'Onozawa|Yuriko|Y|', 'Higashimura|Yasuki|Y|', 'Mizushima|Katsura|K|', 'Morita|Mayuko|M|', 'Uehara|Yukiko|Y|', 'Horie|Hideki|H|', 'Iida|Takaya|T|', 'Fukui|Akifumu|A|', 'Dohi|Osamu|O|', 'Okayama|Tetsuya|T|', 'Yoshida|Naohisa|N|', 'Kamada|Kazuhiro|K|', 'Katada|Kazuhiro|K|', 'Uchiyama|Kazuhiko|K|', 'Ishikawa|Takeshi|T|', 'Takagi|Tomohisa|T|', 'Konishi|Hideyuki|H|', 'Yasukawa|Zenta|Z|', 'Tokunaga|Makoto|M|', 'Okubo|Tsutomu|T|', 'Itoh|Yoshito|Y|']
D018938:Caco-2 Cells D004043:Dietary Fiber D017097:Electric Impedance D004847:Epithelial Cells D005685:Galactans D006801:Humans D006861:Hydrogen Peroxide D007371:Interferon-gamma D007413:Intestinal Mucosa D008351:Mannans D010539:Permeability D053149:Plant Gums D012995:Solubility D062725:Tight Junction Proteins D019108:Tight Junctions
trans-epithelial electrical resistance partially hydrolyzed guar gum paracellular permeability occludin intestinal barrier function