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Gastroenterology. 2001 May;120(6):1393-403.

Inhibition of Na+,K+-ATPase by interferon gamma down-regulates intestinal epithelial transport and barrier function.

Author information

1
Martin Boyer Laboratories of the Inflammatory Bowel Disease Research Center, Department of Medicine, University of Chicago, Chicago, Illinois 60637, USA.

Abstract

BACKGROUND & AIMS:

To determine how interferon (IFN)-gamma inhibits epithelial barrier and ion transport functions, intestinal T84 cells were studied.

METHODS:

Acute and chronic effects of IFN-gamma on T84 barrier function, Na+,K+-adenosine triphosphatase (ATPase) activity, and certain ion transport and tight junctional proteins were determined. To assess the role of Na+,K+-ATPase and intracellular Na+, similar studies with the Na+,K+-ATPase inhibitor ouabain and Na+ ionophore monensin were performed. To determine the role of nitric oxide (NO), the NO donor SPER-NO was used.

RESULTS:

IFN-gamma acutely (<6 hour) decreased cellular Na+,K+-ATPase activity, followed later (>24 hours) by decreases in expression of Na/K/2Cl, the alpha subunit of Na+,K+-ATPase, occludin, and ZO-1. In contrast, cystic fibrosis transmembrane conductance regulator or the Na+ pump beta subunit were unchanged. Ouabain and monensin caused nearly identical changes to IFN-gamma. Incubation in low Na+ media significantly blunted the chronic effects of IFN-gamma. Hypotonic-induced cell swelling, in contrast, had effects similar to IFN-gamma but did not alter the expression of the Na+ pump alpha subunit. The NO donor SPER-NO rapidly inhibited Na+,K+-ATPase and also down-regulated transport and barrier proteins.

CONCLUSIONS:

IFN-gamma inhibition of Na+,K+-ATPase activity acutely causes increases in intracellular Na(i) concentration and cell volume, which are distinct signaling events that ultimately result in a leaky and dysfunctional epithelium associated with chronic inflammation.

PMID:
11313309
DOI:
10.1053/gast.2001.24045
[Indexed for MEDLINE]

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