Regulation of nitric oxide production in cultured human T84 intestinal epithelial cells by nuclear factor-kappa B-dependent induction of inducible nitric oxide synthase after exposure to bacterial endotoxin.
BACKGROUND
Intestinal epithelium is consistently in contact with lipopolysaccharide (LPS) produced by intraluminal microbes. LPS induces nitric oxide production in many rodent cells, but in human cells it is very differently regulated.


OBJECTIVE
To test the hypothesis that exposure to LPS up-regulates nitric oxide synthesis in human intestinal epithelium.


RESULTS
LPS induced nitric oxide synthesis in T84 cells in a time- and dose-dependent manner whereas detectable amounts of peroxynitrite were not produced. A novel selective inducible nitric oxide synthase (iNOS) inhibitor 1400 W potently inhibited LPS-induced nitric oxide synthesis in T84 cells while dexamethasone was relatively ineffective. Nitric oxide production was sensitive to cycloheximide, indicating that it was dependent on de novo protein synthesis. Nuclear factor-kappa B (NF-kappa B) inhibitor pyrrolidinedithiocarbamate abolished iNOS and nitric oxide production. Nitric oxide synthesis was also suppressed by genistein (tyrosine kinase inhibitor) and PD 98059 (p44/42 MAP kinase inhibitor) but enhanced by SB 203580 (p38 MAP kinase inhibitor).


CONCLUSIONS
Intestinal epithelial cells express iNOS and produce nitric oxide in a nuclear factor-kappa B-dependent manner when exposed to LPS. The process is regulated by tyrosine kinases, and p44/42 and p38 MAP kinases. Because nitric oxide acts as an antimicrobial agent and immune modulator, these findings are implicated in the regulation of gut mucosal immunity.
Lähde
M
M
The Immunopharmacological Research Group, Medical School, University of Tampere, and the Department of Clinical Chemistry, Tampere University Hospital, Finland.
Korhonen
R
R
Moilanen
E
E
D000578:Amidines / Q000494:pharmacology; D001596:Benzylamines / Q000494:pharmacology; D002478:Cells, Cultured; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007413:Intestinal Mucosa / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016328:NF-kappa B / Q000096:biosynthesis*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II
D000578:Amidines; D001596:Benzylamines; D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; C104820:N-(3-(aminomethyl)benzyl)acetamidine; D016328:NF-kappa B; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II