Cytokine-stimulated nitric oxide production and inducible NO-synthase mRNA level in human intestinal cells: lack of modulation by glutamine.
OBJECTIVE
Excess NO production has been reported during intestinal inflammation. Modulation of the inflammatory response with nutrients in critically ill patients has gained increasing interest. Glutamine has beneficial effects on gut mucosa but its effects on human intestinal NO production during an inflammatory response are not known.


METHODS
Caco-2/TC7 and HCT-8 cells were stimulated with a cytokine mixture (IL-1 beta, TNF alpha, IFN gamma) and duodenal biopsies from human healthy volunteers in organ culture were stimulated with IL-1 beta. All cultures were performed in the presence of 2-10 mmol/l glutamine. NO release in culture supernatant and iNOS mRNA level in cultured cells or biopsies were assessed by nitrate reduction and Griess assay and RT-PCR, respectively.


RESULTS
In Caco-2, HCT-8 cells and duodenal biopsies, cytokine stimulation increased iNOS mRNA level 1.2-fold (ns), 3.8-fold (P=0.02), 4.7-fold (P=0.03) and NO production 1.4-fold (ns), 9.1 (P=0.01) and 1.7-fold (P=0.01), respectively. Increasing glutamine concentration had no significant effect on NO production and iNOS mRNA in any type of culture, stimulated or not by cytokines. In various models of human intestinal cells, glutamine does not further increase NO production induced by pro-inflammatory cytokines.
Marion
R
R
Appareil Digestif Environnement Nutrition (ADEN EA 3234), Institut Fédératif de Recherches Multidisciplinaires sur les Peptides (I.F.R.23), Rouen, France.
Coëffier
M
M
Leplingard
A
A
Favennec
L
L
Ducrotté
P
P
Déchelotte
P
P
D000328:Adult; D018938:Caco-2 Cells; D018929:Cell Culture Techniques; D016207:Cytokines / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005973:Glutamine / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007422:Intestines / Q000166:cytology / Q000187:drug effects; D008954:Models, Biological; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018709:Statistics, Nonparametric
D016207:Cytokines; D012333:RNA, Messenger; D005973:Glutamine; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II