Glutamine decreases interleukin-8 and interleukin-6 but not nitric oxide and prostaglandins e(2) production by human gut in-vitro.
BACKGROUND
Glutamine modulates cytokine production in various tissues but its effects on the production of other inflammatory mediators such as eicosanoids and nitric oxide have not been investigated in human gut.


OBJECTIVE
To evaluate the influence of glutamine on interleukin (IL)-8, IL-6, nitric oxide and prostaglandin E(2) production by human gut.


METHODS
Ten fasted volunteers received either enteral glutamine or isonitrogenous amino acids over 6 h in a cross-over design. Series of duodenal biopsies were frozen or cultured for 24 h with 0.5 or 5 mM of glutamine or amino acids. IL-6, IL-8 and PGE(2) were measured in culture media by ELISA and nitrites by Griess assay. mRNA levels for IL-6, IL-8, Cyclooxygenase-2 and NO synthase-2 were assessed in biopsies by RT-PCR. Results in percent, (median [range]) were compared by Wilcoxon test.


RESULTS
Glutamine decreased IL-8 and IL-6 in-vitro production: 63 [2-173] vs 100 [19-177] and 37 [5-489] vs 100 [33-431], both P<0.05. IL-8 mRNA level also decreased in biopsies cultured with 5 mM glutamine: 26 [13-142] vs 92 [34-215], P<0.05. Nitrites and PGE(2) concentrations were not significantly affected by glutamine.


CONCLUSIONS
Glutamine has a specific inhibitory effect on pro-inflammatory cytokine production in the gut and may contribution to the modulation of intestinal inflammation.
Coëffier
Moïse
M
Appareil Digestif Environnement et Nutrition (ADEN EA 3234), Rouen, France.
Marion
Rachel
R
Leplingard
Antony
A
Lerebours
Eric
E
Ducrotté
Philippe
P
Déchelotte
Pierre
P
D000328:Adult; D001706:Biopsy; D002478:Cells, Cultured; D003470:Culture Media; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism*; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism*; D005973:Glutamine / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism*; D016209:Interleukin-8 / Q000235:genetics* / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics*; D007700:Kinetics; D008565:Membrane Proteins; D019001:Nitric Oxide Synthase / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects*
D003470:Culture Media; D015850:Interleukin-6; D016209:Interleukin-8; D007527:Isoenzymes; D008565:Membrane Proteins; D012333:RNA, Messenger; D005973:Glutamine; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone