Influence of glutamine on cytokine production by human gut in vitro

Background: glutamine modulates cytokine production by immune cells in vitr o and protects the gut from experimental enterocolitis, but data on the eff ect of glutamine on cytokine production in human gut are lacking. Aim: to a ssess the effect of glutamine pre-treatment in vivo and in vitro on cytokin e production by intestinal mucosa, Methods: nine fasted volunteers received either enteral glutamine or saline over 6 h in a cross-over design. Duoden al biopsies were cultured for 24 h with or without glutamine. Cytokine cont ent of culture media was analysed by ELISA, and the expression of cytokine mRNA in biopsies was assessed by semi-quantitative RT-PCR. Results: glutami ne given in vivo and in vitro significantly decreased IL-6 [1.4 (0.8-8.5) v s 8.9 (1.0-43.9)] and IL-8 production [5.8 (0-51.4) vs 53.0 (2.5-114.6), pg /mg wet tissue], median (range), both P less than or equal to0.01, in compa rison to no glutamine experiments. Glutamine did not influence IL-4 product ion. IL-1 beta, IL-10 and TNF-alpha were not detectable in culture media. T he expression of any cytokine mRNA was not influenced by glutamine, Conclus ions: glutamine reduces pro-inflammatory cytokine production by human intes tinal mucosa, probably by a post-transcriptional pathway. Glutamine could b e useful to modulate inflammatory conditions with imbalanced cytokine produ ction. (C) 2001 Academic Press.