[Effects of glutamine on the cytokine expression of peripheral blood mononuclear cells]

To investigate the effects of glutamine (Gln) on the cytokine expression of the peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide (LPS).

PBMCs were extracted from healthy volunteer by density gradient centrifugation. Suspension of PBMCs was pretreated with Gln of the concentrations of 1 mmol/L, 8 mmol/L, 10 mmol/L, and 15 mmol/L for 0.5 h and 2 h respectively. Suspension of PBMCs without Gln pretreatment but stimulated by LPS was used as positive control group, and suspension without LPS stimulation was used as negative control group. Then LPS was added ELISA was used to examine the levels of the mediators of inflammation, TNF-alpha, IL-1beta, IL-4, IL-6, IL-8, and IL-10, in the supernatant, and Gene Array Protocol was used to examine the mRNA expression of these cytokines.

After LPS stimulation, the expression levels of all the cytokines were obviously enhanced. The expression levels of the proinflammatory mediator, except for IL-6, of the Gln 8 mmoL/L 0.5 h group were significantly lower than those of the positive control group; and the expression levels of all the cytokines of the Gln 15 mmol/L 0.5 h group were significantly lower than those of the positive control group, however, all still significantly higher than those of the negative control group (P <0.01 or P <0.05). The expression levels of the proinflammatory mediator except for IL-8 of the Gln 1 mmol/L 0.5 h group did not significantly changed in comparison with the positive control group; and the level of IL-8 was significantly decreased (P <0.01). The expression levels of all the cytokines of the high concentrations Gln groups were all significantly lower than those of the positive control group. The levels of TNF-alpha, IL-6, and IL-8 of the high concentration Gln 2 h groups were all significantly higher then those of the concentration Gln 0.5 h groups (all P <0.01), however, there was not significant difference in the level of IL-1beta between the high concentration 0.5 h and 2 h Gln groups. The level of the anti-inflammatory mediator IL-10 of the high concentration Gln 0.5 h and 2 h groups, especially that of the latter group, were significantly lower than that of the positive control group (both P <0.01), however, the IL-10 level of the high concentration Gln 0.5 h group was still significantly higher than that of the negative control group (P < 0.05). Gene chip analysis confirmed the above results.

Glutamine dose- and time-dependently downregulates the expression of the mediators of inflammation, and lessen the excessive expression of those cytokines in cells stimulated by LPS.