The effect of glutamine infusion on the inflammatory response and HSP70 during human experimental endotoxaemia

Abstract

Introduction: Glutamine supplementation has beneficial effects on morbidity and mortality in critically ill patients, possibly in part through an attenuation of the proinflammatory cytokine response and a stimulation of heat shock protein (HSP)70. We infused either alanine-glutamine or saline during endotoxin challenge and measured plasma cytokines and HSP70 protein expression.

Methods: This crossover study, conducted in eight healthy young men, was double-blind, randomized and placebo-controlled. It was performed on 2 trial days, separated by a 4-week washout period. The volunteers received an infusion of alanine-glutamine at a rate of 0.025 g/(kg body weight x hour) or saline for 10 hours. After 2 hours, an intravenous bolus of Escherichia coli endotoxin (0.3 ng/kg) was administered. Blood samples were collected hourly for the following 8 hours. HSP70 protein content in isolated blood mononuclear cells (BMNCs) was measured by Western blotting.

Results: Plasma glutamine increased during alanine-glutamine infusion. Endotoxin reduced plasma glutamine during both trials, but plasma glutamine levels remained above baseline with alanine-glutamine supplementation. Endotoxin injection was associated with alterations in white blood cell and differential counts, tumour necrosis factor-alpha, IL-6, temperature and heart rate, but glutamine affected neither the endotoxin-induced change in these variables nor the expression of HSP70 in BMNCs.

Conclusions: Endotoxin reduced plasma glutamine independently of alanine-glutamine infusion, but supplementation allows plasma levels to be maintained above baseline. Glutamine alters neither endotoxin-induced systemic inflammation nor early expression of HSP70 in BMNCs.

Trial registration: ClinicalTrials.gov ID: NCT 00780520.

Trial registration: ClinicalTrials.gov NCT00780520.

Figure 1

Evolution of clinical and biochemical variables after endotoxin challenge and infusion with glutamine or placebo. Shown is the time course of clinical and biochemical variables after an intravenous bolus of endotoxin (vertical dotted line indicates time of endotoxin administration) and infusion with glutamine (squares) or placebo (triangles) in young healthy volunteers: (a) plasma glutamine, (b) IL-6, (c) tumour necrosis factor (TNF)-α, (d) cortisol, (e) rectal temperature and (f) heart rate. Values are expressed as means ± standard error of the mean. The result of a mixed model analysis is given below each graph. In panels e and f, hourly measurements are shown for clarity, although measurements performed every 15 minutes were included in the analysis. *P < 0.05, post hoc t-test from the start of the trial to the time of endotoxin administration; ^#P < 0.05, post hoc t-test of the difference from administration of endotoxin to time point during placebo infusion.

Figure 2

Evolution of HSP70 concentrations after endotoxin challenge and infusion with glutamine or placebo. Shown is the time course of heat shock protein (HSP)70 concentrations in blood mononuclear cells after endotoxin administration (vertical dotted line indicates time of injection) and infusion with glutamine (squares) or placebo (triangles). Values are expressed as mean ± standard error of the mean. The result of a mixed model analysis is given below the figure.

Figure 3

Evolution of leucocyte subpopulations after endotoxin challenge and infusion with glutamine or placebo. Shown is the time course of leucocyte subpopulations in plasma after endotoxin administration (vertical dotted line indicates time of injection) and infusion with glutamine (squares) or placebo (triangles): (a) monocytes, (b) lymphocytes and (c) neutrophils. Values are expressed as mean ± standard error of the mean. The result of a mixed model analysis is given below each graph. ^#P < 0.05, post hoc t-test of difference from administration of endotoxin to time point during placebo infusion.