Effects of glutamine added to enteral nutrition on Peyer's patch apoptosis in severely burned mice

Abstract

Background and aims: This study aimed to investigate the influence of enteral glutamine (GLN) supplementation on Peyer's patch apoptosis in severely burned mice.

Methods: Thirty-four mice were randomly assigned to a normal group (n=10), an EN group (n=12) and an EN supplemented with GLN (EN+GLN) group (n=12) and the mice in the EN and EN+GLN groups received a full-thickness scald burn over 20% total body surface area (TBSA) on the back. The burned mice then were fed orally with a common EN or an isonitrogenous and isocaloric EN supplemented with GLN for 7 days. On day 7 after injury, all surviving mice were euthanised and the entire intestine was collected. The percentage of apoptotic cells and cell percentage of phenotype in Peyer's patches were determined by flow cytometry (FCM). The FasL expression in Peyer's patches was analysed by reverse transcription polymer chain reaction (RT-PCR) and FCM. Both TNF-alpha levels and caspase-3 activity in Peyer's patches were also assessed.

Results: The results revealed that the percentage of lymphocyte subsets in Peyer's patches after burn injury significantly altered: the percentage of CD4 and CD19 cells declined and the percentage of CD8 cells correspondingly increased, when compared with the normal control mice (p<0.05). On the other hand, the total apoptotic ratio and all lymphocytes subset apoptosis in Peyer's patches were markedly increased (p<0.05), which were consistent with up-regulation in the FasL expression at the levels of both mRNA and protein, TNF-alpha levels and caspase-3 activity in Peyer's patches. Enteral GLN supplementation partially reversed these changes: the total apoptotic ratio and all lymphocytes subpopulation apoptosis in Peyer's patches were markedly decreased when compared with the EN group (p<0.05). The percentage of lymphocyte subsets within Peyer's patches also restored the condition prior to injury. However, no significant differences in the FasL expression, including mRNA and protein, were observed between the EN and EN+GLN groups. Although, both TNF-alpha levels and caspase-3 activity in Peyer's patches were lower in the EN+GLN group than in the EN group (p<0.05).

Conclusions: This study suggests that enteral GLN supplementation is superior to a common enteral nutrition with respect to attenuating apoptosis in Peyer's patches, which might be more effective in decreasing TNF-alpha levels and down-regulating caspase-3 activity in Peyer's patches.