Glutamine deprivation facilitates tumour necrosis factor induced bacterial translocation in Caco-2 cells by depletion of enterocyte fuel substrate
Background and aims: Factors that induce luminal bacteria to cross the intestinal epithelium following injury remain poorly defined. The aim of this study was to investigate the interaction between glutamine metabolism, energy supply, and inflammatory mediators in determining the translocation of no...
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Published in | Gut Vol. 52; no. 2; pp. 224 - 230 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
London
BMJ Publishing Group Ltd and British Society of Gastroenterology
01.02.2003
BMJ BMJ Publishing Group LTD Copyright 2003 by Gut |
Subjects | |
Online Access | Get full text |
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Summary: | Background and aims: Factors that induce luminal bacteria to cross the intestinal epithelium following injury remain poorly defined. The aim of this study was to investigate the interaction between glutamine metabolism, energy supply, and inflammatory mediators in determining the translocation of non-pathogenic bacteria across cultured enterocytes. Methods: The effect of tumour necrosis factor α (TNF-α) on translocation of Escherichia coli C25 across Caco-2 epithelial monolayers was studied in the presence of products and inhibitors of glutamine metabolism. Simultaneous measurements of transepithelial electrical resistance (TEER) and flux of lucifer yellow were used to assess effects on the paracellular pathway. Lactate dehydrogenase release was used to monitor enterocyte integrity. Imaging of monolayers in these experimental conditions was undertaken with transmission electron microscopy. Results: Exposure to basolateral TNF-α (20 ng/ml) for six hours induced translocation of E coli across Caco-2 but only if accompanied by simultaneous glutamine depletion (p<0.01). Translocation was inhibited by addition of glutamine for two hours (p<0.01) but not by an isonitrogenous mixture of non-glutamine containing amino acids. Inhibition of glutamine conversion to α-ketoglutarate, but not blockade of glutathione or polyamine synthesis, also induced translocation in the presence of TNF-α. Manipulations that induced bacterial translocation were associated with a marked reduction in enterocyte ATP levels. No effect of these treatments on paracellular permeability or lactate dehydrogenase release was observed. Conditions in which translocation occurred were associated with the presence of bacteria within enterocyte vacuoles but not the paracellular space. Conclusions: In inflammatory conditions, the availability of glutamine as an enterocyte fuel substrate is essential for the preservation of a functional barrier to microorganisms. In conditions of acute glutamine depletion, cytokine mediated bacterial translocation appears to be primarily a transcellular process. |
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Bibliography: | Correspondence to:
Dr G L Carlson, Clinical Sciences Building, Hope Hospital, Eccles Old Rd, Salford M6 8HD UK;
gcarlson@fs1.ho.man.ac.uk href:gutjnl-52-224.pdf PMID:12524404 local:0520224 istex:1037EC355776AE2BEDCFA1EDF633CF915475D1EC ark:/67375/NVC-R3SWHXT8-K ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Correspondence to: Dr G L Carlson, Clinical Sciences Building, Hope Hospital, Eccles Old Rd, Salford M6 8HD UK; gcarlson@fs1.ho.man.ac.uk |
ISSN: | 0017-5749 1468-3288 1458-3288 |
DOI: | 10.1136/gut.52.2.224 |