Tumor necrosis factor-alpha mediates hyperglycemia-augmented gut barrier dysfunction in endotoxemia.

Abstract

OBJECTIVE:

To examine whether hyperglycemia would augment gut barrier dysfunction and inflammatory responses in endotoxemic rats, and simultaneously to clarify the roles of tumor necrosis factor (TNF)-alpha in alterations of gut mucosal permeability associated with hyperglycemia.

DESIGN:

Prospective randomized animal study.

SETTING:

University research laboratory.

SUBJECTS:

: Male Wistar rats treated with lipopolysaccharide (LPS) injection.

INTERVENTIONS:

After LPS injection (4 mg/kg), rats were randomly allocated into group S (n = 6), group G (n = 7), or group GI (n = 8) with continuous infusion of different fluid solutions: normal saline, 40% glucose or 10% glucose mixed with insulin, respectively. Blood glucose, insulin, and proinflammatory cytokines, accompanied by gut mucosal permeability using an in situ loop preparation of gut with fluorescence isothiocyanate-conjugated dextran, were measured. Bacterial growth or alterations in mesenteric lymph nodes and cecal contents were also assessed. We further determined the roles of TNF-alpha using an inhibitor of TNF-alpha converting enzyme in gut barrier dysfunction under the same experimental settings.

MEASUREMENTS AND MAIN RESULTS:

Hyperglycemia over 400 mg/dL was achieved and kept in group G during the study period whereas normoglycemia was preserved in group S and GI, the latter of which showed the similar extent of hyperinsulinemia to group G. Plasma concentrations of fluorescence-labeled dextran and TNF-alpha in group G were significantly higher vs. group S and GI, and the number of bacteria found in mesenteric lymph nodes in group G was greater compared with group S. Intestinal environments including microflora and organic acids were not altered by blood glucose or insulin level. Inhibiting conversion of membrane-bound to soluble type of TNF-alpha restored gut mucosal permeability augmented by hyperglycemia.

CONCLUSIONS:

These findings indicate that hyperglycemia deteriorates LPS-elicited gut barrier dysfunction and bacterial translocation independently of plasma insulin level, and that TNF-alpha mediates such mucosal dysfunction of gut in endotoxemia.

• Authors: Satoshi Yajima, Hiroshi Morisaki, Ryohei Serita, Takeshi Suzuki, Nobuyuki Katori, Takashi Asahara, Koji Nomoto, Fujio Kobayashi, Akitoshi Ishizaka, Junzo Takeda
• Journal: Critical care medicine (Crit Care Med) Vol. 37 Issue 3 Pg. 1024-30 (Mar 2009) ISSN: 1530-0293 [Electronic] United States
• PMID: 19237913 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Tumor Necrosis Factor-alpha

Topics

• Animals
• Endotoxemia (blood, complications, immunology, metabolism, physiopathology)
• Hyperglycemia (blood, complications, immunology, metabolism, physiopathology)
• Intestinal Mucosa (metabolism)
• Intestines (microbiology)
• Male
• Permeability
• Rats
• Rats, Wistar
• Tumor Necrosis Factor-alpha (physiology)