[The relationship between tissue tumor necrosis factor-alpha(TNF-alpha) mRNA expression and gut-derived endotoxemia in rats after thermal injury]

To investigate the dynamic changes in tumor necrosis factor-alpha(TNF-alpha) mRNA expression and the relationship between TNF-alpha mRNA and gut-derived endotoxemia in rats after thermal injury.

56 male Wistar rats were subjected to a 35% total body surface area full-thickness thermal injury and randomly divided into 3 groups: normal controls, 35% III* injury group, and polymyxin B treatment group. Plasma endotoxin was measured by limulus amebocyte lysate test, and tissue TNF-alpha mRNA expression was determined by reverse transcription polymerase chain reaction (RT-PCR).

It was found that a significant elevation of endotoxin concentration in both portal and systemic circulation was observed at 2 hours after thermal injury, peaking at 8 hours (P < 0.05-0.01) and lowering at 24 hours. Meanwhile, TNF-alpha mRNA expression significantly increased in liver, lung, intestine, and kidney at 2 hours, peaking at 8 hours, and a high level was maintained till 24 hours. However, treatment with a low-dose polymyxin B could lower both portal and systemic endotoxin levels, and markedly inhibit TNF-alpha mRNA expression in various organs. In addition, a positive correlation between portal endotoxin concentration and pulmonary, intestinal and renal TNF-alpha mRNA expression was noted (r = 0.365-0.484, all P < 0.05).

This study suggests that major burns can lead to a marked elevation of tissue TNF-alpha mRNA expression in vital organs, which may be associated with gut-derived endotoxemia caused by acute thermal injury.