Down-regulation of Tissue Specific Tumor Necrosis Factor-alpha in the Liver and Lung after Burn Injury and Endotoxemia

Abstract

Burn injury and endotoxin lead to the development of a systemic inflammatory response. Because tumor necrosis factor-alpha (TNF-alpha) is a component of the proinflammatory response, we have determined the effect of burn injury and endotoxin in a murine model of thermal on tissue specific TNF-alpha levels in the liver and lung. Male mice were divided into four groups and injected with endotoxin (ETX) (2.5 mg/kg intraperitoneally) or saline (CNTL) or subjected to a 16% full-thickness scald burn (B), or ETX administration 72 hours after burn injury (B+ETX). Animals were killed at 0 to 24 hours after ETX or CNTL, 0 to 72 hours after B, and 72 to 96 hours after B+ETX (ETX administration 72 hours after B). TNF-alpha mRNA by Northern blot and protein analysis by enzyme-linked immunosorbent assay were determined and protein expressed as nanogram per gram of tissue. Statistical analysis was performed using analysis of variance with significance at p < 0.05. Burn injury did not result in detectable levels of liver or lung TNF protein or mRNA. Endotoxin administration resulted in a near six-fold rise in liver TNF protein compared with controls at 1, 2, and 6 hours after ETX (p < 0.05 to p < 0.001). Liver mRNA remained elevated from 20 minutes to 24 hours after ETX versus CNTL (p < 0.05). Endotoxin injection produced a persistent lung TNF protein elevation reaching significance at 1 and 2 hours (p < 0.001) and a rise in mRNA at 40 minutes to 6 hours (p < 0.05) versus CNTL. The liver showed a trend of reduced mRNA after B+ETX versus ETX (p = NS), whereas protein levels were reduced by 50 to 60% at 1 and 2 hours (p < 0.01). Lung mRNA values after B+ETX were only 40% compared with ETX at nearly all time points (p < 0.001) but were 15 times above CNTL values at 2 hours (p < 0.05). Based on these results, we conclude that burn injury did not cause an increase in liver or lung tissue specific TNF-alpha. However, the presence of a preexisting burn injury dramatically altered the response to endotoxin and the primary point of regulation appears to be at the posttranscriptional level.

Smoke/Burn Injury-Induced Respiratory Failure Elicits Apoptosis in Ovine Lungs and Cultured Lung Cells, Ameliorated With Arteriovenous CO 2 Removal

“…Hales et al 4 were unable to demonstrate a role for TNF-␣ in sheep after smoke and burn injury; our study extends their findings and takes place much later, after the application of supportive therapy. We are in agreement with Clancy et al, 40 who did not document elevated TNF-␣ levels when they examined whole-organ responses and speculate that elevated systemic levels of TNF-␣ likely represent a late manifestation of the inflammatory response. In agreement with others is the fact that we were unable to detect TNF-␣ in ovine sera, 41 although we did detect the result of its effect on cells grown in the serum.…”

“…5,36 Mechanical ventilation has been shown to predispose patients to the development of systemic inflammatory response that leads to local tissue injury, multiple organ dysfunction, and death. 18,19,36 -38 The result in these animals (LD 40 ) was an increased presence of apoptotic cells in the respiratory tissue as well as an almost total obliteration of normal architecture (Figs 4,5). The effects on lung cells in culture showed an increase in the number of apoptotic cells as documented by DNA fragmentation (Fig 8) and hoechst staining (Fig 4, top, A).…”

Contribution of gene expression to metabolic fluxes in hypermetabolic livers induced through burn injury and cecal ligation and puncture in rats

“…Prior studies have documented that CLP treatment can lead to a decrease in the activity of certain gluconeogenic enzymes, such as phosphoenolpyruvate carboxykinase (Deutschman et al, 1995). The priming burn may partially protect from the effect of CLP by inducing ''endotoxin resistance'' (Clancy et al, 1997). Thus, the lack of an increase in gluconeogenic fluxes in perfused livers from Burn-CLP and Sham-CLP animals is more likely due to the fact that lactate levels in the perfusate medium were not increased relative to the Sham-Sham perfusions.…”

Putative role of TNF-α, interleukin-8 and ICAM-1 as indicators of an early inflammatory reaction after burn: a morphological and immunohistochemical study of lung tissue of fire victims

“…Hales et al were not able to prove any influence of TNF-α in smoke-induced microvascular lung injury in sheep, but found an increase of TNF-α in lymph fluid of the lung after injection of endotoxin 25. Some other authors27 28 were also able to demonstrate an increase of TNF-α in burn disease in men, but this might have been due to bacterial superinfections 20 26…”

“…Thus, microscopically no reactive inflammatory cell infiltrates were found in our cases. Moreover, it is possible that not only the inhalation of heat and combustion gas, but additional factors like endotoxins20 25 26 may be necessary to increase TNF-α expression in the lung. Since ICAM-1 becomes activated via TNF-α, the absence of ICAM-1 expression in our cases is plausible, as it should become manifest only at a later stage of the inflammatory process.…”