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Endotoxin and tumour necrosis factor do not cause mortality from caecal ligation and puncture
K M McMasters1, J C Peyton, D J Hadjiminas
1Department of Surgery, University of Louisville School of Medicine, Kentucky.
Abstract:
Macrophage tumour necrosis factor-alpha (TNF-alpha) production is thought to represent an important pathogenic mechanism by which Gram-negative sepsis is mediated. We compared the effects of caecal ligation and puncture (CLP) on endotoxin-sensitive (C3H/HeSnJ) and endotoxin-resistant (C3H/HeJ) mice. Mortality after CLP for C3H/HeSnJ mice compared with C3H/HeJ mice was not significantly different (32% and 55%, respectively). When survivors were injected with lipopolysaccharide intraperitoneally on the 7th day after CLP, the mortality rate was 82% for C3H/HeSnJ mice versus 0% for C3H/HeJ mice (P < 0.0001). Serum endotoxin levels at 24 h after CLP were only slightly elevated. Serum TNF levels and peritoneal macrophage TNF production were undetectable in C3H/HeJ mice and were only slightly elevated in C3H/HeSnJ mice by 24 h after CLP. Peritoneal macrophage mRNA levels for TNF-alpha, IL-1 beta, and I-A alpha displayed a similar pattern in the two strains of mice, with a 2- to 3-fold increase in TNF-alpha and IL-1 beta mRNA levels by 24 h and a sharp decrease in I-A alpha mRNA by 24 h. The cause of mortality in mice that undergo CLP cannot be attributed to overwhelming endotoxemia and/or TNF production.
Insights
Gram-negative sepsis mortality in mice is not solely due to endotoxemia or tumor necrosis factor-alpha (TNF-alpha) production. Further research is needed to understand sepsis pathogenesis beyond these factors.
Area of Science:
- Immunology
- Sepsis Pathogenesis
- Microbiology
Background:
- Macrophage tumor necrosis factor-alpha (TNF-alpha) production is a key mechanism in Gram-negative sepsis.
- Understanding the specific roles of endotoxins and TNF-alpha in sepsis mortality is crucial.
Purpose of the Study:
- To compare the effects of cecal ligation and puncture (CLP) in endotoxin-sensitive and endotoxin-resistant mice.
- To investigate the contribution of endotoxemia and TNF-alpha to mortality following CLP.
Main Methods:
- Cecal ligation and puncture (CLP) was performed on C3H/HeSnJ (endotoxin-sensitive) and C3H/HeJ (endotoxin-resistant) mice.
- Survivors were later challenged with lipopolysaccharide (LPS).
- Serum endotoxin and TNF levels, along with peritoneal macrophage mRNA expression (TNF-alpha, IL-1 beta, I-A alpha), were analyzed post-CLP.
Main Results:
- Mortality rates after CLP did not significantly differ between the two mouse strains.
- Endotoxin-resistant mice showed significantly higher survival rates when challenged with LPS post-CLP compared to endotoxin-sensitive mice.
- Serum endotoxin and TNF levels were only slightly elevated post-CLP, and macrophage mRNA levels for TNF-alpha and IL-1 beta showed modest increases, while I-A alpha decreased.
Conclusions:
- Mortality in mice undergoing CLP is not primarily caused by overwhelming endotoxemia or TNF-alpha production.
- The endotoxin resistance of C3H/HeJ mice confers significant protection against secondary LPS challenge after CLP.
- These findings suggest that other pathogenic mechanisms contribute to mortality in polymicrobial sepsis models.