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Role of activated macrophages in augmentation of endotoxin hepatotoxicity
Y Shibayama1, S Asaka, K Nakata
1Department of Pathology, Osaka Medical College, Japan.
Abstract:
In this study, to clarify the role of activated macrophages in the augmentation of endotoxin hepatoxicity, rats were pretreated with zymosan, an activator of macrophages, before the induction of endotoxin hepatotoxicity, and some were given pentoxifylline, an inhibitor of tumour necrosis factor production. The intravenous injection of zymosan induced many granulomas composed of macrophages in the lungs and the liver, while the intraperitoneal injection caused granulomas in the greater omentum. Endotoxin hepatotoxicity. as shown by focal and random hepatocellular coagulative necrosis and elevation of serum transaminase activities, was more intense in the rats pretreated with zymosan than in those which were not injected with zymosan. This augmented endotoxin hepatotoxicity was significantly inhibited by pentoxifylline treatment. These findings indicate that endotoxin hepatotoxicity may be augmented in the presence of activated macrophages which produce chemical mediators, particularly tumour necrosis factor.
Insights
Activated macrophages exacerbate endotoxin-induced liver injury in rats. Pentoxifylline, a tumor necrosis factor inhibitor, significantly reduced this enhanced hepatotoxicity, suggesting a key role for macrophages in liver damage.
Area of Science:
- Immunology
- Hepatology
- Toxicology
Background:
- Activated macrophages play a role in inflammatory responses.
- Endotoxin exposure can lead to liver injury (hepatotoxicity).
- Tumor necrosis factor (TNF) is a key inflammatory mediator.
Purpose of the Study:
- To investigate the role of activated macrophages in augmenting endotoxin-induced hepatotoxicity.
- To determine the effect of pentoxifylline, a TNF inhibitor, on this process.
Main Methods:
- Rats were pretreated with zymosan to activate macrophages.
- Endotoxin hepatotoxicity was induced.
- Some rats received pentoxifylline treatment.
- Liver damage and serum transaminase levels were assessed.
Main Results:
- Zymosan pretreatment led to granuloma formation in the liver and lungs.
- Endotoxin hepatotoxicity was significantly more severe in zymosan-pretreated rats.
- Pentoxifylline treatment significantly inhibited the augmented hepatotoxicity.
Conclusions:
- Activated macrophages augment endotoxin-induced liver injury.
- Tumor necrosis factor (TNF) produced by activated macrophages is a key mediator in this process.
- Targeting macrophage activation or TNF may offer therapeutic strategies for endotoxin-induced liver damage.