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High levels of portal TNF-alpha during abdominal aortic surgery in man
A Cabiè1, J C Farkas, C Fitting
1Unité d'Immuno-Allergie, Institut Pasteur, Paris, France.
Abstract:
During shock or multiple organ dysfunction syndrome, translocation of bacteria and/or lipopolysaccharide (LPS) from the ischaemic gut might occur and could explain the excess of cytokine production detectable in plasma. To test this hypothesis, we studied a model of mild gut ischaemia due to bowel manipulation and aortic clamping in patients undergoing abdominal aortic surgery (n = 14). Per-operative levels of LPS and cytokines were measured before clamping and after reperfusion, and compared in systemic and portal blood. Systemic levels of LPS and cytokines were measured in a control group of patients undergoing internal carotid surgery (n = 7). Portal LPS was detectable (i.e., > 12 pg/ml) in 36% of the patients undergoing aortic surgery after bowel manipulation, and in 71% after clamp release. Similar levels of LPS were observed in portal and systemic blood after clamp release. Circulating tumour necrosis factor alpha (TNF-alpha) was observed in all patients undergoing aortic surgery. Levels of portal TNF-alpha were higher than those in systemic blood after bowel manipulation as well as after reperfusion (P = 0.02 and 0.007, respectively). LPS was never detected in control patients and TNF-alpha was detectable in only two out of seven patients. Mean levels of IL-6 were similar in the two groups, with a peak on the day following surgery, confirming that circulating IL-6 is associated with any surgical procedures. Our data indicate that bowel manipulation, aortic clamping and reperfusion lead to similar levels of portal and systemic circulating LPS.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Gut ischemia during abdominal aortic surgery increases bacterial product lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) in portal and systemic circulation, suggesting a link to organ dysfunction.
Area of Science:
- Gastroenterology
- Surgical Physiology
- Immunology
Background:
- Gut ischemia during shock or multiple organ dysfunction syndrome may cause bacterial translocation, leading to increased cytokine production.
- Lipopolysaccharide (LPS) translocation from the ischemic gut is a potential mechanism for elevated plasma cytokines.
Purpose of the Study:
- To investigate the hypothesis that gut ischemia during abdominal aortic surgery leads to bacterial and/or LPS translocation.
- To measure levels of LPS and cytokines in portal and systemic circulation during abdominal aortic surgery.
Main Methods:
- Studied 14 patients undergoing abdominal aortic surgery with mild gut ischemia induced by bowel manipulation and aortic clamping.
- Measured portal and systemic levels of LPS and cytokines (TNF-alpha, IL-6) before clamping and after reperfusion.
- Compared measurements with a control group (n=7) undergoing internal carotid surgery.
Main Results:
- Portal LPS was detected in 36% of patients after bowel manipulation and 71% after clamp release.
- Similar portal and systemic LPS levels were observed after clamp release in aortic surgery patients.
- Portal TNF-alpha levels were significantly higher than systemic levels post-manipulation and post-reperfusion (P=0.02, P=0.007).
Conclusions:
- Bowel manipulation, aortic clamping, and reperfusion in abdominal aortic surgery result in comparable portal and systemic LPS levels.
- Elevated portal TNF-alpha suggests local gut inflammatory response during aortic surgery.
- Findings support the role of gut-derived LPS and cytokines in systemic inflammatory responses following major abdominal surgery.