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Neutrophil depletion attenuates human intestinal reperfusion injury
A C Sisley1, T Desai, J M Harig
1Department of Surgery, University of Chicago, Illinois 60637.
Abstract:
Intestinal ischemia/reperfusion injury (I/R) results from reactive oxygen metabolites generated by the xanthine oxidase system and activated neutrophils (PMN). In animal models, removing PMN from initial reperfusate has consistently decreased tissue injury. This experiment was designed to test this potential clinical treatment in human bowel subjected to I/R. The extent of reperfusion injury was assessed by measuring the activity of mucosal alkaline phosphatase (A phi), which is a specific marker of reperfusion injury. Human small intestine (n = 13) obtained at the time of organ harvest for transplantation was perfused for 60 min on an ex vivo perfusion circuit. Reperfusate consisted of autologous blood passed through a leukocyte filter (n = 6) or unfiltered blood (n = 7). Control intestine was sampled at harvest, after transport to the lab on ice (cold ischemia), and after 60 min warm ischemia. Mucosa was homogenized and assayed for A phi activity by cleavage of p-nitrophenyl phosphate. A phi activity (nmole/mg/min) was not decreased after either cold (774 +/- 37) or warm (753 +/- 40) ischemia compared to freshly harvested bowel (770 +/- 51). Both reperfused segments showed a significant decrease in A phi activity compared to controls (P < 0.05); however, reperfusion with leukocyte-filtered blood attenuated the decrease in enzyme activity compared to unfiltered blood (327 +/- 30 vs 506 +/- 25, P < 0.05), constituting an apparent reduction in injury of 35%. The observation that the severity of reperfusion injury was decreased by removal of PMN from the reperfusate demonstrates the efficacy of this strategy in human intestine for the first time.
Insights
Removing white blood cells from blood used to reperfuse human intestines significantly reduced tissue injury. This study demonstrates a promising clinical strategy for mitigating intestinal ischemia/reperfusion injury.
Area of Science:
- Gastroenterology
- Surgical Research
- Transplantation Medicine
Background:
- Intestinal ischemia/reperfusion (I/R) injury is a significant clinical challenge.
- Reactive oxygen metabolites and activated neutrophils (PMN) are key contributors to I/R injury.
- Animal models suggest PMN removal reduces tissue damage, but clinical data in humans is lacking.
Purpose of the Study:
- To evaluate the efficacy of removing leukocytes (white blood cells) from reperfusate in reducing human intestinal I/R injury.
- To assess the impact of leukocyte filtration on mucosal alkaline phosphatase (A phi) activity, a marker of reperfusion injury.
Main Methods:
- Human small intestine samples (n=13) from organ donors were used.
- Samples were subjected to ex vivo perfusion with either leukocyte-filtered (n=6) or unfiltered (n=7) autologous blood for 60 minutes.
- Mucosal A phi activity was measured as an indicator of reperfusion injury, comparing filtered, unfiltered, and control (ischemic) groups.
Main Results:
- Cold and warm ischemia did not significantly alter A phi activity compared to fresh tissue.
- Both reperfused groups showed decreased A phi activity compared to controls (P < 0.05).
- Leukocyte filtration significantly attenuated the decrease in A phi activity (327 vs 506, P < 0.05), indicating a 35% reduction in injury.
Conclusions:
- Removal of PMN from reperfusate significantly reduces reperfusion injury in human intestine.
- Leukocyte filtration represents a potential clinical strategy to mitigate intestinal I/R injury.
- This study provides the first evidence of PMN removal efficacy in human intestinal I/R.