Mechanismus und Bedeutung des Organentnahme-und Reperfusionsschadens in der intestinalen Muskularis für die Dünndarmtransplantation

Abstract

Ischemia and reperfusion or gentle gut manipulation evoke an inflammatory response within the intestinal muscularis that is associated with a decrease in intestinal motility. We hypothesize that intestinal manipulation during organ harvesting initiates an inflammatory response within the intestinal muscularis which is amplified during reperfusion. Furthermore we believe that macrophages play a key role in initiating the inflammatory cascade. Methods: Orthotopic intestinal transplantation was performed in Lewis rats. To investigate the impact of organ harvesting on muscularis inflammation cold whole body perfusion was performed after versus prior to organ harvesting. Macrophage depletion was induced by pretreatment with gadolinium chloride and clodronate liposomes. Mediator mRNA expression was determined by real-time RT-PCR. Leukocyte extravasation was investigated in muscularis whole-mounts by immunohistochemistry. In vitro circular muscle contractility was assessed in a standard organ bath. Statistical analysis: unpaired Student t test, p < 0.05, mean ± SEM. Results: Organ harvesting and ischemia/reperfu-sion induce leukocyte recruitment and an increase in inflammatory mRNA expression in the intestinal muscularis (IL-6: 12217 fold, MCP-1: 62 fold, ICAM-1: 12 fold, COX-2: 8 fold, iNOS: 150 fold). Although organ harvesting in cold ischemia prevented early inflammatory gene expression, peak expression at 3 h reperfusion was not changed by modification of organ harvesting technique. The inflammatory response within the transplanted muscularis was associated with a significant impairment of smooth muscle contractile activity, compared to controls (1.1 ± 0.3 vs. 2.9 ± 0.2 g/mm2/s at 100 umol/1). In contrast, macrophage depletion prevented the inflammatory response in the transplanted muscularis and smooth muscle strips presented with significantly improved contractile activity (2.5 ± 0.2 g/mm2/s at 100 umol/1). Conclusions: Intestinal manipulation during organ harvesting initiates a functionally relevant molecular and cellular inflammatory response within the intestinal muscularis that is massively potentiated during the reperfusion period. Resident muscularis macrophages play a key role in initiating this inflammatory response.