Background: Intestinal transplantation is offered to patients with irreversible intestinal failure and life-threatening complications of parenteral nutrition. Ischaemia-reperfusion (I/R) injury to the intestine is universal following transplantation. Whilst I/R can occasionally result in graft failure, more commonly it results in intestinal dysmotility, often resulting in significant morbidity. The mechanism by which I/R results in dysmotility remains unclear.

 

Aims: The aim was to describe the histologic and molecular changes occurring in the human intestine following I/R injury in an attempt to elucidate mechanisms to explain post transplant dysmotility.

 

Methods: I/R was applied to a segment of jejunum (5-8 cm) in patients undergoing pancreaticoduodenectomy (Whipple’s procedure). Adjacent segments of intestine were isolated by a cutting stapler. One segment was subjected to vascular occlusion for 30 minutes, followed by a subsequent 30 minutes or 2 hours of reperfusion prior to the segment being removed. The adjacent region (control) had no vascular occlusion. Fresh tissue was processed for histology, immunohistochemistry and molecular analyses.

 

Results: 15 patients were included. 7 patient samples were exposed to 30 minutes reperfusion whilst 8 were exposed to 2 hours. With 30 minutes reperfusion histological examination revealed structural damage centred at the tips of the villi, with the surface of the epithelium separated from the underlying tissue or occasionally sloughed off. There was significant villus neutrophil and macrophage infiltration (P<0.05) and acute inflammation present in and around the venules of the longitudinal muscle and serosal areas, but not around the submucosal vessels. At 2 hours the same histological trend was seen. The major difference was further infiltration of neutrophils and macrophages into the serosal layer and longitudinal muscle, with conspicuous neutrophil aggregates around myenteric ganglia (ganglionitis). Concomitant with histological features, mRNA levels of major inflammatory cytokines show significant increase in external muscle layers of the segments subjected to I/R including IL-1 (P<0.0001), IL-6 (P<0.0001) and IL-8 (P<0.001). Similar changes were not seen in the mucosa.

 

Conclusion: This novel study clearly shows in human intestine that following I/R there is a rapid and targeted immune cell infiltration of the serosal and external muscle layers associated with significant local up-regulation of inflammatory cytokines. Within 2 hours ganglionitis is present. These findings highlight the exquisite sensitivity of the intestine to relatively brief periods of I/R and the need to further characterise the extremely complex association between I/R injury, inflammation and damage to intestinal ganglia.