The Effect of Immunosuppression on Peritoneal Adhesions Formation After Small Bowel Transplantation in Rats

Background: The reported incidence of adhesion related small bowel obstruction after abdominal organ transplantation is considerably lower than other abdominal procedures. The purpose of the study was to investigate the influence of immunosuppression on peritoneal adhesion formation after intestinal transplantation in rats. Methods: Four groups of rats (n = 6) underwent small bowel intestinal transplantation in syngeneic (Groups A, B) and allogeneic (Groups C, D) combinations. Groups B and D received tacrolimus immunosuppression 1 mg/kg/d. Animals were euthanized on postoperative day 7, and the total adhesion score (TAS), tissue hydroxyproline content (HPC), TGF-β mRNA expression levels and histology were examined. Results: All of the animals in Group C showed severe histological (Grade III) acute cellular rejection. There were no histological signs of rejection in Group D. A significant reduction in TAS was observed in tacrolimus treated animals in both syngeneic and allogeneic combinations (Groups B and D), compared with controls (Groups A and C) (P < 0.001 and P < 0.01, respectively). TAS results correlated with the differences in TGF-β levels that showed significant reduction when each immunosuppressed group was compared with its nontreated counterpart, i.e., (Groups B versus A, P < 0.05, and Groups D versus C, P < 0.01). TGF-β levels were significantly high in the rejection group (C) and correlated with the intense adhesion formation that was demonstrated in that group. Group C was also the only group in which a significant elevation in HPC was demonstrated (P < 0.001). Conclusion: Intense adhesion formation occurs during early posttransplant acute rejection. Postsurgical adhesion formation is significantly reduced in immunosuppressed rats after intestinal transplantation.