Chronic rejection after rat liver-small bowel transplantation

The pathogenesis of chronic rejection after small bowel transplantation is still not well understood. Statistically, however, chronic allograft dysfunction in humans seems less frequent if small bowel is transplanted in combination with a liver. Therefore, the aim of this study is to establish an experimental model for investigation of this phenomenon. Results after combined liver-small bowel transplantation (with or without immunosuppression) have been compared with isolated small bowel transplantation in the Brown Norway-Lewis (BN-LEW) rat strain combination. Signs of rejection were evaluated by histology, immunohistochemistry, and the rate of parenchymal apoptosis in the allografts. Graft survival after liver-small bowel transplantation was prolonged in concomitant liver-small bowel transplantation as compared with small bowel transplantation alone. Furthermore, not only less immunosuppression was needed to establish long-term acceptance after a transient acute rejection, but tolerance was established after liver-small bowel transplantation. However, without initial immunosuppression, a more severe acute rejection crisis resulted in chronic rejection even after liver-small bowel transplantation. Concordant to results after human renal transplantation, the degree of the early parenchymal injury in the allografts seems to be a reliable predictor for the late onset of chronic rejection.