The effect of FK778 on the progression of chronic allograft nephropathy in a rat model.

Background. Chronic allograft nephropathy (CAN) still belongs to the leading causes of graft loss over the long term. The leflunomide derivative FK778 is a novel immunosuppressant with improved pharmacokinetic properties that effectively prolonged graft survival in several transplantation models. In the present study, we investigated the effects of FK778 at different phases after transplantation on the progression of CAN. Methods. Fisher 344 kidneys were orthotopically transplanted into Lewis recipients. Recipients were treated with FK778 (5 mg/kg/day) over different time periods (early: days 0–10 only, continuous: day 0 to week 24, or late: weeks 16–24 only posttransplantation). Proteinuria was measured every 4 weeks, whereas grafts were harvested at 24 weeks posttransplantation for morphological and immunohistochemical analysis as well as transforming growth factor–β and platelet derived growth factor–B chain expression. Results. Continuous treatment with FK778 ameliorated the progression of CAN, whereas late treatment reduced proteinuria and resulted in a similar grade of CAN as compared to animals with continuous treatment. In contrast, FK778 given only during the early phase after transplantation had no effect on the progression of CAN as compared to controls. Conclusion. In summary, FK778 is a potent immunosuppressive drug that can delay the progression of CAN, even when given at later stages after transplantation.