Different effects of tacrolimus and cyclosporine on PDGF induction and chronic allograft injury: Evidence for improved kidney graft outcome

• Increased fibrosis has been reported in renal transplants under CsA compared to Tac
• PDGF is one of the best-characterized fibrogenic growth factors in renal disease
• Tac ameliorated markedly renal rejection changes and PDGF induction compared to CsA
• The decreased PDGF induction by Tac may be beneficial for the kidney graft outcome

IntroductionChronic allograft injury is the most frequent cause of long-term kidney allograft loss. Cyclosporine (CsA) nephrotoxicity is an important factor contributing to graft loss. Increased fibrosis has been reported in renal transplants under CsA as compared with tacrolimus (Tac). Platelet-derived growth factor (PDGF) is a well-characterized fibrogenic growth factor in renal disease.ObjectiveHere we investigated the effect of Tac on kidney grafts and PDGF expression both early after transplantation as well as during long-term follow-up of rat renal allografts, and compared it to CsA. Tac and CsA were also studied on PDGF secretion in macrophages in vitro.Materials and methodsKidney allografts were immunosuppressed with Tac or CsA. Grafts were analyzed by histology and immunohistochemistry. ELISA was used to measure PDGF-levels in Tac and CsA-treated macrophage cultures.ResultsTac ameliorated markedly both acute and chronic changes, whereas moderate to intense histological changes were seen in CsA-treated allografts. Tac also significantly inhibited PDGF expression compared to CsA. At clinically adjusted concentration CsA induced PDGF in macrophages whereas Tac did not.DiscussionTac may be less fibrogenic than CsA by decreasing PDGF expression in kidney grafts as well as in macrophages. Data presented here suggests that decreased PDGF induction by Tac may be beneficial for later outcome of the kidney graft.