Prevention of chronic rejection by pravastatin in a rat kidney transplant model

Background. Pravastatin when administered with cyclosporine (CsA) has been shown to ameliorate transplant vasculopathy in the clinical setting. Previously we showed that pravastatin prevents chronic rejection in rat cardiac and liver transplant models. Here we determine whether pravastatin prevents chronic rejection in a rat renal allograft model. Methods. Orthotopic renal transplantations were performed using Fisher 344 rats as donors and Lewis rats as recipients. Recipients were treated with low-dose CsA for 10 days to prevent acute rejection. Recipients were divided into three groups: CsA, CsA + pravastatin, and syngeneic. Renal function was assessed by serum creatinine level at day 130. Allografts were evaluated by histology and immunohistochemistry. Serum levels of alloantibodies we're measured by flow cytometry. Intragraft cytokine mRNA expression was determined by semiquantitative reverse transcriptase-polymerase chain reaction. Intragraft levels of the antiapoptotic Bag-1 gene were measured by Western blot. Results. Unlike allografts from the pravastatin group, control allografts demonstrated glomerulosclerosis, vascular obliteration, tubular atrophy, and interstitial fibrosis. Serum creatinine levels and graft infiltration of T cells and macrophages in the pravastatin-treated animals were significantly lower. Intragraft cytokines showed a T helper 2 polarization and decreased transforming growth factor-beta in the pravastatin group. Intragraft expression of Bag-1 was increased in the pravastatin group. Conclusion This study demonstrates the ability of pravastatin to inhibit chronic rejection in rat renal allografts. Pravastatin's pleiotropic effects of reducing intragraft inflammatory cytokines, inhibiting immune cell infiltration, and causing up-regulation of the antiapoptotic gene Bag-1 suggest that its ability to prevent transplant chronic rejection may be multifactorial.