Metabolic Profiles in Urine Reflect Nephrotoxicity of Sirolimus and Cyclosporine following Rat Kidney Transplantation

摘要

Background: Cyclosporine and/or sirolimus impair recovery of renal transplants. This study examines the changes in urine metabolite profiles as surrogate markers of renal cell metabolism and function after cyclosporine and/or sirolimus treatment employing a rat kidney transplantation model. Methods: Using inbred Lewis rats, kidneys were transplanted into bilaterally nephrectomized recipients followed by treatment with either CsA (cyclosporine) 10, Rapa (sirolimus) 1, CsA10/Rapa1 or CsA25/Rapa1 mg/kg/day for 7 days. On day 7, urine was analyzed by ~1H-NMR spectroscopy. Blood and kidney tissue drug concentrations, tissue high-energy compounds (including ATP, ADP) and oxidative stress markers (15-F_(2t)-isoprostanes) in urine were measured by HPLC mass spectrometry. Results: Changes in urine metabolites followed the order Rapal < CsA10 < CsA10/Rapa1 < CsA25/ Rapa1. Compared with controls, CsA25/Rapa1 showed the greatest changes (creatinine -36%, succinate -57%, citrate -89%,alpha-ketoglutarate -75%, creatine +498%, trimethyl-amine +210% and taurine +370%). 15-F_(2t)-isoprostane concentrations in urine increased in the combined immuno-suppressant-treated animals ([CsA25/Rapa1]: 795 ± 222, [CsA10/Rapa1]: 475 ± 233 pg/mg/creatinine) as compared with controls (165 ± 78 pg/mg creatinine). Rapa concentration in blood and tissues increased in the combined treatment (blood: 31 ± 8 ng/ml, tissue: 1.3 ± 0.4 ng/mg) as compared with monotherapy (blood: 14 ± 8 ng/ml, tissue: 0.35 ± 0.15 ng/mg). Drug blood concentrations correlated with isoprostane urine concentrations, which correlated negatively with citrate, a-ketoglutarate and creatinine concentrations in urine. Only CsA25/Rapa1 significantly reduced high-energy metabolite concentrations in transplant kidney tissue (ATP -55%, ADP -24%). Conclusion: Immunosuppressant drugs induce changes in urine metabolite patterns, suggesting that immunosuppressant-induced oxidative stress is an early event in the development of nephrotoxicity. Urine 15-F_(2t)-isoprostane concentrations and metabolite profiles may be sensitive markers of immunosuppressant-induced nephrotoxicity.