Metabolic profiles in urine reflect nephrotoxicity of sirolimus and cyclosporine following rat kidney transplantation.
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 (1)H-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 Rapa1 < 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%, trimethylamine +210% and taurine +370%). 15-F(2t)-isoprostane concentrations in urine increased in the combined immunosuppressant-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, alpha-ketoglutarate and creatinine concentrations in urine. Only CsA25/Rapa1 significantly reduced high-energy metabolite concentrations in transplant kidney tissue (ATP -55%, ADP -24%).


CONCLUSIONS
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.
Schmitz
Volker
V
Department of General, Visceral and Transplantation Surgery, Charité, Berlin, Germany. volker.schmitz@charite.de
Klawitter
Jost
J
Bendrick-Peart
Jamie
J
Schoening
Wenzel
W
Puhl
Gero
G
Haschke
Manuel
M
Klawitter
Jelena
J
Consoer
Jeff
J
Rivard
Christopher J
CJ
Chan
Laurence
L
Tran
Zung V
ZV
Leibfritz
Dieter
D
Christians
Uwe
U
D000818:Animals; D015415:Biomarkers / Q000652:urine; D016572:Cyclosporine / Q000633:toxicity* / Q000652:urine*; D016030:Kidney Transplantation / Q000379:methods; D008297:Male; D055442:Metabolome / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011917:Rats, Inbred Lew; D020123:Sirolimus / Q000633:toxicity* / Q000652:urine*
D015415:Biomarkers; D016572:Cyclosporine; D020123:Sirolimus