The calcineurin inhibitors, (CIs) cyclosporinen, and tacrolimus are the basis of most immunosuppressive protocols after organ transplantation. The propensity of these agents to ultimately damage the very organs they were intended to protect, especially the kidney, was always recognized, but largely tolerated due to their impressive ability to improve short-term outcomes. With the target-of-rapamycin (TOR) inhibitor sirolimus, an equally potent immunosuppressant that itself is lacking the most important side effects of Cls, such as nephrotoxicity and neurotoxicity, has become available. The combination of sirolimus with CIs is attractive since it results in synergistic immunosuppressive activity. Although devoid of nephrotoxicity when administered alone, sirolimus unexpectedly enhanced cyclosporine nephrotoxicity in clinical studies. The exact biochemical mechanisms underlying immunosuppressant toxicity alone and in combination is still poorly understood. Based on our previous work, we hypothesize that both, CI-induced mitochondrial dysfunction in blood vessel endothelium leading to vasoconstriction and direct negative effects on mitochondrial kidney energy metabolism, cause CI nephrotoxicity and that TOR inhibitors enhance CI nephrotoxicity by enhancing the negative effects of CIs on mitochondrial energy metabolism. To test our hypothesis, we propose to systematically study the effect of calcineurin inhibitors and/or sirolimus on kidney and arterial endothelial cell metabolism in the rat in vivo using magnetic resonance spectroscopy (MRS) and to correlate those with histological, functional and molecular changes known to be typical for CI nephrotoxicity. We will identify the biochemical mechanisms using MRS, will evaluate the role of cyclophilin and calcineurin in the observed changes, will compare different in vivo kidney toxicity models, will evaluate the contribution of pharmacodynamic and pharmacokinetic drug interactions when calcineurin and TOR inhibitors are combined and will evaluate differences in the negative effects of the study drugs and their combinations on transplant kidneys (exposed to ischemia/reperfusion) versus non-transplant kidneys. The results of our studies (a) will give important new insights in the biochemical mechanisms underlying toxicity of immunosuppressants and their combinations, (b) will identify surrogate markers for immunosuppressant toxicity (e.g. the potential use of isoprostanes for clinical pharmacodynamic monitoring of CI toxicity) and (c) will propose assays to test interactions of immunosuppressants in terms of toxicity during pre-clinical development. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK065094-02
Application #
6772392
Study Section
Alcohol and Toxicology Subcommittee 4 (ALTX)
Program Officer
Flessner, Michael Francis
Project Start
2003-07-15
Project End
2007-04-30
Budget Start
2004-05-01
Budget End
2005-04-30
Support Year
2
Fiscal Year
2004
Total Cost
$295,939
Indirect Cost
Name
University of Colorado Denver
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
041096314
City
Aurora
State
CO
Country
United States
Zip Code
80045
Klawitter, Jelena; Klawitter, Jost; Schmitz, Volker et al. (2014) Mycophenolate mofetil enhances the negative effects of sirolimus and tacrolimus on rat kidney cell metabolism. PLoS One 9:e86202
Klawitter, Jelena; Klawitter, Jost; Schmitz, Volker et al. (2012) Low-salt diet and cyclosporine nephrotoxicity: changes in kidney cell metabolism. J Proteome Res 11:5135-44
Bohra, Rahul; Schöning, Wenzel; Klawitter, Jelena et al. (2012) Everolimus and sirolimus in combination with cyclosporine have different effects on renal metabolism in the rat. PLoS One 7:e48063
Christians, Uwe; Klawitter, Jost; Klawitter, Jelena et al. (2011) Biomarkers of immunosuppressant organ toxicity after transplantation: status, concepts and misconceptions. Expert Opin Drug Metab Toxicol 7:175-200
Strom, Tobin; Shokati, Touraj; Klawitter, Jost et al. (2011) Structural identification of SAR-943 metabolites generated by human liver microsomes in vitro using mass spectrometry in combination with analysis of fragmentation patterns. J Mass Spectrom 46:615-24
Steudel, Wolfgang; Dingmann, Colleen; Zhang, Yan-Ling et al. (2011) Randomized, double-blind, placebo-controlled, single intravenous dose-escalation study to evaluate the safety, tolerability, and pharmacokinetics of the novel coronary smooth muscle cell proliferation inhibitor Biolimus A9 in healthy individuals. J Clin Pharmacol 51:29-39
Klawitter, Jelena; Haschke, Manuel; Shokati, Touraj et al. (2011) Quantification of 15-F2t-isoprostane in human plasma and urine: results from enzyme-linked immunoassay and liquid chromatography/tandem mass spectrometry cannot be compared. Rapid Commun Mass Spectrom 25:463-8
Klawitter, Jelena; Gottschalk, Sven; Hainz, Carsten et al. (2010) Immunosuppressant neurotoxicity in rat brain models: oxidative stress and cellular metabolism. Chem Res Toxicol 23:608-19
Klawitter, Jost; Klawitter, Jelena; Kushner, Erich et al. (2010) Association of immunosuppressant-induced protein changes in the rat kidney with changes in urine metabolite patterns: a proteo-metabonomic study. J Proteome Res 9:865-75
Schmitz, Volker; Klawitter, Jost; Bendrick-Peart, Jamie et al. (2009) Metabolic profiles in urine reflect nephrotoxicity of sirolimus and cyclosporine following rat kidney transplantation. Nephron Exp Nephrol 111:e80-91

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