The novel immunosuppressant SDZ‐RAD protects rat brain slices from cyclosporine‐induced reduction of high‐energy phosphates

Abstract

1 SDZ-RAD, 40-O-(2-hydroxyethyl)-rapamycin, is a novel macrolide immunosuppressant. Because of its synergistic interaction, SDZ-RAD is under clinical investigation as immunosuppressant in combination with cyclosporine after organ transplantation. Neurotoxicity is a critical side-e ect of cyclosporine. 2 We studied the e ect of SDZ-RAD and its combination with cyclosporine on high-energy phosphates, phosphocreatine (PCr) and nucleoside triphosphates (NTP), in brain slices using 31 Pmagnetic resonance spectroscopy (MRS). 3 Cyclosporine signi®cantly reduced high-energy phosphates after 2 h in a dose-dependent manner (100 mg l 71 : 93+3% of control (NTP), 91+3% (PCr); 500 mg l 71 : 84+2% (NTP), 73+2 (PCr); 5000 mg l 71 : 68+3% (NTP), 55+5% (PCr); n=6; P50.02). 4 In contrast, after perfusion for 2 h, SDZ-RAD (500 mg l 71 and 5000 mg l 71 ) signi®cantly increased high-energy phosphate concentrations in the brain slices (P50.02). Even at the lowest concentration, SDZ-RAD protected brain energy metabolism against cyclosporine toxicity: 100 mg l 71 SDZ-RAD+5000 mg l 71 cyclosporine: 86+3% (NTP), 83+7% (PCr), n = 3, P50.03 compared to cyclosporine alone. 5 As evaluated using an algorithm based on Loewe isobolograms, the e ects of SDZ-RAD/ cyclosporine combinations on brain energy reduction were antagonistic. Both drugs were found in mitochondria using h.p.l.c-MS analysis. 6 We conclude that cyclosporine inhibits mitochondrial high-energy phosphate metabolism, which can be antagonized by SDZ-RAD.

Immunosuppressant Neurotoxicity in Rat Brain Models: Oxidative Stress and Cellular Metabolism

“…In contrast, RAD antagonized CsA-related negative effects in rat brain energy state (12, 21). As of to date, there is little information regarding the effects of SRL and RAD on the ROS-balance.…”

Proteo‐Metabolomic Strategies in the Future of Drug Development

“…Meanwhile there is evidence that mTOR indirectly regulates glycolysis [315]. Interestingly, the studies by Serkova et al indicated that the structurally related everolimus has the potential to antagonize cyclosporine toxicity although it is also an mTOR inhibitor [310,311]. In the meantime, these results could be translated to the rat kidney and the suggested combination of everolimus and ultra-low dose calcineurin inhibitors is assessed in clinical trials.…”

“…A good example for how NMR-based metabolomics approaches can efficiently be combined to identify toxicodynamic molecular mechanisms is the work by Serkova et al assessing the negative effects of immunosuppressants on the central nervous system [306][307][308][309][310][311][312][313][314]. The time-and dose-dependent effects of the calcineurin inhibitor cyclosporine alone and in combination with inhibitors of the mammalian target of rapamycin (mTOR) sirolimus and everolimus were systematically evaluated using a combination of 1 H-NMR metabolic profiling, 31 P-NMR to study high-energy phosphate metabolism, 13 C-NMR after exposure to 13 C-labeled tracers, and real-time monitoring of time-dependent metabolic changes in perfused ex vivo brain slices using a wide-bore NMR scanner [306].…”

The novel calcineurin inhibitor ISA247: a more potent immunosuppressant than cyclosporine in vitro

“…It is generally accepted that many toxic side effects are directly related to inhibition of calcineurin [1,2,3,4]. Recent studies suggest that CsA toxicity may be also attributable to other factors, such as induction of TGFb [5] or inhibition of mitochondrial high-energy phosphate metabolism [6,7], implying that there might be a disassociation between calcineurin inhibition and toxicity. Therefore, it may be theoretically possible to develop calcineurin inhibitors that are less toxic but are effective immunosuppressants.…”