The Nonimmunosuppressive Cyclosporin Analogs NIM811 and UNIL025 Display Nanomolar Potencies on Permeability Transition in Brain-Derived Mitochondria

Abstract

Cyclosporin A (CsA) is highly neuroprotective in several animal models of acute neurological damage and neurodegenerative disease with inhibition of the mitochondrial permeability transition (mPT) having emerged as a possible mechanism for the observed neuroprotection. In the present study, we have evaluated two new nonimmunosuppressive cyclosporin analogs NIM811 (Novartis) and UNIL025 (Debiopharm) for their ability to inhibit mPT in rat brain-derived mitochondria. Both NIM811 and UNIL025 were found to be powerful inhibitors of calcium-induced mitochondrial swelling under energized and deenergized conditions, and the maximal effects were identical to those of native CsA. The potencies of mPT inhibition by NIM811 and UNIL025 were stronger, with almost one order of magnitude higher potency for UNIL025 compared to CsA, correlating to their respective inhibitory action of cyclophilin activity. These compounds will be instrumental in the evaluation of mPT as a central target for neuroprotection in vivo.

Targeting Mitochondrial Function for the Treatment of Acute Spinal Cord Injury

“…NIM811 (N-methyl-isoleucine-cyclosporin) is a cyclosporin analog that also binds to Cyp-D and blocks mPT at nanomolar concentrations in brain mitochondria [112][113][114]. NIM811 was originally developed to be a less toxic alternative to CsA, but the modifications made to the cyclosporin structure eliminated the immunosuppressive properties mediated by calcineurin inhibition.…”

Calcium-induced generation of reactive oxygen species in brain mitochondria is mediated by permeability transition

“…The populational extent of swelling was calculated as calcium-induced decrease in light scattering compared to that by the ionophore alamethicin (10 µg/ml) as described previously [27]. Experiments evaluating mPT inhibition by CsA and 21 natural or semi-synthetic cyclosporin analogs were performed under de-energized conditions as described earlier [27,28]. Mitochondria were incubated in the presence of 10 nM to 5 µM of CsA-analogs or vehicle and the extent of light scattering decrease was compared to that by alamethicin after 5 min of Ca 2+ exposure.…”

“…This enabled evaluation of a wide range of mPT inhibition by the cyclosporin analogs. Analogs 1-15 (identity given in Table 1) were evaluated in both mouse brain and mouse liver mitochondria, analogs [16][17][18][19] in mouse liver mitochondria only and NIM811 and UNIL025 (renamed DEBIO-025) were evaluated previously in rat brain mitochondria [28]. To enable inter-experimental comparisons of all analogs their relative inhibition of calcium-induced mPT was compared to that of CsA, all at 1 µM.…”

In mito veritas ?

“…Ceci permet d'envisager un second impact pharmacologique du médicament qui bloquerait la formation du pore PTP, par un mécanisme indépendant de la calcineurine [18]. En substituant sur la molécule de CsA le résidu sarcosine en position 3 par une N-méthyle-D-ala, et le résidu N-méthyle-leucine en position 4 par un reste N-éthyle-val, les chimistes de la firme DebioPharm de Lausanne (Suisse) sont justement parvenus à obtenir un analogue (Debio-025) qui ne cible plus que CypD, ce qui en fait un médi-cament purement mitochondrial, dépourvu de tout effet immunosuppresseur [19]. Pour démontrer que CypD est une cible thérapeutique intéressante dans certaines DM, Millay et al [2] ont dans un premier temps croisé des souris Scgd -/-ou des souris Lama2 -/-(voir Tableau I) avec des souris dont le gène de CypD a été invalidé par KO de topographie subcellulaire très variées.…”

“…Ceci permet d'envisager un second impact pharmacologique du médicament qui bloquerait la formation du pore PTP, par un mécanisme indépendant de la calcineurine [18]. En substituant sur la molécule de CsA le résidu sarcosine en position 3 par une N-méthyle-D-ala, et le résidu N-méthyle-leucine en position 4 par un reste N-éthyle-val, les chimistes de la firme DebioPharm de Lausanne (Suisse) sont justement parvenus à obtenir un analogue (Debio-025) qui ne cible plus que CypD, ce qui en fait un médi-cament purement mitochondrial, dépourvu de tout effet immunosuppresseur [19] [9][10][11][12]. Ce pore est constitué par l'assemblage de trois protéines : la protéine VDAC (voltage-dependent transporter) située dans la membrane mitochondriale externe, la protéine ANT (adenine nucleotide translocase) dans la membrane mitochondriale interne et la protéine CypD (cyclophiline-D) dans l'espace mitochondrial interne [13,14].…”