tro-40303 and Disease-Models--Animal

Although reperfusion injury has been shown to be responsible for cardiomyocytes death after an acute myocardial infarction, there is currently no drug on the market that reduces this type of injury. TRO40303 is a new cardioprotective compound that was shown to inhibit the opening of the mitochondrial permeability transition pore and reduce infarct size after ischemia-reperfusion in a rat model of cardiac ischemia-reperfusion injury.. In the rat model, the therapeutic window and the dose effect relationship were investigated in order to select the proper dose and design for clinical investigations. To evaluate post-ischemic functional recovery, TRO40303 was tested in a model of isolated rat heart. Additionally, TRO40303 was investigated in a Phase I randomized, double-blind, placebo controlled study to assess the safety, tolerability and pharmacokinetics of single intravenous ascending doses of the compound (0.5 to 13 mg/kg) in 72 healthy male, post-menopausal and hysterectomized female subjects at flow rates from 0.04 to 35 mL/min (EudraCT number: 2010-021453-39). This work was supported in part by the French Agence Nationale de la Recherche.. In the vivo model, TRO40303 reduced infarct size by 40% at 1 mg/kg and by 50% at 3 and 10 mg/kg given by intravenous bolus and was only active when administered before reperfusion. Additionally, TRO40303 provided functional recovery and reduced oxidative stress in the isolated rat heart model.These results, together with pharmacokinetic based allometry to human and non-clinical toxicology data, were used to design the Phase I trial. All the tested doses and flow rates were well tolerated clinically. There were no serious adverse events reported. No relevant changes in vital signs, electrocardiogram parameters, laboratory tests or physical examinations were observed at any time in any dose group. Pharmacokinetics was linear up to 6 mg/kg and slightly ~1.5-fold, hyper-proportional from 6 to 13 mg/kg.. These data demonstrated that TRO40303 can be safely administered by the intravenous route in humans at doses expected to be pharmacologically active. These results allowed evaluating the expected active dose in human at 6 mg/kg, used in a Phase II proof-of-concept study currently ongoing.

Topics: Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Healthy Volunteers; Humans; In Vitro Techniques; Liposomes; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Oxidative Stress; Oximes; Rats; Secosteroids; Sus scrofa; Translational Research, Biomedical

The translocator protein (TSPO) is located on the outer mitochondrial membrane where it is responsible for the uptake of cholesterol into mitochondria of steroidogenic organs. TSPO is also present in the heart where its role remains uncertain. We recently showed that TSPO ligands reduced infarct size and improved mitochondrial functions after ischaemia-reperfusion. This study, thus, sought to determine whether cholesterol could play a role in the cardioprotective effect of TSPO ligands.. In a model of 30 min coronary occlusion/15 min reperfusion in Wistar rat, we showed that reperfusion induced lipid peroxidation as demonstrated by the increase in conjugated diene and thiobarbituric acid reactive substance formation and altered mitochondrial function (decrease in oxidative phosphorylation and increase in the sensitivity of mitochondrial permeability transition pore opening) in ex-vivo isolated mitochondria. This was associated with an increase in mitochondrial cholesterol uptake (89.5 ± 12.2 vs. 39.9 ± 3.51 nmol/mg protein in controls, P < 0.01) and a subsequent strong generation of auto-oxidized oxysterols, i.e. 7α- and 7β-hydroxycholesterol, 7-ketocholesterol, cholesterol-5α,6α-epoxide, and 5β,6β-epoxide (+173, +149, +165, +165, and +193% vs. controls, respectively; P < 0.01). Administration of the selective TSPO ligand 4'-chlorodiazepam inhibited oxidative stress, improved mitochondrial function, and abolished both mitochondrial cholesterol accumulation and oxysterol production. This was also observed with the new TSPO ligand TRO40303.. These data suggest that 4'-chlorodiazepam inhibits oxidative stress and oxysterol formation by reducing the accumulation of cholesterol in the mitochondrial matrix at reperfusion and prevents mitochondrial injury. This new and original mechanism may contribute to the cardioprotective properties of TSPO ligands.

Topics: Animals; Benzodiazepinones; Biological Transport; Carrier Proteins; Cholesterol; Cytoprotection; Disease Models, Animal; Ligands; Lipid Peroxidation; Male; Membrane Fluidity; Membrane Potential, Mitochondrial; Mitochondria, Heart; Mitochondrial Membrane Transport Proteins; Mitochondrial Membranes; Mitochondrial Permeability Transition Pore; Myocardial Reperfusion Injury; Myocytes, Cardiac; Oxidative Phosphorylation; Oxidative Stress; Oximes; Protective Agents; Rats; Rats, Wistar; Receptors, GABA-A; Secosteroids; Thiobarbituric Acid Reactive Substances; Time Factors