Olesoxime (TRO19622): A Novel Mitochondrial-Targeted Neuroprotective Compound

pharmaceutical

Antisera to bovine oligodendroglia raised in guinea pigs bind to surface of rat oligodendroglia and Schwann cells

Antisera against bulk isolated bovine oligodendrocytes was raised in 2 guinea pigs (GPaBO). The sera bound only to surface of rat oligodendrocytes in dissociated rat corpus callosum and cerebellar cultures and only to surface of Schwann cells in primary and secondary sciatic nerve and dorsal root ganglia cultures as determined by indirect immunofluorescence. No cells in muscle or retinal cultures bound the guinea pig antisera. The shared antigen does not seem to be either galactocerebroside (GalC) or a myelin basic protein. GPaBO can serve as a useful marker in double-label experiments to identify oligodendrocytes and Schwann cells in dissociated cultures

Olesoxime accelerates myelination and promotes repair in models of demyelination.

International audienceOBJECTIVE: Multiple sclerosis is a neurodegenerative disease characterized by episodes of immune attack of oligodendrocytes leading to demyelination and progressive functional deficit. One therapeutic strategy to address disease progression could consist in stimulating the spontaneous regenerative process observed in some patients. Myelin regeneration requires endogenous oligodendrocyte progenitor migration and activation of the myelination program at the lesion site. In this study, we have tested the ability of olesoxime, a neuroprotective and neuroregenerative agent, to promote remyelination in the rodent central nervous system in vivo. METHODS: The effect of olesoxime on oligodendrocyte progenitor cell (OPC) differentiation and myelin synthesis was tested directly in organotypic slice cultures and OPC-neuron cocultures. Using naive animals and different mouse models of demyelination, we morphologically and functionally assessed the effect of the compound on myelination in vivo. RESULTS: Olesoxime accelerated oligodendrocyte maturation and enhanced myelination in vitro and in vivo in naive animals during development and also in the adult brain without affecting oligodendrocyte survival or proliferation. In mouse models of demyelination and remyelination, olesoxime favored the repair process, promoting myelin formation with consequent functional improvement. INTERPRETATION: Our observations support the strategy of promoting oligodendrocyte maturation and myelin synthesis to enhance myelin repair and functional recovery. We also provide proof of concept that olesoxime could be useful for the treatment of demyelinating diseases

Early deficits in glycolysis are specific to striatal neurons from a rat model of huntington disease.

In Huntington disease (HD), there is increasing evidence for a link between mutant huntingtin expression, mitochondrial dysfunction, energetic deficits and neurodegeneration but the precise nature, causes and order of these events remain to be determined. In this work, our objective was to evaluate mitochondrial respiratory function in intact, non-permeabilized, neurons derived from a transgenic rat model for HD compared to their wild type littermates by measuring oxygen consumption rates and extracellular acidification rates. Although HD striatal neurons had similar respiratory capacity as those from their wild-type littermates when they were incubated in rich medium containing a supra-physiological glucose concentration (25 mM), pyruvate and amino acids, respiratory defects emerged when cells were incubated in media containing only a physiological cerebral level of glucose (2.5 mM). According to the concept that glucose is not the sole substrate used by the brain for neuronal energy production, we provide evidence that primary neurons can use lactate as well as pyruvate to fuel the mitochondrial respiratory chain. In contrast to glucose, we found no major deficits in HD striatal neurons' capacity to use pyruvate as a respiratory substrate compared to wild type littermates. Additionally, we used extracellular acidification rates to confirm a reduction in anaerobic glycolysis in the same cells. Interestingly, the metabolic disturbances observed in striatal neurons were not seen in primary cortical neurons, a brain region affected in later stages of HD. In conclusion, our results argue for a dysfunction in glycolysis, which might precede any defects in the respiratory chain itself, and these are early events in the onset of disease

Differences in the profile of protection afforded by TRO40303 and mild hypothermia in models of cardiac ischemia/reperfusion injury

The mode of protection against cardiac reperfusion injury by mild hypothermia and TRO40303 was investigated in various experimental models and compared to MitoQ in vitro. In isolated cardiomyocytes subjected to hypoxia/reoxygenation, TRO40303, MitoQ and mild hypothermia delayed mPTP opening, inhibited generation of mitochondrial superoxide anions at reoxygenation and improved cell survival. Mild hypothermia, but not MitoQ and TRO40303, provided protection in a metabolic starvation model in H9c2 cells and preserved respiratory function in isolated rat heart mitochondria submitted to anoxia/reoxygenation. In the Langendorff-perfused rat heart, only mild hypothermia provided protection of hemodynamic function and reduced infarct size following ischemia/reperfusion. In biopsies from the left ventricle of pigs subjected to in vivo occlusion/reperfusion, TRO40303 specifically preserved respiratory functions in the peri-infarct zone whereas mild hypothermia preserved both the ischemic core area and the peri-infarct zones. Additionally in this pig model, only hypothermia reduced infarct size. We conclude that mild hypothermia provided protection in all models by reducing the detrimental effects of ischemia, and when initiated before occlusion, reduced subsequent reperfusion damage leading to a smaller infarct. By contrast, although TRO40303 provided similar protection to MitoQ in vitro and offered specific protection against some aspects of reperfusion injury in vivo, this was insufficient to reduce infarct size