Testing OKN-007 as a potential intervention for ALS

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Amyotrophic lateral sclerosis (ALS) is a debilitating disease with currently no effective treatments. The goal of this proposal is to define the potential effectiveness of and mechanism of action of a promising new compound, OKN-007, that we have recently found to have neuroprotective effects in motor neurons in aging and in preliminary studies in an ALS mutant mouse model. Our recent studies in aging and sarcopenia have led us to focus on interventions targeted to preserving motor neuron health to reduce loss of innervation and NMJ disruption and therefore improve muscle outcomes in aging. To this end, we have exciting preliminary data using OKN-007, small molecule that reduces loss of motor neurons in aging mice. OKN-007 is a nitrone derivative of PBN (α-phenyl-N-tert-butyl-nitrone), a spin trap that has previously been shown to have beneficial effects in cancer and other pathologies. Nitrone compounds have known antioxidant and anti-inflammatory properties, and OKN-007 has neuroprotective effects in traumatic brain injury, in focal ischemia/stroke and in hearing loss. Our exciting preliminary data in aging mice show that OKN-007 can reduce motor neuron loss, reduce denervation in hindlimb muscle and reduce loss of gastrocnemius muscle mass in older mice. These findings led us to hypothesize that OKN-007 may also reduce motor neuron death and delay disease progression in ALS. Indeed, we are encouraged by our preliminary data that show a preservation of motor neuron number in the spinal cord and a delay in disease progression in the G93A ALS mouse model treated with OKN-007. The goal of this pilot project is to confirm these preliminary findings and test our hypothesis that OKN-007 can preserve motor neuron loss in ALS and delay disease progression. In Aim 1, we will determine the effect of OKN-007 treatment on motor neuron and skeletal muscle outcomes in disease progression and survival in the G93A mutant mouse model of ALS. Cohorts of control and G93A mice will be treated with OKN-007 in drinking water beginning at 30 days of age, at disease onset (95 days), or at 3 weeks post-onset (115 days) to determine preventative and therapeutic effects of the treatment. Mice will weighed and evaluated for disease score and progression beginning at 60 days of age. Using spinal cord from control and G93A mice, we will measure motor neuron number, inflammatory markers, oxidative damage and activation of cell death, known alterations in disease progression in ALS. Mice will be sacrificed at 145 days of age, prior to disease end stage. To assess known ALS mediated muscle phenotypes, we will measure grip strength starting 60 days of age and NMJ morphology and innervation status will be measured at 145 days, as well as markers of denervation in skeletal muscle and muscle atrophy. Parallel cohorts of mice will be set up to measure survival in response to drug treatment once we determine the most effective dose. In Aim 2, we will identify potential mechanisms of action for OKN-007 in motor neuron maintenance and survival by measuring the effect of OKN-007 on gene expression using RNA seq analysis in spinal cord motor neurons from mice in Aim 1. These studies will provide important information on the mechanism of action of OKN-007 and help to establish whether OKN-007 may be a good candidate for treatment to maintain motor neuron health in ALS patients.