Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive loss of motor neurons. Using unbiased transcript profiling in an ALS mouse model, we identified a role for the co-stimulatory pathway, a key regulator of immune responses. Furthermore, we observed that this pathway is upregulated in the blood of 56% of human patients with ALS. A therapy using a monoclonal antibody to CD40L was developed that slows weight loss, delays paralysis and extends survival in an ALS mouse model. This work demonstrates that unbiased transcript profiling can identify cellular pathways responsive to therapeutic intervention in a preclinical model of human disease.
BackgroundIn any animal model of human disease a positive control therapy that demonstrates efficacy in both the animal model and the human disease can validate the application of that animal model to the discovery of new therapeutics. Such a therapy has recently been reported by Fornai et al. using chronic lithium carbonate treatment and showing therapeutic efficacy in both the high-copy SOD1G93A mouse model of familial amyotrophic lateral sclerosis (ALS), and in human ALS patients.Methodology/Principal FindingsSeeking to verify this positive control therapy, we tested chronic lithium dosing in a sibling-matched, gender balanced, investigator-blinded trial using the high-copy (average 23 copies) SOD1G93A mouse (n = 27–28/group). Lithium-treated mice received single daily 36.9 mg/kg i.p. injections from 50 days of age through death. This dose delivered 1 mEq/kg (6.94 mg/kg/day lithium ions). Neurological disease severity score and body weight were determined daily during the dosing period. Age at onset of definitive disease and survival duration were recorded. Summary measures from individual body weight changes and neurological score progression, age at disease onset, and age at death were compared using Kaplan-Meier and Cox proportional hazards analysis. Our study did not show lithium efficacy by any measure.Conclusions/SignificanceRigorous survival study design that includes sibling matching, gender balancing, investigator blinding, and transgene copy number verification for each experimental subject minimized the likelihood of attaining a false positive therapeutic effect in this standard animal model of familial ALS. Results from this study do not support taking lithium carbonate into human clinical trials for ALS.
The SOD1-G93A transgenic mouse is the most widely used animal model of amyotrophic lateral sclerosis (ALS). At ALS TDI we developed a phenotypic screening protocol, demonstrated in video herein, which reliably assesses the neuromuscular function of SOD1-G93A mice in a quick manner. This protocol encompasses a simple neurological scoring system (NeuroScore) designed to assess hindlimb function. NeuroScore is focused on hindlimb function because hindlimb deficits are the earliest reported neurological sign of disease in SOD1-G93A mice. The protocol developed by ALS TDI provides an unbiased assessment of onset of paresis (slight or partial paralysis), progression and severity of paralysis and it is sensitive enough to identify drug-induced changes in disease progression. In this report, the combination of a detailed manuscript with video minimizes scoring ambiguities and inter-experimenter variability thus allowing for the protocol to be adopted by other laboratories and enabling comparisons between studies taking place at different settings. We believe that this video protocol can serve as an excellent training tool for present and future ALS researchers.
Non-natively folded variants of superoxide dismutase 1 (SOD1) are thought to contribute to the pathogenesis of familial amyotrophic lateral sclerosis (ALS), however the relative toxicities of these variants are controversial. Here, we aimed to decipher the relationships between the different SOD1 variants (aggregated, soluble misfolded, soluble total) and the clinical presentation of ALS in the SOD1
G93A
mouse. Using a multi-approach strategy, we found that the CNS regions least affected by disease had the most aggregated SOD1. We also found that the levels of aggregated SOD1 in the spinal cord were inversely correlated with the disease progression. Conversely, in the most affected regions, we observed that there was a high soluble misfolded/soluble total SOD1 ratio. Taken together, these findings suggest that soluble misfolded SOD1 may be the disease driver in ALS, whereas aggregated SOD1 may serve to sequester the toxic species acting in a neuroprotective fashion.
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