Blocking an epitope of misfolded SOD1 ameliorates disease phenotype in a model of amyotrophic lateral sclerosis

The current strategies to mitigate the toxicity of misfolded superoxide dismutase 1 (SOD1) in familial amyotrophic lateral sclerosis via blocking SOD1 expression in the CNS are indiscriminative for misfolded and intact proteins, and as such, entail a risk of depriving CNS cells of their essential antioxidant potential. As an alternative approach to neutralize misfolded and spare unaffected SOD1 species, we developed scFv-SE21 antibody that blocks the & beta;6/& beta;7 loop epitope exposed exclusively in misfolded SOD1.The & beta;6/& beta;7 loop epitope has previously been proposed to initiate amyloid-like aggregation of misfolded SOD1 and mediate its prion-like activity. The adeno-associated virus-mediated expression of scFv-SE21 in the CNS of hSOD1G37R mice rescued spinal motor neurons, reduced the accumulation of misfolded SOD1, decreased gliosis and thus delayed disease onset and extended survival by 90 days.The results provide evidence for the role of the exposed & beta;6/& beta;7 loop epitope in the mechanism of neurotoxic gain-of-function of misfolded SOD1 and open avenues for the development of mechanism-based anti-SOD1 therapeutics, whose selective targeting of misfolded SOD1 species may entail a reduced risk of collateral oxidative damage to the CNS. Bakavayev et al. generate an antibody targeting the structural element responsible for the neurotoxicity of the ALS pathogenic protein SOD1, and show that the antibody extends survival in SOD1 mutant mice. Selective targeting of pathogenic SOD1 species could preserve intact SOD1 activity essential for normal physiology.

Automated summary

The researchers developed an antibody scFv-SE21 that can target the structural element responsible for the neurotoxicity of misfolded SOD1, and showed that it delays disease onset and extends survival in ALS mice.