Aggregate-selective antibody attenuates seeded aggregation but not spontaneously evolving disease in SOD1 ALS model mice

Abstract

Increasing evidence suggests that propagation of the motor neuron disease amyotrophic lateral sclerosis (ALS) involves the pathogenic aggregation of disease-associated proteins that spread in a prion-like manner. We have identified two aggregate strains of human superoxide dismutase 1 (hSOD1) that arise in the CNS of transgenic mouse models of SOD1-mediated ALS. Both strains transmit template-directed aggregation and premature fatal paralysis when inoculated into the spinal cord of adult hSOD1 transgenic mice. This spread of pathogenic aggregation could be a potential target for immunotherapeutic intervention. Here we generated mouse monoclonal antibodies (mAbs) directed to exposed epitopes in hSOD1 aggregate strains and identified an aggregate selective mAb that targets the aa 143–153 C-terminal extremity of hSOD1 (αSOD1143–153). Both pre-incubation of seeds with αSOD1143–153 prior to inoculation, and weekly intraperitoneal (i.p.) administration attenuated transmission of pathogenic aggregation and prolonged the survival of seed-inoculated hSOD1G85R Tg mice. In contrast, administration of a mAb targeting aa 65–72 (αSOD165–72), which exhibits high affinity towards monomeric disordered hSOD1, had an adverse effect and aggravated seed induced premature ALS-like disease. Although the mAbs reached similar concentrations in CSF, only αSOD1143–153 was found in association with aggregated hSOD1 in spinal cord homogenates. Our results suggest that an aggregate-selective immunotherapeutic approach may suppress seeded transmission of pathogenic aggregation in ALS. However, long-term administration of αSOD1143–153 was unable to prolong the lifespan of non-inoculated hSOD1G85R Tg mice. Thus, spontaneously initiated hSOD1 aggregation in spinal motor neurons may be poorly accessible to therapeutic antibodies.

Antibody-Based Therapeutic Interventions for Amyotrophic Lateral Sclerosis: A Systematic Literature Review

“…More recently, Lehmann et al investigated the effect of disordered SOD1-selective antibodies on the SOD1 transmission of aggregation properties. In their model, intrathecal inoculation of hSOD1 aggregates isolated from the CNS of ALS mice model exacerbated pathology and SOD1 aggregation in SOD1G85R mice (Lehmann et al, 2020 ). Authors developed two mMAbs specific to epitopes exposed only in aggregated forms of human SOD1 (hSOD1), i.e., a.a. 143-153 of C-terminus of hSOD1 (α-SOD1143-153) and a.a. 65-72 (α-SOD165-72).…”

“…Moreover, α-SOD1143-153 was found in association with aggregated hSOD1 in spinal cord homogenates. However, the administration of antibodies in non-inoculated hSOD1G85R mice did not improve survival nor mitigated spontaneously evolving aggregation, suggesting that the antibody effect is specific to seed-induced ALS-like disease (Lehmann et al, 2020 ).…”

Mutant SOD1 aggregates formed in vitro and in cultured cells are polymorphic and differ from those arising in the CNS

“…For preparation of the strain B seeds used for inoculation, spinal cords from homozygous hSOD1 D90A mice ( n = 3) with early end‐stage paralysis were used (Bergh et al, 2015). Inoculation of strain B seeds into lumbar spinal cord ( n = 5 hSOD1 G85R Tg mice*; n = 5 hSOD1 D90A Tg mice) was performed under deep anesthesia as described previously (Bidhendi et al, 2016; Ekhtiari Bidhendi et al, 2018; Lehmann et al, 2020). All strain B inoculated mice developed a premature ALS‐like paresis and were sacrificed when they reached end‐stage disease symptoms.…”

“…Inoculation of strain B seeds into lumbar spinal cord (n = 5 hSOD1 G85R Tg mice*; n = 5 hSOD1 D90A Tg mice) was performed under deep anesthesia as described previously (Bidhendi et al, 2016;Ekhtiari Bidhendi et al, 2018;Lehmann et al, 2020). All strain B inoculated mice developed a premature ALS-like paresis and were sacrificed when they reached end-stage disease symptoms.…”

“…Cytosolic inclusions containing aggregated SOD1 are hallmarks of ALS, both in patients and in transgenic (Tg) animal models expressing mutant hSOD1 (Kato et al, 2000). Structural characterization using a binary epitope‐mapping (BEM) assay, revealed that two different strains of hSOD1 aggregates can arise in transgenic mice expressing hSOD1 variants (Bergh et al, 2015; Lehmann et al, 2020). One strain, denoted A, was found to form in hSOD1 G93A , hSOD1 G85R , and hSOD1 WT Tg mice, and another strain denoted B, can form in Tg mice expressing hSOD1 D90A .…”