Rescue of spinal cord pathology by peripherally administered AR-targeted ASO in symptomatic AR113Q mice

Degeneration of the neuromuscular system is a characteristic feature of spinal and bulbar muscular atrophy (SBMA), a CAG/polyglutamine (polyQ) expansion disorder caused by mutation in the androgen receptor (AR). Using a gene targeted mouse model of SBMA, AR113Q mice, we demonstrate age-dependent degeneration of the neuromuscular system that initially manifests with muscle weakness and atrophy and progresses to include denervation of neuromuscular junctions and lower motor neuron soma atrophy. Using this model, we tested the hypothesis that therapeutic intervention targeting skeletal muscle during this period of disease progression arrests degeneration of the neuromuscular system. To accomplish this, AR-targeted antisense oligonucleotides were administered subcutaneously to symptomatic AR113Q mice to reduce expression of polyQ AR in peripheral tissues but not in the spinal cord. This intervention rescued muscle atrophy, neuromuscular junction innervation, lower motor neuron soma size, and survival in aged AR113Q mice. Single-nucleus RNA sequencing revealed age-dependent transcriptional changes in the AR113Q spinal cord during disease progression which were mitigated by peripheral AR gene silencing. Our findings underscore the intricate interplay between peripheral tissues and the central nervous system in SBMA and emphasize the therapeutic effectiveness of peripheral gene knockdown in symptomatic disease. Overall design: Bulk RNA-seq data from lumbar spinal cord extracted from wild-type C57BL6/J male mice, aged to 52 weeks old, having received once weekly subcutaneous injection of AR-targeting or non-targeting (NT) ASO at 25 mg/kg in sterile PBS starting at 26 weeks of age. N = 6 mice for AR-ASO, 5 mice for NT-ASO.