Jarvis, B. W. | Search bioRxiv

bioRxiv2026

Neuronal targeted AAV Micro-Dystrophin restores neurobehavioural co-morbidities, grip strength and motor coordination in mdx52 mouse model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a X-linked disorder caused by mutations in the DMD gene, which disrupts production of multiple isoforms of dystrophin in multiple organs namely muscle, heart and brain. While progressive muscle disease and cardiomyopathy are the hallmarks of DMD, over 40% of individuals also experience significant neurobehavioral comorbidities, including autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), obsessive compulsive disorder (OCD) and intellectual disability. These deficits are linked to the loss of brain isoforms and approximately 90% of DMD individuals have loss of either Dp427 or both Dp427 and Dp140 in the brain. We studied the mdx52 mouse model, which lacks these isoforms and exhibits severe fear and anxiety-like behaviours, suitable to evaluate the therapeutic efficacy on neuro-comorbidities after delivering a neuronal-targeted adeno-associated virus (AAV) micro-dystrophin ({micro}Dys) therapy. We compared two delivery routes intravenous (IV) and intracerebroventricular (ICV) in neonatal mdx52 male mice to assess impact on an extensive range of neurobehavioural aspects including emotional reactivity, neurocognitive, OCD and motor coordination deficits. While both routes successfully reduced emotional reactivity and anxiety-related behaviours, IV delivery emerged as the superior therapeutic strategy addressing a more comprehensive spectrum of DMD related brain co-morbidities. Critically, significant improvements in cognitive deficits and OCD-like behaviours were achieved only through IV delivery. This was associated with a widespread lower transduction pattern across the brain, including hindbrain and cerebellum, which were less effectively targeted by ICV injection, although forebrain transduction with ICV delivery was higher. Brain {micro}Dys expression successfully restored dystrophin interactors dystroglycan, syntrophin and pre- and post-synaptic functional interactors VGLUT1, gephyrin, GABAAR with both delivery methods. These results demonstrate that while ICV gene therapy results in improved emotional reactivity and anxiety-related behaviour in the mdx52, only the systemic, neuronal-targeted gene therapy efficiently transduced the central nervous system restoring neuronal synaptic functional complexes of both Dp427 and 140 isoforms and simultaneously restored peripheral NMJ dystrophin deficiency. Beyond cognitive restoration, while both routes improved aspects of gait on CatWalk XT, only IV delivery significantly enhanced motor coordination on the Beam walk and, unexpectedly, normalised grip strength. This was specifically linked to the selective expression of {micro}Dys at neuromuscular junctions (NMJs), which corrected post-synaptic electrophysiological dysfunction of mdx52 mice. Our findings establish a significant foundation for incorporating brain-directed strategies into the future therapeutic approaches for DMD, offering a holistic approach to treating DMD as a multisystemic disease.

neuroscience↗

bioRxiv2023

Human HPSE2 gene transfer ameliorates bladder pathophysiology in a mutant mouse model of urofacial syndrome.

Rare early onset lower urinary tract disorders include defects of functional maturation of the bladder. Current treatments do not target the primary pathobiology of these diseases. Some have a monogenic basis, such as urofacial, or Ochoa, syndrome (UFS). Here, the bladder does not empty fully because of incomplete relaxation of its outflow tract, and subsequent urosepsis can cause kidney failure. UFS is associated with biallelic variants of HPSE2, encoding heparanase-2. This protein is detected in pelvic ganglia, autonomic relay stations that innervate the bladder and control voiding. Bladder outflow tracts of Hpse2 mutant mice display impaired neurogenic relaxation. We hypothesized that HPSE2 gene transfer soon after birth would ameliorate this defect and explored an adeno-associated viral (AAV) vector-based approach. AAV9/HPSE2, carrying human HPSE2 driven by CAG, was administered intravenously into neonatal mice. In the third postnatal week, transgene transduction and expression were sought, and ex vivo myography was undertaken to measure bladder function. In mice administered AAV9/HPSE2, the viral genome was detected in pelvic ganglia. Human HPSE2 was expressed and heparanase-2 became detectable in pelvic ganglia of treated mutant mice. On autopsy, wild-type mice had empty bladders whereas bladders were uniformly distended in mutant mice, a defect ameliorated by AAV9/HPSE2 treatment. Therapeutically, AAV9/HPSE2 significantly ameliorated impaired neurogenic relaxation of Hpse2 mutant bladder outflow tracts. Impaired neurogenic contractility of mutant detrusor smooth muscle was also significantly improved. These results constitute first steps towards curing UFS, a clinically devastating genetic disease featuring a bladder autonomic neuropathy. SummaryIn the first gene therapy for genetic bladder disease, we cured autonomic neurons using AAV-mediated gene delivery in a mouse model of urofacial syndrome.

neuroscience↗