Dataset Information

Microdystrophin ameliorates muscular dystrophy in the canine model of duchenne muscular dystrophy.

ABSTRACT: Dystrophin deficiency results in lethal Duchenne muscular dystrophy (DMD). Substituting missing dystrophin with abbreviated microdystrophin has dramatically alleviated disease in mouse DMD models. Unfortunately, translation of microdystrophin therapy has been unsuccessful in dystrophic dogs, the only large mammalian model. Approximately 70% of the dystrophin-coding sequence is removed in microdystrophin. Intriguingly, loss of ?50% dystrophin frequently results in severe disease in patients. To test whether the small gene size constitutes a fundamental design error for large mammalian muscle, we performed a comprehensive study using 22 dogs (8 normal and 14 dystrophic). We delivered the ?R2-15/?R18-19/?R20-23/?C microdystrophin gene to eight extensor carpi ulnaris (ECU) muscles in six dystrophic dogs using Y713F tyrosine mutant adeno-associated virus (AAV)-9 (2.6 × 10(13) viral genome (vg) particles/muscle). Robust expression was observed 2 months later despite T-cell infiltration. Major components of the dystrophin-associated glycoprotein complex (DGC) were restored by microdystrophin. Treated muscle showed less inflammation, fibrosis, and calcification. Importantly, therapy significantly preserved muscle force under the stress of repeated cycles of eccentric contraction. Our results have established the proof-of-concept for microdystrophin therapy in dystrophic muscles of large mammals and set the stage for clinical trial in human patients.

SUBMITTER: Shin JH

PROVIDER: S-EPMC3616540 | biostudies-other | 2013 Apr

REPOSITORIES: biostudies-other

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Microdystrophin ameliorates muscular dystrophy in the canine model of duchenne muscular dystrophy.

Shin Jin-Hong JH Pan Xiufang X Hakim Chady H CH Yang Hsiao T HT Yue Yongping Y Zhang Keqing K Terjung Ronald L RL Duan Dongsheng D

Molecular therapy : the journal of the American Society of Gene Therapy 20130115 4

Dystrophin deficiency results in lethal Duchenne muscular dystrophy (DMD). Substituting missing dystrophin with abbreviated microdystrophin has dramatically alleviated disease in mouse DMD models. Unfortunately, translation of microdystrophin therapy has been unsuccessful in dystrophic dogs, the only large mammalian model. Approximately 70% of the dystrophin-coding sequence is removed in microdystrophin. Intriguingly, loss of ≥50% dystrophin frequently results in severe disease in patients. To t ...[more]

PMID: 23319056

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Project description:Duchenne muscular dystrophy (DMD) causes progressive disability in 1 of every 5,000 boys due to the lack of functional dystrophin protein. Despite much advancement in knowledge about DMD disease presentation and progression-attributable in part to studies using mouse and canine models of the disease-current DMD treatments are not equally effective in all patients. There remains, therefore, a need for translational animal models in which novel treatment targets can be identified and evaluated. Golden Retriever muscular dystrophy (GRMD) is a phenotypically and genetically homologous animal model of DMD. As with DMD, speed of disease progression in GRMD varies substantially. However, unlike DMD, all GRMD dogs possess the same causal mutation; therefore genetic modifiers of phenotypic variation are relatively easier to identify. Furthermore, the GRMD dogs used in this study reside within the same colony, reducing the confounding effects of environment on phenotypic variation. To detect modifiers of disease progression, we developed gene expression profiles using RNA sequencing for 9 dogs: 6 GRMD dogs (3 with faster-progressing and 3 with slower-progressing disease, based on quantitative, objective biomarkers) and 3 control dogs from the same colony. All dogs were evaluated at 2 time points: early disease onset (3 months of age) and the point at which GRMD stabilizes (6 months of age) using quantitative, objective biomarkers identified as robust against the effects of relatedness/inbreeding. Across all comparisons, the most differentially expressed genes fell into 3 categories: myogenesis/muscle regeneration, metabolism, and inflammation. Our findings are largely in concordance with DMD and mouse model studies, reinforcing the utility of GRMD as a translational model. Novel findings include the strong up-regulation of chitinase 3-like 1 (CHI3L1) in faster-progressing GRMD dogs, suggesting previously unexplored mechanisms underlie progression speed in GRMD and DMD. In summary, our findings support the utility of RNA sequencing for evaluating potential biomarkers of GRMD progression speed, and are valuable for identifying new avenues of exploration in DMD research.

Project description:Duchenne muscular dystrophy (DMD) is the most common inherited muscle disorder that causes severe disability and death of young men. This disease is characterized by progressive muscle degeneration aggravated by sterile inflammation and is also associated with cognitive impairment and low bone density. Given that no current treatment can improve the long-term outcome, approaches with a strong translational potential are urgently needed. Duchenne muscular dystrophy (DMD) alters P2RX7 signaling in both muscle and inflammatory cells and inhibition of this receptor resulted in a significant attenuation of muscle and non-muscle symptoms in DMDmdx mouse model. As P2RX7 is an attractive target in a range of human diseases, specific antagonists have been developed. Yet, these will require lengthy safety testing in the pediatric population of Duchenne muscular dystrophy (DMD) patients. In contrast, Nucleoside Reverse Transcriptase Inhibitors (NRTIs) can act as P2RX7 antagonists and are drugs with an established safety record, including in children. We demonstrate here that AZT (Zidovudine) inhibits P2RX7 functions acting via the same allosteric site as other antagonists. Moreover, short-term AZT treatment at the peak of disease in DMDmdx mice attenuated the phenotype without any detectable side effects. Recovery was evident in the key parameters such as reduced sarcolemma permeability confirmed by lower serum creatine kinase levels and IgG influx into myofibres, decreased inflammatory cell numbers and inflammation markers in leg and heart muscles of treated mice. Moreover, this short-term therapy had some positive impact on muscle strength in vivo and no detrimental effect on mitochondria, which is the main side-effect of Nucleoside Reverse Transcriptase Inhibitors (NRTIs). Given these results, we postulate that AZT could be quickly re-purposed for the treatment of this highly debilitating and lethal disease. This approach is not constrained by causative DMD mutations and may be effective in alleviating both muscle and non-muscle abnormalities.

Dataset Information

Microdystrophin ameliorates muscular dystrophy in the canine model of duchenne muscular dystrophy.

Publications

Microdystrophin ameliorates muscular dystrophy in the canine model of duchenne muscular dystrophy.

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