Duchenne and Becker muscular dystrophies (DMD/BMD) are X-linked recessive genetic disorders caused by mutations in the dystrophin gene. DMD is among the most common lethal inherited disorder of children, but finding a cure remains an elusive goal. Improved treatment approaches using surgery, corticosteroids, respiratory support and heart medication are leading to increases in lifespan. While most patients previously died of respiratory failure due to weakness of the diaphragm and intercostal muscles, a shift has been observed to an increasingly older patient population dying of respiratory or heart failure. Nonetheless, most treatment strategies for DMD/BMD are focused on limb muscles, despite evidence that skeletal muscle rescue can exacerbate cardiac dysfunction. Our lab has shown that adeno-associated viral (AAV) vectors can efficiently target both skeletal and cardiac muscles in mouse (mdx) and canine models for DMD, and that systemic AAV delivery of micro-dystrophin cassettes can halt progressive dystrophic changes and significantly improve diaphragm and cardiac function in mdx mice. Functional rescue, while impressive, is incomplete and recent studies suggest multiple ways to improve the functionality and muscle-specific expression of micro-dystrophin. Testing and comparing these modified micro-dystrophins is complicated by the mildness of the mdx mouse phenotype, so we propose to use a more severely affected mdx4cv/Dba-2 mutant that displays extensive cardiorespiratory fibrosis and a more progressive pathology. These cassettes will comprise both new microdystrophin cDNAs and new gene regulatory cassettes optimized for expression and function in respiratory and cardiac muscle following systemic AAV-mediated gene transfer to adult animals. We will also integrate these delivery systems in the context of strategies designed to prevent immune-mediated loss of dystrophin expression. These include a novel reverse vaccine protocol designed to induce tolerance, and transient immune suppression. Together these approaches could significantly impact the ability to treat respiratory and cardiac muscles of DMD patients. This work also has broad implications for gene therapy of other disorders involving cardiopulmonary dysfunction.

Public Health Relevance

Mutations that affect production of the protein dystrophin are the cause of Duchenne muscular dystrophy, the most common lethal inherited disorder of children. This project is focused on methods to improve the ability to replace dystrophin in breathing muscles and the heart, which account for most deaths. The results will be important in guiding the development of therapies for the dystrophies.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Kaltman, Jonathan R
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University of Washington
Schools of Medicine
United States
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Ho, Peggy P; Lahey, Lauren J; Mourkioti, Foteini et al. (2018) Engineered DNA plasmid reduces immunity to dystrophin while improving muscle force in a model of gene therapy of Duchenne dystrophy. Proc Natl Acad Sci U S A 115:E9182-E9191
Halbert, Christine L; Allen, James M; Chamberlain, Jeffrey S (2018) AAV6 Vector Production and Purification for Muscle Gene Therapy. Methods Mol Biol 1687:257-266
Bengtsson, Niclas E; Hall, John K; Odom, Guy L et al. (2017) Corrigendum: Muscle-specific CRISPR/Cas9 dystrophin gene editing ameliorates pathophysiology in a mouse model for Duchenne muscular dystrophy. Nat Commun 8:16007
Chamberlain, Joel R; Chamberlain, Jeffrey S (2017) Progress toward Gene Therapy for Duchenne Muscular Dystrophy. Mol Ther 25:1125-1131
Hakim, Chady H; Wasala, Nalinda B; Pan, Xiufang et al. (2017) A Five-Repeat Micro-Dystrophin Gene Ameliorated Dystrophic Phenotype in the Severe DBA/2J-mdx Model of Duchenne Muscular Dystrophy. Mol Ther Methods Clin Dev 6:216-230
Thomson, Kassandra S; Odom, Guy L; Murry, Charles E et al. (2016) Translation of Cardiac Myosin Activation with 2-deoxy-ATP to Treat Heart Failure via an Experimental Ribonucleotide Reductase-Based Gene Therapy. JACC Basic Transl Sci 1:666-679
Whitehead, Nicholas P; Bible, Kenneth L; Kim, Min Jeong et al. (2016) Validation of ultrasonography for non-invasive assessment of diaphragm function in muscular dystrophy. J Physiol 594:7215-7227
Kolwicz Jr, Stephen C; Odom, Guy L; Nowakowski, Sarah G et al. (2016) AAV6-mediated Cardiac-specific Overexpression of Ribonucleotide Reductase Enhances Myocardial Contractility. Mol Ther 24:240-250