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PloS One 2023Duchenne muscular dystrophy (DMD) is caused by genetic mutations leading to lack of dystrophin in skeletal muscle. A better understanding of how objective biomarkers for...
Duchenne muscular dystrophy (DMD) is caused by genetic mutations leading to lack of dystrophin in skeletal muscle. A better understanding of how objective biomarkers for DMD vary across subjects and over time is needed to model disease progression and response to therapy more effectively, both in pre-clinical and clinical research. We present an in-depth characterization of disease progression in 3 murine models of DMD by multiomic analysis of longitudinal trajectories between 6 and 30 weeks of age. Integration of RNA-seq, mass spectrometry-based metabolomic and lipidomic data obtained in muscle and blood samples by Multi-Omics Factor Analysis (MOFA) led to the identification of 8 latent factors that explained 78.8% of the variance in the multiomic dataset. Latent factors could discriminate dystrophic and healthy mice, as well as different time-points. MOFA enabled to connect the gene expression signature in dystrophic muscles, characterized by pro-fibrotic and energy metabolism alterations, to inflammation and lipid signatures in blood. Our results show that omic observations in blood can be directly related to skeletal muscle pathology in dystrophic muscle.
Topics: Mice; Animals; Dystrophin; Mice, Inbred mdx; Multiomics; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Disease Progression; Disease Models, Animal
PubMed: 37000843
DOI: 10.1371/journal.pone.0283869 -
Neuromuscular Disorders : NMD Jan 2023Accelerated approval based on a likely surrogate endpoint can be life-changing for patients suffering from a rare progressive disease with unmet medical need, as it... (Review)
Review
Accelerated approval based on a likely surrogate endpoint can be life-changing for patients suffering from a rare progressive disease with unmet medical need, as it substantially hastens access to potentially lifesaving therapies. In one such example, antisense morpholinos were approved to treat Duchenne muscular dystrophy (DMD) based on measurement of shortened dystrophin in skeletal muscle biopsies as a surrogate biomarker. New, promising therapeutics for DMD include AAV gene therapy to restore another form of dystrophin termed mini- or microdystrophin. AAV-microdystrophins are currently in clinical trials but have yet to be accepted by regulatory agencies as reasonably likely surrogate endpoints. To evaluate microdystrophin expression as a reasonably likely surrogate endpoint for DMD, this review highlights dystrophin biology in the context of functional and clinical benefit to support the argument that microdystrophin proteins have a high probability of providing clinical benefit based on their rational design. Unlike exon-skipping based strategies, the approach of rational design allows for functional capabilities (i.e. quality) of the protein to be maximized with every patient receiving the same optimized microdystrophin. Therefore, the presence of rationally designed microdystrophin in a muscle biopsy is likely to predict clinical benefit and is consequently a strong candidate for a surrogate endpoint analysis to support accelerated approval.
Topics: Humans; Dystrophin; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Genetic Therapy; Biomarkers
PubMed: 36575103
DOI: 10.1016/j.nmd.2022.12.007 -
Science Translational Medicine Jan 2023Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease caused by the absence of dystrophin, a membrane-stabilizing protein encoded by the gene....
Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease caused by the absence of dystrophin, a membrane-stabilizing protein encoded by the gene. Although mouse models of DMD provide insight into the potential of a corrective therapy, data from genetically homologous large animals, such as the dystrophin-deficient golden retriever muscular dystrophy (GRMD) model, may more readily translate to humans. To evaluate the clinical translatability of an adeno-associated virus serotype 9 vector (AAV9)-microdystrophin (μDys5) construct, we performed a blinded, placebo-controlled study in which 12 GRMD dogs were divided among four dose groups [control, 1 × 10 vector genomes per kilogram (vg/kg), 1 × 10 vg/kg, and 2 × 10 vg/kg; = 3 each], treated intravenously at 3 months of age with a canine codon-optimized microdystrophin construct, rAAV9-CK8e-c-μDys5, and followed for 90 days after dosing. All dogs received prednisone (1 milligram/kilogram) for a total of 5 weeks from day -7 through day 28. We observed dose-dependent increases in tissue vector genome copy numbers; μDys5 protein in multiple appendicular muscles, the diaphragm, and heart; limb and respiratory muscle functional improvement; and reduction of histopathologic lesions. As expected, given that a truncated dystrophin protein was generated, phenotypic test results and histopathologic lesions did not fully normalize. All administrations were well tolerated, and adverse events were not seen. These data suggest that systemically administered AAV-microdystrophin may be dosed safely and could provide therapeutic benefit for patients with DMD.
Topics: Animals; Dogs; Humans; Infant, Newborn; Mice; Dystrophin; Genetic Therapy; Heart; Muscle, Skeletal; Muscles; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne
PubMed: 36599002
DOI: 10.1126/scitranslmed.abo1815 -
Hellenic Journal of Cardiology : HJC =... 2023Duchenne muscular dystrophy is a fatal X-linked recessive disease affecting approximately 1 in 3500 births. It is characterized by a genetic lack of dystrophin, which is... (Review)
Review
Duchenne muscular dystrophy is a fatal X-linked recessive disease affecting approximately 1 in 3500 births. It is characterized by a genetic lack of dystrophin, which is an essential protein for maintaining muscle integrity. The lack of dystrophin plays a pathophysiological role in the development of dilated cardiomyopathy in Duchenne muscular dystrophy. Currently, no consensus exists on specific pharmacological therapy guidelines for these patients; however, it centers around the guidelines for heart failure management. This systematic review investigated 12 randomized control trials dating back to 2005 in the pharmacotherapy of patients with dilated cardiomyopathy Duchenne muscular dystrophy. This review specifically included angiotensin-converting enzyme inhibitors, aldosterone receptor blockers, angiotensin receptor/neprilysin inhibitors, beta-blockers, and mineralocorticoid receptor antagonists. Despite their limitations, these studies have shown promising effects in improving the overall heart function and prognosis in patients with this condition. However, to attain higher statistical significance, future studies should investigate larger populations and for longer periods.
Topics: Humans; Cardiomyopathy, Dilated; Muscular Dystrophy, Duchenne; Dystrophin; Angiotensin-Converting Enzyme Inhibitors; Adrenergic beta-Antagonists
PubMed: 37406964
DOI: 10.1016/j.hjc.2023.06.007 -
Neurotherapeutics : the Journal of the... Oct 2018Duchenne muscular dystrophy (DMD) is a progressive X-linked degenerative muscle disease due to mutations in the DMD gene. Genetic confirmation has become standard in... (Review)
Review
Duchenne muscular dystrophy (DMD) is a progressive X-linked degenerative muscle disease due to mutations in the DMD gene. Genetic confirmation has become standard in recent years. Improvements in the standard of care for DMD have led to improved survival. Novel treatments for DMD have focused on reducing the dystrophic mechanism of the muscle disease, modulating utrophin protein expression, and restoring dystrophin protein expression. Among the strategies to reduce the dystrophic mechanisms are 1) inhibiting inflammation, 2) promoting muscle growth and regeneration, 3) reducing fibrosis, and 4) facilitating mitochondrial function. The agents under investigation include a novel steroid, myostatin inhibitors, idebenone, an anti-CTGF antibody, a histone deacetylase inhibitor, and cardiosphere-derived cells. For utrophin modulation, AAV-mediated gene therapy with GALGT2 is currently being investigated to upregulate utrophin expression. Finally, the strategies for dystrophin protein restoration include 1) nonsense readthrough, 2) synthetic antisense oligonucleotides for exon skipping, and 3) AAV-mediated micro/minidystrophin gene delivery. With newer agents, we are witnessing the use of more advanced biotechnological methods. Although these potential breakthroughs provide significant promise, they may also raise new questions regarding treatment effect and safety.
Topics: Animals; Dystrophin; Humans; Muscular Dystrophy, Duchenne
PubMed: 30414046
DOI: 10.1007/s13311-018-00687-z -
The AAPS Journal Dec 2022Duchenne muscular dystrophy (DMD) is a degenerative muscular disease affecting roughly one in 5000 males at birth. The disease is often caused by inherited X-linked...
Duchenne muscular dystrophy (DMD) is a degenerative muscular disease affecting roughly one in 5000 males at birth. The disease is often caused by inherited X-linked recessive pathogenic variants in the dystrophin gene, but may also arise from de novo mutations. Disease-causing variants include nonsense, out of frame deletions or duplications that result in loss of dystrophin protein expression. There is currently no cure for DMD and the few treatment options available aim at slowing muscle degradation. New advances in gene therapy and understanding of dystrophin (DYS) expression in other muscular dystrophies have opened new opportunities for treatment. Therefore, reliable methods are needed to monitor dystrophin expression and assess the efficacy of new therapies for muscular dystrophies such as DMD and Becker muscular dystrophy (BMD). Here, we describe the validation of a novel Western blot (WB) method for the quantitation of mini-dystrophin protein in human skeletal muscle tissues that is easy to adopt in most laboratory settings. This WB method was assessed through precision, accuracy, selectivity, dilution linearity, stability, and repeatability. Based on mini-DYS standard performance, the assay has a dynamic range of 0.5-15 ng protein (per 5 µg total protein per lane), precision of 3.3 to 25.5%, and accuracy of - 7.5 to 3.3%. Our stability assessment showed that the protein is stable after 4 F/T cycles, up to 2 h at RT and after 7 months at - 70°C. Furthermore, our WB method was compared to the results from our recently published LC-MS method. Workflow for our quantitative WB method to determine mini-dystrophin levels in muscle tissues (created in Biorender.com). Step 1 involves protein extraction from skeletal muscle tissue lysates from control, DMD, or BMD biospecimen. Step 2 measures total protein concentrations. Step 3 involves running gel electrophoresis with wild-type dystrophin (wt-DYS) from muscle tissue extracts alongside mini-dystrophin STD curve and mini-DYS and protein normalization with housekeeping GAPDH.
Topics: Male; Infant, Newborn; Humans; Dystrophin; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Biopsy; Blotting, Western
PubMed: 36539515
DOI: 10.1208/s12248-022-00776-0 -
Proceedings of the National Academy of... Jul 2023Duchenne muscular dystrophy (DMD) is a fatal X-linked disease caused by mutations in the gene, leading to complete absence of dystrophin and progressive degeneration of...
Duchenne muscular dystrophy (DMD) is a fatal X-linked disease caused by mutations in the gene, leading to complete absence of dystrophin and progressive degeneration of skeletal musculature and myocardium. In DMD patients and in a corresponding pig model with a deletion of exon 52 (Δ52), expression of an internally shortened dystrophin can be achieved by skipping of exon 51 to reframe the transcript. To predict the best possible outcome of this strategy, we generated Δ51-52 pigs, additionally representing a model for Becker muscular dystrophy (BMD). Δ51-52 skeletal muscle and myocardium samples stained positive for dystrophin and did not show the characteristic dystrophic alterations observed in Δ52 pigs. Western blot analysis confirmed the presence of dystrophin in the skeletal muscle and myocardium of Δ51-52 pigs and its absence in Δ52 pigs. The proteome profile of skeletal muscle, which showed a large number of abundance alterations in Δ52 vs. wild-type (WT) samples, was normalized in Δ51-52 samples. Cardiac function at age 3.5 mo was significantly reduced in Δ52 pigs (mean left ventricular ejection fraction 58.8% vs. 70.3% in WT) but completely rescued in Δ51-52 pigs (72.3%), in line with normalization of the myocardial proteome profile. Our findings indicate that ubiquitous deletion of exon 51 in Δ52 pigs largely rescues the rapidly progressing, severe muscular dystrophy and the reduced cardiac function of this model. Long-term follow-up studies of Δ51-52 pigs will show if they develop symptoms of the milder BMD.
Topics: Animals; Swine; Muscular Dystrophy, Duchenne; Dystrophin; Proteome; Stroke Volume; Ventricular Function, Left; Muscle, Skeletal; Exons
PubMed: 37428903
DOI: 10.1073/pnas.2301250120 -
International Journal of Molecular... Oct 2018Mutations in the gene encoding for the intracellular protein dystrophin cause severe forms of muscular dystrophy. These so-called dystrophinopathies are characterized by... (Review)
Review
Mutations in the gene encoding for the intracellular protein dystrophin cause severe forms of muscular dystrophy. These so-called dystrophinopathies are characterized by skeletal muscle weakness and degeneration. Dystrophin deficiency also gives rise to considerable complications in the heart, including cardiomyopathy development and arrhythmias. The current understanding of the pathomechanisms in the dystrophic heart is limited, but there is growing evidence that dysfunctional voltage-dependent ion channels in dystrophin-deficient cardiomyocytes play a significant role. Herein, we summarize the current knowledge about abnormalities in voltage-dependent sarcolemmal ion channel properties in the dystrophic heart, and discuss the potentially underlying mechanisms, as well as their pathophysiological relevance.
Topics: Animals; Arrhythmias, Cardiac; Cardiomyopathies; Dystrophin; Humans; Ion Channels; Potassium Channels; Sarcolemma; Sodium Channels
PubMed: 30360568
DOI: 10.3390/ijms19113296 -
The Journal of Clinical Investigation Jun 2020Muscular dystrophies are debilitating disorders that result in progressive weakness and degeneration of skeletal muscle. Although the genetic mutations and clinical... (Review)
Review
Muscular dystrophies are debilitating disorders that result in progressive weakness and degeneration of skeletal muscle. Although the genetic mutations and clinical abnormalities of a variety of neuromuscular diseases are well known, no curative therapies have been developed to date. The advent of genome editing technology provides new opportunities to correct the underlying mutations responsible for many monogenic neuromuscular diseases. For example, Duchenne muscular dystrophy, which is caused by mutations in the dystrophin gene, has been successfully corrected in mice, dogs, and human cells through CRISPR/Cas9 editing. In this Review, we focus on the potential for, and challenges of, correcting muscular dystrophies by editing disease-causing mutations at the genomic level. Ideally, because muscle tissues are extremely long-lived, CRISPR technology could offer a one-time treatment for muscular dystrophies by correcting the culprit genomic mutations and enabling normal expression of the repaired gene.
Topics: Animals; CRISPR-Cas Systems; Dystrophin; Gene Editing; Humans; Muscular Dystrophy, Duchenne; Mutation
PubMed: 32478678
DOI: 10.1172/JCI136873 -
Neuromuscular Disorders : NMD Mar 2024Duchenne muscular dystrophy (DMD) is a devastating muscle disease caused by the absence of functional dystrophin. There are multiple ongoing clinical trials for DMD that...
Duchenne muscular dystrophy (DMD) is a devastating muscle disease caused by the absence of functional dystrophin. There are multiple ongoing clinical trials for DMD that are testing gene therapy treatments consisting of adeno-associated viral (AAV) vectors carrying miniaturized versions of dystrophin optimized for function, termed micro-dystrophins (μDys). Utrophin, the fetal homolog of dystrophin, has repeatedly been reported to be upregulated in human DMD muscle as a compensatory mechanism, but whether µDys displaces full-length utrophin is unknown. In this study, dystrophin/utrophin-deficient mice with transgenic overexpression of full-length utrophin in skeletal muscles were systemically administered low doses of either AAV6-CK8e-Hinge3-µDys (μDysH3) or AAV6-CK8e-μDys5 (μDys5). We used immunofluorescence to qualitatively assess the localization of μDys with transgenic utrophin and neuronal nitric oxide synthase (nNOS) in quadriceps muscles. μDys protein resulting from both gene therapies co-localized at myofiber membranes with transgenic utrophin. We also confirmed the sarcolemmal co-localization of nNOS with μDys5, but not with transgenic utrophin expression or μDysH3. Transgenic utrophin expression and μDys proteins produced from both therapies stabilize the dystrophin-glycoprotein complex as observed by sarcolemmal localization of β-dystroglycan. This study suggests that µDys gene therapy will likely not inhibit any endogenous compensation by utrophin in DMD muscle.
Topics: Animals; Humans; Mice; Dystrophin; Utrophin; Muscle Fibers, Skeletal; Muscle, Skeletal; Genetic Therapy
PubMed: 38301403
DOI: 10.1016/j.nmd.2024.01.004