Hydroethanolic Soy Extract Rich in Isoflavones Protects Dystrophic Mutant Mice From Oxidative Stress and Inflammation via the ROS/NF-κB Feedback Pathway.

Physiological Characterization of Muscle Strength With Variable Levels of Dystrophin Restoration in mdx Mice Following Local Antisense Therapy

Murine models of Duchenne muscular dystrophy: is there a best model?

CRISPR/Cas9-Mediated Genome Editing Corrects Dystrophin Mutation in Skeletal Muscle Stem Cells in a Mouse Model of Muscle Dystrophy.

Functional Rescue of Dystrophin-deficient mdx Mice by a Chimeric Peptide-PMO

Patients with Duchenne muscular dystrophy (DMD) have reduced muscle function due to chronic muscle damage, inflammation, oxidative stress, and reduced oxidative capacity. Resveratrol reduces inflammation and oxidative stress, and increases oxidative capacity in other disease models. The purpose of this study was to determine the effects of resveratrol on muscle function, muscle pathology, and oxidative capacity in young mdx mice. For this, 4- to 5-week-old male mdx mice were randomized into control or resveratrol-treated groups and given resveratrol (100 mg/kg body mass) or an equal volume of water by gavage every other day for 8 weeks. Muscle function was assessed pre- and post-treatment. Central nucleation, total immune cell infiltrate, oxidative stress, and oxidative capacity were measured post-treatment. Resveratrol mediated substantial improvements in rotarod performance and in-situ peak tension by 53% and 17%, respectively, and slight improvements in central nucleation and oxidative stress. Resveratrol did not affect total immune cell infiltrate at 12 weeks of age, and had no effect on oxidative capacity. Resveratrol improves muscle function in mdx mice despite small changes in muscle pathology. The likely mechanism is a resveratrol-mediated reduction in immune cell infiltrate at the early stages of this disease, as previously reported by our laboratory.

Transduction of Full-length Dystrophin to Multiple Skeletal Muscles Improves Motor Performance and Life Span in Utrophin/Dystrophin Double Knockout Mice

Gene-mediated Restoration of Normal Myofiber Elasticity in Dystrophic Muscles

IL-6 Blockade as a Therapeutic Approach for Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a genetic disease caused by defects in the dystrophin gene. Patients have severe progressive respiratory muscle dysfunction due to progressive weakness and fibrosis culminating in hypoxaemic periods due to hypoventilation. We examined respiratory function in young adult male Mdx (dystrophin deficient) mice (C57BL/10ScSnMdx/J, n=11) and wild type (WT) controls (C57BL/10ScSn, n=10). During normoxic breathing, Mdx mice had significantly reduced breathing frequency, tidal volume and minute ventilation compared to WT. Mdx mice had a significantly increased ventilatory response to acute hypoxic challenge. We also determined that young adult Mdx mice have reduced diaphragm functional capacity compared to WT, with significant decreases in tetanic force, work and power. Interestingly, Mdx diaphragm displayed tolerance to an acute (6hr) in vivo hypoxic stress, which was not observed in WT. In separate studies, co‐treatment with a monoclonal IL‐6 receptor antibody (MR1‐61; 0.3mg/kg) and the CRFR2 agonist, Urocortin 2 (30µg/kg) both administered by 6 subcutaneous injections over 2 weeks completely rescued Mdx diaphragm muscle force loss compared to saline treatment. Mdx mice have pronounced respiratory muscle dysfunction and impaired normoxic ventilation suggestive of hypoventilation. Enhanced hypoxic chemosensitivity and respiratory muscle tolerance of hypoxic stress are suggestive of adaptation to chronic hypoxaemia in young adult life. Hypoxia, stress and immune factors are implicated in diaphragm dysfunction in the Mdx mouse model of DMD.The MR1‐61 antibody was gifted by Chugai Pharmaceuticals, Tokyo, Japan.

Duchenne muscular dystrophy (DMD), caused by absence of the protein dystrophin, is a common, degenerative muscle disease affecting 1:5000 males worldwide. With recent advances in respiratory care, cardiac dysfunction now accounts for 50% of mortality in DMD. Recently, we demonstrated that simvastatin substantially improved skeletal muscle health and function in mdx (DMD) mice. Given the known cardiovascular benefits ascribed to statins, the aim of this study was to evaluate the efficacy of simvastatin on cardiac function in mdx mice. Remarkably, in 12‐month old mdx mice, simvastatin reversed diastolic dysfunction to normal after short‐term treatment (8 weeks), as measured by echocardiography in animals anesthetized with isoflurane and administered dobutamine to maintain a physiological heart rate. This improvement in diastolic function was accompanied by increased phospholamban phosphorylation in simvastatin‐treated mice. Echocardiography measurements during long‐term treatment, from 6 months up to 18 months of age, showed that simvastatin significantly improved in vivo cardiac function compared to untreated mdx mice, and prevented fibrosis in these very old animals. Cardiac dysfunction in DMD is also characterized by decreased heart rate variability (HRV), which indicates autonomic function dysregulation. Therefore, we measured cardiac ECG and demonstrated that short‐term simvastatin treatment significantly increased heart rate variability (HRV) in 14‐month‐old conscious mdx mice, which was reversed by atropine. This finding suggests that enhanced parasympathetic function is likely responsible for the improved HRV mediated by simvastatin. Together, these findings indicate that simvastatin markedly improves cardiac health and function in dystrophic mice, and therefore may provide a novel approach for treating cardiomyopathy in DMD.

Glycine Enhances Satellite Cell Proliferation, Cell Transplantation, and Oligonucleotide Efficacy in Dystrophic Muscle.

Duchenne muscular dystrophy (DMD) is the most common inherited muscular dystrophy. Patients experience DMD in their 20s from cardiac or respiratory failure related to progressive muscle wasting. Currently, the only treatments for the symptoms of DMD are available. Muscle fibrosis, a DMD feature, leads to reduced muscle function and muscle mass, and hampers pharmaceutical therapeutic efficacy. Although antifibrotic agents may be useful, none is currently approved. Phosphodiesterase 4 (PDE4) inhibitors have exhibited antifibrotic effects in human and animal models. In this study, we showed beneficial effects of the PDE4 inhibitor piclamilast in the DMD mdx mouse. Piclamilast reduced the mRNA level of profibrotic genes, including collagen 1A1, in the gastrocnemius and diaphragm, in the mdx mouse, and significantly reduced the Sirius red staining area. The PDE5 inhibitors sildenafil and tadalafil ameliorated functional muscle ischemia in boys with DMD, and sildenafil reversed cardiac dysfunction in the mdx mouse. Single-treatment piclamilast or sildenafil showed similar antifibrotic effects on the gastrocnemius; combination therapy showed a potent antifibrotic effect, and piclamilast and combination therapy increased peroxisome proliferator-activated receptor γ coactivator-1α mRNA in mouse gastrocnemius. In summary, we confirmed that piclamilast has significant antifibrotic effects in mdx mouse muscle and is a potential treatment for muscle fibrosis in DMD.-Nio, Y., Tanaka, M., Hirozane, Y., Muraki, Y., Okawara, M., Hazama, M., Matsuo, T. Phosphodiesterase 4 inhibitor and phosphodiesterase 5 inhibitor combination therapy has antifibrotic and anti-inflammatory effects in mdx mice with Duchenne muscular dystrophy.

Imaging with time-of-flight secondary ion mass spectrometry (TOF-SIMS) has expanded very rapidly with the development of gold cluster ion sources (Au(3+)). It is now possible to acquire ion density maps (ion images) on a tissue section without any treatment and with a lateral resolution of few micrometers. In this article, we have taken advantage of this technique to study the degeneration/regeneration process in muscles of a Duchenne muscular dystrophy model mouse. Specific distribution of different lipid classes (fatty acids, triglycerides, phospholipids, tocopherol, coenzyme Q9, and cholesterol) allows us to distinguish three different regions on a mouse leg section: one is destroyed, another is degenerating (oxidative stress and deregulation of the phosphoinositol cycle), and the last one is stable. TOF-SIMS imaging shows the ability to localize directly on a tissue section a great number of lipid compounds that reflect the state of the cellular metabolism.

AMPK Activation Stimulates Autophagy and Ameliorates Muscular Dystrophy in the mdx Mouse Diaphragm

Duchenne muscular dystrophy (DMD) is a fatal muscle wasting disease associated with increased inflammation and oxidative stress. The antioxidant N-acetylcysteine (NAC) has been proposed as a therapeutic intervention for DMD boys, but potential adverse effects of NAC have not been widely investigated. We used young (6weeks old) growing mdx mice to investigate the capacity of NAC supplementation (2% in drinking water for 6weeks) to improve dystrophic muscle function and to explore broader systemic effects of NAC treatment. NAC treatment improved normalised measures of muscle function, and decreased inflammation and oxidative stress, but significantly reduced body weight gain, muscle weight and liver weight. Unexpected significant adverse effects of NAC on body and muscle weights indicate that interpretation of muscle function based on normalised force measures should be made with caution and careful consideration is needed when proposing the use of NAC as a therapeutic treatment for young DMD boys. Duchenne muscular dystrophy (DMD) is a fatal X-linked muscle wasting disease characterised by severe muscle weakness, necrosis, inflammation and oxidative stress. The antioxidant N-acetylcysteine (NAC) has been proposed as a potential therapeutic intervention for DMD boys. We investigated the capacity of NAC to improve dystrophic muscle function in the mdx mouse model of DMD. Young (6weeks old) mdx and non-dystrophic C57 mice receiving 2% NAC in drinking water for 6weeks were compared with untreated mice. Grip strength and body weight were measured weekly, before the 12week old mice were anaesthetised and extensor digitorum longus (EDL) muscles were excised for functional analysis and tissues were sampled for biochemical analyses. Compared to untreated mice, the mean (SD) normalised grip strength was significantly greater in NAC-treated mdx [3.13 (0.58) vs 4.87 (0.78)gbody weight (bw)-1 ; P<0.001] and C57 mice [3.90 (0.32) vs 5.32 (0.60)gbw-1 ; P<0.001]. Maximum specific force was significantly greater in NAC-treated mdx muscles [9.80 (2.27) vs 13.07 (3.37)Ncm-2 ; P=0.038]. Increased force in mdx mice was associated with reduced thiol oxidation and inflammation in fast muscles, and increased citrate synthase activity in slow muscle. Importantly, NAC significantly impaired body weight gain in both strains of young growing mice, and reduced liver weight in C57 mice and muscle weight in mdx mice. These potentially adverse effects of NAC emphasise the need for caution when interpreting improvements in muscle function based on normalised force measures, and that careful consideration be given to these effects when proposing NAC as a potential treatment for young DMD boys.