Duchenne muscular dystrophy (DMD) is a devastating X-linked disease affecting ~1 in 5000 males. DMD patients exhibit progressive muscle degeneration and weakness, leading to loss of ambulation and ...premature death from cardiopulmonary failure. We previously reported that mouse Laminin-111 (msLam-111) protein could reduce muscle pathology and improve muscle function in the mdx mouse model for DMD. In this study, we examined the ability of msLam-111 to prevent muscle disease progression in the golden retriever muscular dystrophy (GRMD) dog model of DMD. The msLam-111 protein was injected into the cranial tibial muscle compartment of GRMD dogs and muscle strength and pathology were assessed. The results showed that msLam-111 treatment increased muscle fiber regeneration and repair with improved muscle strength and reduced muscle fibrosis in the GRMD model. Together, these findings support the idea that Laminin-111 could serve as a novel protein therapy for the treatment of DMD.
ABSTRACT
Introduction: Duchenne muscular dystrophy (DMD) and golden retriever muscular dystrophy (GRMD) are X‐linked disorders caused by mutations in the DMD gene. Autophagy was recently identified ...as a secondary therapeutic target for DMD. We hypothesized that autophagy would be reduced in GRMD. Methods: Autophagic gene and protein expression was assessed in normal and GRMD skeletal muscles and correlated with phenotypic biomarkers. Results: Muscles were differentially affected. Autophagy gene levels were lower than normal in the GRMD cranial sartorius (CS) but similar in the vastus lateralis (VL). Protein markers of autophagic flux, LC3B‐II and p62, were higher in both GRMD muscles, in keeping with impaired autophagy. Protein levels correlated with a more severe phenotype. Autophagic structures were found in necrotic, fast‐twitch GRMD myofibers. Discussion: Our data suggest that autophagy is impaired in certain GRMD muscles. Differential GRMD CS involvement emphasizes that therapeutic modulation of autophagy could require specific muscle targeting. Muscle Nerve 58: 418–426, 2018
The expression of N-glycolylneuraminic acid (Neu5Gc) and the cytotoxic T cell (CT) carbohydrate can impact the severity of muscular dystrophy arising from the loss of dystrophin in mdx mice. Here, we ...describe the expression of these two glycans in skeletal muscles of dogs and humans with or without dystrophin-deficiency. Neu5Gc expression was highly reduced (>95%) in muscle from normal golden retriever crosses (GR, n = 3) and from golden retriever with muscular dystrophy (GRMD, n = 5) dogs at multiple ages (3, 6 and 13 months) when compared to mouse muscle, however, overall sialic acid expression in GR and GRMD muscles remained high at all ages. Neu5Gc was expressed on only a minority of GRMD satellite cells, CD8⁺ T lymphocytes and macrophages. Human muscle from normal (no evident disease, n = 3), Becker (BMD, n = 3) and Duchenne (DMD, n = 3) muscular dystrophy individuals had absent to very low Neu5Gc staining, but some punctate intracellular muscle staining was present in BMD and DMD muscles. The CT carbohydrate was localized to the neuromuscular junction in GR muscle, while GRMD muscles had increased expression on a subset of myofibers and macrophages. In humans, the CT carbohydrate was ectopically expressed on the sarcolemmal membrane of some BMD muscles, but not normal human or DMD muscles. These data are consistent with the notion that altered Neu5Gc and CT carbohydrate expression may modify disease severity resulting from dystrophin deficiency in dogs and humans.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Duchenne muscular dystrophy (DMD) is a dystrophin-deficient lethal muscle disease. To date, the catastrophic muscle wasting phenotype has only been seen in dystrophin-deficient humans and dogs. ...Although Duchenne-like symptoms have been observed in more than a dozen dog breeds, the mutation is often not known and research colonies are rarely established. Here, we report an independent canine DMD model originally derived from the Pembroke Welsh corgi breed. The affected dogs presented clinical signs of muscular dystrophy. Immunostaining revealed the absence of dystrophin and upregulation of utrophin. Histopathologic examination showed variable fiber size, central nucleation, calcification, fibrosis, neutrophil and macrophage infiltration and cardiac focal vacuolar degeneration. Carrier dogs also displayed mild myopathy. The mutation was identified as a long interspersed repetitive element-1 (LINE-1) insertion in intron 13, which introduced a new exon containing an in-frame stop codon. Similar mutations have been seen in human patients. A colony was generated by crossing carrier females with normal males. Affected puppies had a normal birth weight but they experienced a striking growth delay in the first 5 days. In summary, the new corgi DMD model offers an excellent opportunity to study DMD pathogenesis and to develop novel therapies.
The availability of an in vitro canine cell line would reduce the need for dogs for primary in vitro cell culture and reduce overall cost in pre-clinical studies. An immortalized canine muscle cell ...line, named Myok9, from primary myoblasts of a normal dog has been developed by the authors. Immortalization was performed by SV40 viral transfection of the large T antigen into the primary muscle cells. Proliferation assays, growth curves, quantitative PCR, western blotting, mass spectrometry, and light microscopy were performed to characterize the MyoK9 cell line at different stages of growth and differentiation. The expression of muscle-related genes was determined to assess myogenic origin. Myok9 cells expressed dystrophin and other muscle-specific proteins during differentiation, as detected with mass spectrometry and western blotting. Using the Myok9 cell line, new therapies before moving to pre-clinical studies to enhance the number and speed of analyses and reduce the cost of early experimentation can be tested now. This cell line will be made available to the research community to further evaluate potential therapeutics.
In Duchenne muscular dystrophy (DMD), abnormal cardiac function is typically preceded by a decade of skeletal muscle disease. Molecular reasons for differences in onset and progression of these ...muscle groups are unknown. Human biomarkers are lacking.
We analyzed cardiac and skeletal muscle microarrays from normal and golden retriever muscular dystrophy (GRMD) dogs (ages 6, 12, or 47+ mo) to gain insight into muscle dysfunction and to identify putative DMD biomarkers. These biomarkers were then measured using human DMD blood samples.
We identified GRMD candidate genes that might contribute to the disparity between cardiac and skeletal muscle disease, focusing on brain-derived neurotropic factor (BDNF) and osteopontin (OPN/SPP1, hereafter indicated as SPP1). BDNF was elevated in cardiac muscle of younger GRMD but was unaltered in skeletal muscle, while SPP1 was increased only in GRMD skeletal muscle. In human DMD, circulating levels of BDNF were inversely correlated with ventricular function and fibrosis, while SPP1 levels correlated with skeletal muscle function.
These results highlight gene expression patterns that could account for differences in cardiac and skeletal disease in GRMD. Most notably, animal model-derived data were translated to DMD and support use of BDNF and SPP1 as biomarkers for cardiac and skeletal muscle involvement, respectively.
Background Duchenne muscular dystrophy (DMD) is an X-linked disease that causes progressive muscle weakness. Affected boys typically die from respiratory or cardiac failure. Golden retriever muscular ...dystrophy (GRMD) is genetically homologous with DMD and causes analogous skeletal and cardiac muscle disease. Previous studies have detailed features of GRMD cardiomyopathy in mostly young dogs. Cardiac disease is not well characterized in adult GRMD dogs, and cardiac magnetic resonance (CMR) imaging studies have not been completed. Methods and Results We evaluated echocardiography and CMR in 24 adult GRMD dogs at different ages. Left ventricular systolic and diastolic functions, wall thickness, and myocardial strain were assessed with echocardiography. Features evaluated with CMR included left ventricular function, chamber size, myocardial mass, and late gadolinium enhancement. Our results largely paralleled those of DMD cardiomyopathy. Ejection fraction and fractional shortening correlated well with age, with systolic dysfunction occurring at ≈30 to 45 months. Circumferential strain was more sensitive than ejection fraction in early disease detection. Evidence of left ventricular chamber dilatation provided proof of dilated cardiomyopathy. Late gadolinium enhancement imaging showed DMD-like left ventricular lateral wall lesions and earlier involvement of the anterior septum. Multiple functional indexes were graded objectively and added, with and without late gadolinium enhancement, to give cardiac and cardiomyopathy scores of disease severity. Consistent with DMD, there was parallel skeletal muscle involvement, as tibiotarsal joint flexion torque declined in tandem with cardiac function. Conclusions This study established parallels of progressive cardiomyopathy between dystrophic dogs and boys, further validating GRMD as a model of DMD cardiac disease.
The paradox of muscle hypertrophy in muscular dystrophy Kornegay, Joe N; Childers, Martin K; Bogan, Daniel J ...
Physical medicine and rehabilitation clinics of North America,
02/2012, Letnik:
23, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Mutations in the dystrophin gene cause Duchenne and Becker muscular dystrophy in humans and syndromes in mice, dogs, and cats. Affected humans and dogs have progressive disease that leads primarily ...to muscle atrophy. Mdx mice progress through an initial phase of muscle hypertrophy followed by atrophy. Cats have persistent muscle hypertrophy. Hypertrophy in humans has been attributed to deposition of fat and connective tissue (pseudohypertrophy). Increased muscle mass (true hypertrophy) has been documented in animal models. Muscle hypertrophy can exaggerate postural instability and joint contractures. Deleterious consequences of muscle hypertrophy should be considered when developing treatments for muscular dystrophy.
Duchenne's muscular dystrophy (DMD) is a severe muscle wasting disorder characterized by the loss of dystrophin expression, muscle necrosis, inflammation and fibrosis. Ongoing muscle regeneration is ...impaired by persistent cytokine stress, further decreasing muscle function. Patients with DMD rarely survive beyond their early 20s, with cardiac and respiratory dysfunction being the primary cause of death. Despite an increase in our understanding of disease progression as well as promising preclinical animal models for therapeutic intervention, treatment options for muscular dystrophy remain limited and novel therapeutic targets are required. Many reports suggest that the TGFβ signalling pathway is activated in dystrophic muscle and contributes to the pathology of DMD in part by impairing the differentiation of myoblasts into mature myofibers. Here, we show that in vitro knockdown of the Ste20-like kinase, SLK, can partially restore myoblast differentiation downstream of TGFβ in a Smad2/3 independent manner. In an mdx model, we demonstrate that SLK is expressed at high levels in regenerating myofibers. Muscle-specific deletion of SLK reduced leukocyte infiltration, increased myogenin and utrophin expression and enhanced differentiation. This was accompanied by resistance to eccentric contraction-induced injury in slow fiber type-enriched soleus muscles. Finally, we found that these effects were partially dependent on the upregulation of p38 signalling. Collectively, these results demonstrate that SLK downregulation can restore some aspects of disease progression in DMD.
•Sustained TGFβ signalling is a hallmark of DMD and is an anti-myogenic cytokine.•The Ste20-like kinase SLK is overexpressed in mdx diaphragm muscles.•Deletion of SLK activates p38 and induces Myogenin expression in mdx muscles.•Deletion of SLK blocks some of the anti-myogenic effects of TGFβ by activating p38.•The SLK-p38 axis may represent a novel therapeutic avenue for DMD patients.
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