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Laminin-111 protein therapy prevents muscle disease in the mdx mouse model for Duchenne muscular dystrophy.

ABSTRACT: Duchenne muscular dystrophy (DMD) is a devastating neuromuscular disease caused by mutations in the gene encoding dystrophin. Loss of dystrophin results in reduced sarcolemmal integrity and increased susceptibility to muscle damage. The alpha(7)beta(1)-integrin is a laminin-binding protein up-regulated in the skeletal muscle of DMD patients and in the mdx mouse model. Transgenic overexpression of the alpha(7)-integrin alleviates muscle disease in dystrophic mice, making this gene a target for pharmacological intervention. Studies suggest laminin may regulate alpha(7)-integrin expression. To test this hypothesis, mouse and human myoblasts were treated with laminin and assayed for alpha(7)-integrin expression. We show that laminin-111 (alpha(1), beta(1), gamma(1)), which is expressed during embryonic development but absent in normal or dystrophic skeletal muscle, increased alpha(7)-integrin expression in mouse and DMD patient myoblasts. Injection of laminin-111 protein into the mdx mouse model of DMD increased expression of alpha(7)-integrin, stabilized the sarcolemma, restored serum creatine kinase to wild-type levels, and protected muscle from exercised-induced damage. These findings demonstrate that laminin-111 is a highly potent therapeutic agent for the mdx mouse model of DMD and represents a paradigm for the systemic delivery of extracellular matrix proteins as therapies for genetic diseases.

SUBMITTER: Rooney JE

PROVIDER: S-EPMC2683113 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature

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Laminin-111 protein therapy prevents muscle disease in the mdx mouse model for Duchenne muscular dystrophy.

Rooney Jachinta E JE Gurpur Praveen B PB Burkin Dean J DJ

Proceedings of the National Academy of Sciences of the United States of America 20090428 19

Duchenne muscular dystrophy (DMD) is a devastating neuromuscular disease caused by mutations in the gene encoding dystrophin. Loss of dystrophin results in reduced sarcolemmal integrity and increased susceptibility to muscle damage. The alpha(7)beta(1)-integrin is a laminin-binding protein up-regulated in the skeletal muscle of DMD patients and in the mdx mouse model. Transgenic overexpression of the alpha(7)-integrin alleviates muscle disease in dystrophic mice, making this gene a target for ph ...[more]

PMID: 19416897

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Project description:Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy caused by mutations in the dystrophin gene. Loss of dystrophin initiates a progressive decline in skeletal muscle integrity and contractile capacity which weakens respiratory muscles including the diaphragm, culminating in respiratory failure, the leading cause of morbidity and mortality in DMD patients. At present, corticosteroid treatment is the primary pharmacological intervention in DMD, but has limited efficacy and adverse side effects. Thus, there is an urgent need for new safe, cost-effective, and rapidly implementable treatments that slow disease progression. One promising new approach is the amplification of nitric oxide-cyclic guanosine monophosphate (NO-cGMP) signalling pathways with phosphodiesterase 5 (PDE5) inhibitors. PDE5 inhibitors serve to amplify NO signalling that is attenuated in many neuromuscular diseases including DMD. We report here that a 14-week treatment of the mdx mouse model of DMD with the PDE5 inhibitor sildenafil (Viagra(®), Revatio(®)) significantly reduced mdx diaphragm muscle weakness without impacting fatigue resistance. In addition to enhancing respiratory muscle contractility, sildenafil also promoted normal extracellular matrix organization. PDE5 inhibition slowed the establishment of mdx diaphragm fibrosis and reduced matrix metalloproteinase-13 (MMP-13) expression. Sildenafil also normalized the expression of the pro-fibrotic (and pro-inflammatory) cytokine tumour necrosis factor ? (TNF?). Sildenafil-treated mdx diaphragms accumulated significantly less Evans Blue tracer dye than untreated controls, which is also indicative of improved diaphragm muscle health. We conclude that sildenafil-mediated PDE5 inhibition significantly reduces diaphragm respiratory muscle dysfunction and pathology in the mdx mouse model of Duchenne muscular dystrophy. This study provides new insights into the therapeutic utility of targeting defects in NO-cGMP signalling with PDE5 inhibitors in dystrophin-deficient muscle.

Project description:BackgroundDuchenne muscular dystrophy (DMD) is caused by loss of dystrophin expression and leads to severe ambulatory and cardiac function decline. However, the dystrophin-deficient mdx murine model of DMD only develops a very mild form of the disease. Our group and others have shown vascular abnormalities in animal models of MD, a likely consequence of the fact that blood vessels express the same dystrophin-associated glycoprotein complex (DGC) proteins as skeletal muscles.MethodsTo test the blood vessel contribution to muscle damage in DMD, mdx 4cv mice were given elevated lipid levels via apolipoprotein E (ApoE) gene knockout combined with normal chow or lipid-rich Western diets. Ambulatory function and heart function (via echocardiogram) were assessed at 4 and 7 months of age. After sacrifice, muscle histology and aortic staining were used to assess muscle pathology and atherosclerosis development, respectively. Plasma levels of total cholesterol, high-density lipoprotein (HDL), triglycerides, and creatine kinase (CK) were also measured.ResultsAlthough there was an increase in left ventricular heart volume in mdx-ApoE mice compared to that in mdx mice, parameters of heart function were not affected. Compared with wild-type and ApoE-null, only mdx-ApoE KO mice showed significant ambulatory dysfunction. Despite no significant difference in plasma CK, histological analyses revealed that elevated plasma lipids in chow- and Western diet-fed mdx-ApoE mice was associated with severe exacerbation of muscle pathology compared to mdx mice: significant increase in myofiber damage and fibrofatty replacement in the gastrocnemius and triceps brachii muscles, more reminiscent of human DMD pathology. Finally, although both ApoE and mdx-ApoE groups displayed increased plasma lipids, mdx-ApoE exhibited atherosclerotic plaque deposition equal to or less than that of ApoE mice.ConclusionsSince others have shown that lipid abnormalities correlate with DMD severity, our data suggest that plasma lipids could be primary contributors to human DMD severity and that the notoriously mild phenotype of mdx mice might be attributable in part to their endogenously low plasma lipid profiles. Hence, DMD patients may benefit from lipid-lowering and vascular-targeted therapies.

Dataset Information

Laminin-111 protein therapy prevents muscle disease in the mdx mouse model for Duchenne muscular dystrophy.

Publications

Laminin-111 protein therapy prevents muscle disease in the mdx mouse model for Duchenne muscular dystrophy.

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