A Multidisciplinary Evaluation of the Effectiveness of Cyclosporine A in Dystrophic Mdx Mice

Abstract

Chronic inflammation is a secondary reaction of Duchenne muscular dystrophy and may contribute to disease progression. To examine whether immunosuppressant therapies could benefit dystrophic patients, we analyzed the effects of cyclosporine A (CsA) on a dystrophic mouse model. Mdx mice were treated with 10 mg/kg of CsA for 4 to 8 weeks throughout a period of exercise on treadmill, a protocol that worsens the dystrophic condition. The CsA treatment fully prevented the 60% drop of forelimb strength induced by exercise. A significant amelioration (P < 0.05) was observed in histological profile of CsA-treated gastrocnemius muscle with reductions of nonmuscle area (20%), centronucleated fibers (12%), and degenerating area (50%) compared to untreated exercised mdx mice. Consequently, the percentage of normal fibers increased from 26 to 35% in CsA-treated mice. Decreases in creatine kinase and markers of fibrosis were also observed. By electrophysiological recordings ex vivo, we found that CsA counteracted the decrease in chloride conductance (gCl), a functional index of degeneration in diaphragm and extensor digitorum longus muscle fibers. However, electrophysiology and fura-2 calcium imaging did not show any amelioration of calcium homeostasis in extensor digitorum longus muscle fibers. No significant effect Duchenne muscular dystrophy (DMD) is a fatal genetic disorder for which no definitive cure is available. The X-linked mutation of the dystrophin gene leads to the absence of dystrophin in skeletal muscle fibers, a biochemical defect also observed in the mdx mouse, the murine phenotype of DMD. 1 Dystrophin is a subsarcolemmal protein involved in the link between the contractile machinery and the extracellular matrix. It is generally accepted that the absence of dystrophin weakens the sarcolemma and impairs the transduction of the mechanical signal imposed by the contraction. This leads to a complex and still not fully understood network of interconnected pathogenic events responsible for progressive muscle degeneration; these events involve the increased entrance of calcium, the activation of proteases, and the occurrence of a functional ischemic state. [1][2][3][4] Recent evidence suggests that a chronic inflammatory state is a secondary reaction that strongly contributes to the progression of the pathology. A significant overexpression of inflammatory and immune response genes has been described by microarray in muscle of dystrophic subjects. 5,6 Also, activated helper and cytotoxic T cells have been found to be present in higher number in muscles of dystrophic mdx mice and to promote pathology in this phenotype. 7 According to this view, immunoSupported by Telethon-Italy (to project no. 1150) and the Association Franç ais Contre les Myopathies (as part of postdoctoral fellowships to

Systemic Delivery of Allogenic Muscle Stem Cells Induces Long-Term Muscle Repair and Clinical Efficacy in Duchenne Muscular Dystrophy Dogs

“…Similarly, intra-arterial delivery of wild-type canine Mabs generated persistent clinical amelioration of GRMD dogs. 33 Additionally, since immunosuppressive drugs and anti-inflammatory agents have been extensively described to reduce the severity of muscular dystrophy 77 and improve muscle function, 78,79 we documented the clinical course of treated GRMD dogs in parallel to that of non-immunosuppressed but also immunosuppressed GRMD dogs to clearly show that the clinical benefit could not be attributed to the immunosuppressive regimen. Taking into account that the clinical courses are quite similar inside the mocktreated and the treated dog groups, and are also dramatically distinct between the two groups, the clinical impact determined in the treated GRMD dogs probably cannot be explained alone by the phenotypic variability known among GRMD dogs.…”

Degenerative and regenerative features of myofibers differ among skeletal muscles in a murine model of muscular dystrophy

“…Different muscles have been analyzed in mdx mice after exercise (Weller et al 1990;Brussee et al 1997;Granchelli et al 2000;De Luca et al 2005), administration of drugs (Hodgetts et al 2006), engraftment of somatic cells (Hindi et al 2013;Boldrin et al 2015), and gene modification (Li et al 2009;Heydemann et al 2012). The results obtained and the skeletal muscles analyzed are different in these previous reports.…”

Thérapie cellulaire de la dystrophie musculaire de Duchenne: essai préclinique chez le chien myopathe

“…L'utilisation de cellules allogé-niques non mutées nous a contraints à immunosupprimer les animaux. L'immunosuppression modifie l'expression de la maladie (Radley et al 2007, Miller et al 1997, De Luca et al 2005, mais les effets obtenus sont marqués et tous statistiquement différents des animaux contrôles immunosupprimés.…”