alisporivir and Muscular-Dystrophy--Animal

Duchenne muscular dystrophy (DMD) is a severe muscle disease of known etiology without effective, or generally applicable therapy. Mitochondria are affected by the disease in animal models but whether mitochondrial dysfunction is part of the pathogenesis in patients remains unclear. We show that primary cultures obtained from muscle biopsies of DMD patients display a decrease of the respiratory reserve, a consequence of inappropriate opening of the permeability transition pore (PTP). Treatment with the cyclophilin inhibitor alisporivir - a cyclosporin A derivative that desensitizes the PTP but does not inhibit calcineurin - largely restored the maximal respiratory capacity without affecting basal oxygen consumption in cells from patients, thus reinstating a normal respiratory reserve. Treatment with alisporivir, but not with cyclosporin A, led to a substantial recovery of respiratory function matching improved muscle ultrastructure and survival of sapje zebrafish, a severe model of DMD where muscle defects are close to those of DMD patients. Alisporivir was generally well tolerated in HCV patients and could be used for the treatment of DMD.

Topics: Animals; Cell Respiration; Cells, Cultured; Cyclosporine; Disease Models, Animal; Humans; Membrane Potential, Mitochondrial; Mitochondria; Muscle Cells; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne; Oxygen Consumption; Zebrafish

Muscular dystrophy results in the progressive wasting and necrosis of skeletal muscle. Glucocorticoids such as prednisone have emerged as a front-line treatment for many forms of this disease. Recently, Debio-025, a cyclophilin inhibitor that desensitizes the mitochondrial permeability pore and subsequent cellular necrosis, was shown to improve pathology in three different mouse models of muscular dystrophy. However it is not known if Debio-025 can work in conjunction with prednisone, or how it compares against prednisone in mitigating disease in dystrophic mouse models. Here we show that Debio-025 reduced the variations in myofiber cross-sectional areas, decreased fibrosis, and decreased infiltration of activated macrophages more efficiently than prednisone. However the use of prednisone and Debio-025 together had no additional effect on these histopathological indexes. Orally administered Debio-025 also reduced creatine kinase blood levels and improved grip strength in mdx mice after 6 weeks of treatment, and the combination of Debio-025 with prednisone increased muscle function slightly better than prednisone alone. Thus, our results suggest that Debio-025 is as, effective as or slightly better than, prednisone in mitigating muscular dystrophy in the mdx mouse model of disease.

Topics: Analysis of Variance; Animals; Cyclosporine; Hand Strength; Immunohistochemistry; Male; Mice; Mice, Inbred mdx; Muscle, Skeletal; Muscular Dystrophy, Animal; Prednisone; Treatment Outcome

Duchenne muscular dystrophy (DMD) is a severe muscle wasting disorder caused by the absence of the cytoskeletal protein dystrophin. This leads to muscle cell death accompanied by chronic inflammation. Cyclosporin A (CsA) is a powerful immunosuppressive drug, which has been proposed for DMD treatment. CsA also directly regulates the mitochondrial permeability transition pore (mPTP), which participates in cell death pathways through the inhibition of cyclophilin D. Here, we evaluated whether Debio 025, a cyclophilin inhibitor with no immunosuppressive activity, improves the dystrophic condition in a mouse model of DMD, through regulation of mPTP.. The potency of Debio 025 to protect mouse dystrophic cells against mitochondria-mediated death was assessed by caspase-3 activity and calcium retention capacity assays. Mdx(5Cv) mice (3-week-old) were treated daily by gavage for 2 weeks with Debio 025 (10, 30 or 100 mg kg(-1)), CsA (10 mg kg(-1)) or placebo. The effects on muscle necrosis and function were measured.. In vitro investigations showed protective effect of low concentrations of Debio 025 against cell death. Histology demonstrated that Debio 025 partially protected the diaphragm and soleus muscles against necrosis (10 and 100 mg kg(-1), respectively). Hindlimb muscles from mice receiving Debio 025 at 10 mg kg(-1) relaxed faster, showed alteration in the stimulation frequency-dependent recruitment of muscle fibres and displayed a higher resistance to mechanical stress.. Debio 025 partially improved the structure and the function of the dystrophic mouse muscle, suggesting that therapies targeting the mPTP may be helpful to DMD patients.

Topics: Animals; Animals, Newborn; Cell Death; Cyclophilins; Cyclosporine; Diaphragm; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Delivery Systems; Female; Hindlimb; Male; Mice; Mice, Inbred mdx; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Muscle, Skeletal; Muscular Dystrophy, Animal; Muscular Dystrophy, Duchenne; Necrosis

Muscular dystrophies comprise a diverse group of genetic disorders that lead to muscle wasting and, in many instances, premature death. Many mutations that cause muscular dystrophy compromise the support network that connects myofilament proteins within the cell to the basal lamina outside the cell, rendering the sarcolemma more permeable or leaky. Here we show that deletion of the gene encoding cyclophilin D (Ppif) rendered mitochondria largely insensitive to the calcium overload-induced swelling associated with a defective sarcolemma, thus reducing myofiber necrosis in two distinct models of muscular dystrophy. Mice lacking delta-sarcoglycan (Scgd(-/-) mice) showed markedly less dystrophic disease in both skeletal muscle and heart in the absence of Ppif. Moreover, the premature lethality associated with deletion of Lama2, encoding the alpha-2 chain of laminin-2, was rescued, as were other indices of dystrophic disease. Treatment with the cyclophilin inhibitor Debio-025 similarly reduced mitochondrial swelling and necrotic disease manifestations in mdx mice, a model of Duchenne muscular dystrophy, and in Scgd(-/-) mice. Thus, mitochondrial-dependent necrosis represents a prominent disease mechanism in muscular dystrophy, suggesting that inhibition of cyclophilin D could provide a new pharmacologic treatment strategy for these diseases.

Topics: Animals; Cyclophilins; Cyclosporine; Humans; Laminin; Mice; Mice, Inbred C57BL; Mice, Inbred mdx; Mice, Knockout; Mitochondria, Muscle; Mitochondrial Swelling; Muscle, Skeletal; Muscular Dystrophy, Animal; Myocardium; Necrosis; Peptidyl-Prolyl Isomerase F; Sarcoglycans