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Lloyd EM, Crew RC, Haynes VR, White RB, Mark PJ, Jackaman C, Papadimitriou JM, Pinniger GJ, Murphy RM, Watt MJ, Grounds MD. Pilot investigations into the mechanistic basis for adverse effects of glucocorticoids in dysferlinopathy. Skelet Muscle 2024; 14:19. [PMID: 39123261 PMCID: PMC11312411 DOI: 10.1186/s13395-024-00350-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Accepted: 07/19/2024] [Indexed: 08/12/2024] Open
Abstract
BACKGROUND Dysferlinopathies are a clinically heterogeneous group of muscular dystrophies caused by gene mutations resulting in deficiency of the membrane-associated protein dysferlin. They manifest post-growth and are characterised by muscle wasting (primarily in the limb and limb-gridle muscles), inflammation, and replacement of myofibres with adipose tissue. The precise pathomechanism for dysferlinopathy is currently unclear; as such there are no treatments currently available. Glucocorticoids (GCs) are widely used to reduce inflammation and treat muscular dystrophies, but when administered to patients with dysferlinopathy, they have unexpected adverse effects, with accelerated loss of muscle strength. METHODS To investigate the mechanistic basis for the adverse effects of GCs in dysferlinopathy, the potent GC dexamethasone (Dex) was administered for 4-5 weeks (0.5-0.75 µg/mL in drinking water) to dysferlin-deficient BLA/J and normal wild-type (WT) male mice, sampled at 5 (Study 1) or 10 months (Study 2) of age. A wide range of analyses were conducted. Metabolism- and immune-related gene expression was assessed in psoas muscles at both ages and in quadriceps at 10 months of age. For the 10-month-old mice, quadriceps and psoas muscle histology was assessed. Additionally, we investigated the impact of Dex on the predominantly slow and fast-twitch soleus and extensor digitorum longus (EDL) muscles (respectively) in terms of contractile function, myofibre-type composition, and levels of proteins related to contractile function and metabolism, plus glycogen. RESULTS At both ages, many complement-related genes were highly expressed in BLA/J muscles, and WT mice were generally more responsive to Dex than BLA/J. The effects of Dex on BLA/J mice included (i) increased expression of inflammasome-related genes in muscles (at 5 months) and (ii) exacerbated histopathology of quadriceps and psoas muscles at 10 months. A novel observation was pronounced staining for glycogen in many myofibres of the damaged quadriceps muscles, with large pale vacuolated myofibres, suggesting possible myofibre death by oncosis. CONCLUSION These pilot studies provide a new focus for further investigation into the adverse effects of GCs on dysferlinopathic muscles.
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Affiliation(s)
- Erin M Lloyd
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, WA, Australia
- Curtin Health Innovation Research Institute, Curtin Medical School, Curtin University, Bentley, WA, Australia
| | - Rachael C Crew
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, WA, Australia
- Department of Obstetrics and Gynaecology, University of Cambridge, Cambridge, UK
| | - Vanessa R Haynes
- Department of Anatomy and Physiology, Faculty of Medicine Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Robert B White
- MD Education Unit, UWA Medical School, The University of Western Australia, Perth, WA, Australia
| | - Peter J Mark
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, WA, Australia
| | - Connie Jackaman
- Curtin Health Innovation Research Institute, Curtin Medical School, Curtin University, Bentley, WA, Australia
| | - John M Papadimitriou
- Department of Pathology and Laboratory Medicine, UWA Medical School, The University of Western Australia, Perth, WA, Australia
| | - Gavin J Pinniger
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, WA, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, VIC, Australia
| | - Matthew J Watt
- Department of Anatomy and Physiology, Faculty of Medicine Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia
| | - Miranda D Grounds
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, WA, Australia.
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Swiderski K, Chan AS, Herold MJ, Kueh AJ, Chung JD, Hardee JP, Trieu J, Chee A, Naim T, Gregorevic P, Lynch GS. The BALB/c.mdx62 mouse exhibits a dystrophic muscle pathology and is a model of Duchenne muscular dystrophy. Dis Model Mech 2024; 17:dmm050502. [PMID: 38602028 PMCID: PMC11095634 DOI: 10.1242/dmm.050502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 03/28/2024] [Indexed: 04/12/2024] Open
Abstract
Duchenne muscular dystrophy (DMD) is a devastating monogenic skeletal muscle-wasting disorder. Although many pharmacological and genetic interventions have been reported in preclinical studies, few have progressed to clinical trials with meaningful benefit. Identifying therapeutic potential can be limited by availability of suitable preclinical mouse models. More rigorous testing across models with varied background strains and mutations can identify treatments for clinical success. Here, we report the generation of a DMD mouse model with a CRISPR-induced deletion within exon 62 of the dystrophin gene (Dmd) and the first generated in BALB/c mice. Analysis of mice at 3, 6 and 12 months of age confirmed loss of expression of the dystrophin protein isoform Dp427 and resultant dystrophic pathology in limb muscles and the diaphragm, with evidence of centrally nucleated fibers, increased inflammatory markers and fibrosis, progressive decline in muscle function, and compromised trabecular bone development. The BALB/c.mdx62 mouse is a novel model of DMD with associated variations in the immune response and muscle phenotype, compared with those of existing models. It represents an important addition to the preclinical model toolbox for developing therapeutic strategies.
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Affiliation(s)
- Kristy Swiderski
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Audrey S. Chan
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Marco J. Herold
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3052, Australia
- Olivia Newton-John Cancer Research Institute, Heidelberg, VIC 3084, Australia
- School of Cancer Medicine, La Trobe University, Heidelberg, VIC 3084, Australia
| | - Andrew J. Kueh
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3052, Australia
- Olivia Newton-John Cancer Research Institute, Heidelberg, VIC 3084, Australia
- School of Cancer Medicine, La Trobe University, Heidelberg, VIC 3084, Australia
| | - Jin D. Chung
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Justin P. Hardee
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Jennifer Trieu
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Annabel Chee
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Timur Naim
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Paul Gregorevic
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Gordon S. Lynch
- Centre for Muscle Research, Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
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Vasterling ME, Maitski RJ, Davis BA, Barnes JE, Kelkar RA, Klapper RJ, Patel H, Ahmadzadeh S, Shekoohi S, Kaye AD, Varrassi G. AMONDYS 45 (Casimersen), a Novel Antisense Phosphorodiamidate Morpholino Oligomer: Clinical Considerations for Treatment in Duchenne Muscular Dystrophy. Cureus 2023; 15:e51237. [PMID: 38283433 PMCID: PMC10821770 DOI: 10.7759/cureus.51237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 12/28/2023] [Indexed: 01/30/2024] Open
Abstract
AMONDYS 45 (casimersen) is an antisense oligonucleotide therapy used to treat Duchenne muscular dystrophy (DMD), a rare genetic disorder characterized by a mutation in the DMD gene. Symptoms include progressive muscle weakness, respiratory and cardiac complications, and premature death. Casimersen targets a specific mutation in the DMD gene that results in the absence of dystrophin protein, a key structural component of muscle fibers. While there is currently no cure for DMD, exon-skipping therapy works by restoring the reading frame of the mutated gene, allowing the production of a partially functional dystrophin protein. Clinical trials of casimersen have shown promising results in increasing dystrophin production, as measured by polymerase chain reaction (PCR) droplets when compared to placebo. In a randomized double-blind trial, patients who received casimersen had significantly higher dystrophin levels when compared to those who received placebo. Casimersen therapy is administered through repeated intravenous infusions, although the optimal dosage and duration of treatment are still under investigation. Based on the completed and ongoing clinical trials, casimersen has been well tolerated, with most adverse events being mild and unrelated to casimersen. In 2021, AMONDYS 45 (casimersen) received approval from the US Food and Drug Administration (FDA) for the treatment of Duchene muscular dystrophy in patients with a mutation of the DMD gene that is amenable to exon 45 skipping. These collective findings indicate that casimersen has the potential to elicit functional changes in individuals with DMD, although further studies are necessary to comprehensively evaluate the specific functional improvements. Regardless, the FDA approval and ongoing clinic trials mark a significant milestone in the development of DMD treatments and offer hope for those affected by this debilitating disease.
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Affiliation(s)
- Megan E Vasterling
- School of Medicine, Louisiana State University Health Sciences Center, New Orleans, USA
| | - Rebecca J Maitski
- School of Medicine, Louisiana State University Health Sciences Center, New Orleans, USA
| | - Brice A Davis
- School of Medicine, Louisiana State University Health Sciences Center, New Orleans, USA
| | - Julie E Barnes
- School of Medicine, Louisiana State University Health Sciences Center, New Orleans, USA
| | - Rucha A Kelkar
- School of Medicine, Medical University of South Carolina, Charleston, USA
| | - Rachel J Klapper
- Radiology, Louisiana State University Health Sciences Center, Shreveport, USA
| | - Hirni Patel
- Anesthesiology, Louisiana State University Health Sciences Center, Shreveport, USA
| | - Shahab Ahmadzadeh
- Anesthesiology, Louisiana State University Health Sciences Center, Shreveport, USA
| | - Sahar Shekoohi
- Anesthesiology, Louisiana State University Health Sciences Center, Shreveport, USA
| | - Alan D Kaye
- Anesthesiology, Louisiana State University Health Sciences Center, Shreveport, USA
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