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Roger AL, Biswas DD, Huston ML, Le D, Bailey AM, Pucci LA, Shi Y, Robinson-Hamm J, Gersbach CA, ElMallah MK. Respiratory characterization of a humanized Duchenne muscular dystrophy mouse model. Respir Physiol Neurobiol 2024; 326:104282. [PMID: 38782084 DOI: 10.1016/j.resp.2024.104282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/07/2024] [Accepted: 05/17/2024] [Indexed: 05/25/2024]
Abstract
Duchenne muscular dystrophy (DMD) is the most common X-linked disease. DMD is caused by a lack of dystrophin, a critical structural protein in striated muscle. Dystrophin deficiency leads to inflammation, fibrosis, and muscle atrophy. Boys with DMD have progressive muscle weakness within the diaphragm that results in respiratory failure in the 2nd or 3rd decade of life. The most common DMD mouse model - the mdx mouse - is not sufficient for evaluating genetic medicines that specifically target the human DMD (hDMD) gene sequence. Therefore, a novel transgenic mouse carrying the hDMD gene with an exon 52 deletion was created (hDMDΔ52;mdx). We characterized the respiratory function and pathology in this model using whole body plethysmography, histology, and immunohistochemistry. At 6-months-old, hDMDΔ52;mdx mice have reduced maximal respiration, neuromuscular junction pathology, and fibrosis throughout the diaphragm, which worsens at 12-months-old. In conclusion, the hDMDΔ52;mdx exhibits moderate respiratory pathology, and serves as a relevant animal model to study the impact of novel genetic therapies, including gene editing, on respiratory function.
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Affiliation(s)
- Angela L Roger
- Department of Pediatrics, Duke University, Durham, NC, USA
| | | | | | - Davina Le
- Department of Pediatrics, Duke University, Durham, NC, USA
| | - Aidan M Bailey
- Department of Pediatrics, Duke University, Durham, NC, USA
| | - Logan A Pucci
- Department of Pediatrics, Duke University, Durham, NC, USA
| | - Yihan Shi
- Department of Pediatrics, Duke University, Durham, NC, USA
| | | | | | - Mai K ElMallah
- Department of Pediatrics, Duke University, Durham, NC, USA.
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2
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Maxwell MN, Marullo AL, Valverde-Pérez E, Slyne AD, Murphy BT, O'Halloran KD. Chronic N-acetyl cysteine treatment does not improve respiratory system performance in the mdx mouse model of Duchenne muscular dystrophy. Exp Physiol 2024. [PMID: 38867461 DOI: 10.1113/ep091862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Accepted: 05/10/2024] [Indexed: 06/14/2024]
Abstract
Duchenne muscular dystrophy (DMD) is characterised by respiratory muscle injury, inflammation, fibrosis and weakness, ultimately culminating in respiratory failure. The dystrophin-deficient mouse model of DMD (mdx) shows evidence of respiratory muscle remodelling and dysfunction contributing to impaired respiratory system performance. The antioxidant N-acetylcysteine (NAC) has been shown to exert anti-inflammatory and anti-fibrotic effects leading to improved respiratory muscle performance in a range of animal models of muscle dysfunction, including mdx mice, following short-term administration (2 weeks). We sought to build on previous work by exploring the effects of chronic NAC administration (3 months) on respiratory system performance in mdx mice. One-month-old male mdx mice were randomised to receive normal drinking water (n = 30) or 1% NAC in the drinking water (n = 30) for 3 months. At 4 months of age, we assessed breathing in conscious mice by plethysmography followed by ex vivo assessment of diaphragm force-generating capacity. Additionally, diaphragm histology was performed. In separate studies, in anaesthetised mice, respiratory electromyogram (EMG) activity and inspiratory pressure across a range of behaviours were determined, including assessment of peak inspiratory pressure-generating capacity. NAC treatment did not affect force-generating capacity of the mdx diaphragm. Collagen content and immune cell infiltration were unchanged in mdx + NAC compared with mdx diaphragms. Additionally, there was no significant effect of NAC on breathing, ventilatory responsiveness, inspiratory EMG activity or inspiratory pressure across the range of behaviours from basal conditions to peak system performance. We conclude that chronic NAC treatment has no apparent beneficial effects on respiratory system performance in the mdx mouse model of DMD suggesting limited potential of NAC treatment alone for human DMD.
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Affiliation(s)
| | | | - Esther Valverde-Pérez
- Departamento de Bioquímica y Biología Molecular y Fisiología, Facultad de Medicina, Universidad de Valladolid, Valladolid, Spain
- Unidad de Excelencia Instituto Biomedicina y Genética Molecular (IBGM), Universidad de Valladolid-CSIC, Valladolid, Spain
| | - Aoife D Slyne
- Department of Physiology, University College Cork, Cork, Ireland
| | - Ben T Murphy
- Department of Physiology, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, University College Cork, Cork, Ireland
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Ó Murchú SC, O'Halloran KD. BREATHE DMD: boosting respiratory efficacy after therapeutic hypoxic episodes in Duchenne muscular dystrophy. J Physiol 2024. [PMID: 38837229 DOI: 10.1113/jp280280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 05/12/2024] [Indexed: 06/07/2024] Open
Abstract
Duchenne muscular dystrophy (DMD) is a fatal genetic neuromuscular disorder, characterised by progressive decline in skeletal muscle function due to the secondary consequences of dystrophin deficiency. Weakness extends to the respiratory musculature, and cardiorespiratory failure is the leading cause of death in men with DMD. Intermittent hypoxia has emerged as a potential therapy to counteract ventilatory insufficiency by eliciting long-term facilitation of breathing. Mechanisms of sensory and motor facilitation of breathing have been well delineated in animal models. Various paradigms of intermittent hypoxia have been designed and implemented in human trials culminating in clinical trials in people with spinal cord injury and amyotrophic lateral sclerosis. Application of therapeutic intermittent hypoxia to DMD is considered together with discussion of the potential barriers to progression owing to the complexity of this devastating disease. Notwithstanding the considerable challenges and potential pitfalls of intermittent hypoxia-based therapies for DMD, we suggest it is incumbent on the research community to explore the potential benefits in pre-clinical models. Intermittent hypoxia paradigms should be implemented to explore the proclivity to express respiratory plasticity with the longer-term aim of preserving and potentiating ventilation in pre-clinical models and people with DMD.
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Affiliation(s)
- Seán C Ó Murchú
- Department of Physiology, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, University College Cork, Cork, Ireland
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Li Q, Liang F, Bhattarai S, Divangahi M, Kaufmann E, Petrof BJ. Dynamic equilibrium of skeletal muscle macrophage ontogeny in the diaphragm during homeostasis, injury, and recovery. Sci Rep 2024; 14:9132. [PMID: 38644379 PMCID: PMC11033281 DOI: 10.1038/s41598-024-59527-0] [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: 11/13/2023] [Accepted: 04/11/2024] [Indexed: 04/23/2024] Open
Abstract
The diaphragm is a unique skeletal muscle due to its continuous activation pattern during the act of breathing. The ontogeny of macrophages, pivotal cells for skeletal muscle maintenance and regeneration, is primarily based on two distinct origins: postnatal bone marrow-derived monocytes and prenatal embryonic progenitors. Here we employed chimeric mice to study the dynamics of these two macrophage populations under different conditions. Traditional chimeric mice generated through whole body irradiation showed virtually complete elimination of the original tissue-resident macrophage pool. We then developed a novel method which employs lead shielding to protect the diaphragm tissue niche from irradiation. This allowed us to determine that up to almost half of tissue-resident macrophages in the diaphragm can be maintained independently from bone marrow-derived monocytes under steady-state conditions. These findings were confirmed by long-term (5 months) parabiosis experiments. Acute diaphragm injury shifted the macrophage balance toward an overwhelming predominance of bone marrow (monocyte)-derived macrophages. However, there was a remarkable reversion to the pre-injury ontological landscape after diaphragm muscle recovery. This diaphragm shielding method permits analysis of the dynamics of macrophage origin and corresponding function under different physiological and pathological conditions. It may be especially useful for studying diseases which are characterized by acute or chronic injury of the diaphragm and accompanying inflammation.
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Affiliation(s)
- Qian Li
- Meakins-Christie Laboratories, Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, EM3.2224, Montreal, QC, H4A 3J1, Canada
| | - Feng Liang
- Meakins-Christie Laboratories, Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, EM3.2224, Montreal, QC, H4A 3J1, Canada
| | - Salyan Bhattarai
- Meakins-Christie Laboratories, Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, EM3.2224, Montreal, QC, H4A 3J1, Canada
| | - Maziar Divangahi
- Meakins-Christie Laboratories, Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, EM3.2224, Montreal, QC, H4A 3J1, Canada
| | - Eva Kaufmann
- Meakins-Christie Laboratories, Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, EM3.2224, Montreal, QC, H4A 3J1, Canada
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Basil J Petrof
- Meakins-Christie Laboratories, Translational Research in Respiratory Diseases Program, Research Institute of the McGill University Health Centre, 1001 Decarie Boulevard, EM3.2224, Montreal, QC, H4A 3J1, Canada.
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Song Y, Xu K, Xu HY, Guo YK, Xu R, Fu H, Yuan WF, Zhou ZQ, Xu T, Chen XJ, Wang YL, Fu C, Zhou H, Cai XT, Li XS. Longitudinal changes in magnetic resonance imaging biomarkers of the gluteal muscle groups and functional ability in Duchenne muscular dystrophy: a 12-month cohort study. Pediatr Radiol 2023; 53:2672-2682. [PMID: 37889296 PMCID: PMC10697878 DOI: 10.1007/s00247-023-05791-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 10/08/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023]
Abstract
BACKGROUND Quantitative magnetic resonance imaging (MRI) is considered an objective biomarker of Duchenne muscular dystrophy (DMD), but the longitudinal progression of MRI biomarkers in gluteal muscle groups and their predictive value for future motor function have not been described. OBJECTIVE To explore MRI biomarkers of the gluteal muscle groups as predictors of motor function decline in DMD by characterizing the progression over 12 months. MATERIALS AND METHODS A total of 112 participants with DMD were enrolled and underwent MRI examination of the gluteal muscles to determine fat fraction and longitudinal relaxation time (T1). Investigations were based on gluteal muscle groups including flexors, extensors, adductors, and abductors. The North Star Ambulatory Assessment and timed functional tests were performed. All participants returned for follow-up at an average of 12 months and were divided into two subgroups (functional stability/decline groups) based on changes in timed functional tests. Univariable and multivariable logistic regression methods were used to explore the risk factors associated with future motor function decline. RESULTS For the functional decline group, all T1 values decreased, while fat fraction values increased significantly over 12 months (P<0.05). For the functional stability group, only the fat fraction of the flexors and abductors increased significantly over 12 months (P<0.05). The baseline T1 value was positively correlated with North Star Ambulatory Assessment and negatively correlated with timed functional tests at the 12-month follow-up (P<0.001), while the baseline fat fraction value was negatively correlated with North Star Ambulatory Assessment and positively correlated with timed functional tests at the 12-month follow-up (P<0.001). Multivariate regression showed that increased fat fraction of the abductors was associated with future motor function decline (model 1: odds ratio [OR]=1.104, 95% confidence interval [CI]: 1.026~1.187, P=0.008; model 2: OR=1.085, 95% CI: 1.013~1.161, P=0.019), with an area under the curve of 0.874. CONCLUSION Fat fraction of the abductors is a powerful predictor of future motor functional decline in DMD patients at 12 months, underscoring the importance of focusing early on this parameter in patients with DMD.
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Affiliation(s)
- Yu Song
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Ke Xu
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Hua-Yan Xu
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Ying-Kun Guo
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Rong Xu
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Hang Fu
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Wei-Feng Yuan
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Zi-Qi Zhou
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Ting Xu
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Xi-Jian Chen
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Yi-Lei Wang
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Chuan Fu
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Hui Zhou
- Department of Rehabilitation Medicine, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Xiao-Tang Cai
- Department of Rehabilitation Medicine, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Xue-Sheng Li
- Department of Radiology, Key Laboratory of Obstetric and Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, 610041, China.
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6
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Mucha O, Myszka M, Podkalicka P, Świderska B, Malinowska A, Dulak J, Łoboda A. Proteome Profiling of the Dystrophic mdx Mice Diaphragm. Biomolecules 2023; 13:1648. [PMID: 38002330 PMCID: PMC10669179 DOI: 10.3390/biom13111648] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/02/2023] [Accepted: 11/08/2023] [Indexed: 11/26/2023] Open
Abstract
Mdx mice with a spontaneous mutation in exon 23 of the Dmd gene represent the most common model to investigate the pathophysiology of Duchenne muscular dystrophy (DMD). The disease, caused by the lack of functional dystrophin, is characterized by irreversible impairment of muscle functions, with the diaphragm affected earlier and more severely than other skeletal muscles. We applied a label-free (LF) method and the more thorough tandem mass tag (TMT)-based method to analyze differentially expressed proteins in the diaphragm of 6-week-old mdx mice. The comparison of both methods revealed 88 commonly changed proteins. A more in-depth analysis of the TMT-based method showed 953 significantly changed proteins, with 867 increased and 86 decreased in dystrophic animals (q-value < 0.05, fold-change threshold: 1.5). Consequently, several dysregulated processes were demonstrated, including the immune response, fibrosis, translation, and programmed cell death. Interestingly, in the dystrophic diaphragm, we found a significant decrease in the expression of enzymes generating hydrogen sulfide (H2S), suggesting that alterations in the metabolism of this gaseous mediator could modulate DMD progression, which could be a potential target for pharmacological intervention.
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Affiliation(s)
- Olga Mucha
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
| | - Małgorzata Myszka
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
- Doctoral School of Exact and Natural Sciences, Łojasiewicza 11 Street, 30-348 Kraków, Poland
| | - Paulina Podkalicka
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
| | - Bianka Świderska
- Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a Street, 02-106 Warsaw, Poland; (B.Ś.); (A.M.)
| | - Agata Malinowska
- Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a Street, 02-106 Warsaw, Poland; (B.Ś.); (A.M.)
| | - Józef Dulak
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
| | - Agnieszka Łoboda
- Department of Medical Biotechnology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, Gronostajowa 7 Street, 30-387 Kraków, Poland; (O.M.); (M.M.); (P.P.); (J.D.)
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O'Halloran KD, Maxwell MN, Marullo AL, Hamilton CP, Ó Murchú SC, Burns DP, Mahony CM, Slyne AD, Drummond SE. Loss of compensation afforded by accessory muscles of breathing leads to respiratory system compromise in the mdx mouse model of Duchenne muscular dystrophy. J Physiol 2023; 601:4441-4467. [PMID: 37688347 DOI: 10.1113/jp285203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 08/18/2023] [Indexed: 09/10/2023] Open
Abstract
Despite profound diaphragm weakness, peak inspiratory pressure-generating capacity is preserved in young mdx mice revealing adequate compensation by extra-diaphragmatic muscles of breathing in early dystrophic disease. We hypothesised that loss of compensation gives rise to respiratory system compromise in advanced dystrophic disease. Studies were performed in male wild-type (n = 196) and dystrophin-deficient mdx mice (n = 188) at 1, 4, 8, 12 and 16 months of age. In anaesthetised mice, inspiratory pressure and obligatory and accessory respiratory EMG activities were recorded during baseline and sustained tracheal occlusion for up to 30-40 s to evoke peak system activation to task failure. Obligatory inspiratory EMG activities were lower in mdx mice across the ventilatory range to peak activity, emerging in early dystrophic disease. Early compensation protecting peak inspiratory pressure-generating capacity in mdx mice, which appears to relate to transforming growth factor-β1-dependent fibrotic remodelling of the diaphragm and preserved accessory muscle function, was lost at 12 and 16 months of age. Denervation and surgical lesion of muscles of breathing in 4-month-old mice revealed a greater dependency on diaphragm for peak inspiratory performance in wild-type mice, whereas mdx mice were heavily dependent upon accessory muscles (including abdominal muscles) for peak performance. Accessory EMG activities were generally preserved or enhanced in young mdx mice, but peak EMG activities were lower than wild-type by 12 months of age. In general, ventilation was reasonably well protected in mdx mice until 16 months of age. Despite the early emergence of impairments in the principal obligatory muscles of breathing, peak inspiratory performance is compensated in early dystrophic disease due to diaphragm remodelling and facilitated contribution by accessory muscles of breathing. Loss of compensation afforded by accessory muscles underpins the emergence of respiratory system morbidity in advanced dystrophic disease. KEY POINTS: Despite diaphragm weakness, peak inspiratory performance is preserved in young dystrophin-deficient mdx mice revealing adequate compensation by extra-diaphragmatic muscles. Peak obligatory muscle (diaphragm, external intercostal, and parasternal intercostal) EMG activities are lower in mdx mice, emerging early in dystrophic disease, before the temporal decline in peak performance. Peak EMG activities of some accessory muscles are lower, whereas others are preserved. There is greater recruitment of the trapezius muscle in mdx mice during peak system activation. In phrenicotomised mice with confirmed diaphragm paralysis, there is a greater contribution made by extra-diaphragmatic muscles to peak inspiratory pressure in mdx compared with wild-type mice. Surgical lesion of accessory (including abdominal) muscles adversely affects peak pressure generation in mdx mice. Diaphragm remodelling leading to stiffening provides a mechanical advantage to peak pressure generation via the facilitated action of extra-diaphragmatic muscles in early dystrophic disease. Peak accessory EMG activities are lower in 12-month-old mdx compared to wild-type mice. Peak inspiratory pressure declines in mdx mice with advanced disease. We conclude that compensation afforded by accessory muscles of breathing declines in advanced dystrophic disease precipitating the emergence of respiratory system dysfunction.
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Affiliation(s)
- Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Michael N Maxwell
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Anthony L Marullo
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Chantelle P Hamilton
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Seán C Ó Murchú
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - David P Burns
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Conor M Mahony
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Aoife D Slyne
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
| | - Sarah E Drummond
- Department of Physiology, School of Medicine, College of Medicine and Health, University College Cork, Cork, Ireland
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Marullo AL, O'Halloran KD. Microbes, metabolites and muscle: Is the gut-muscle axis a plausible therapeutic target in Duchenne muscular dystrophy? Exp Physiol 2023; 108:1132-1143. [PMID: 37269541 PMCID: PMC10988500 DOI: 10.1113/ep091063] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 05/17/2023] [Indexed: 06/05/2023]
Abstract
NEW FINDINGS What is the topic of this review? The contribution of gut microbial signalling to skeletal muscle maintenance and development and identification of potential therapeutic targets in progressive muscle degenerative diseases such as Duchenne muscular dystrophy. What advances does it highlight? Gut microbe-derived metabolites are multifaceted signalling molecules key to muscle function, modifying pathways contributing to skeletal muscle wasting, making them a plausible target for adjunctive therapy in muscular dystrophy. ABSTRACT Skeletal muscle is the largest metabolic organ making up ∼50% of body mass. Because skeletal muscle has both metabolic and endocrine properties, it can manipulate the microbial populations within the gut. In return, microbes exert considerable influence on skeletal muscle via numerous signalling pathways. Gut bacteria produce metabolites (i.e., short chain fatty acids, secondary bile acids and neurotransmitter substrates) that act as fuel sources and modulators of inflammation, influencing host muscle development, growth and maintenance. The reciprocal interactions between microbes, metabolites and muscle establish a bidirectional gut-muscle axis. The muscular dystrophies constitute a broad range of disorders with varying disabilities. In the profoundly debilitating monogenic disorder Duchenne muscular dystrophy (DMD), skeletal muscle undergoes a reduction in muscle regenerative capacity leading to progressive muscle wasting, resulting in fibrotic remodelling and adipose infiltration. The loss of respiratory muscle in DMD culminates in respiratory insufficiency and eventually premature death. The pathways contributing to aberrant muscle remodelling are potentially modulated by gut microbial metabolites, thus making them plausible targets for pre- and probiotic supplementation. Prednisone, the gold standard therapy for DMD, drives gut dysbiosis, inducing a pro-inflammatory phenotype and leaky gut barrier contributing to several of the well-known side effects associated with chronic glucocorticoid treatment. Several studies have observed that gut microbial supplementation or transplantation exerts positive effects on muscle, including mitigating the side effects of prednisone. There is growing evidence in support of the potential for an adjunctive microbiota-directed regimen designed to optimise gut-muscle axis signalling, which could alleviate muscle wasting in DMD.
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Affiliation(s)
- Anthony L. Marullo
- Department of Physiology, School of Medicine, College of Medicine and HealthUniversity College CorkCorkIreland
| | - Ken D. O'Halloran
- Department of Physiology, School of Medicine, College of Medicine and HealthUniversity College CorkCorkIreland
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Leon-Astudillo C, Okorie CUA, McCown MY, Dy FJ, Puranik S, Prero M, ElMallah MK, Treat L, Gross JE. ATS Core Curriculum 2022. Pediatric Pulmonary Medicine: Updates in pediatric neuromuscular disease. Pediatr Pulmonol 2023. [PMID: 37144867 DOI: 10.1002/ppul.26448] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 04/23/2023] [Indexed: 05/06/2023]
Abstract
The American Thoracic Society Core Curriculum updates clinicians annually in pediatric pulmonary disease. This is a concise review of the Pediatric Pulmonary Medicine Core Curriculum presented at the 2022 American Thoracic Society International Conference. Neuromuscular diseases (NMD) comprise a variety of conditions that commonly affect the respiratory system and cause significant morbidity including dysphagia, chronic respiratory failure, and sleep disordered breathing. Respiratory failure is the most common cause of mortality in this population. Substantial progress has been made in diagnosis, monitoring and treatment for NMD over the last decade. Pulmonary function testing (PFT) is utilized to objectively measure respiratory pump function and PFT milestones are utilized in NMD-specific pulmonary care guidelines. New disease modifying therapies are approved for the treatment of patients with Duchenne muscular dystrophy and spinal muscular atrophy (SMA), including the first ever approved systemic gene therapy, in the case of SMA. Despite extraordinary progress in the medical management of NMD, little is known regarding the respiratory implications and long-term outcomes for patients in the era of advanced therapeutics and precision medicine. The combination of technological and biomedical advancements has increased the complexity of the medical decision-making process for patients and families, thus emphasizing the importance of balancing respect for autonomy with the other foundational principles of medical ethics. This review features an overview of PFT, noninvasive ventilation strategies, novel and developing therapies, as well as the ethical considerations specific to the management of patients with pediatric NMD.
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Affiliation(s)
| | - Caroline U A Okorie
- Department of Pediatrics, Stanford Children's Health, Stanford, California, USA
| | - Michael Y McCown
- Department of Pediatrics, Inova Children's Hospital, Fairfax, Virginia, USA
| | - Fei J Dy
- Department of Pediatrics, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA
| | - Sandeep Puranik
- Department of Pediatrics, Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Moshe Prero
- Department of Pediatrics, Rainbow Babies and Children's Hospital, Cleveland, Ohio, USA
| | - Mai K ElMallah
- Department of Pediatrics, Duke University Medical Center, Durham, North Carolina, USA
| | - Lauren Treat
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Jane E Gross
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA
- Departments of Pediatrics and Medicine, National Jewish Health, Denver, Colorado, USA
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Uryash A, Mijares A, Estève E, Adams JA, Lopez JR. Smooth Muscle Cells of Dystrophic (mdx) Mice Are More Susceptible to Hypoxia; The Protective Effect of Reducing Ca 2+ Influx. Biomedicines 2023; 11:biomedicines11020623. [PMID: 36831159 PMCID: PMC9953629 DOI: 10.3390/biomedicines11020623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/13/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is an inherited muscular disorder caused by mutations in the dystrophin gene. DMD patients have hypoxemic events due to sleep-disordered breathing. We reported an anomalous regulation of resting intracellular Ca2+ ([Ca2+]i) in vascular smooth muscle cells (VSMCs) from a mouse (mdx) model of DMD. We investigated the effect of hypoxia on [Ca2+]i in isolated and quiescent VSMCs from C57BL/10SnJ (WT) and C57BL/10ScSn-Dmd (mdx) male mice. [Ca2+]i was measured using Ca2+-selective microelectrodes under normoxic conditions (95% air, 5% CO2) and after hypoxia (glucose-free solution aerated with 95% N2-5% CO2 for 30 min). [Ca2+]i in mdx VSMCs was significantly elevated compared to WT under normoxia. Hypoxia-induced [Ca2+]i overload, which was significantly greater in mdx than in WT VSMCs. A low Ca2+ solution caused a reduction in [Ca2+]i and prevented [Ca2+]i overload secondary to hypoxia. Nifedipine (10 µM), a Ca2+ channel blocker, did not modify resting [Ca2+]i in VSMCs but partially prevented the hypoxia-induced elevation of [Ca2+]i in both genotypes. SAR7334 (1 µM), an antagonist of TRPC3 and TRPC6, reduced the basal and [Ca2+]i overload caused by hypoxia. Cell viability, assessed by tetrazolium salt (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, was significantly reduced in mdx compared to WT VSMCs. Pretreatment with SAR7341 increases cell viability in normoxic mdx (p < 0.001) and during hypoxia in WT and mdx VSMCs. These results provide evidence that the lack of dystrophin makes VSMCs more susceptible to hypoxia-induced [Ca2+]i overload, which appears to be mediated by increased Ca2+ entry through L-type Ca2+ and TRPC channels.
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Affiliation(s)
- Arkady Uryash
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL 33140, USA
| | - Alfredo Mijares
- Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas, Caracas 21827, Venezuela
| | - Eric Estève
- PhyMedExp, University of Montpellier, CNRS, INSERM, CHRU Montpellier, 34090 Montpellier, France
- Univ. Grenoble Alpes, CNRS, TIMC-IMAG/PRETA (UMR 5525), 38000 Grenoble, France
| | - Jose A. Adams
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL 33140, USA
| | - Jose R. Lopez
- Department of Research, Mount Sinai Medical Center, Miami Beach, FL 33140, USA
- Correspondence: ; Tel.: +1-305-674-2727
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Maxwell MN, Marullo AL, Slyne AD, Lucking EF, O'Halloran KD. Ventilatory Effects of Acute Intermittent Hypoxia in Conscious Dystrophic Mice. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1427:83-88. [PMID: 37322338 DOI: 10.1007/978-3-031-32371-3_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Exposure to acute intermittent hypoxia (AIH) elicits a form of respiratory plasticity known as long-term facilitation (LTF). Interest has grown in developing AIH interventions to treat ventilatory insufficiency, with promising results in spinal cord injury and amyotrophic lateral sclerosis. Therapeutic AIH may have application in neuromuscular disorders including muscular dystrophies. We sought to establish hypoxic ventilatory responsiveness and the expression of ventilatory LTF in X-linked muscular dystrophy (mdx) mice.Experiments were performed in 15 male wild-type (BL10) and 15 male mdx mice at 4 months of age. Ventilation was assessed using whole-body plethysmography. Baseline measures of ventilation and metabolism were established. Mice were exposed to 10 successive bouts of hypoxia, each lasting 5 min, interspersed with 5-min bouts of normoxia. Measurements were taken for 60 min following termination of AIH.In mdx mice, ventilation was significantly increased 60 min post-AIH compared to baseline. However, metabolic CO2 production was also increased. Therefore, ventilatory equivalent was unaffected by AIH exposure, i.e., no ventilatory LTF manifestation. In wild-type mice, ventilation and metabolism were not affected by AIH.Eliciting ventilatory LTF is dependent on many factors and may require concomitant isocapnia or hypercapnia during AIH exposures and/or repeated daily AIH exposures, which is worthy of further pursuit.
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Affiliation(s)
- Michael N Maxwell
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Anthony L Marullo
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Aoife D Slyne
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Eric F Lucking
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
| | - Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland.
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O'Halloran KD. Breathing new life into therapies for Duchenne muscular dystrophy. J Physiol 2022; 600:3453-3454. [PMID: 35908978 DOI: 10.1113/jp283343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Accepted: 06/21/2022] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ken D O'Halloran
- Department of Physiology, School of Medicine, College of Medicine & Health, University College Cork, Cork, Ireland
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