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Metabolic Alterations in Cardiomyocytes of Patients with Duchenne and Becker Muscular Dystrophies.

ABSTRACT: Duchenne and Becker muscular dystrophies (DMD/BMD) result in progressive weakness of skeletal and cardiac muscles due to the deficiency of functional dystrophin. Respiratory failure is a leading cause of mortality in DMD patients; however, improved management of the respiratory symptoms have increased patients' life expectancy, thereby also increasing the clinical relevance of heart disease. In fact, the prevalence of cardiomyopathy, which significantly contributes to mortality in DMD patients, increases with age and disease progression, so that over 95% of adult patients has cardiomyopathy signs. We here review the current literature featuring the metabolic alterations observed in the dystrophic heart of the mdx mouse, i.e., the best-studied animal model of the disease, and discuss their pathophysiological role in the DMD heart. It is well assessed that dystrophin deficiency is associated with pathological alterations of lipid metabolism, intracellular calcium levels, neuronal nitric oxide (NO) synthase localization, and NO and reactive oxygen species production. These metabolic stressors contribute to impair the function of the cardiac mitochondrial bulk, which has a relevant pathophysiological role in the development of cardiomyopathy. In fact, mitochondrial dysfunction becomes more severe as the dystrophic process progresses, thereby indicating it may be both the cause and the consequence of the dystrophic process in the DMD heart.

SUBMITTER: Esposito G

PROVIDER: S-EPMC6947625 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature

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Metabolic Alterations in Cardiomyocytes of Patients with Duchenne and Becker Muscular Dystrophies.

Esposito Gabriella G Carsana Antonella A

Journal of clinical medicine 20191205 12

Duchenne and Becker muscular dystrophies (DMD/BMD) result in progressive weakness of skeletal and cardiac muscles due to the deficiency of functional dystrophin. Respiratory failure is a leading cause of mortality in DMD patients; however, improved management of the respiratory symptoms have increased patients' life expectancy, thereby also increasing the clinical relevance of heart disease. In fact, the prevalence of cardiomyopathy, which significantly contributes to mortality in DMD patients, ...[more]

PMID: 31817415

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Project description:BACKGROUND:Analysis of muscle biopsies allowed to characterize the pathophysiological changes of Duchenne and Becker muscular dystrophies (D/BMD) leading to the clinical phenotype. Muscle tissue is often investigated during interventional dose finding studies to show in situ proof of concept and pharmacodynamics effect of the tested drug. Less invasive readouts are needed to objectively monitor patients' health status, muscle quality, and response to treatment. The identification of serum biomarkers correlating with clinical function and able to anticipate functional scales is particularly needed for personalized patient management and to support drug development programs. METHODS:A large-scale proteomic approach was used to identify serum biomarkers describing pathophysiological changes (e.g. loss of muscle mass), association with clinical function, prediction of disease milestones, association with in vivo 31 P magnetic resonance spectroscopy data and dystrophin levels in muscles. Cross-sectional comparisons were performed to compare DMD patients, BMD patients, and healthy controls. A group of DMD patients was followed up for a median of 4.4 years to allow monitoring of individual disease trajectories based on yearly visits. RESULTS:Cross-sectional comparison enabled to identify 10 proteins discriminating between healthy controls, DMD and BMD patients. Several proteins (285) were able to separate DMD from healthy, while 121 proteins differentiated between BMD and DMD; only 13 proteins separated BMD and healthy individuals. The concentration of specific proteins in serum was significantly associated with patients' performance (e.g. BMP6 serum levels and elbow flexion) or dystrophin levels (e.g. TIMP2) in BMD patients. Analysis of longitudinal trajectories allowed to identify 427 proteins affected over time indicating loss of muscle mass, replacement of muscle by adipose tissue, and cardiac involvement. Over-representation analysis of longitudinal data allowed to highlight proteins that could be used as pharmacodynamic biomarkers for drugs currently in clinical development. CONCLUSIONS:Serum proteomic analysis allowed to not only discriminate among DMD, BMD, and healthy subjects, but it enabled to detect significant associations with clinical function, dystrophin levels, and disease progression.

Project description:Heart impairment is classical in dystrophinopathies and its management relies on medical drugs. Mechanical ventilation is used to treat respiratory failure, but can affect cardiac function. We aimed to investigate the natural history of cardiac function in patients with Duchenne (DMD) and Becker (BMD) muscular dystrophies on home mechanical ventilation (HMV).We reviewed the chart of DMD and BMD patients, followed in our institution, to obtain ventilation setting at HMV initiation and echocardiographic data at baseline and end follow up, as well as onset cardiac events and thoracic mechanical complication. We analyzed cumulative incidence of cardiac events as well as echocardiographic parameters evolution and its association with ventilation settings.We included 111 patients (101 DMD and 10 BMD). Median age was 21 years [18-26], median pulmonary vital capacity (VC) 15% of predicted [10-24]. All patients were on HMV and 46% ventilated using tracheostomy. After a median follow up of 6.3 years, we found a slight decrease of the left ventricular ejection fraction (LVEF) (45% at end follow up vs 50% at baseline P?=?.019) and a stabilization of the LV end diastolic diameter indexed (LVEDD indexed 29.4?mm/m vs 30.7?mm/m at end follow up, P?=?.17). Tidal volume (VT) level was inversely associated with the annual rate of the LVEF decline (r?=?-0.29, P?=?.025). Left atrium (LA) diameter decreased with mechanical ventilation (24?mm vs 20?mm, P?=?.039) and we found a reduction of systolic pulmonary pressure (35?mm Hg vs 25?mm Hg, P?=?.011). The cumulative incidence of cardiac events was 12.6%. Pneumothorax occurred in 4% of patients. Hypoxic arrest secondary to the presence of tracheal plugin occurred in 4% of patients with invasive ventilation.HMV is not harmful, decreases pulmonary pressure and may protect heart in dystrophinopathies, in addition with cardioprotective drugs. In patients with DMD and BMD on HMV, cumulative incidence of cardiac events remains moderate and incidence of pneumothorax is rare.

Project description:IntroductionPrevious studies indicated variability in the prevalence of Duchenne and Becker muscular dystrophies (DBMD) by racial/ethnic groups. The Centers for Disease Control and Prevention's (CDC) Muscular Dystrophy Surveillance, Tracking, and Research network (MD STARnet) conducts muscular dystrophy surveillance in multiple geographic areas of the USA and continues to enroll new cases. This provides an opportunity to continue investigating differences in DBMD prevalence by race and ethnicity and to compare the impact of using varying approaches for estimating prevalence.ObjectiveTo estimate overall and race/ethnicity-specific prevalence of DBMD among males aged 5-9 years and compare the performance of three prevalence estimation methods.MethodsThe overall and race/ethnicity-specific 5-year period prevalence rates were estimated with MD STARnet data using three methods. Method 1 used the median of 5-year prevalence, and methods 2 and 3 calculated prevalence directly with different birth cohorts. To compare prevalence between racial/ethnic groups, Poisson modeling was used to estimate prevalence ratios (PRs) with non-Hispanic (NH) whites as the referent group. Comparison between methods was also conducted.ResultsIn the final population-based sample of 1,164 DBMD males, the overall 5-year prevalence for DBMD among 5-9 years of age ranged from 1.92 to 2.48 per 10,000 males, 0.74-1.26 for NH blacks, 1.78-2.26 for NH whites, 2.24-4.02 for Hispanics, and 0.61-1.83 for NH American Indian or Alaska Native and Asian or Native Hawaiian or Pacific Islander (AIAN/API). The PRs for NH blacks/NH whites, Hispanics/NH whites, and NH AIAN/API/NH whites were 0.46 (95% CI: 0.36-0.59), 1.37 (1.17-1.61), and 0.61 (0.40-0.93), respectively.ConclusionsIn males aged 5-9 years, compared to the prevalence of DBMD in NH whites, prevalence in NH blacks and NH AIAN/API was lower and higher in Hispanics. All methods produced similar prevalence estimates; however, method 1 produced narrower confidence intervals and method 2 produced fewer zero prevalence estimates than the other two methods.

Project description:BackgroundDuchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are characterized by muscle wasting leading to loss of ambulation in the first or third decade, respectively. In DMD, the lack of dystrophin hampers connections between intracellular cytoskeleton and cell membrane leading to repeated cycles of necrosis and regeneration associated with inflammation and loss of muscle ordered structure. BMD has a similar muscle phenotype but milder. Here, we address the question whether proteins at variance in BMD compared with DMD contribute to the milder phenotype in BMD, thus identifying a specific signature to be targeted for DMD treatment.MethodsProteins extracted from skeletal muscle from DMD/BMD patients and young healthy subjects were either reduced and solubilized prior two-dimensional difference in gel electrophoresis/mass spectrometry differential analysis or tryptic digested prior label-free liquid chromatography with tandem mass spectrometry. Statistical analyses of proteins and peptides were performed by DeCyder and Perseus software and protein validation and verification by immunoblotting.ResultsProteomic results indicate minor changes in the extracellular matrix (ECM) protein composition in BMD muscles with retention of mechanotransduction signalling, reduced changes in cytoskeletal and contractile proteins. Conversely, in DMD patients, increased levels of several ECM cytoskeletal and contractile proteins were observed whereas some proteins of fast fibres and of Z-disc decreased. Detyrosinated alpha-tubulin was unchanged in BMD and increased in DMD although neuronal nitric oxide synthase was unchanged in BMD and greatly reduced in DMD. Metabolically, the tissue is characterized by a decrement of anaerobic metabolism both in DMD and BMD compared with controls, with increased levels of the glycogen metabolic pathway in BMD. Oxidative metabolism is severely compromised in DMD with impairment of malate shuttle; conversely, it is active in BMD supporting the tricarboxylic acid cycle and respiratory chain. Adipogenesis characterizes DMD, whereas proteins involved in fatty acids beta-oxidation are increased in BMD. Proteins involved in protein/amino acid metabolism, cell development, calcium handling, endoplasmic reticulum/sarcoplasmic reticulum stress response, and inflammation/immune response were increased in DMD. Both disorders are characterized by the impairment of N-linked protein glycosylation in the endoplasmic reticulum. Authophagy was decreased in DMD whereas it was retained in BMD.ConclusionsThe mechanosensing and metabolic disruption are central nodes of DMD/BMD phenotypes. The ECM proteome composition and the metabolic rewiring in BMD lead to preservation of energy levels supporting autophagy and cell renewal, thus promoting the retention of muscle function. Conversely, DMD patients are characterized by extracellular and cytoskeletal protein dysregulation and by metabolic restriction at the level of ?-ketoglutarate leading to shortage of glutamate-derived molecules that over time triggers lipogenesis and lipotoxicity.

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Metabolic Alterations in Cardiomyocytes of Patients with Duchenne and Becker Muscular Dystrophies.

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Metabolic Alterations in Cardiomyocytes of Patients with Duchenne and Becker Muscular Dystrophies.

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