The Effect of Adiposity on Cardiovascular Function and Myocardial Fibrosis in Patients With Duchenne Muscular Dystrophy

Obesity Management in Youth with Duchenne Muscular Dystrophy: A Review of Metformin and Alternative Pharmacotherapies

Background: Individuals with Duchenne muscular dystrophy (DMD) have increased risk of obesity from prolonged glucocorticoid use and progressive muscle weakness. Over 50% have obesity by the teenage years. Objectives: The current study examines literature on obesity management in DMD and describes how obesity pharmacotherapy can be used in this high-risk cohort. Methods: This review was conducted in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist. A Pubmed Database search was conducted from January 2000 to May 2024. Included terms were DMD and topiramate, phentermine, metformin, glucagon-like peptide-1 receptor agonist, semaglutide, and liraglutide. Eligible studies were cataloged to examine obesity pharmacotherapy, side effect profiles, and clinical outcomes. Results: Twenty studies met inclusion criteria, 18 on metformin. Reviewed studies varied in duration from 4 to 24 weeks, ages 6.5-44 years old, with 112 participants total (range: 1-30 participants). Included studies were: eight animal studies, six clinical trials, four reviews, one cohort study, and one case report. Primary outcomes varied among studies: muscular degeneration and function (15 articles), cardiac function (2 articles), weight loss (2 articles), and general endocrine care (1 article). Conclusions: Adjunct obesity pharmacotherapy use in youth with DMD is promising but needs to be confirmed. Large gaps include appropriate agent selection, side effect monitoring, and dose escalation. The overall quality of pediatric-specific evidence for the use of obesity pharmacotherapy in youth with DMD is low. Future research is needed to investigate how to safely utilize these agents.

Electrophysiologic and cardiovascular manifestations of Duchenne and Becker muscular dystrophies

There have been significant advances in the diagnosis and management of the hereditary muscular disorders Duchenne and Becker muscular dystrophy (DMD and BMD). Cardiac electrophysiologic and cardiovascular involvement has long been important in the surveillance, care, and prognosis of patients with both BMD and DMD and is the leading cause of mortality in patients with DMD. With improved long-term prognosis, rhythm disorders and progressive cardiomyopathy with resultant heart failure are increasingly common. This review aimed to provide an overview to electrophysiologists and cardiologists of the cardiac electrophysiologic phenotypes and genetics of BMD and DMD and to highlight the recent discoveries that have advanced clinical course and management. A systematic review was performed of the diagnosis and management of DMD and BMD. The Cochrane Library, PubMed, MEDLINE, Europe PubMed Central, AMED, and Embase databases were accessed for available evidence. The research reported in this paper adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Evidence from randomized controlled trials and studies cited in expert consensus and practice guidelines are examined. Advanced imaging techniques and a spectrum of rhythm disorders associated with the progressive cardiomyopathy are presented. Early initiation of heart failure therapies, the role of cardiac implantable devices, and novel gene therapies approved for use with the potential to alter the disease course are discussed. When profound cardiac and cardiac electrophysiologic involvement is diagnosed and treated earlier, outcomes for DMD and BMD patients may be improved.

Fibro-adipogenic progenitors in physiological adipogenesis and intermuscular adipose tissue remodeling

Excessive accumulation of intermuscular adipose tissue (IMAT) is a common pathological feature in various metabolic and health conditions and can cause muscle atrophy, reduced function, inflammation, insulin resistance, cardiovascular issues, and unhealthy aging. Although IMAT results from fat accumulation in muscle, the mechanisms underlying its onset, development, cellular components, and functions remain unclear. IMAT levels are influenced by several factors, such as changes in the tissue environment, muscle type and origin, extent and duration of trauma, and persistent activation of fibro-adipogenic progenitors (FAPs). FAPs are a diverse and transcriptionally heterogeneous population of stromal cells essential for tissue maintenance, neuromuscular stability, and tissue regeneration. However, in cases of chronic inflammation and pathological conditions, FAPs expand and differentiate into adipocytes, resulting in the development of abnormal and ectopic IMAT. This review discusses the role of FAPs in adipogenesis and how they remodel IMAT. It highlights evidence supporting FAPs and FAP-derived adipocytes as constituents of IMAT, emphasizing their significance in adipose tissue maintenance and development, as well as their involvement in metabolic disorders, chronic pathologies and diseases. We also investigated the intricate molecular pathways and cell interactions governing FAP behavior, adipogenesis, and IMAT accumulation in chronic diseases and muscle deconditioning. Finally, we hypothesize that impaired cellular metabolic flexibility in dysfunctional muscles impacts FAPs, leading to IMAT. A deeper understanding of the biology of IMAT accumulation and the mechanisms regulating FAP behavior and fate are essential for the development of new therapeutic strategies for several debilitating conditions.

Left ventricular concentric hypertrophy with cardiac magnetic resonance imaging improves risk stratification in patients with Duchenne muscular dystrophy: a prospective cohort study

BACKGROUND

The development of left ventricular (LV) remodeling has been associated with an increased cardiovascular risk and cardiogenic death, and different patterns of remodeling result in varying levels of prognosis.

OBJECTIVE

To investigate the association between different patterns of LV remodeling and clinical outcomes in the preclinical stage of patients with Duchenne muscular dystrophy (DMD).

MATERIALS AND METHODS

A total of 148 patients with DMD and 43 sex- and age-matched healthy participants were enrolled. We used the four-quadrant analysis method to investigate LV remodeling based on cardiac magnetic resonance (MR) imaging. Kaplan-Meier curves were generated to illustrate the event-free survival probability stratified by the LV remodeling pattern. Cox regression models were constructed and compared to evaluate the incremental predictive value of the LV remodeling pattern.

RESULTS

During the median follow-up period of 2.2 years, all-cause death, cardiomyopathy, and ventricular arrhythmia occurred in 5, 35, and 7 patients, respectively. LV concentric hypertrophy (hazard ratio 2.91, 95% confidence interval 1.47-5.75, P=0.002) was an independent predictor of composite endpoint events. Compared to the model without LV concentric hypertrophy, the model with LV concentric hypertrophy had significant incremental predictive value (chi-square value 33.5 vs. 25.2, P=0.004).

CONCLUSION

Age and late gadolinium enhancement positivity were positively correlated with clinical outcomes according to the prediction models. LV concentric hypertrophy was also an independent predictor for risk stratification and provided incremental value for predicting clinical outcomes in the preclinical stage of patients with DMD.

Association of increased epicardial adipose tissue derived from cardiac magnetic resonance imaging with myocardial fibrosis in Duchenne muscular dystrophy: a clinical prediction model development and validation study in 283 participants

Background

Epicardial adipose tissue (EAT) contributes to inflammation and fibrosis of the neighboring myocardial tissue via paracrine signaling. In this retrospective study, we investigated the abnormal changes in the amount of EAT in male children with Duchenne muscular dystrophy (DMD) using cardiac magnetic resonance (CMR) imaging. Furthermore, we constructed and validated a nomogram including EAT-related CMR imaging parameter for predicting the occurrence of myocardial fibrosis in patients with DMD.

Methods

This study enrolled 283 patients with DMD and 57 healthy participants who underwent CMR acquisitions to measure the quantitative parameters of EAT, pericardial adipose tissue (PAT), paracardial adipose tissue, and subcutaneous adipose tissue. Late gadolinium enhancement (LGE) was performed to confirm myocardial fibrosis in patients with DMD. The DMD group consisted of 200 patients from institution 1 (the ratio of the training set and the internal validation set was 7:3) and 83 patients from four other institutions (the external validation set). Logistic and least absolute shrinkage and selection operator (LASSO) regression was used to select the optimal predictors and to develop and validate the nomogram model predicting LGE risk in the training set, internal validation set, and external validation set.

Results

Compared with those in healthy controls, some regional EAT thicknesses, areas, and global volumes were significantly higher in patients with DMD, and 41.7% of patients with DMD showed positive LGE. These LGE-positive patients with DMD showed significantly higher EAT volume (median 23.9 mL/m3; P<0.001) and PAT volume (median 31.8 mL/m3; P<0.001) compared with the LGE-negative patients with DMD. Age [odds ratio (OR) 2.0; P<0.001], body fat percentage (OR 1.3; P<0.001), and EAT volume (OR 1.4; P<0.001) were independently associated with positive LGE in the training set. The interactive dynamic nomogram showed superior prediction performance, with a high degree of the calibration, discrimination, and clinical net benefit in the training and validation of the DMD datasets. The area under the curve (AUC) values of the nomogram in the training set, internal validation set, and external validation set were 0.95 [95% confidence interval (CI): 0.91-0.98], 0.97 (95% CI: 0.92-0.99), and 0.95 (95% CI: 0.91-0.99), respectively.

Conclusions

The onset of LGE-based myocardial fibrosis was associated with EAT volume in patients with DMD. Additionally, the nomogram with EAT volumes showed superior performance in patients with DMD for predicting the occurrence of myocardial fibrosis.

Histological and Histochemical Microscopy Used to Verify 2D-DIGE Pathoproteomics

Comparative gel electrophoretic analyses of normal versus pathological specimens can swiftly identify proteome-wide changes in the concentration of specific protein isoforms. The application of fluorescence two-dimensional difference gel electrophoresis (2D-DIGE) can be employed for the characterization of complex protein populations in health and disease. In order to verify pathoproteomic findings and correlate them to histopathological alterations, standardized histological and histochemical methodology can be applied for the cell biological analysis of normal versus pathological tissue samples. This chapter outlines the usage of histochemical ATPase staining of fast and slow fiber types in normal versus dystrophic skeletal muscles, as well as the application of hematoxylin and eosin staining of nuclei and the cellular body in kidney cells, and Sudan black staining of lipids in cryo-sections.

Obesity and loss of ambulation are associated with lower extremity oedema in Duchenne muscular dystrophy

Patients with Duchenne muscular dystrophy have multiple risk factors for lower extremity oedema. This study sought to define the frequency and predictors of oedema. Patients aged 15 years and older were screened by patient questionnaire, and the presence of oedema was confirmed by subsequent physical exam. Twenty-four of 52 patients (46%) had oedema, 12 of whom had swelling extending above the foot and two with sores/skin breakdown. There was no significant difference in age, frequency, or duration of glucocorticoid use, non-invasive respiratory support use, forced vital capacity, cardiac medication use, or ejection fraction between patients with and without oedema (all p > 0.2). Those with oedema had a greater time since the loss of ambulation (8.4 years versus 3.5 years; p = 0.004), higher body mass index (28.3 versus 24.8; p = 0.014), and lower frequency of deflazacort use (67% versus 89%; p = 0.008). Multivariate analysis revealed a longer duration of loss of ambulation (p = 0.02) and higher body mass index (p = 0.009) as predictors of oedema. Lower extremity oedema is common in Duchenne muscular dystrophy but independent of cardiac function. Interventions focused on minimising body mass index increases over time may be a therapeutic target.