Paradoxical weight loss with extra energy expenditure at brown adipose tissue in adolescent patients with Duchenne muscular dystrophy

Effect of nutritional therapy in Emery-Dreifuss muscular dystrophy: a case report

Emery-Dreifuss muscular dystrophy (EDMD) is a rare, inherited human disease. Similar to other neuromuscular dystrophies, EDMD is clinically characterized by muscle atrophy and weakness, multi-joint contractures with spine rigidity, and cardiomyopathy. Over time, muscular weakness can lead to dysphagia and a severe lowering of body mass index (BMI), worsening the prognosis. We present the case of a young male patient affected by EDMD, admitted to the hospital for pneumothorax in a severe state of undernourishment. The patient was treated with total parenteral nutrition (TPN) with Smofkabiven®, supplemented with micronutrients (vitamins and trace elements), and with minimal enteral nutrition through food. Within a year, the patient gained 8.5 kg and kept his body weight stable for the 6 years of the follow-up. In this study, we show that TPN ensures the nutritional requirements of EDMD patients in a safe and well-tolerated manner, allowing a considerable and stable improvement in nutritional status, which has a positive impact on the disease itself and the patients' quality of life.

Humanization of the mdx Mouse Phenotype for Duchenne Muscular Dystrophy Modeling: A Metabolic Perspective

Duchenne muscular dystrophy (DMD) is a severe form of muscular dystrophy (MD) that is characterized by early muscle wasting and lethal cardiorespiratory failure. While the mdx mouse is the most common model of DMD, it fails to replicate the severe loss of muscle mass and other complications observed in patients, in part due to the multiple rescue pathways found in mice. This led to several attempts at improving DMD animal models by interfering with these rescue pathways through double transgenic approaches, resulting in more severe phenotypes with mixed relevance to the human pathology. As a growing body of literature depicts DMD as a multi-system metabolic disease, improvements in mdx-based modeling of DMD may be achieved by modulating whole-body metabolism instead of muscle homeostasis. This review provides an overview of the established dual-transgenic approaches that exacerbate the mild mdx phenotype by primarily interfering with muscle homeostasis and highlights how advances in DMD modeling coincide with inducing whole-body metabolic changes. We focus on the DBA2/J strain-based D2.mdx mouse with heightened transforming growth factor (TGF)-β signaling and the dyslipidemic mdx/apolipoprotein E (mdx/ApoE) knock-out (KO) mouse, and summarize how these novel models emulate the metabolic changes observed in DMD.

Metabolomic Analyses Reveal Extensive Progenitor Cell Deficiencies in a Mouse Model of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a musculoskeletal disorder that causes severe morbidity and reduced lifespan. Individuals with DMD have an X-linked mutation that impairs their ability to produce functional dystrophin protein in muscle. No cure exists for this disease and the few therapies that are available do not dramatically delay disease progression. Thus, there is a need to better understand the mechanisms underlying DMD which may ultimately lead to improved treatment options. The muscular dystrophy (MDX) mouse model is frequently used to explore DMD disease traits. Though some studies of metabolism in dystrophic mice exist, few have characterized metabolic profiles of supporting cells in the diseased environment. Using nontargeted metabolomics we characterized metabolic alterations in muscle satellite cells (SCs) and serum of MDX mice. Additionally, live-cell imaging revealed MDX-derived adipose progenitor cell (APC) defects. Finally, metabolomic studies revealed a striking elevation of acylcarnitines in MDX APCs, which we show can inhibit APC proliferation. Together, these studies highlight widespread metabolic alterations in multiple progenitor cell types and serum from MDX mice and implicate dystrophy-associated metabolite imbalances in APCs as a potential contributor to adipose tissue disequilibrium in DMD.

Noncoding Transcriptional Landscape in Human Aging

Aging is a universal phenomenon in metazoans, characterized by a general decline of the organism physiology associated with an increased risk of mortality and morbidity. Aging of an organism correlates with a decline in function of its cells, as shown for muscle, immune, and neuronal cells. As the DNA content of most cells within an organism remains largely identical throughout the life span, age-associated transcriptional changes must be achieved by epigenetic mechanisms. However, how aging may impact on the epigenetic state of cells is only beginning to be understood. In light of a growing number of studies demonstrating that noncoding RNAs can provide molecular signals that regulate expression of protein-coding genes and define epigenetic states of cells, we hypothesize that noncoding RNAs could play a direct role in inducing age-associated profiles of gene expression. In this context, the role of long noncoding RNAs (lncRNAs) as regulators of gene expression might be important for the overall transcriptional landscape observed in aged human cells. The possible functions of lncRNAs and other noncoding RNAs, and their roles in the regulation of aging-related cellular pathways will be analyzed.

Hexose enhances oligonucleotide delivery and exon skipping in dystrophin-deficient mdx mice

Carbohydrate-based infusion solutions are widely used in the clinic. Here we show that co-administration of phosphorodiamidate morpholino oligomers (PMOs) with glucose enhances exon-skipping activity in Duchenne muscular dystrophy (DMD) mdx mice. We identify a glucose-fructose (GF) formulation that potentiates PMO activity, completely corrects aberrant Dmd transcripts, restores dystrophin levels in skeletal muscles and achieves functional rescue without detectable toxicity. This activity is attributed to enhancement of GF-mediated PMO uptake in the muscle. We demonstrate that PMO cellular uptake is energy dependent, and that ATP from GF metabolism contributes to enhanced cellular uptake of PMO in the muscle. Collectively, we show that GF potentiates PMO activity by replenishing cellular energy stores under energy-deficient conditions in mdx mice. Our findings provide mechanistic insight into hexose-mediated oligonucleotide delivery and have important implications for the development of DMD exon-skipping therapy.

Decreased resting energy expenditure in patients with Duchenne muscular dystrophy

BACKGROUND

Skeletal muscle metabolism is a major determinant of resting energy expenditure (REE). Although the severe muscle loss that characterizes Duchenne muscular dystrophy (DMD) may alter REE, this has not been extensively investigated.

METHODS

We studied REE in 77 patients with DMD ranging in age from 10 to 37 years using a portable indirect calorimeter, together with several clinical parameters (age, height, body weight (BW), body mass index (BMI), vital capacity (VC), creatine kinase, creatinine, albumin, cholinesterase, prealbumin), and assessed their influence on REE. In addition, in 12 patients maintaining a stable body weight, the ratio of energy intake to REE was calculated and defined as an alternative index for the physical activity level (aPAL).

RESULTS

REE (kcal/day, mean±SD) in DMD patients was 1123 (10-11 years), 1186±188 (12-14 years), 1146±214 (15-17 years), 1006±136 (18-29 years) and 1023±97 (≥30 years), each of these values being significantly lower than the corresponding control (p<0.0001). VC (p<0.001) was the parameter most strongly associated with REE, followed by BMI (p<0.01) and BW (p<0.05). The calculated aPAL values were 1.61 (10-11 years), 1.19 (12-14 years), 1.16 (15-17 years), and 1.57 (18-29 years).

CONCLUSION

The REE in DMD patients was significantly lower than the normal value in every age group, and strongly associated with VC. Both the low REE and PAL values during the early teens, resulting in a low energy requirement, might be related to the obesity that frequently occurs in this age group. In contrast, the high PAL value in the late stage of the disease, possibly due to the presence of respiratory failure, may lead to a high energy requirement, and thus become one of the risk factors for development of malnutrition.

Correlação da massa e porcentagem de gordura com a idade na distrofia muscular de Duchenne

INTRODUÇÃO: A Distrofia Muscular de Duchenne (DMD) é uma desordem genética, caracterizada pela perda progressiva e irreversível da musculatura esquelética. OBJETIVO: Este estudo objetiva correlacionar a porcentagem e a massa de gordura com a idade em pacientes com DMD. METODOLOGIA: Foram selecionados 68 indivíduos com idades entre 5 e 20 anos, com diagnóstico molecular de certeza para DMD, residentes na cidade de São Paulo. Todos foram submetidos à mensuração do peso e altura e também ao teste de análise de composição corporal com o uso da bioimpedância, no período da manhã, todas no mesmo dia. RESULTADOS E DISCUSSÃO: Os resultados foram analisados agrupando os indivíduos em quartis de idade e mostraram um índice de massa corpóreo (IMC) de 21 ± 8 kg/m². Assim, observou-se que, com a idade e o grau de sedentarismo imposto pela doença, houve um acúmulo de gordura corporal e perda de massa magra. CONCLUSÃO: São necessários mais estudos relacionados às características nutricionais desses indivíduos, para que se esclareçam melhor os efeitos da doença e da alimentação no ganho de porcentagem e massa de gordura.

Blastocyst injection of wild type embryonic stem cells induces global corrections in mdx mice

Duchenne muscular dystrophy (DMD) is an incurable neuromuscular degenerative disease, caused by a mutation in the dystrophin gene. Mdx mice recapitulate DMD features. Here we show that injection of wild-type (WT) embryonic stem cells (ESCs) into mdx blastocysts produces mice with improved pathology and function. A small fraction of WT ESCs incorporates into the mdx mouse nonuniformly to upregulate protein levels of dystrophin in the skeletal muscle. The chimeric muscle shows reduced regeneration and restores dystrobrevin, a dystrophin-related protein, in areas with high and with low dystrophin content. WT ESC injection increases the amount of fat in the chimeras to reach WT levels. ESC injection without dystrophin does not prevent the appearance of phenotypes in the skeletal muscle or in the fat. Thus, dystrophin supplied by the ESCs reverses disease in mdx mice globally in a dose-dependent manner.

Increased resting energy expenditure in subjects with Emery-Dreifuss muscular dystrophy

We have studied changes in energy expenditure and body composition in adult males with Emery-Dreifuss muscular dystrophy, age-matched males with hyperCKemia and age-matched healthy controls. All participants were studied twice, 2-3 years apart. Resting energy expenditure was studied by indirect calorimetry, lean body mass and body fat by dual X-ray absorptiometry, and muscle mass was estimated based on 24-h urinary creatinine excretion. At baseline and 2-3 years later, body fat was significantly higher (P < 0.011 and P < 0.003, respectively) and lean body mass significantly lower (P < 0.024 and P < 0.012, respectively) in patients with Emery-Dreifuss muscular dystrophy as compared to subjects with hyperCKemia and healthy controls. Resting energy expenditure, over the study period, increased significantly in patients with Emery-Dreifuss muscular dystrophy (P < 0.031), but not in patients with hyperCKemia nor in healthy controls. Our study suggests that patients with Emery-Dreifuss muscular dystrophy may have increased energy expenditure relative to healthy subjects. If not met by increased caloric intake, this greater energy expenditure may partially contribute to a further deterioration in their muscle performance.