Duchenne and Becker muscular dystrophy in adolescents: current perspectives

The challenges faced by patients with hereditary myopathy during the COVID-19 pandemic

BACKGROUND

Neuromuscular diseases are inherited and the prevalance of neuromuscular disease is estimated to be around 1:2000.

METHODS

This cross-sectional research was conducted with a qualitative research model. Data were collected from patients with an online survey using the snowball sampling method. The study was conducted in accordance with the STROBE checklist methodology. Frequencies and percentages were used to analyse demographic data, and content analysis was used for qualitative opinions.

RESULTS

Most of the participants were men and their education levels were low. Participants reported experiencing physical and socio-economic barriers to accessing healthcare. Participants also stated that these barriers have worsened since COVID-19.

CONCLUSIONS

Patients with hereditary myopathy are stigmatised by society and face different problems depending on the type of disease and level of function. It is recommended that decision-makers enable patients with hereditary myopathy in exceptional situations to access healthcare services and take steps to resolve their problems.

Mutation spectrum analysis of DMD gene in Indonesian Duchenne and Becker muscular dystrophy patients

Background

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are allelic disorders caused by mutations in the DMD gene. The full mutation spectrum of the DMD gene in Indonesian patients is currently unknown. Mutation-specific therapies are currently being developed, such as exon skipping or stop codon read-through therapy. This study was conducted with the aim of identifying the mutation spectrum of the DMD gene in Indonesia to guide future development and application of feasible therapeutic strategies.

Methods

This study is a cross sectional study that enrolled 43 male patients with a clinical suspicion of DMD or BMD. Multiplex ligation-dependent probe amplification (MLPA) reaction was performed to screen for the common mutations in the DMD gene.

Results

Out of 43 subjects, deletions accounted for 69.77% (n=30) cases, while duplications were found in 11.63% (n=5) cases. One novel duplication spanning exons 2 to 62 was identified. Deletion mutations clustered around the distal (66.67%) and proximal (26.67%) hot spot regions of the DMD gene while duplication mutations were observed solely at the proximal region. Two false positive cases of single exon deletion detected through MLPA were attributed to sequence mutations affecting primer ligation sites, confirming the need to validate all single exon deletions when using this screening method. Analysis of available maternal DNA samples showed that the rate of de novo mutations (48.15%) appears higher than expected in this population. Out of 31 patients who were classified as DMD based on clinical and genotype characterizations, 60.47% (n=26) of cases were suitable for exon skipping therapy.

Conclusion

This is the first comprehensive study showing the feasibility of implementing the MLPA method for routine screening of DMD patients in Indonesia. This is also the first study showing the potential applicability of exon skipping therapy in the majority of DMD cases in the country.

End of Life in Boys and Young Men With Duchenne Muscular Dystrophy - The Perspective of Dying Men and Their Families: A Systematic Review and Thematic Synthesis of Qualitative Evidence

Understanding the perceptions and experiences related to the end of life (EoL) of boys and men with Duchenne muscular dystrophy from their own and/or family perspective is limited based on the available qualitative empirical studies. This systematic review was done with a thematic synthesis of qualitative evidence according to the PRISMA Statement Guidelines and the SPIDER search tool. The review included empirical, qualitative, and relevant full-text studies published in 2000-2023 in the EBSCO Discovery Service, ISI Web of Science, Scopus, PubMed, and ProQuest databases. From o total of eight included qualitative studies, four main key themes were identified: "Being a parent/caregiver" - psychosocial aspects, needs, and experiences; "Communication about EoL with healthcare and other professionals" - positive experiences and personal shortcomings; "Discussions about…" - the issue of EoL, dying and death; and "End of life" - end-of-life care, planning and the need for palliative care.

Perks of Rehabilitation in Improving Motor Function in a Nine-Year-Old Male With Duchenne Muscular Dystrophy: A Case Report

Duchenne muscular dystrophy (DMD) is a progressive disorder. It is the most typical X-linked muscular dystrophy in children. It primarily affects males and is characterized by motor delays, muscle weakness, respiratory impairment, and loss of ambulation. A case study of a nine-year-old male diagnosed with DMD is presented. The patient had difficulty walking since the age of four and had a proximal lower extremity weakness on both sides previously with a reduced range of motion (ROM). For the last 15 days, the patient is unable to walk and has hypotonia in both lower limbs. The diagnostic Gowers sign was positive. Balance and mobility were affected. Treatment of this patient is focused mostly on maintaining the range of motion (ROM), respiratory training, and balance.

CRISPR-Based Therapeutic Gene Editing for Duchenne Muscular Dystrophy: Advances, Challenges and Perspectives

Duchenne muscular dystrophy (DMD) is a severe neuromuscular disease arising from loss-of-function mutations in the dystrophin gene and characterized by progressive muscle degeneration, respiratory insufficiency, cardiac failure, and premature death by the age of thirty. Albeit DMD is one of the most common types of fatal genetic diseases, there is no curative treatment for this devastating disorder. In recent years, gene editing via the clustered regularly interspaced short palindromic repeats (CRISPR) system has paved a new path toward correcting pathological mutations at the genetic source, thus enabling the permanent restoration of dystrophin expression and function throughout the musculature. To date, the therapeutic benefits of CRISPR genome-editing systems have been successfully demonstrated in human cells, rodents, canines, and piglets with diverse DMD mutations. Nevertheless, there remain some nonignorable challenges to be solved before the clinical application of CRISPR-based gene therapy. Herein, we provide an overview of therapeutic CRISPR genome-editing systems, summarize recent advancements in their applications in DMD contexts, and discuss several potential obstacles lying ahead of clinical translation.

Baseline fat fraction is a strong predictor of disease progression in Becker muscular dystrophy

In Becker muscular dystrophy (BMD), muscle weakness progresses relatively slowly, with a highly variable rate among patients. This complicates clinical trials, as clinically relevant changes are difficult to capture within the typical duration of a trial. Therefore, predictors for disease progression are needed. We assessed if temporal increase of fat fraction (FF) in BMD follows a sigmoidal trajectory and whether fat fraction at baseline (FFbase) could therefore predict FF increase after 2 years (ΔFF). Thereafter, for two different MR-based parameters, we tested the additional predictive value to FFbase. We used 3-T Dixon data from the upper and lower leg, and multiecho spin-echo MRI and 7-T ³¹ P MRS datasets from the lower leg, acquired in 24 BMD patients (age: 41.4 [SD 12.8] years). We assessed the pattern of increase in FF using mixed-effects modelling. Subsequently, we tested if indicators of muscle damage like standard deviation in water T₂ (stdT₂ ) and the phosphodiester (PDE) over ATP ratio at baseline had additional value to FFbase for predicting ∆FF. The association between FFbase and ΔFF was described by the derivative of a sigmoid function and resulted in a peak ΔFF around 0.45 FFbase (fourth-order polynomial term: t = 3.7, p < .001). StdT₂ and PDE/ATP were not significantly associated with ∆FF if FFbase was included in the model. The relationship between FFbase and ∆FF suggests a sigmoidal trajectory of the increase in FF over time in BMD, similar to that described for Duchenne muscular dystrophy. Our results can be used to identify muscles (or patients) that are in the fast progressing stage of the disease, thereby facilitating the conduct of clinical trials.

Oxidative Stress, Inflammation and Connexin Hemichannels in Muscular Dystrophies

Muscular dystrophies (MDs) are a heterogeneous group of congenital neuromuscular disorders whose clinical signs include myalgia, skeletal muscle weakness, hypotonia, and atrophy that leads to progressive muscle disability and loss of ambulation. MDs can also affect cardiac and respiratory muscles, impairing life-expectancy. MDs in clude Duchenne muscular dystrophy, Emery-Dreifuss muscular dystrophy, facioscapulohumeral muscular dystrophy and limb-girdle muscular dystrophy. These and other MDs are caused by mutations in genes that encode proteins responsible for the structure and function of skeletal muscles, such as components of the dystrophin-glycoprotein-complex that connect the sarcomeric-actin with the extracellular matrix, allowing contractile force transmission and providing stability during muscle contraction. Consequently, in dystrophic conditions in which such proteins are affected, muscle integrity is disrupted, leading to local inflammatory responses, oxidative stress, Ca²⁺-dyshomeostasis and muscle degeneration. In this scenario, dysregulation of connexin hemichannels seem to be an early disruptor of the homeostasis that further plays a relevant role in these processes. The interaction between all these elements constitutes a positive feedback loop that contributes to the worsening of the diseases. Thus, we discuss here the interplay between inflammation, oxidative stress and connexin hemichannels in the progression of MDs and their potential as therapeutic targets.

Role Attainment in Emerging Adulthood: Subjective Evaluation by Male Adolescents and Adults with Duchenne and Becker Muscular Dystrophy

BACKGROUND

Youth with Duchenne and Becker muscular dystrophy (DBMD) experience challenges in attaining adult roles, which may impact quality of life. New interventions and treatments may facilitate adult role attainment through improved function. Historical data on adult role attainment is important to assess the impact of new interventions on teens and young adults with DBMD. This study assesses medical knowledge, independence and employment, and relationships among adolescents and young adults with DBMD.

METHODS

This study uses data from a 2013 Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet) survey on adult transition. Males with DBMD aged 16-30 years were included.

RESULTS

Sixty-five of 258 eligible males participated; we report results on 60 participants with an MD STARnet case definition of DMD or BMD. Individuals with BMD reported higher rates than those with DMD of frequently staying home without supervision (50% BMD; 14% DMD), independently performing daily physical needs (93% BMD; 7% DMD) and being employed full or part time (33% BMD; 4% DMD). Most participants understood medication and physical therapy goals; less than half indicated being often or always responsible for scheduling DMBD-related management and refilling medications. Most had not been in a romantic relationship but reported desiring such relationships.

CONCLUSIONS

Our data reinforce the impact of DMD (and to a lesser extent, BMD) on transition to adult roles. These results provide an important historical comparator for teen and adult patients who are trying new interventions and therapies. Such data are important for assessing the quality-of-life impact of new treatments and to inform support and training programs for people with DBMD as they transition to new adult roles and responsibilities.

Assessing Cognitive Function in Neuromuscular Diseases: A Pilot Study in a Sample of Children and Adolescents

Central nervous system (CNS) involvement has been variously studied in pediatric neuromuscular disorders (NMDs). The primary goal of this study was to assess cognitive functioning in NMDs, and secondary aims were to investigate possible associations of cognitive impairment with motor impairment, neurodevelopmental delay, and genotype. This was a cross-sectional study of 43 pediatric patients, affected by six NMDs. Myotonic dystrophy type 1 (DM1) and glycogen storage disease type 2 (GSD2) patients had a delay on the Bayley-III scales. On Wechsler scales, DMD and DM1 patients showed lower FSIQ scores, with an intellectual disability (ID) in 27% and 50%, respectively. FSIQ was normal in Becker muscular dystrophy (BMD), GSD2, and hereditary motor sensory neuropathy (HMSN) patients, while higher individual scores were found in the spinal muscular atrophy (SMA) group. In the DM1 cohort, lower FSIQ correlated with worse motor performance (ρ = 0.84, p < 0.05), and delayed speech acquisition was associated with ID (p = 0.048), with worse cognitive impairment in the congenital than in the infantile form (p = 0.04). This study provides further evidence of CNS in some NMDs and reinforces the need to include cognitive assessment in protocols of care of selected pediatric NMDs.

ActRIIB:ALK4-Fc alleviates muscle dysfunction and comorbidities in murine models of neuromuscular disorders

Patients with neuromuscular disorders suffer from a lack of treatment options for skeletal muscle weakness and disease comorbidities. Here, we introduce as a potential therapeutic agent a heterodimeric ligand-trapping fusion protein, ActRIIB:ALK4-Fc, which comprises extracellular domains of activin-like kinase 4 (ALK4) and activin receptor type IIB (ActRIIB), a naturally occurring pair of type I and II receptors belonging to the TGF-β superfamily. By surface plasmon resonance (SPR), ActRIIB:ALK4-Fc exhibited a ligand binding profile distinctly different from that of its homodimeric variant ActRIIB-Fc, sequestering ActRIIB ligands known to inhibit muscle growth but not trapping the vascular regulatory ligand bone morphogenetic protein 9 (BMP9). ActRIIB:ALK4-Fc and ActRIIB-Fc administered to mice exerted differential effects - concordant with SPR results - on vessel outgrowth in a retinal explant assay. ActRIIB:ALK4-Fc induced a systemic increase in muscle mass and function in wild-type mice and in murine models of Duchenne muscular dystrophy (DMD), amyotrophic lateral sclerosis (ALS), and disuse atrophy. Importantly, ActRIIB:ALK4-Fc improved neuromuscular junction abnormalities in murine models of DMD and presymptomatic ALS and alleviated acute muscle fibrosis in a DMD model. Furthermore, in combination therapy ActRIIB:ALK4-Fc increased the efficacy of antisense oligonucleotide M12-PMO on dystrophin expression and skeletal muscle endurance in an aged DMD model. ActRIIB:ALK4-Fc shows promise as a therapeutic agent, alone or in combination with dystrophin rescue therapy, to alleviate muscle weakness and comorbidities of neuromuscular disorders.

Dystrophin gene editing by CRISPR/Cas9 system in human skeletal muscle cell line (HSkMC)

OBJECTIVES

Duchene muscular dystrophy (DMD) is a progressive neuromuscular disease caused by mutations in the DMD gene, resulting in the absence of dystrophin expression leading to membrane fragility and myofibril necrosis in the muscle cells. Because of progressive weakness in the skeletal and cardiac muscles, premature death is inevitable. There is no curative treatment available for DMD. In recent years, advances in genetic engineering tools have made it possible to manipulate gene sequences and accurately modify disease-causing mutations. CRISPR/Cas9 technology is a promising tool for gene editing because of its ability to induce double-strand breaks in the DNA.

MATERIALS AND METHODS

In this study for the exon-skipping approach, we designed a new pair of guide RNAs (gRNA) to induce large deletion of exons 48 to 53 in the DMD gene in the human skeletal muscle cell line (HSkMC), in order to correct the frame of the gene.

RESULTS

Data showed successful editing of DMD gene by deletion of exons 48 to 53 and correction of the reading frame in edited cells. Despite a large deletion in the edited DMD gene, the data of real-time PCR, immune florescent staining demonstrated successful expression of truncated dystrophin in edited cells.

CONCLUSION

This study demonstrated that the removal of exons 48-53 by the CRISPR / Cas9 system did not alter the expression of the DMD gene due to the preservation of the reading frame of the gene.

Vitamin D Level Stability in Dystrophinopathy Patients on Vitamin D Supplementation

BACKGROUND

Expert guidelines recommend annual monitoring of 25-hydroxyvitamin D (25-OHD) and maintaining 25-OHD ≥30 ng/ml in patients with dystrophinopathies.

OBJECTIVE

We hypothesized that 25-OHD remains stable and requires less frequent monitoring in patients taking stable maintenance doses of vitamin D.

METHODS

We performed a retrospective cohort study, using the electronic health record to identify 26 patients with dystrophinopathies with a baseline 25-OHD ≥30 ng/mL and at least one additional 25-OHD measurement. These patients had received a stable dose of vitamin D for ≥3 months prior to their baseline 25-OHD measurement and throughout follow-up. The main outcome measured was the mean duration time the subjects spent with a 25-OHD ≥30 ng/mL.

RESULTS

Only 19% of patients dropped their 25-OHD to < 30 ng/ml, with a mean time to drop of 33 months and a median nadir 25-OHD of 28 ng/mL.

CONCLUSIONS

These results suggest that measurement of 25-OHD every 2-2.5 years may be sufficient in patients with a baseline 25-OHD ≥30 ng/mL and who are on a stable maintenance dose of vitamin D. Other patients may require more frequent assessments.

Coping in Children and Adolescents with a Genetic Muscle Disorder -Findings from a Population-Based Study

BACKGROUND

The impact of genetic muscle disorders on quality of life in affected children are well-documented. However, few studies have investigated children's coping strategies and relationships between coping and quality of life.

OBJECTIVES

To determine coping strategy use, efficacy, and associations with quality of life in children with a genetic muscle disorder.

METHODS

Forty-eight children (6-15 years, 58%male) with a genetic muscle disorder were identified as part of a national prevalence study. Children completed the Kidcope in response to a specific stressor (doctors visits) and the Pediatric Quality of Life Inventory Neuromuscular Module.

RESULTS

'Wishful thinking' (75%, 36/48) and 'cognitive restructuring' (71%, 34/48) were the most frequently used coping strategies. 'Self-criticism' (12%, 6/48), and blaming others' and 'resignation' (both 19%, 9/48) were the least used strategies. Coping strategy use did not differ across age andsex groups (p's from 0.08 to 1.00). Positive coping strategies tended to be more effective (medians from 2.00 to 2.75) than negative strategies (medians ranged from 1.38 to 2.50). Using a greater number of different types of positive (F(4, 46) = 5.79, p = 0.001) and/or negative (F(4, 44) = 5.64, p 0.001) coping strategies was linked to poorer health-related quality of life.

CONCLUSION

We conclude that children with genetic muscle disorders use a wide range of positive and/or negative coping strategies in response to stressors associated with a doctor visit and may benefit from greater support to improve health-related quality of life. Findings support the value of routine screening of children's coping to identify those who would benefit from support.

The clinical course of Duchenne muscular dystrophy in the corticosteroid treatment era: a systematic literature review

Background

Duchenne muscular dystrophy (DMD) is a severe rare progressive inherited neuromuscular disorder, leading to loss of ambulation (LOA) and premature mortality. The standard of care for patients with DMD has been treatment with corticosteroids for the past decade; however a synthesis of contemporary data describing the clinical course of DMD is lacking. The objective was to summarize age at key clinical milestones (loss of ambulation, scoliosis, ventilation, cardiomyopathy, and mortality) in the corticosteroid-treatment-era.

Methods

A systematic review was conducted using MEDLINE and EMBASE. The percentage experiencing key clinical milestones, and the mean or median age at those milestones, was synthesized from studies from North American populations, published between 2007 and 2018.

Results

From 5637 abstracts, 29 studies were included. Estimates of the percentage experiencing key clinical milestones, and age at those milestones, showed heterogeneity. Up to 30% of patients lost ambulation by age 10 years, and up to 90% by 15 years of age. The mean age at scoliosis onset was approximately 14 years. Ventilatory support began from 15 to 18 years, and up to half of patients required ventilation by 20 years of age. Registry-based estimates suggest that 70% had evidence of cardiomyopathy by 15 years and almost all by 20 years of age. Finally, mortality rates up to 16% by age 20 years were reported; among those surviving to adulthood mortality was up to 60% by age 30 years.

Conclusions

Contemporary natural history studies from North America report that LOA on average occurs in the early teens, need for ventilation and cardiomyopathy in the late teens, and death in the third or fourth decade of life. Variability in rates may be due to differences in study design, treatment with corticosteroids or other disease-modifying agents, variations in clinical practices, and dystrophin mutations. Despite challenges in synthesizing estimates, these findings help characterize disease progression among contemporary North American DMD patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01862-w.

Everyday Life Participation Using Powered Wheelchair Standing Devices by Boys With DMD

Powered wheelchair standing devices (PWSDs) allow supported standing for activity; however, little is known about their use. To understand factors affecting use of supported standing for participation among boys with Duchenne muscular dystrophy (DMD) and characteristics of successful users, we gathered data over 7 days from boys who had used PWSDs for 24 months, using a smartphone application. We used descriptive statistics to identify factors that affected their participation. Physical/social engagement and independence were motivators for standing in PWSDs. Enablers included positive attitudinal/social environments. Barriers included pain during supported standing and lack of physical environment accessibility. The characteristics of successful users were identified. Supported standing via PWSDs has potential to improve participation for boys with DMD. The disease stage, individual personal factors and environmental supports impact on use. Therapists should carefully consider and manage factors that impact on uptake and sustainability of use.

Oxidative Stress, Inflammation, and Activators of Mitochondrial Biogenesis: Tempol Targets in the Diaphragm Muscle of Exercise Trained-mdx Mice

The mdx mouse phenotype aggravated by chronic exercise on a treadmill makes this murine model more reliable for the study of muscular dystrophy. Thus, to better assess the Tempol effect on dystrophic pathways, the analyses in this study were performed in the blood samples and diaphragm muscle from treadmill trained adult (7–11-weeks old) mdx animals. The mdx mice were divided into three groups: mdxSed, sedentary controls (n = 28); mdxEx, exercise-trained animals (n = 28); and mdxEx+T, exercise-trained animals with the Tempol treatment (n = 28). The results demonstrated that the Tempol treatment promoted muscle strength gain, prevented muscle damage, reduced the inflammatory process, oxidative stress, and angiogenesis regulator, and up regulated the activators of mitochondrial biogenesis. The main new findings of this study are that Tempol reduced the NF-κB and increased the PGC1-α and PPARδ levels in the exercise-trained-mdx mice, which are probably related to the ability of this antioxidant to scavenge excessive ROS. These results reinforce the use of Tempol as a potential therapeutic strategy in DMD.

Beneficial Role of Exercise in the Modulation of mdx Muscle Plastic Remodeling and Oxidative Stress

Duchenne muscular dystrophy (DMD) is an X-linked recessive progressive lethal disorder caused by the lack of dystrophin, which determines myofibers mechanical instability, oxidative stress, inflammation, and susceptibility to contraction-induced injuries. Unfortunately, at present, there is no efficient therapy for DMD. Beyond several promising gene- and stem cells-based strategies under investigation, physical activity may represent a valid noninvasive therapeutic approach to slow down the progression of the pathology. However, ethical issues, the limited number of studies in humans and the lack of consistency of the investigated training interventions generate loss of consensus regarding their efficacy, leaving exercise prescription still questionable. By an accurate analysis of data about the effects of different protocol of exercise on muscles of mdx mice, the most widely-used pre-clinical model for DMD research, we found that low intensity exercise, especially in the form of low speed treadmill running, likely represents the most suitable exercise modality associated to beneficial effects on mdx muscle. This protocol of training reduces muscle oxidative stress, inflammation, and fibrosis process, and enhances muscle functionality, muscle regeneration, and hypertrophy. These conclusions can guide the design of appropriate studies on human, thereby providing new insights to translational therapeutic application of exercise to DMD patients.

The experience of Colombian boys and young men living with Duchenne muscular dystrophy

Abstract Duchenne muscular dystrophy (DMD) is a chronic disease that primarily affects males and is characterized by progressive physical impairment and, eventually, death. This qualitative study aimed to explore and understand the experience of diagnosis and disease in young people with DMD living in Bogotá, Colombia. After securing approval from the Research Ethics Committee (CEI-ABN026-000311), nine individuals took part of a semi-structured interview, and their narratives were analyzed using thematic analysis. The main topics developed throughout the narratives were: negative representation of the disease; fear; difficulty expressing emotions; the patient-doctor relationship; the wheelchair; the caregivers and coping strategies. We conclude that young people affected by DMD face several challenging experiences that underscore the need for better, more respectful, and compassionate interactions with healthcare providers. Also, their experiences are indicative of a socio-cultural context that needs to become more responsive and compassionate towards young people and disability.

Detailed genetic and functional analysis of the hDMDdel52/mdx mouse model

Duchenne muscular dystrophy (DMD) is a severe, progressive neuromuscular disorder caused by reading frame disrupting mutations in the DMD gene leading to absence of functional dystrophin. Antisense oligonucleotide (AON)-mediated exon skipping is a therapeutic approach aimed at restoring the reading frame at the pre-mRNA level, allowing the production of internally truncated partly functional dystrophin proteins. AONs work in a sequence specific manner, which warrants generating humanized mouse models for preclinical tests. To address this, we previously generated the hDMDdel52/mdx mouse model using transcription activator like effector nuclease (TALEN) technology. This model contains mutated murine and human DMD genes, and therefore lacks mouse and human dystrophin resulting in a dystrophic phenotype. It allows preclinical evaluation of AONs inducing the skipping of human DMD exons 51 and 53 and resulting in restoration of dystrophin synthesis. Here, we have further characterized this model genetically and functionally. We discovered that the hDMD and hDMDdel52 transgene is present twice per locus, in a tail-to-tail-orientation. Long-read sequencing revealed a partial deletion of exon 52 (first 25 bp), and a 2.3 kb inversion in intron 51 in both copies. These new findings on the genomic make-up of the hDMD and hDMDdel52 transgene do not affect exon 51 and/or 53 skipping, but do underline the need for extensive genetic analysis of mice generated with genome editing techniques to elucidate additional genetic changes that might have occurred. The hDMDdel52/mdx mice were also evaluated functionally using kinematic gait analysis. This revealed a clear and highly significant difference in overall gait between hDMDdel52/mdx mice and C57BL6/J controls. The motor deficit detected in the model confirms its suitability for preclinical testing of exon skipping AONs for human DMD at both the functional and molecular level.

Tempol improves redox status in mdx dystrophic diaphragm muscle

Oxidative stress is a critical element in relationship to the pathophysiology of Duchenne muscular dystrophy (DMD). In the mice the diaphragm (DIA) is most resembles the dystrophic human pathology. In this study we have evaluated the consequences of a synthetic antioxidant (tempol) on oxidative stress parameters in the DIA muscle of mdx mice. The mdx mice were separated into two groups: mdx, the control group receiving intraperitoneal (i.p.) injections of saline solution (100 µL), and mdxT, the treated group receiving i.p. injections of tempol (100 mg/kg). The tempol-treated group showed reduced oxidative stress markers, decreasing the dihydroethidium reaction (DHE) area; autofluorescent lipofuscin granules; and 4-hydroxynonenal (4-HNE)-protein adduct levels. DIA muscle of mdx mice. At the same time, the manganese-superoxide dismutase 2 (SOD2) levels were increased in the tempol-treated group. In addition, the tempol-treated group showed reduced levels of glutathione-disulphide reductase (GSR), glutathione peroxidase 1 (GPx1) and catalase (CAT) in immunoblots. The tempol-treated group has also shown lower relative gene expression of SOD1, CAT and GPx than the non-treated group. Our data demonstrated that tempol treatment reduced oxidant parameters and increased anti-oxidant SOD2 levels in the DIA muscle of mdx mice, which may contribute to the normalization of the redox homeostasis of dystrophic muscles.

Single Cell ADNP Predictive of Human Muscle Disorders: Mouse Knockdown Results in Muscle Wasting

Activity-dependent neuroprotective protein (ADNP) mutations are linked with cognitive dysfunctions characterizing the autistic-like ADNP syndrome patients, who also suffer from delayed motor maturation. We thus hypothesized that ADNP is deregulated in versatile myopathies and that local ADNP muscle deficiency results in myopathy, treatable by the ADNP fragment NAP. Here, single-cell transcriptomics identified ADNP as a major constituent of the developing human muscle. ADNP transcript concentrations further predicted multiple human muscle diseases, with concentrations negatively correlated with the ADNP target interacting protein, microtubule end protein 1 (EB1). Reverting back to modeling at the single-cell level of the male mouse transcriptome, Adnp mRNA concentrations age-dependently correlated with motor disease as well as with sexual maturation gene transcripts, while Adnp expressing limb muscle cells significantly decreased with aging. Mouse Adnp heterozygous deficiency exhibited muscle microtubule reduction and myosin light chain (Myl2) deregulation coupled with motor dysfunction. CRISPR knockdown of adult gastrocnemius muscle Adnp in a Cas9 mouse resulted in treadmill (male) and gait (female) dysfunctions that were specifically ameliorated by treatment with the ADNP snippet, microtubule interacting, Myl2-regulating, NAP (CP201). Taken together, our studies provide new hope for personalized diagnosis/therapeutics in versatile myopathies.

Age and Sex-Dependent ADNP Regulation of Muscle Gene Expression Is Correlated with Motor Behavior: Possible Feedback Mechanism with PACAP

The activity-dependent neuroprotective protein (ADNP), a double-edged sword, sex-dependently regulates multiple genes and was previously associated with the control of early muscle development and aging. Here we aimed to decipher the involvement of ADNP in versatile muscle gene expression patterns in correlation with motor function throughout life. Using quantitative RT-PCR we showed that Adnp^+/− heterozygous deficiency in mice resulted in aberrant gastrocnemius (GC) muscle, tongue and bladder gene expression, which was corrected by the Adnp snippet, drug candidate, NAP (CP201). A significant sexual dichotomy was discovered, coupled to muscle and age-specific gene regulation. As such, Adnp was shown to regulate myosin light chain (Myl) in the gastrocnemius (GC) muscle, the language acquisition gene forkhead box protein P2 (Foxp2) in the tongue and the pituitary-adenylate cyclase activating polypeptide (PACAP) receptor PAC1 mRNA (Adcyap1r1) in the bladder, with PACAP linked to bladder function. A tight age regulation was observed, coupled to an extensive correlation to muscle function (gait analysis), placing ADNP as a muscle-regulating gene/protein.

The patient with severe traumatic brain injury: clinical decision-making: the first 60 min and beyond

PURPOSE OF REVIEW

There is an urgent need to discuss the uncertainties and paradoxes in clinical decision-making after severe traumatic brain injury (s-TBI). This could improve transparency, reduce variability of practice and enhance shared decision-making with proxies.

RECENT FINDINGS

Clinical decision-making on initiation, continuation and discontinuation of medical treatment may encompass substantial consequences as well as lead to presumed patient benefits. Such decisions, unfortunately, often lack transparency and may be controversial in nature. The very process of decision-making is frequently characterized by both a lack of objective criteria and the absence of validated prognostic models that could predict relevant outcome measures, such as long-term quality and satisfaction with life. In practice, while treatment-limiting decisions are often made in patients during the acute phase immediately after s-TBI, other such severely injured TBI patients have been managed with continued aggressive medical care, and surgical or other procedural interventions have been undertaken in the context of pursuing a more favorable patient outcome. Given this spectrum of care offered to identical patient cohorts, there is clearly a need to identify and decrease existing selectivity, and better ascertain the objective criteria helpful towards more consistent decision-making and thereby reduce the impact of subjective valuations of predicted patient outcome.

SUMMARY

Recent efforts by multiple medical groups have contributed to reduce uncertainty and to improve care and outcome along the entire chain of care. Although an unlimited endeavor for sustaining life seems unrealistic, treatment-limiting decisions should not deprive patients of a chance on achieving an outcome they would have considered acceptable.

Coenzyme Q10 supplementation acts as antioxidant on dystrophic muscle cells

Increased oxidative stress is a frequent feature in Duchenne muscular dystrophy (DMD). High reactive oxygen species (ROS) levels, associated with altered enzyme antioxidant activity, have been reported in dystrophic patients and mdx mice, an experimental model of DMD. In this study, we investigated the effects of coenzyme Q10 (CoQ10) on oxidative stress marker levels and calcium concentration in primary cultures of dystrophic muscle cells from mdx mice. Primary cultures of skeletal muscle cells from C57BL/10 and mdx mice were treated with coenzyme Q10 (5 μM) for 24 h. The untreated mdx and C57BL/10 muscle cells were used as controls. The MTT and live/dead cell assays showed that CoQ10 presented no cytotoxic effect on normal and dystrophic muscle cells. Intracellular calcium concentration, H2O2 production, 4-HNE, and SOD-2 levels were higher in mdx muscle cells. No significant difference in the catalase, GPx, and Gr levels was found between experimental groups. This study demonstrated that CoQ10 treatment was able to reduce levels of oxidative stress markers, such as H2O2, acting as an antioxidant, as well as decreasing abnormal intracellular calcium influx in dystrophic muscles cells. This study demonstrated that CoQ10 treatment was able to reduce levels of oxidative stress markers, such as H2O2, acting as an antioxidant, as well as decreasing abnormal intracellular calcium influx in dystrophic muscles cells. Our findings also suggest that the decrease of oxidative stress reduces the need for upregulation of antioxidant pathways, such as SOD and GSH.

Tempol treatment shows phenotype improvement in mdx mice

Considering potential Tempol effects on mdx muscle fibers, in this study we evaluated its effects on relevant dystrophic phenotypic characteristics, such as muscle degeneration, inflammatory process and angiogenesis, which as yet have not been investigated. Mdx mice were randomly assigned into three groups: mdxS, the control group receiving intraperitoneal (i.p.) injections of saline solution (100μL); mdxP, positive control group receiving prednisolone (1mg/kg) by oral gavage; and mdxT, treated group receiving i.p. injections of tempol (100 mg/kg). C57BL/10 mice were also used as controls. Tempol treatment promoted gain in muscle strength and reduced myonecrosis and inflammatory response in the dystrophic diaphragm (DIA) and biceps brachii (BB) muscles. No evidence of Tempol's beneficial performance on angiogenesis in DIA and BB mdx muscles was found. The findings presented here show that Tempol treatment improves dystrophic phenotype, supporting its use as a potential therapeutic strategy in DMD.

CRISPR Correction of Duchenne Muscular Dystrophy

The ability to efficiently modify the genome using CRISPR technology has rapidly revolutionized biology and genetics and will soon transform medicine. Duchenne muscular dystrophy (DMD) represents one of the first monogenic disorders that has been investigated with respect to CRISPR-mediated correction of causal genetic mutations. DMD results from mutations in the gene encoding dystrophin, a scaffolding protein that maintains the integrity of striated muscles. Thousands of different dystrophin mutations have been identified in DMD patients, who suffer from a loss of ambulation followed by respiratory insufficiency, heart failure, and death by the third decade of life. Using CRISPR to bypass DMD mutations, dystrophin expression has been efficiently restored in human cells and mouse models of DMD. Here, we review recent progress toward the development of possible CRISPR therapies for DMD and highlight opportunities and potential obstacles in attaining this goal.