Dystrophy Patients Research Articles

The Gut Microbiota Involvement in the Panorama of Muscular Dystrophy Pathogenesis

Muscular dystrophies (MDs) are genetically heterogeneous diseases characterized by primary skeletal muscle atrophy. The collapse of muscle structure and irreversible degeneration of tissues promote the occurrence of comorbidities, including cardiomyopathy and respiratory failure. Mitochondrial dysfunction leads to inflammation, fibrosis, and adipogenic cellular infiltrates that exacerbate the symptomatology of MD patients. Gastrointestinal disorders and metabolic anomalies are common in MD patients and may be determined by the interaction between the intestine and its microbiota. Therefore, the gut–muscle axis is one of the actors involved in the spread of inflammatory signals to all muscles. In this review, we aim to examine in depth how intestinal dysbiosis can modulate the metabolic state, the immune response, and mitochondrial biogenesis in the course and progression of the most investigated MDs such as Duchenne Muscular Dystrophy (DMD) and Myotonic Dystrophy (MD1), to better identify gut microbiota metabolites working as therapeutic adjuvants to improve symptoms of MD.

Genetic Panel Reveals Coexisting Neuromuscular Disorders in Patients With Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy is a genetically based neuromuscular disorder characterized by progressive physical impairment and cardiomyopathy in children, leading to fatal cardiac or respiratory failure. Duchenne muscular dystrophy shares some overlapping clinical features with other disorders, complicating clinical differentiation. We hypothesized that some Duchenne muscular dystrophy patients may have a secondary neuromuscular disorders that could negatively skew data during pharmaceutical clinical trials and lead to incomplete treatment plans. Consecutive genetic panels on 353 patients were reviewed. Thirty-two (32; 9.1%) patients with Duchenne muscular dystrophy were identified. Three (3; 9.4%) were found to have at least 1 genetically confirmed secondary neuromuscular disorder. Overlooking these coexisting disorders could lead to unexpected treatment failures, potentially affecting medication efficacy in trials or commercial use. Secondary neuromuscular disorders should be considered in Duchenne muscular dystrophy patients before clinical trial enrollment or treatment planning, with expanded genetic testing, such as whole exome sequencing or whole genome sequencing, likely to reveal even more secondary disorders.

Histone deacetylase 6 inhibition promotes microtubule acetylation and facilitates autophagosome-lysosome fusion in dystrophin-deficient mdx mice.

Duchenne muscular dystrophy is a progressive muscle-wasting disease caused by mutations in the dystrophin gene. Despite progress in dystrophin-targeted gene therapies, it is still a fatal disease requiring novel therapeutics that can be used synergistically or alternatively to emerging gene therapy. Defective autophagy and disorganized microtubule networks contribute to dystrophic pathogenesis, yet the mechanisms by which microtubule alterations regulate autophagy remain elusive. The present study was designed to uncover possible mechanisms underpinning the role of microtubules in regulating autophagy in dystrophic mice. Mdx mice were also supplemented with Tubastatin A, a pharmacological inhibitor of histone deacetylase 6, and pathophysiology was assessed. Mdx mice with a genetic deletion of the Nox-2 scaffolding subunit p47phox were used to assess redox dependence on tubulin acetylation. Our data show decreased acetylation of α-tubulin with enhanced histone deacetylase 6 expression. Tubastatin A increases tubulin acetylation and Q-SNARE complex formation but does not alter microtubule organization or density, indicating improved autophagosome-lysosome fusion. Tubastatin A increases the acetylation of peroxiredoxin and protects it from hyper-oxidation, hence modulating intracellular redox status in mdx mice. Tubastatin A reduces muscle damage and enhances force production. Genetic down regulation of Nox2 activity in the mdx mice promotes autophagosome maturation but not autolysosome formation. Our data highlight that autophagy is differentially regulated by redox and acetylation in mdx mice. By improving autophagy through promoting tubulin acetylation, Tubastatin A decreases the dystrophic phenotype and improves muscle function, suggesting a great potential for clinical translation and treating dystrophic patients.

231P Efficacy of tranilast in preventing exacerbating cardiac function and death from heart failure in muscular dystrophy patients with advanced-stage heart failure: a single-arm, open-label, multicenter study

231P Efficacy of tranilast in preventing exacerbating cardiac function and death from heart failure in muscular dystrophy patients with advanced-stage heart failure: a single-arm, open-label, multicenter study

309P Cholesterol defects in muscular dystrophy patients and mice cause ambulation dysfunction: insight into statin- and anti-HMGCoAR-induced myopathies

309P Cholesterol defects in muscular dystrophy patients and mice cause ambulation dysfunction: insight into statin- and anti-HMGCoAR-induced myopathies

332P Physician and caregiver concordance in Duchenne muscular dystrophy patients in Europe, Japan, and the USA: a multi-national survey

332P Physician and caregiver concordance in Duchenne muscular dystrophy patients in Europe, Japan, and the USA: a multi-national survey

356P A retrospective review of adult Duchenne muscular dystrophy patients in a UK centre of excellence and report the results of adherence to the standards of care guidelines for cardiac management

356P A retrospective review of adult Duchenne muscular dystrophy patients in a UK centre of excellence and report the results of adherence to the standards of care guidelines for cardiac management

611P Empowering patient decision-making and enhancing clinical care through the UK Duchenne muscular dystrophy patient data collection platform

611P Empowering patient decision-making and enhancing clinical care through the UK Duchenne muscular dystrophy patient data collection platform

599P The UK Facioscapulohumeral Muscular Dystrophy Patient Registry: a powerful tool to support clinical research and patient voice in the translational research pathway

599P The UK Facioscapulohumeral Muscular Dystrophy Patient Registry: a powerful tool to support clinical research and patient voice in the translational research pathway

333P Real-World symptom progression in Duchenne muscular dystrophy patients in Europe, Japan, and the USA: results from a multi-national survey

333P Real-World symptom progression in Duchenne muscular dystrophy patients in Europe, Japan, and the USA: results from a multi-national survey

608P Collection of real-world data for Duchenne muscular dystrophy patients through a national registry: description of the current cohort in the UK

608P Collection of real-world data for Duchenne muscular dystrophy patients through a national registry: description of the current cohort in the UK

386P Dark-adaptation visual thresholds in Duchenne muscular dystrophy patients with genetic backgrounds affecting different dystrophin proteins

386P Dark-adaptation visual thresholds in Duchenne muscular dystrophy patients with genetic backgrounds affecting different dystrophin proteins

604P Descriptive analysis of Duchenne muscular dystrophy patients included in the Swedish National Registry for neuromuscular disorders

604P Descriptive analysis of Duchenne muscular dystrophy patients included in the Swedish National Registry for neuromuscular disorders

The Innovative Role of Nuclear Receptor Interaction Protein in Orchestrating Invadosome Formation for Myoblast Fusion.

Nuclear receptor interaction protein (NRIP) is versatile and engages with various proteins to execute its diverse biological function. NRIP deficiency was reported to cause small myofibre size in adult muscle regeneration, indicating a crucial role of NRIP in myoblast fusion. The colocalization and interaction of NRIP with actin were investigated by immunofluorescence and immunoprecipitation assay, respectively. The participation of NRIP in myoblast fusion was demonstrated by cell fusion assay and time-lapse microscopy. The NRIP mutants were generated for mechanism study in NRIP-null C2C12 (termed KO19) cells and muscle-specific NRIP knockout (NRIP cKO) mice. A GEO profile database was used to analyse NRIP expression in Duchenne muscular dystrophy (DMD) patients. In this study, we found that NRIP directly and reciprocally interacted with actin both invitro and in cells. Immunofluorescence microscopy showed that the endogenous NRIP colocalized with components of invadosome, such as actin, Tks5, and cortactin, at the tips of cells during C2C12 differentiation. The KO19 cells were generated and exhibited a significant deficit in myoblast fusion compared with wild-type C2C12 cells (3.16% vs. 33.67%, p < 0.005). Overexpressed NRIP in KO19 cells could rescue myotube formation compared with control (3.37% vs. 1.00%, p < 0.01). We further confirmed that NRIP directly participated in cell fusion by using a cell-cell fusion assay. We investigated the mechanism of invadosome formation for myoblast fusion, which depends on NRIP-actin interaction, by analysing NRIP mutants in NRIP-null cells. Loss of actin-binding of NRIP reduced invadosome (enrichment ratio, 1.00 vs. 2.54, p < 0.01) and myotube formation (21.82% vs. 35.71%, p < 0.05) in KO19 cells and forced NRIP expression in KO19 cells and muscle-specific NRIP knockout (NRIP cKO) mice increased myofibre size compared with controls (over 1500 μm2, 61.01% vs. 20.57%, p < 0.001). We also found that the NRIP mRNA level was decreased in DMD patients compared with healthy controls (18 072 vs. 28 289, p < 0.001, N = 10 for both groups). NRIP is a novel actin-binding protein for invadosome formation to induce myoblast fusion.

Muscular dystrophy patients show low exercise‐induced blood flow in muscles with normal strength

AbstractObjectiveNeuromuscular evaluation increasingly employs muscle ultrasonography to determine muscle thickness, mean grayscale echointensity, and visual semiquantitative echotexture attenuation. However, these measures provide low sensitivity for detection of mild muscle abnormality. Exercise‐induced intramuscular blood flow is a physiologic phenomenon, which may be impaired in mildly affected muscles, particularly in dystrophinopathies, and may indicate functional muscle ischemia. We aimed to determine if muscle blood flow is reduced in patients with neuromuscular disorders and preserved muscle strength, and if it correlates with echointensity and digital echotexture measurements.MethodsPeak exercise‐induced blood flow, echointensity, and echotexture were quantified in the elbow flexor muscles of 15 adult patients with Becker muscular dystrophy (BMD) and 13 patients with other muscular dystrophies (OMD). These were compared to 17 patients with Charcot–Marie–Tooth type 1 (CMT1) neuropathy and 21 healthy adults from a previous study.ResultsMuscle blood flow was reduced in all patient groups compared to controls, most prominently in BMD patients (p &lt; 0.0001). Echointensity was similarly increased in all patient groups (p &lt; 0.05), while echotexture was reduced only in muscular dystrophy patients (p ≤ 0.002). In BMD, blood flow correlated with echotexture (Pearson r = 0.6098, p = 0.0158) and strength (Spearman r = 0.5471; p = 0.0370). In patients with normal muscle strength, reduced muscle blood flow was evident in all patient groups (p &lt; 0.001), echotexture was reduced in BMD and OMD (p &lt; 0.01), and echointensity was increased in CMT (p &lt; 0.05).InterpretationMuscle blood flow is a sensitive measure to detect abnormality, even in muscles with normal strength. Increased echointensity may indicate a neurogenic disorder when strength is preserved, while low echotexture suggests a dystrophic disease.

Single cell and TCR analysis of immune cells from AAV gene therapy-dosed Duchenne muscular dystrophy patients

Clinical trials for Duchenne muscular dystrophy (DMD) are assessing the therapeutic efficacy of systemically delivered adeno-associated virus (AAV) carrying a modified DMD transgene. High vector doses (>1E14 vg/kg) are needed to globally transduce skeletal muscles; however, such doses trigger immune-related adverse events. Mitigating these immune responses is crucial for widespread application of AAV-based therapies. We used single-cell RNA-sequencing and T-cell receptor (TCR)-sequencing on peripheral blood mononuclear cells from five participants prior to, and after, dosing. One subject in the high-dose cohort experienced thrombotic microangiopathy (TMA). Few changes in cell frequencies occurred after treatment; however, differential gene expression demonstrated induction of interferon response genes in most T-cell types. T-cell clonotype and clumping analysis showed the expansion or appearance of groups of related TCR sequences in the post-treatment samples. Three of these expanded clumps could be assigned to prior Human Herpesvirus infections, two of which were present in the participant that exhibited TMA. These data provide insight on the mechanistic basis of human immune-AAV interactions and lay a foundation for improved understanding of why TMA arises in some patients and not others.

Clinical Diagnosis and Genetic Analysis of Children With Muscular Dystrophies.

More than 90% suspected muscular dystrophy (MD) can be confirmed with multiplex ligation-dependent probe amplification (MLPA) combined with targeted panel, although there are a few that cannot be identified. A total of 312 suspected MD patients were enrolled into the study. The MLPA combined with a targeted myopathy panel were performed. Patients with negative results were subjected to whole exome sequencing (WES), whole genome sequencing (WGS), and/or RNA sequencing (RNA-seq). A total of 275 cases were diagnosed as Duchenne/Becker muscular dystrophy (DMD/BMD) and 20 cases were other types of myopathy or nonmuscular diseases. Six female DMD/BMD patients suffered from varying degrees of typical DMD-like symptoms and 2 others were suspected to be gonadal mosaicism. The systematic application of WES, WGS, and/or RNA-seq highlighted the need for the detection of variants missed by the current standard diagnostic procedures. The identification of female patients and mosaic carriers was crucial to predict the risk of recurrence and allow for optimal genetic counseling.

Bioimpedance analysis of fat free mass and its subcomponents and relative associations with maximal oxygen consumption in facioscapulohumeral dystrophy.

Fat free mass (FFM) is considered the metabolically active component of human body and is positively associated with maximal oxygen uptake ( ). However, FFM is composed of metabolically active and inactive subcomponents whose proportion can vary depending on body composition and clinical condition, possibly affecting such association. Although it is known that in facioscapulohumeral dystrophy (FSHD) peculiar changes in body composition occur, it is unclear whether there are alterations in FFM composition and, if so, whether such alterations affect the association towards compared to healthy subjects (HS). To address this issue, 27 FSHD patients (mean age 37.3; 9 female) and 27 sex and age matched HS, underwent an assessment of by cardiopulmonary exercise tests (CPET) and body composition, with reference to FFM and its subcomponents, by bioimpedance analysis. In between-groups comparison, patients showed lower amounts of body cell mass (BCM) and intracellular water (ICW) which reflect in lower BCM/FFM ratio and higher extracellular to intracellular water ratio (ECW/ICW). Patients' was lower than HS and, even if with lower associative values than HS, correlated with FFM and BCM, while BCM/FFM and ECW/ICW ratios associations were observed only in HS. FSHD patients showed lower amount of BCM and ICW. BCM resulted as the parameter with the highest associative value with VO2max in both groups. Since is associated with functional ability in dystrophic patients, BCM, rather than FFM, could be an additional body composition-based clinical stratification factor.

Investigating therapeutic nonsense suppression in a neurofibromatosis mouse model

Neurofibromatosis type 1 (NF1) is a human genetic disorder caused by variants in the NF1 gene. Plexiform neurofibromas, one of many NF1 manifestations, are benign peripheral nerve sheath tumors occurring in up to 50% of NF1 patients. A substantial fraction of NF1 pathogenetic variants are nonsense mutations, which result in the synthesis of truncated non-functional NF1 protein (neurofibromin). To date, no therapeutics have restored neurofibromin expression or addressed the consequences of this protein's absence in NF1 nonsense mutation patients, but nonsense suppression is a potential approach to the problem. Ataluren is a small molecule drug that has been shown to stimulate functional nonsense codon readthrough in several models of nonsense mutation diseases, as well as in Duchenne muscular dystrophy patients. To test ataluren's potential applicability in nonsense mutation NF1 patients, we evaluated its therapeutic effects using three treatment regimens in a previously established NF1 patient-derived (c.2041C > T; p.Arg681X) nonsense mutation mouse model. Collectively, our experiments indicate that: i) ataluren appeared to slow the growth of neurofibromas and alleviate some paralysis phenotypes, ii) female Nf1-nonsense mutation mice manifested more severe paralysis and neurofibroma phenotypes than male mice, iii) ataluren doses with apparent effectiveness were lower in female mice than in male mice, and iv) age factors also influenced ataluren's effectiveness.

Late-Onset Slowly Progressing Cone/Macular Dystrophy in Patients With the Biallelic Hypomorphic Variant p.Arg1933Ter in RP1.

Homozygous hypomorphic variants of the RP1 gene, including c.5797C>T, p.Arg1933Ter, have traditionally been considered non-pathogenic. This study aimed to elucidate the clinical manifestations of late-onset, slowly progressive cone/macular dystrophy in patients homozygous for p.Arg1933Ter in the RP1 gene. Five patients with biallelic p.Arg1933Ter in RP1 were retrospectively recruited, and their clinical profiles were analyzed. Copy number variation analysis and Alu insertion assessment of genes associated with inherited retinal diseases were conducted. The results of comprehensive ophthalmological examinations, multimodal imaging, and full-field electroretinogram tests were analyzed. No specific sequencing errors or structural variations associated with the clinical phenotypes were identified. Alu element insertion in RP1 was not detected. The mean ± SD age at the first visit was 62.2 ± 9.8 years, with symptoms typically starting between 45 and 50 years of age. Two patients exhibited a mild form of cone/macular dystrophy, characterized by a relatively preserved fundus appearance and blurring of the ellipsoid zone on optical coherence tomography. Three patients had late-onset cone/macular dystrophy with significant atrophy. To our knowledge, this study is the first to report that a homozygous hypomorphic variant of RP1, previously considered non-pathogenic, leads to cone/macular dystrophy. The study introduces novel possibilities suggesting that the homozygous hypomorphic variant of RP1 may be linked to variant pathogenicity.