Genetic Dystrophy Research Articles

The proliferation and differentiation of skeletal muscle stem cells are enhanced in a bioreactor.

Skeletal muscle (SKM) is the largest organ in mammalian body and it can repair damages by using the residential myogenic stem cells (MuSC), but this repairing capacity reduces with age and in some genetic muscular dystrophy. Under these circumstances, artificial amplification of autologous MuSC in vitro might be necessary to repair the damaged SKM. The amplification of MuSC is highly dependent on myogenic signals, such as sonic hedgehog (Shh), Wnt3a, and fibroblast growth factors, so formulating an optimum myogenic kit composed of specific myogenic signals might increase the proliferation and differentiation of MuSC efficiently. In this study, various myogenic signals have been tested on C2C12 myoblasts and primary MuSC, and a myogenic kit consists of insulin, lithium chloride, T3, and retinoic acid has been formulated, and we found it significantly increased the fusion index and MHC expression level of both C2C12 and MuSC myotubes. A novel bioreactor providing cyclic stretching (CS) and electrical stimulation (ES) has been fabricated to enhance the myogenic differentiation of both C2C12 and MuSC. We further found that coating the bioreactor substratum with collagen gave the best effect on proliferation and differentiation of MuSC. Furthermore, combining the collagen coating and physical stimuli (CS + ES) in the bioreactor can generate more proliferative primary MuSC cells. Our results have demonstrated that the combination of myogenic kit and bioreactor can provide environment for efficient MuSC proliferation and differentiation. These MuSC and mature myotubes amplified in the bioreactor might be useful for clinical grafting into damaged SKM in the future.

Plasmonic fusion between fibroblasts and skeletal muscle cells for skeletal muscle regeneration.

Normal regeneration of skeletal muscle takes place by the differentiation of muscle-specific stem cells into myoblasts that fuse with existing myofibers for muscle repair. This natural repair mechanism could be ineffective in some cases, for example in patients with genetic muscular dystrophies or massive musculoskeletal injuries that lead to volumetric muscle loss. In this study we utilize the effect of plasmonic cell fusion, i.e. the fusion between cells conjugated by gold nanospheres and irradiated by resonant femtosecond laser pulses, for generating human heterokaryon cells of myoblastic and fibroblastic origin, which further develop into viable striated myotubes. The heterokaryon cells were found to express the myogenic transcription factors MyoD and Myogenin, as well as the Desmin protein that is essential in the formation of sarcomeres, and could be utilized in various therapeutic approaches that involve transplantation of cells or engineered tissue into the damaged muscle.

Dysphagia in Oculopharyngeal Muscular Dystrophy: A Rapid Scoping Review

Purpose: Dysphagia is a common symptom of the rare genetic disease oculopharyngeal muscular dystrophy (OPMD). There are, however, limited resources and recommendations for speech-language pathologists who treat individuals with this condition. This review provides a consolidation of the literature to understand how the components and outcomes of intervention for dysphagia rehabilitation are described and studied in adults with OPMD. Method: A rapid scoping review was completed to identify studies related to dysphagia interventions for adults with OPMD. Data were extracted and analyzed through the lens of the Rehabilitation Treatment Specification System and the International Classification of Functioning, Disability and Health frameworks. Results: A total of eight studies met the review criteria. Six of the studies described rehabilitative interventions, and three focused on outcomes of intervention. Rehabilitation interventions were not described in detail, and a wide variety of outcome measures were used. Conclusions: There is limited research to guide clinical decision-making and intervention for dysphagia rehabilitation in OPMD at this time. Neurodegenerative disorder research may be beneficial in guiding clinical practice. Further research is required to determine the most effective interventions for individuals with OPMD.

NEW GENES AND DISEASES / NGS & RELATED TECHNIQUES: P.328 Neuromuscular disease variant of unknown significance (VUS) resolution using muscle biopsy evaluation: The Iowa experience

Whole exome sequencing and large next generation sequencing panels are being performed frequently in muscular dystrophy (MD) and other neuromuscular disease patients. These tests often reveal numerous variants of unknown significance (VUS) that result in diagnostic uncertainty. A potential means to resolve the pathogenicity of VUS is to evaluate muscle biopsy pathology. The purpose of this study was to investigate the efficacy of our extended muscle biopsy workup in interpreting VUS. Muscle biopsies accessioned at the University of Iowa between November 2015 and December 2019 for the purpose of evaluating VUS were reviewed. The 144 cases included in the study came from 31 states or provinces of the USA and Canada. A total of 91 different genes had a VUS. Individual patients had 1 to 8 VUS, with an average of 1.8 VUS/patient. Thirty-three MD genes had a VUS, 9 of which were dystroglycanopathy-related. Genes causing non-dystrophic myopathies (17) and mitochondrial diseases (9) were also commonly represented. The most frequent VUS involved RYR1 (18) and CAPN3 (15) with COL6A3, DYSF, and TTN having 14 each. Variants in the three genes encoding components of collagen VI made up the largest single disease group with 33 cases. The workup to evaluate VUS was tailored to the individual patient history, muscle biopsy histopathology, and genetic testing data, and included histochemistry, immunostaining, electron microscopy, and/or western blotting. Using these techniques, 33% of cases showed evidence that one of the VUS was likely to be disease-causing. Overall, VUS in CAPN3, DMD, and RYR1 were the most frequently solved as pathogenic (9, 7, and 4 cases, respectively). In 35% of cases, the workup suggested that the VUS were not likely to be pathogenic. Interestingly, in 12% of cases, a genetic MD or other myopathy was suggested that was completely unrelated to the VUS provided. For example, dystrophinopathy was diagnosed in 4 cases, despite molecular genetics reports of VUS in other unrelated genes. In the remaining 20% of cases, the workup was unable to provide guidance about the VUS. Our data suggest that muscle biopsy testing can provide information critical to determining pathogenicity in 80% of neuromuscular disease cases with a VUS.

CRISPR-Cas9 for muscle dystrophies

Muscular dystrophies are a group of rare muscular disorders characterized by weakness and progressive degeneration of the muscle. They are diseases of genetic origin caused by the mutation of one or more genes involved in muscle function. Despite significant progress made in the field of biotherapies in recent years, there is as yet no curative treatment available for these diseases. Studies conducted since the discovery of the CRISPR-Cas9 genomic editing tool have nevertheless led to significant and promising advances in the treatment of muscular dystrophies. CRISPR-Cas9 system allows a stable and permanent edition of the genome and should make it possible to avoid long, partially efficient and repetitive treatments. In this review, we will discuss the latest therapeutic advances obtained using the CRISPR-Cas9 system in genetic muscular dystrophies.

Profiling of the muscle-specific dystroglycan interactome reveals the role of Hippo signaling in muscular dystrophy and age-dependent muscle atrophy

BackgroundDystroglycanopathies are a group of inherited disorders characterized by vast clinical and genetic heterogeneity and caused by abnormal functioning of the ECM receptor dystroglycan (Dg). Remarkably, among many cases of diagnosed dystroglycanopathies, only a small fraction can be linked directly to mutations in Dg or its regulatory enzymes, implying the involvement of other, not-yet-characterized, Dg-regulating factors. To advance disease diagnostics and develop new treatment strategies, new approaches to find dystroglycanopathy-related factors should be considered. The Dg complex is highly evolutionarily conserved; therefore, model genetic organisms provide excellent systems to address this challenge. In particular, Drosophila is amenable to experiments not feasible in any other system, allowing original insights about the functional interactors of the Dg complex.MethodsTo identify new players contributing to dystroglycanopathies, we used Drosophila as a genetic muscular dystrophy model. Using mass spectrometry, we searched for muscle-specific Dg interactors. Next, in silico analyses allowed us to determine their association with diseases and pathological conditions in humans. Using immunohistochemical, biochemical, and genetic interaction approaches followed by the detailed analysis of the muscle tissue architecture, we verified Dg interaction with some of the discovered factors. Analyses of mouse muscles and myocytes were used to test if interactions are conserved in vertebrates.ResultsThe muscle-specific Dg complexome revealed novel components that influence the efficiency of Dg function in the muscles. We identified the closest human homologs for Dg-interacting partners, determined their significant enrichment in disease-associations, and verified some of the newly identified Dg interactions. We found that Dg associates with two components of the mechanosignaling Hippo pathway: the WW domain-containing proteins Kibra and Yorkie. Importantly, this conserved interaction manages adult muscle size and integrity.ConclusionsThe results presented in this study provide a new list of muscle-specific Dg interactors, further analysis of which could aid not only in the diagnosis of muscular dystrophies, but also in the development of new therapeutics. To regulate muscle fitness during aging and disease, Dg associates with Kibra and Yorkie and acts as a transmembrane Hippo signaling receptor that transmits extracellular information to intracellular signaling cascades, regulating muscle gene expression.

Profiling of the Muscle-Specific Dystroglycan Complexome Identifies Novel Muscular Dystrophy Factors

Dystroglycanopathies are a group of inherited disorders characterized by vast clinical and genetic heterogeneity caused by abnormal functioning of the ECM receptor Dystroglycan (Dg). Remarkably, among many cases of diagnosed dystroglycanopathies, only a small fraction can be directly linked to mutations in Dg or its regulatory enzymes, implying the involvement of other, not yet characterized Dg-regulating factors. To identify new players contributing to dystroglycanopathies, we used Drosophila as a genetic muscular dystrophy model. We analyzed the muscle-specific Dg complexome and identified novel Dg interactors, the majority of which are conserved and have human disease-associated homologs. We discovered that components of the Hippo pathway interact physically and genetically with Dg in adult muscles. Dg associates with the WW domain-containing proteins, Kibra and Yorkie, controlling muscle size and integrity. We propose that Dg acts as a transmembrane Hippo signaling receptor that transmits extracellular information to intracellular signaling cascades, regulating muscle gene expression.

Adaptive Immune Response Impairs the Efficacy of Autologous Transplantation of Engineered Stem Cells in Dystrophic Dogs.

Duchenne muscular dystrophy is the most common genetic muscular dystrophy. It is caused by mutations in the dystrophin gene, leading to absence of muscular dystrophin and to progressive degeneration of skeletal muscle. We have demonstrated that the exon skipping method safely and efficiently brings to the expression of a functional dystrophin in dystrophic CD133+ cells injected scid/mdx mice. Golden Retriever muscular dystrophic (GRMD) dogs represent the best preclinical model of Duchenne muscular dystrophy, mimicking the human pathology in genotypic and phenotypic aspects. Here, we assess the capacity of intra-arterial delivered autologous engineered canine CD133+ cells of restoring dystrophin expression in Golden Retriever muscular dystrophy. This is the first demonstration of five-year follow up study, showing initial clinical amelioration followed by stabilization in mild and severe affected Golden Retriever muscular dystrophy dogs. The occurrence of T-cell response in three Golden Retriever muscular dystrophy dogs, consistent with a memory response boosted by the exon skipped-dystrophin protein, suggests an adaptive immune response against dystrophin.

Differential Isoform Expression and Selective Muscle Involvement in Muscular Dystrophies

Despite the expression of the mutated gene in all muscles, selective muscles are involved in genetic muscular dystrophies. Different muscular dystrophies show characteristic patterns of fatty degenerative changes by muscle imaging, even to the extent that the patterns have been used for diagnostic purposes. However, the underlying molecular mechanisms explaining the selective involvement of muscles are not known. To test the hypothesis that different muscles may express variable amounts of different isoforms of muscle genes, we applied a custom-designed exon microarray containing probes for 57 muscle-specific genes to assay the transcriptional profiles in sets of human adult lower limb skeletal muscles. Quantitative real-time PCR and whole transcriptome sequencing were used to further analyze the results. Our results demonstrate significant variations in isoform and gene expression levels in anatomically different muscles. Comparison of the known patterns of selective involvement of certain muscles in two autosomal dominant titinopathies and one autosomal dominant myosinopathy, with the isoform and gene expression results, shows a correlation between the specific muscles involved and significant differences in the level of expression of the affected gene and exons in these same muscles compared with some other selected muscles. Our results suggest that differential expression levels of muscle genes and isoforms are one determinant in the selectivity of muscle involvement in muscular dystrophies.

Role of radiologic imaging in genetic and acquired neuromuscular disorders

Great technologic and clinical progress have been made in the last two decades in identifying genetic defects of several neuromuscular diseases, as Spinal Muscular Atrophy, genetic muscular dystrophies and other genetic myopathies. The diagnosis is usually challenging, due to great variability in genetic abnormalities and clinical phenotypes and the poor specificity of complementary analyses, i.e., serum creatine kinase (CK) and electrophysiology. Muscle biopsy represents the gold standard for the diagnosis of genetic neuromuscular diseases, but clinical imaging of muscle tissue is an important diagnostic tool to identify and quantifyies muscle damage. Radiologic imaging is, indeed, increasingly used as a diagnostic tool to describe patterns and the extent of muscle involvement, thanks to modern techniques that enable to definethe definition of degrees of muscle atrophy and changes in connective tissue. They usually grade the severity of the disease process with greater accuracy than clinical scores. Clinical imaging is more than complementary to perform muscle biopsy, especially as ultrasound scans are often mandatory to identify the muscle to be biopsied. We will here detail and provideWe will herein provide detailed examples of the radiologic methods that can be used in genetic and acquired neuromuscular disorders, stressing pros and cons. Key Words: Muscle Imaging, MRI, CT, genetic muscle disorders, myopathies, dystrophies

Limb-girdle muscular dystrophy in Brazilian children: clinical, histological and molecular characterization

Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of genetic muscular dystrophies, involving 16 autosomal recessive subtypes and eight autosomal dominant subtypes. Autosomal recessive dystrophy is far more common than autosomal dominant dystrophy, particularly in children. The clinical course in this group is characterized by progressive proximal weakness, initially in pelvic and after in shoulder-girdle musculature, varying from very mild to severe degree. Significant overlap of clinical phenotypes, with genetic and clinical heterogeneity, constitutes the rule for this group of diseases. Muscle biopsies are useful for histopathologic and immunolabeling studies, and DNA analysis is the gold standard to establish the specific form of muscular dystrophy. Objectives: The aim of this study was to characterize the clinical, histological and molecular aspects in children with LGMD who attend a big public neuromuscular centre in our country to determine the frequency of different forms. Method: Thirty seven patients were classified as LGMD and included in this analysis. The study period extended from 2009-2012. The female to male ratio was 3:1. The age of onset ranged from two to 13 years, mean 7,5 years. Onset in the first decade was seen in 90%. Results: The initial clinical signs included: frequent falls (22 cases), difficulty in climbing stairs (13 cases), walk on tip toes (2 cases), difficulty in rising from the floor (2 cases) and difficulty on walking (1 case). The serum CK levels were high in all cases. Among the 37 patients, 15 (40,5%) were classified as sarcoglycanopathies (LGMD2C-F), five (13,5%) as dysferlinopathy (LGMD2B), five (13,5%) as calpainopathy (LGMD2A). Mutations in LMNA gene (LGMD1B), FKRP gene (LGMDI) and caveolin gene (LGMD 1C) were identified in two (5,5%), two (5,5%) and one patient (2,5%), respectively. In seven of 37 cases (19%) it was impossible to determine specific diagnosis. Calf hypertrophy, scapular winging and scoliosis were the most characteristic signs in sarcoglycanopathies. In LGMD2I calf hypertrophy is also observed. Atrophy of posterior compartment of thighs is frequent in children with LGMD2B and could suggest the diagnosis. In LGMD2A winging of scapulae and contractures in Achilles tendons were important findings. Muscle biopsy showed a dystrophic pattern in all cases, more intense in sarcoglycanopathies and LGMD2I. Differently from adult’s patients, inflammation changes in dysferlinopaties were uncommon. Lobuled fibers were characteristic changes in calpainopathies in children. Conclusions: A definitive diagnosis among various subtypes of LGMD in children is challenging. Our series was a large study on LGMD in Brazilian children and showed high frequency of sarcoglycanopathies followed by LGMD2A, LGMD2B, LGMD2I, LGMD1B and LGMD1C.

Muscle Disease

On the basis of strong research evidence, Duchenne muscular dystrophy (DMD), the most common severe childhood form of muscular dystrophy, is an X-linked recessive disorder caused by out-of-frame mutations of the dystrophin gene. Thus, it is classified asa dystrophinopathy. The disease onset is before age 5 years. Patients with DMD present with progressive symmetrical limb-girdle muscle weakness and become wheelchair dependent after age 12 years. (2)(3). On the basis of some research evidence,cardiomyopathy and congestive heart failure are usually seen in the late teens in patients with DMD. Progressive scoliosis and respiratory in sufficiency often develop once wheelchair dependency occurs. Respiratory failure and cardiomyopathy are common causes of death, and few survive beyond the third decade of life. (2)(3)(4)(5)(6)(7). On the basis of some research evidence, prednisone at 0.75 mg/kg daily (maximum dose, 40 mg/d) or deflazacort at 0.9 mg/kg daily (maximum dose, 39 mg/d), a derivative of prednisolone (not available in the United States), as a single morning dose is recommended for DMD patients older than 5 years, which may prolong independent walking from a few months to 2 years. (2)(3)(16)(17). Based on some research evidence, treatment with angiotensin-converting enzyme inhibitors, b-blockers, and diuretics has been reported to be beneficial in DMD patients with cardiac abnormalities. (2)(3)(5)(18). Based on expert opinion, children with muscle weakness and increased serum creatine kinase levels may be associated with either genetic or acquired muscle disorders (Tables 1 and 3). (14)(15)

G.P.8 Expression analysis of α-dystroglycan glycosyltransferases in distinct murine muscular dystrophies models

Dystroglycanopathies are genetic muscular dystrophies caused by defects in the glycosylation of α-dystroglycan (DG), an important component of the dystrophin-associated glycoprotein complex (DAG). There are at least six proven or putative glycosyltransferases enzymes, related to muscle diseases, which play a role in O-mannosyl-linked glycosylation of α-DG. In order to address the roles of α-dystroglycan glycosylation in distinct pathways of muscle degeneration and during muscle development we investigated the relative expression of four of them: POMT1, POMGnT1, LARGE and FKRP, in the gastrocnemius muscle from four mouse models for muscular dystrophies: Dmdmdx, Lama2dy2J/J, Largemyd, SJL/J, as compared to normal C57Black6 lineage. The study was done through real time PCR quantification, in three different ages: new born, 3 and 6months of age. In normal mice, a decreased expression with the age was observed for all genes, mainly for Fkrp and Large. In dystrophic lineages, we observed a large variation in the expression of the four glycosylation genes, as compared to normal age-matched mice. In new born, these differences were more significant and an upregulation was observed in Dmdmdx and Largemyd strains, while a downregulation, was detected in Lama2dy2J/J and SJL/J strains. In adult animals, the pattern was more close to normal mice of the same age. Our results suggest that an increase in α-dystroglycan glycosylation occurs during muscle development, and possibly also during the process of muscle regeneration. However, this process is variable in the diverse dystrophic strains. Financial support: FAPESP-CEPID, CNPq-INCT, FINEP, ABDIM.

Childhood Onset of Limb-Girdle Muscular Dystrophy

Limb-girdle muscular dystrophies comprise a rare heterogeneous group of genetic muscular dystrophies, involving 15 autosomal recessive subtypes and seven autosomal dominant subtypes. Autosomal recessive dystrophy is far more common than autosomal dominant dystrophy. Typical clinical features include progressive limb muscle weakness and atrophy (proximal greater than distal), varying from very mild to severe. Significant overlap of clinical phenotypes, with genetic and clinical heterogeneity, constitutes the rule for this group of diseases. Muscle biopsies are useful for histopathologic and immunolabeling studies, and DNA analysis is the gold standard to establish the specific form of muscular dystrophy. A definitive diagnosis among various subtypes is challenging, and the data presented here provide neuromuscular clinicians with additional information to help attain that goal.

Molecular diagnosis of muscular dystrophies, focused on limb girdle muscular dystrophies

Muscular dystrophies include a spectrum of muscle disorders, some of which are phenotypically well characterized. The identification of dystrophin as the causative factor in Duchenne muscular dystrophy has led to the development of molecular genetics and has facilitated the division of muscular dystrophies into distinct groups, among which are the 'limb girdle muscular dystrophies'. This article reviews the methodology to be used in the diagnosis of muscular dystrophies, focused on the groups of limb girdle muscular dystrophies, and the development of new strategies to reach a final molecular diagnosis. A literature review (Medline) from 1985 to the present. Immunohistochemistry and western blotting analyses of the proteins involved in the various forms of muscular dystrophies have permitted a refined pathological approach necessary to conduct genetic studies and to offer appropriate genetic counseling. The application of molecular medicine in genetic muscular dystrophies also brings great hope to the therapeutic management of these patients.

EM.P.3.03 Differential expression of genes involved in muscular degeneration in four dystrophic mouse models

Muscle weakness in muscular dystrophies is the consequence of an imbalance between successive cycles of degeneration and regeneration, with further replacement of the degraded muscle fibers by adipose and connective tissues. One important marker for degeneration is the expression of TGFB1, which is an inflammatory cytokine with a possible role in the stimulation of fibrosis in the dystrophic muscle through the activation of genes related to the expression of collagen. Several mouse models for genetic muscular dystrophies are recognized. Among them, mdx, SJL/J, Lama2dy−2J/J and Largemyd are models for Duchenne, LGMD2B, CMD1A and CMD1D muscular dystrophies, respectively, presenting variable histopathological and clinical findings. High expression of Tgfb1 and alpha 2 subunit of collagen 1 (Col1a2) genes has been found in the mdx mouse. Here we studied the expression of these two genes in three additional mouse models, carrying different defects in muscle proteins, to better understand the involved pathophysiological mechanisms, aiming future therapies. Using Real-Time PCR, we quantified expression of the Tgfb1 and Col1a2 genes in the mdx, SJL/J, Lama2dy−2J/J and Largemyd strains and normal controls. The expression data was compared to histopathological alterations in the respective muscles. Tgfb1 was found to be highly expressed in all four models. However, the Col1a2 gene was upregulated in mdx and SJL/J, both of which showed the most preserved muscle histology, but exhibited lower expression in the more severely affected muscles from Lama2dy−2J/J and Largemyd strains. The results suggest that Tgfb1 gene is activated in the dystrophic process in all types/stages of degeneration while activation of Col1a2 gene possibly occurs in earliest stages of this process. Funding by FAPESP, CNPq-INCT, FINEP, ABDIM.

Inhibition of Prostaglandin D Synthase Suppresses Muscular Necrosis

Duchenne muscular dystrophy is a fatal muscle wasting disease that is characterized by a deficiency in the protein dystrophin. Previously, we reported that the expression of hematopoietic prostaglandin D synthase (HPGDS) appeared in necrotic muscle fibers from patients with either Duchenne muscular dystrophy or polymyositis. HPGDS is responsible for the production of the inflammatory mediator, prostaglandin D(2). In this paper, we validated the hypothesis that HPGDS has a role in the etiology of muscular necrosis. We investigated the expression of HPGDS/ prostaglandin D(2) signaling using two different mouse models of muscle necrosis, that is, bupivacaine-induced muscle necrosis and the mdx mouse, which has a genetic muscular dystrophy. We treated each mouse model with the HPGDS-specific inhibitor, HQL-79, and measured both necrotic muscle volume and selected cytokine mRNA levels. We confirmed that HPGDS expression was induced in necrotic muscle fibers in both bupivacaine-injected muscle and mdx mice. After administration of HQL-79, necrotic muscle volume was significantly decreased in both mouse models. Additionally, mRNA levels of both CD11b and transforming growth factor beta1 were significantly lower in HQL-79-treated mdx mice than in vehicle-treated animals. We also demonstrated that HQL-79 suppressed prostaglandin D(2) production and improved muscle strength in the mdx mouse. Our results show that HPGDS augments inflammation, which is followed by muscle injury. Furthermore, the inhibition of HPGDS ameliorates muscle necrosis even in cases of genetic muscular dystrophy.

Inhibition of prostaglandin D synthase suppresses muscular necrosis

Duchenne muscular dystrophy is a fatal muscle wasting disease that is characterized by a deficiency in the protein dystrophin. Previously, we reported that the expression of hematopoietic prostaglandin D synthase (HPGDS) appeared in necrotic muscle fibers from patients with either Duchenne muscular dystrophy or polymyositis. HPGDS is responsible for the production of the inflammatory mediator, prostaglandin D2. In this paper, we validated the hypothesis that HPGDS has a role in the etiology of muscular necrosis. We investigated the expression of HPGDS/ prostaglandin D2 signaling using two different mouse models of muscle necrosis, that is, bupivacaine-induced muscle necrosis and the mdx mouse, which has a genetic muscular dystrophy. We treated each mouse model with the HPGDS-specific inhibitor, HQL-79, and measured both necrotic muscle volume and selected cytokine mRNA levels. We confirmed that HPGDS expression was induced in necrotic muscle fibers in both bupivacaine-injected muscle and mdx mice. After administration of HQL-79, necrotic muscle volume was significantly decreased in both mouse models. Additionally, mRNA levels of both CD11b and transforming growth factor β1 were significantly lower in HQL-79-treated mdx mice than in vehicle-treated animals. We also demonstrated that HQL-79 suppressed prostaglandin D2 production and improved muscle strength in the mdx mouse. Our results show that HPGDS augments inflammation, which is followed by muscle injury. Furthermore, the inhibition of HPGDS ameliorates muscle necrosis even in cases of genetic muscular dystrophy.

Suffering and Its Amelioration in the Genetic Disease Muscular Dystrophy

Suffering and Its Amelioration in the Genetic Disease Muscular Dystrophy

Is it really myositis? A consideration of the differential diagnosis

The idiopathic inflammatory myopathies are an important and treatable group of disorders. However, the potential toxicity associated with the immune therapeutic regimens used to treat these disorders may be significant; therefore, accurate diagnosis before such treatment is essential. The differential diagnosis is potentially large. Accurate diagnosis usually depends on a combination of careful clinical assessment in conjunction with detailed laboratory investigations. Muscle biopsy remains essential in achieving an accurate diagnosis that will then guide treatment. This review describes the diagnostic approach used. There has been debate over the requirements for an accurate diagnosis of inflammatory myopathy (i.e., polymyositis and dermatomyositis). It is increasingly recognized that there can be clinical and muscle histopathologic overlap between the features of inflammatory myopathies and those of other muscle disorders, in particular, the genetic muscular dystrophies. Pathologic findings of inflammation and major histocompatibility complex upregulation, although typical of inflammatory myopathies, have been shown to occur in some muscular dystrophies, complicating the diagnostic process. Inclusion body myositis is much less responsive to immunotherapy and is now recognized as the most common acquired muscle disease in those older than 50 years of age. It is likely that genetic muscular dystrophies and inclusion body myositis account for some cases of apparently "treatment-resistant" myositis. A thorough clinical assessment, including a detailed family history, complemented by electromyography and creatine kinase measurements, should be undertaken in any patient with presumed idiopathic inflammatory myopathy. In addition, a muscle biopsy remains essential in all cases. A precise tissue diagnosis confirming features of an active inflammatory process should be achieved before immunosuppressive treatment is commenced. An increasing array of immunocytochemical and histioenzymatic stains now allows a full analysis and will help to confirm or exclude virtually all the differential diagnostic possibilities considered in this review. Electron microscopy may also be valuable in selected cases. Close collaboration between clinicians and muscle pathologists is essential in allowing the most accurate interpretation of myopathologic findings in the clinical context.