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BACKGROUND: Inclusion body myositis (IBM) is a progressive myopathy occurring in patients over 45 years of age, with heterogeneous and variable clinical features. This study aimed to determine the influence of autoantibodies, gender, and age of onset on the clinical features of IBM. METHODS: Medical records and muscle histology findings of 570 participants with suspected IBM were reviewed. Various characteristics of patients who met the 2011 ENMC IBM diagnostic criteria were compared based on the presence of anti-cytosolic 5'-nucleotidase 1 A (cN1A) autoantibodies, gender, age of onset, and disease duration. RESULTS: Of the 353 patients who met the criteria, 41.6% were female. The mean age at onset was 64.6 ± 9.3 years, and the mean duration from onset to diagnosis was 5.7 ± 4.7 years. 196 of the 353 patients (55.5%) were positive for anti-cN1A autoantibodies and 157 were negative. Logistic regression showed that patients with anti-cN1A autoantibodies had a higher frequency of finger flexion weakness. Multiple regression showed that patients with later age of onset had shorter disease duration, lower BMI, and lower serum CK levels. Male patients had a higher frequency of onset with finger weakness and female patients had a lower BMI. CONCLUSION: Autoantibodies, gender, age of onset, and disease duration may influence the clinical presentation of IBM, highlighting the need for a precision medicine approach that considers these factors along with the underlying mechanisms of the disease.
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BACKGROUND: Sporadic inclusion body myositis (sIBM) is an intractable muscle disease that frequently affects elderly people. Autoantibodies recognising cytosolic 5'-nucleotidase 1A (cN1A) were found in the sera of patients with sIBM. However, the pathogenic role of the autoantibodies remained unknown. This study investigated the pathogenic properties of the autoantibodies using active cN1A peptides immunisation. METHODS: Wild-type C57BL6 mice were injected with three different mouse cN1A peptides corresponding to the previously reported epitope sequences of human cN1A. After confirming the production of autoantibodies to the corresponding cN1A peptides in each group, changes in body weight, exercise capacity by treadmill test and histological changes in mice injected with cN1A peptides or controls were investigated. RESULTS: Autoantibodies against cN1A were detected in serum samples from mice injected with cN1A peptide. Some groups of mice injected with cN1A peptide showed significant weight loss and decreased motor activity. The number of myofibres with internal nuclei increased in all the peptide-injected groups, with surrounding or invading CD8-positive T cells into myofibres, abnormal protein aggregates and overexpression of p62 and LC3. CONCLUSIONS: Active cN1A peptide immunisation partially reproduced the clinical and histological aspects of sIBM in wild-type mice. The murine model demonstrates the pathogenic properties of anti-cN1A autoantibodies to cause sIBM-like histological changes.
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Miosite de Corpos de Inclusão , Miosite , Humanos , Animais , Camundongos , Idoso , Miosite de Corpos de Inclusão/patologia , Autoanticorpos , 5'-Nucleotidase , Camundongos Endogâmicos C57BL , PeptídeosRESUMO
BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that mainly affects motor neurons in the brain and spinal cord. With the advent of aging societies, the proportion of elderly patients with ALS is expected to increase. METHODS: We retrospectively compared the clinical characteristics at the initial examination of patients with onset of ALS at age 74 years or younger (early onset) and those aged 75 years or older at onset (late-onset) at a single regional ALS diagnostic center in Japan. RESULTS: The phenotype of late-onset ALS differed between males and females, with late-onset females having more bulbar-onset ALS and significantly lower body mass index, late-onset males having more frequent bulbar and respiratory symptoms at the initial examination, and significantly lower forced vital capacity at the initial examination in both groups compared to early onset patients. CONCLUSION: For late-onset patients, maintenance of skeletal muscle mass by early intervention for bulbar and respiratory symptoms may be useful for prolonging survival; however, a prospective analysis is warranted.
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Esclerose Lateral Amiotrófica , Doenças Neurodegenerativas , Masculino , Feminino , Humanos , Esclerose Lateral Amiotrófica/diagnóstico , Esclerose Lateral Amiotrófica/epidemiologia , Estudos Retrospectivos , Fatores Sexuais , Neurônios MotoresRESUMO
AIMS: In idiopathic inflammatory myopathies (IIM), disease activity is difficult to assess, and IIM may induce severe muscle damage, especially in immune-mediated necrotising myopathies (IMNM) and inclusion body myositis (IBM). We hypothesise that myostatin, a negative regulator of muscle mass, could be a new biomarker of disease activity and/or muscle damage. METHODS: Prospective assessment of myostatin protein level in 447 IIM serum samples (dermatomyositis [DM], n = 157; IBM, n = 72; IMNM, n = 125; and antisynthetase syndrome [ASyS], n = 93) and 59 healthy donors (HD) was performed by ELISA. A gene transcript analysis was also carried out on 18 IIM muscle biopsies and six controls to analyse myostatin and myostatin pathway-related gene expression. RESULTS: IIM patients had lower myostatin circulating protein levels and gene expression compared to HD (2379 [1490; 3678] pg/ml vs 4281 [3169; 5787] pg/ml; p < 0.0001 and log2FC = -1.83; p = 0.0005, respectively). Myostatin-related gene expression varied accordingly. Based on the Physician Global Assessment, inactive IIM patients showed higher myostatin levels than active ones. This was the case for all IIM subgroups, except IMNM where low myostatin levels were maintained (2186 [1235; 3815] vs 2349 [1518; 3922] pg/ml; p = 0.4). CONCLUSIONS: Myostatin protein and RNA levels are decreased in all IIM patients, and protein levels correlate with disease activity. Inactive ASyS and DM patients have higher myostatin levels than active patients. Myostatin could be a marker of disease activity in these subgroups. However, IMNM patients do not have significant increase in myostatin levels after disease remission. This may highlight a new pathological disease mechanism in IMNM patients.
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Dermatomiosite , Miosite de Corpos de Inclusão , Miosite , Humanos , Dermatomiosite/patologia , Miostatina , Estudos Prospectivos , Miosite/patologia , Miosite de Corpos de Inclusão/patologiaRESUMO
Inclusion body myositis (IBM) is a refractory muscle disease characterized by inflammatory and degenerative features in myofibers. Macroglossia is common in systemic amyloid light chain amyloidosis; however, no reports have been published on patients with IBM. We encountered a female patient with clinicopathologically defined IBM who exhibited relatively rapid progression of dysphagia, gait disturbance, and macroglossia. Muscle biopsy demonstrated endomysial mononuclear inflammatory infiltrates, fiber necrosis and regeneration with rimmed vacuoles, and sarcoplasmic inclusions of p62. Tongue biopsy demonstrated fiber degeneration with fatty replacement and fibrosis, nonnecrotic fibers surrounded and invaded by mononuclear cells, and sarcoplasmic dotlike inclusions of p62. Based on the parotid gland, lip, and muscle biopsy, she was diagnosed as having IBM with Sjögren's syndrome. She was treated with steroid pulse and intravenous immunoglobulin therapy followed by oral administration of prednisolone, which resulted in temporary clinical improvement. Macroglossia might be an indicator of immunotherapy effectiveness.
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Macroglossia , Miosite de Corpos de Inclusão , Humanos , Feminino , Miosite de Corpos de Inclusão/complicações , Miosite de Corpos de Inclusão/diagnóstico , Miosite de Corpos de Inclusão/patologia , Miocárdio/patologiaRESUMO
We aimed to establish a novel murine model of autoimmune autonomic ganglionopathy (AAG), which represents autoimmune dysautonomia, associated with MHC class II to understand its pathomechanism and the pathogenicity of nicotinic acetylcholine receptor (nAChR) antibodies. The amino acid sequence of the mouse nAChRα3 protein was analyzed using an epitope prediction tool to predict the possible MHC class II binding mouse nAChRα3 peptides. We focused on two nAChRα3 peptides in the extracellular region, and experimental AAG (EAAG) was induced by immunization of C57BL/6 mice with these two different peptides. EAAG mice were examined both physiologically and histologically. Mice with EAAG generated nAChRα3 antibodies and exhibited autonomic dysfunction, including reduced heart rate, excessive fluctuations in systolic blood pressure, and intestinal transit slowing. Additionally, we observed skin lesions, such as alopecia and skin ulcers, in immunized mice. Neuronal cell density in the sympathetic cervical ganglia in immunized mice was significantly lower than that in control mice at the light microscopic level. We interpreted that active immunization of mice with nAChRα3 peptides causes autonomic dysfunction similar to human AAG induced by an antibody-mediated mechanism. We suggested a mechanism by which different HLA class II molecules might preferentially affect the nAChR-specific immune response, thus controlling diversification of the autoantibody response. Our novel murine model mimics AAG in humans and provides a useful tool to investigate its pathomechanism.
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â¢We describe the first case of binasal hemianopia due to bilateral optic perineuritis.â¢Bilateral optic perineuritis should be considered as a causative disease of binasal hemianopia.â¢Early diagnosis of optic perineuritis is crucial to avoid irreversible visual impairment.
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The classification of idiopathic inflammatory myopathies (IIM) is based on clinical, serological and histological criteria. The identification of myositis-specific antibodies has helped to define more homogeneous groups of myositis into four dominant subsets: dermatomyositis (DM), antisynthetase syndrome (ASyS), sporadic inclusion body myositis (sIBM) and immune-mediated necrotising myopathy (IMNM). sIBM and IMNM patients present predominantly with muscle involvement, whereas DM and ASyS patients present additionally with other extramuscular features, such as skin, lung and joints manifestations. Moreover, the pathophysiological mechanisms are distinct between each myositis subsets. Recently, interferon (IFN) pathways have been identified as key players implicated in the pathophysiology of myositis. In DM, the key role of IFN, especially type I IFN, has been supported by the identification of an IFN signature in muscle, blood and skin of DM patients. In addition, DM-specific antibodies are targeting antigens involved in the IFN signalling pathways. The pathogenicity of type I IFN has been demonstrated by the identification of mutations in the IFN pathways leading to genetic diseases, the monogenic interferonopathies. This constitutive activation of IFN signalling pathways induces systemic manifestations such as interstitial lung disease, myositis and skin rashes. Since DM patients share similar features in the context of an acquired activation of the IFN signalling pathways, we may extend underlying concepts of monogenic diseases to acquired interferonopathy such as DM. Conversely, in ASyS, available data suggest a role of type II IFN in blood, muscle and lung. Indeed, transcriptomic analyses highlighted a type II IFN gene expression in ASyS muscle tissue. In sIBM, type II IFN appears to be an important cytokine involved in muscle inflammation mechanisms and potentially linked to myodegenerative features. For IMNM, currently published data are scarce, suggesting a minor implication of type II IFN. This review highlights the involvement of different IFN subtypes and their specific molecular mechanisms in each myositis subset.
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Interferon Tipo I/metabolismo , Músculo Esquelético/patologia , Miosite/patologia , Expressão Gênica/fisiologia , Perfilação da Expressão Gênica/métodos , Humanos , Miosite/metabolismoRESUMO
OBJECTIVE: Patients with acquired autonomic dysfunction may have antibodies specific to the ganglionic nicotinic acetylcholine receptor (gAChR). However, the clinical features of children and adolescents with acquired autonomic dysfunction (AAD) remain unclear. This study aimed to determine the clinical features of pediatric patients with acquired autonomic dysfunction. METHODS: This study retrospectively examined a series of patients of AAD with serum gAChR antibodies who were referred to our laboratory for antibody testing between January 2012 and April 2019. The study included 200 patients (<20 years, 20 cases; ≥20 years, 175 cases) with clinical features of AAD. RESULTS: Upon comparing pediatric and adult patients, we found that antecedent infection and autonomic symptoms at onset with gastrointestinal symptoms occurred more frequently in children with AAD. We confirmed that four children (20.0%) met the diagnostic criteria for postural orthostatic tachycardia syndrome (POTS). A significantly higher number of children than adults had POTS (P = 0.002). In addition, upper GI dysfunction was more prevalent in children than in adults (P = 0.042). In particular, nausea and vomiting occurred in 60.0% of children with AAD and in 21.1% of adults (P < 0.001). The frequency of paralytic ileus was significantly higher in children with AAD (20.0%) relative to adults (6.3%) (P = 0.030). Regarding extra-autonomic manifestations, encephalopathy was more frequent in children (15.0%) than in adults (1.1%) (P < 0.001). INTERPRETATION: Pediatric AAD patients have their own clinical characteristics, and these features may be unique to children and adolescents.
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Autoanticorpos/sangue , Doenças Autoimunes do Sistema Nervoso , Disautonomias Primárias , Receptores Nicotínicos/imunologia , Adolescente , Adulto , Idoso , Doenças Autoimunes do Sistema Nervoso/sangue , Doenças Autoimunes do Sistema Nervoso/diagnóstico , Doenças Autoimunes do Sistema Nervoso/imunologia , Doenças Autoimunes do Sistema Nervoso/fisiopatologia , Criança , Humanos , Japão , Pessoa de Meia-Idade , Síndrome da Taquicardia Postural Ortostática/sangue , Síndrome da Taquicardia Postural Ortostática/diagnóstico , Síndrome da Taquicardia Postural Ortostática/imunologia , Síndrome da Taquicardia Postural Ortostática/fisiopatologia , Disautonomias Primárias/sangue , Disautonomias Primárias/diagnóstico , Disautonomias Primárias/imunologia , Disautonomias Primárias/fisiopatologia , Estudos Retrospectivos , Adulto JovemAssuntos
Albuterol/uso terapêutico , Mutação/genética , Síndromes Miastênicas Congênitas/tratamento farmacológico , Receptores Colinérgicos/genética , Adulto , Humanos , Masculino , Síndromes Miastênicas Congênitas/diagnóstico , Síndromes Miastênicas Congênitas/genética , Junção Neuromuscular/efeitos dos fármacos , Junção Neuromuscular/genética , Receptores Colinérgicos/efeitos dos fármacosAssuntos
Esclerose Lateral Amiotrófica/patologia , Fibras Musculares Esqueléticas/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Esclerose Lateral Amiotrófica/sangue , Esclerose Lateral Amiotrófica/fisiopatologia , Creatina Quinase/sangue , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/patologia , Estudos Retrospectivos , Capacidade VitalRESUMO
Muscle biopsy can be used to confirm the diagnosis of neuromuscular diseases. However, it is unclear whether antibiotic prophylaxis prior to muscle biopsy is needed to prevent surgical site infection (SSI). We are conducting a phase 2, single-center, open-labeled, prospective randomized trial to clarify the need for antibiotic prophylaxis in patients at low risk for SSI undergoing muscle biopsy. Patients will be randomized to an antibiotic prophylaxis group or a control group, and the incidence of SSI will be compared between the groups. Our findings will clarify the need for antibiotic prophylaxis in this patient population.
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Antibacterianos/administração & dosagem , Antibioticoprofilaxia/métodos , Biópsia/efeitos adversos , Cefazolina/administração & dosagem , Infecção da Ferida Cirúrgica/prevenção & controle , Ensaios Clínicos Fase II como Assunto , Humanos , Músculo Esquelético/patologia , Neurologia , Estudos Prospectivos , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
The clinical importance of autoantibodies against the ganglionic acetylcholine receptor (gAChR) remains to be fully elucidated. We aimed to identify the clinical characteristics of autoimmune autonomic ganglionopathy (AAG) in patients with gAChR autoantibodies. For this cohort investigation, serum samples were obtained from patients with AAG between 2012 and 2018 in Japan. We measured the levels of autoantibodies against gAChRα3 and gAChRß4 and evaluated clinical features, as well as assessing the laboratory investigation results among the included patients. A total of 179 patients tested positive for antibodies, including 116 gAChRα3-positive, 13 gAChRß4-positive, and 50 double antibody-positive patients. Seropositive AAG patients exhibited widespread autonomic dysfunction. Extra-autonomic manifestations including sensory disturbance, central nervous system involvement, endocrine disorders, autoimmune diseases, and tumours were present in 118 patients (83%). We observed significant differences in the frequencies of several autonomic and extra-autonomic symptoms among the three groups. Our 123I-metaiodobenzylguanidine myocardial scintigraphy analysis of the entire cohort revealed that the heart-to-mediastinum ratio had decreased by 80%. The present study is the first to demonstrate that patients with AAG who are seropositive for anti-gAChRß4 autoantibodies exhibit unique autonomic and extra-autonomic signs. Decreased cardiac uptake occurred in most cases, indicating that 123I- metaiodobenzylguanidine myocardial scintigraphy may be useful for monitoring AAG. Therefore, our findings indicate that gAChRα3 and gAChRß4 autoantibodies cause functional changes in postganglionic fibres in the autonomic nervous system and extra-autonomic manifestations in seropositive patients with AAG.
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Doenças Autoimunes/diagnóstico , Doenças Autoimunes/imunologia , Autoimunidade , Doenças do Sistema Nervoso Autônomo/diagnóstico , Doenças do Sistema Nervoso Autônomo/imunologia , Gânglios Autônomos/imunologia , Receptores Colinérgicos/imunologia , Autoanticorpos/sangue , Autoanticorpos/imunologia , Autoantígenos/imunologia , Doenças Autoimunes/sangue , Doenças do Sistema Nervoso Autônomo/sangue , Biomarcadores , Humanos , Japão , Imagem de Perfusão do Miocárdio , FenótipoRESUMO
BACKGROUND: Hereditary motor and sensory neuropathy with proximal dominant involvement (HMSN-P) is characterized by adult onset, a slowly progressive course and autosomal dominant inheritance. It remains unclear whether myopathic changes occur histopathologically. METHODS: We encountered 2 patients in a family with a heterozygous p.P285L mutation in TRK-fused gene (TFG), which is known to cause HMSN-P. The affected individuals developed proximal-dominant muscle weakness in their 40s, which slowly progressed to a motor neuron disease-like phenotype. RESULTS: Muscle biopsy showed myopathic pathology including fiber size variability, increased internal nuclei, fiber splitting, and core-like structures, associated with neurogenic changes: large groups of atrophic fibers and fiber type-grouping. Immunohistochemistry revealed sarcoplasmic aggregates of TFG, TDP-43, and p62 without congophilic material. CONCLUSIONS: The present study demonstrates myopathic changes in HMSN-P. Although the mechanisms underlying the skeletal muscle involvement remain to be elucidated, immunohistochemistry suggests that abnormal protein aggregation may be involved in the myopathic pathology.
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Neuropatia Hereditária Motora e Sensorial/patologia , Fibras Musculares Esqueléticas/patologia , Músculo Esquelético/patologia , Potenciais de Ação , Proteínas de Ligação a DNA/metabolismo , Feminino , Imunofluorescência , Neuropatia Hereditária Motora e Sensorial/diagnóstico por imagem , Neuropatia Hereditária Motora e Sensorial/genética , Neuropatia Hereditária Motora e Sensorial/fisiopatologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/diagnóstico por imagem , Atrofia Muscular/patologia , Condução Nervosa , Linhagem , Proteínas/genética , Proteínas de Ligação a RNA/metabolismo , Retículo Sarcoplasmático/metabolismo , IrmãosRESUMO
Sporadic inclusion body myositis (sIBM) is the most commonly acquired myopathy in middle-aged and elderly people. The muscle histology is characterized by both inflammation and degeneration, including sarcoplasmic aggregation of TDP-43. Cylindromatosis (CYLD) is a deubiquitinating enzyme that targets Lys63-linked ubiquitin chains and negatively regulates signal transduction pathways, such as NF-κB signalling pathways. We examined localization of CYLD as well as phosphorylated TDP-43, phosphorylated p62, and Lys63-linked ubiquitin in muscle tissues of sIBM patients and muscle-specific wild-type TDP-43 transgenic (TDP-43 TG) mice. We investigated whether overexpression of CYLD can affect muscle toxicity in the cell models treated by endoplasmic reticulum (ER) stress inducers tunicamycin and thapsigargin. CYLD expressed with phosphorylated TDP-43, phosphorylated p62, and Lys63-linked ubiquitin in the nuclear and perinuclear regions of muscle fibres of wild-type TDP-43 TG mice and the degenerative myofibres of sIBM patients with rimmed vacuoles and endomysial cellular infiltration. Although expression levels of CYLD decreased and cell viability was reduced in cells treated with ER stress inducers, wild-type CYLD, but not the catalytic mutant, substantially improved cell viability based on the deubiquitinase activity. Dysregulation of CYLD may reinforce myodegeneration in the pathophysiology of sIBM by attenuating autophagic clearance of protein aggregates. Regulating CYLD in muscle fibres might serve as a novel therapeutic strategy for sIBM treatment.
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Enzima Desubiquitinante CYLD/fisiologia , Miosite de Corpos de Inclusão/fisiopatologia , Idoso , Animais , Enzima Desubiquitinante CYLD/genética , Estresse do Retículo Endoplasmático , Humanos , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Miosite de Corpos de Inclusão/metabolismo , Fosforilação , Proteômica , Ubiquitina/metabolismo , Vacúolos/metabolismoRESUMO
Mutations in the Matrin 3 (MATR3) gene have been identified as a cause of amyotrophic lateral sclerosis (ALS) or vocal cord and pharyngeal weakness with distal myopathy (VCPDM). This study investigated the mechanism by which mutant MATR3 causes multisystem proteinopathy (MSP) including ALS and VCPDM. We first analyzed the muscle pathology of C57BL/6 mice injected with adeno-associated viruses expressing human WT or mutant (S85C) MATR3. We next generated transgenic mice that overexpress mutant (S85C) MATR3, driven by the CMV early enhancer/chicken ß-actin promoter, and evaluated their clinicopathological features. Intramuscular injection of viruses expressing WT and mutant MATR3 induced similar myogenic changes, including smaller myofibers with internal nuclei, and upregulated p62 and LC3-II. Mutant MATR3 transgenic mice showed decreased body weight and lower motor activity. Muscle histology demonstrated myopathic changes including fiber-size variation, internal nuclei and rimmed vacuoles. Spinal cord histology showed a reduced number of motor neurons, and activation of microglia and astrocytes. Comprehensive proteomic analyses of muscle demonstrated upregulation of proteins related to chaperones, stress response, protein degradation, and nuclear function. Overexpression of WT and mutant MATR3 similarly caused myotoxicity, recapitulating the clinicopathological features of MSP. These models will be helpful for analyzing MSP pathogenesis and for understanding the function of MATR3. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Esclerose Lateral Amiotrófica/genética , Miopatias Distais/genética , Doenças da Laringe/genética , Músculo Esquelético/metabolismo , Mutação , Proteínas Associadas à Matriz Nuclear/genética , Doenças Faríngeas/genética , Proteínas de Ligação a RNA/genética , Medula Espinal/metabolismo , Esclerose Lateral Amiotrófica/metabolismo , Esclerose Lateral Amiotrófica/patologia , Esclerose Lateral Amiotrófica/fisiopatologia , Animais , Dependovirus/genética , Modelos Animais de Doenças , Miopatias Distais/metabolismo , Miopatias Distais/patologia , Miopatias Distais/fisiopatologia , Análise da Marcha , Técnicas de Transferência de Genes , Predisposição Genética para Doença , Humanos , Doenças da Laringe/metabolismo , Doenças da Laringe/patologia , Doenças da Laringe/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Associadas aos Microtúbulos/metabolismo , Atividade Motora , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Proteínas Associadas à Matriz Nuclear/metabolismo , Doenças Faríngeas/metabolismo , Doenças Faríngeas/patologia , Doenças Faríngeas/fisiopatologia , Proteínas de Ligação a RNA/metabolismo , Teste de Desempenho do Rota-Rod , Proteína Sequestossoma-1/metabolismo , Medula Espinal/patologia , Medula Espinal/fisiopatologia , Redução de PesoRESUMO
Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder characterized by ptosis, dysphagia, and weakness of proximal limbs. OPMD is caused by the expansion of polyalanine in poly(A)-binding protein, nuclear 1 (PABPN1). Although mitochondrial abnormality has been proposed as the possible etiology, the molecular pathogenesis is still poorly understood. The aim of the study was to specify the mechanism by which expanded PABPN1 causes mitochondrial dysfunction in OPMD. We evaluated whether transgenic mouse model of OPMD, by expressing expanded PABPN1, indeed causes mitochondrial abnormality associated with muscle degeneration. We also investigated the mechanism by which expanded PABPN1 would cause mitochondrial dysfunction in the mouse and cell models of OPMD. Mitochondrial localization of PABPN1 was observed in the muscle fibers of patients with OPMD. Moreover, abnormal accumulation of PABPN1 on the inner membrane of mitochondria and reduced expression of OXPHOS complexes were detected in the muscle fibers of the transgenic mice expressing expanded human PABPN1 with a 13-alanine stretch. In cells expressing PABPN1 with a 10-alanine or 18-alanine stretch, both types of PABPN1 accumulated in the mitochondria and interacted with TIM23 mitochondrial protein import complex, but PABPN1 with 18-alanine stretch decreased the cell viability and aggresome formation. We proposed that the abnormal accumulation of expanded PABPN1 in mitochondria may be associated with mitochondrial abnormality in OPMD.
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Mitocôndrias Musculares/metabolismo , Distrofia Muscular Oculofaríngea/genética , Distrofia Muscular Oculofaríngea/metabolismo , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Proteína I de Ligação a Poli(A)/genética , Proteína I de Ligação a Poli(A)/metabolismo , Expansão das Repetições de Trinucleotídeos , Animais , Estudos de Casos e Controles , Sobrevivência Celular , Modelos Animais de Doenças , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HEK293 , Humanos , Camundongos , Camundongos Transgênicos , Microscopia Eletrônica de Transmissão , Mitocôndrias Musculares/patologia , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteínas do Complexo de Importação de Proteína Precursora Mitocondrial , Modelos Biológicos , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Distrofia Muscular Oculofaríngea/patologia , Proteínas Mutantes/química , Fosforilação Oxidativa , Proteína I de Ligação a Poli(A)/química , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMO
Sporadic inclusion body myositis (sIBM) is a chronic and progressive inflammatory myopathy that is the commonest among population over 50s. Recently, autoantibodies against cytosolic 5'-nucleotidase 1A (cN1A) have been identified in plasma and serum samples from patients with sIBM. So far, various methods have been established to detect the anti-cN1A autoantibodies, which showed a clinical utility of detection of the autoantibodies in the diagnosis of sIBM. Here we describe a novel cell-based assay for detection of the autoantibodies, which seems equivalent in sensitivity and better in specificity for the diagnosis of sIBM, compared with the previous methods.
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5'-Nucleotidase/imunologia , Autoanticorpos/análise , Citosol/enzimologia , Imunofluorescência/métodos , Animais , Células COS , Chlorocebus aethiops , Proteínas de Fluorescência Verde/metabolismo , HumanosRESUMO
PURPOSE: The diagnostic rate for Mendelian diseases by exome sequencing (ES) is typically 20-40%. The low rate is partly because ES misses deep-intronic or synonymous variants leading to aberrant splicing. In this study, we aimed to apply RNA sequencing (RNA-seq) to efficiently detect the aberrant splicings and their related variants. METHODS: Aberrant splicing in biopsied muscles from six nemaline myopathy (NM) cases unresolved by ES were analyzed with RNA-seq. Variants related to detected aberrant splicing events were analyzed with Sanger sequencing. Detected variants were screened in NM patients unresolved by ES. RESULTS: We identified a novel deep-intronic NEB pathogenic variant, c.1569+339A>G in one case, and another novel synonymous NEB pathogenic variant, c.24684G>C (p.Ser8228Ser) in three cases. The c.24684G>C variant was observed to be the most frequent among all NEB pathogenic variants in normal Japanese populations with a frequency of 1 in 178 (20 alleles in 3552 individuals), but was previously unrecognized. Expanded screening of the variant identified it in a further four previously unsolved nemaline myopathy cases. CONCLUSION: These results indicated that RNA-seq may be able to solve a large proportion of previously undiagnosed muscle diseases.