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- Laforet, P., et al.
(författare)
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Deep morphological analysis of muscle biopsies from type III glycogenesis (GSDIII), debranching enzyme deficiency, revealed stereotyped vacuolar myopathy and autophagy impairment
- 2019
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Ingår i: Acta Neuropathologica Communications. - : Springer Science and Business Media LLC. - 2051-5960. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Glycogen storage disorder type III (GSDIII), or debranching enzyme (GDE) deficiency, is a rare metabolic disorder characterized by variable liver, cardiac, and skeletal muscle involvement. GSDIII manifests with liver symptoms in infancy and muscle involvement during early adulthood. Muscle biopsy is mainly performed in patients diagnosed in adulthood, as routine diagnosis relies on blood or liver GDE analysis, followed by AGL gene sequencing. The GSDIII mouse model recapitulate the clinical phenotype in humans, and a nearly full rescue of muscle function was observed in mice treated with the dual AAV vector expressing the GDE transgene. In order to characterize GSDIII muscle morphological spectrum and identify novel disease markers and pathways, we performed a large international multicentric morphological study on 30 muscle biopsies from GSDIII patients. Autophagy flux studies were performed in human muscle biopsies and muscles from GSDIII mice. The human muscle biopsies revealed a typical and constant vacuolar myopathy, characterized by multiple and variably sized vacuoles filled with PAS-positive material. Using electron microscopy, we confirmed the presence of large nonmembrane bound sarcoplasmic deposits of normally structured glycogen as well as smaller rounded sac structures lined by a continuous double membrane containing only glycogen, corresponding to autophagosomes. A consistent SQSTM1/p62 decrease and beclin-1 increase in human muscle biopsies suggested an enhanced autophagy. Consistent with this, an increase in the lipidated form of LC3, LC3II was found in patients compared to controls. A decrease in SQSTM1/p62 was also found in the GSDIII mouse model. In conclusion, we characterized the morphological phenotype in GSDIII muscle and demonstrated dysfunctional autophagy in GSDIII human samples. These findings suggest that autophagic modulation combined with gene therapy might be considered as a novel treatment for GSDIII.
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- Notarnicola, A., et al.
(författare)
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Autoantibodies against a subunit of mitochondrial respiratory chain complex I in inclusion body myositis
- 2023
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 82, s. 574-574
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Tidskriftsartikel (refereegranskat)abstract
- Background Autoantibodies are found in up to 80% of patients with idiopathic inflammatory myopathies (IIM) and are associated with distinct clinical phenotypes [1]. Autoantibodies targeting cytosolic 5´-nucleotidase 1A (anti-cN1A) are currently the only known serum biomarker for the subgroup inclusion body myositis (IBM) (2), although detected even in other autoimmune diseases.Objectives To identify new autoimmune targets in IIM by antigen bead array assay.Methods In a first cross-sectional exploratory study, 357 antigens representing 268 proteins were incubated with plasma samples from 219 IIM (108 Polymyositis (PM), 80 Dermatomyositis (DM) and 31 IBM) patients, 349 Systemic Lupus Erythematosus (SLE) patients and 306 population controls for screening of IgG reactivity by antigen bead array. All samples were identified in the local biobank of the Rheumatology clinic, Karolinska University Hospital. Interesting results obtained for the IBM subgroup were then validated in an independent larger cohort of 287 patients with IBM followed at nine European rheumatological or neurological centers. IBM serum samples were explored by antigen bead array and results validated by western blot. As controls, serum samples from 30 patients with PM and 30 with DM, HLA-matched with the IBM Swedish cohort, were included. Demographics, laboratory, clinical, and muscle biopsy data of the IBM cohort was retrieved.Results In the exploratory study IgG reactivity towards NADH dehydrogenase 1 α subcomplex 11 (NDUFA11), a subunit of the membrane-bound mitochondrial respiratory chain complex I, was discovered with higher frequency in the IBM (9,7%) than PM (2,8%) and DM samples (2,5%), although the difference was not statistically significant. Anti-NDUFA11 IgG was also found in 2,3% of SLE and 2,6% of population control samples. In the validation study anti-NDUFA11 autoantibodies were detected in 11/287 IBM patients (3,8%), 0/30 PM and 0/30 DM patients. Reactivity against NDUFA11 could be confirmed by western blot (Table 1, Figure 1). The eleven anti-NDUFA11 positive patients showed a trend of lower frequency of wheelchair/walker ever use and higher creatine kinase levels at time of IBM diagnosis compared to the anti-NDUFA11 negative group. Ragged red fibers were significantly more prevalent in anti-NDUFA11 positive than negative patients (p=0.04). Anti-cN1A autoantibodies were detected in 98/287 (34,1%) of IBM, 3/30 (10%) DM and 9/29 (31%) PM patients, p=0.03. Coexistence of anti NDUFA11 and anti-cN1A antibodies was observed in 3 IBM patients.Conclusion Our results reveal a new autoimmune target in the mitochondrial respiratory chain complex I that might be specifically associated with IBM. This is of particular interest as mitochondrial abnormalities are known histological findings in muscle biopsies of IBM patients.References [1]Galindo-Feria AS, Wang G, Lundberg IE. Autoantibodies: Pathogenic or epiphenomenon. Best Pract Res Clin Rheumatol. 2022;36(2):101767.[2]Herbert MK,et al. Disease specificity of autoantibodies to cytosolic 5’-nucleotidase 1A in sporadic inclusion body myositis versus known autoimmune diseases. Ann Rheum Dis. 2016;75(4):696-701.
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- Lilleker, JB, et al.
(författare)
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Cytosolic 5'-nucleotidase 1A autoantibody profile and clinical characteristics in inclusion body myositis
- 2017
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Ingår i: Annals of the rheumatic diseases. - : BMJ. - 1468-2060 .- 0003-4967. ; 76:5, s. 862-868
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Tidskriftsartikel (refereegranskat)abstract
- Autoantibodies directed against cytosolic 5′-nucleotidase 1A have been identified in many patients with inclusion body myositis. This retrospective study investigated the association between anticytosolic 5′-nucleotidase 1A antibody status and clinical, serological and histopathological features to explore the utility of this antibody to identify inclusion body myositis subgroups and to predict prognosis.Materials and methodsData from various European inclusion body myositis registries were pooled. Anticytosolic 5′-nucleotidase 1A status was determined by an established ELISA technique. Cases were stratified according to antibody status and comparisons made. Survival and mobility aid requirement analyses were performed using Kaplan-Meier curves and Cox proportional hazards regression.ResultsData from 311 patients were available for analysis; 102 (33%) had anticytosolic 5′-nucleotidase 1A antibodies. Antibody-positive patients had a higher adjusted mortality risk (HR 1.89, 95% CI 1.11 to 3.21, p=0.019), lower frequency of proximal upper limb weakness at disease onset (8% vs 23%, adjusted OR 0.29, 95% CI 0.12 to 0.68, p=0.005) and an increased prevalence of excess of cytochrome oxidase deficient fibres on muscle biopsy analysis (87% vs 72%, adjusted OR 2.80, 95% CI 1.17 to 6.66, p=0.020), compared with antibody-negative patients.InterpretationDifferences were observed in clinical and histopathological features between anticytosolic 5′-nucleotidase 1A antibody positive and negative patients with inclusion body myositis, and antibody-positive patients had a higher adjusted mortality risk. Stratification of inclusion body myositis by anticytosolic 5′-nucleotidase 1A antibody status may be useful, potentially highlighting a distinct inclusion body myositis subtype with a more severe phenotype.
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