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Nature Reviews. Disease Primers Dec 2021Idiopathic inflammatory myopathies (IIM), also known as myositis, are a heterogeneous group of autoimmune disorders with varying clinical manifestations, treatment...
Idiopathic inflammatory myopathies (IIM), also known as myositis, are a heterogeneous group of autoimmune disorders with varying clinical manifestations, treatment responses and prognoses. Muscle weakness is usually the classical clinical manifestation but other organs can be affected, including the skin, joints, lungs, heart and gastrointestinal tract, and they can even result in the predominant manifestations, supporting that these are systemic inflammatory disorders. Different myositis-specific autoantibodies have been identified and, on the basis of clinical, histopathological and serological features, IIMs can be classified into several subgroups — dermatomyositis (including amyopathic dermatomyositis), antisynthetase syndrome, immune-mediated necrotizing myopathy, inclusion body myositis, polymyositis and overlap myositis. The prognoses, treatment responses and organ manifestations vary among these groups, implicating different pathophysiological mechanisms in each subtype. A deeper understanding of the molecular pathways underlying the pathogenesis and identifying the autoantigens of the immune reactions in these subgroups is crucial to improve outcomes. New, more homogeneous subgroups defined by autoantibodies may help define disease mechanisms, and will also be important in future clinical trials to develop targeted therapies and in identifying biomarkers to guide treatment decisions for the individual patient.
Topics: Humans; Myositis
PubMed: 34857780
DOI: 10.1038/s41572-021-00325-7 -
Annals of the Rheumatic Diseases Jun 2023Inflammatory myopathy or myositis is a heterogeneous family of immune-mediated diseases including dermatomyositis (DM), antisynthetase syndrome (AS), immune-mediated...
OBJECTIVES
Inflammatory myopathy or myositis is a heterogeneous family of immune-mediated diseases including dermatomyositis (DM), antisynthetase syndrome (AS), immune-mediated necrotising myopathy (IMNM) and inclusion body myositis (IBM). Immune checkpoint inhibitors (ICIs) can also cause myositis (ICI-myositis). This study was designed to define gene expression patterns in muscle biopsies from patients with ICI-myositis.
METHODS
Bulk RNA sequencing was performed on 200 muscle biopsies (35 ICI-myositis, 44 DM, 18 AS, 54 IMNM, 16 IBM and 33 normal muscle biopsies) and single nuclei RNA sequencing was performed on 22 muscle biopsies (seven ICI-myositis, four DM, three AS, six IMNM and two IBM).
RESULTS
Unsupervised clustering defined three distinct transcriptomic subsets of ICI-myositis: ICI-DM, ICI-MYO1 and ICI-MYO2. ICI-DM included patients with DM and anti-TIF1γ autoantibodies who, like DM patients, overexpressed type 1 interferon-inducible genes. ICI-MYO1 patients had highly inflammatory muscle biopsies and included all patients that developed coexisting myocarditis. ICI-MYO2 was composed of patients with predominant necrotising pathology and low levels of muscle inflammation. The type 2 interferon pathway was activated both in ICI-DM and ICI-MYO1. Unlike the other types of myositis, all three subsets of ICI-myositis patients overexpressed genes involved in the IL6 pathway.
CONCLUSIONS
We identified three distinct types of ICI-myositis based on transcriptomic analyses. The IL6 pathway was overexpressed in all groups, the type I interferon pathway activation was specific for ICI-DM, the type 2 IFN pathway was overexpressed in both ICI-DM and ICI-MYO1 and only ICI-MYO1 patients developed myocarditis.
Topics: Humans; Immune Checkpoint Inhibitors; Dermatomyositis; Transcriptome; Myocarditis; Interleukin-6; Myositis; Autoimmune Diseases; Myositis, Inclusion Body; Interferons; Muscle, Skeletal
PubMed: 36801811
DOI: 10.1136/ard-2022-223792 -
Acta Myologica : Myopathies and... Dec 2020Giant cell myositis (GCMm) and giant cell myocarditis (GCMc) are two rare autoimmune conditions. Among these, GCMc is a life-threatening disease with a 1-year mortality... (Review)
Review
Giant cell myositis (GCMm) and giant cell myocarditis (GCMc) are two rare autoimmune conditions. Among these, GCMc is a life-threatening disease with a 1-year mortality rate of 70%. Lethal ventricular arrhythmias, rapid evolution to heart failure and sudden death risk makes GCMc an emergency condition. It is thought to be mediated by T-cells and characterized by the presence of myofiber necrosis and giant cells in biopsies. Most commonly co-manifesting conditions with GCMm and/or GCMc are thymoma, myasthenia gravis and orbital myositis, all of which are treatable. As suspicion is the key approach in diagnosis, the physician following patients with thymoma with or without myasthenia gravis and with orbital myositis should always be alert. The fatal nature of GCMc associated with these relatively benign diseases deserves a special emergency attention with prompt institution of combined immunosuppressive treatment and very early inclusion of heart failure teams.
Topics: Giant Cells; Humans; Myocarditis; Myositis
PubMed: 33458585
DOI: 10.36185/2532-1900-033 -
Rheumatic Diseases Clinics of North... Feb 2016Idiopathic inflammatory myopathies (IIMs) involve inflammation of the muscles and are classified by the patterns of presentation and immunohistopathologic features on... (Review)
Review
Idiopathic inflammatory myopathies (IIMs) involve inflammation of the muscles and are classified by the patterns of presentation and immunohistopathologic features on skin and muscle biopsy into 4 categories: dermatomyositis, polymyositis, inclusion body myositis, and immune-mediated necrotizing myopathy. Systemic corticosteroid (CS) treatment is the standard of care for IIM with muscle and organ involvement. The extracutaneous features of systemic sclerosis are frequently treated with CS; however, high doses have been associated with scleroderma renal crisis in high-risk patients. Although CS can be effective first-line agents, their significant side effect profile encourages concomitant treatment with other immunosuppressive medications to enable timely tapering.
Topics: Adrenal Cortex Hormones; Biopsy; Dermatomyositis; Glucocorticoids; Humans; Immunosuppressive Agents; Muscle, Skeletal; Myositis; Myositis, Inclusion Body; Polymyositis; Scleroderma, Systemic; Skin
PubMed: 26611554
DOI: 10.1016/j.rdc.2015.08.011 -
Best Practice & Research. Clinical... Jun 2022Idiopathic inflammatory myopathies (IIM) are heterogeneous autoimmune diseases. There are distinct subgroups, including antisynthetase syndrome, dermatomyositis,... (Review)
Review
Idiopathic inflammatory myopathies (IIM) are heterogeneous autoimmune diseases. There are distinct subgroups, including antisynthetase syndrome, dermatomyositis, polymyositis, immune-mediated necrotizing myopathy, and sporadic inclusion body myositis. In patients with IIM, autoantibodies are present in up to 80% of the patients. These autoantibodies are often characterized as myositis-specific autoantibodies (MSA) or myositis-associated autoantibodies (MAA). The recognition of the importance of autoantibodies, especially MSA, is increasing in recent years. In this chapter, we provide an overview of the MSAs, including some new autoantibodies of interest as they target mainly muscle-specific autoantigen, in clinical classification, the measurement of the disease activity, and a possible role in the pathogenesis in the patients with IIM.
Topics: Autoantibodies; Autoantigens; Autoimmune Diseases; Dermatomyositis; Humans; Myositis; Myositis, Inclusion Body
PubMed: 35810122
DOI: 10.1016/j.berh.2022.101767 -
Autoimmunity Reviews Jun 2023Idiopathic inflammatory myopathies (IIM), even though sharing common clinical manifestations, are characterized by diversified molecular pathogenetic mechanisms which... (Review)
Review
Idiopathic inflammatory myopathies (IIM), even though sharing common clinical manifestations, are characterized by diversified molecular pathogenetic mechanisms which may account for the partial inefficacy of currently used immunomodulatory drugs. In the last decades, the role of interferon (IFN) in IIM has been extensively elucidated thanks to genomic and proteomic studies which have assessed the molecular signature at the level of affected tissues or in peripheral blood across distinct IIM subtypes. A predominant type I IFN response has been shown in dermatomyositis (DM), being especially enhanced in anti-melanoma differentiation-associated gene 5 (MDA5)+ DM, while a type 2 IFN profile characterizes anti-synthetase syndrome (ASyS) and inclusion body myositis (IBM); conversely, a less robust IFN footprint has been defined for immune-mediated necrotizing myopathy (IMNM). Intracellular IFN signaling is mediated by the janus kinase/signal transducer and activator of transcription (JAK/STAT) through dedicated transmembrane receptors and specific cytoplasmic molecular combinations. These results may have therapeutic implications and led to evaluating the efficacy of new targeted drugs such as the recently introduced janus kinase inhibitors (JAKi), currently approved for the treatment of rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. In this review we aim to summarize the most significant evidence of IFN role in IIM pathogenesis and to describe the current state of the art about the ongoing clinical trials on IFN-targeting drugs, with particular focus on JAKi.
Topics: Humans; Proteomics; Myositis; Myositis, Inclusion Body; Autoimmune Diseases; Interferon Type I
PubMed: 37068699
DOI: 10.1016/j.autrev.2023.103334 -
Frontiers in Immunology 2022The idiopathic inflammatory myopathies (IIM) are rare, heterogeneous systemic autoimmune disorders, characterized by inflammation of skeletal muscle and multi-organ... (Review)
Review
The idiopathic inflammatory myopathies (IIM) are rare, heterogeneous systemic autoimmune disorders, characterized by inflammation of skeletal muscle and multi-organ involvement. Studies to identify genetic risk factors and dysregulated gene expression in IIM aim to increase our understanding of disease pathogenesis. Genome-wide association studies have confirmed the HLA region as the most strongly associated region in IIM, with different associations between clinically-defined subgroups. Associated genes are involved in both the innate and adaptive immune response, while identification of variants reported in other autoimmune disorders suggests shared biological pathways. Targeted imputation analysis has identified key associated amino acid residues within HLA molecules that may influence antigen recognition. These amino acids increase risk for specific clinical phenotypes and autoantibody subgroups, and suggest that serology-defined subgroups may be more homogeneous. Recent data support the contribution of rare genetic variation to disease susceptibility in IIM, including mitochondrial DNA variation in sporadic inclusion body myositis and somatic mutations and loss of heterozygosity in cancer-associated myositis. Gene expression studies in skeletal muscle, blood and skin from individuals with IIM has confirmed the role of interferon signalling and other dysregulated pathways, and identified cell-type specific signatures. These dysregulated genes differentiate IIM subgroups and identify potential biomarkers. Here, we review recent genetic studies in IIM, and how these inform our understanding of disease pathogenesis and provide mechanistic insights into biological pathways.
Topics: Autoantibodies; Autoimmune Diseases; Genome-Wide Association Study; Humans; Myositis; Myositis, Inclusion Body
PubMed: 35693792
DOI: 10.3389/fimmu.2022.886290 -
Current Opinion in Rheumatology Nov 2023Imaging techniques such as MRI, ultrasound and PET/computed tomography (CT) have roles in the detection, diagnosis and management of myositis or idiopathic inflammatory... (Review)
Review
PURPOSE OF REVIEW
Imaging techniques such as MRI, ultrasound and PET/computed tomography (CT) have roles in the detection, diagnosis and management of myositis or idiopathic inflammatory myopathy (IIM). Imaging research has also provided valuable knowledge in the understanding of the pathology of IIM. This review explores the latest advancements of these imaging modalities in IIM.
RECENT FINDINGS
Recent advancements in imaging of IIM have seen a shift away from manual and qualitative analysis of the images. Quantitative MRI provides more objective, and potentially more sensitive characterization of fat infiltration and inflammation in muscles. In addition to B-mode ultrasound changes, shearwave elastography offers a new dimension to investigating IIM. PET/CT has the added advantage of including IIM-associated findings such as malignancies.
SUMMARY
It is evident that MRI, ultrasound and PET/CT have important roles in myositis. Continued technological advancement and a quest for more sophisticated applications help drive innovation; this has especially been so of machine learning/deep learning using artificial intelligence and the developing promise of texture analysis.
Topics: Humans; Positron Emission Tomography Computed Tomography; Artificial Intelligence; Myositis; Inflammation; Muscle, Skeletal
PubMed: 37656661
DOI: 10.1097/BOR.0000000000000975 -
Current Opinion in Neurology Oct 2022To discuss recent developments in our understanding of epidemiology, diagnostics, biomarkers, pathology, pathogenesis, outcome measures, and therapeutics in inclusion... (Review)
Review
PURPOSE OF REVIEW
To discuss recent developments in our understanding of epidemiology, diagnostics, biomarkers, pathology, pathogenesis, outcome measures, and therapeutics in inclusion body myositis (IBM).
RECENT FINDINGS
Recent epidemiology data confirms a relatively higher prevalence in the population aged above 50 years and the reduced life expectancy. Association with cancer and other systemic disorders is better defined. The role of magnetic resonance imaging (MRI) and ultrasound in diagnosis as well as in following disease progression has been elucidated. There are new blood and imaging biomarkers that show tremendous promise for diagnosis and as outcome measures in therapeutic trials. Improved understanding of the pathogenesis of the disease will lead to better therapeutic interventions, but also highlights the importance to have sensitive and responsive outcome measures that accurately quantitate change.
SUMMARY
There are exciting new developments in our understanding of IBM which should lead to improved management and therapeutic options.
Topics: Aged; Biomarkers; Disease Progression; Humans; Magnetic Resonance Imaging; Myositis; Myositis, Inclusion Body; Ultrasonography
PubMed: 36069417
DOI: 10.1097/WCO.0000000000001095 -
Arthritis & Rheumatology (Hoboken, N.J.) Feb 2023Idiopathic inflammatory myopathies (IIMs) comprise a heterogeneous group of rare immune-mediated disorders that primarily affect muscles but also lead to dysfunction in... (Review)
Review
Idiopathic inflammatory myopathies (IIMs) comprise a heterogeneous group of rare immune-mediated disorders that primarily affect muscles but also lead to dysfunction in other organs. Five different clinical subphenotypes of IIM have been distinguished: dermatomyositis, polymyositis, inclusion body myositis, antisynthetase syndrome, and immune-mediated necrotizing myopathy. Excess mortality and morbidity associated with IIM are largely attributed to comorbidities, particularly cancer. The risk of malignancy is not equally distributed among IIM groups and is particularly high among patients with dermatomyositis. The cancer risk peaks around 3 years on either side of the IIM diagnosis and remains elevated even 10 years after the onset of the disease. Lung, colorectal, and ovarian neoplasms typically arise before the onset of IIM, whereas melanoma, cervical, oropharyngeal, and nonmelanoma skin cancers usually develop after IIM diagnosis. Given the close temporal proximity between IIM diagnosis and the emergence of malignancy, it has been proposed that IIM could be a consequence rather than a cause of cancer, a process known as a paramalignant phenomenon. Thus, a separate group of IIMs related to paramalignant phenomenon has been distinguished, known as cancer-associated myositis (CAM). Although the relationship between IIM and cancer is widely recognized, the pathophysiology of CAM remains elusive. Given that genetic factors play a role in the development of IIM, dissection of the molecular mechanisms shared between IIM and cancer presents an opportunity to examine the role of autoimmunity in cancer development and progression. In this review, the evidence supporting the contribution of genetics to CAM will be discussed.
Topics: Humans; Dermatomyositis; Myositis; Polymyositis; Myositis, Inclusion Body; Melanoma
PubMed: 36053262
DOI: 10.1002/art.42345