Classification Of Idiopathic Inflammatory Myopathies Research Articles

Biologics for idiopathic inflammatory myopathies.

As treatment of refractory cases of idiopathic inflammatory myopathies (IIMs) has been challenging, there is growing interest in assessing novel biologics that target various pathways implicated in the pathogenesis of IIM. In the largest clinical trial in adult and juvenile IIM assessing the effectiveness of rituximab, the primary outcome was not met but 83% of this refractory group of IIM patients met a predefined definition of improvement and rituximab demonstrated a significant glucocorticoid-sparing effect. Antitumor necrosis factor utility in IIM is generally limited by uncertain efficacy data along with recent reports suggesting their potential for inducing systemic autoimmune disease including IIM. Further research is required to evaluate the role of newer therapies such as tocilizumab (anti-interleukin-6), abatacept (inhibition of T-cell costimulation), sifalimumab (anti-interferonα) and ruxolitinib, (Janus kinase inhibitor) given their biological plausibility and encouraging recent small case series results. Future clinical trials should consider the targeting of biomarkers implicated in the etiopathogenesis of IIM, predictive factors of treatment response, recent revisions in IIM classification criteria, as well as newly developed data-driven response criteria which employ validated core set measures.

P.206 - Anti-HMGCR antibody positive myopathy shows bcl-2-positive lymphocyte follicles

Idiopathic inflammatory myopathies (IIM) are classified in five categories including polymyositis (PM), dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), inclusion body myositis (IBM), and non-specific myositis. Muscle pathologies are required elements for the classification of IIM. In addition to the pathological patterns, more than 15 autoantibodies specific for myositis are already recognized. Recently, Anti-HMG-CoA reductase (HMGCR) antibody is reported to be one of the myositis-specific autoantibodies. HMGCR affects survival of low grade lymphoma by regulating mevalonate pathway. In this study, we aimed to determine the association between anti-HMGCR antibody positive IMNM and a specific morphological phenotype. The muscle biopsy specimens of anti-HMGCR antibody positive IMNM (n = 10), other IMNM (n = 20), PM (n = 13), DM (n = 11), IBM (n = 15), and histologically normal control (n = 5) were examined. These specimens were subjected to routine histochemistry and immunohistochemistry. We also examined skin biopsy specimens from anti-HMGCR antibody positive IMNM (n = 4), other IMNM (n = 4), and DM (n = 8) cases with skin lesions. In anti-HMGCR antibody positive patients, perivascular bcl-2 positive lymphocyte infiltrations were frequently observed in muscle and skin. About 50% of all inflammatory cells were positive for bcl-2. In addition, extranodal lymphocytic follicles are scatterd in 40% of cases with anti-HMGCR antibody. In these follicles, lymophcytes were positive for bcl-2, CD3, CD4, CD8, and CD79a, but not for CD10, CD20. Abnormal lymphocytes were not observed. In IIM except for anti-HMGCR antibody positive IMNM, bcl-2 positive lymphocytes were less than 5% of all inflammatory cells. Perivascular bcl-2 positive lymphocyte infiltration and extranodal lymphocytic follicle might be characteristic findings of anti-HMGCR antibody positive IMNM.

Anti-TIF1-γ antibody and cancer-associated myositis: A clinicohistopathologic study.

We aimed to analyze the clinical and histopathologic features of cancer-associated myositis (CAM) in relation to anti-transcriptional intermediary factor 1 γ antibody (anti-TIF1-γ-Ab), a marker of cancer association. We retrospectively studied 349 patients with idiopathic inflammatory myopathies (IIMs), including 284 patients with pretreatment biopsy samples available. For the classification of IIMs, the European Neuromuscular Center criteria were applied. Patients with CAM with (anti-TIF1-γ-Ab[+] CAM) and without anti-TIF1-γ-Ab (anti-TIF1-γ-Ab[-] CAM) were compared with patients with IIM without cancers within and beyond 3 years of myositis diagnosis. Cancer was detected in 75 patients, of whom 36 (48%) were positive for anti-TIF1-γ-Ab. In anti-TIF1-γ-Ab(+) patients with CAM, cancers were detected within 1 year of myositis diagnosis in 35 (97%) and before 1 year of myositis diagnosis in 1. All the anti-TIF1-γ-Ab(+) patients with CAM satisfied the dermatomyositis (DM) criteria, including 2 possible DM sine dermatitis cases, and were characterized histologically by the presence of perifascicular atrophy, vacuolated fibers (VFs), and dense C5b-9 deposits on capillaries (dC5b-9). In contrast, 39 anti-TIF1-γ-Ab(-) patients with CAM were classified into various subgroups, and characterized by a higher frequency of necrotizing autoimmune myopathy (NAM). Notably, all 7 patients with CAM classified into the NAM subgroup were anti-TIF1-γ-Ab(-) and exhibited no dC5b-9 or VFs. CAM includes clinicohistopathologically heterogeneous disease entities. Among CAM entities, anti-TIF1-γ-Ab(+) CAM has characteristically shown a close temporal association with cancer detection and the histopathologic findings of dC5b-9 and VFs, and CAM with NAM is a subset of anti-TIF1-γ-Ab(-) CAM.

Diagnosis and classification of idiopathic inflammatory myopathies.

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of diseases, collectively termed myositis, sharing symptoms of muscle weakness, fatigue and inflammation. Other organs are frequently involved, supporting the notion that these are systemic inflammatory diseases. The IIMs can be subgrouped into dermatomyositis, polymyositis and inclusion body myositis. The myositis-specific autoantibodies (MSAs) identify other and often more distinct clinical phenotypes, such as the antisynthetase syndrome with antisynthetase autoantibodies and frequent interstitial lung disease and anti-SRP and anti-HMGCR autoantibodies that identify necrotizing myopathy. The MSAs are important both to support myositis diagnosis and to identify subgroups with different patterns of extramuscular organ involvement such as interstitial lung disease. Another cornerstone in the diagnostic procedure is muscle biopsy to identify inflammation and to exclude noninflammatory myopathies. Treatment effect and prognosis vary by subgroup. To develop new and better therapies, validated classification criteria that identify distinct subgroups of myositis are critical. The lack of such criteria was the main rationale for the development of new classification criteria for IIMs, which are summarized in this review; the historical background regarding previous diagnostic and classification criteria is also reviewed. As the IIMs are rare diseases with a prevalence of 10 in 100000 individuals, an international collaboration was essential, as was the interdisciplinary effort including experts in adult and paediatric rheumatology, neurology, dermatology and epidemiology. The new criteria have been developed based on data from more than 1500 patients from 47 centres worldwide and are based on clinically easily available variables.

Idiopathic Inflammatory Myopathies

The idiopathic inflammatory myopathies (IIMs), also known as myositis syndromes, are a collection of heterogeneous disorders that share the common feature of chronic muscle inflammation of unknown cause. These disorders may occur in adults or children and are sometimes associated with other connective tissue disorders and a variety of cancers. A combined clinical, laboratory, and pathologic evaluation is needed to establish the diagnosis of these acquired systemic connective tissue diseases to rule out the many disorders that mimic IIMs. This module reviews the classification of IIMs, including polymyositis, dermatomyositis, inclusion body myositis, myositis associated with other connective tissue diseases and cancer, and antisynthetase syndrome. The epidemiology; etiology, genetics, and environmental factors; pathophysiology and pathogenesis; diagnosis; differential diagnosis; treatment; and prognosis of IIMs are discussed. Tables describe the criteria for polymyositis, dermatomyositis, and inclusion body myositis; well-characterized subgroups of the IIMs in adults and children; presentation of polymyositis; differential diagnosis of muscle weakness or pain; features that assist in discriminating IIMs from other myopathies; goals for managing IIMs; and key factors for achieving adequate corticosteroid response in IIMs. Figures demonstrate skin findings in IIMs, muscle pathology of IIMs, magnetic resonance imaging of three patients with different IIMs, and treatment approaches to the management of myositis patients. This review contains 4 highly rendered figures, 8 tables, and 80 references.

Idiopathic Inflammatory Myopathies

The idiopathic inflammatory myopathies (IIMs), also known as myositis syndromes, are a collection of heterogeneous disorders that share the common feature of chronic muscle inflammation of unknown cause. These disorders may occur in adults or children and are sometimes associated with other connective tissue disorders and a variety of cancers. A combined clinical, laboratory, and pathologic evaluation is needed to establish the diagnosis of these acquired systemic connective tissue diseases to rule out the many disorders that mimic IIMs. This module reviews the classification of IIMs, including polymyositis, dermatomyositis, inclusion body myositis, myositis associated with other connective tissue diseases and cancer, and antisynthetase syndrome. The epidemiology; etiology, genetics, and environmental factors; pathophysiology and pathogenesis; diagnosis; differential diagnosis; treatment; and prognosis of IIMs are discussed. Tables describe the criteria for polymyositis, dermatomyositis, and inclusion body myositis; well-characterized subgroups of the IIMs in adults and children; presentation of polymyositis; differential diagnosis of muscle weakness or pain; features that assist in discriminating IIMs from other myopathies; goals for managing IIMs; and key factors for achieving adequate corticosteroid response in IIMs. Figures demonstrate skin findings in IIMs, muscle pathology of IIMs, magnetic resonance imaging of three patients with different IIMs, and treatment approaches to the management of myositis patients. This review contains 4 highly rendered figures, 8 tables, and 80 references.

Idiopathic Inflammatory Myopathies

The idiopathic inflammatory myopathies (IIMs), also known as myositis syndromes, are a collection of heterogeneous disorders that share the common feature of chronic muscle inflammation of unknown cause. These disorders may occur in adults or children and are sometimes associated with other connective tissue disorders and a variety of cancers. A combined clinical, laboratory, and pathologic evaluation is needed to establish the diagnosis of these acquired systemic connective tissue diseases to rule out the many disorders that mimic IIMs. This module reviews the classification of IIMs, including polymyositis, dermatomyositis, inclusion body myositis, myositis associated with other connective tissue diseases and cancer, and antisynthetase syndrome. The epidemiology; etiology, genetics, and environmental factors; pathophysiology and pathogenesis; diagnosis; differential diagnosis; treatment; and prognosis of IIMs are discussed. Tables describe the criteria for polymyositis, dermatomyositis, and inclusion body myositis; well-characterized subgroups of the IIMs in adults and children; presentation of polymyositis; differential diagnosis of muscle weakness or pain; features that assist in discriminating IIMs from other myopathies; goals for managing IIMs; and key factors for achieving adequate corticosteroid response in IIMs. Figures demonstrate skin findings in IIMs, muscle pathology of IIMs, magnetic resonance imaging of three patients with different IIMs, and treatment approaches to the management of myositis patients. This review contains 4 highly rendered figures, 8 tables, and 80 references.

Diagnostic criteria for idiopathic inflammatory myopathies. Problems of their optimization

The paper deals with the problems of optimizing the diagnostic criteria for idiopathic inflammatory myopathies (IIM), a group of heterogeneous rare autoimmune diseases characterized by inflammatory lesion in the skeletal muscles. The representatives of this group are traditionally considered to be polymyositis (PM), dermatomyositis (DM), and inclusion-body myositis. The authors detail the history of classification criteria for IIM from those proposed by T.A. Medsger et al. (1970) relying on its clinical picture, laboratory data and instrumental findings, as well as the criteria (including the first introduced exclusion ones) elaborated by A. Bohan and J.B. Peter in 1975, which remain fundamental in both clinical practice and researches. The basis for the clinical and serological criteria proposed by Y. Troyanov et al. (2005) for IIM is the identification of myositis-overlap syndromes. The classificational (subtype identification) and therapeutic value of the criteria based on clinical and serological characteristics was supported by the Hungarian investigators A. Vancsa et al. (2010) who investigated the relationship between the clinical and therapeutic characteristics of IIM and positivity for myositis-specific and myositis-associated antibodies. The criteria developed by M.C. Dalakas (1991, 2003) are based on the specific immunopathological features of a histological pattern, which allow the differentiation of DM, PM, and inclusion-body myositis from other myopathic syndromes. The 2004 European Neuromuscular Center (ENMC) criteria first identify necrotizing autoimmune myopathy and nonspecific myositis as individual subtypes. The serological classification of IIM, which is based on the assessment of autoantibodies that play an important role in the pathogenesis of the disease, is of indubitable interest. There is an obvious need for the correct and timely diagnosis of both IIM as a whole and its subtypes in particular, which is complicated by the heterogeneity of the latter. The proposed approaches to diagnosing and classifying IIM have their advantages and disadvantages so that work in this direction is yet to be under way.

SAT0307 Overlap Myositis – the Most Common Form of Autoimmune Myositis

BackgroundAutoimmune myositis (AIM) is a syndrome characterized by proximal muscle weakness, involvement of the cellular and humoral immune systems in skeletal muscle pathology, and presence of autoantibodies (Abs) (myositis-specific (MSAs)...

AB0493 Association between antiviral igm antibodies and myositis autoantibodies in patients with autoimmune myositis in bulgarian population

BackgroundConsiderable evidences indicate that the viruses may be important environmental factors in the pathogenesis of the connective tissue diseases – systemic lupus erythematodes, systemic sclerosis, myositis, etc.1 Viruses activate a...

AB0793 Frequency and relationships between autoantibodies and clinical features in 70 patients with autoimmune myositis in bulgarian population

BackgroundAutoimmune myositis (AIM) is a syndrome characterized by involvement of the cellular and humoral immune systems in skeletal muscle pathology, response to immunotherapies and the presence of autoantibodies (Abs) in...

Immunoregulation in Idiopathic Inflammatory Myopathies: From Dendritic Cells to Immature Regenerating Muscle Cells

Idiopathic inflammatory myopathies (IIM) are a group of chronic muscle disorders of unknown origin that lead to muscle destruction. The original classification of IIM proposed by Bohan and Peter in 1975 including polymyositis (PM) and dermatomyositis (DM) was recently revised with the development of histopathological approaches and the discovery of myositis-specific and myositis-associated antibodies that led to the characterization of new entities. In addition to PM and adult and juvenile DM, these novel classifications distinguish inclusion-body myositis (IBM), immune-mediated necrotizing myopathy, overlap myositis, and cancer-associated myositis1,2. While distinct immunopathogenic mechanisms may occur in each subset of myositis, all IIM share a common inflammatory background associated with clinical, histological, and serological overlap. Several molecular pathways, such as adaptive and innate immune responses, autoimmunity, and nonimmune mechanisms, could influence the pathogenesis of IIM. However, the exact contribution of each one in the development of distinct phenotypes remains unclear. In this issue of The Journal , Gendek-Kubiak and Gendek highlight the contribution of dendritic cells (DC)3. We summarize here recent insights in myositis immunoregulation from DC that are central in the development of adaptive and innate response to nonimmune mechanisms. ### Dendritic cells DC are crucial for the development of adaptive and innate immune responses. DC, subdivided into myeloid DC (mDC) and plasmacytoid DC (pDC), are present in lymphatic and blood systems and peripheral organs. They are equipped with a range of pattern-recognition receptors (PRR) and serve as sentinels of the immune system. Their activation after stimulation of PRR, such as Toll-like receptors (TLR) or C-type lectin receptors (CLR), by microbial components and/or endogenous ligands leads to their maturation and the development of an effector T cell immune response. In muscle biopsies from IIM, both myeloid and plasmacytoid DC have been detected with differences according to IIM subtypes. The DC … Address correspondence to Dr. A. Tournadre, Department of Rheumatology, Gabriel Montpied Hospital, CHU Clermont-Ferrand, 58 rue Montalembert BP69, 63003 Clermont-Ferrand Cedex 1, France. E-mail: atournadre{at}chu-clermontferrand.fr

Distal inflammatory myopathy: Unusual presentation of polymyositis or new entity?

New classification of idiopathic inflammatory myopathy (IIM) defined three major entities, polymyositis (PM), dermatomyositis (DM) and sporadic inclusion body myositis (s-IBM). We report the clinical, electrophysiological and pathological characteristics of three patients with a rare form of IIM not fulfilling the diagnostic criteria for any of these three major entities. The three patients presented with a subacute, distal asymmetrical weakness in upper limbs. Muscle biopsy showed an active myositis, with necrosis and regeneration, T cell infiltrates with invasion of non-necrotic fibers, without rimmed vacuoles, and diffuse major histocompatibility complex-I (MHC-I) immunostaining in muscle fibers. All patients responded to immunosuppressive agents. Seven others cases were identified in the literature. It is important to recognize this atypical presentation as it seems to respond to immunosuppressive agents.

Autoantibodies in idiopathic inflammatory myopathy: an update on clinical and pathophysiological significance

Idiopathic inflammatory myopathy is characterized by the production of autoantibodies to various cellular constituents. These autoantibodies closely correlate with certain clinical conditions and prognosis of disease. This review examines recent progress in myositis-specific autoantibodies, particularly in their clinical significance and pathophysiological roles. During the 1-year review period, novel myositis-specific autoantibodies were identified in clinically amyopathic dermatomyositis (anti-CADM-140 antibody) and malignancy-associated myositis (anti-p155 and anti-p155/p140 antibodies). These new autoantibodies are extremely important because it is thought that myositis-specific autoantibodies are negative in these subgroups, and may enable a new classification of idiopathic inflammatory myopathy. New clinical aspects of other myositis-specific autoantibodies (anti-aminoacyl-tRNA synthetases, anti-signal recognition particles and anti-Mi-2) are also described. The possibility was raised that the high expression of myositis-specific autoantigens in regenerating muscle cells and certain cancers may be involved in initiating and perpetuating the autoimmune response in myositis. Myositis-specific autoantibodies are useful markers for clinical diagnosis, classification and predicting prognosis of idiopathic inflammatory myopathy. To understand the etiopathogenic mechanisms of the disease it is particularly important to elucidate the nature of target autoantigens recognized by these myositis-specific autoantibodies.

Novel Classification of Idiopathic Inflammatory Myopathies Based on Overlap Syndrome Features and Autoantibodies

Our objective was to improve the currently imperfect classifications of idiopathic inflammatory myopathies (IIM). In clinical practice, overlap features are common in IIM. This provided a rationale for positioning overlap clinical features at the core of a new classification system. We conducted a longitudinal study of 100 consecutive adult French Canadian patients with IIM. Clinical and laboratory data were obtained by retrospective chart review. Sera were analyzed for autoantibodies (aAbs) by protein A-assisted immunoprecipitation and double immunodiffusion. Overlap aAbs encompassed aAbs to synthetases, systemic sclerosis-associated aAbs, anti-signal recognition particle (SRP) and anti-nucleoporins. Patients were classified both at IIM diagnosis, based on data at presentation, and at the end of follow-up, based on cumulative findings. Three classifications were used: 1) the Bohan and Peter original classification, 2) a new version of that classification as modified by us, and 3) a novel clinicoserologic classification. As investigators were blinded to aAb results, the modified classification is strictly a clinical classification. Its core concept is the attribution of diagnostic significance to the presence of overlap features, that is, their presence resulted in a diagnosis of overlap myositis (OM). This approach allowed direct comparison with the original Bohan and Peter classification. By integrating aAb results to the modified classification, we also defined the clinicoserologic classification, which allowed to examine the added value of aAbs to diagnostic, therapeutic and prognostic stratification. Whereas polymyositis (PM) was the most common IIM according to the original classification, accounting for 45% of the cohort at diagnosis, its frequency fell to 14% with the modified classification. Conversely, while the frequency of myositis associated with connective tissue disease was 24% according to the original classification, the frequency of OM was 60% when using the modified classification. At last follow-up, the frequency of PM fell further to only 9%, while the frequency of OM rose to 67%. Systemic sclerosis was the most common connective tissue disease associated with IIM, accounting for 42.6% of OM patients and 29% of the cohort. The frequencies of overlap aAbs in the cohort and in OM patients were 48% and 70.5% (n =48/68), respectively. The presence of overlap aAbs at IIM diagnosis identified additional OM patients unrecognized by the modified classification. The sensitivity of the modified classification for OM at diagnosis was 87%, suggesting that clinicians may rely on the modified classification for identification of most OM patients, while awaiting results of aAb assays. The new classifications predicted the response to prednisone and IIM course. Using stringent definitions, IIM was classified as responsive or refractory after an adequate initial corticosteroid therapy, and the disease course as monophasic or chronic after a single adequate trial of prednisone. PM was always chronic and was associated with the highest rate (50%) of refractoriness to initial corticosteroid treatment. Dermatomyositis was almost always chronic (92% rate); however, its responsiveness to initial corticosteroid treatment was high (87%). OM was almost always responsive to corticosteroids (89%-100% rates). When OM patients were divided according to aAb subsets, anti-synthetase, SRP, or nucleoporin aAbs were markers for chronic myositis, whereas aAbs to U1RNP, Pm-Scl, or Ku were markers for monophasic myositis. We conclude that the original Bohan and Peter classification should be abandoned as it leads to misclassification of patients. Much of IIM is composed of OM. The proposed modified and clinicoserologic classifications have diagnostic, prognostic, and therapeutic value.

Anti-Jo-1 Antibodies

Anti-Jo-1 antibody is a myositis specific autoantibody most commonly found in patients with idiopathic inflammatory myopathies (IIM). This antibody is directed against the histidyl-tRNA synthetase which catalyses the binding of the histidine to its cognate tRNA during protein synthesis. It can be considered a specific marker of IIM, predominantly found in 20–30% of patients with PM and in the 60–70% of those with interstitial pulmonary fibrosis. These antibodies are also found in DM, although less frequently than in PM, and are rare in children with PM or DM and in other connective tissue diseases.ELISA, CIE and immunoblotting are highly specific and sensitive techniques for testing anti-Jo-1 antibodies. The detection of this antibody is particularly useful in diagnosis and classification of IIM. Moreover, anti-Jo-1 serum levels strongly correlate with disease activity representing a good marker for disease monitoring.

A new approach to the classification of idiopathic inflammatory myopathy: myositis-specific autoantibodies define useful homogeneous patient groups.

The IIM are a heterogeneous group of systemic rheumatic diseases which share the common features of chronic muscle weakness and mononuclear cell infiltrates in muscle. A number of classification schemes have been proposed for them, but none takes into consideration the marked immunologic, clinical, and genetic heterogeneity of the various clinical groups. We compared the usefulness of myositis-specific autoantibodies (anti-aminoacyl-tRNA synthetases, anti-SRP, anti-Mi-2 and anti-MAS) to the standard clinical categories (polymyositis, dermatomyositis, overlap myositis, cancer-associated myositis, and inclusion body myositis) in predicting clinical signs and symptoms, HLA types, and prognosis in 212 adult IIM patients. Although patients with inclusion body myositis (n = 26) differed in having significantly more asymmetric and distal weakness, falling, and atrophy than other patients, there were few other significant differences among the other clinical groups. In contrast, autoantibody status defined distinct sets of patients and each patient had only 1 myositis-specific autoantibody. Patients with anti-amino-acyl-tRNA synthetase autoantibodies (n = 47), compared to those without these antibodies, had significantly more frequent arthritis, fever, interstitial lung disease, and "mechanic's hands"; HLA-DRw52; higher mean prednisone dose at survey, higher proportion of patients receiving cytotoxic drugs, and higher death rates. Those with anti-signal recognition particle antibodies (n = 7) had increased palpitations; myalgias; DR5, DRw52; severe, refractory disease; and higher death rates. Patients with anti-Mi-2 antibodies (n = 10) had increased "V-sign" and "shawl-sign" rashes, and cuticular overgrowth; DR7 and DRw53; and a good response to therapy. The 2 patients with anti-MAS antibodies were the only ones with alcoholic rhabdomyolysis preceding myositis; both had insulin-dependent diabetes mellitus, and both had HLA-B60, -C3, -DR4, and -DRw53. These findings suggest that myositis-specific autoantibody status is a more useful guide than clinical group in assessing patients with myositis, and that specific associations of immunogenetics, immune responses, and clinical manifestations occur in IIM. Thus the myositis-specific autoantibodies aid in interpreting the diverse symptoms and signs of myositis patients and in predicting their clinical course and prognosis. We propose, therefore, that an adjunct classification of the IIM, based on the myositis-specific autoantibody status, be incorporated into future studies of their epidemiology, etiology, and therapy.