Genome-wide association studies (GWASs) have been successful at finding associations between genetic variants and human traits, including the immune-mediated diseases (IMDs). However, the requirement of large sample sizes for discovery poses a challenge for learning about less common diseases, where increasing volunteer numbers might not be feasible. An example of this is myositis (or idiopathic inflammatory myopathies [IIM]s), a group of rare, heterogeneous autoimmune diseases affecting skeletal muscle and other organs, severely impairing life quality. Here, we applied a feature engineering method to borrow information from larger IMD GWASs to find new genetic associations with IIM and its subgroups. Combining this approach with two clustering methods, we found 17 IMDs genetically close to IIM, including some common comorbid conditions, such as systemic sclerosis and Sjögren's syndrome, as well as hypo- and hyperthyroidism. All IIM subtypes were genetically similar within this framework. Next, we colocalized IIM signals that overlapped IMD signals, and found seven potentially novel myositis associations mapped to immune-related genes, including BLK, IRF5/TNPO3, and ITK/HAVCR2, implicating a role for both B and T cells in IIM. This work proposes a new paradigm of genetic discovery in rarer diseases by leveraging information from more common IMD, and can be expanded to other conditions and traits beyond IMD.

• MeSH
• Autoimmune Diseases genetics   immunology   MeSH
• Genome-Wide Association Study * MeSH
• Genetic Predisposition to Disease * MeSH
• Polymorphism, Single Nucleotide MeSH
• Humans MeSH
• Myositis * genetics   immunology   MeSH
• Immune System Diseases genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH

OBJECTIVE: To study the trajectories of changes in damage over time and explore associations with autoantibody defined subgroups using a large international cohort of patients with idiopathic inflammatory myopathies (IIM). METHODS: Data from the MYONET registry, including patients who were tested for autoantibodies and had at least one assessment of damage using the Myositis Damage Index (MDI), were analyzed. Patients were sub-grouped according to their autoantibody profiles (myositis-specific, myositis-associated, or seronegative). The index date was defined as the time point for the first registered MDI assessment. The longitudinal trajectories of damage with autoantibody status as the main predictor were analyzed using linear mixed models. RESULTS: A total of 757 adult patients were included in this study. Each year of disease duration since diagnosis had an estimated MDI score increase of 0.16 units for the seronegative group (reference). Compared with the seronegative group as reference, patients with dermatomyositis-specific autoantibodies developed less damage per year of follow-up since diagnosis (average 0.08 less score, P = 0.04), whereas patients with anti-PM/Scl autoantibodies developed more damage per year of follow-up since diagnosis (average 0.28 higher score, P = 0.03) independent of sex and age at diagnosis. The seronegative subgroup and the immune-mediated necrotizing myopathy autoantibody subgroup had the strongest correlation between severity of muscle damage and HAQ-DI scores at five years of follow-up, rho=0.84, P < 0.001 and rho=0.72, P < 0.001, respectively. CONCLUSION: Our study is the first to describe patterns and trajectories of change in damage over time in relation to autoantibody defined subgroups in a large international multicenter cohort of patients with IIM. Patients with anti-PM/Scl scored a greater extent of damage, whereas patients with dermatomyositis-specific antibodies had less damage than seronegative patients. Severity in muscle damage had moderate to strong correlation with functional disability among the IMNM and seronegative subgroups with lower correlations for the other subgroups. These findings suggest that autoantibodies may be useful predictors of long-term damage.

• Keywords
• Autoantibodies, Dermatomyositis, Inflammatory myopathies, Myositis, Organ damage,
• MeSH
• Autoantibodies * blood   immunology   MeSH
• Dermatomyositis immunology   blood   MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Longitudinal Studies MeSH
• Myositis * immunology   blood   MeSH
• Disease Progression MeSH
• Registries * MeSH
• Aged MeSH
• Severity of Illness Index MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Multicenter Study MeSH
• Names of Substances
• Autoantibodies * MeSH

OBJECTIVES: To compare clinical characteristics, including the frequency of cutaneous, extramuscular manifestations and malignancy, between adults with anti-synthetase syndrome (ASyS) and DM. METHODS: Using data regarding adults from the MYONET registry, a cohort of DM patients with anti-Mi2/-TIF1γ/-NXP2/-SAE/-MDA5 autoantibodies, and a cohort of ASyS patients with anti-tRNA synthetase autoantibodies (anti-Jo1/-PL7/-PL12/-OJ/-EJ/-Zo/-KS) were identified. Patients with DM sine dermatitis or with discordant dual autoantibody specificities were excluded. Sub-cohorts of patients with ASyS with or without skin involvement were defined based on presence of DM-type rashes (heliotrope rash, Gottron's papules/sign, violaceous rash, shawl sign, V-sign, erythroderma, and/or periorbital rash). RESULTS: In total 1054 patients were included (DM, n = 405; ASyS, n = 649). In the ASyS cohort, 31% (n = 203) had DM-type skin involvement (ASyS-DMskin). A higher frequency of extramuscular manifestations, including Mechanic's hands, Raynaud's phenomenon, arthritis, interstitial lung disease and cardiac involvement differentiated ASyS-DMskin from DM (all P < 0.001), whereas higher frequency of any of four DM-type rashes-heliotrope rash (n = 248, 61% vs n = 90, 44%), violaceous rash (n = 166, 41% vs n = 57, 9%), V-sign (n = 124, 31% vs n = 28, 4%), and shawl sign (n = 133, 33% vs n = 18, 3%)-differentiated DM from ASyS-DMskin (all P < 0.005). Cancer-associated myositis (CAM) was more frequent in DM (n = 67, 17%) compared with ASyS (n = 21, 3%) and ASyS-DMskin (n = 7, 3%) cohorts (both P < 0.001). CONCLUSION: DM-type rashes are frequent in patients with ASyS; however, distinct clinical manifestations differentiate these patients from classical DM. Skin involvement in ASyS does not necessitate increased malignancy surveillance. These findings will inform future ASyS classification criteria and patient management.

• Keywords
• Anti-synthetase syndrome, Cutaneous, Dermatomyositis, Epidemiology, Extramuscular, MYONET, Malignancy, Rashes, Skin,
• MeSH
• Amino Acyl-tRNA Synthetases immunology   MeSH
• Autoantibodies * blood   immunology   MeSH
• Dermatomyositis * immunology   complications   MeSH
• Adult MeSH
• Exanthema etiology   MeSH
• Lung Diseases, Interstitial immunology   etiology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Myositis * immunology   complications   MeSH
• Neoplasms complications   MeSH
• Registries * MeSH
• Aged MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Names of Substances
• Amino Acyl-tRNA Synthetases MeSH
• Autoantibodies * MeSH

BACKGROUND: In patients with idiopathic inflammatory myopathies (IIM), autoantibodies are associated with specific clinical phenotypes suggesting a pathogenic role of adaptive immunity. We explored if autoantibody profiles are associated with specific HLA genetic variants and clinical manifestations in IIM. METHODS: We included 1348 IIM patients and determined the occurrence of 14 myositis-specific or -associated autoantibodies. We used unsupervised cluster analysis to identify autoantibody-defined subgroups and logistic regression to estimate associations with clinical manifestations, HLA-DRB1, HLA-DQA1, HLA-DQB1 alleles, and amino acids imputed from genetic information of HLA class II and I molecules. FINDINGS: We identified eight subgroups with the following dominant autoantibodies: anti-Ro52, -U1RNP, -PM/Scl, -Mi2, -Jo1, -Jo1/Ro52, -TIF1γ or negative for all analysed autoantibodies. Associations with HLA-DRB1∗11, HLA-DRB1∗15, HLA-DQA1∗03, and HLA-DQB1∗03 were present in the anti-U1RNP-dominated subgroup. HLA-DRB1∗03, HLA-DQA1∗05, and HLA-DQB1∗02 alleles were overrepresented in the anti-PM/Scl and anti-Jo1/Ro52-dominated subgroups. HLA-DRB1∗16, HLA-DRB1∗07 alleles were most frequent in anti-Mi2 and HLA-DRB1∗01 and HLA-DRB1∗07 alleles in the anti-TIF1γ subgroup. The HLA-DRB1∗13, HLA-DQA1∗01 and HLA-DQB1∗06 alleles were overrepresented in the negative subgroup. Significant signals from variations in class I molecules were detected in the subgroups dominated by anti-Mi2, anti-Jo1/Ro52, anti-TIF1γ, and the negative subgroup. INTERPRETATION: Distinct HLA class II and I associations were observed for almost all autoantibody-defined subgroups. The associations support autoantibody profiles use for classifying IIM which would likely reflect underlying pathogenic mechanisms better than classifications based on clinical symptoms and/or histopathological features. FUNDING: See a detailed list of funding bodies in the Acknowledgements section at the end of the manuscript.

• Keywords
• Autoantibody, HLA, Idiopathic inflammatory myopathy, Myositis,
• MeSH
• Alleles MeSH
• Autoantibodies * genetics   MeSH
• Phenotype MeSH
• Genetic Predisposition to Disease MeSH
• Haplotypes MeSH
• HLA-DRB1 Chains genetics   MeSH
• Humans MeSH
• Myositis * genetics   immunology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Autoantibodies * MeSH
• HLA-DRB1 Chains MeSH

Major advances have been made in the field of idiopathic inflammatory myopathies (IIM), or myositis, that are likely to facilitate development of new therapeutic strategies that have not yet been applied in this group of diseases. These advances include new classification criteria to better identify the patients with IIM, detection of several new myositis-specific autoantibodies that facilitates subgrouping of patients into more specific clinical phenotypes, development of outcome measures for disease activity, and new response criteria. We have learned from clinical studies that exercise is an important part of treatment and that pharmacologic treatment should be combined with exercise.

• Keywords
• Autoantibodies, Criteria, Exercise, Myositis, Target, Treatment,
• MeSH
• Antirheumatic Agents pharmacology   MeSH
• Autoantibodies analysis   MeSH
• Humans MeSH
• Patient Care Management methods   MeSH
• Myositis * diagnosis   immunology   therapy   MeSH
• Severity of Illness Index MeSH
• Symptom Assessment methods   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Antirheumatic Agents MeSH
• Autoantibodies MeSH

OBJECTIVES: Idiopathic inflammatory myopathies (IIM) are a spectrum of rare autoimmune diseases characterised clinically by muscle weakness and heterogeneous systemic organ involvement. The strongest genetic risk is within the major histocompatibility complex (MHC). Since autoantibody presence defines specific clinical subgroups of IIM, we aimed to correlate serotype and genotype, to identify novel risk variants in the MHC region that co-occur with IIM autoantibodies. METHODS: We collected available autoantibody data in our cohort of 2582 Caucasian patients with IIM. High resolution human leucocyte antigen (HLA) alleles and corresponding amino acid sequences were imputed using SNP2HLA from existing genotyping data and tested for association with 12 autoantibody subgroups. RESULTS: We report associations with eight autoantibodies reaching our study-wide significance level of p<2.9×10-5. Associations with the 8.1 ancestral haplotype were found with anti-Jo-1 (HLA-B*08:01, p=2.28×10-53 and HLA-DRB1*03:01, p=3.25×10-9), anti-PM/Scl (HLA-DQB1*02:01, p=1.47×10-26) and anti-cN1A autoantibodies (HLA-DRB1*03:01, p=1.40×10-11). Associations independent of this haplotype were found with anti-Mi-2 (HLA-DRB1*07:01, p=4.92×10-13) and anti-HMGCR autoantibodies (HLA-DRB1*11, p=5.09×10-6). Amino acid positions may be more strongly associated than classical HLA associations; for example with anti-Jo-1 autoantibodies and position 74 of HLA-DRB1 (p=3.47×10-64) and position 9 of HLA-B (p=7.03×10-11). We report novel genetic associations with HLA-DQB1 anti-TIF1 autoantibodies and identify haplotypes that may differ between adult-onset and juvenile-onset patients with these autoantibodies. CONCLUSIONS: These findings provide new insights regarding the functional consequences of genetic polymorphisms within the MHC. As autoantibodies in IIM correlate with specific clinical features of disease, understanding genetic risk underlying development of autoantibody profiles has implications for future research.

• Keywords
• HLA, autoantibody, genetics, idiopathic inflammatory myopathy, myositis,
• MeSH
• Alleles MeSH
• Autoantibodies genetics   immunology   MeSH
• White People genetics   MeSH
• Adult MeSH
• Genotype MeSH
• Haplotypes MeSH
• HLA-DRB1 Chains genetics   immunology   MeSH
• Major Histocompatibility Complex genetics   MeSH
• Middle Aged MeSH
• Humans MeSH
• Myositis genetics   immunology   MeSH
• Polymorphism, Genetic MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Autoantibodies MeSH
• HLA-DRB1 Chains MeSH

OBJECTIVES: To determine prevalence and co-existence of myositis specific autoantibodies (MSAs) and myositis associated autoantibodies (MAAs) and associated clinical characteristics in a large cohort of idiopathic inflammatory myopathy (IIM) patients. METHODS: Adult patients with confirmed IIM recruited to the EuroMyositis registry (n = 1637) from four centres were investigated for the presence of MSAs/MAAs by radiolabelled-immunoprecipitation, with confirmation of anti-MDA5 and anti-NXP2 by ELISA. Clinical associations for each autoantibody were calculated for 1483 patients with a single or no known autoantibody by global linear regression modelling. RESULTS: MSAs/MAAs were found in 61.5% of patients, with 84.7% of autoantibody positive patients having a sole specificity, and only three cases (0.2%) having more than one MSA. The most frequently detected autoantibody was anti-Jo-1 (18.7%), with a further 21 specificities each found in 0.2-7.9% of patients. Autoantibodies to Mi-2, SAE, TIF1, NXP2, MDA5, PMScl and the non-Jo-1 tRNA-synthetases were strongly associated (p < 0.001) with cutaneous involvement. Anti-TIF1 and anti-Mi-2 positive patients had an increased risk of malignancy (OR 4.67 and 2.50 respectively), and anti-SRP patients had a greater likelihood of cardiac involvement (OR 4.15). Interstitial lung disease was strongly associated with the anti-tRNA synthetases, anti-MDA5, and anti-U1RNP/Sm. Overlap disease was strongly associated with anti-PMScl, anti-Ku, anti-U1RNP/Sm and anti-Ro60. Absence of MSA/MAA was negatively associated with extra-muscular manifestations. CONCLUSIONS: Myositis autoantibodies are present in the majority of patients with IIM and identify distinct clinical subsets. Furthermore, MSAs are nearly always mutually exclusive endorsing their credentials as valuable disease biomarkers.

• Keywords
• Autoantibodies, Autoimmune, Dermatomyositis, Myositis, Polymyositis,
• MeSH
• Autoantibodies immunology   MeSH
• Dermatomyositis epidemiology   immunology   MeSH
• Adult MeSH
• Cohort Studies MeSH
• Comorbidity MeSH
• Middle Aged MeSH
• Humans MeSH
• Myositis diagnosis   epidemiology   immunology   MeSH
• Disease Susceptibility immunology   MeSH
• Odds Ratio MeSH
• Polymyositis epidemiology   immunology   MeSH
• Prevalence MeSH
• Aged MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Europe epidemiology   MeSH
• Names of Substances
• Autoantibodies MeSH

Idiopathic inflammatory myopathies form a heterogeneous group of acquired inflammatory diseases afflicting striated muscles. The disease is frequently accompanied by systemic and organ involvement. Dermatomyositis, polymyositis, cancer associated myositis, immune mediated necrotizing myopathy, myositis in overlap syndromes, juvenile myositis and inclusion body myositis are the most frequently encountered subtypes. The basic manifestation is usually painless muscle weakness brought about by inflammation and by other immune changes at the impacted muscles. Enzymes of muscle origin and myoglobin are found elevated in the circulation. There are changes in electrical properties of muscle fibers detected by EMG. A majority of patients have autoantibodies against nuclear or cytoplasmic antigens in their serum. They are often very specific for these diseases and frequently found in association with particular clinical presentations. For some patients with dermatomyositis the increased incidence of cancer is significantly associated with anti-TIF1γ and anti-NXP2 autoantibodies. Differential diagnostics of inflammatory myopathies is often difficult. Misdiagnosis for a non-inflammatory myopathy is not rare and therefore a very thorough diagnostic approach is necessary. Therapy aims to suppression of autoimmune response using glucocorticoids and immunosuppressive drugs. In large part of patients the response to standard treatment is not sufficient and less common synthetic compounds, biological drugs or intravenous immunoglobulins need to be used. Most patients with inclusion body myositis has limited or no effect of any treatment.Key words: autoantibodies - autoimmunity - inflammation - myopathy - myositis - systemic disease.

• MeSH
• Autoimmune Diseases * diagnosis   drug therapy   immunology   MeSH
• Autoantibodies MeSH
• Dermatomyositis * diagnosis   drug therapy   immunology   MeSH
• Immunoglobulins, Intravenous therapeutic use   MeSH
• Humans MeSH
• Myositis * diagnosis   drug therapy   immunology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Autoantibodies MeSH
• Immunoglobulins, Intravenous MeSH

OBJECTIVES: To analyse the expression regulation of two inducible HSP70 genes - HSPA1A and HSPA1B - located within the major histocompatibility complex (MHC) in patients with various systemic autoimmune diseases and to prove the reliability of MHC-located HSP70 genes as molecular markers reflecting the autoimmune process. METHODS: 94 adult patients with idiopathic inflammatory myopathy (IIM, n=31), systemic lupus erythematosus (SLE, n=31) or systemic sclerosis (SSc, n=32) and 37 healthy individuals were analysed. The mRNA expression level was determined using quantitative real-time PCR method. The expression of intracellular HSP70 was established by flow cytometry, the extracellular HSP70 protein was measured in plasma samples using a commercially available sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: The expression of HSPA1A gene was significantly up-regulated in patients with autoimmune diseases (SLE: p<0.01; SSc: p<0.01; IIM: p<0.0001) compared to healthy controls. The expression of HSPA1B gene was increased only in patients with myositis (p<0.05). Furthermore, the HSPA1B gene expression is associated with the HLA-DRB1*03 risk allele in patients with IIM. In addition, we have found a relation between HSPA1A gene expression regulation and the presence of disease specific autoantibodies in patients with SLE and myositis. The level of intracellular HSP70 was not increased; however, the level of extracellular HSP70 protein was increased in patients suffering from SSc and IIM as compared to controls. CONCLUSIONS: The results suggest an involvement of the MHC-linked HSP70 genes in the pathology of studied autoimmune disorders. Therefore, the HSPA1A and HSPA1B genes might serve as an interesting candidate molecule for development of distinct types of autoimmunities.

• MeSH
• Alleles MeSH
• Autoimmunity genetics   MeSH
• Autoantibodies MeSH
• Biomarkers MeSH
• Adult MeSH
• Genetic Predisposition to Disease MeSH
• Middle Aged MeSH
• Humans MeSH
• Myositis genetics   immunology   MeSH
• HSP70 Heat-Shock Proteins genetics   MeSH
• Gene Expression Regulation MeSH
• Aged MeSH
• Scleroderma, Systemic genetics   immunology   MeSH
• Lupus Erythematosus, Systemic genetics   immunology   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Autoantibodies MeSH
• Biomarkers MeSH
• HSPA1A protein, human MeSH Browser
• HSPA1B protein, human MeSH Browser
• HSP70 Heat-Shock Proteins MeSH

PURPOSE OF REVIEW: To discuss the needs for international collaborations between investigators in different disciplines working with myositis and with patients with myositis. RECENT FINDINGS: Recent advances in detection of several myositis-specific autoantibodies that are associated with distinct clinical phenotypes, will enable studies in new well defined clinically homogenous subgroups of myositis This is likely to lead to development of new information on molecular pathogenesis that might be different in different myositis subgroups. Subgrouping patients according to autoantibody profile may also be important to assess outcome, to identify prognostic biomarkers and in clinical trials. As these are rare disorders international collaboration is essential to enrol large enough cohorts of the subgroups. To facilitate such collaboration we have developed a web-based international myositis register, www.euromyositis.eu, which includes validated outcome measures and patient reported outcome measures. This register is to support research but also to support decision-making in the clinic. We welcome investigators to join the Euromyositis register. SUMMARY: Myositis is a heterogeneous disorder with varying treatment response and outcome. There is a high unmet need for new therapies which can only be achieved by increased knowledge on molecular disease mechanisms. Subgrouping patients according to autoantibody profile may be a new way forward to get a better understanding on disease mechanisms and to develop novel therapies.

• MeSH
• Autoimmunity * MeSH
• Outcome Assessment, Health Care MeSH
• Humans MeSH
• Disease Management * MeSH
• International Cooperation * MeSH
• Myositis immunology   therapy   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH