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Introduction/Background The rare heterogenous autoimmune disease Juvenile Dermatomyositis (JDM) relies on prognostic tools including myositis specific antibodies (MSA) and myositis associated antibodies (MAA) to guide early treatment and reduce the risks of poor outcome. However, there is an emerging concern regarding the inter-assay validity due to the current lack of a standardised protocol for MSA/MAA screening across healthcare centres. Among available MSA/MAA screening assays, most laboratories prefer using immunoblot over immunoprecipitation, due to its practicality and lower cost. Notably, blotting-based assays were reported to have reduced specificity at detecting certain MSA/MAA subgroups. Description/Method A total of 472 JDM patients recruited via UK Juvenile Dermatomyositis Cohort and Biomarker Study (JDCBS) were included in this study. For immunoprecipitation cohort, the sera of 383 JDM-diagnosed patients were determined at the University of Bath using radio-labelled protein immunoprecipitation, and 140kDa bands were confirmed with ELISA for NXP2 or MDA5. For immunoblot cohort (n = 89), MSA/MAA results were obtained from the patients’ records at the centre of care. The immunoprecipitation group and immunoblot group were investigated for the frequency of each autoantibody subgroup within each cohort. The objective was to determine the sensitivity of each assay in detecting myositis relevant antibodies (MSA/MAA) in the context of JDM. Discussion/Results Overall, the majority of patients were female, and self-identified as white. Specifically, in immunoprecipitation cohort, 70.9% of the patients were female, while 77.1% of the patients self-identified as white. In the immunoblot cohort, 72.7% of the patient were female, while 65.9% self-identified as white. Regarding MSA/MAA status in each cohort, 225 out of 383 (58%) immunoprecipitation samples were positive for at least 1 myositis relevant autoantibody (MSA/MAA). In the immunoblot cohort the proportion was 53% (47 out of 89 samples). Despite the similar gender and ethnicity distribution, the frequencies of autoantibody subgroups varied between two cohorts. In descending order, the 3 most common MSAs detected by immunoprecipitation group were anti-TIF1γ (18.1%), anti-NXP2 (15.8%) and anti-MDA5 (5.9%). On the contrary, anti-MDA5 (15.5%) was the most prevalent autoantibody detected by immunoblot, followed by anti-TIF1γ (11.3%) and anti-NXP2 (9.3%), respectively. The prevalence of more than one myositis relevant autoantibodies detected in a patient was rare in both cohorts. Specifically, when excluding anti-Ro52, a MAA that is not detected with immunoprecipitation, 2.2% of the total patients in immunoblot cohort had more than 1 MSA/MAA. This rate is lower in immunoprecipitation cohort, as only 0.5% of the patients in this cohort were determined to be positive for more than one autoantibody subgroup. When accounting for anti-Ro52 in immunoblot cohort, 7 out of 8 anti-Ro52 positive patients were also positive for anti-MDA5, making up 7.9% of immunoblot cohort. Key learning points/Conclusion The variance between autoantibody frequencies detected by each method suggested that immunoprecipitation and immunoblot assays do not perform equally for all MSA and MAA. The lower detection of anti-TIF1γ in immunoblot is consistent with previous reports. Additionally, a potential reduction of sensitivity in anti-NXP2 detection using immunoblot is observed for the first time. Higher rate of anti-MDA5 in immunoblot cohort might reflect the earlier pre-treatment samples compared to the samples tested in immunoprecipitation cohort, as the titre of anti-MDA5 was reported to decrease with treatment. As MSA/MAA status are interpreted by clinicians to classify JDM patients into homogenous subgroups for more focused treatment plans, the reliability of autoantibody screening process is an issue of interest. Further investigations are necessary to characterise the sensitivity and specificity of each method.

Objectives Uncertainty around clinical heterogeneity and outcomes for patients with JDM represents a major burden of disease and a challenge for clinical management. We sought to identify novel classes of patients having similar temporal patterns in disease activity and relate them to baseline clinical features. Methods Data were obtained for n = 519 patients, including baseline demographic and clinical features, baseline and follow-up records of physician’s global assessment of disease (PGA), and skin disease activity (modified DAS). Growth mixture models (GMMs) were fitted to identify classes of patients with similar trajectories of these variables. Baseline predictors of class membership were identified using Lasso regression. Results GMM analysis of PGA identified two classes of patients. Patients in class 1 (89%) tended to improve, while patients in class 2 (11%) had more persistent disease. Lasso regression identified abnormal respiration, lipodystrophy and time since diagnosis as baseline predictors of class 2 membership, with estimated odds ratios, controlling for the other two variables, of 1.91 for presence of abnormal respiration, 1.92 for lipodystrophy and 1.32 for time since diagnosis. GMM analysis of modified DAS identified three classes of patients. Patients in classes 1 (16%) and 2 (12%) had higher levels of modified DAS at diagnosis that improved or remained high, respectively. Patients in class 3 (72%) began with lower DAS levels that improved more quickly. Higher proportions of patients in PGA class 2 were in DAS class 2 (19%, compared with 16 and 10%). Conclusion GMM analysis identified novel JDM phenotypes based on longitudinal PGA and modified DAS.

Background/Aims The RNHRD is a tertiary rheumatology centre offering a fast-track GCA assessment service. A 2018 departmental audit highlighted areas of good practice including timely assessment of cases but demonstrated irregularities in follow up processes. COVID-19 dramatically changed the way we could deliver our GCA service. Additionally, we saw increases in referrals, confirmed diagnoses and complex disease in our local population during the pandemic. This prompted us to undertake a service improvement project. Our main aims were to optimise follow up in line with national guidelines, enhance patient safety and improve the patient experience. Methods We undertook a service review, starting by mapping the patients’ journey. Guidelines were reviewed and stakeholders consulted. We identified several areas for improvement including; consultant-led risk stratification of patients, formalised follow up pathways and closer collaborative working with relevant departments. Additionally, we sought to streamline our processes to accommodate the increased COVID-19 workload. Results A risk stratified follow up pathway was created. Patients are stratified at initial review, by consultants, into low and high-risk pathways. Follow up intervals have been standardised in line with BSR guidance. Follow up patients are reviewed in a dedicated clinic; medical and nursing clinics run supervised by a vasculitis specialist. Patients transfer between different clinics, dependent on clinical stability. Patient information provided has been standardised, with increased emphasis on flare management and steroid side effects. In collaboration with patients this is being incorporated into a “GCA patient passport”, offering a consistent information resource for patients and clinicians. The nurse-led patient advice line is used frequently by GCA patients. All GCA queries are now directed to the on-call registrar, to ensure same day responses. Temporal artery ultrasound is well utilised and completed efficiently; 82% of scans between September 2019 and September 2021 occurred within 48 hours of referral. Via close working with vascular ultrasound, we have been able to create dedicated daily ultrasound capacity. Collaborative working with our Ophthalmology department has increased; communication channels between departments have been agreed, and education sessions have been provided. Processes for new GCA patients were streamlined, for example moving location of reviews. This ensured ongoing timely review of new GCA patients despite increased referral numbers. Conclusion COVID-19 had a significant impact on service delivery but provided a catalyst to develop our service. By engaging with stakeholders across disciplines, and reacting to patient feedback, we have been able to institute effective and meaningful change. This process is iterative and we plan further assessment of outcomes including co-morbidities and complications. Further formal patient surveys and development of a GCA expert patient group are underway and will inform further service development. Disclosure B. Mulhearn: None. J. Ellis: None. S. Smith: None. S.L. Tansley: None. S. Skeoch: None.

Objectives In order to address the reliability of commercial assays to identify myositis-specific and -associated autoantibodies, we aimed to compare the results of two commercial immunoassays with the results obtained by protein immunoprecipitation. Methods Autoantibody status was determined using radio-labelled protein immunoprecipitation for patients referred to our laboratory for myositis autoantibody characterization. For each autoantibody of interest, the sera from 25 different patients were analysed by line blot (Euroline Myositis Antigen Profile 4, EuroImmun, Lübeck, Germany) and dot blot (D-Tek BlueDiver, Diagnostic Technology, Belrose, NSW, Australia). Sera from 134 adult healthy controls were analysed. Results Overall commercial assays performed reasonably well, with high agreement (Cohen’s κ >0.8). Notable exceptions were the detection of rarer anti-synthetases with κ Conclusion The assays analysed do not perform well for all myositis-specific and -associated autoantibodies and overall false positives are relatively common. It is crucial that clinicians are aware of the limitations of the methods used by their local laboratory. Results must be interpreted within the clinical context and immunoprecipitation should still be considered in selected cases, such as apparently autoantibody-negative patients where anti-synthetase syndrome is suspected.

ObjectivesAnti-TIF1γ is an important autoantibody in the diagnosis of cancer-associated dermatomyositis and the most common autoantibody in juvenile onset dermatomyositis. Its reliable detection is important to instigate further investigations into underlying malignancy in adults. We previously showed that commercial assays using line and dot blots do not reliably detect anti-TIF1γ. We aimed to test a new commercial ELISA and compare with previously obtained protein immunoprecipitation.MethodsRadio-labelled immunoprecipitation had previously been used to determine the autoantibody status of patients with immune-mediated inflammatory myopathies and several healthy controls. ELISA was undertaken on healthy control and anti-TIF1γ sera and compared to previous immunoprecipitation data.ResultsA total of 110 serum samples were analysed: 42 myositis patients with anti- TIF1γ and 68 autoantibody negative healthy control sera. Anti-TIF1γ was detected by ELISA in 41 out of 42 of the anti-TIF1γ-positive samples by immunoprecipitation, and in none of the healthy controls, giving a sensitivity of 97.6% and specificity of 100%. The false negative rate was 2%.ConclusionELISA is an affordable and time-efficient method which is accurate in detecting anti-TIF1γ.

Contains fulltext : 238504.pdf (Publisher’s version ) (Open Access) OBJECTIVE: To assess anti-cytosolic 5'-nucleotidase 1A (anti-cN-1A) autoantibodies in children with juvenile dermatomyositis (DM) and healthy controls, using 3 different methods of antibody detection, as well as verification of the results in an independent cohort. METHODS: Anti-cN-1A reactivity was assessed in 34 Dutch juvenile DM patients and 20 healthy juvenile controls using the following methods: a commercially available full-length cN-1A enzyme-linked immunosorbent assay (ELISA), a synthetic peptide ELISA, and immunoblotting with a lysate from cN-1A-expressing HEK 293 cells. Sera from juvenile DM patients with active disease and those with disease in remission were analyzed. An independent British cohort of 110 juvenile DM patients and 43 healthy juvenile controls was assessed using an in-house full-length cN-1A ELISA. RESULTS: Anti-cN-1A reactivity was not present in sera from juvenile DM patients or healthy controls when tested with the commercially available full-length cN-1A ELISA or by immunoblotting, in either active disease or disease in remission. Additionally, in the British juvenile DM cohort, anti-cN-1A reactivity was not detected. Three Dutch juvenile DM patients had weakly positive results for 1 of 3 synthetic cN-1A peptides measured by ELISA. CONCLUSION: Juvenile DM patients and young healthy individuals did not show anti-cN-1A reactivity as assessed by different antibody detection techniques.

Objectives To identify clinical factors associated with cancer risk in the idiopathic inflammatory myopathies (IIMs) and to systematically review the existing evidence related to cancer screening. Methods A systematic literature search was carried out on Medline, Embase and Scopus. Cancer risk within the IIM population (i.e. not compared with the general population) was expressed as risk ratios (RR) for binary variables and weighted mean differences (WMD) for continuous variables. Evidence relating to cancer screening practices in the IIMs were synthesized via narrative review. Results Sixty-nine studies were included in the meta-analysis. DM subtype (RR 2.21), older age (WMD 11.19), male sex (RR 1.53), dysphagia (RR 2.09), cutaneous ulceration (RR 2.73) and anti-transcriptional intermediary factor-1 gamma positivity (RR 4.66) were identified as being associated with significantly increased risk of cancer. PM (RR 0.49) and clinically amyopathic DM (RR 0.44) subtypes, Raynaud’s phenomenon (RR 0.61), interstitial lung disease (RR 0.49), very high serum creatine kinase (WMD −1189.96) or lactate dehydrogenase (WMD −336.52) levels, and anti-Jo1 (RR 0.45) or anti-EJ (RR 0.17) positivity were identified as being associated with significantly reduced risk of cancer. Nine studies relating to IIM-specific cancer screening were included. CT scanning of the thorax, abdomen and pelvis appeared to be effective in identifying underlying asymptomatic cancers. Conclusion Cancer risk factors should be evaluated in patients with IIM for risk stratification. Screening evidence is limited but CT scanning could be useful. Prospective studies and consensus guidelines are needed to establish cancer screening strategies in IIM patients.

Objectives Our centre offers a fast-track assessment service for patients with suspected GCA and this service continued to operate during the coronavirus disease 2019 (COVID-19) pandemic. During and immediately following the peak of the COVID-19 pandemic in the UK we observed an increase in the number of patients diagnosed with GCA as well as an increased number of patients with visual complications. Our aim was to investigate this further. Methods The electronic medical records of all patients referred for GCA fast-track assessment from January 2019 were reviewed. A complete list of patients undergoing temporal artery ultrasound and temporal artery biopsy for investigation of GCA dating back to 2015 was also available. Results In the 12 week period between April and June 2020, 24 patients were diagnosed with GCA. Six (25%) had associated visual impairment. In contrast, during 2019, 28 new diagnoses of GCA were made in total and just 10% of patients suffered visual involvement. The number of patients diagnosed with GCA in April–June 2020 was nearly 5-fold that of the same time period the previous year. GCA diagnoses between April and June 2020 were supported by imaging (temporal artery ultrasound or CT-PET) in 72% of cases. We noted a higher proportion of male patients and a lower median age but no clear difference in the duration of symptoms prior to assessment. Conclusions The reasons behind our observations remain unclear. However, our findings support the viral aetiopathogenesis hypothesis for GCA and demonstrate the importance of maintaining access to urgent rheumatology services during periods of healthcare disruption.

Objectives It has been over 10 years since the first report of autoantibodies directed against phenylalanyl tRNA synthetase (anti-Zo) in a patient with features of the anti-synthetase syndrome. In that time no further cases have been published. Here we aim to characterize more fully the clinical phenotype of anti-Zo–associated myositis by describing the clinical features of nine patients. Methods Anti-Zo was identified by protein-immunoprecipitation in patients referred for extended spectrum myositis autoantibody testing at our laboratory. Results were confirmed by immunodepletion using a reference serum. Medical records were retrospectively reviewed to provide detailed information of the associated clinical phenotype for all identified patients. Where possible, HLA genotype was imputed using Illumina protocols. Results Nine patients with anti-Zo were identified. The median age at disease onset was 51 years, and six patients were female. Seven patients had evidence of inflammatory muscle disease, seven of interstitial lung disease and six of arthritis. The reported pattern of interstitial lung disease varied with usual interstitial pneumonia, non-specific interstitial pneumonia and organizing pneumonia all described. Other features of the anti-synthetase syndrome such as RP and mechanics hands were common. HLA data was available for three patients, all of whom had at least one copy of the HLA 8.1 ancestral haplotype. Conclusion Patients with anti-Zo presenting with features of the anti-synthetase syndrome and interstitial lung disease is a common finding. Like other myositis autoantibodies, there is likely to be a genetic association with the HLA 8.1 ancestral haplotype.

Purpose of ReviewJuvenile dermatomyositis is a heterogeneous disease with variable clinical outcomes. Here, we describe the recognised subtypes of idiopathic inflammatory myositis which occur in children, with particular reference to disease-associated autoantibodies.Recent FindingsLarge cohort studies have demonstrated that myositis autoantibodies are common in juvenile dermatomyositis and can be found in the majority of patients. They identify homogenous clinical subgroups and inform prognosis, particularly the risks of developing interstitial lung disease. Descriptions of immune-mediated necrotising myositis in juvenile patients have highlighted a rare but important clinical subset typically associated with severe muscle disease and treatment resistance.SummaryIt is increasingly apparent that autoantibodies can provide detailed information on prognosis and the likely disease associations in those with juvenile dermatomyositis. Further work is needed to establish how this knowledge should influence our approach to treatment.

Background:The myositis specific autoantibody anti-TIF1γ targets TRIM33, a TRIM family proetin with a PHDBromo domain at the C terminal end. Anti-TIF1γ is strongly associated with malignancy in adult patients with idiopathic inflammatory myopathies (IIM). Intriguingly, anti-TIF1γ is also the most common autoantibody in juvenile-onset IIM but younger patients with anti-TIF1γ do not have an increased risk of cancer (1-3). Genetic studies have consistently shown human leukocyte antigen (HLA) to be the strongest risk factor for IIM. Adult and juvenile-onset patients with anti-TIF1γ have recently been shown to have different associations at the HLA-DQB1 locus (4). This could be due to differences in the key TIF1γ epitopes and may relate to differences in aetiology, such as malignancy in adults versus other environmental factors in juvenile onset disease.Objectives:To identify key epitopes targeted by anti-TIF1γ antibody in patients with IIM and establish if different TIF1γ epitopes are targeted in patients with and without malignancy.Methods:Patient plasma/serum samples were obtained from UK Juvenile Dermatomyositis Cohort and Biomarker and UKMyoNet studies. Autoantibody status had previously been determined by immunoprecipitation. Cancer data was collated from the UK Health and Social Care Information Centre and cancer associated IIM (CAM) defined as that occurring within 3 years of IIM diagnosis.An in house ELISA was developed using a purified TIF1γ fragment comprising residues 882-1090, produced in E.coli, corresponding to the PHDBromo protein domain. An ELISA cut-off of 5SD above the mean of 38 healthy control samples was used.Results:38 healthy controls, and 117 anti-TIF1γ IIM patient sera (60 juvenile onset) were analysed for reactivity to the TIF1γ PHDbromo domain.No healthy controls were positive. Anti-TIF1γPHDbromo was more common in JDM: 18 (30%) juvenile patients and 6 (10.5%) adult patients were positive, p=0.01.Additional data was available for 39 adult patients (82% female, median age 52 (IQR 38-64)). Anti-TIF1γPHDbromo was only found in CAM patients plus one young adult non-CAM patient aged 27 years at disease onset, p =0.07 (p=0.02 for patients >30 years at disease onset), see Table 1. No juvenile patients had a history of malignancy.Table 1.Anti-TIF1γPHDbromo in 39 adult patients with cancer data availableanti-TIF1γPHDbromo positiveanti-TIF1γPHDbromo negativeCancer associated myositis n(%)5a (83)12(36)Myositis not associated with cancer n(%)1b(17)21(64)Total633a. Median age 64 yearsb. Age 27 yearsConclusion:The TIF1γ PHDBromo domain is an important epitope and autoantibody reactivity is more common in patients with juvenile-onset disease and adults with CAM. The distinction between adult and juvenile-onset IIM is arbitrary and it is relevant that the only adult with anti-TIF1γPHDbromo not to have malignancy was just 27 years old. Our numbers are small and further work is needed to establish if anti-TIF1γPHDbromo, and indeed other TIF1γ epitopes, could help identify patients at highest risk of malignancy, and how this relates to our understanding of IIM aetiopathogenesis. Our findings may add weight to the theory that the development of IIM in younger patients occurs after immune-mediated resolution of a pre-cancer event.References:[1]Oldroyd A, Sergeant JC, New P et al. The temporal relationship between cancer and adult onset anti-transcriptional intermediary factor 1 antibody-positive dermatomyositis. Rheumatology. 2019;58(4):650-655[2]Tansley SL, Simou S, Shaddick G et al. Autoantibodies in juvenile-onset myositis: Their diagnostic value and associated clinical phenotype in a large UK cohort. J Autoimmun. 2017;84:55-64[3]Fujimoto M, Hamaguchi Y, Kaji K et al. Myositis-specific anti-155/140 autoantibodies target transcription intermediary factor 1 family proteins. Arthritis Rheum. 2012;64(2):513-22.[4]Rothwell S, Chinoy H, Lamb JA et al. Focused HLA analysis in Caucasians with myositis identifies significant associations with autoantibody subgroups. Ann Rheum Dis. 2019;78(7):996-1002.Disclosure of Interests:None declared

Aims To evaluate the relationship between expression of myxovirus-resistance protein A (MxA) protein on muscle biopsies by immunohistochemistry and disease activity in juvenile dermatomyositis (JDM) patients. Also, another aim was to investigate whether the expression of MxA is related with myositis-specific autoantibodies (MSA) status in JDM patients. Methods 103 patients (median aged 6.3, interquartile range 0.5-15.9) enrolled in the Juvenile Dermatomyositis Cohort and Biomarker Study (JDCBS). Muscle biopsies were stained with MxA and scored. Clinical data at initial presentation were collected and autoantibodies were analysed. Multiple linear regression analysis was performed to estimate the association between MxA expression on muscle fibres and muscle disease activity, and MSA status. Results Expression of MxA protein on JDM samples was identified in 61.2%. There was a significant association between MxA scores and Childhood Myositis Assessment Scale (CMAS) (P = 0.002), and Manual Muscle Testing of Eight Muscles (MMT8) (P = 0.026). CMAS and MMT8 scores were significantly lower in the group of patients with strong MxA expression. MxA scores differed according to MSA subgroups (P = 0.002). Patients with positive nuclear matrix protein 2 autoantibodies had strong MxA expression, whereas anti-melanoma differentiation-associated gene 5 positive patients had no or weak MxA expression. Conclusions This study reveals the significant association between level of MxA expression on muscle fibres and clinical measures of muscular disease activity in JDM patients and MSA status. This confirms type I interferonopathies in muscle fibres of JDM patients which could help with improving treatment outcome in JDM patients and underscoring the distinct pathophysiological pathways in different MSA status.

ObjectivesIdiopathic 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.MethodsWe 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.ResultsWe report associations with eight autoantibodies reaching our study-wide significance level of p–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.ConclusionsThese 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.

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, Highlights • Myositis specific autoantibodies very rarely coexist in the one individual allowing endotypes to be more precisely defined. • The association of anti-TIF1 and cancer-associated myositis is confirmed with a cut-off age of over 58 years. • In a large combined European myositis cohort associations of anti-SRP with carditis and anti-Mi-2 with cancer have emerged. • Myositis associated autoantibodies are strongly associated with having myositis in association with another connective tissue disease.

Autoimmune connective tissue diseases are heterogeneous rheumatic diseases with the potential to affect multiple body systems. Autoantibodies are a characteristic feature of these diseases and are typically highly disease specific. In addition to aiding diagnosis, many autoantibodies have established associations with clinically important disease complications including internal organ involvement. In this chapter, we review the autoantibodies relevant to autoimmune connective tissue diseases, excluding systemic lupus erythematosus, with particular reference to the associated clinical features and how identification of such an autoantibody may inform prognosis and clinical management. We also discuss the practicalities of testing for autoantibodies along with potential difficulties and pitfalls.

Myositis-specific or myositis-associated antibodies can be found in most patients with myositis and are associated with distinct disease phenotypes. These antibodies also provide valuable insights into the pathogenesis of myositis and can help guide treatment. The discovery of novel autoantigen systems related to idiopathic inflammatory myopathies (collectively referred to as myositis) in adults and children has had major implications for the diagnosis and management of this group of diseases across a wide range of medical specialties. Traditionally, autoantibodies found in patients with myositis are described as being myositis-specific autoantibodies (MSAs) or myositis-associated autoantibodies (MAAs), depending on their prevalence in other, related conditions. However, certain MSAs are more closely associated with extramuscular manifestations, such as skin and lung disease, than with myositis itself. It is very rare for more than one MSA to coexist in the same individual, underpinning the potential to use MSAs to precisely define genetic and disease endotypes. Each MSA is associated with a distinctive pattern of disease or phenotype, which has implications for diagnosis and a more personalized approach to therapy. Knowledge of the function and localization of the autoantigenic targets for MSAs has provided key insights into the potential immunopathogenic mechanisms of myositis. In particular, evidence suggests that the alteration of expression of a myositis-related autoantigen by certain environmental influences or oncogenesis could be a pivotal event linking autoantibody generation to the development of disease.

This chapter describes the laboratory tests useful in diagnosing and monitoring patients with myositis. It describes creatinine kinase, it’s different isoforms and explains why this muscle enzyme is helpful in the diagnosis and monitoring of patients with inflammatory muscle disease. It also describes other skeletal muscle enzymes that are often elevated in both adult and juvenile onset disease and examines the specificity of troponins for cardiac muscle involvement. The prevalence and clinical utility of myositis specific and associated autoantibodies is explored, and we report the clinical features associated with different autoantibody subgroups, demonstrating how such autoantibodies can divide patients into clinically homogenous subgroups. Finally, evidence for the potential use of other novel biomarkers including cytokines is also explored.

Dermatomyositis and polymyositis are rare chronic inflammatory disorders with significant associated morbidity and mortality despite treatment. High-dose corticosteroids in addition to other interventions such as immunosuppressants, immunomodulators, and more recently, biologics are commonly used in clinical practice; however, there are no clear guidelines directing their use. Our objective was to systematically review the evidence for immunotherapy in the treatment of dermatomyositis and polymyositis. Relevant studies were identified through Embase and PubMed database searches. Trials were selected using pre-determined selection criteria and then assessed for quality. Randomized controlled trials and experimental studies without true randomization and including adult patients with definite or probable dermatomyositis or polymyositis were evaluated. Any type of immunotherapy was considered. Clinical improvement, judged by assessment of muscle strength after 6 months, was the primary outcome. Secondary outcomes included IMACS definition of improvement, improvements in patient and physician global scores, physical function, and muscle enzymes. Twelve studies met eligibility criteria. Differences in trial design, quality, and variable reporting of baseline characteristics and outcomes made direct comparison impossible. Although no treatment can be recommended on the basis of this review, improved outcomes were demonstrated with a number of agents including methotrexate, azathioprine, ciclosporin, rituximab, and intravenous immunoglobulin. Plasmapheresis and leukapheresis were of no apparent benefit. More high-quality randomized controlled trials are needed to establish the role of immunosuppressive agents in the treatment of these conditions and the clinical context in which they are most likely to be beneficial.

Objective.We aimed to establish the prevalence and clinical associations of anti-HMG-CoA-reductase (anti-HMGCR) in a large UK cohort with juvenile myositis.Methods.There were 381 patients investigated for anti-HMGCR using ELISA.Results.Anti-HMGCR autoantibodies were detected in 4 patients (1%). These children had no or minimal rash and significant muscle disease. Muscle biopsies were considered distinctive, with widespread variation in fiber size, necrotic fibers, and chronic inflammatory cell infiltrates; all had prolonged elevation of creatine kinase and all ultimately received biologic therapies.Conclusion.Anti-HMGCR in UK children with myositis are associated with severe disease that is poorly responsive to standard treatment.

The purpose of this study is to review recent advances in the diagnostic utility of autoantibodies in dermatomyositis.Alternative nonspecialist testing methods have been developed for anti-transcription intermediary factor 1 gamma, anti-MDA5 and anti-nuclear matrix protein 2, which are potentially exploitable by any hospital laboratory. Although these have yet to be validated for diagnostic use, it is likely that testing for myositis-specific antibodies will soon become readily available.The identification of myositis-specific autoantibodies provides both diagnostic and prognostic information and offers a unique opportunity to adopt a stratified approach to treatment. Their identification, in many cases, should prevent the need for invasive diagnostic tests such as muscle biopsy.

The idiopathic inflammatory myopathies: polymyositis (PM) and dermatomyositis (DM) have been historically defined by broad clinical and pathological criteria. These conditions affect both adults and children with clinical features including muscle weakness, skin disease and internal organ involvement. Over the last few years, it has become increasingly apparent that using a clinico-serological approach, both DM and PM can be defined into more homogeneous subsets. A large number of antibodies are directed against cytoplasmic or nuclear components involved in key regulatory intra-cellular processes including protein synthesis, translocation and gene transcription within this disease spectrum. In addition, these autoantibodies are found in patients with clinical features other than myositis, in particular 'idiopathic' interstitial pneumonia emphasizing that these patients may in fact be a formes-frustes of autoimmune connective tissue disease. Other important findings are the identification of specific autoantibodies in both cancer-associated dermatomyositis, clinically amyopathic dermatomyositis and juvenile dermatomyositis, which previously were classically described as antibody-negative clinical subsets. Finally, work has highlighted how target autoantigens identified in the myositis-connective tissue disease overlap share common cellular mechanisms, which provides us with further insights into disease pathogenesis.

Juvenile-onset myositis is a highly heterogeneous disease. Myositis-specific and associated autoantibodies provide a potential means of subdividing patients into clinically homogenous subgroups. Given the increasing availability of autoantibody testing, this review explores the phenotypes associated with different autoantibodies in juvenile-onset myositis and the potential clinical utility of autoantibody testing.Autoantibodies can be identified in 60-70% of children with myositis and the recent discovery of novel myositis-associated autoantibodies in adult patients suggests this may increase in the near future. Detailed phenotype descriptions are now known for several autoantibodies commonly identified in juvenile-onset disease. Whilst there is insufficient evidence to recommend a differential treatment approach based on autoantibody status, it is becoming increasingly clear that some autoantibody subgroups are often treatment resistant and may benefit from a more aggressive approach.The validation of nonspecialised methods for myositis-specific autoantibody detection should lead to more widely available testing. In juvenile-onset disease, this will provide detailed prognostic information and in the future may also influence approach.

In this review we explore the different characteristics of the serological phenotypes identified in juvenile-onset myositis and consider how the serological sub-classification of patients with juvenile myositis can be advantageous both in terms of reaching what can be a difficult diagnosis and informing on prognosis. Recent studies have described the autoantibody associated disease phenotypes and outcome for those with juvenile-onset disease and include analyses of large juvenile-onset myositis cohorts. Here we describe the autoantibody associated disease features for patients within juvenile-onset myositis in detail and discuss the expanding opportunities and strategies for myositis specific autoantibody testing in clinical practice.

Aim: The aim of this study is to determine whether the analysis of CD38 expression by chronic lymphocytic leukaemia (CLL) cells provides useful additional prognostic information. Methods: Clinical, laboratory, overall survival (OS) and treatment-free survival (TFS) data were collected on 130 CLL patients who had CD38 expression analysed at Canterbury Health Laboratories, New Zealand (NZ) during 1998–2008. Results: The detection of any level of CD38 expression by CLL cells was associated with a significantly shorter OS and TFS. When analysis was restricted to Binet stage A patients, CD38 expression identified a subset of patients (21%) who, in common with Binet stage B/C patients, had a significantly shorter OS and TFS (P < 0.0015), and a TFS at 4 years of

To explore the different characteristics of the serological phenotypes identified in juvenile and adult myositis, consider how differences between the two groups might be explained and discuss how this enhances our understanding of disease pathogenesis.Current research has focussed on two main areas: first, defining the autoantibody associated disease phenotype in greater detail, particularly with regard to cutaneous disease and within specified populations such as juvenile-onset disease and different ethnic groups, and second, we have gained new insights into disease pathogenesis through studies analysing genetic associations and autoantigen expression.Although there are many clinically important differences between adult and juvenile-onset myositis, recent work has highlighted many of the similarities at least within autoantibody-defined subgroups. Viewing age at disease onset as a continuum with its own influence on disease phenotype strengthens the ability of autoantibodies to define homogenous disease groups, and may be important in understanding the relationship between autoantibodies and disease pathogenesis.

The idiopathic inflammatory myopathies are a heterogeneous group of disorders affecting both adults and children. Clinical features can include muscle weakness, skin disease and internal organ involvement. A large number of autoantibodies, directed against cytoplasmic or nuclear components, can now be identified in these patients and specific clinic-serological syndromes have been described. Laboratory testing to identify many of these autoantibodies is becoming easier, and here we discuss the clinical utility of autoantibodies in myositis both in terms of facilitating diagnosis, predicting disease course and informing management decisions.

Juvenile Dermatomyositis (JDM) is a rare serious disease (affecting 2-3 million children/year) presenting with rash and proximal muscle weakness. Serious complications can include calcinosis, GI ulceration, interstitial lung disease (ILD) and even death. It is becoming clear that JDM is a heterogeneous condition. Dividing JDM into sub-phenotypes would allow better prediction of disease severity and more targeted treatments. We have identified novel auto-antibodies in subtypes of JDM that may correlate with specific phenotypes.

Objective. Calcinosis is a major cause of morbidity in JDM and has previously been linked to anti-NXP2 autoantibodies, younger age at disease onset and more persistent disease activity. This study aimed to investigate the clinical associations of anti-NXP2 autoantibodies in patients with JDM stratified by age at disease onset. Methods. A total of 285 patients with samples and clinical data were recruited via the UK Juvenile Dermatomyositis Cohort and Biomarker Study. The presence of anti-NXP2 was determined by both immunoprecipitation and ELISA. Logistic regression analysis was performed to assess the age-dependent relationship between anti-NXP2 and the development of calcinosis and disease activity measures. Results. We identified anti-NXP2 autoantibodies in 56 patients (20%). While in all patients younger age at disease onset was associated with an increased risk of calcinosis and this relationship was nearly linear, anti-NXP2 autoantibodies substantially increased the risk of calcinosis across all ages (P = 0.025) and were detectable prior to calcinosis development. Children with anti-NXP2 autoantibodies had a greater degree of weakness (median lowest ever Childhood Myositis Assessment Score 29.6 vs 42) and were less likely to be in remission at 2 years post-diagnosis. No difference in disease activity was seen 4 years post-diagnosis. Conclusion. Children diagnosed at a young age have a high risk of calcinosis regardless of autoantibody status. However, the presence of anti-NXP2 autoantibodies substantially increases the risk of calcinosis across all ages and is associated with disease severity.

Adult and juvenile dermatomyositis share the hallmark features of pathognomic skin rash and muscle inflammation, but are heterogeneous disorders with a range of additional disease features and complications. The frequency of important clinical features such as calcinosis, interstitial lung disease and malignancy varies markedly between adult and juvenile disease. These differences may reflect different disease triggers between children and adults, but whilst various viral and other environmental triggers have been implicated, results are so far conflicting. Myositis-specific autoantibodies can be detected in both adults and children with idiopathic inflammatory myopathies. They are associated with specific disease phenotypes and complications, and divide patients into clinically homogenous subgroups. Interestingly, whilst the same autoantibodies are found in both adults and children, the disease features remain different within autoantibody subgroups, particularly with regard to life-threatening disease associations, such as malignancy and rapidly progressive interstitial lung disease. Our understanding of the mechanisms that underlie these differences is limited by a lack of studies directly comparing adults and children. Dermatomyositis is an autoimmune disease, which is believed to develop as a result of an environmental trigger in a genetically predisposed individual. Age-specific host immune responses and muscle physiology may be additional complicating factors that have significant impact on disease presentation. Further study into this area may produce new insights into disease pathogenesis.

Myositis specific autoantibodies (MSA), exclusively found in patients with Idiopathic Inflammatory Myopathies can be detected in approximately 60% of children with JDM. Anti-MDA5 antibodies, a subgroup of MSA, appear to be associated with clinically amyopathic myositis, rapidly progressive interstitial lung disease (RP-ILD) and a poor prognosis in adult East Asian dermatomyositis patients. Small studies in Japanese children with JDM have suggested similar disease phenotype. This contrasts dramatically with findings in predominantly Caucasian US adult populations where anti-MDA5 has been associated with a distinct cutaneous phenotype and no association with RP-ILD has been found.