Novel autoantibodies and clinical phenotypes in adult and juvenile myositis

Idiopathic inflammatory myopathies: current insights and future frontiers

Idiopathic inflammatory myopathies are a group of autoimmune diseases with a broad spectrum of clinical presentations, primarily characterised by immune-mediated muscle injury. Until recently, there was little insight into the pathogenesis of idiopathic inflammatory myopathies, which challenged the recognition of the breadth of heterogeneity of this group of diseases as well as the development of new therapeutics. However, the landscape of idiopathic inflammatory myopathies is evolving. In the past decade, advances in diagnostic tools have facilitated an enhanced understanding of the underlying disease mechanisms in idiopathic inflammatory myopathies, enabling the expansion of therapeutic trials. The fields of transcriptomics, prot§eomics, and machine learning offer the potential to gain greater insights into the underlying pathophysiology of idiopathic inflammatory myopathies. Harnessing insights gained from these sophisticated tools could contribute to the identification of differences at a molecular level among patients, accelerating the development of targeted, tailored therapies. Bolstered by the validation and standardisation of robust outcome measures, many promising therapies are in clinical trial development. Although challenges remain, there is great optimism in the field due to the progress in innovative diagnostics, outcome measures, and therapeutic approaches. In this Review, we discuss the expanding landscape of idiopathic inflammatory myopathies as the frontier of precision medicine becomes imminent.

A Rare Case of Anti-TIF-1γ Antibody Positive Dermatomyositis in Adulthood

Dermatomyositis (DM) presents with inflammatory myopathy and distinct skin manifestations, often linked to specific autoantibodies. Anti-transcriptional intermediary factor-1 gamma (TIF-1γ) antibodies (Abs) are typically linked to DM in older patients and malignancy in 15% to 40% of cases. We highlight a case of a 24-year-old female who presented with weakness of proximal muscles, periorbital edema, heliotrope rash, erosions on oral mucosa, and painful scaly rash on the lower extremities. Transcriptional intermediary factor-1 gamma Abs were positive, confirming inflammatory myopathy. Treatment with steroid pulse therapy and immunoglobulin led to improvement. Evaluation for malignancy yielded unremarkable results. This case underscores the importance of recognizing and managing DM with TIF-1γ Ab positive, even in atypical demographics, and highlights the need for comprehensive malignancy evaluation.

Research progress on the dermatomyositis specific autoantibodies and malignancy associated dermatomyositis

Dermatomyositis (DM) is an autoimmune disease often complicated with malignant tumors. More than 50% of DM patients have myositis specific autoantibodies in their bodies. DM specific autoantibodies [including anti-migration inhibitory factor (Mi)-2 antibody, anti-nuclear matrix protein (NXP)-2 antibody, anti-transcription intermediary factor (TIF) 1-γ antibody, and anti-small ubiquitin like modifier activating enzyme (SAE) antibody] play important roles in the pathogenesis of malignancy associated DM. Revealing the role of DM specific autoantibodies in the development of malignant tumors in DM patients can provide important evidence for accurately assessing the risk of developing malignant tumors in DM patients, and also provide new ideas for clinical diagnosis of DM and precise treatment.

Myopathy in systemic sclerosis

PURPOSE OF REVIEW

Systemic sclerosis associated myopathy (SSc-AM) is a complex, heterogenous disease that is associated with poor outcomes. SSc-AM lacks a clear definition, and continues to be poorly recognized. The purpose of this review is to provide a contemporary overview of the clinical, serological and pathophysiologic findings in SSc-AM to guide optimal recognition and management of this challenging disease manifestation.

RECENT FINDINGS

There have been several advances in diagnostic techniques to facilitate characterization of SSc-AM, including muscle MRI, in which findings were correlated to distinct histopathologic categories of muscle involvement in SSc, histopathologic findings of prominent fibrosis or inflammation on biopsy, and the identification of novel autoantibodies associated with SSc-AM, which may be associated with distinct clinical phenotypes. In one of the largest studies to date, 17% of a well phenotyped SSc cohort were found to have myopathy, which was an independent risk of death, even after adjusting for potential confounders, further highlighting the importance of timely recognistion and management of SSc-AM.

SUMMARY

There is increasing recognition of the importance of SSc-AM. Novel diagnostic tools provide the opportunity for more detailed insights into pathophysiologic mechanisms, which may facilitate the development of a rigorous consensus definition of SSc-AM.

Clinical pearls and promising therapies in myositis

INTRODUCTION

Idiopathic inflammatory myopathies (IIMs) represent a diverse group of systemic autoimmune disorders with variable clinical manifestations and disease course. Currently, the challenges of IIMs are multifold, including difficulties in timely diagnosis owing to clinical heterogeneity, limited insights into disease pathogenesis, as well as a restricted number of available therapies. However, advances utilizing myositis-specific autoantibodies have facilitated the definition of subgroups as well as the prediction of clinical phenotypes, disease course, and response to treatment.

AREAS COVERED

Herein we provide an overview of the clinical presentations of dermatomyositis, anti-synthetase syndrome, immune-mediated necrotizing myopathy, and inclusion body myositis. We then provide an updated review of available and promising therapies for each of these disease groups. We synthesize current treatment recommendations in the context of case-based construct to facilitate application to patient care. Finally, we provide high-yield, clinical pearls relevant to each of the subgroups that can be incorporated into clinical reasoning.

EXPERT OPINION

There are many exciting developments on the horizon for IIM. As insights into pathogenesis evolve, the therapeutic armamentarium is expanding with many novel therapies in development, holding promise for more targeted treatment approaches.

Possible future avenues for myositis therapeutics: DM, IMNM and IBM

Idiopathic inflammatory myopathies (IIMs) represent a heterogeneous group of systemic autoimmune diseases characterized by immune-mediated muscle injury. As insights into pathogenesis of IIM evolve, novel therapeutic strategies have become available to optimize outcomes. Herein, we summarize novel and emerging strategies in the management of dermatomyositis (DM), immunemediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM).

Interstitial Lung Disease Associated with Connective Tissue Diseases

Pulmonary manifestations of connective tissue diseases (CTD) carry high morbidity and potential mortality, and the most serious pulmonary type is interstitial lung disease (ILD). Identifying and promptly intervening CTD-ILD with immune suppressor therapy will change the natural course of the disease resulting in survival improvement. Compared to idiopathic pulmonary fibrosis, the most common presentation of idiopathic interstitial pneumonia (IIP), CTD-ILD carries a better prognosis due to the response to immune suppressor therapy. Nonspecific interstitial pneumonia (NSIP) is the most common type of CTD-ILD that is different from the fibrotic classical presentation of IPF, known as usual interstitial pneumonia (UIP). An exception is rheumatoid arthritis that presents more frequently with UIP type. Occasionally, IPF may not have typical radiographic features of UIP, and a full assessment to differentiate IPF from CTD-ILD is necessary, including the intervention of a multidisciplinary team and the histopathology. Interstitial pneumonia with autoimmune features (IPAF) shows promising advantages to identify patients with ILD who have some features of a CTD without a defined autoimmune disease and who may benefit from immune suppressors. A composition of clinical, serological, and morphologic features in patients presenting with ILD will fulfill criteria for IPAF. In summary, the early recognition and treatment of CTD-ILD, differentiation from IPF-UIP, and identification of patients with IPAF fulfill the assessment by the clinician for an optimal care.

COVID-19 or clinical amyopathic dermatomyositis associated rapidly progressive interstitial lung disease? A case report

Background

Coronavirus disease 2019 (COVID-19) has reach pandemic proportions globally. For patients with symptoms of fever and cough accompanied by rapid lung damage progression, COVID-19 needs to be distinguished from interstitial lung disease (ILD) attributed to connective tissue disease (CTD), especially dermatomyositis (DM)/clinical amyopathic dermatomyositis (CADM) associated rapidly progressive interstitial lung disease (RP-ILD).

Case presentation

We report a case of a woman observed with fever, cough, and rapid lung damage during the epidemic. The patient had a suspicious epidemiological history, and her chest CT scans showed lung damage similar to that caused by COVID-19, but anti-Ro52 antibody was strongly positive. She was diagnosed with CADM associated RP-ILD and died 1 month later.

Conclusions

During the COVID-19 epidemic, it is critical to carefully assess patients with CTD related ILD, especially RP-ILD associated with CADM. Repeated nucleic acid tests for COVID-19 are necessary to achieve accurate case diagnosis. High-resolution CT (HRCT) of the chest is presently deemed an inefficient technique to distinguishing between COVID-19 and CADM associated RP-ILD. The characteristic rashes of dermatomyositis require careful observation and can often provide diagnostic clues. For patients with CADM, a high titers of anti-Ro52 antibody may be related to the pathogenesis of RP-ILD, suggesting a poor prognosis.

Anti-TIF1-γ autoantibodies: warning lights of a tumour autoantigen

Anti-transcription intermediary factor 1 (TIF1)-γ autoantibodies are robustly linked with cancer-associated DM in adults. This review aims to give an overview of the physiological context of TIF1-γ and to determine whether there is a pathophysiological link between anti-TIF1-γ autoantibodies and the occurrence of cancer. Detection of anti-TIF1-γ autoantibodies has a high sensitivity and specificity for cancer-associated DM in adults and is therefore useful for both diagnosis and cancer risk stratification. The function of the autoantigen, TIF1-γ, may provide insight into the mechanism behind this association. TIF1-γ is a ubiquitously present protein involved in various biological pathways, including TGF-β signalling. In cancer, it can act either as a tumour suppressor or promoter, depending on the cellular context and cancer stage. Evolving data provide pathophysiological insights, linking anti-TIF1-γ autoantibodies to both the anti-tumour response and to muscle and skin damage. TIF1-γ expression is increased in muscle and skin tissue of patients with DM. Mutations or loss-of-heterozygosity in TIF1-γ alleles in malignant tissue may result in the expression of tumour-specific neo-antigens stimulating autoantibody production. The newly formed autoantibodies are hypothesized to cross-react with antigens in muscle and skin, driving the development of DM. Based on the current evidence, anti-TIF1-γ autoantibodies should be considered warning lights of a potential tumour autoantigen and should alert the physician to the possibility of an underlying cancer.

The cancer immunotherapy environment may confound the utility of anti-TIF-1γ in differentiating between paraneoplastic and treatment-related dermatomyositis. Report of a case and review of the literature

With the advent of immunotherapy and with the expanding spectrum of malignancies treated with immunomodulatory agents, a new kind of adverse events has come under the spotlight. Clinicians have to be aware of immune-related adverse events and their clinical manifestations. Immunotherapy has been strongly associated with endocrinopathies, gastrointestinal, pulmonary, cutaneous, and renal toxicities but the incidence of rheumatologic adverse events is lower compared to the aforementioned systems. Dermatomyositis is an autoimmune myopathy which has been correlated to underlying evident or occult malignancies. Apart from its characteristic symptoms and signs, the presence of specific antibodies such as anti-transcriptional intermediary factor 1γ (anti-TIF 1γ) usually supports the diagnosis of paraneoplastic nature of the disease. However, a solid distinction between paraneoplastic syndrome and immune-related adverse event is still missing and remains to be elucidated. We here present a case of dermatomyositis in a male patient who underwent four cycles of combined ipilimumab and nivolumab immunotherapy. This is, to our knowledge, the first case of dermatomyositis following combined immune checkpoint inhibition therapy.

Juvenile dermatomyositis: advances in clinical presentation, myositis-specific antibodies and treatment

BACKGROUND

Juvenile dermatomyositis (JDM) is a chronic autoimmune disease characteristic by inflammation of small vessels within the skin, muscle and vital organs. But the clinical features and treatment of JDM have not been fully clarified.

DATA SOURCES

Databases underwent through PubMed for articles about the clinical features, myositis-specific antibodies of JDM and its treatment, and we selected publications written in English which were relevant to the topic of this review.

RESULTS

Clinical features and myositis-specific antibodies may predict the severity and prognosis of disease. Although the mortality rate has been lower with traditional treatments, such as corticosteroid, intravenous immunoglobulin, and disease-modifying anti-rheumatic drugs such as methotrexate, their usages are variable. Novel biological therapies seem to be effective for refractory JDM patients, but more clinical trials are necessary.

CONCLUSIONS

JDM is a sever disease of childhood. We need to better understand recent advances of JDM in the context of clinical features including skin manifestations, muscle weakness and organ damage, myositis-specific antibodies and their associated outcomes and the treatment of disease.

Risk of major autoimmune diseases in female breast cancer patients: A nationwide, population-based cohort study

BACKGROUND

Breast cancer is one of the most common malignancies among women. However, there remains no consensus in current literature on the incidence of autoimmune diseases among breast cancer patients. The purpose of this study was to evaluate the risks of major autoimmune diseases (MAD) including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Sjögren's syndrome (SS) and dermatomyositis (DMtis)/polymyositis (PM) in female breast cancer patients.

METHODS

Using the Taiwanese National Health Insurance Research Database (NHIRD) records from 2003 to 2013, we identified newly-diagnosed female breast cancer patients and randomly selected females without breast cancer in the period 2007 to 2013 into a control group. We matched the two cohorts using a 1:4 ratio based on age, and the year of index date for comparison of the risk of major autoimmune diseases. We estimated and compared the relative risks of autoimmune diseases in female breast cancer patients and females without breast cancer.

RESULTS

A total of 54,311 females with breast cancer and 217,244 matched females without breast cancer were included in this study. For SLE, the incidence rates were 2.3 (breast cancer group) vs. 10.0 (control group) per 100,000 women years; for RA rates were 19.3 (breast cancer group) vs. 42.7 (control group) per 100,000 women years; and for SS rates were 20.5 (breast cancer group) vs. 38.2 (control group) per 100,000 women years. After adjusting for potential confounders, the hazard ratios (95% confidence intervals) for female breast cancer patients vs. control group were 0.04 (0.01-0.24) for SLE; 0.03 (0.02-0.04) for RA; and 0.21 (0.09-0.48) for SS.

CONCLUSION

Female breast cancer patients had lower risks of SLE, RA and SS when compared to female individuals without breast cancer. However, there was no significant difference in the risk of developing DMtis/PM between both groups.

Disease Specific Autoantibodies in Idiopathic Inflammatory Myopathies

Idiopathic inflammatory myopathies represent still a diagnostic and therapeutic challenge in different disciplines including neurology, rheumatology, and dermatology. In recent years, the spectrum of idiopathic inflammatory myopathies has been significantly extended and the different manifestations were described in more detail leading to new classification criteria. A major breakthrough has also occurred with respect to new biomarkers especially with the characterization of new autoantibody-antigen systems, which can be separated in myositis specific antibodies and myositis associated antibodies. These markers are detectable in approximately 80% of patients and facilitate not only the diagnostic procedures, but provide also important information on stratification of patients with respect to organ involvement, risk of cancer and overall prognosis of disease. Therefore, it is not only of importance to know the significance of these markers and to be familiar with the optimal diagnostic tests, but also with potential limitations in detection. This article focuses mainly on antibodies which are specific for myositis providing an overview on the targeted antigens, the available detection procedures and clinical association. As major tasks for the near future, the need of an international standardization is discussed for detection methods of autoantibodies in idiopathic inflammatory myopathies. Furthermore, additional investigations are required to improve stratification of patients with idiopathic inflammatory myopathies according to their antibody profile with respect to response to different treatment options.

Interferon Chemokine Score and Other Cytokine Measures Track With Changes in Disease Activity in Patients With Juvenile and Adult Dermatomyositis

Objective

Our aim was to identify cytokines and chemokines in patients with adult dermatomyositis (DM) and juvenile dermatomyositis (JDM) that predict changes in disease activity.

Methods

Multiplexed immunoassays (Meso Scale Discovery) enabled simultaneous measurement of interferon (IFN)‐regulated chemokines and other pro‐ and anti‐inflammatory cytokines specific to differentiation of specific T‐cell and innate pathways. Cytokine scores were computed for IFNCK (IP‐10, MCP‐1), Th1 (IFNɣ, TNFα, and IL2), Th2 (IL4, IL10, IL12, and IL 13), Th17 (IL6, IL17, IL1β), macrophage (MIP‐1α, MIP‐1β, IL8), and regulatory (IL10, TNFα) factors. Spearman correlation and mixed models were used to examine whether cytokines at a previous visit predict change in disease activity at the next visit.

Results

The study included 36 patients (16 DM and 20 JDM) with at least two visits (87 patient intervals between two visits). Mean age (SD) at inclusion was 56.9 (18.4) years for DM and 10.8 (6.6) years in JDM, 67% of patients were female, 89% Caucasian. The mean (SD) physician global, muscle and extra‐muscular disease activity Visual Analog Scale scores at inclusion were 41 (26), 36 (30), and 34 (21) mm, respectively. The change in IFN score from one visit to the next was associated with the change in physician global (P = 0.010) and extramuscular (P < 0.001) disease activity scores. Preliminary results revealed significant correlations of previous IFNCK score and IL‐6 with subsequent disease activity measures, but after adjustment for multiple visits per patient, these associations did not reach statistical significance.

Conclusion

There is a potential relationship between IFNCK and other cytokine scores seen in adult and juvenile DM with future disease states.

A Path to Prediction of Outcomes in Juvenile Idiopathic Inflammatory Myopathy

Humans have an innate desire to observe and subsequently dissect an event into component pieces in an effort to better characterize the event. We then examine these pieces individually and in combinations using this information to determine the outcome of future similar events and the likelihood of their recurrence. Practically, this attempt to foretell an occurrence and predict its outcomes is evident in multiple disciplines ranging from meteorology to sociologic studies. In this manuscript we share the historical and present-day tools to predict course and outcome in juvenile idiopathic inflammatory myopathy including clinical features, testing, and biomarkers. Further we discuss considerations for building more complex predictive models of outcome especially in diseases such as juvenile idiopathic inflammatory myopathy where patients numbers are low. Many of the barriers to developing risk prediction models for juvenile idiopathic inflammatory myopathy outcomes have improved with many remaining challenges being addressed.

Juvenile Dermatomyositis: A Case Report and Review of Literature

Juvenile dermatomyositis (JDM) is a systemic inflammatory disease involving children, which primarily affects the skin and the musculoskeletal system. The characteristic findings include Gottron papules, heliotrope rash, calcinosis cutis, and symmetric proximal muscle weakness. Histologically, it is characterized by the presence of lymphocytic vascular inflammation and endothelial swelling. Herein, we report a case of a 10-year-old girl of Indian origin, who presented to us with classical clinical and histological features of JDM.

Systemic and Tissue Inflammation in Juvenile Dermatomyositis: From Pathogenesis to the Quest for Monitoring Tools

Juvenile Dermatomyositis (JDM) is a systemic immune-mediated disease of childhood, characterized by muscle weakness, and a typical skin rash. Other organ systems and tissues such as the lungs, heart, and intestines can be involved, but may be under-evaluated. The inflammatory process in JDM is characterized by an interferon signature and infiltration of immune cells such as T cells and plasmacytoid dendritic cells into the affected tissues. Vasculopathy due to loss and dysfunction of endothelial cells as a result of the inflammation is thought to underlie the symptoms in most organs and tissues. JDM is a heterogeneous disease, and several disease phenotypes, each with a varying combination of affected tissues and organs, are linked to the presence of myositis autoantibodies. These autoantibodies have therefore been extensively studied as biomarkers for the disease phenotype and its associated prognosis. Next to identifying the JDM phenotype, monitoring of disease activity and disease-inflicted damage not only in muscle and skin, but also in other organs and tissues, is an important part of clinical follow-up, as these are key determinants for the long-term outcomes of patients. Various monitoring tools are currently available, among which clinical assessment, histopathological investigation of muscle and skin biopsies, and laboratory testing of blood for specific biomarkers. These investigations also give novel insights into the underlying immunological processes that drive inflammation in JDM and suggest a strong link between the interferon signature and vasculopathy. New tools are being developed in the quest for minimally invasive, but sensitive and specific diagnostic methods that correlate well with clinical symptoms or reflect local, low-grade inflammation. In this review we will discuss the types of (extra)muscular tissue inflammation in JDM and their relation to vasculopathic changes, critically assess the available diagnostic methods including myositis autoantibodies and newly identified biomarkers, and reflect on the immunopathogenic implications of identified markers.

Characteristics and predictors of malignancy in dermatomyositis: Analysis of 239 patients from northern China

The present study aimed to determine the characteristics of patients with dermatomyositis (DM) in order to identify predictors of cancer in these patients. Data of 239 patients with DM, treated at Yuhuangding Hospital between 1997 and 2016, was retrospectively assessed. The patients' demographic, clinical, survival and laboratory data were analyzed. Of the 239 patients, 43 developed malignancies. In 30 (69.77%) patients, the malignancy was detected within 1 year before or after DM diagnosis. There were 15 (34.88%) fatalities. Lung cancer was the most common type of malignancy identified (n=6, 13.95%), and adenocarcinoma was the most common pathological type (n=6, 13.95%). Older age, absence of interstitial lung disease, and absence of arthralgia were demonstrated to be independent risk factors for malignancy. Myositis-specific autoantibody expression, specifically anti-TIF1γ positivity and/or anti-MDA5 negativity, was associated with cancer in patients with DM. The survival rate was significantly lower in patients with malignancy than in patients without malignancy. Patients with DM had a high incidence of malignancy and a poor prognosis. Lung cancer and adenocarcinoma are common among patients with DM in northern China. Cancer screening should be conducted in all DM patients, particularly within 1 year of DM diagnosis. Older age is a risk factor for malignancy in DM patients, while interstitial lung disease and arthralgia are protective factors. Myositis-specific autoantibody detection may be useful for cancer screening in patients with DM.

Juvenile dermatomyositis forty years on: Case report

We present a case report of a 42 year old female, diagnosed at the age of 3 with Juvenile Dermatomyositis. The clinical course was severe and refractory to immunosuppressive therapy. Currently, she is mostly affected by severe muscle atrophy, large joint contractures, calcinosis, and a lipodystrophy associated metabolic syndrome with hypertriglyceridemia, insulin resistance, high total testosterone and hepatic steatosis. She developed Hodgkin´s lymphoma in the course of her disease. Personalized therapeutic choices are discussed as regards juvenile dermatomyositis complications.

The utility of comprehensive autoantibody testing to differentiate connective tissue disease associated and idiopathic interstitial lung disease subgroup cases

Interstitial lung disease (ILD) comprises many heterogeneous disease groups, the largest being CTD-associated and those labelled as idiopathic out of necessity. The mechanisms causing ILD are poorly understood, but most CTD- and idiopathic-ILD cases can respond to immunosuppression, clearly suggesting a pathological role for inflammation. By contrast, corticosteroid immunosuppression causes harm without benefit in the feared idiopathic pulmonary fibrosis, suggesting that inflammation plays little pathological role, and where ILD progresses rapidly to lethal outcome even with anti-fibrotic drug use. Given the treatment response differences apparent between ILD subgroups, and the dangers and costs of corticosteroid and anti-fibrotic drug use, respectively, it has become vital in every ILD patient to make an accurate subgroup diagnosis, to optimize treatment selections. This review discusses why differentiating CTD- and idiopathic-ILD subgroup cases remains so problematic, and why existing comprehensive CTD-specific serology would, if generally available, represent an ideal biomarker tool to enhance ILD subgroup diagnostic accuracy.

Mechanisms of Autoantibody-Induced Pathology

Autoantibodies are frequently observed in healthy individuals. In a minority of these individuals, they lead to manifestation of autoimmune diseases, such as rheumatoid arthritis or Graves' disease. Overall, more than 2.5% of the population is affected by autoantibody-driven autoimmune disease. Pathways leading to autoantibody-induced pathology greatly differ among different diseases, and autoantibodies directed against the same antigen, depending on the targeted epitope, can have diverse effects. To foster knowledge in autoantibody-induced pathology and to encourage development of urgently needed novel therapeutic strategies, we here categorized autoantibodies according to their effects. According to our algorithm, autoantibodies can be classified into the following categories: (1) mimic receptor stimulation, (2) blocking of neural transmission, (3) induction of altered signaling, triggering uncontrolled (4) microthrombosis, (5) cell lysis, (6) neutrophil activation, and (7) induction of inflammation. These mechanisms in relation to disease, as well as principles of autoantibody generation and detection, are reviewed herein.

Lupus pathobiology based on genomics

Systemic lupus erythematosus (SLE) is an autoimmune disorder with complex genetic underpinnings. This review attempts to assemble the myriad of genomic findings to build a clearer picture of the pathobiology of SLE to serve as a guide for therapeutics. Over 100 genes are now known for SLE, and several more penetrant ones have led to the emergence of more defined lupus phenotypes. Also discussed here are the targeted therapies that have come up on the horizon and the specific biologic mechanisms of more traditional therapies which have only recently been explored. The diagnostic toolbox has been enhanced by the addition of new antibodies, gene expression signatures, and mutation panels. This provides an opportunity to piece together the lupus puzzle and even revisit the clinical classification of SLE.

Systematic protein-protein interaction and pathway analyses in the idiopathic inflammatory myopathies

BACKGROUND

The idiopathic inflammatory myopathies (IIM) are autoimmune diseases characterised by acquired proximal muscle weakness, inflammatory cell infiltrates in muscle and myositis-specific/associated autoantibodies. It is unclear which pathways are involved in IIM, and the functional relationship between autoantibody targets has not been systematically explored. Protein-protein interaction and pathway analyses were conducted to identify pathways relevant to disease, using autoantibody targets and gene products of IIM-associated single nucleotide polymorphism (SNP) loci.

METHODS

Protein-protein interactions were analysed using Disease Association Protein-Protein Link Evaluator (DAPPLE). Gene ontology and pathway analyses were conducted using Database for Annotation Visualisation and Integrated Discovery (DAVID) and Gene Relationships Across Implicated Loci (GRAIL). Analyses were undertaken including the targets of published autoantibodies, significant and suggestive SNPs from an IIM association study and autoantibody targets plus SNPs combined.

RESULTS

The protein-protein interaction networks formed by autoantibody targets and associated SNPs showed significant direct and/or indirect connectivity (p < 0.05). Autoantibody targets plus associated SNPs combined resulted in more significant indirect and common interactor connectivity, suggesting autoantibody targets and proteins encoded by IIM-associated loci may be involved in common pathways. Tumour necrosis factor receptor-associated factor 6 (TRAF6) was identified as a hub protein, and UBE3B, HSPA1A, HSPA1B and PSMD3 also were identified as genes with significant connectivity. Pathway analysis identified that autoantibody targets and associated SNP regions are significantly interconnected (p < 0.01), and confirmed autoantibody target involvement in translational and post-translational processes. 'Ubiquitin' was the only keyword strongly linking significant genes across regions in all three GRAIL analyses of autoantibody targets and IIM-associated SNPs.

CONCLUSIONS

Autoantibody targets and IIM-associated loci show significant connectivity and inter-relatedness, and identify several key genes and pathways in IIM pathogenesis, possibly mediated via the ubiquitination pathway.

Comparing and contrasting clinical and serological features of juvenile and adult-onset myositis: implications for pathogenesis and outcomes

PURPOSE OF REVIEW

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.

RECENT FINDINGS

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.

SUMMARY

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.

Myositis-specific autoantibodies: an important tool to support diagnosis of myositis

The idiopathic inflammatory myopathies are characterized by muscle weakness, skin disease and internal organ involvement. Autoimmunity is known to have a role in myositis pathogenesis, and myositis-specific autoantibodies, targeting important intracellular proteins, are regarded as key biomarkers aiding in the diagnosis of patients. In recent years, a number of novel myositis autoantibodies including anti-TIF1, anti-NXP2, anti-MDA5, anti-SAE, anti-HMGCR and anti-cN1A have been identified in both adult and juvenile patients. These autoantibodies correlate with distinct clinical manifestations and importantly are found in inclusion body, statin-induced, clinically amyopathic and juvenile groups of myositis patients, previously believed to be mainly autoantibody negative. In this review, we will describe the main myositis-specific and myositis-associated autoantibodies and their frequencies and clinical associations across different ages and ethnic groups. We will also discuss preliminary studies investigating correlations between specific myositis autoantibody titres and clinical markers of disease course, collectively demonstrating the utility of myositis autoantibodies as both diagnostic and prognostic markers of disease.

Role of Jo-1 in the Immunopathogenesis of the Anti-synthetase Syndrome

Histidyl-tRNA synthetase (HRS = Jo-1) represents a key autoantibody target in the anti-synthetase syndrome that is marked by myositis as well as extra-muscular organ complications including interstitial lung disease (ILD). Over the last 25 years, a wealth of clinical, epidemiological, genetic, and experimental data have collectively supported a role for Jo-1 in mediating deleterious cell-mediated, adaptive immune responses contributing to the disease phenotype of the anti-synthetase syndrome. Complementing these studies, more recent work suggests that unique, non-enzymatic functional properties of Jo-1 also endow this antigen with the capacity to activate components of the innate immune system, particularly cell surface as well as endosomal Toll-like receptors and their downstream signaling pathways. Combining these facets of Jo-1-mediated immunity now supports a more integrated model of disease pathogenesis that should lead to improved therapeutic targeting in the anti-synthetase syndrome and related subsets of idiopathic inflammatory myopathy.

Pure White Cell Aplasia and Necrotizing Myositis

Pure white cell aplasia (PWCA) is a rare hematologic disorder characterized by the absence of neutrophil lineages in the bone marrow with intact megakaryopoiesis and erythropoiesis. PWCA has been associated with autoimmune, drug-induced, and viral exposures. Here, we report a case of a 74-year-old female who presented with severe proximal weakness without pain and was found to have PWCA with nonspecific inflammatory necrotizing myositis and acute liver injury on biopsies. These findings were associated with a recent course of azithromycin and her daily use of a statin. Myositis improved on prednisone but PWCA persisted. With intravenous immunoglobulin and granulocyte-colony stimulating factor therapies, her symptoms and neutrophil counts improved and were sustained for months.

A New Immunodot Assay for Multiplex Detection of Autoantibodies in a Cohort of Italian Patients With Idiopathic Inflammatory Myopathies

BACKGROUND

Autoantibody detection has been assessed as tool for the diagnosis and the definition of idiopathic inflammatory myopathies (IIM). The aim of the study was to characterize the autoantibody profiling of a cohort of Italian patients with IIM.

METHODS

Sera of 53 adult patients with definite IIM, according to Bohan-Peter criteria, were tested for anti-nuclear autoantibodies (ANA), using indirect immunofluorescence (IIF) method, and for myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs), using two new commercial immunodot assays.

RESULTS

MSAs and/or MAAs were detected in 29 of 53 (54.7%) patients with IIM. Twenty-three patients (43.4%) were positive for at least one MSAs: 13 (24.5%) had anti-histidyl-tRNA synthetase autoantibodies (Jo1), 4 (7.5%) had other anti-aminoacyl-tRNA synthetases autoantibodies (anti-ARS), 1 (1.8%) had anti-transcription intermediary factor 1 gamma autoantibodies (anti-TIF1γ), 2 (3.7%) had anti-nuclear helicase protein Mi-2 autoantibodies (anti-Mi-2), 4 (7.5%) had anti-small ubiquitin like modifier activating enzyme heterodimer autoantibodies (anti-SAE). Moreover, 17 patients (32%) were positive for at least one MAAs. Coexisting MSAs and MAAs were observed in 9 of 53 (16.9%) patients, anti-Jo1/SS-A autoantibodies in most cases. Overall sensitivity of immunodot assays was 54.7%, the specificity was almost absolute. At cut-off value of 1:160, the sensitivity of ANA-IIF was 52.8%, increasing to 66% if cytoplasmatic fluorescence reaction was reported. Notably, two (5.7%) ANA-IIF negative patients had MSAs, detected only by immunodot assays.

CONCLUSION

It was possible to identify MSAs otherwise undetectable because of the use of new assays. Immunodot can reveal MSAs even when IIF results are inconclusive or, in some cases, ANA negative.

An Autopsy Case of Anti-melanoma Differentiation-associated Gene-5 Antibody-positive Clinical Amyopathic Dermatomyositis Complicated by Rapidly Progressive Interstitial Lung Disease

A 62-year-old man presented with heliotrope rash, Gottron's sign, and mild muscle weakness. Both of his lung fields showed interstitial changes that worsened rapidly. He was diagnosed with clinical amyopathic dermatomyositis with rapidly progressive interstitial lung disease. The patient died of respiratory failure, despite the administration of immunosuppressive therapy. Autopsy revealed diffuse alveolar damage. An antibody analysis, which was performed postmortem, detected the presence of anti-melanoma differentiation-associated gene (MDA)-5 antibodies. Clinicians should note the clinical, radiologic, and serologic findings to predict anti-MDA-5 antibody-associated rapidly progressive interstitial lung disease.

Serological subsets of juvenile idiopathic inflammatory myopathies--an update

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.

[Juvenile dermatomyositis and new autoantibodies: Cases and review]

Juvenile dermatomyositis (JDM) is the most common inflammatory myopathy in children. Its diagnosis is usually made on a clinical basis following the criteria of Bohan and Peter (1975). Recently, the presence of myositis-specific autoantibodies (MSAs) have started to be associated with specific outcome in adult patients; the diagnosis and prognosis value of these autoantibodies remains to be identified in children. We report four cases of JDM with MSAs focusing on clinical, biological, and radiological manifestations, and then we describe associated treatment. The cohort comprises four girls with an average age of 8.5 years. The time to diagnosis was 1 week to 4 months. For these patients, the immunologic study found one patient positive for the MDA5 antibody (or CADM 140), one positive for the TIF1γ antibody (or p155/140), and two patients positive for the NXP2 antibody (or p140/MJ). Each patient showed specific and characteristic cutaneous manifestations. For example, the girl positive for the TIF1γ antibody presented the most severe skin disease with urticaria, face edema, and vascularity of the neck and shoulders. However, regarding muscular features, proximal weakness was present in most of the cohort, except for the child positive for the MDA5 antibody, who presented no sign of muscular disease at the beginning with low CK levels. Importantly, acute pancreatitis also affected this patient. Concerning radiological indications, muscular MRI evidenced hyperinflammation, a sign of diffuse myositis, in all these patients. Treatments consisted in corticosteroids together with methotrexate or mycofenolate mofetil associated or not with intravenous immunoglobulin therapy. This report highlights the importance of systematic detection and analysis of MSA in diagnosis and characterization of JDM, and describes a new approach that would allow more focused treatments and be a useful predictor of clinical complications and prognosis in JDM-affected subjects.

Development of autoantibodies against muscle-specific FHL1 in severe inflammatory myopathies

Mutations of the gene encoding four-and-a-half LIM domain 1 (FHL1) are the causative factor of several X-linked hereditary myopathies that are collectively termed FHL1-related myopathies. These disorders are characterized by severe muscle dysfunction and damage. Here, we have shown that patients with idiopathic inflammatory myopathies (IIMs) develop autoimmunity to FHL1, which is a muscle-specific protein. Anti-FHL1 autoantibodies were detected in 25% of IIM patients, while patients with other autoimmune diseases or muscular dystrophies were largely anti-FHL1 negative. Anti-FHL1 reactivity was predictive for muscle atrophy, dysphagia, pronounced muscle fiber damage, and vasculitis. FHL1 showed an altered expression pattern, with focal accumulation in the muscle fibers of autoantibody-positive patients compared with a homogeneous expression in anti-FHL1-negative patients and healthy controls. We determined that FHL1 is a target of the cytotoxic protease granzyme B, indicating that the generation of FHL1 fragments may initiate FHL1 autoimmunity. Moreover, immunization of myositis-prone mice with FHL1 aggravated muscle weakness and increased mortality, suggesting a direct link between anti-FHL1 responses and muscle damage. Together, our findings provide evidence that FHL1 may be involved in the pathogenesis not only of genetic FHL1-related myopathies but also of autoimmune IIM. Importantly, these results indicate that anti-FHL1 autoantibodies in peripheral blood have promising potential as a biomarker to identify a subset of severe IIM.

Idiopathic inflammatory myopathies: from immunopathogenesis to new therapeutic targets

Pathogenesis of idiopathic inflammatory myositis (IIM) involves strong interactions between dendritic cells (DCs), activated Th1 and Th17 cells, B cells, muscle cells, genes and environment. Local maturation of DCs permit the activation and polarization of CD4+ T cells into T(H)1 and T(H)17 that play a key role in maintaining chronic muscle inflammation. T-cell mediated myocytotoxicity promotes the liberation of specific muscle autoantigens from regenerating muscle cells with production of myositis-specific autoantibodies. Type I interferon signature is a key characteristic of IIM. Type I IFN that can be induced by immune complexes containing myositis-specific autoantibodies is produced by scattered plasmacytoid DCs but also by muscle cells particularly regenerating muscle cells. These immature muscle precursors appear to be critical in the pathogenesis of IIM as they up-regulate muscle autoantigens, type I IFN, HLA class I antigens and TLR3-7, all together involved in maintaining chronic muscle inflammation. In addition to the role of immune and muscle cells, genome-wide association studies have confirmed the importance of several MHC and non-MHC genes in IIM. Environmental factors can contribute to the pathogenesis of IIM. In sIBM, distinct features suggest both degenerative and inflammatory processes. In addition to our better understanding of the pathogenesis, identify molecular pathway leads to consider new targeted therapies including cytokine inhibition, B-cell and T-cell costimulation blockade, type I IFN neutralization or inhibition of the ubiquitin proteasome pathway.

Recent advances in juvenile idiopathic inflammatory myopathies

PURPOSE OF REVIEW

Ongoing research continues to advance our understanding of the juvenile idiopathic inflammatory myopathies (JIIMs). We review the recent contributions from the published literature about the classification, pathogenesis, assessment, and treatment of JIIMs in basic and translational science and clinical research in 2013 through early 2014.

RECENT FINDINGS

Large registries, such as the Childhood Arthritis and Rheumatology Research Alliance registry, are conducting trials to enhance our understanding of JIIMs. Ultraviolet radiation exposure 1 month prior to juvenile dermatomyositis (JDM) may trigger the onset of disease. Myositis-specific autoantibodies define clinical phenotypes in JIIMs. MRI is useful in diagnosing JDM and may be used as a disease assessment tool. Type 1 interferon genes and proteins are increasing in use as disease assessment tools, but larger, prospective, validation studies are needed. Moderate-to-intense physical activity is effective in increasing the aerobic capacity of JDM patients in remission. New criteria developed by the Paediatric Rheumatology International Trials Organization for classifying inactive disease in JDM have practical applicability to the current clinical practice and clinical trials as even after 16.8 years of symptom onset, over half of JDM patients still have active disease.

SUMMARY

There has been significant progress in understanding the clinical characteristics, diagnostic workup, treatment, disease assessment, and prognosis of JIIM patients, but more prospective treatment trials are needed, especially in light of the paucity of the current biologic treatment agents available.

Innate immune-response mechanisms in dermatomyositis: an update on pathogenesis, diagnosis and treatment

Dermatomyositis (DM) is an autoimmune disease mainly affecting muscle and skin. Typical clinical and laboratory findings include muscle weakness with elevated muscle enzymes, characteristic skin lesions (e.g., Gottron papules, heliotrope erythema, Shawl sign), and specific serum autoantibodies. Recent studies have highlighted the activation of the innate immune system, including high expression of interferons (IFNs) and IFN-regulated proteins, as an important pathological hallmark of DM. These findings have changed our understanding of the disease fundamentally, since inappropriate activation of the innate immune system with secondary dysregulation of the adaptive immune response is now considered to be a central pathogenetic feature of DM. In this article, we review current guidelines and standards in diagnosis and treatment. We detail evidence-based and pathophysiology-based treatment strategies, with a focus on skin as well as on muscle lesions. Particularly, we discuss how the recent advances in the understanding of the pathomechanisms of DM have altered our conception of the mode of action of established drugs such as chloroquine and methotrexate. Finally, we outline possible future treatment strategies, with a focus on the innate immune system, e.g., targeting the IFN system with the anti-IFN-α antibody sifalimumab.

Distinctive cutaneous and systemic features associated with antitranscriptional intermediary factor-1γ antibodies in adults with dermatomyositis

BACKGROUND

Antibodies against transcriptional intermediary factor (TIF)-1γ are associated with malignancy in dermatomyositis (DM). Identification of clinical findings associated with anti-TIF-1γ antibodies in DM is a high priority for both patient diagnosis and risk assessment.

OBJECTIVE

We sought to define the clinical phenotype of patients with anti-TIF-1γ DM.

METHODS

Using a novel, sensitive, and specific assay for anti-TIF-1γ antibodies, we retrospectively tested plasma from 134 adult patients with DM and examined associations between anti-TIF-1γ antibodies and particular clinical and laboratory features.

RESULTS

In all, 55 (41%) patients had autoantibodies to TIF-1γ. Anti-TIF-1γ positive patients were less likely to have systemic features including interstitial lung disease, Raynaud phenomenon, and arthritis/arthralgia. Patients with TIF-1γ autoantibodies had more extensive skin involvement, and some patients manifested characteristic findings including palmar hyperkeratotic papules, psoriasis-like lesions and a novel finding of hypopigmented and telangiectatic ("red on white") patches.

LIMITATIONS

This was a retrospective study from a single tertiary referral center.

CONCLUSION

TIF-1γ is the most commonly targeted DM-specific autoantigen in adults in a large US cohort. Although these patients tend to have less systemic involvement, their skin disease is often extensive and characteristic. Recognition of cutaneous findings in anti-TIF-1γ positive patients may allow more accurate and timely diagnosis and effective treatment of patients with DM.

[Dermatomyositis-specific antibodies]

BACKGROUND

Idiopathic inflammatory myopathies are chronic systemic autoimmune diseases characterized by symmetrical proximal muscle weakness. The clinicopathological subdivision nowadays appears to be obsolete which is why the immunoserological classification has been developed.

OBJECTIVES

Dermatomyositis represents one the most important subsets of idiopathic inflammatory myopathy and dermatomyositis-specific autoantibodies play a significant role in this subset. The aim of this article was to present these autoantibodies with the help of the literature.

METHODS

This article presents the most important information about dermatomyositis including not only the classical anti-Mi-2 autoantibody but also the recently detected anti-TIF1γ, anti-NXP2, anti-SAE and anti-MDA5 autoantibodies. The focus is on the frequency of these autoantibodies, the associated symptoms in adult and juvenile dermatomyositis cases and some special aspects from the literature.

RESULTS

All of the studies confirmed that these autoantibodies are particularly detectable in dermatomyositis. The results from the literature have recently shown that the frequency of the autoantibodies detected in juvenile cases is higher than the frequency of traditional autoantibodies (e.g. anti-Jo-1, anti-Mi-2 and anti-SRP).

CONCLUSION

It is useful to detect these autoantibodies in order to be able to make a better assessment of the clinical symptoms and prognosis during the course of the disease.

Myositis registries and biorepositories: powerful tools to advance clinical, epidemiologic and pathogenic research

PURPOSE OF REVIEW

Clinical registries and biorepositories have proven extremely useful in many studies of diseases, especially rare diseases. Given their rarity and diversity, the idiopathic inflammatory myopathies, or myositis syndromes, have benefited from individual researchers' collections of cohorts of patients. Major efforts are being made to establish large registries and biorepositories that will allow many additional studies to be performed that were not possible before. Here, we describe the registries developed by investigators and patient support groups that are currently available for collaborative research purposes.

RECENT FINDINGS

We have identified 46 myositis research registries, including many with biorepositories, which have been developed for a wide variety of purposes and have resulted in great advances in understanding the range of phenotypes, clinical presentations, risk factors, pathogenic mechanisms, outcome assessment, therapeutic responses, and prognoses. These are now available for collaborative use to undertake additional studies. Two myositis patient registries have been developed for research, and myositis patient support groups maintain demographic registries with large numbers of patients available to be contacted for potential research participation.

SUMMARY

Investigator-initiated myositis research registries and biorepositories have proven extremely useful in understanding many aspects of these rare and diverse autoimmune diseases. These registries and biorepositories, in addition to those developed by myositis patient support groups, deserve continued support to maintain the momentum in this field as they offer major opportunities to improve understanding of the pathogenesis and treatment of these diseases in cost-effective ways.