The juvenile idiopathic inflammatory myopathies: pathogenesis, clinical and autoantibody phenotypes, and outcomes

Value of radiomics-based automatic grading of muscle edema in polymyositis/dermatomyositis based on MRI fat-suppressed T2-weighted images

BACKGROUND

The precise and objective assessment of thigh muscle edema is pivotal in diagnosing and monitoring the treatment of dermatomyositis (DM) and polymyositis (PM).

PURPOSE

Radiomic features are extracted from fat-suppressed (FS) T2-weighted (T2W) magnetic resonance imaging (MRI) of thigh muscles to enable automatic grading of muscle edema in cases of polymyositis and dermatomyositis.

MATERIAL AND METHODS

A total of 241 MR images were analyzed and classified into five levels using the Stramare criteria. The correlation between muscle edema grading and T2-mapping values was assessed using Spearman's correlation. The dataset was divided into a 7:3 ratio of training (168 samples) and testing (73 samples). Thigh muscle boundaries in FS T2W images were manually delineated with 3D-Slicer. Radiomics features were extracted using Python 3.7, applying Z-score normalization, Pearson correlation analysis, and recursive feature elimination for reduction. A Naive Bayes classifier was trained, and diagnostic performance was evaluated using receiver operating characteristic (ROC) curves and comparing sensitivity and specificity with senior doctors.

RESULTS

A total of 1198 radiomics parameters were extracted and reduced to 18 features for Naive Bayes modeling. In the testing set, the model achieved an area under the ROC curve of 0.97, sensitivity of 0.85, specificity of 0.98, and accuracy of 0.91. The Naive Bayes classifier demonstrated grading performance comparable to senior doctors. A significant correlation (r = 0.82, P <0.05) was observed between Stramare edema grading and T2-mapping values.

CONCLUSION

The Naive Bayes model, utilizing radiomics features extracted from thigh FS T2W images, accurately assesses the severity of muscle edema in cases of PM/DM.

Updates on efficacy and safety janus kinase inhibitors in juvenile dermatomyositis

INTRODUCTION

Juvenile dermatomyositis (JDM) is a rare autoimmune disease most commonly with proximal weakness due to inflammation and characteristic skin rashes. Most patients have a chronic or polycyclic disease course on standard therapy so better treatments are needed. An interferon signature is well-established in key tissues of JDM. Janus kinase inhibitors (jakinibs), which can decrease IFN signaling, are therefore appealing as a targeted therapy.

AREAS COVERED

Herein is a review of the growing literature on JDM patients in jakinibs, including specifics of their jakinib exposure, summary of efficacy, disease features, and characteristics of patients treated, and safety parameters.

EXPERT OPINION

The vast majority of refractory JDM patients respond to jakinib therapy, though they have varied features, doses, and previous/concurrent medications, and data is largely retrospective. Jakinibs are an exciting and promising treatment in JDM. Evaluation with larger prospective controlled studies is needed to answer remaining questions about jakinibs in JDM regarding dosing, which JDM patients to treat with jakinibs, potential biomarkers to use, and how best to monitor safety risks in JDM.

Successful treatment with tofacitinib for anti-melanoma differentiation-associated gene 5 antibody-positive juvenile dermatomyositis: case reports and review of the literature

Although the clinical efficacy of tofacitinib has been reported in adult patients with anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive (Ab+) dermatomyositis, data on its use in refractory juvenile dermatomyositis (JDM) are scarce. We describe two female Japanese patients with anti-MDA5 Ab + JDM and rapidly progressive interstitial lung disease who achieved remission by adding tofacitinib to existing immunosuppressive drugs and present a literature review. While both patients received various immunosuppressive or anti-inflammatory treatments for induction therapy, remission could not be achieved. Subsequently, tofacitinib was administered to reduce the Krebs von den Lungen-6 level 5 months after diagnosis in one patient; the other patient received tofacitinib 4 months after diagnosis to reduce ferritin levels and skin manifestations. Subsequently, both patients achieved remission, and prednisolone was withdrawn. Tofacitinib reduced the interferon signature associated with dermatomyositis/JDM disease progression and exerted a therapeutic effect on dermatomyositis/JDM. We found six published cases from five articles of tofacitinib for refractory anti-MDA5 Ab + JDM. Except for one case of herpes simplex meningitis, the other cases, including ours, had improved disease activity without severe adverse events, and steroids and immunosuppressive medicines could be tapered. Tofacitinib could be considered an available therapy for refractory anti-MDA5 Ab + JDM.

Juvenile dermatomyositis with central nervous system involvement: two case reports from a retrospective single-center cohort, with literature review

Background

Juvenile dermatomyositis (JDM) is a systemic autoimmune disease primarily involving the muscles and skin; it can also affect the central nervous system (CNS). The relevant literature provides limited information regarding the characteristics of JDM with CNS involvement.

Method

We reviewed patients with JDM who were hospitalized at our center between January 2016 and August 2023, with a focus on those with CNS involvement. The aim was to provide detailed case reports on these patients, and to summarize the relevant literature about the characteristics of similar cases.

Results

Among 193 hospitalized patients with JDM, two (1.03%) had CNS involvement. Two patients, a 5.5-year-old girl and an 11-year-old boy, were admitted with severe proximal muscle weakness and seizures, and presented with active cutaneous vasculitis. Both were ultimately diagnosed with JDM, with CNS involvement. Both patients had confirmed presence of anti-NXP2 antibody through myositis-specific antibody analysis. Additionally, they all exhibited hyperferritinemia and thrombocytopenia. Salvage therapies like intravenous methylprednisolone (IVMP) pulse therapy and/or plasma exchange were administered successfully. At final follow-up, both patients had achieved complete clinical response and full neurological recovery. Our literature review identified nine similar case studies. CNS involvement usually occurred within the first 10 months of the disease course, and most of these patients had fatal outcomes, with a mortality rate of 66.6% (6/9). Including the two patients described herein, the median age for disease onset is 10.5 years (range 4-17 years), and the male: female ratio is 6:5. Seizures are the most common neurological symptom, accompanied by active cutaneous vasculitis. The brain biopsies showed two distinct pathological presentations: one was central nervous system vasculitis, and the other was cerebral macrophage activation syndrome.

Conclusions

CNS involvement is a rare but life-threatening JDM complication. Herein, our cases and the literature indicate that it typically occurs within the first 10 months of the disease course and manifests as seizures, often accompanied by active cutaneous vasculitis, with fatal outcomes. Timely implementation of salvage therapies, like IVMP pulse therapy and plasma exchange, may significantly impact patient outcomes.

Effect of type I interferon on engineered pediatric skeletal muscle: a promising model for juvenile dermatomyositis

OBJECTIVE

To investigate pathogenic mechanisms underlying JDM, we defined the effect of type I IFN, IFN-α and IFN-β, on pediatric skeletal muscle function and expression of myositis-related proteins using an in vitro engineered human skeletal muscle model (myobundle).

METHODS

Primary myoblasts were isolated from three healthy pediatric donors and used to create myobundles that mimic functioning skeletal muscle in structural architecture and physiologic function. Myobundles were exposed to 0, 5, 10 or 20 ng/ml IFN-α or IFN-β for 7 days and then functionally tested under electrical stimulation and analyzed immunohistochemically for structural and myositis-related proteins. Additionally, IFN-β-exposed myobundles were treated with Janus kinase inhibitors (JAKis) tofacitinib and baricitinib. These myobundles were also analyzed for contractile force and immunohistochemistry.

RESULTS

IFN-β, but not IFN-α, was associated with decreased contractile tetanus force and slowed twitch kinetics. These effects were reversed by tofacitinib and baricitinib. Type I IFN paradoxically reduced myobundle fatigue, which did not reverse after JAKi. Additionally, type I IFN correlated with MHC I upregulation, which normalized after JAKi treatment, but expression of myositis-specific autoantigens Mi-2, melanocyte differentiation-associated protein 5 and the endoplasmic reticulum stress marker GRP78 were variable and donor specific after type I IFN exposure.

CONCLUSION

IFN-α and IFN-β have distinct effects on pediatric skeletal muscle and these effects can partially be reversed by JAKi treatment. This is the first study illustrating effective use of a three-dimensional human skeletal muscle model to investigate JDM pathogenesis and test novel therapeutics.

Can vitamin D be an adjuvant therapy for juvenile rheumatic diseases?

Vitamin D, known for its essential role in calcium and bone homeostasis, has multiple effects beyond the skeleton, including regulation of immunity and modulation of autoimmune processes. Several reports have shown suboptimal serum 25 hydroxyvitamin D [25(OH)D] levels in people with different inflammatory and autoimmune rheumatic conditions, and an association between 25(OH)D levels, disease activity and outcomes. Although most available data pertain to adults, insights often are extended to children. Juvenile rheumatic diseases (JRDs) are a significant health problem during growth because of their complex pathogenesis, chronic nature, multisystemic involvement, and long-term consequences. So far, there is no definitive or clear evidence to confirm the preventive or therapeutic effect of vitamin D supplementation in JRDs, because results from randomized controlled trials (RCTs) have produced inconsistent outcomes. This review aims to explore and discuss the potential role of vitamin D in treating selected JRDs. Medline/PubMed, EMBASE, and Scopus were comprehensively searched in June 2023 for any study on vitamin D supplementary role in treating the most common JRDs. We used the following keywords: "vitamin D" combined with the terms "juvenile idiopathic arthritis", "juvenile systemic scleroderma", "juvenile systemic lupus erythematosus", "juvenile inflammatory myopathies", "Behcet disease", "periodic fever syndromes" and "juvenile rheumatic diseases". Observational studies have found that serum 25(OH)D concentrations are lower in juvenile idiopathic arthritis, juvenile systemic lupus erythematosus, juvenile systemic scleroderma, Behcet disease and proinflammatory cytokine concentrations are higher. This suggests that vitamin D supplementation might be beneficial, however, current data are insufficient to confirm definitively the complementary role of vitamin D in the treatment of JRDs. Considering the high prevalence of vitamin D deficiency worldwide, children and adolescents should be encouraged to supplement vitamin D according to current recommendations. More interventional studies, especially well-designed RCTs, assessing the dose-response effect and adjuvant effect in specific diseases, are needed to determine the potential significance of vitamin D in JRDs treatment.

Impact of SARS-CoV-2 on the clinical presentation of juvenile idiopathic inflammatory myopathies

BACKGROUND

Growing evidence suggests that infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger idiopathic inflammatory myopathies (IIM). Few studies have described individual juvenile IIM (JIIM) cases following SARS-CoV-2 infection, and none explored its potential effects on JIIM clinical presentation. We aim to investigate the impact of SARS-CoV-2 on JIIM in patients diagnosed before and after the onset of the Coronavirus Disease 2019 (COVID-19) pandemic.

METHODS

Patients diagnosed with JIIM before age 19 at The Children's Hospital at Montefiore were included. Demographics, clinical and laboratory data, and evidence of SARS-CoV-2 exposure were collected retrospectively. Patients were grouped by pre-COVID-19 (before January 1, 2020) and post-COVID-19 (January 1, 2020, or later). Descriptive statistics were used to summarize each variable. Non-parametric testing was performed using Fischer's exact test and Mann-Whitney U test.

RESULTS

Fifty-one patients were included, 13 (25%) diagnosed in the post-COVID-19 era. Of these, 10 (77%) had onset of JIIM symptoms after January 1, 2020; 6 (60%) with known or suspected SARS-CoV-2 exposure. Though not statistically significant, post-pandemic patients tended to be older, female, and have non-specific cutaneous manifestations. Despite reported delays in care for other pediatric diagnoses during the pandemic, fewer post-pandemic patients had delays in JIIM diagnosis.

CONCLUSIONS

This is the first study to explore the effects of SARS-CoV-2 on JIIM clinical presentation. While our exploratory single-center study did not find significant differences in JIIM diagnosed pre- and post-pandemic, larger prospective multicenter studies are warranted to evaluate this association and to explore clinical variances over time.

Muscle fiber necroptosis in pathophysiology of idiopathic inflammatory myopathies and its potential as target of novel treatment strategy

Idiopathic inflammatory myopathies (IIMs), which are a group of chronic and diverse inflammatory diseases, are primarily characterized by weakness in the proximal muscles that progressively leads to persistent disability. Current treatments of IIMs depend on nonspecific immunosuppressive agents (including glucocorticoids and immunosuppressants). However, these therapies sometimes fail to regulate muscle inflammation, and some patients suffer from infectious diseases and other adverse effects related to the treatment. Furthermore, even after inflammation has subsided, muscle weakness persists in a significant proportion of the patients. Therefore, the elucidation of pathophysiology of IIMs and development of a better therapeutic strategy that not only alleviates muscle inflammation but also improves muscle weakness without increment of opportunistic infection is awaited. Muscle fiber death, which has been formerly postulated as "necrosis", is a key histological feature of all subtypes of IIMs, however, its detailed mechanisms and contribution to the pathophysiology remained to be elucidated. Recent studies have revealed that muscle fibers of IIMs undergo necroptosis, a newly recognized form of regulated cell death, and promote muscle inflammation and dysfunction through releasing inflammatory mediators such as damage-associated molecular patterns (DAMPs). The research on murine model of polymyositis, a subtype of IIM, revealed that the inhibition of necroptosis or HMGB1, one of major DAMPs released from muscle fibers undergoing necroptosis, ameliorated muscle inflammation and recovered muscle weakness. Furthermore, not only the necroptosis-associated molecules but also PGAM5, a mitochondrial protein, and reactive oxygen species have been shown to be involved in muscle fiber necroptosis, indicating the multiple target candidates for the treatment of IIMs acting through necroptosis regulation. This article overviews the research on muscle injury mechanisms in IIMs focusing on the contribution of necroptosis in their pathophysiology and discusses the potential treatment strategy targeting muscle fiber necroptosis.

Juvenile idiopathic inflammatory myositis: an update on pathophysiology and clinical care

The childhood-onset or juvenile idiopathic inflammatory myopathies (JIIMs) are a heterogenous group of rare and serious autoimmune diseases of children and young people that predominantly affect the muscles and skin but can also involve other organs, including the lungs, gut, joints, heart and central nervous system. Different myositis-specific autoantibodies have been identified that are associated with different muscle biopsy features, as well as with different clinical characteristics, prognoses and treatment responses. Thus, myositis-specific autoantibodies can be used to subset JIIMs into sub-phenotypes; some of these sub-phenotypes parallel disease seen in adults, whereas others are distinct from adult-onset idiopathic inflammatory myopathies. Although treatments and management have much improved over the past decade, evidence is still lacking for many of the current treatments and few validated prognostic biomarkers are available with which to predict response to treatment, comorbidities (such as calcinosis) or outcome. Emerging data on the pathogenesis of the JIIMs are leading to proposals for new trials and tools for monitoring disease.

Role of CD14+ monocyte-derived oxidised mitochondrial DNA in the inflammatory interferon type 1 signature in juvenile dermatomyositis

OBJECTIVES

To define the host mechanisms contributing to the pathological interferon (IFN) type 1 signature in Juvenile dermatomyositis (JDM).

METHODS

RNA-sequencing was performed on CD4+, CD8+, CD14+ and CD19+ cells sorted from pretreatment and on-treatment JDM (pretreatment n=10, on-treatment n=11) and age/sex-matched child healthy-control (CHC n=4) peripheral blood mononuclear cell (PBMC). Mitochondrial morphology and superoxide were assessed by fluorescence microscopy, cellular metabolism by 13C glucose uptake assays, and oxidised mitochondrial DNA (oxmtDNA) content by dot-blot. Healthy-control PBMC and JDM pretreatment PBMC were cultured with IFN-α, oxmtDNA, cGAS-inhibitor, TLR-9 antagonist and/or n-acetyl cysteine (NAC). IFN-stimulated gene (ISGs) expression was measured by qPCR. Total numbers of patient and controls for functional experiments, JDM n=82, total CHC n=35.

RESULTS

Dysregulated mitochondrial-associated gene expression correlated with increased ISG expression in JDM CD14+ monocytes. Altered mitochondrial-associated gene expression was paralleled by altered mitochondrial biology, including 'megamitochondria', cellular metabolism and a decrease in gene expression of superoxide dismutase (SOD)1. This was associated with enhanced production of oxidised mitochondrial (oxmt)DNA. OxmtDNA induced ISG expression in healthy PBMC, which was blocked by targeting oxidative stress and intracellular nucleic acid sensing pathways. Complementary experiments showed that, under in vitro experimental conditions, targeting these pathways via the antioxidant drug NAC, TLR9 antagonist and to a lesser extent cGAS-inhibitor, suppressed ISG expression in pretreatment JDM PBMC.

CONCLUSIONS

These results describe a novel pathway where altered mitochondrial biology in JDM CD14+ monocytes lead to oxmtDNA production and stimulates ISG expression. Targeting this pathway has therapeutical potential in JDM and other IFN type 1-driven autoimmune diseases.

Experience with the use of mycophenolate mofetil in juvenile idiopathic inflammatory myopathies

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of MMF in juvenile idiopathic inflammatory myopathies (JIIMs).

METHODS

Patients diagnosed with JIIM and treated with MMF enrolled in the Juvenile Dermatomyositis Research Group (JDRG) in the UK or followed at the Giannina Gaslini Institute in Genoa, Italy, were included. The following information was collected retrospectively at MMF initiation, at 3, 6 and 12 months after treatment start, and at last follow-up visit: clinical manifestations, laboratory data, physicians' subjective assessment of disease activity, standardized outcome measures of muscle strength/endurance, cutaneous disease activity, physical function, global disease activity, cumulative damage, and ongoing treatment.

RESULTS

Of the 29 patients included, 23 had juvenile DM and 6 had overlap myositis. During administration of MMF, improvement in measures of muscle strength, skin disease activity, and overall disease activity was seen, with an increase in the frequency of normal scores for Manual Muscle Test-8 from 50.0% to 83.3%, Childhood Myositis Activity Score from 53.5% to 88.9%, muscle component of DAS from 55.2% to 84.2%, skin component of DAS from 31.0% to 42.1%, visual analogue scale for skin disease activity from 25.0% to 47.4%, and visual analogue scale for overall disease activity from 7.1% to 42.1%. The number of patients with inactive disease increased from 10.3% at baseline to 68.5% at last follow-up. CS dose was significantly reduced, from 0.3 to 0.1 mg/kg/day. No relevant side effects were reported.

CONCLUSION

Our experience suggests that MMF is a valuable therapeutic option for the management of JIIM.

Clinical and autoantibody phenotypes of juvenile dermatomyositis

Juvenile dermatomyositis (JDM) is a heterogeneous autoimmune inflammatory myositis with symmetrical proximal muscle weakness and a characteristic rash. Juvenile dermatomyositis is characterized by variable presentation and phenotypes. Detection of myositis autoantibodies is useful in improving JDM diagnosis and predicting the prognosis. In this literature review based on case series we analyze clinical and autoantibody phenotypes of JDM in four patients who were hospitalized in one regional center in Ukraine during the last 3 years and three of them presented in the time of the COVID-19 pandemic. The reviewed literature showed the last updates for the JDM diagnosis and the role of myositis autoantibodies in the prediction of disease course, systemic involvement, and malignancy risk. The presence of anti-synthetase syndrome in all presented patients, mainly due to anti-PL-7 autoantibodies, encourages further study with more patients and with detection of other myositis-specific autoantibodies to identify or refute certain regional features.

Autoimmune and autoinflammatory diseases with mucocutaneous manifestations: A pediatric rheumatology perspective

The presence of mucocutaneous manifestations has clinical significance, as it may be a part of the initial presentation or activation stage of both autoimmune and autoinflammatory rheumatic diseases. The cutaneous signs may display a particular morphological and topographic distribution according to taxonomy, whereas heterogeneity is likely observed among the individuals. The review aims to cluster and systematically approach the mucocutaneous manifestations met in autoimmune and autoinflammatory rheumatic diseases of childhood. The search strategy involved a comprehensive inquiry on Web of Science, PubMed, MEDLINE, and Embase databases using relevant search terms such as "dermatologic, cutaneous, mucocutaneous, skin, rash" for each disease and category. The awareness of the distinctive mucocutaneous manifestations and their correlation with rheumatic diseases provides a convenient definition, well-timed control of the underlying condition, and prevention of cosmetic issues. In the management of rheumatic diseases, planning the pertinent differential diagnosis and determining the requirement of histopathological assessment are essential with a multidisciplinary approach to rheumatology, dermatology, and allergy-immunology specialties.

Gene Expression Profiles of Treatment Response and Non-Response in Children With Juvenile Dermatomyositis

Objective

The study objective was to identify differences in gene expression between treatment responders (TRs) and treatment non‐responders (TNRs) diagnosed with juvenile dermatomyositis (JDM).

Methods

Gene expression analyses were performed using whole blood messenger RNA sequencing in patients with JDM (n = 17) and healthy controls (HCs; n = 10). Four analyses were performed (A1‐4) comparing differential gene expression and pathways analysis exploiting the timing of sample acquisition and the treatments received to perform these comparative analyses. Analyses were done at diagnosis and follow‐up, which averaged 7 months later in the cohort.

Results

At diagnosis, the expression of 10 genes differed between TRs and TNRs. Hallmark and canonical pathway analysis revealed 11 and 60 pathways enriched in TRs and 3 and 21 pathways enriched in TNRs, respectively. Pathway enrichment at diagnosis in TRs was strongest in pathways involved in metabolism, complement activation, and cell signaling as mediated by IL‐8, p38/microtubule associated protein kinases (MAPK)/extracellular signal‐regulated kinases (ERK), Phosphatidylinositol 3 Kinase Gamma (PI3Kγ), and the B cell receptor. Follow‐up hallmark and canonical pathway analysis showed that 2 and 14 pathways were enriched in TRs, whereas 24 and 123 pathways were enriched in treatment TNRs, respectively. Prior treatment with glucocorticoids significantly altered expression of 13 genes in the analysis of subjects at diagnosis with JDM as compared with HCs.

Conclusion

Numerous genes and pathways differ between TRs and TNRs at diagnosis and follow‐up. Prior treatment with glucocorticoids prior to specimen acquisition had a small effect on the performed analyses.

Case Report: Simultaneously Developed Amyopathic Dermatomyositis and Autoimmune Sclerosing Cholangitis - a Coincidence or a Shared Immunopathogenesis?

Inflammatory rheumatic diseases (IRD) and autoimmune liver diseases (AILD) share many similarities regarding epidemiology, genetics, immunology and therapeutic regimens, so it is not surprising that approximately 20% of patients with AILD are diagnosed with an IRD as well. Clinical features and biochemical hallmarks of IRD and AILD often intertwine and cross diagnostic criteria. Therefore, the real distinction of underlying disorders in a patient with these comorbidities may be challenging. The present report is the first report of simultaneously developed juvenile dermatomyositis (JDM) and autoimmune sclerosing cholangitis (ASC) with both entities fulfilling the latest guidelines for a definite diagnosis. Both of these diagnoses are difficult to definitely establish since ASC has a similar serologic profile as autoimmune hepatitis and liver histological analysis is frequently non-specific, whereas clinically amyopathic JDM diagnosis depends mostly on classical dermatological symptoms, while the rest of the diagnostic criteria, including the necessity for skin or muscle biopsy and the presence of myositis specific antibodies, are still not uniformed. In spite of these challenges, our patient clearly met European League Against Rheumatism/American College of Rheumatology classification criteria for CAJDM and The European Society for Pediatric Gastroenterology, Hepatology and Nutrition diagnostic criteria for ASC. Since elevated serum transaminases, the presence of serum antinuclear antibodies and hypergammaglobulinemia could be explained as a part of both JDM and ASC, the underlying pathophysiology remains debatable. Intriguingly, JDM and ASC share genetic predisposition including human leukocyte antigen allele DRB1*0301 and tumor necrosis factor α 308A allele. Furthermore, both humoral and cellular components of the adaptive immune system contribute to the pathogenesis of JDM and ASC. Moreover, recent findings indicate that the loss of the CD28 expression on T-cells plays a significant role in their pathogenesis along with the Th17 immune pathway. Despite these common features that suggest shared autoimmunity, AILD and autoimmune myositis are traditionally studied and managed independently. The lack of therapies that target the underlying cause results in a high rate of adverse events due to unspecific immunosuppressive therapy. Shared autoimmunity is an ideal area to develop new, targeted immunotherapy that would hopefully be beneficial for more than one disease.

Anti-nuclear matrix protein 2+ juvenile dermatomyositis with severe skin ulcer and infection: A case report and literature review

BACKGROUND

Juvenile dermatomyositis (JDM) is an idiopathic inflammatory myopathy that occurs in childhood. It is characterized by muscle weakness and a characteristic rash. Previous literature reports have rarely described JDM with severe skin ulcers and infections.

CASE SUMMARY

Herein, we describe a case of a 2-year-old female patient who suffered from JDM, whose myositis-specific autoantibodies were positive for anti-nuclear matrix protein 2 antibody, with progressively worsening skin ulcers and severe infections. The patient was treated with glucocorticoids and various immunosuppressants. Nevertheless, further progression of the disease and the combination of primary disease and severe infection in the later period were fatal.

CONCLUSION

In children, anti-nuclear matrix protein 2+ JDM combined with skin ulcers often indicates severe disease. In such cases, personalized treatment for the primary disease and infection prevention and control are essential.

Juvenile Dermatomyositis

Die juvenile Dermatomyositis (JDM) ist die häufigste chronische entzündliche Myopathie des Kindesalters. In dieser Übersicht soll der aktuelle Kenntnisstand hinsichtlich der Diagnostik, Behandlung und Überwachung der JDM dargestellt werden. So liegen häufig myositis-spezifische Antikörper vor, die mit klinischen Phänotypen und dem Verlauf der Erkrankung korrelieren. Typ I Interferone spielen eine wichtige Rolle in der Pathogenese der Erkrankung. Möglicherweise kann diese Beobachtung in der Zukunft zu gezielten Therapien führen. Da langfristig schwerwiegende Komplikationen, wie z. B. Kalzinosen oder Lipodystrophie, drohen, besonders bei auf Dauer unzureichend kontrollierter Erkrankung, ist eine möglichst rasche und effektive Behandlung anzustreben. Zu diesem Zweck sollte eine intensive Remissionsinduktionstherapie, gefolgt von einer zielgerichteten Therapie angestrebt werden. Verschiedene validierte Messinstrumente stehen zur Verfügung, um den Verlauf der Erkrankung zu beurteilen. Die Pro-KIND-Initiative der Gesellschaft für Kinder- und Jugendrheumatologie hat Praxis- und Konsens-basiert in Deutschland sowohl eine diagnostische als auch eine Treat-to-Target-Behandlungsstrategie entwickelt. Im Rahmen nationaler und internationaler Kollaborationen soll sich die Behandlung der JDM in der Zukunft weiter verbessern.

Development of Graves' disease during drug-free remission of juvenile dermatomyositis

We report a Japanese boy with Graves' disease (GD) which developed during drug-free remission of juvenile dermatomyositis (JDM). He had been diagnosed with JDM at the age of 6 years by typical skin rashes, muscle weakness, elevated serum transaminase levels, and typical findings of both magnetic resonance imaging and muscle biopsy. Although anti-melanoma differentiation antigen 5 autoantibody was positive, there was no complication of interstitial lung disease. He showed good response to methylprednisolone pulse therapy followed by oral prednisolone in combination with weekly methotrexate (MTX) and achieved drug-free remission after 3.5 years of treatment. Nevertheless, serum levels of soluble interleukin-2 receptor (sIL-2R) gradually elevated to 3185 U/ml despite no signs of relapse or malignancy. Hyperactivity and attention deficit was also noted. One year and 3 months after the cessation of MTX, he presented with abdominal pain, tachycardia, and apparent goitre. Laboratory tests showed elevated free triiodothyronine, undetectable thyroid stimulating hormone (TSH), and positive anti-TSH receptor antibodies. 99mTc scintigraphy showed high levels of thyroid uptake. He was diagnosed with GD and treated with 15 mg/day of thiamazole. Although transient drug eruption was observed, his thyroid functions are currently well-controlled on 5 mg/day of thiamazole. In conclusion, to our knowledge, this is the first report in English literature describing complication of GD with JDM. Unexpected elevation of sIL-2R could be a clue to the diagnosis of GD during the follow-up of JDM.

Clinical Characteristics of Juvenile Idiopathic Inflammatory Myopathy and Comparison With Adult Patients: Analysis From a Multicentric Cohort in Spain

METHODS

This study reviewed the medical records of patients from the REMICAM cohort, a multicentric longitudinal study carried out in patients with IIM, followed up between 1980 and 2014 in 12 hospitals in Madrid, Spain. Patients with definite or probable JPM, JDM, adult DM, and adult PM according to the modified Bohan and Peter criteria were selected. We compared the characteristics between JDM and JPM, and between JIIM and adult IIM.

RESULTS

Eighty-six juvenile patients (75 JDMs and 11 JPMs) and 283 adult patients (133 DMs and 150 PMs) were included. Compared with patients with JDM, patients with JPM were older at diagnosis, had more fever and arthritis, and were less frequently treated with disease-modifying antirheumatic drugs (these differences were not statistically significant). Compared with patients with adult DM, those with JDM presented more frequently with calcinosis (33.8% vs 6.9%, p < 0.0001) and had less severe infections (4.3% vs 23.4%, p < 0.0001), malignancies (1.3% vs 25.6%, p < 0.0001), and mortality (3.5% vs 33%, p < 0.0001). Patients with JDM were treated less frequently with azathioprine (10.8% vs 44.7%, p < 0.0001).

CONCLUSIONS

Our findings confirm that JIIMs are a heterogeneous group of diseases with relevant differences compared with adult IIMs.

Morphological Characteristics of Idiopathic Inflammatory Myopathies in Juvenile Patients

Background: In juvenile idiopathic inflammatory myopathies (IIMs), morphological characteristic features of distinct subgroups are not well defined. New treatment strategies require a precise diagnosis of the subgroups in IIM, and, therefore, knowledge about the pathomorphology of juvenile IIMs is warranted. Methods: Muscle biopsies from 15 patients (median age 8 (range 3–17) years, 73% female) with IIM and seven controls were analyzed by standard methods, immunohistochemistry, and transmission electron microscopy (TEM). Detailed clinical and laboratory data were accessed retrospectively. Results: Proximal muscle weakness and skin symptoms were the main clinical symptoms. Dermatomyositis (DM) was diagnosed in 9/15, antisynthetase syndrome (ASyS) in 4/15, and overlap myositis (OM) in 2/15. Analysis of skeletal muscle tissues showed inflammatory cells and diffuse upregulation of MHC class I in all subtypes. Morphological key findings were COX-deficient fibers as a striking pathology in DM and perimysial alkaline phosphatase positivity in anti-Jo-1-ASyS. Vascular staining of the type 1 IFN-surrogate marker, MxA, correlated with endothelial tubuloreticular inclusions in both groups. None of these specific morphological findings were present in anti-PL7-ASyS or OM patients. Conclusions: Morphological characteristics discriminate IIM subtypes in juvenile patients, emphasizing differences in aetiopathogenesis and supporting the notion of individual and targeted therapeutic strategies.

Autoantibody Profile of Children with Juvenile Dermatomyositis

OBJECTIVE

To study autoantibody profile in juvenile dermatomyositis (JDM) and to look for phenotypic associations of these autoantibodies, if any.

METHODS

Thirty-four children with JDM with a minimum follow-up duration of 24 mo were enrolled. Clinical findings and investigations at the time of diagnosis were noted from the clinic records. At inclusion, they were clinically evaluated for residual disease, disease activity and complications. All the enrolled patients were tested for antinuclear antibodies (ANA), muscle specific antibodies (MSA) and myositis associated autoantibodies (MAA).

RESULTS

ANA positivity was seen in 14/34 children. At least one MSA or MAA was present in 8/34 children. Anti-SRP, anti-MDA-5, and anti-Mi-2 antibodies were present in 4, 3, and 1 patient, respectively. Anti-SSA/Ro52 antibody was positive in 1 child. All four children with anti-SRP antibody were girls, who had polycyclic course. Two of them developed calcinosis. Prominent skin involvement with less severe muscle involvement and monocyclic course were seen in patients with anti-MDA-5 antibody. Two of them had arthritis/arthralgia at initial presentation. The only patient with anti-Mi-2 had normal muscle strength at enrollment. None of the patients had anti-synthetase antibodies (anti-Jo-1, anti-PL-7, anti-PL-12, anti-EJ), anti-Ku, anti-Scl-70, anti-NXP-2 or anti-HMG CoA.

CONCLUSION

Eight patients tested positive for at least one MSA or MAA. The prevalence of autoantibodies was low. Positivity for anti-SRP, anti-MDA-5, anti-Mi-2 and anti-SSA/Ro52 antibodies was seen in 4, 3, 1 and 1 patients, respectively. Ethnic differences and testing for autoantibodies during/after therapy could be responsible for the low positivity rate for autoantibodies.

Updates on interferon in juvenile dermatomyositis: pathogenesis and therapy

PURPOSE OF REVIEW

This review provides updates regarding the role of interferon (IFN) in juvenile dermatomyositis (JDM), including comparison to interferonopathies and therapeutic implications.

RECENT FINDINGS

Transcriptomic and protein-based studies in different tissues and peripheral IFN-α assessment have demonstrated the importance of the dysregulated IFN pathway in JDM. Additional studies have validated IFN-regulated gene and protein expression correlation with disease activity in blood and muscle, with potential to predict flares. Type I and II IFN both are dysregulated in peripheral blood and muscle, with more type I IFN in skin. Muscle studies connects hypoxia to IFN production and IFN to vascular dysfunction and muscle atrophy. JDM overlaps with interferonopathy phenotype and IFN signature. There are multiple case reports and case series noting decreased IFN markers and clinical improvement in refractory JDM with Janus kinase (JAK) inhibitors.

SUMMARY

Studies confirm IFN, particularly type I and II IFN, is an important part of JDM pathogenesis by the level of dysregulation and correlation with disease activity, as well as IFN recapitulating key JDM muscle pathology. Smaller studies indicate there may be differences by myositis-specific autoantibody group, but validation is needed. JAK inhibitors are a promising therapy as they can inhibit IFN signaling, but further study is needed regarding which patients will benefit, dosing, and safety monitoring.

Favorable outcomes with reduced steroid use in juvenile dermatomyositis

BACKGROUND

High-intensity glucocorticoid regimens are commonly used to induce and maintain remission in Juvenile Dermatomyositis but are associated with several adverse side-effects. Evidence-based treatment guidelines from North American and European pediatric rheumatology research societies both advocate induction with intravenous pulse steroids followed by high dose oral steroids (2 mg/kg/day), which are then tapered. This study reports the time to disease control with reduced glucocorticoid dosing.

METHODS

We retrospectively reviewed the records at a single tertiary-care children's hospital of patients diagnosed with Juvenile Dermatomyositis between 2000 and 2014 who had a minimum of 2 years of follow-up. The primary outcome measure was time to control of muscle and skin disease. Additional outcome measures included glucocorticoid dosing, effect of treatment on height, frequency of calcinosis, and complications from treatment.

RESULTS

Of the 69 patients followed during the study period, 31 fulfilled inclusion criteria. Median length of follow-up was 4.58 years, (IQR 3-7.5). Myositis control was achieved in a median of 7.1 months (IQR 0.9-63.4). Cutaneous disease control was achieved in a median of 16.7 months (IQR 4.3-89.5). The median starting dose of glucocorticoids was 0.85 mg/kg/day, (IQR 0.5-1.74). The median duration of steroid treatment was 9.1 months, (IQR 4.7-17.4), while the median duration of any pharmacotherapy was 29.2 months (IQR 10.4 to 121.3). Sustained disease control off medications was achieved in 21/31 (68%) patients by the end of review. Persistent calcinosis was identified in only one patient (3%).

CONCLUSION

Current accepted treatment paradigms for Juvenile Dermatomyositis include oral glucocorticoids beginning at 2 mg/kg/day and reduced over a prolonged time period. However, our results suggest that treatment using reduced doses and duration with early use of steroid-sparing agents is comparably effective in achieving favorable outcomes in Juvenile Dermatomyositis.

Severe onset of inflammatory myositis in a child: think to paraneoplastic myositis

Background

Juvenile idiopathic inflammatory myopathies (JIIMs) are a group of heterogenous, acquired, autoimmune disorders that affect the muscle. While the association between IIMs and malignancy has been widely reported in adults, cancer-associated myositis (CAM) is rare in children, so that routine malignancy screening is not generally performed. This report shows a case of severe CAM in a child.

Case presentation

An 11-years-old girl presented with worsening dyspnea after a 3-weeks history of progressive proximal weakness, myalgia, dysphagia, and weight loss. Her past history was remarkable for a type I Arnold-Chiari malformation associated with an anterior sacral meningocele. Physical examination showed severe hypotony and hypotrophy. Pulse oximetry and blood test showed a type II respiratory failure (SpO₂ 88%, pCO₂ 68 mmHg) and increased muscle enzyme levels (CPK 8479 U/L, AST 715 U/L, ALT 383 U/L, LDH 1795 U/L). The patient needed invasive mechanical ventilation. Inflammatory myositis was considered and treatment with intravenous methylprednisolone (30 mg/Kg/day for 3 days followed by 2 mg/Kg/day) and IVIG (1 g/kg/day for 2 days) was started. Muscle biopsy showed endomysial and perimysial necrosis and inflammation. The presence of serum anti-TIF1-γ antibody positivity led to a malignancy screening. Whole-body MRI showed a mature teratoma underneath sacral meningocele and both lesions were surgically removed.

Given the histological and clinical severity of the myopathy, mycophenolate (500 mg twice a day) and rituximab (360 mg/m², 4 weekly infusions) were added. Due to extreme muscular wasting, severe malnutrition and intolerance to enteral feeding the patient needed a transient tracheostomy and parenteral nutrition, followed by physiotherapy, speech therapy and nocturnal non-invasive ventilation. A complete remission was achieved 3 months after.

Conclusions

Among cancer-associated autoantibodies (CAAs) in adult patients, anti-TIF1-γ carries the highest risk of CAM, which recognizes with a high likelihood a paraneoplastic pathogenesis. In children, anti-TIF1-γ antibody has been associated with severe cutaneous disease, lipodystrophy, and chronic disease course, but not with CAM, which is overall rare in younger patients. Severe onset of a JIIM, especially if anti-TIF1-γ antibody positive, should prompt suspect of a CAM and lead to a screening for malignancy.

Metabolomics Analysis Identifies a Lipidomic Profile in Treatment Naïve Juvenile Dermatomyositis Patients versus Healthy Control Subjects

Objectives

To perform an exploratory study to identify a JDM serum metabolic profile that differs from healthy controls (HCs) and responds to immunosuppressive treatment.

Methods

Blood was collected from 9 HCs and 10 patients diagnosed with probable (n = 4) or definite (n = 6) JDM based on the criteria of Bohan and Peter for myositis, with 7 of the 10 providing longitudinal samples following initiation of treatment; these patients comprised the treatment-naïve cohort. Sera underwent mass spectroscopy–based measurements of targeted metabolic intermediates, including 15 amino acids, 45 acylcarnitines (ACs), 15 ceramides and 29 sphingomyelins. Principal components analysis reduced metabolites into smaller sets of factors each comprised of correlated metabolic intermediates. Factor scores and metabolite concentrations were compared with HCs using two-sample t-tests while treatment effects were evaluated using paired t-tests.

Results

Of eight principal components analysis–derived metabolite factors (one AC, two amino acids, three sphingosine and two ceramide), two were significantly associated with JDM: one AC factor containing mostly long-chain ACs (P = 0.049) and one ceramide factor (P < 0.01). For 12 individual ACs, mostly long chain, and three ceramides, concentrations were significantly greater for JDM than HCs. Factors based on these individual metabolites showed decreasing scores with treatment (P = 0.03 and P < 0.01, respectively).

Conclusion

While additional validation is needed, these lipids have potential as JDM serum diagnostic and/or treatment biomarkers. Additionally, the significant association of long-chain ACs and ceramides with JDM offers insights regarding pathogenesis, implicating dysregulation of mitochondrial fatty acid β-oxidation.

Myositis autoantibodies in a racially diverse population of children with idiopathic inflammatory myopathies

BACKGROUND

Juvenile idiopathic inflammatory myopathies (JIIMs) is a group of autoimmune disorders, including juvenile dermatomyositis (JDM), juvenile polymyositis (JPM) and overlap myositis, that are characterized by proximal muscle weakness, elevated levels of serum muscle enzymes, and pathognomonic skin findings. While the exact etiology of JIIMs is unclear, the presence of myositis specific autoantibodies (MSAs) have been associated with certain clinical phenotypes, organ involvement and disease prognosis. To date, there have been few studies of the associations between MSA presence and patient ethnicity. It is important to understand the extent to which ethnicity impacts disease manifestations, organ involvement and clinical outcomes. The goal of our study is to determine MSA and myositis associated autoantibody (MAA) presence, clinical phenotype, and disease course in a racially diverse population of pediatric patients with JIIMs.

METHODS

Patients age 2-21 years with a prior diagnosis of JDM, JPM or overlap myositis, who had been tested for MSA/MAA, were eligible for study inclusion. Clinical and laboratory data were collected retrospectively via manual chart review in this single-center study. Descriptive statistics were performed to summarize each variable. Given the small sample size, non-parametric testing was performed using Fischer's exact test, Wilcoxon rank sum test and Kruskal-Wallis test.

RESULTS

Thirty one patients were included in the analysis. Race and ethnicity were self-reported as Hispanic (48.4%), white (25.8%), and Black (25.8%). The most prevalent MSAs were anti-MDA5 (25.8%), anti-p155/140 (22.6%) and anti-MJ (19.4%). Presence of autoantibodies (p = 0.04) and pulmonary disease (p = 0.03) were significantly higher in patients of Black or Hispanic descent compared with white descent. Anti-MDA5 antibodies, cutaneous ulceration, cardiopulmonary involvement, hospitalizations and one death were only reported in patients with Black or Hispanic descent. Patients with anti-MDA5 antibodies were more likely to be male (p = 0.04) and to have cutaneous ulceration (p = 0.02).

CONCLUSIONS

This study describes the prevalence of MSA/MAA in a racially diverse group of patients with JIIM and further delineates clinical phenotype and disease complications in these groups. We found a relatively high proportion of children with anti-MDA5 antibodies and described potentially worse clinical courses in children of Black or Hispanic descent. Further investigation is warranted to examine these findings.

The Diagnostic Value of MR IVIM and T2 Mapping in Differentiating Autoimmune Myositis From Muscular Dystrophy

RATIONALE AND OBJECTIVES

To confirm the feasibility and compare the accuracy of magnetic resonance imaging intravoxel incoherent motion (IVIM) and T2 mapping models for the differentiation of autoimmune myositis from muscular dystrophy.

MATERIALS AND METHODS

Fourty-two autoimmune myositis and 11 muscular dystrophy patients proven by diagnostic criteria were enrolled in the study. Conventional MR sequences, IVIM, and T2 mapping through the bilateral thighs were obtained as well as blood samples for all patients. IVIM and T2 mapping parameters as well as serum markers were compared between the autoimmune myositis and muscular dystrophy groups. Mann-Whitney U tests were performed for statistical analysis along with receiver operating characteristic curves. Spearman correlation coefficient models were constructed to analyze the correlation between IVIM and T2 mapping with serological parameters.

RESULTS

The intramuscular apparent diffusion coefficient, tissue diffusivity (D), perfusion fraction (f_p), and T2 relaxation time values were statistically significantly different between the autoimmune myositis and muscular dystrophy groups (p < 0.05). Pseudo diffusivity (D_p) values showed no statistical difference between the groups (p > 0.05). D parameter of IVIM sequences differentiated autoimmune and muscular dystrophy with a higher specificity of 75.60%. T2 values within the thighs were correlated with serum creatine kinase and lactate dehydrogenase levels (p < 0.05).

CONCLUSION

Thigh muscle IVIM and T2 mapping parameters are useful in differentiating autoimmune myositis from muscular dystrophy, particularly the IVIM parameters.

From Diagnosis to Prognosis: Revisiting the Meaning of Muscle ISG15 Overexpression in Juvenile Inflammatory Myopathies

OBJECTIVE

Juvenile idiopathic inflammatory/immune myopathies (IIMs) constitute a highly heterogeneous group of disorders with diagnostic difficulties and prognostic uncertainties. Circulating myositis-specific autoantibodies (MSAs) have been recognized as reliable tools for patient substratification. Considering the key role of type I interferon (IFN) up-regulation in juvenile IIM, we undertook the present study to investigate whether IFN-induced 15-kd protein (ISG-15) could be a reliable biomarker for stratification and diagnosis and to better elucidate its role in juvenile IIM pathophysiology.

METHODS

The study included 56 patients: 24 with juvenile dermatomyositis (DM), 12 with juvenile overlap myositis (OM), 10 with Duchenne muscular dystrophy, and 10 with congenital myopathies. Muscle biopsy samples were assessed by immunohistochemistry, immunoblotting, and real-time quantitative polymerase chain reaction. Negative regulators of type I IFN (ISG15 and USP18) and positive regulators of type I IFN (DDX58 and IFIH1) were analyzed.

RESULTS

ISG15 expression discriminated patients with juvenile IIM from those with nonimmune myopathies and, among patients with juvenile IIM, discriminated those with DM from those with OM. Among patients with juvenile DM, up-regulation of the type I IFN positive regulators DDX58 and IFIH1 was similar regardless of MSA status. In contrast, the highest levels of the type I IFN negative regulator ISG15 were observed in patients who were positive for melanoma differentiation-associated gene 5 (MDA-5). Finally, ISG15 levels were inversely correlated with the severity of muscle histologic abnormalities and positively correlated with motor performance as evaluated by the Childhood Myositis Assessment Scale and by manual muscle strength testing.

CONCLUSION

Muscle ISG15 expression is strongly associated with juvenile DM, with patients exhibiting a different ISG-15 muscle signature according to their MSA class. Patients with juvenile DM who are positive for MDA-5 have higher expression of ISG15 in both gene form and protein form compared to the other subgroups. Moreover, our data show that negative regulation of type I IFN correlates with milder muscle involvement.

Corticosteroid discontinuation, complete clinical response and remission in juvenile dermatomyositis

OBJECTIVE

A North American registry of JDM patients was examined for frequency of and factors associated with corticosteroid discontinuation, complete clinical response and remission.

METHODS

We evaluated probability of achieving final corticosteroid discontinuation, complete clinical response and remission in 307 JDM patients by Weibull time-to-event modelling; conditional probability of complete clinical response and remission using Bayesian network modelling; and significant predictors with multivariable Markov chain Monte-Carlo Weibull extension models.

RESULTS

The probability of corticosteroid discontinuation was 56%, complete clinical response 38% and remission 30% by 60 months after initial treatment in 105 patients. The probability of remission was conditional on corticosteroid discontinuation and complete clinical response. Photosensitivity, contractures and a longer time to complete clinical response were predictive of the time to final corticosteroid discontinuation. Anti-MJ (NXP2) autoantibodies and a Northwest residential geoclimatic zone were predictive of shorter time to complete clinical response, while dysphonia, contractures, an increase in medications within 24 months and a longer time to corticosteroid discontinuation were associated with longer time to complete clinical response. Anti-p155/140 (TIF1) autoantibodies, an increase in medications within 12-24 months, or longer times to corticosteroid discontinuation and complete clinical response were associated with longer time to remission.

CONCLUSION

JDM patients achieve favourable outcomes, including corticosteroid discontinuation, complete clinical response and remission, although timelines for these may be several years based on time-dependent analyses. These outcomes are inter-related and strong predictors of each other. Selected clinical features and myositis autoantibodies are additionally associated with these outcomes.

External validation of the EULAR/ACR idiopathic inflammatory myopathies classification criteria with a Japanese paediatric cohort

OBJECTIVES

To assess the performance of the EULAR/ACR idiopathic inflammatory myopathies (IIMs) classification criteria to classify juvenile IIMs (JIIMs) in an Asian paediatric population.

METHODS

Sixty-eight JIIM patients and 49 non-JIIM patients diagnosed at seven major paediatric rheumatology centres in Japan between 2008 and 2015 were enrolled. Retrospective data were collected, and each patient's data form was submitted. The expert group reviewed the forms and re-examined the diagnoses. The EULAR/ACR criteria were then applied and the probability of having JIIM was determined for each case. The sensitivity and specificity of the EULAR/ACR criteria were compared with those of other existing criteria.

RESULTS

The sensitivity/specificity of the EULAR/ACR classification criteria were 92.1/100% with muscle biopsy data (n = 38); 86.7/100% without muscle biopsy data (n = 30) and 89.7/100% in our total cohort (n = 68). The sensitivity of Bohan and Peter's criteria and Tanimoto's criteria were 80.9 and 64.7% in our total cohort, respectively. Among 68 physician-diagnosed JIIM patients, seven cases (three JDM and four overlap myositis) were not classified as JIIM because the probability did not reach the cut-off point (55%). The three JDM patients all presented with only one of the three skin manifestations that are listed in the criteria: Gottron's sign.

CONCLUSION

Our validation study with Japanese JIIM cases indicates that the EULAR/ACR classification criteria for IIM generally perform better than existing diagnostic criteria for myositis.

Investigating genetic drivers of juvenile dermatomyositis pathogenesis using bioinformatics methods

Juvenile dermatomyositis (JDM) is a chronic autoimmune disease. The pathogenic mechanisms remain ill-defined. The purpose of this study was to identify key genes related to JDM. Microarray datasets were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEG) were identified. Then, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, and protein-protein interaction (PPI) network were carried out. In addition, the hub genes were selected by cytoHubba. The expression profile and diagnostic capacity (receiver-operator curve [ROC]) of interested hub genes were verified. Gene set enrichment analysis (GSEA) was also carried out. Moreover, the signature of hub genes was then used as a search query to explore the Connectivity Map (CMAP). A total of 128 DEG were identified. The enriched functions and pathways of the DEG include response to virus, negative regulation of cell migration, cadmium ion transmembrane transport, defense response to Gram-negative bacterium, positive regulation of megakaryocyte differentiation, and negative regulation of angiogenesis. Twenty-one hub genes were identified. The expression levels of the interested genes were also confirmed. ROC analysis confirmed that the expression of these genes can distinguish JDM from controls. GSEA showed that these genes are mainly related to "inflammatory response", "complement", "interferon-α response", "IL6/JAK/STAT3 signaling", "TGF-β signaling", "IL2/STAT5 signaling" and "TNF-α signaling via NF-κB". The CMAP research found some compounds with the potential to counteract the effects of the dysregulated molecular signature in JDM. In this study, bioinformatics methods were used to identify DEG, which helps us understand the molecular mechanisms of JDM and provide candidate targets for diagnosis and treatment of JDM.

Clinical Features and Cutaneous Manifestations of Juvenile and Adult Patients of Dermatomyositis Associated with Myositis-Specific Autoantibodies

Dermatomyositis is one of the idiopathic inflammatory myopathies, which is characterized with specific skin manifestations, and considered as an autoimmune disease. Dermatomyositis is a heterogeneous disorder with various presences, severities and characteristics of myositis, dermatitis, and interstitial lung disease. Our and others' data showed that myositis-specific autoantibodies have been associated with distinct clinical features. This article reviewed the epidemiology and characteristic clinical features of the different types of antibody-associated dermatomyositis in adult and juvenile patients, which include the severity of myopathy, the potential complication of interstitial lung disease, potential association with malignancies, and characteristic cutaneous manifestations.

Prevalence of Epstein-Barr virus infection and characteristics of lymphocyte subsets in newly onset juvenile dermatomyositis

BACKGROUND

The underlying etiology of juvenile dermatomyositis (JDM) is unknown. T cell deficiency as well as Epstein-Barr virus (EBV) infection had been suspected to be involved in the pathogenesis, but it has been poorly evaluated in JDM patients.

METHODS

This study described the traits of T and B lymphocyte subsets in newly onset JDM patients and the incidence of EBV infection in JDM patients compared with match controls. Newly developed JDM patients from 2014 to 2018 were included in the study. Lymphocytes with different markers (CD3⁺, CD3⁺CD4⁺, CD3⁺CD8⁺, CD3^-CD19⁺ and CD3^-CD16⁺CD56⁺) were tested with flow cytometry in the first admission or after 6 months of treatment. Statistical analysis was conducted to compare the EBV infection in the group of JDM patients and controls.

RESULTS

We observed that JDM patients had higher positive rate of Epstein-Barr nuclear antigen-immunoglobulin G (IgG) (P < 0.0001) as well as EBV capsid antigen-IgG (P < 0.05) than normal controls. CD3^-CD16⁺CD56⁺ lymphocyte was found to be extremely low in early stage of JDM patients, but increased after 6 months of treatment (P = 0.0091).

CONCLUSIONS

The level of CD3^-CD16⁺CD56⁺ cells may associate with the clinical course of JDM. EBV may act as an environmental factor predisposing patients to the development of JDM.

Anti-SAE autoantibody-positive Japanese patient with juvenile dermatomyositis complicated with interstitial lung disease - a case report

BACKGROUND

Clinical phenotypes and outcomes in juvenile dermatomyositis (JDM) have been defined by various myositis-specific autoantibodies (MSAs). One of the recently described MSAs associated with DM is targeted against the small ubiquitin-like modifier 1 activating enzyme (SAE). We report an anti-SAE autoantibody-positive JDM patient complicated with interstitial lung disease (ILD).

CASE PRESENTATION

An 8-year-8-month-old Japanese girl presented with bilateral eyelid edema and facial erythema. At 8 years 4 months, she had dry cough and papules with erythema on the dorsal side of the interphalangeal joints of both hands. Her facial erythema gradually worsened and did not improve with topical steroids. At the first visit to our department at 8 years 8 months of age, she had a typical heliotrope rash and Gottron's papules, with no fever or weight loss, and a chest computed tomography scan showed ground-glass opacity under visceral pleura. There was no clinical evidence of myositis, muscle weakness, myalgia, or muscle magnetic resonance imaging (MRI) findings. She had mild dry cough, without any signs of respiratory distress. Laboratory tests showed no elevated inflammatory markers. She had a normal serum creatine kinase level with a slightly elevated aldolase level, and serum anti-SAE autoantibody was detected by immunoprecipitation-western blotting. She was diagnosed with juvenile amyopathic DM complicated by ILD and received two courses of methylprednisolone pulse therapy followed by oral corticosteroid and cyclosporin A. We gradually reduced the corticosteroid dose as her skin rash improved after treatment initiation. There was no progression of muscle symptoms, dysphagia, or disease flare during a 24-month follow-up period.

CONCLUSIONS

We report a patient with anti-SAE autoantibody-positive JDM complicated by interstitial pneumonia. This patient had no progression of muscle symptoms and dysphagia during a 24-month follow-up period, which differs from previous reports in adult patients with MSAs. There have been no previous reports of pediatric patients with SAE presenting with ILD. However, ILD seen in this case was not rapidly progressive and did not require cytotoxic agents. To prevent overtreatment, appropriate treatment choices are required considering the type of ILD.

Clinical characteristics and management of clinically amyopathic juvenile dermatomyositis across four academic centers

BACKGROUND/OBJECTIVES

Clinically amyopathic juvenile dermatomyositis (CAJDM) is an uncommon but important subset of patients with juvenile dermatomyositis, characterized by pathognomonic cutaneous findings without clinically evident muscle weakness. With limited data available and lack of standardized management guidelines for CAJDM, we sought to describe common features, including early indicators that may be associated with progression of muscle disease, and review the course and treatment of these patients.

METHODS

A retrospective chart review of patients with CAJDM was conducted at four North American academic centers between the years 2000 and 2015.

RESULTS

Twenty-nine patients were included, of whom 21 (72%) were female. After a median follow-up of 4 years (IQR 1.8-5.8 years), 5 of the 29 (17%) patients with CAJDM evolved into classic juvenile dermatomyositis. Median time to develop weakness was 12 months (IQR 8-19 months) after diagnosis. The skin disease of CAJDM patients who did not develop weakness was often found to be recalcitrant with 58% of them requiring multiple systemic therapies to control their cutaneous disease.

CONCLUSION

These results highlight the need for long-term monitoring for the development of myositis in CAJDM and for prospective studies on treatment of recalcitrant skin disease.

Anti-MDA5 juvenile idiopathic inflammatory myopathy: a specific subgroup defined by differentially enhanced interferon-α signalling

OBJECTIVES

JDM and juvenile overlap myositis represent heterogeneous subtypes of juvenile idiopathic inflammatory myopathy (JIIM). Chronic evolution can occur in up to 60% of cases, and morbidity/mortality is substantial. We aimed to describe the clinical, biological, histological and type I IFN status in JIIM associated with anti-melanoma differentiation-associated protein 5 (anti-MDA5) autoantibodies at presentation (group 1) in comparison with other JIIM (group 2).

METHODS

This was a retrospective and prospective study of patients with JIIM ascertained from three French paediatric rheumatology reference centres between 2013 and 2019. Muscle biopsies were reviewed. Type I interferon pathway activity was assessed by dosage of IFNα serum protein and the expression of IFN-stimulated genes.

RESULTS

Sixty-four patients were included, 13 in group 1 (54% JDM and 46% juvenile overlap myositis) and 51 in group 2 (76% JDM and 24% juvenile overlap myositis). Group 1 patients demonstrated more arthritis, skin ulcerations, lupus features and interstitial lung disease, and a milder muscular involvement. Serum IFNα levels were higher in group 1 than 2, and decreased after treatment or improvement in both groups. Outcome was similar in both groups. Unconventional treatment (more than two lines) was required in order to achieve remission, especially when skin ulceration was reported.

CONCLUSION

This study indicates a higher frequency of arthritis, skin ulcerations and interstitial lung disease, but milder muscular involvement, in JIIM with positive anti-MDA5 autoantibodies compared with other JIIM. Our data support an important role of systemic IFNα in disease pathology, particularly in the anti-MDA5 auto-antibody-positive subgroup. In severe and refractory forms of JIIM, IFNα may represent a therapeutic target.

Serum protein biomarkers for juvenile dermatomyositis: a pilot study

BACKGROUND

Blood accessible biomarkers to assess disease activity and their response to therapies in Juvenile Dermatomyositis (JDM) are urgently needed. This pilot study aims to identify serum protein biomarkers associated with clinical disease activity in untreated JDM and their response to medical therapy.

METHODS

SomaScan® technology screened JDM patients for 1305 proteins at three points: 1) before start of treatment, 2) while on therapy, and 3) after treatment tapering when patients were clinically inactive. To define disease associated biomarkers, SomaScan® data from untreated JDM patients (n = 8) were compared to SomaScan® data from an independent age-matched healthy control group (n = 12). Longitudinal analysis defined treatment responsive proteins at three time points: untreated (7 samples), treated (7 samples), and clinically inactive (6 samples). To confirm the SomaScan® data, a subset of nine candidate proteins (CXCL11, IL-17B, IL-17D, IL-22, CXCL10, MCP-1, ANGPT2, MIF, IL-23) were tested by ELISA after adding 2 JDM (one untreated, one clinically inactive) serum samples to the same group of JDM girls (8 untreated, 7 treated; 7 clinically inactive) as well as with 17 age, gender, matched healthy controls.

RESULTS

Comparison of untreated JDM versus healthy controls identified 202 elevated and 49 decreased serum proteins in JDM patients with an adjusted p-value < 0.001. Only 82 out of 251 identified biomarker candidates responded to treatment while 12 out of these 82 proteins returned to their original untreated disease levels upon therapy tapering. The ELISA testing of the untreated samples for nine candidate proteins confirmed previously known biomarkers (CXCL10 or IP-10, CXCL11 or I-TAC and MCP-1) and identified novel biomarkers including IL-22, Angiopoetin-2, and IL-17B in a cross-sectional analysis comparing 8 untreated JDM and 17 age/gender matched controls. The subsequent longitudinal data by ELISA were not concordant for some biomarkers (IL-22 and IL-17B), but the other biomarkers either normalized or rebounded concordantly.

CONCLUSIONS

Blood accessible protein biomarkers reflecting JDM pathophysiology were identified; some of them rebounded after therapy was tapered. Further studies bridging these biomarkers to specific clinical features of JDM are required to confirm the clinical utility of these serum protein biomarkers.

Distinct tissue injury patterns in juvenile dermatomyositis auto-antibody subgroups

INTRODUCTION

Juvenile dermatomyositis (JDM) can be classified into clinical serological subgroups by distinct myositis-specific antibodies (MSAs). It is incompletely understood whether different MSAs are associated with distinct pathological characteristics, clinical disease activities, or response to treatment.

METHODS

We retrospectively reviewed clinicopathological data from consecutive JDM patients followed in the pediatric rheumatology clinic at a single center between October 2016 and November 2018. Demographics, clinical data, and laboratory data were collected and analyzed. Detailed muscle biopsy evaluation of four domains (inflammation, myofiber, vessels, and connective tissue) was performed, followed by statistical analysis.

RESULTS

Of 43 subjects included in the study, 26 (60.5%) had a detectable MSA. The most common MSAs were anti-NXP-2 (13, 30.2%), anti-Mi-2 (7, 16.3%), and anti-MDA-5 (5, 11.6%). High titer anti-Mi-2 positively correlated with serum CK > 10,000 at initial visit (r = 0.96, p = 0.002). Muscle biopsied from subjects with high titer anti-Mi-2 had prominent perifascicular myofiber necrosis and perimysial connective tissue damage that resembled perifascicular necrotizing myopathy, but very little capillary C5b-9 deposition. Conversely, there was no positive correlation between the levels of the anti-NXP-2 titer and serum CK (r = - 0.21, p = 0.49). Muscle biopsies from patients with anti-NXP-2 showed prominent capillary C5b-9 deposition; but limited myofiber necrosis. Only one patient had anti-TIF1γ autoantibody, whose muscle pathology was similar as those with anti-NXP2. All patients with anti-MDA-5 had normal CK and near normal muscle histology.

CONCLUSIONS

Muscle biopsy from JDM patients had MSA specific tissue injury patterns. These findings may help improve muscle biopsy diagnosis accuracy and inform personalized treatment of JDM.

The association between myositis-specific autoantibodies and muscle pathologies in idiopathic inflammatory myopathies

OBJECTIVE

To investigate specific muscle pathologies of different kinds of myositis-specific autoantibodies (MSAs) in idiopathic inflammatory myopathy (IIM) patients.

METHODS

One hundred eleven Chinese patients from Xiangya Hospital, Central South University diagnosed with IIMs according to European Neuromuscular Centre (ENMC) criteria were included. Clinical manifestation, myositis-specific autoantibodies, and histologic findings were evaluated to explore the pattern of necrosis, regeneration, and perifascicular atrophy, inflammatory cells in IIM patients with different MSAs.

RESULTS

Anti-SRP group has the lowest muscle strength scores, the highest creatine kinase levels, the most severe degree of necrosis and regeneration (1.90[0.80-3.95], 1.00[0.30-1.71]), and the lowest positive rate of MHC-I staining (35.71%). The anti-MDA5 group demonstrates the mildest pathological changes, with the fewest necrotic and regenerated muscle fibers (0.00[0.00-0.50], 0.00[0.00-0.00]), and the fewest inflammatory cell infiltration, and the highest muscle strength scores. The anti-NXP2 group has the most frequent inflammatory infiltrates, especially CD4+ T cells (31.14[15.00-39.00]). The patients with anti-NXP2 and the anti-TIF1γ antibodies show higher frequency of punched-out fibers (1.50[0.00-3.70], 0.00[0.00-1.00]) and perifascicular atrophy (71.43%, 55.56%). As for anti-synthetase antibodies (ASAs), the anti-Jo-1 group shows the most frequent rate of perifascicular necrosis (60%), while other ASA groups do not show perifascicular necrosis.

CONCLUSIONS

Of the MSAs, the anti-SRP antibody leads to the most severe muscle involvement, while the anti-MAD5 antibody the mildest. The anti-NXP2 and anti-TIF1γ groups have the most typical "DM" pathology. Key Points • Anti-SRP group shows severe muscle pathology while anti-MDA5 group shows the mildest. • Anti-NXP2 group has the most frequent inflammatory infiltrates. Pouch-out fibers and perifascicular atrophy are more prevalent in anti-NXP2 and anti-TIF1γ groups. • Anti-Jo-1 group is often accompanied by perifascicular necrosis, while other anti-synthetase antibody groups are not.

Transcriptional intermediary factor 1 (TIF1) and anti-TIF1γ antibody-positive dermatomyositis

Recently, great advancements have been made towards understanding the mechanisms underlying dermatomyositis (DM). Many novel autoantibodies, such as anti-MDA5, anti-TIF1γ, anti-NXP2, and anti-SAE, have been reported to be involved in DM. DM is now classified based on these myositis-specific autoantibodies. Anti-TIF1γ antibodies are closely associated with juvenile DM and adult cancer-associated DM. Anti-TIF1γ antibody-positive DM tends to present severe cutaneous manifestations, mild myositis, and dysphagia. TIF1γ (also known as TRIM33) plays a role in transcriptional elongation, DNA repair, differentiation of cells, embryonic development, and mitosis. Moreover, TIF1γ has been shown to suppress various tumors via the TGF-β/Smad and the Wnt/β-Catenin signaling pathways. In this review, we explore the relationship between TIF1γ, cancer, and DM. We also discuss the pathogenesis of anti-TIF1γ antibody-positive DM.