Validation and clinical significance of the Childhood Myositis Assessment Scale for assessment of muscle function in the juvenile idiopathic inflammatory myopathies

Disease activity trajectories in juvenile dermatomyositis from childhood to adulthood

OBJECTIVES

To assess whether there are identifiable subgroups of disease activity trajectory in a population of JDM patients-followed throughout childhood and into adulthood-and determine factors that predict those trajectory groupings.

METHODS

This is a retrospective, longitudinal inception cohort of patients with idiopathic inflammatory myopathies, largely JDM. We sought to identify baseline factors that predict membership into different groups (latent classes) of disease activity trajectory.

RESULTS

A total of 172 patients (64% females), with median age at diagnosis of 7.7 years, were analysed. We studied 4725 visits (1471 patient-years). We identified three latent classes of longitudinal disease activity, as measured by the modified DAS (DASm), with distinct class trajectories predicted by DASm at baseline, and by the changes of DASm from either baseline to 3 months or baseline to 6 months (early response to therapy). In the analysis in which DASm at baseline and the changes of DASm from baseline to 6 months are included as predictors, Class 1 (10%) has persistently high disease activity, Class 2 (34%) is characterized by moderate disease activity and Class 3 (56%) is characterized by individuals with a high early disease activity but an apparently good response to treatment and long-term low disease activity.

CONCLUSION

High early disease activity, and treatment resistance in the first few months, predict a more chronic longitudinal course of JDM.

Severe Post-Viral Polymyositis after COVID-19 in Childhood: A Case Report and Literature Review

Polymyositis is a rarely reported complication of COVID-19 illness, especially in children. Molecular mimicry may be a cause of hyperactivated autoimmunity, leading to various clinical manifestations, including myopathies. Symptoms vary from mild muscle weakness to severe rhabdomyolysis. We review the literature on post-COVID myositis and report a case of severe polymyositis in a 7-year-old boy, following undefined viral infection 3 weeks before the onset of muscle pain. Patient's condition deteriorated from physical activity-associated pain in the lower limbs to severe muscle weakness leading to dysphagia and mechanical ventilation. As antibodies against SARS-CoV-2 were detected and other possible conditions causing myositis were excluded, the diagnosis of post-COVID polymyositis was considered as the most likely. The patient was treated with high doses of methylprednisolone and cyclophosphamide, resulting in improvement. Although COVID-19 is becoming a seasonal disease, the infection itself and post-viral disorders, such as polymyositis, are still of great interest and require better investigation to ensure appropriate management for each individual. Our experience suggests that aggressive immunosuppressive therapy might be a solution for severe post-COVID-related diseases. This literature review is provided in addition to the case report presented at the 29th European Paediatric Rheumatology Congress; the abstract is available online in the Proceedings of the 29th European Paediatric Rheumatology Congress.

Decreased Peripheral Blood Natural Killer Cell Count in Untreated Juvenile Dermatomyositis Is Associated with Muscle Weakness

Juvenile Dermatomyositis (JDM) is the most common inflammatory myopathy in pediatrics. This study evaluates the role of Natural Killer (NK) cells in Juvenile Dermatomyositis (JDM) pathophysiology. The study included 133 untreated JDM children with an NK cell count evaluation before treatment. NK cell subsets (CD56low/dim vs. CD 56bright) were examined in 9 untreated children. CD56 and perforin were evaluated in situ in six untreated JDM and three orthopedic, pediatric controls. 56% of treatment-naive JDM had reduced circulating NK cell counts, designated "low NK cell". This low NK group had more active muscle disease compared to the normal NK cell group. The percentage of circulating CD56low/dim NK cells was significantly lower in the NK low group than in controls (0.55% vs. 4.6% p < 0.001). Examination of the untreated JDM diagnostic muscle biopsy documented an increased infiltration of CD56 and perforin-positive cells (p = 0.023, p = 0.038, respectively). Treatment-naive JDM with reduced circulating NK cell counts exhibited more muscle weakness and higher levels of serum muscle enzymes. Muscle biopsies from treatment-naive JDM displayed increased NK cell infiltration, with increased CD56 and perforin-positive cells.

Cardiac evaluation of patients with juvenile dermatomyositis

BACKGROUND

The present study aims to evaluate possible cardiac involvement in juvenile dermatomyositis (JDM) patients by conventional methods and cardiac magnetic resonance imaging (MRI) along with a systematic review of the literature on cardiac features in JDM.

METHODS

The study group consisted of JDM patients who underwent cardiac MRI. We conducted a systematic review of the published literature involving JDM patients with cardiac involvement.

RESULTS

In the present study, although baseline cardiologic evaluations including electrocardiography and echocardiography were within normal limits, we showed late gadolinium enhancement on cardiac MRI in 3 of 11 JDM patients. In the literature review, we identified 25 articles related to cardiac involvement in JDM. However, none of them, except one case report, included cardiac MRI of JDM patients.

CONCLUSION

Cardiac abnormalities have been reported among the less frequent findings in patients with JDM. Cardiovascular complications during the long-term disease course are a leading cause of morbidity and mortality in these patients. Early detection of cardiac involvement by cardiac MRI in patients with JDM and aggressive treatment of them may improve the clinical course of these patients.

IMPACT

The myocardium in patients with JDM may be involved by inflammation. Myocardial involvement may be evaluated by using contrast-enhanced cardiac MRI. This is the first study evaluating cardiac involvement by cardiac MRI in JDM patients. MRI may show early cardiac involvement in patients whose baseline cardiologic evaluations are within normal limits. Early detection of cardiac involvement by cardiac MRI may improve the long-term prognosis of patients with JDM.

Unveiling Cardiac Involvement in Juvenile Dermatomyositis Through Speckle-Tracking Echocardiography

Early detection of cardiac involvement in Juvenile Dermatomyositis (JDM) is difficult due to the absence of clinical signs and symptoms, with systolic dysfunction often emerging in late stages and associated with a poor prognosis. This study aimed to employ two-dimensional speckle-tracking echocardiography (STE) for subclinical assessment of left ventricular (LV) systolic failure in JDM and explore potential associations between impaired LV systolic function (LV-GLS) and disease activity. A prospective study enrolled 20 healthy volunteers and 26 JDM patients (< 18 years old) without cardiac symptoms. Clinical data were collected from medical records, and echocardiograms were conducted by a pediatric cardiologist. Our study cohort demonstrated similar age to controls (13.5 ± .6 vs. 13.8 ± 4.7; p = 0.465). Median illness duration at echocardiography was 5 (1.5-17.5) years, and conventional echocardiography indicated normal LV ejection fraction (> 55%) in all participants. However, STE revealed lowered LV GLS in JDM patients (- 22.2 ± 4.1% vs. - 26.5 ± 5.3% p = 0.022). Pulse steroid users displayed lower GLS average values compared to non-users (β = 4.99, 95% CI 1.34-8.64, p = 0.009). Negative correlations existed between LV-GLS and age at diagnosis (r = - 0.499; p = 0.011), diastolic parameters (E/E' ratio) and age at diagnosis (r = - 0.469; p = 0.018), as well as RV global strain and age at diagnosis (r = - 0.443; p = 0.024). Employing STE in JDM patients facilitated the identification of preclinical cardiac dysfunction. Given JDM patients' younger age, early myocardial damage detection through STE may impact treatment decisions and long-term cardiovascular prognosis.

Defining criteria for disease activity states in juvenile dermatomyositis based on the Juvenile Dermatomyositis Activity Index

OBJECTIVES

To develop and validate the cut-offs in the Juvenile DermatoMyositis Activity Index (JDMAI) to distinguish the states of inactive disease (ID), low disease activity (LDA), moderate disease activity (MDA) and high disease activity (HDA) in children with juvenile dermatomyositis (JDM).

METHODS

For cut-off definition, data from 139 patients included in a randomised clinical trial were used. Among the six versions of the JDMAI, JDMA1 (score range 0-40) and JDMAI2 (score range 0-39) were selected. Optimal cut-offs were determined against external criteria by calculating different percentiles of score distribution and through receiver operating characteristic curve analysis. External criteria included the modified Pediatric Rheumatology International Trials Organization (PRINTO) criteria for clinically ID in JDM (for ID) and PRINTO levels of improvement in the clinical trial (for LDA and HDA). MDA cut-offs were set at the score interval between LDA and HDA cut-offs. Cut-off validation was conducted by assessing construct and discriminative ability in two cohorts including a total of 488 JDM patients.

RESULTS

The calculated JDMAI1 cut-offs were ≤2.4 for ID, ≤6.6 for LDA, 6.7-11 for MDA and >11 for HDA. The calculated JDMAI2 cut-offs were ≤5.2 for ID, ≤8.5 for LDA, 8.6-11.3 for MDA and >11.3 for HDA. The cut-offs discriminated strongly among disease activity states defined subjectively by caring physicians and parents, parents' satisfaction or non-satisfaction with illness outcome, levels of pain, fatigue, physical functional impairment and physical well-being.

CONCLUSIONS

Both JDMAI1 and JDMAI2 cut-offs revealed good metrologic properties in validation analyses and are, therefore, suited for application in clinical practice and research.

[Advances in the diagnostics and treatment of juvenile dermatomyositis]

Juvenile dermatomyositis (JDM) is by far the most frequent inflammatory myopathy in childhood and adolescence. It is clinically characterized by inflammatory changes of the skin and muscles but as a multisystemic disease can also affect the skeletal system, the gastrointestinal tract, lungs and heart. Intrinsic (multigenetic risk) and extrinsic factors (triggers) are involved in the pathogenesis resulting in endothelial damage, involvement of fascies, activation of the interferon system and autoimmune reactions including formation of myositis-specific autoantibodies (MSA). In contrast to dermatomyositis in adults, in children and adolescents there are no associations with malignant diseases. The variable expression, the rarity of the disease and the risk of long-term damage and complications necessitate pediatric rheumatological experience in the diagnostics and treatment. Recently, new approaches in drug treatment have substantially improved the outcome and prognosis but a multidisciplinary treatment (including physicians, physiotherapists, psychologists, social workers) is mandatory, especially in the first phases of the disease. Particularly important is a professionally correct treatment of the functional sequelae, which are a particular focus of this article.

Exploring cardiovascular implications of juvenile dermatomyositis: Insights from aortic stiffness analysis and 3D echocardiography

OBJECTIVE

Our goal was to use three dimensional (3D) strain analysis to evaluate myocardial function and ascending aorta elasticity changes in juvenile dermatomyositis (JDM).

METHODS

Between 2019 and 2021, 23 JDM patients and 20 healthy volunteers participated. Both groups underwent 2D and 3D strain analysis, assessing aortic stiffness using aortic distensibility, stiffness index, strain, and elastic modulus.

RESULTS

JDM patients had a median age of 13.3 ± 5.2 years, while controls had a median age of 13.8 ± 4.76 years. 3D strain analysis revealed significantly lower global longitudinal (GLS) and circumferential strain (GCS) in JDM patients compared to controls. Specifically, 3D GLS was notably reduced in patients (-28.1% vs. -31%, p = .047) compared to controls, and 3D GCS was also lower in patients (-27.5% vs. -30.5%, p = .019) compared to controls. Aortic strain and elastic modulus were significantly lower in JDM patients, while aortic stiffness index and distensibility showed no significant differences. Correlation analyses within the JDM group revealed a negative correlation between 3D GLS and age at diagnosis (r = -.561, p = .04), as well as a positive correlation between 3D GLS and both aortic strain (r = .514, p = .0001) and elastic modulus (r = .320, p = .03) in JDM patients.

CONCLUSION

Our study demonstrated a trend towards lower ejection fraction and strain in patients with JDM, along with increased aortic stiffness using 3D echocardiography. These findings suggest potential cardiovascular involvement in juvenile dermatomyositis, emphasizing the importance of comprehensive cardiac assessments in these patients.

Lower NK cell numbers in children with untreated juvenile dermatomyositis during the COVID-19 pandemic

RNA viruses have been posited as triggers for Juvenile Dermatomyositis (JDM). The COVID-19 pandemic proved a unique opportunity to observe the effect of a novel RNA virus on JDM incidence and phenotype. We found the incidence of JDM increased from average of 6.9 cases per year from 2012 to 2019 to 9 cases per year from 2020 to 2021. We compared markers of disease activity in the patients diagnosed with JDM prior to and during the pandemic and found that patients diagnosed with JDM during the pandemic had significantly lower average NK cell counts 90.75(± 76) vs 163(±120) (P = 0.038) and NK cell percentage 3.63% (±2.3) vs. 6.6% (±4.1), (P = 0.008). Other markers of JDM did not significantly change. This study suggests that COVID-19 may be a viral trigger for JDM in selected cases and that NK cell dysregulation may be of particular interest in future research of virally triggered JDM.

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.

Body Composition and Phase Angle: How to Improve Nutritional Evaluation in Juvenile Dermatomyositis Patients

(1) Background: This study aimed to assess body composition (BC) using bioelectrical impedance and food intake in juvenile dermatomyositis (JDM) patients. Associations between BC and physical activity, disease activity/cumulative damage and health-related quality of life parameters were also evaluated; (2) Methods: This was a cross-sectional study with 30 consecutive JDM patients (18 female and 12 male) and 24 healthy volunteers (14 female and 10 male) of both sexes followed at our pediatric rheumatology unit. The gathering of anthropometric and dietary data, and the performance of physical activity and bioelectrical impedance were undertaken in face-to-face meetings and through questionnaires. Clinical and therapeutic data were collected from medical records according to information from routine medical appointments; (3) Results: The frequency of high/very high body fat was significantly higher in controls compared with JDM patients (66.7% vs. 91.7%; p = 0.046). The median phase angle was significantly lower in patients compared with controls (5.2 ± 1.3 vs. 6.1 ± 1.0; p = 0.016). Body fat and lean mass were positively correlated with disease duration (rs = +0.629, p < 0.001 and rs = +0.716, p < 0.001, respectively) and phase angle (PhA) (rs = +0.400, p = 0.029 and rs = +0.619, p < 0.001, respectively). JDM patients with PhA ≥ 5.5 presented higher lean mass when compared with patients with PhA < 5.5 (p = 0.001); (4) Conclusions: Bioelectrical impedance can be a useful auxiliary exam in the medical and nutritional follow-up of JDM patients, because it seems to impact functional ability. These findings may assist professionals when advising JDM patients about the importance of physical activity and healthy eating in the preservation of lean mass.

The von Willebrand Factor Antigen Reflects the Juvenile Dermatomyositis Disease Activity Score

OBJECTIVE

This study determined if an accessible, serologic indicator of vascular disease activity, the von Willebrand factor antigen (vWF:Ag), was useful to assess disease activity in children with juvenile dermatomyositis (JDM), a rare disease, but the most common of the pediatric inflammatory myopathies.

METHODS

A total of 305 children, median age 10 years, 72.5% female, 76.5% white, with definite/probable JDM at diagnosis, were enrolled in the Ann & Robert H. Lurie Cure JM Juvenile Myositis Repository, a longitudinal database. Disease Activity Score (DAS) and vWF:Ag data were obtained at each visit. These data were analyzed using generalized estimating equation (GEE) models (both linear and logistic) to determine if vWF:Ag reflects disease severity in children with JDM. A secondary analysis was performed for untreated active JDM to exclude the effect of medications on vWF:Ag.

RESULT

The vWF:Ag test was elevated in 25% of untreated JDM. We found that patients with elevated vWF:Ag had a 2.55-fold higher DAS total (CI₉₅: 1.83-3.27, p < 0.001). Patients with difficulty swallowing had 2.57 higher odds of elevated vWF:Ag (CI_95: 1.5-4.38, p < 0.001); those with more generalized skin involvement had 2.58-fold higher odds of elevated vWF:Ag (CI₉₅: 1.27-5.23, p = 0.006); and those with eyelid peripheral blood vessel dilation had 1.32-fold higher odds of elevated vWF:Ag (CI₉₅: 1.01-1.72, p = 0.036). Untreated JDM with elevated vWF:Ag had more muscle weakness and higher muscle enzymes, neopterin and erythrocyte sedimentation rate compared to JDM patients with a normal vWF:Ag.

CONCLUSION

vWF:Ag elevation is a widely accessible concomitant of active disease in 25% of JDM.

Early-onset juvenile dermatomyositis: A tertiary referral center experience and review of the literature

BACKGROUND/OBJECTIVES

The aim of our study is twofold: To evaluate the presentation, diagnosis, clinical course, and management of juvenile dermatomyositis (JDM) in children under three years of age, and to compare with older-onset patients.

METHODS

Nine patients with early-onset, and 63 patients with older-onset JDM followed between December 2010 and April 2022 are included. We also reviewed the literature on early-onset JDM from the inceptions of the PubMed/MEDLINE and Scopus databases up to April 1st, 2022.

RESULTS

Early-onset JDM patients were characterized by longer median diagnostic delay (p = 0.005), calcinosis (p = 0.006), anti-NXP2 antibody (p = 0.049). Diagnostic pathway included muscle biopsy (77.7% versus 50.8%). Muscle biopsy findings were more severe in the early-onset group (p<0.001). Although there was no difference in the partial and complete remission rates, the relapse rate was significantly higher in the early-onset group (p = 0.001), reflected to requirement of intravenous immunoglobulin (p = 0.001), cyclophosphamide (p = 0.011), and biological agents (p = 0.016). Literature search revealed 32 articles reporting 75 patients. The median diagnostic delay was 5 (1-30) months. Calcinosis was present in 29.5%. Twenty-three of the 44 patients (52.3%) had a muscle biopsy. Forty-one patients (64.1%) received second and third-line treatments. Complete remission was achieved in almost half of these patients (48.9%), but relapse was observed in 75%. The mortality rate was 10.2%.

CONCLUSION

Diagnosis can be challenging and delayed in early-onset JDM patients. Compared to older-onset JDM patients, this group had higher relapse rate, more severe muscle biopsy findings, and received intensive immunosuppressive treatment.

A patient-reported outcome measure for patients with pituitary adenoma undergoing transsphenoidal surgery

PURPOSE

Pituitary adenomas affect patients' quality-of-life (QoL) across several domains, with long-term implications even following gross-total resection or disease remission. While clinical outcomes can assess treatment efficacy, they do not capture variations in QoL. We present the development and validation of a patient reported outcome measure (PROM) for patients with pituitary adenomas undergoing transsphenoidal surgery.

METHODS

The COSMIN checklist informed the development of the pituitary outcome score (POS). Consecutive patients undergoing surgical treatment for suspected pituitary adenoma at a single centre were included prospectively. An expert focus group and patient interviews informed item generation. Item reduction was conducted through exploratory factor analysis and expert consensus, followed by assessment of the tool's validity, reliability, responsiveness, and interpretability.

RESULTS

96 patients with a median age of 50 years validated the POS. The final questionnaire included 25 questions with four subscales: EQ-5D-5L-QoL, Visual Symptoms, Endocrine Symptoms and Nasal Symptoms.

CONCLUSION

The POS is the first validated PROM for patients undergoing transsphenoidal surgery for a pituitary adenoma. This PROM could be integrated into contemporary practice to provide patient-centred outcomes assessment for this patient group, aligning more closely with patient objectives.

Childhood-onset Takayasu arteritis and immunodeficiency: case-based review

Takayasu arteritis (TAK) has been rarely reported in patients with immunodeficiency. In this review, we present two cases with childhood-onset TAK (c-TAK) and primary immunodeficiency while reviewing similar cases in the literature. We reviewed the data for our two pediatric patients with c-TAK and primary immunodeficiency. We also reviewed the literature for patients with c-TAK and immunodeficiency from the inceptions of the databases up to November 2021. A 14-year-old patient had lipopolysaccharide-sensitive beige-like anchor (LRBA) deficiency, and a 16-year-old had X-linked severe combined immunodeficiency (X-linked SCID). During the follow-up, they developed findings suggestive of vasculitides such as hypertension, elevation in acute phase reactants, weakness, and weight loss. Thoracoabdominal computed tomography angiography revealed findings consistent with vasculitis involving the aorta and its major branches. Patients were diagnosed with c-TAK, and corticosteroids were given to both patients in the treatment. We identified 11 articles describing 17 TAK patients with immunodeficiency in our literature search. Two of the patients with c-TAK were infected with human immunodeficiency virus (HIV), another patient had Wiskott-Aldrich syndrome, and the other had idiopathic CD4 + T lymphocytopenia. Nine adult patients with TAK were infected with HIV, three patients had common variable immunodeficiency disorder (CVID), and the other had STAT1 gain-of-function mutation. Clinicians should consider that immunodeficiencies may be accompanied by vasculitic conditions such as TAK. Hypertension, increased inflammatory markers, and constitutional symptoms may be red flags for the development of TAK.

Baseline characteristics of children with juvenile dermatomyositis enrolled in the first year of the new Childhood Arthritis and Rheumatology Research Alliance registry

BACKGROUND

To report baseline characteristics, patient reported outcomes and treatment of children with Juvenile Dermatomyositis (JDM) in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry.

METHODS

Children newly diagnosed with JDM were enrolled in the CARRA Registry from 41 pediatric rheumatology centers. Baseline patient demographics, disease characteristics, assessments, patient reported outcome and treatments were recorded.

RESULTS

In the first year, 119 JDM participants were enrolled. Most were female (63.4%), and white (72.3%) with a median diagnosis age 8.0 years (IQR 4.0-11.5), and median age of disease onset 7.0 years (IQR 3.5-7.5). They had characteristic rashes (92.4%), elevated muscle enzymes (83.2%), physician global score 4.0 (IQR 2.5-5.0) and manual muscle testing score 63.5 (IQR 51.0-75.0). Calcinosis (3.4%) and interstitial lung disease (< 1%) were uncommon. Myositis specific antibodies were measured and reported in nearly half of participants enrolled where anti-MJ followed by Anti-p155/140 were most common (11/49 and 7/53 respectively). Childhood Health Assessment Questionnaire (CHAQ) results showed mild-moderate disability (median 0.750, IQR 0.030-1.875), as did patient/parent global assessments of disease activity (median 3, patient IQR: 1.75-5.25; parent IQR: 1-7). Patient Reported Outcomes Measurement Information System (PROMIS®) Pediatric Global Health 7 scores, Pain Interference, Physical Function scores for Mobility, and Upper Extremity Function were commonly worse than 95% of the general pediatric population.

CONCLUSIONS

In its inaugural year, 119 JDM patients were successfully enrolled in participapte in the New CARRA Registy. This registry will provide the necessary foundation to advance clinical research to improve outcomes using traditional measures and patient reported outcomes. With the CARRA biorepository, this infrastructure will enable future translational research. Together, these efforts may aid in future clinical trials, including comparative effectiveness trials.

Muscle biopsy in myositis: What the rheumatologist needs to know

The appropriate analysis of skeletal muscle tissues is a key element in many diagnostic procedures and can deliver valuable information about the organ that is affected. Although arguably the frequency of muscle biopsy may be declining in certain domains where genetic analysis is now the first line of diagnostic evaluation, it still has an important role in assessment of patients with neuromuscular disorders such as congenital myopathies, muscular dystrophies, metabolic and inflammatory diseases. Here, we have comprehensively discussed the aspects of a modern and fruitful approach to muscle biopsy histopathological studies in rheumatological disorders. We have focussed on the neuromuscular involvement in myositis and its differential diagnoses in both adult and paediatric settings. We have also covered the clinical indications for the biopsy, technical aspects and practical points relevant for the rheumatologists. Finally, we have critically discussed the current and future opportunities that a muscle biopsy may offer and its limitations.

[Dermatomyositis and juvenile dermatomyositis]

Dermatomyositis (DM) is an inflammatory multisystem disease of unknown etiology, which can already occur in children but first onset can also be in older adulthood. Myalgia and muscle weakness can occur later in the course of the disease or even be completely absent in some forms. Classical signs on the skin include heliotrope rash, facial erythema, Gottron's papules and nailfold capillary abnormalities. For the diagnosis, screening for the presence of myositis-specific autoantibodies has become increasingly more relevant. Muscle enzymes may be elevated but not in approximately one third of patients. In the absence of typical clinical or serologic findings, additional examination methods such as nailfold capillaroscopy, magnetic resonance imaging, electromyography, skin or muscle biopsies may help to establish the diagnosis. Depending on the clinical and serological subtype, additional screening for gastrointestinal or cardiopulmonary involvement should be considered. In adults, an age-appropriate tumor screening should also be performed. Apart from corticosteroids as induction therapy, biologics and small molecule inhibitors are gaining in importance in addition to conventional disease-modifying anti-rheumatic drugs and intravenous immunoglobulins. The prognosis for DM and juvenile DM (JDM) has improved. Most patients recover at least to some extent; however, a few patients die and a minority develop persisting muscle atrophy or severe calcinosis.

Feasibility of the wingate anaerobic exercise test as a clinical measure in patients with juvenile dermatomyositis

BACKGROUND

Core sets, while widely adopted for clinical assessment in juvenile dermatomyositis (JDM), have some drawbacks - they are time consuming, were developed primarily for research, and require an experienced multidisciplinary team. We propose the Wingate Anaerobic Test, a 30-s all out test performed on a cycle ergometer, as a potential alternative; it is valid and reliable in this patient population. We aimed to determine the feasibility of performing the Wingate test as part of a typical clinic visit, and to determine if it is correlated to current measures of disease activity.

METHODS

Patients 5-18 years of age, with JDM, were recruited from the JDM clinic at a large Canadian academic children's hospital. Participants underwent a standard clinic assessment, then completed a Wingate test at the end of the visit.

RESULTS

Twenty-six patients participated in the study, representing a recruitment rate of 81%; of those, 88% were able to complete the Wingate test. Patients liked the Wingate test and felt it should be included as a regular clinic test. Absolute peak power (watts) on the Wingate test was strongly correlated to the manual muscle test (MMT-8) and the timed squat test. Relative peak power (watts/kg) on the Wingate test was strongly correlated to the timed squat test and the Childhood Myositis Assessment Scale (CMAS). Exploratory principal components analysis revealed that Wingate relative average power explained almost 2/3 of the variance of the CMAS, MMT and timed squats combined.

CONCLUSION

The Wingate test is a feasible test for children with JDM and correlates well with standard clinical assessments. Given its brevity, it has the potential to replace more standard measures of physical function currently used in clinical assessments for children with JDM. Future work should focus on how best to operationalize Wingate testing in clinic without the use of dedicated personnel.

SIGLEC1 enables straightforward assessment of type I interferon activity in idiopathic inflammatory myopathies

Objective

To evaluate sialic acid binding Ig-like lectin 1 (SIGLEC1) expression on monocytes by flow cytometry as a type I interferon biomarker in idiopathic inflammatory myopathies (IIM).

Methods

We performed a retrospective analysis of adult and paediatric patients with the diagnosis of IIM. SIGLEC1 expression was assessed by flow cytometry and was compared with Physician Global Assessment or Childhood Myositis Assessment Scale disease activity scores. Mann Whitney U test and receiver operating characteristic curves were used for cross-sectional data analysis (n=96), two-level mixed-effects linear regression model for longitudinal analyses (n=26, 110 visits). Response to treatment was analysed in 14 patients within 12 months, using Wilcoxon test. SIGLEC1 was compared with interferon-stimulated gene 15/MxA status by immunohistochemical staining of muscle biopsies (n=17).

Results

96 patients with adult (a) and juvenile (j) dermatomyositis (DM, n=38), antisynthetase syndrome (AS, n=19), immune-mediated necrotising myopathy (IMNM, n=8), inclusion body myositis (IBM, n=9) and overlap myositis (n=22) were included. SIGLEC1 distinguished significantly between active and inactive disease with an area under the curve of 0.92 (95% CI 0.83 to 1) in DM and correlated with disease activity longitudinally (aDM: standardised beta=0.54, p<0.001; jDM: standardised beta=−0.70, p<0.001). Response to treatment in DM was associated with a decreasing SIGLEC1 (p<0.01, Wilcoxon test). SIGLEC1 was found upregulated in 8 of 19 patients with AS, 2 of 9 patients with IBM but not in IMNM.

Conclusion

SIGLEC1 is a candidate biomarker to assess type I interferon activity in IIM and proved useful for monitoring disease activity and response to treatment in juvenile and adult DM.

Juvenile Dermatomyositis

Juvenile dermatomyositis (JDM) is a systemic capillary vasculopathy. Patients present with proximal muscle weakness, raised muscle enzymes, and pathognomic skin rashes such as heliotrope rash, Gottron's papules. Main complications are calcinosis, lipodystrophy, osteoporosis. Complement-mediated damage of vessels is a major mechanism. Magnetic resonance imaging is currently widely used to diagnosis of JDM. The goals of treatment are to control inflammatory myositis and prevent disease complication. Early, aggressive treatment of JDM associated with a better prognosis. High-dose corticosteroids in combination with methotrexate is the mainstay of treatment. The course of JDM is variable.

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.

The Vasculopathy of Juvenile Dermatomyositis: Endothelial Injury, Hypercoagulability, and Increased Arterial Stiffness

OBJECTIVE

Vasculopathy is considered central to the pathogenesis of juvenile dermatomyositis (DM) and is associated with severe extramuscular manifestations. We undertook this study to investigate the hypothesis that the vasculopathy of juvenile DM can be noninvasively tracked by examining biomarkers of endothelial injury, subclinical inflammation, hypercoagulability, and vascular arterial stiffness.

METHODS

The study population was a UK cohort of children with juvenile DM. Circulating endothelial cells (CECs) and microparticles (MPs) were identified using immunomagnetic bead extraction and flow cytometry, respectively. Plasma thrombin generation was determined using a fluorogenic assay. Cytokine and chemokine levels were measured by electrochemiluminescence. Arterial stiffness was assessed using pulse wave velocity (PWV). Results were expressed as the median and interquartile range (IQR), and statistical significance was assessed using nonparametric analyses.

RESULTS

Ninety patients with juvenile DM and 79 healthy control subjects were included. The median age of the patients was 10.21 years (IQR 6.68-13.40), and the median disease duration was 1.63 years (IQR 0.28-4.66). CEC counts were higher in all patients with juvenile DM compared to controls (median 96 cells/ml [IQR (40-192] and 12 cells/ml [IQR 8-24], respectively; P < 0.0001). Circulating MP numbers were also significantly higher in patients with active juvenile DM compared to controls (median 204.7 × 103 /ml [IQR 87.9-412.6] and 44.3 × 103 /ml [IQR 15.0-249.1], respectively; P < 0.0001). MPs were predominantly of platelet and endothelial origin. Enhanced plasma thrombin generation was demonstrated in patients with active juvenile DM compared to those with inactive disease (P = 0.0003) and controls (P < 0.0001). Carotid-radial PWV adjusted for age was increased in patients with juvenile DM compared to controls (P = 0.003).

CONCLUSION

We observed increased endothelial injury and increased levels of proinflammatory cytokines in patients with active juvenile DM. MP profiles reflected distinct disease activity status in juvenile DM and are markers of vascular pathology, platelet activation, and thrombotic propensity. Ongoing long-term vascular injury may result in increased arterial stiffness in patients with juvenile DM.

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.

Juvenile Dermatomyositis: Advances in Pathogenesis, Assessment, and Management

BACKGROUND

Juvenile dermatomyositis is the most common inflammatory myopathy in the pediatric age group and a major cause of mortality and morbidity in individuals with childhood rheumatic diseases. Mounting evidence suggests that early diagnosis and timely aggressive treatment are associated with better outcomes.

OBJECTIVE

The purpose of this article is to provide readers with an update on the evaluation, diagnosis, and the treatment of juvenile dermatomyositis.

METHODS

A PubMed search was performed in Clinical Queries using the key term "juvenile dermatomyositis" in the search engine. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Juvenile dermatomyositis is a chronic autoimmune inflammatory condition characterized by systemic capillary vasculopathy that primarily affects the skin and muscles with possible involvement of other organs. In 2017, the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) developed diagnostic criteria for juvenile idiopathic inflammatory myopathies and juvenile dermatomyositis. In the absence of muscle biopsies which are infrequently performed in children, scores (in brackets) are assigned to four variables related to muscle weakness, three variables related to skin manifestations, one variable related to other clinical manifestations, and two variables related to laboratory measurements to discriminate idiopathic inflammatory myopathies from non-idiopathic inflammatory myopathies as follows: objective symmetric weakness, usually progressive, of the proximal upper extremities (0.7); objective symmetric weakness, usually progressive, of the proximal lower extremities (0.8); neck flexors relatively weaker than neck extensors (1.9); leg proximal muscles relatively weaker than distal muscles (0.9); heliotrope rash (3.1); Gottron papules (2.1); Gottron sign (3.3); dysphagia or esophageal dysmotility (0.7); the presence of anti-Jo-1 autoantibody (3.9); and elevated serum levels of muscle enzymes (1.3). In the absence of muscle biopsy, a definite diagnosis of idiopathic inflammatory myopathy can be made if the total score is ≥7.5. Patients whose age at onset of symptoms is less than 18 years and who meet the above criteria for idiopathic inflammatory myopathy and have a heliotrope rash, Gottron papules or Gottron sign are deemed to have juvenile dermatomyositis. The mainstay of therapy at the time of diagnosis is a high-dose corticosteroid (oral or intravenous) in combination with methotrexate.

CONCLUSION

For mild to moderate active muscle disease, early aggressive treatment with high-dose oral prednisone alone or in combination with methotrexate is the cornerstone of management. Pulse intravenous methylprednisolone is often preferred to oral prednisone in more severely affected patients, patients who respond poorly to oral prednisone, and those with gastrointestinal vasculopathy. Other steroid-sparing immunosuppressive agents such as cyclosporine and cyclophosphamide are reserved for patients with contraindications or intolerance to methotrexate and for refractory cases, as the use of these agents is associated with more adverse events. Various biological agents have been used in the treatment of juvenile dermatomyositis. Data on their efficacy are limited, and their use in the treatment of juvenile dermatomyositis is considered investigational.

Development and Testing of Reduced Versions of the Manual Muscle Test-8 in Juvenile Dermatomyositis

OBJECTIVE

To develop and test shortened versions of the Manual Muscle Test-8 (MMT-8) in juvenile dermatomyositis (JDM).

METHODS

Construction of reduced tools was based on a retrospective analysis of individual scores of MMT-8 muscle groups in 3 multinational datasets. The 4 and 6 most frequently impaired muscle groups were included in MMT-4 and MMT-6, respectively. Metrologic properties of reduced tools were assessed by evaluating construct validity, internal consistency, discriminant ability, and responsiveness to change.

RESULTS

Neck flexors, hip extensors, hip abductors, and shoulder abductors were included in MMT-4, whereas MMT-6 also included elbow flexors and hip flexors. Both shortened tools revealed strong correlations with MMT-8 and other muscle strength measures. Correlations with other JDM outcome measures were in line with predictions. Internal consistency was good (0.88-0.96) for both MMT-4 and MMT-6. Both reduced tools showed strong ability to discriminate between disease activity states, assessed by the caring physician or a parent (P < 0.001), and between patients whose parents were satisfied or not satisfied with illness course (P < 0.001). Responsiveness to change (assessed by both standardized response mean and relative efficiency) of MMT-4 and, to a lesser degree, MMT-6, was slightly superior to that of MMT-8.

CONCLUSION

Overall, the metrologic performance of MMT-4 and MMT-6 was comparable to that of the other established muscle strength tools, which indicates that they may be suitable for use in clinical practice and research, including clinical trials. The measurement properties of these tools should be further tested in other patient populations and evaluated prospectively.

Echocardiographic study of juvenile dermatomyositis patients: new insights from speckle-tracking-derived strain

OBJECTIVES

This study aimed to investigate subclinical left ventricle (LV) systolic dysfunction in juvenile dermatomyositis (JDM) using two-dimensional speckle-tracking echocardiography (2DST). Possible associations between LV deformation impairment and disease activity/cumulative damage were also evaluated.

METHODS

Thirty-five consecutive JDM patients without cardiac symptoms and 35 healthy volunteers were enrolled. Clinical data were collected from medical records, and echocardiograms were performed by a pediatric cardiologist, unaware of patients' conditions.

RESULTS

Patients and controls had similar age (12.6 ± 0.7 vs.12.5 ± 0.6; p = 0.97) and gender (11F:24M vs.11F:24M; p = 1.0). Median of JDM duration was 4.6 (0.04-17.6) years, and only 6/35 (17%) had active disease (disease activity score (DAS > 3)). Conventional echocardiogram revealed preserved LV ejection fraction (EF) (≥ 55%) in all individuals. In JDM, 2DST identified reduction of LV longitudinal [-22(-17.2 to -27.9) % vs. -23(-20.8 to -27.4) %; p = 0.028)] and circumferential -23.9 ± 2.8% vs. -26.7 ± 2.9%; p = 0.0002) strain. Lower longitudinal strain was associated with DAS >3 -19.9(-17.2 to -26.5)% vs. -22.1-18.9 to -27.9)%; p = 0.046], MDI extent > 0 [-19(-17.2 to -22.5)% vs. -22.1-19.2 to -27.9)%; p = 0.0008], MDI severity > 0 [-19(-17.2 to -22.1)% vs. -22.3(-20.3 to -27.9)%; p = 0.0001] and calcinosis[-20.6(-17.2 to -23)% vs. -22.3(-20.3 to -27.9)%; p = 0.03]. Lower circumferential strain was associated with MDI extent > 0 (-22.1 ± 3.87% vs. -24.4 ± 2.3%; p = 0.039), MDI severity > 0 (-21.7 ± 3% vs. 24.7 ± 2.3%; p = 0.004) and calcinosis (-22.5 ± 3.3% vs. -24.8 ± 2.1%; p = 0.02). There was a negative correlation between longitudinal strain and cumulative dose of prednisone (r = -0.44; p = 0.009) and methotrexate (r = -0.33; p = 0.0008).

CONCLUSIONS

LV 2DST detected early systolic myocardial compromise in asymptomatic pediatric JDM patients, with preserved EF. Longitudinal strain impairment was associated with disease activity and cumulative damage, whereas circumferential strain impairment was associated exclusively with cumulative damage.

KEY POINTS

• Serious cardiac involvement is rare but has been associated with death in juvenile dermatomyositis. • Two-dimensional speckle tracking stands out for the identification of subclinical myocardial compromise in juvenile dermatomyositis. • Longitudinal strain impairment is associated with disease activity and cumulative damage, whereas circumferential strain impairment is associated exclusively with cumulative damage.

Retrospective analysis of infliximab and adalimumab treatment in a large cohort of juvenile dermatomyositis patients

BACKGROUND

Anti-TNF treatment may be useful for the treatment of patients with refractory juvenile dermatomyositis (JDM). The aim of this study was to describe the use of infliximab and adalimumab therapy in juvenile dermatomyositis as an adjunctive treatment.

METHODS

Sixty children recruited to the UK JDM Cohort and Biomarker Study that had received at least 3 months of anti-TNF treatment (infliximab or adalimumab) were studied. Childhood Myositis Assessment Scale (CMAS), Manual Muscle Testing (MMT8) and physician's global assessment (PGA) were recorded. Skin disease was assessed using the modified skin disease activity score (DAS). Data were analysed using Friedman's test for repeated measures analysis of variance.

RESULTS

Compared to baseline, there were improvements at 6 and 12 months in skin disease (χ2(2) = 15.52, p = 0.00043), global disease (χ2(2) = 8.14, p = 0.017) and muscle disease (CMAS χ2(2) = 17.02, p = 0.0002 and MMT χ2(2) = 10.56, p = 0.005) in infliximab patients. For patients who switched from infliximab to adalimumab, there was improvement in global disease activity (χ2(2) = 6.73, p = 0.03), and trends towards improvement in CMAS, MMT8 and modified DAS. The median initial prednisolone dose was 6 [0-10] mg, and final was 2.5 [0-7.5] mg (p < 0.0001). Fifty-four per cent of patients had a reduction in the number and/or size of calcinosis lesions. Twenty-five per cent switched their anti-TNF treatment from infliximab to adalimumab. 66.7%of the switches were to improve disease control, 26.7% due to adverse events and 6.6% due to patient preference. A total of 13.9 adverse reactions occurred in 100 patient-years, of which 5.7 were considered serious.

CONCLUSION

Reductions in muscle and skin disease, including calcinosis, were seen following treatment with infliximab and adalimumab.

Pilot Study of the Juvenile Dermatomyositis Consensus Treatment Plans: A CARRA Registry Study

OBJECTIVES

To determine the feasibility of comparing the Childhood Arthritis and Rheumatology ResearchAlliance (CARRA) consensus treatment plans (CTP) in treating moderate new-onset juvenile dermatomyositis (JDM) using the CARRA registry, and to establish appropriate analytic methods to control for confounding by indication and missing data.

METHODS

A pilot cohort of 39 patients with JDM from the CARRA registry was studied. Patients were assigned by the treating physician, considering patient/family preferences, to 1 of 3 CTP: methotrexate (MTX) and prednisone (MP); intravenous (IV) methylprednisolone, MTX, and prednisone (MMP); or IV methylprednisolone, MTX, prednisone, and IV immunoglobulin (MMPI). The primary outcome was the proportion of patients achieving moderate improvement at 6 months under each CTP. Statistical methods including multiple imputation and inverse probability of treatment weighting were used to handle missing data and confounding by indication.

RESULTS

Patients received MP (n = 13), MMP (n = 18) and MMPI (n = 8). Patients in all CTP had significant improvement in disease activity. Of the 36 patients who remained in our pilot study at 6 months, 16 (44%) of them successfully achieved moderate improvement at 6 months (6/13, 46% for MP; 7/15, 47% for MMP; 3/8, 38% for MMPI). After correcting for confounding, there were no statistically significant pairwise differences between the CTP (P = 0.328-0.88).

CONCLUSION

We gained valuable experience and insight from our pilot study that can be used to guide the design and analysis of comparative effectiveness studies using the CARRA registry CTP approach. Our analytical methods can be adopted for future comparative effectiveness studies and applied to other rare disease observational studies.

Long-term outcome in children with juvenile dermatomyositis: A single-center study from north India

INTRODUCTION

Juvenile dermatomyositis (JDM) is the commonest childhood inflammatory myopathy. Outcome of children with JDM has improved significantly with current treatment protocols. We undertook this study to evaluate long-term outcome of these children using validated outcome measures.

METHODS

All children diagnosed as JDM and on follow-up for more than 2 years were eligible for enrolment. Cross-sectional examination was performed to assess signs of disease activity, damage, physical function and complications by using multiple validated outcome measures/tools.

RESULTS

Thirty-seven patients were enrolled, 19 were male. Median duration of disease at time of enrolment was 73 months (range 24-219 months) and median duration of follow-up was 60 months (range 24-218 months). Disease course was monocyclic in two-thirds of patients. Eight children were still on therapy at the time of enrolment. On Manual Muscle Testing 8, 3 and 7 children had severe weakness and mild to moderate weakness, respectively. Neck flexors were the most commonly affected muscle group. On abbreviated Cutaneous Assessment Tool, 14 children had evidence of cutaneous activity. More than 50% had at least 1 sign of cutaneous damage, most common signs being calcinosis and lipodystrophy. Nearly two-thirds of patients had damage in at least 1 organ using Myositis Damage Index. Nine children had physical dysfunction when assessed by Child Health Assessment Questionnaire.

CONCLUSIONS

Skin disease continued to be active in a significant proportion of patients. Features of damage, namely calcinosis and lipodystrophy, were seen in more than half. Muscle disease normalized in a large proportion of patients.

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.

Paediatric and adolescent rheumatic diseases: measures of disease activity

Juvenile idiopathic arthritis, juvenile systemic lupus erythematosus and juvenile dermatomyositis are rare, chronic, multi-systemic rheumatic disorders that can be associated with significant morbidity, not only during childhood, but lifelong. Dedicated disease activity and damage assessment tools are essential to guide clinical management and perform multicentre clinical trials to ensure the best possible care and outcome for children with rheumatic diseases using an evidence-based, treat-to-target approach. This article summarizes the outcome measures most commonly used in paediatric rheumatology.

Muscle Expression of Type I and Type II Interferons Is Increased in Juvenile Dermatomyositis and Related to Clinical and Histologic Features

OBJECTIVE

To evaluate the expression of type I interferon (IFNα/β)- and type II IFN (IFNγ)-inducible genes in muscle biopsy specimens from patients with juvenile dermatomyositis (DM) and to correlate their expression levels with histologic and clinical features.

METHODS

Expression levels of IFN-inducible genes and proinflammatory cytokines were assessed by quantitative polymerase chain reaction in muscle biopsy specimens from patients with juvenile DM (n = 39), patients with Duchenne's muscular dystrophy (DMD), and healthy controls. Muscle biopsy sections were stained and scored for severity of histopathologic features. The charts of patients with juvenile DM were reviewed for clinical features at the time of sampling and long-term outcomes.

RESULTS

Muscle expression levels of IFNα/β-inducible genes (type I IFN score), IFNγ, IFNγ-inducible genes (type II IFN score), and tumor necrosis factor (TNF) were significantly higher in juvenile DM patients not receiving glucocorticoid therapy before muscle biopsy (n = 27) compared to DMD patients (n = 24) (type I IFN score, P < 0.0001; type II IFN score, P < 0.001; TNF, P < 0.05) and healthy controls (n = 4) (type I IFN score, P < 0.01; type II IFN score, P < 0.01; TNF, P < 0.05). Immunofluorescence staining of muscle biopsy sections from untreated juvenile DM patients showed increased immunoreactivity for IFNγ and HLA class II molecules compared to controls. Type I and type II IFN scores were correlated with typical histopathologic features of juvenile DM muscle biopsy samples, such as infiltration of endomysial CD3+ cells (type I IFN score, r = 0.68; type II IFN score, r = 0.63), perimysial CD3+ cells (type I IFN score, r = 0.59; type II IFN score, r = 0.66), CD68+ cells (type II IFN score, r = 0.46), and perifascicular atrophy (type I IFN score, r = 0.61; type II IFN score, r = 0.77). Juvenile DM patients with a high type I IFN score, a high type II IFN score, and high TNF expression levels showed more severe disease activity at biopsy (P < 0.05). In addition, juvenile DM patients with a high type II IFN score at biopsy reached clinically inactive disease significantly later than patients with low type II IFN score (log rank chi-square value 13.53, P < 0.001).

CONCLUSION

The increased expression of IFN-inducible genes in the muscle in juvenile DM patients and their association with histologic and clinical features further support a pathogenic role for both type I and type II IFNs in juvenile DM.

Increased Soluble Cytoplasmic Bcl-2 Protein Serum Levels and Expression and Decreased Fas Expression in Lymphocytes and Monocytes in Juvenile Dermatomyositis

OBJECTIVE

To evaluate soluble Fas antigen (sFas), sFas ligand (sFasL), soluble tumor necrosis factor-related apoptosis-inducing ligand, and soluble cytoplasmic Bcl-2 protein (sBcl-2) serum levels, Fas and Bcl-2 expressions in T and B lymphocytes and monocytes and relations with erythrocyte sedimentation rate, C-reactive protein (CRP), Childhood Myositis Assessment Scale, and manual muscle testing in juvenile dermatomyositis (JDM).

METHODS

Serum levels were determined by ELISA and peripheral cell expressions by flow cytometry for patients with JDM or juvenile idiopathic arthritis (JIA), and healthy controls.

RESULTS

Patients with JDM had increased sBcl-2, which correlated with CRP. Expression of Bcl-2 was increased and expression of Fas was decreased in CD3+, CD4+, and CD8+ T lymphocytes compared with JIA and/or healthy controls.

CONCLUSION

Patients with JDM presented a unique apoptosis-related proteins profile, which may contribute to disease development.

Juvenile Idiopathic Inflammatory Myopathies

The juvenile idiopathic inflammatory myopathies (JIIM) are a group of rare, chronic, autoimmune illnesses that affect muscle and, to a lesser extent, skin. The presence of new-onset weakness and, in juvenile dermatomyositis, typical rahes, should lead to consideration of these diagnoses. Careful evaluation to exclude alternative diagnoses is needed. Investigations include a variety of blood tests, imaging, and possibly muscle biopsy. Validated clinical assessments are available for monitoring. Standard treatment includes corticosteroids and methotrexate and often extends beyond 1 year. Outcomes are generally good, but disease persistence remains problematic. Early involvement of providers with expertise in JIIM is essential.

CD19+CD24hiCD38hi B Cells Are Expanded in Juvenile Dermatomyositis and Exhibit a Pro-Inflammatory Phenotype After Activation Through Toll-Like Receptor 7 and Interferon-α

Juvenile dermatomyositis (JDM) is a rare form of childhood autoimmune myositis that presents with proximal muscle weakness and skin rash. B cells are strongly implicated in the pathogenesis of the disease, but the underlying mechanisms are unknown. Therefore, the main objective of our study was to investigate mechanisms driving B cell lymphocytosis and define pathological features of B cells in JDM patients. Patients were recruited through the UK JDM Cohort and Biomarker study. Peripheral blood B cell subpopulations were immunophenotyped by flow cytometry. The results identified that immature transitional B cells were significantly expanded in active JDM, actively dividing, and correlated positively with disease activity. Protein and RNAseq analysis revealed high interferon alpha (IFNα) and TLR7-pathway signatures pre-treatment. Stimulation of B cells through TLR7/8 promoted both IL-10 and IL-6 production in controls but failed to induce IL-10 in JDM patient cells. Interrogation of the CD40–CD40L pathway (known to induce B cell IL-10 and IL-6) revealed similar expression of IL-10 and IL-6 in B cells cultured with CD40L from both JDM patients and controls. In conclusion, JDM patients with active disease have a significantly expanded immature transitional B cell population which correlated with the type I IFN signature. Activation through TLR7 and IFNα may drive the expansion of immature transitional B cells in JDM and skew the cells toward a pro-inflammatory phenotype.

Expression of myxovirus-resistance protein A: a possible marker of muscle disease activity and autoantibody specificities in juvenile dermatomyositis

Aims

To evaluate the relationship between expression of myxovirus‐resistance protein A (MxA) protein on muscle biopsies by immunohistochemistry and disease activity in juvenile dermatomyositis (JDM) patients. Also, another aim was to investigate whether the expression of MxA is related with myositis‐specific autoantibodies (MSA) status in JDM patients.

Methods

103 patients (median aged 6.3, interquartile range 0.5–15.9) enrolled in the Juvenile Dermatomyositis Cohort and Biomarker Study (JDCBS). Muscle biopsies were stained with MxA and scored. Clinical data at initial presentation were collected and autoantibodies were analysed. Multiple linear regression analysis was performed to estimate the association between MxA expression on muscle fibres and muscle disease activity, and MSA status.

Results

Expression of MxA protein on JDM samples was identified in 61.2%. There was a significant association between MxA scores and Childhood Myositis Assessment Scale (CMAS) (P = 0.002), and Manual Muscle Testing of Eight Muscles (MMT8) (P = 0.026). CMAS and MMT8 scores were significantly lower in the group of patients with strong MxA expression. MxA scores differed according to MSA subgroups (P = 0.002). Patients with positive nuclear matrix protein 2 autoantibodies had strong MxA expression, whereas anti‐melanoma differentiation‐associated gene 5 positive patients had no or weak MxA expression.

Conclusions

This study reveals the significant association between level of MxA expression on muscle fibres and clinical measures of muscular disease activity in JDM patients and MSA status. This confirms type I interferonopathies in muscle fibres of JDM patients which could help with improving treatment outcome in JDM patients and underscoring the distinct pathophysiological pathways in different MSA status.

Efficacy and Safety of Cyclophosphamide Treatment in Severe Juvenile Dermatomyositis Shown by Marginal Structural Modeling

OBJECTIVE

In patients with severe or refractory juvenile dermatomyositis (DM), second-line treatments may be required. Cyclophosphamide (CYC) is used to treat some connective tissue diseases, but evidence of its efficacy in juvenile DM is limited. This study was undertaken to describe clinical improvement in juvenile DM patients treated with CYC and model the efficacy of CYC treatment compared to no CYC treatment.

METHODS

Clinical data on skin, global, and muscle disease for patients recruited to the Juvenile DM Cohort and Biomarker Study were analyzed. Clinical improvement following CYC treatment was described using unadjusted analysis. Marginal structural models (MSMs) were used to model treatment efficacy and adjust for confounding by indication.

RESULTS

Compared to the start of CYC treatment, there were reductions at 6, 12, and 24 months in skin disease (P = 1.3 × 10-10 ), global disease (P = 2.4 × 10-8 ), and muscle disease (P = 8.0 × 10-10 ) for 56 patients treated with CYC in unadjusted analysis. Limited evidence suggested a reduction in glucocorticoid dose (P = 0.047) in patients treated with CYC. MSM analysis showed reduced global disease and skin disease in patients who started an ~6-month course of CYC treatment >12 months ago compared to patients never or not yet treated with CYC. In the treated patients, the modified skin Disease Activity Score for juvenile DM was 1.19 units lower (P = 0.0085) and the physician's global assessment was 0.66 units lower (P = 0.027). Minor adverse events were reported in 3 patients within 1 year of stopping CYC.

CONCLUSION

Our findings indicate that CYC is efficacious with no short-term side effects. Improvements in skin, global, and muscle disease were observed. Further studies are required to evaluate longer-term side effects.

Predictors of changes in disease activity among children with juvenile dermatomyositis enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Legacy Registry

Determinants of changes in disease activity among patients with juvenile dermatomyositis (JDM) are unknown. Our objective was to develop predictive models to predict changes in disease activity using the CARRA Legacy Registry. The CARRA Legacy Registry included 658 subjects with definite or probably JDM with 297 subjects with a one follow-up visit after baseline, and we studied the 65 subjects with active disease at baseline. Linear regression models were used to build risk scores for changes in disease activity adjusted for baseline disease activity, age, sex, and disease duration. Disease activity improved from baseline to 6-month follow-up as measured by patient/parent global health score (median 4; p = 0.008), patient pain score (median 2; p = 0.014), physician global (median 4; p < 0.001), and Childhood Myositis Assessment Scale (CMAS) (median 41, p < 0.001). Anti-nuclear antibodies (p = 0.013) and hydroxychloroquine use (p = 0.045) were significant predictors of less improvement in patient/parent global and baseline patient/parent global. Anti-nuclear antibodies (p = 0.001) and V/shawl sign (p = 0.005) were significant predictors of less improvement in patient pain (R-square improved from 0.29 for adjustors alone to 0.46 for the full model). Small joint arthritis (p < 0.01) predicted less improvement and dysphagia/dysphonia (p = 0.033) predicted greater improvement in CMAS and baseline CMAS (R-square improved from 0.73 for adjustors alone to 0.86 for the full model). Disease characteristics can help identify patients who are less likely to improve over time. Risk scores to predict future changes in disease activity could be used to trigger more aggressive treatment earlier in the disease course.

Autoantibodies in juvenile-onset myositis: Their diagnostic value and associated clinical phenotype in a large UK cohort

OBJECTIVES

Juvenile myositis is a rare and heterogeneous disease. Diagnosis is often difficult but early treatment is important in reducing the risk of associated morbidity and poor outcomes. Myositis specific autoantibodies have been described in both juvenile and adult patients with myositis and can be helpful in dividing patients into clinically homogenous groups. We aimed to explore the utility of myositis specific autoantibodies as diagnostic and prognostic biomarkers in patients with juvenile-onset disease.

METHODS

Using radio-labelled immunoprecipitation and previously validated ELISAs we examined the presence of myositis specific autoantibodies in 380 patients with juvenile-onset myositis in addition to, 318 patients with juvenile idiopathic arthritis, 21 patients with juvenile-onset SLE, 27 patients with muscular dystrophies, and 48 healthy children.

RESULTS

An autoantibody was identified in 60% of juvenile-onset myositis patients. Myositis specific autoantibodies (49% patients) were exclusively found in patients with myositis and with the exception of one case were mutually exclusive and not found in conjunction with another autoantibody. Autoantibody subtypes were associated with age at disease onset, key clinical disease features and treatment received.

CONCLUSIONS

In juvenile patients the identification of a myositis specific autoantibody is highly suggestive of myositis. Autoantibodies can be identified in the majority of affected children and provide useful prognostic information. There is evidence of a differential treatment approach and patients with anti-TIF1γ autoantibodies are significantly more likely to receive aggressive treatment with IV cyclophosphamide and/or biologic drugs, clear trends are also visible in other autoantibody subgroups.

Submaximal Exercise Capacity in Juvenile Dermatomyositis after Longterm Disease: The Contribution of Muscle, Lung, and Heart Involvement

OBJECTIVE

To compare submaximal exercise capacity in patients with juvenile dermatomyositis (JDM) with controls, and analyze contributions of muscle, heart, and lung impairment in patients.

METHODS

Fifty-nine patients with JDM, with a mean 16.9 years after symptom onset, and 59 sex- and age-matched controls completed a 6-min walk test (6MWT) and a timed up and go (TUG) test. Muscle function, disease activity/damage, and health-related quality of life (HRQOL) were assessed by validated tools; heart function by echocardiography and electrocardiography; and lung function by spirometry, DLCO, and body plethysmography. A thoracic high-resolution computed tomography (HRCT) scan and magnetic resonance imaging of the thighs were completed in patients.

RESULTS

The 6MWT distance (6MWD) was 592 ± 81 m in patients versus 649 ± 79 m in controls (p < 0.001), and 563 ± 75 m in active versus 622 ± 76 m in inactive JDM (p = 0.004). The TUG time was 13.1 ± 2.1 s in patients versus 12.3 ± 2.0 s in controls (p = 0.034), and 13.7 ± 2.2 s in active versus 12.5 ± 1.8 s in inactive JDM (p = 0.028). No statistically significant difference was found between inactive JDM and controls in either test. In patients, the Childhood Myositis Assessment Score influenced the 6MWD and TUG time the most, followed by a low DLCO and HRCT pathology in the 6MWT and forced vital capacity in the TUG test. Medical Outcomes Study Short Form-36 physical component summary correlated strongly with both tests.

CONCLUSION

Submaximal exercise capacity was reduced in patients with JDM, particularly those with active disease. This reduction was associated with muscle and lung dysfunction and poorer HRQOL.

Anti-HMGCR Autoantibodies in Juvenile Idiopathic Inflammatory Myopathies Identify a Rare but Clinically Important Subset of Patients

Objective.

We aimed to establish the prevalence and clinical associations of anti-HMG-CoA-reductase (anti-HMGCR) in a large UK cohort with juvenile myositis.

Methods.

There were 381 patients investigated for anti-HMGCR using ELISA.

Results.

Anti-HMGCR autoantibodies were detected in 4 patients (1%). These children had no or minimal rash and significant muscle disease. Muscle biopsies were considered distinctive, with widespread variation in fiber size, necrotic fibers, and chronic inflammatory cell infiltrates; all had prolonged elevation of creatine kinase and all ultimately received biologic therapies.

Conclusion.

Anti-HMGCR in UK children with myositis are associated with severe disease that is poorly responsive to standard treatment.

Monitoring change in volume of calcifications in juvenile idiopathic inflammatory myopathy: a pilot study using low dose computed tomography

BACKGROUND

Dystrophic calcifications may occur in patients with J uvenile Idiopathic Inflammatory Myopathy (JIIM) as well as other connective tissue and metabolic diseases, but a reliable method of measuring the volume of these calcifications has not been established. The purpose of this study is to determine the feasibility of low dose, limited slice, Computed Tomography (CT) to measure objectively in-situ calcification volumes in patients with JIIM over time.

METHODS

Ten JIIM patients (eight JDM, two Overlap) with calcifications were prospectively recruited over a 2-year period to undergo two limited, low dose, four-slice CT scans. Calculation of the volume of calcifications used a CT post processing workstation. Additional patient data included: Disease Activity Scores (DAS), Childhood Myositis Assessment Scale (CMAS), myositis specific antibodies (MSA), and the TNFα-308 promoter region A/G polymorphism. Statistical analysis utilized the Pearson correlation coefficient, the paired t-test and descriptive statistics.

RESULTS

Ten JIIM, mean age 14.54 ± 4.54 years, had a duration of untreated disease of 8.68 ± 5.65 months  MSA status: U1RNP (1), PM-Scl (1), Ro (1, 4 indeterminate), p155/140 (2), MJ (3), Mi-2 indeterminate (1), negative (3). 4/8 JDM (50%) were TNF-α-308 A+. Overall, the calcification volumes tended to decrease from the first to the second CT study by 0.5 cm³ (from 2.79 ± 1.98 cm³ to 2.29 ± 2.25 cm³). The average effective radiation dose was 0.007 ± 0.002, 0.010 ± 0.005, and 0.245 mSv for the upper extremity, lower extremity and chest, respectively (compared to a standard chest x-ray-- 0.02mSV effective dosage).

CONCLUSION

We conclude: 1) the limited low dose CT technique provides objective data about volume of the calcifications in JIIM; 2) measuring the volume of calcifications in an extremity is associated with minimal radiation exposure; 3) This method may be useful to evaluate the efficacy of therapies for JIIM dystrophic calcification.

Muscle Biopsy Findings in Combination With Myositis-Specific Autoantibodies Aid Prediction of Outcomes in Juvenile Dermatomyositis

OBJECTIVE

Juvenile dermatomyositis (DM) is a rare and severe autoimmune condition characterized by rash and proximal muscle weakness. While some patients respond to standard treatment, others do not. This study was carried out to investigate whether histopathologic findings and myositis-specific autoantibodies (MSAs) have prognostic significance in juvenile DM.

METHODS

Muscle biopsy samples (n = 101) from patients in the UK Juvenile Dermatomyositis Cohort and Biomarker Study were stained, analyzed, and scored for severity of histopathologic features. In addition, autoantibodies were measured in the serum or plasma of patients (n = 90) and longitudinal clinical data were collected (median duration of follow-up 4.9 years). Long-term treatment status (on or off medication over time) was modeled using generalized estimating equations.

RESULTS

Muscle biopsy scores differed according to MSA subgroup. When the effects of MSA subgroup were accounted for, increased severity of muscle histopathologic features was predictive of an increased risk of remaining on treatment over time: for the global pathology score (histopathologist's visual analog scale [hVAS] score), 1.48-fold higher odds (95% confidence interval [95% CI] 1.12-1.96; P = 0.0058), and for the total biopsy score (determined with the standardized score tool), 1.10-fold higher odds (95% CI 1.01-1.21; P = 0.038). A protective effect was identified in patients with anti-Mi-2 autoantibodies, in whom the odds of remaining on treatment were 7.06-fold lower (95% CI 1.41-35.36; P = 0.018) despite muscle biopsy scores indicating more severe disease. In patients with anti-nuclear matrix protein 2 autoantibodies, anti-transcription intermediary factor 1γ autoantibodies, or no detectable autoantibody, increased histopathologic severity alone, without adjustment for the effect of MSA subtype, was predictive of the risk of remaining on treatment: for the hVAS global pathology score, 1.61-fold higher odds (95% CI 1.16-2.22; P = 0.004), and for the total biopsy score, 1.13-fold higher odds (95% CI 1.03-1.24; P = 0.013).

CONCLUSION

Histopathologic severity, in combination with MSA subtype, is predictive of the risk of remaining on treatment in patients with juvenile DM and may be useful for discussing probable treatment length with parents and patients. Understanding these associations may identify patients at greater risk of severe disease.

Comparison of the Utility and Validity of Three Scoring Tools to Measure Skin Involvement in Patients With Juvenile Dermatomyositis

Objective

To compare the abbreviated Cutaneous Assessment Tool (CAT), Disease Activity Score (DAS), and Myositis Intention to Treat Activity Index (MITAX) and correlate them with the physician's 10‐cm skin visual analog scale (VAS) in order to define which tool best assesses skin disease in patients with juvenile dermatomyositis.

Methods

A total of 71 patients recruited to the UK Juvenile Dermatomyositis Cohort and Biomarker Study were included and assessed for skin disease using the CAT, DAS, MITAX, and skin VAS. The Childhood Myositis Assessment Scale (CMAS), manual muscle testing of 8 groups (MMT8), muscle enzymes, inflammatory markers, and physician's global VAS were recorded. Relationships were evaluated using Spearman's correlations and predictors with linear regression. Interrater reliability was assessed using intraclass correlation coefficients.

Results

All 3 tools showed correlation with the physician's global VAS and skin VAS, with DAS skin showing the strongest correlation with skin VAS. DAS skin and CAT activity were inversely correlated with CMAS and MMT8, but these correlations were moderate. No correlations were found between the skin tools and inflammatory markers or muscle enzymes. DAS skin and CAT were the quickest to complete (mean ± SD 0.68 ± 0.1 minutes and 0.63 ± 0.1 minutes, respectively).

Conclusion

The 3 skin tools were quick and easy to use. The DAS skin correlated best with the skin VAS. The addition of CAT in a bivariate model containing the physician's global VAS was a statistically significant estimator of skin VAS score. We propose that there is scope for a new skin tool to be devised and tested, which takes into account the strengths of the 3 existing tools.