Developments in the classification and treatment of the juvenile idiopathic inflammatory myopathies

Familial clustering of dysbiotic oral and fecal microbiomes in juvenile dermatomyositis

Juvenile dermatomyositis (JDM) is a rare immune-mediated disease of childhood with putative links to microbial exposures. In this multi-center, prospective, observational cohort study, we evaluated whether JDM is associated with discrete oral and gut microbiome signatures. We generated 16S rRNA sequencing data from fecal, saliva, supragingival, and subgingival plaque samples from JDM probands (n = 28). To control for genetic and environmental determinants of microbiome community structure, we also profiled microbiomes of unaffected family members (n = 27 siblings, n = 26 mothers, and n = 17 fathers). Sample type (oral-vs-fecal) and nuclear family unit were the predominant variables explaining variance in microbiome diversity, more so than having a diagnosis of JDM. The oral and gut microbiomes of JDM probands were more similar to their own unaffected siblings than they were to the microbiomes of other JDM probands. In a sibling-paired within-family analysis, several potentially immunomodulatory bacterial taxa were differentially abundant in the microbiomes of JDM probands compared to their unaffected siblings, including Faecalibacterium (gut) and Streptococcus (oral cavity). While microbiome features of JDM are often shared by unaffected family members, the loss or gain of specific fecal and oral bacteria may play a role in disease pathogenesis or be secondary to immune dysfunction in susceptible individuals.

Autoantibodies Recognizing Specificity Protein 4 Co-occur With Anti-Transcription Intermediary Factor 1 and Are Associated With Distinct Clinical Features and Immunogenetic Risk Factors in Juvenile Myositis

OBJECTIVE

Autoantibodies recognizing specificity protein 4 (Sp4) were recently discovered in adults with idiopathic inflammatory myopathies (IIM). Anti-Sp4 autoantibodies co-occurred in patients with anti-transcription intermediary factor 1 (anti-TIF1) autoantibody-positive dermatomyositis (DM) and were associated with a reduced risk of cancer. In the present study, the prevalence and clinical features associated with anti-Sp4 autoantibodies in juvenile-onset IIM were investigated.

METHODS

Serum samples from 336 patients with juvenile myositis in a cross-sectional cohort and 91 healthy controls were screened for anti-Sp4 autoantibodies using enzyme-linked immunosorbent assay. Clinical characteristics, outcomes, and HLA alleles of those with and those without anti-Sp4 autoantibodies were compared.

RESULTS

Anti-Sp4 autoantibodies were present in 23 patients (7%) with juvenile myositis and were not present in any of the controls. Anti-Sp4 autoantibodies were found among each clinical myositis subgroup. The frequency of TIF1 autoantibody positivity was significantly higher among those with anti-Sp4 autoantibodies (21 [91%] versus 92 [30%], P < 0.001). In the anti-TIF1 autoantibody-positive subgroup, Raynaud's phenomenon (8 [38%] versus 2 [2%], P < 0.001) was more common and peak aspartate aminotransferase was significantly lower in those with anti-Sp4 autoantibodies. None of the patients with anti-Sp4 autoantibodies required a wheelchair. Among White patients, DQA1*04 and DRB1*08 were associated with anti-Sp4 autoantibodies.

CONCLUSION

Anti-Sp4 autoantibodies were found in patients with juvenile-onset IIM, predominantly those with coexisting anti-TIF1 autoantibodies. Patients with anti-Sp4 autoantibodies represent a phenotypic subset of anti-TIF1 autoantibody-positive myositis characterized by frequent Raynaud's phenomenon and less pronounced muscle involvement, similar to adults with these autoantibodies. Novel immunogenetic risk factors for White patients with IIM were identified among juveniles with anti-Sp4 autoantibodies.

Juvenile Dermatomyositis Without Skin Lesions in an Antinuclear Matrix Protein 2 Antibody Seropositive Pediatric Case

ABSTRACT

We report a 5-year-old boy who presented with progressive weakness in 4 limbs and gait disorders over 7 months. No skin rash was observed on admission. A symmetrical proximodistal weakness was found. The creatine kinase level was normal with a slightly elevated lactate dehydrogenase level. Biopsy specimens showed infiltration of mononuclear cells, few necrotic fibers, and perifascicular atrophy. Screening for myositis-specific antibodies was positive for the antinuclear matrix protein 2 antibody, which is mainly associated with dermatomyositis. Symptoms improved on receiving corticosteroids. Our findings suggest that in cases where inflammatory muscle disease is suspected, antinuclear matrix protein 2 antibody analyses should be considered for precise diagnosis, even with the absence of dermatological symptoms. The case suggests consideration of juvenile dermatomyositis in children with no associated skin manifestations or elevated creatine kinase levels and highlights the importance of screening for myositis-specific antibodies in helping with the diagnosis, given the possible heterogeneity of its clinical presentations.

Implementation of an embedded behavioral health care model in a pediatric rheumatology subspecialty juvenile myositis clinic

Youth with chronic medical illness, such as juvenile myositis (JM), require specialized behavioral health care. However, access to such care is challenging due to the youth mental health crisis, which impacts accessibility of mental health services in the community, as well as challenges accessing behavioral health care above and beyond the demands of care related to their JM management. In this paper we describe an embedded behavioral health care model, including the establishment and implementation of such a model, at a pediatric hospital where youth with JM receive medical care in a Center of Excellence (CoE). We describe a unique partnership with a philanthropic organization; the challenges and benefits of delivering care within this model; as well as recommendations for maximizing its effectiveness. Ultimately, we provide an example of a successful embedded behavioral health care program for youth with rare disease, which may be applied to other institutions providing similar care.

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.

Treatment escalation patterns to start biologics in refractory moderate juvenile dermatomyositis among members of the Childhood Arthritis and Rheumatology Research Alliance

BACKGROUND

Despite new and better treatments for juvenile dermatomyositis (JDM), not all patients with moderate severity disease respond adequately to first-line therapy. Those with refractory disease remain at higher risk for disease and glucocorticoid-related complications. Biologic disease-modifying antirheumatic drugs (DMARDs) have become part of the arsenal of treatments for JDM. However, prospective comparative studies of commonly used biologics are lacking.

METHODS

The Childhood Arthritis and Rheumatology Research Alliance (CARRA) JDM biologics workgroup met in 2019 and produced a survey assessing current treatment escalation practices for JDM, including preferences regarding use of biologic treatments. The cases and questions were developed using a consensus framework, requiring 80% agreement for consensus. The survey was completed online in 2020 by CARRA members interested in JDM. Survey results were analyzed among all respondents and according to years of experience. Chi-square or Fisher's exact test was used to compare the distribution of responses to each survey question.

RESULTS

One hundred twenty-one CARRA members responded to the survey (denominators vary for each question). Of the respondents, 88% were pediatric rheumatologists, 85% practiced in the United States, and 43% had over 10 years of experience. For a patient with moderately severe JDM refractory to methotrexate, glucocorticoids, and IVIG, approximately 80% of respondents indicated that they would initiate a biologic after failing 1-2 non-biologic DMARDs. Trials of methotrexate and mycophenolate were considered necessary by 96% and 60% of respondents, respectively, before initiating a biologic. By weighed average, rituximab was the preferred biologic over abatacept, tocilizumab, and infliximab. Over 50% of respondents would start a biologic by 4 months from diagnosis for patients with refractory moderately severe JDM. There were no notable differences in treatment practices between respondents by years of experience.

CONCLUSION

Most respondents favored starting a biologic earlier in disease course after trialing up to two conventional DMARDs, specifically including methotrexate. There was a clear preference for rituximab. However, there remains a dearth of prospective data comparing biologics in refractory JDM. These findings underscore the need for biologic consensus treatment plans (CTPs) for refractory JDM, which will ultimately facilitate comparative effectiveness studies and inform treatment practices.

Performance of the EULAR/ACR 2019 classification criteria for systemic lupus erythematous in monogenic lupus

OBJECTIVE

To evaluate the application of the EULAR/ACR-2019 criteria to monogenic lupus patients and compare its performance against the SLICC-2012 criteria.

METHODS

In a multicenter retrospective cohort study, consecutive patients with monogenic lupus from three tertiary lupus clinics were enrolled. The diagnosis of monogenic lupus was based on the expert physician's opinion or fulfilling the SLICC-2012 criteria. All enrolled patients had genetic variants. A control group of sporadic childhood SLE (cSLE) and non-SLE patients, were included. A descriptive data analysis was conducted, and the EULAR/ACR-2019 and SLICC-2012 criteria were applied to both groups.

RESULTS

Forty-nine patients with monogenic lupus with a median age at diagnosis of 6.0 (IQR 3.0-10.8) years and 104 controls (55 patients with cSLE and 49 non-lupus patients with a median age at diagnosis of 10.0 and 5.0 respectively) were included. Forty-four (89.8%) patients with monogenic lupus fulfilled the EULAR/ACR-2019 with a mean score of 22.3±8.9. The most frequent domains were immunologic (93.9%), musculoskeletal and renal (each 57.1%), and mucocutaneous (55.1%). Fifty-four (98.2%) cSLE patients and six (12.2%) non-lupus patients met the EULAR/ACR-2019 criteria with a mean score of 22.5±9.2 and 8.5±5.2, respectively. The sensitivity of the EULAR/ACR-2019 criteria in monogenic lupus was 89.9% (95% CI: 78.3-90.2), while the specificity was 87.6% (95% CI: 75.2-88.7).

CONCLUSION

This is the first and largest cohort of monogenic lupus patients testing the performance of the 2019-EULAR/ACR criteria. It efficiently classifies monogenic lupus patients, irrespective of the underlying genetic variants. Further studies are needed before these criteria are adopted worldwide. Key Points • Typically, patients with monogenic lupus have early onset severe disease, especially with mucocutaneous manifestations and a strong family history of SLE. • Monogenic lupus is a distinctive entity and might differ from the sporadic childhood SLE. • Our study includes a large multinational cohort of monogenic lupus with heterogeneous phenotypic features and underlying genetic variants. • Our study demonstrates that the EULAR/ACR-2019 criteria efficiently classified monogenic lupus patients, irrespective of the diversity of the underlying genetic variants.

Inflammatory myopathies in childhood

Myositis in childhood can occur under different conditions and with various aetiologies, juvenile dermatomyositis (jDM) being by far the most frequent entity. The exact diagnostic workup and precise assessment of muscular as well as extramuscular involvement of organs in these systemic autoimmune diseases are relevant for specific and adjunct treatment of complications. Many new insights have become available with respect to the pathophysiological concepts as well as modern diagnostic measures and therapeutic approaches. Autoantibody detection in the serum of children with myositis is one of the major novelties that has become widely used and that is indeed helpful for diagnostic and prognostic measures. The pathophysiological relevance of type I interferons in jDM has been studied intensively in the past years. jDM is now seen as an acquired interferonopathy and first therapeutic consequences have been drawn from this pathogenic finding with the use of Janus-kinase inhibitors for severe and not otherwise treatable children.

Respiratory symptoms as initial manifestations of interstitial lung disease in clinically amyopathic juvenile dermatomyositis: a case report with literature review

Background

Clinically amyopathic juvenile dermatomyositis (CAJDM) is a clinical subgroup of juvenile dermatomyositis (JDM), characterized by JDM rashes with little or no clinically evident muscle weakness. Interstitial lung disease (ILD) is an uncommon but potentially fatal complication of juvenile dermatomyositis (JDM). While adults with dermatomyositis-associated ILD usually present respiratory symptoms before or at the same time as skin muscle manifestations, only a few studies have covered the onset of respiratory symptoms of ILD in JDM patients, especially CAJDM. There is currently no clear effective treatment regime or any prognostic factors for CAJDM-associated ILD.

Case presentation

Here, we report the first case of a CAJDM patient who presented with respiratory symptoms as the initial manifestation. A 10-year-old male patient presented to the hospital with a complaint of progressive cough and chest pain. Violaceous macule and papules appeared a few days later and he was positive for anti-Ro-52 antibodies. Imaging showed diffuse interstitial infiltration in both lungs and lung function tests showed restrictive and obstructive ventilatory dysfunction. Muscular abnormalities were excluded by thigh magnetic resonance imaging (MRI) and electromyography. Skin biopsy showed pathognomonic findings consistent with DM. Lung biopsy indicated chronic inflammation of the mucosa. This patient was finally diagnosed with CAJDM complicated by ILD and prescribed methylprednisolone, immunoglobulin, prednisolone and mycophenolate mofetil (MMF) for treatment. The patient’s cutaneous and respiratory manifestations were largely improved. We retrospectively reviewed this and another six cases with CAJDM-associated ILD reported previously to better understand its clinical characteristics and effective management.

Conclusions

Initial respiratory symptoms with rapid progression in patients presenting Gottron papules should be considered manifestations of CAJDM-associated ILD. We also found a combination of corticosteroids, IVIG and MMF to be an effective method of arresting the progress of CAJDM-associated ILD and improving the prognosis of the patients.

Updates on Juvenile Dermatomyositis from the Last Decade: Classification to Outcomes

Juvenile dermatomyositis (JDM) is a heterogeneous disease with new classification criteria and updates in myositis-specific autoantibody and myositis-associated antibody groups. There are many validated assessment tools for assessing disease activity in JDM. Future studies will optimize these tools and improve feasibility in clinical and research contexts. Genetic and environmental risk factors, mechanisms of muscle pathology, role of interferon, vascular markers, and changes in immune cells provide insights to JDM pathogenesis. Outcomes have improved, but chronic disease, damage, and mortality highlight the need for better outcome predictors and treatments. Increased collaboration of stakeholders may help overcome research barriers and improve JDM treatment.

Atypical Power Doppler Ultrasound Findings in Juvenile Idiopathic Inflammatory Myositis (JIIM) Flare

Juvenile idiopathic inflammatory myositis (JIIM) is a multisystem inflammatory disease that impacts the muscles, skin, and blood vessels. Gray-scale power Doppler ultrasound is a technique that can be used to assist the diagnosis of JIIM and myositis in general. We report a case of an atypical symptomatic JIIM myositis flare that shows increased muscle echogenicity without the corresponding increase (complete absence) of Doppler flow.

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.

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.

Long-term outcomes in Juvenile Myositis patients

OBJECTIVE

Juvenile idiopathic inflammatory myopathies (JIIM) are rare, chronic autoimmune muscle diseases of childhood, with the potential for significant morbidity. Data on long-term outcomes is limited. In this study we investigate correlations between clinical and demographic features with long-term outcomes in a referral population of adult patients with JIIM.

METHODS

Forty-nine adults with JIIM were assessed at two referral centers between 1994 and 2016. Features of active disease and damage at a cross-sectional assessment were obtained. Regression modeling was used to examine factors associated with long-term outcomes, defined by the presence of calcinosis or a higher adjusted Myositis Damage Index (MDI) score. A multivariable model of MDI was constructed using factors that were statistically significant in bivariate models.

RESULTS

At a median of 11.5 [IQR 4.5-18.9] years following diagnosis, median American College of Rheumatology (ACR) functional class was 2 [1.5-3.0], Health Assessment Questionnaire (HAQ) score was 0.4 out of 3.0 [0.0-1.0], and manual muscle testing (MMT) score was 229 out of 260 [212.6-256.8]. Median MDI score was 6.0 [3.5-8.9], with the most commonly damaged organ systems being cutaneous and musculoskeletal. Factors associated with an elevated MDI score were the presence of erythroderma and other cutaneous manifestations, disease duration, and ACR functional class. Calcinosis was present in 55% of patients. The strongest predictors of calcinosis were disease duration, periungual capillary changes, and younger age at diagnosis.

CONCLUSION

In a tertiary referral population, long-term functional outcomes of JIIM are generally favorable, with HAQ scores indicative of mild disability. Although most patients had mild disease activity and virtually all had significant disease damage, severe or systemic damage was rare. Certain clinical features are associated with long-term damage and calcinosis.

Outcome of children with systemic rheumatic diseases admitted to pediatric intensive care unit: An experience of a tertiary hospital

Objective

To report the outcome of children with rheumatic diseases admitted to pediatric intensive care unit (PICU) in a tertiary hospital.

Methods

Database from PICU and pediatric rheumatology section used to retrieve all candidate patients admitted to PICU from June 2000 to December 2017. Medical records of all enrolled patients reviewed for diagnosis, organ involvement, reason of PICU admission, the length of stay, and outcome.

Results

Twenty-five patients (17 female, 8 male) with total of 41 admissions identified. The median PICU stay was 13.5 days (range, 3–24). The most frequent diagnoses were systemic lupus erythematosus (SLE) (48%), followed by systemic vasculitis (16%). Most admissions were from the medical ward (68.3%), while 24.4% from the emergency room. The main reason of PICU admission was a disease flare or related complications (48.8%), followed by infection (34.2%). Fifty one percent of the admissions were due to respiratory dysfunction, 46% required non-invasive respiratory support while 38% was in need for mechanical ventilation. During PICU stay, anti-microbial agents used 90.3%, immunosuppressive treatment adjustment 75.6%, anti-hypertensive 24.4% and vasopressors 12.2%. Twelve patients (48%) fully recovered and 40% partially recovered while three patients died during their PICU stay. The causes of death were macrophage activation syndrome complicated by sepsis in two patients and advanced pulmonary hypertension in one patient.

Conclusion

Our data showed that children with rheumatic diseases, particularly SLE, are mostly admitted to PICU with serious disease exacerbation or severe infection. To improve the outcome, early diagnosis of critical condition and proper intervention are fundamental in reducing mortality.

Factors Associated With Clinical Remission of Skin Disease in Dermatomyositis

Importance

Cutaneous disease represents a significant burden for patients with dermatomyositis. However, quantitative estimates of the probability of skin disease remission and clinical factors associated with skin outcomes are lacking.

Objective

To characterize cutaneous disease course in adult patients with dermatomyositis.

Design, Setting, and Participants

Prospective cohort study conducted at a dermatology clinic at a tertiary academic referral center. All adult patients with dermatomyositis (age >18 years) seen between May 15, 2007, and October 28, 2016, were eligible. Patients were included in the current analysis if they had a baseline Cutaneous Dermatomyositis Disease Area and Severity Index (CDASI) activity score of 12 or higher, and 2 or more CDASI scores separated by 3 months or more within their first 3 years of follow-up.

Main Outcomes and Measures

The percentage of patients who achieved clinical remission of their cutaneous disease as measured by the CDASI over a 3-year follow-up.

Results

A total of 74 patients met our inclusion criteria (mean [SD] age at initial CDASI scoring, 54 [13] years; 58 women [78%]), and 28 (38%) achieved clinical remission during our 3-year follow-up period. Increased age (odds ratio [OR], 1.07; 95% CI, 1.02-1.12; P = .01), a dermatomyositis-associated malignancy (OR, 14.46; 95% CI, 2.18-96.07; P = .01), and treatment with mycophenolate mofetil (OR, 6.00; 95% CI, 1.66-21.78; P = .01) were significantly associated with clinical remission of skin disease in multivariable analysis. Patients with anti-melanoma differentiation-associated protein 5 antibodies had a significantly lower probability of meeting outcome criteria in our time-to-event analysis. Baseline cutaneous disease activity, disease duration at baseline, and disease duration before first systemic therapy were not significantly associated with clinical remission of skin disease.

Conclusions and Relevance

Clinical remission was relatively uncommon in our population despite aggressive systemic therapy, and patients with anti-melanoma differentiation-associated protein 5 antibodies were even less likely to enter clinical remission during a 3-year follow-up period. Although mycophenolate mofetil compared favorably with other treatment options, our data provide evidence that a substantial population of patients with dermatomyositis have skin disease that is not adequately managed with standard-of-care therapies.

Disease Specific Autoantibodies in Idiopathic Inflammatory Myopathies

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

Medications received by patients with juvenile dermatomyositis

OBJECTIVE

Few controlled studies are available to guide treatment decisions in juvenile dermatomyositis (JDM). This study evaluated therapies received, changes of treatment over time, and factors associated with medication choices in JDM.

METHODS

We performed a retrospective analysis of the number and type of therapies and duration of treatment for 320 patients with JDM enrolled in a North American registry. Kaplan-Meier and logistic regression analysis were used to assess the association of demographic and clinical features and autoantibodies with medication usage.

RESULTS

High-dose oral prednisone was the primary therapy given to 99% of patients. 1997 was determined to be a threshold year for increasing usage of medications other than prednisone. The median time to half the initial oral prednisone dose was shorter in patients diagnosed after vs. before 1997 (10 vs. 19 months, P < 0.01). Patients received intravenous methylprednisolone (IVMP), methotrexate, intravenous immunoglobulin, antimalarial drugs, and combination therapy more frequently when diagnosed after 1997. IVMP was frequently received by patients with severe illness onset, anti-p155/140 (anti-TIF1) and anti-MJ (anti-NXP2) autoantibodies. Treatment with methotrexate was associated with older age at diagnosis and anti-MJ autoantibodies, while antimalarial therapy was associated with anti-p155/140 autoantibodies and mild onset severity.

CONCLUSION

Oral prednisone has been the mainstay of therapy in JDM, and prednisone was reduced faster in patients diagnosed after 1997 when there was also an increase in other medications. Specific medications received by patients with JDM correlated with year and age at diagnosis, myositis autoantibodies, onset severity, and illness features.

Clinical signs and symptoms in a joint model of four disease activity parameters in juvenile dermatomyositis: a prospective, longitudinal, multicenter cohort study

Background

It is currently impossible to predict the prognosis of patients with juvenile dermatomyositis (JDM). The aim of this study was to find clinical features most strongly associated with outcome variables in JDM as a first step towards tailor-made treatment.

Methods

In a large, prospectively followed, multicenter cohort study of 340 patients with JDM, each contributing multiple visits, a Bayesian model of disease activity was developed, using the four continuous outcome variables creatine kinase (CK), childhood myositis assessment score (CMAS), manual muscle testing of 8 muscle groups (MMT8) and the physician’s global assessment of disease activity (PGA). Covariates were clinical signs and symptoms. Correlations among visits of the same patient were resolved by introducing subject-specific random effects.

Results

Myalgia and dysphonia were associated with worse disease activity according to all outcome variables. Periorbital rash, rash on the trunk, rash over large joints, nail fold changes and facial swelling were associated with higher PGA. Notably, periorbital rash was also associated with higher CK and lower CMAS and nail fold changes with lower CMAS. Contractures were associated with lower CMAS and MMT8 and higher PGA. Patients with higher CMAS exhibited a higher MMT8 as well. PGA had the highest probability among the four outcome variables of being abnormal even if the other three outcome variables were normal.

Conclusions

The signs and symptoms associated with disease activity could be used to stratify patients and adapt treatment plans to disease activity. The correlation between CMAS and MMT8 and the unique information captured by PGA implied that PGA should be maintained as an outcome variable, whereas CMAS and MMT8 might be simplified.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1687-8) contains supplementary material, which is available to authorized users.

Effect of Adalimumab on Refractory Arthritis in Juvenile Idiopathic Inflammatory Myopathy with Anti-MDA5 Autoantibody

A 10-year-old girl manifested persistent fever, skin rash, leg pain, fatigue, and joint pain. Based on muscle weakness, elevated muscle-derived enzymes, magnetic resonance imaging, and skin biopsy results, the diagnosis was juvenile idiopathic inflammatory myopathies (JIIM). Chest CT was normal; the anti-melanoma differentiation-associated protein-5 (anti-MDA5) autoantibody was positive. Initial manifestations subsided after prednisolone (PSL) and methotrexate treatment. After the PSL dosage was decreased, the patient presented with metacarpophalangeal (MCP) joint pain and swelling in both index fingers, synovial fluid, and signals on power Doppler ultrasound. The arthritis was refractory to cyclosporine and tacrolimus. Radiography showed progressive MCP joint space narrowing and joint erosion. Adalimumab was initiated 14 months after disease onset. There was a mildly increased matrix metalloproteinase-3 (MMP3) level, an erythrocyte sedimentation ratio (ESR), and a normal CRP level. Adalimumab resulted in decreased MCP joint pain and swelling. PSL was discontinued 10 months after adalimumab initiation; after 9 more months of adalimumab, there were no significant ultrasonography findings. MMP3 and ESR levels normalized during treatment. Radiography after 2 years of adalimumab showed further progressive MCP joint space narrowing restricting dorsiflexion. This report clarified that anti-MDA5-positive JIIM joint manifestations were due to active synovitis and that adalimumab is required for severe cases. Further experience is needed to determine the pathology, severity, and prognosis of this type of arthritis.

Trajectories of cardiorespiratory fitness in patients with juvenile dermatomyositis

Objectives

Previous research demonstrated decreased cardiorespiratory fitness (CRF) in patients with JDM during active disease and remission. However, longitudinal data regarding trajectories of CRF are currently lacking. The objective of this study was to determine trajectories of CRF in patients with both monocyclic and chronic JDM, and to identify potential predictors of these trajectories.

Methods

Thirty-six patients with JDM [median age (interquartile range) at diagnosis: 8.3 (6.3-15.4) years] treated in our paediatric rheumatology outpatient clinic were included. All patients performed multiple cardiopulmonary exercise tests between 2003 and 2016. Relevant CRF parameters were analysed, including peak oxygen uptake, maximal workload, mechanical efficacy and oxygen uptake at ventilatory anaerobic threshold. We analysed trajectories up to 10 years after diagnosis and determined predictors of CRF outcome parameters by multilevel analyses.

Results

Trajectories demonstrated significant declines in CRF during the active phase of the disease with subsequent improvement in CRF during the initial years after diagnosis. However, hereafter no further improvements, and even a decrease, in CRF were observed over time in both monocyclic and chronic subtypes of JDM. We found that a longer disease duration, younger age of onset and higher prednisone dose negatively influence CRF.

Conclusion

Patients with both monocyclic and chronic JDM show decreases in long-term CRF trajectories. Longer disease duration, younger age of onset and higher prednisone dose negatively influence CRF. This study stresses the need for regular evaluation of CRF and implementation of (exercise) interventions to improve CRF in patients with JDM, even in monocyclic patients.

Decreased CD3-CD16+CD56+ natural killer cell counts in children with orbital myositis: a clue to disease activity

The study aimed to document the utility of the absolute number of natural killer cells as a biomarker in paediatric orbital myositis (OM). Extracted data from four children with OM included demographics, laboratory values, imaging and treatment response. Stored sera (−80°C) were tested for IgG4 levels in three cases and antibody to Coxsackie B in two cases. Their first symptom was at 14.4±1.2 years (mean±SD). At diagnosis three had creatine phosphokinase (CPK) of 97.3±44.2, aldolase of 8.5±2.8 (n=2), alanine aminotransferase (ALT) of 13±2.8 (n=2) and aspartate aminotransferase (AST) of 21.3±2.9. IG4 level was 87.7±66 (normal=8–89 mg/dL); two sera (patients 1and4) were positive (>1:8 dilution) for anti-Coxsackievirus antigen B5. The CD3-CD16+CD56+ natural killer absolute count was 96.7±28.7 (lower limit of normal=138), increasing to 163±57.2 with disease resolution in three patients. The fourth patient was followed elsewhere. CT showed involvement of bilateral superior oblique, lateral rectus or the left medial rectus muscles. Treatment included intravenous methylprednisolone, methotrexate (n=2) and other immunosuppressants. Paediatric OM disease activity was associated with initially low absolute CD3-CD16+CD56+ natural killer cell counts, which normalised with improvement. We speculate (1) infection, such as Coxsackie B virus, may be associated with paediatric OM; and (2) the absolute count of circulating CD3-CD16+CD56+ natural killer lymphocytes may serve as a biomarker to guide medical therapy.

Idiopathic inflammatory myopathies - a guide to subtypes, diagnostic approach and treatment

The idiopathic inflammatory myopathies are a group of conditions characterised by inflammation of muscles (myositis) and other body systems. The diagnosis can be challenging because of the many potential clinical features and extra-muscular manifestations, which may be seemingly unrelated. An accurate diagnosis requires up-to-date understanding of the clinical manifestations, different clinical subtypes and appropriate interpretation of investigations, including newly described serological subtypes.This review will detail the approach to the diagnosis of an idiopathic inflammatory myopathy, based on up-to-date knowledge. The recently updated classification criteria and treatment options will also be described.

Modelling disease activity in juvenile dermatomyositis: A Bayesian approach

Juvenile dermatomyositis is the most common form of the juvenile idiopathic inflammatory myopathies characterised by muscle and skin inflammation, leading to symmetric proximal muscle weakness and cutaneous symptoms. It has a fluctuating course and varying prognosis. In a Bayesian framework, we develop a joint model for four longitudinal outcomes, which accounts for within individual variability as well as inter-individual variability. Correlations among the outcome variables are introduced through a subject-specific random effect. Moreover, we exploit an approach similar to a hurdle model to account for excess of a specific outcome in the response. Clinical markers and symptoms are used as covariates in a regression set-up. Data from an ongoing observational cohort study are available, providing information on 340 subjects, who contributed 2725 clinical visits. The model shows good performance and yields efficient estimations of model parameters, as well as accurate predictions of the disease activity parameters, corresponding well to observed clinical patterns over time. The posterior distribution of the by-subject random intercepts shows a substantial correlation between two of the outcome variables. A subset of clinical markers and symptoms are identified as associated with disease activity. These findings have the potential to influence clinical practice as they can be used to stratify patients according to their prognosis and guide treatment decisions, as well as contribute to on-going research about the most relevant outcome markers for patients affected by juvenile dermatomyositis.

Muscle MRI at the time of questionable disease flares in Juvenile Dermatomyositis (JDM)

BACKGROUND

The course of JDM has improved substantially over the last 70 years with early and aggressive treatments. Yet it remains difficult to detect disease flares as symptoms may be mild; signs of rash and muscle weakness vary widely and are often equivocal; laboratory tests of muscle enzyme levels are often normal; electromyography and muscle biopsy are invasive. Alternative tools are needed to help decide if more aggressive treatment is needed. Our objective is to determine the effectiveness of muscle Magnetic Resonance Imaging (MRI) in detecting JDM flares, and how an MRI affects physician's decision-making regarding treatment.

METHODS

This study was approved by the Institutional Review Board of Nationwide Children's Hospital. JDM patients were consulted between 1/2005 and 6/2015. MRIs were performed on both lower extremities without contrast sequentially: axial T1, axial T2 fat saturation, axial and coronal inversion recovery, and axial diffusion weighted. The physician decision that a JDM patient was in a flare was considered the gold standard. MRI results were compared with physician's decisions on whether a relapse had occurred, and if there was a concordance between the assessment methods.

RESULTS

Forty-five JDM patients were studied. Eighty percent had weakness at diagnosis, 100% typical rash, and 73% typical nail-fold capillary changes. At diagnosis, muscle enzymes were compatible with JDM generally (CK 52%, LDH 62%, aldolase 72%, AST 54% abnormal). EMG was abnormal in 3/8, muscle biopsy typical of JDM in 10/11, and MRI abnormal demonstrating myositis in 31/40. Thirteen patients had a repeat MRI for possible flares with differing indications. Three repeat MRI's were abnormal, demonstrating myositis. There was moderate agreement about flares between MRI findings and physician's treatment decisions (kappa = 0.59). In each abnormal MRI case the physician decided to increase treatment (100% probability for flares). MRI was negative for myositis in 10 patients, by which 7/10 the physicians chose to continue or to taper the medications (70% probability for non-flares).

CONCLUSION

A muscle MRI would facilitate objective assessments of JDM flares. When an MRI shows myositis, physicians tend to treat 100% of the time. When an MRI shows no myositis, physicians continued the same medications or tapered medications 70% of the time. Further studies would help confirm the utility and cost-effectiveness of MRI to determine JDM flares.

Autoantibodies in children with juvenile dermatomyositis: A single centre experience from North-West India

The objective of this study is to determine autoantibody profile in children with juvenile dermatomyositis (JDM). Children who were diagnosed with JDM (either recently diagnosed during the study period or follow-up patients) were included in the study. Autoantibodies were detected with commercially available Immunodot kit. Thirty patients were included in the study. Nine out of thirty patients (30%) were positive for one of the 12 autoantibodies tested. Anti-SRP antibody was most common antibody detected in 3 patients followed by anti-MDA-5 antibody in 2 patients; while anti-Jo1 antibody, anti-TIF1-γ antibody, anti-Mi-2 antibody, and anti-PM-Scl antibody were positive in 1 patient each. A different disease phenotype was observed with each autoantibody. The patient with anti-Jo1 antibody had a severe systemic disease in the form of interstitial lung disease; patients with anti-MDA-5 antibody and anti-Mi2 antibody had more severe skin disease with mild muscle disease and patients with anti-SRP antibody had significant skin and muscle disease. Anti-TIF1-γ and anti-PM-Scl antibodies were seen in patients with features of overlap syndrome (myositis-scleroderma). Estimation of autoantibodies may serve as an adjunct tool in delineating and defining distinct clinical phenotypes in children diagnosed with juvenile dermatomyositis. They may also help in prognostication.

Characteristics and outcome of children with juvenile dermatomyositis in Cape Town: a cross-sectional study

BACKGROUND

Juvenile dermatomyositis (JDM) is a rare idiopathic inflammatory childhood myopathy of uncertain aetiology. The demographic and clinical presentation of JDM may differ by race and geographic regions. Few studies have described the characteristics of JDM patients from Africa.

METHODS

We conducted a retrospective observational study to determine clinical characteristics and outcomes of patients satisfying the Bohan and Peter criteria for probable JDM seen between 2004 and 2013 in three hospitals in Cape Town, South Africa.

RESULTS

Twenty five cases were identified: 16 female and 9 male; thirteen (52 %) were of indigenous African, eleven (44 %) mixed and one (4 %) European ancestry. The median ages at disease onset and diagnosis were 6.75 (range 2.0-9.7) and 7.9 (range 3.4-9.75) years respectively. Eleven patients had calcinosis while the mortality was 2/25 (8 %). Only 40 % of the patients had clinically inactive disease by PRINTO criteria (modified) at last review. There was no statistically significant difference in racial distribution (p-value = 1), age at disease onset (p-value = 0.87) and disease duration prior to treatment initiation (p-value = 0.75) between patients who had clinically active and inactive disease.

CONCLUSION

The demographic characteristics of children with JDM were similar to that from most other regions of the world with female predominance and similar age at onset. Majority of the patients remained with clinically active disease, which put them at risk of further disease complications. Long term follow up and use of appropriate treatment guidelines may be indicated in management of JDM patients for optimum treatment outcomes.

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.

Congenital muscular dystrophy with inflammation: Diagnostic considerations

Background and Purpose:

Muscle biopsy features of congenital muscular dystrophies (CMD) vary from usual dystrophic picture to normal or nonspecific myopathic picture or prominent fibrosis or striking inflammatory infiltrate, which may lead to diagnostic errors. A series of patients of CMD with significant inflammatory infiltrates on muscle biopsy were correlated with laminin α2 deficiency on immunohistochemistry (IHC).

Material and Methods:

Cryostat sections of muscle biopsies from the patients diagnosed as CMD on clinical and muscle biopsy features from 1996 to 2014 were reviewed with hematoxylin and eosin(H&E), enzyme and immunohistochemistry (IHC) with laminin α2. Muscle biopsies with inflammatory infiltrate were correlated with laminin α2 deficiency.

Results:

There were 65 patients of CMD, with inflammation on muscle biopsy in 16. IHC with laminin α2 was available in nine patients, of which six showed complete absence along sarcolemma (five presented with floppy infant syndrome and one with delayed motor milestones) and three showed discontinuous, and less intense staining.

Conclusions:

CMD show variable degrees of inflammation on muscle biopsy. A diagnosis of laminin α2 deficient CMD should be considered in patients of muscular dystrophy with inflammation, in children with hypotonia/delayed motor milestones.

Using proteomic and genomic methods to understand JDM

Juvenile dermatomyositis is a complex illness characterized by vascular/perivascular inflammation, primarily in the skin and muscles. In this review, we discuss how proteomic and genomic technologies have expanded our understanding of the immune pathogenesis of this disease. We will also discuss further directions that the field may take to use existing and developing technologies to further our understanding of this often-perplexing disease.

Brief Report: Association of Myositis Autoantibodies, Clinical Features, and Environmental Exposures at Illness Onset With Disease Course in Juvenile Myositis

OBJECTIVE

To identify early factors associated with disease course in patients with juvenile idiopathic inflammatory myopathies (IIMs).

METHODS

Univariable and multivariable multinomial logistic regression analyses were performed in a large juvenile IIM registry (n = 365) and included demographic characteristics, early clinical features, serum muscle enzyme levels, myositis autoantibodies, environmental exposures, and immunogenetic polymorphisms.

RESULTS

Multivariable associations with chronic or polycyclic courses compared to a monocyclic course included myositis-specific autoantibodies (multinomial odds ratio [OR] 4.2 and 2.8, respectively), myositis-associated autoantibodies (multinomial OR 4.8 and 3.5), and a documented infection within 6 months of illness onset (multinomial OR 2.5 and 4.7). A higher overall clinical symptom score at diagnosis was associated with chronic or monocyclic courses compared to a polycyclic course. Furthermore, severe illness onset was associated with a chronic course compared to monocyclic or polycyclic courses (multinomial OR 2.1 and 2.6, respectively), while anti-p155/140 autoantibodies were associated with chronic or polycyclic courses compared to a monocyclic course (multinomial OR 3.9 and 2.3, respectively). Additional univariable associations of a chronic course compared to a monocyclic course included photosensitivity, V-sign or shawl sign rashes, and cuticular overgrowth (OR 2.2-3.2). The mean ultraviolet index and highest ultraviolet index in the month before diagnosis were associated with a chronic course compared to a polycyclic course in boys (OR 1.5 and 1.3), while residing in the Northwest was less frequently associated with a chronic course (OR 0.2).

CONCLUSION

Our findings indicate that myositis autoantibodies, in particular anti-p155/140, and a number of early clinical features and environmental exposures are associated with a chronic course in patients with juvenile IIM. These findings suggest that early factors, which are associated with poorer outcomes in juvenile IIM, can be identified.

Treatment of muscle weakness in neuromuscular disorders

INTRODUCTION

Weakness is one of the predominant clinical manifestations of neuromuscular disorders (NMDs), which strongly influences daily life, prognosis, and outcome of affected patients. One of the major therapeutic goals in NMD-patients is to completely resolve muscle weakness. Various treatment options are available and include physical therapy, electrotherapy, diet, drugs, avoidance or withdrawal of muscle-toxic and weakness-inducing agents, detoxification, stem-cell-therapy, plasma-exchange, respiratory therapy, or surgery. Most accessible to treatment is weakness from immune-mediated neuropathies, immune-mediated transmission-disorders, and idiopathic immune myopathies. Areas covered: This manuscript aims to summarize and discuss recent findings and future perspectives concerning the treatment of muscle weakness in NMDs. Data were obtained by a literature search in databases such as PubMed and Current-Contents. Expert commentary: Weakness is most easily treatable in acquired NMDs and in hereditary myopathies and neuropathies beneficial treatment options are also available. Research needs to be encouraged and intensified to further expand the spectrum of treatment options for weakness.

Physical exercise as a treatment for adult and juvenile myositis

There is growing evidence to support the safety and efficacy of exercise in patients with adult and juvenile idiopathic inflammatory myopathies. Five randomized controlled trials including adult patients with polymyositis and dermatomyositis (DM) and additional open studies have demonstrated reduced impairment and activity limitation as well as improved quality of life. In addition, recent studies have shown reduced disease activity assessed by consensus disease activity measures and reduced expression of genes regulating inflammation and fibrosis. Furthermore, exercise could improve muscle aerobic capacity as shown by increased mitochondrial enzyme activity. These data suggest that intensive aerobic exercise and resistance training could reduce disease activity and inflammation and improve muscle metabolism. Encouraging results have been reported from available open studies including patients with inclusion body myositis (IBM) and juvenile DM, indicating reduced impairment, activity limitation and improved quality of life also in these patients. Larger studies are needed to increase understanding of the effects of exercise in patients with active, recent-onset polymyositis and DM as well as in patients with IBM and juvenile DM.

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

The aim of this review was to summarize recent advances in the understanding of the clinical and autoantibody phenotypes, their associated outcomes and the pathogenesis of the juvenile idiopathic inflammatory myopathies (JIIMs). The major clinical and autoantibody phenotypes in children have many features similar to those in adults, and each has distinct demographic and clinical features and associated outcomes. The most common myositis autoantibodies in JIIM patients are anti-p155/140, anti-MJ and anti-MDA5. Higher mortality has been associated with overlap myositis as well as with the presence of anti-synthetase and anti-MDA5 autoantibodies; a chronic illness course and lipodystrophy have been associated with anti-p155/140 autoantibodies; and calcinosis has been associated with anti-MJ autoantibodies. Histologic abnormalities of JIIMs detectable on muscle biopsy have also been correlated with myositis-specific autoantibodies; for example, patients with anti-MDA5 show low levels of inflammatory infiltrate and muscle damage on biopsy. The first genome-wide association study of adult and juvenile dermatomyositis revealed three novel genetic associations, BLK, PLCL1 and CCL21 and confirmed that the human leucocyte antigen region is the primary risk region for juvenile dermatomyositis. Here, we review the well-established pathogenic processes in JIIMs, including the type 1 interferon and endoplasmic reticulum stress pathways. Several novel JIIM-associated inflammatory mediators, such as the innate immune system proteins, myeloid-related peptide 8/14, galectin 9 and eotaxin, have emerged as promising biomarkers of disease. Advances in our understanding of the phenotypes and pathophysiology of the JIIMs are leading to better tools to help clinicians stratify and treat these heterogeneous disorders.

Differential roles of hypoxia and innate immunity in juvenile and adult dermatomyositis

Dermatomyositis (DM) can occur in both adults and juveniles with considerable clinical differences. The links between immune-mediated mechanisms and vasculopathy with respect to development of perifascicular pathology are incompletely understood. We investigated skeletal muscle from newly diagnosed, treatment-naïve juvenile (jDM) and adult dermatomyositis (aDM) patients focusing on hypoxia-related pathomechanisms, vessel pathology, and immune mechanisms especially in the perifascicular region. Therefore, we assessed the skeletal muscle biopsies from 21 aDM, and 15 jDM patients by immunohistochemistry and electron microscopy. Transcriptional analyses of genes involved in hypoxia, as well as in innate and adaptive immunity were performed by quantitative Polymerase chain reaction (qPCR) of whole tissue cross sections including perifascicular muscle fibers.Through these analysis, we found that basic features of DM, like perifascicular atrophy and inflammatory infiltrates, were present at similar levels in jDM and aDM patients. However, jDM was characterized by predominantly hypoxia-driven pathology in perifascicular small fibers and by macrophages expressing markers of hypoxia. A more pronounced regional loss of capillaries, but no relevant activation of type-1 Interferon (IFN)-associated pathways was noted. Conversely, in aDM, IFN-related genes were expressed at significantly elevated levels, and Interferon-stimulated gene (ISG)15 was strongly positive in small perifascicular fibers whereas hypoxia-related mechanisms did not play a significant role.In our study we could provide new molecular data suggesting a conspicuous pathophysiological 'dichotomy' between jDM and aDM: In jDM, perifascicular atrophy is tightly linked to hypoxia-related pathology, and poorly to innate immunity. In aDM, perifascicular atrophy is prominently associated with molecules driving innate immunity, while hypoxia-related mechanisms seem to be less relevant.

Juvenile Idiopathic Inflammatory Myopathy in a Patient With Dyskeratosis Congenita Due to C16orf57 Mutation

Dyskeratosis congenita (DC) is a rare inherited disorder characterized by reticular skin pigmentation, oral cavity leukoplakia, and nail dystrophy. A variety of noncutaneous (dental, pulmonary, gastrointestinal, neurological, genitourinary, ophthalmic, and skeletal) abnormalities also have been reported. An 8-year-old boy with DC developed juvenile idiopathic inflammatory myopathy. C16orf57 mutation was identified as a genetic cause of DC. Treatment with methylprednisolone was initiated, followed with methotrexate, prednisolone, and high-dose intravenous immunoglobulin treatment. This is the first report on a patient with juvenile idiopathic inflammatory myopathy and DC.