Analysis of Published Criteria for Clinically Inactive Disease in a Large Juvenile Dermatomyositis Cohort Shows That Skin Disease Is Underestimated

Objective

The Pediatric Rheumatology International Trials Organisation (PRINTO) recently published criteria for classification of patients with juvenile dermatomyositis (DM) as having clinically inactive disease. The criteria require that at least 3 of 4 conditions be met, i.e., creatine kinase level ≤150 units/liter, Childhood Myositis Assessment Scale score ≥48, Manual Muscle Testing in 8 muscles score ≥78, and physician's global assessment of overall disease activity (PGA) ≤0.2. The present study was undertaken to test these criteria in a UK cohort of patients with juvenile DM.

Methods

We assessed 1,114 patient visits for the 4 items in the PRINTO criteria for clinically inactive disease. Each visit was analyzed to determine whether skin disease was present. The Disease Activity Score (DAS) for juvenile DM was determined in 59 patients.

Results

At 307 of the 1,114 visits, clinically inactive disease was achieved based on the 3 muscle criteria (but with a PGA of >0.2); rash was present at 65.8% of these visits and nailfold capillary abnormalities at 35.2%. When PGA ≤0.2 was one of the 3 criteria that were met, the frequency of skin signs was significantly lower (rash in 23.1% and nailfold capillary abnormalities in 8.7%). If PGA was considered an essential criterion for clinically inactive disease (P‐CID), patients with active skin disease were less likely to be categorized as having clinically inactive disease (a median DAS skin score of 0 [of a possible maximum of 9] in visits where the PGA was ≤0.2, versus a median DAS skin score of 4 in patients meeting the 3 muscle criteria [with a PGA of >0.2]; P < 0.001). Use of the P‐CID led to improvements in the positive predictive value and the positive likelihood ratio (85.4% and 11.0, respectively, compared to 72.9% and 5.1 with the current criteria).

Conclusion

There was a high frequency of skin disease among patients with juvenile DM who did not meet the PGA criterion for inactive disease but met the other 3 criteria. Incorporating PGA as an essential criterion for clinically inactive disease helps prevent the misclassification of patients with active skin disease.

Synovial Regulatory T Cells Occupy a Discrete TCR Niche in Human Arthritis and Require Local Signals To Stabilize FOXP3 Protein Expression

Although there is great interest in harnessing the immunosuppressive potential of FOXP3⁺ regulatory T cells (Tregs) for treating autoimmunity, a sizeable knowledge gap exists regarding Treg fate in human disease. In juvenile idiopathic arthritis (JIA) patients, we have previously reported that atypical CD25⁺FOXP3⁻ Treg-like cells uniquely populate the inflamed site. Intriguingly, their proportions relative to CD25⁺FOXP3⁺ Tregs associate with arthritis course, suggesting a role in disease. The ontogeny of these FOXP3⁻ Treg-like cells is, however, unknown. In this study, we interrogated clonal relationships between CD4⁺ T cell subsets in JIA, using high-throughput TCR repertoire analysis. We reveal that FOXP3⁺ Tregs possess highly exclusive TCRβ usage from conventional T cells, in blood, and also at the inflamed site, where they are clonally expanded. Intriguingly, the repertoires of FOXP3⁺ Tregs in synovial fluid are highly overlapping with CD25⁺FOXP3⁻ Treg-like cells, indicating fluctuations in FOXP3 expression in the inflamed joint. Furthermore, cultured synovial Tregs rapidly downregulated FOXP3 protein (but not mRNA), and this process was prevented by addition of synovial fluid from JIA patients, through an IL-6–independent mechanism. Our findings suggest that most Tregs arise from a separate lineage from conventional T cells, and that this repertoire divergence is largely maintained under chronic inflammatory conditions. We propose that subsequent Treg expansions at the inflamed site creates an environment that leads to competition for limited resources within the synovium, resulting in the destabilization of FOXP3 expression in some Tregs.

Methotrexate polyglutamates as a potential marker of adherence to long-term therapy in children with juvenile idiopathic arthritis and juvenile dermatomyositis: an observational, cross-sectional study

Introduction

Methotrexate (MTX) is a cornerstone of treatment in a wide variety of inflammatory conditions, including juvenile idiopathic arthritis (JIA) and juvenile dermatomyositis (JDM). However, owing to its narrow therapeutic index and the considerable interpatient variability in clinical response, monitoring of adherence to MTX is important. The present study demonstrates the feasibility of using methotrexate polyglutamates (MTXPGs) as a biomarker to measure adherence to MTX treatment in children with JIA and JDM.

Methods

Data were collected prospectively from a cohort of 48 children (median age 11.5 years) who received oral or subcutaneous (SC) MTX therapy for JIA or JDM. Dried blood spot samples were obtained from children by finger pick at the clinic or via self- or parent-led sampling at home, and they were analysed to determine the variability in MTXPG concentrations and assess adherence to MTX therapy.

Results

Wide fluctuations in MTXPG total concentrations (>2.0-fold variations) were found in 17 patients receiving stable weekly doses of MTX, which is indicative of nonadherence or partial adherence to MTX therapy. Age (P = 0.026) and route of administration (P = 0.005) were the most important predictors of nonadherence to MTX treatment. In addition, the study showed that MTX dose and route of administration were significantly associated with variations in the distribution of MTXPG subtypes. Higher doses and SC administration of MTX produced higher levels of total MTXPGs and selective accumulation of longer-chain MTXPGs (P < 0.001 and P < 0.0001, respectively).

Conclusions

Nonadherence to MTX therapy is a significant problem in children with JIA and JDM. The present study suggests that patients with inadequate adherence and/or intolerance to oral MTX may benefit from SC administration of the drug. The clinical utility of MTXPG levels to monitor and optimise adherence to MTX in children has been demonstrated.

Trial registration

ISRCTN Registry identifier: ISRCTN93945409. Registered 2 December 2011.

Genome-wide association study identifies HLA 8.1 ancestral haplotype alleles as major genetic risk factors for myositis phenotypes

Autoimmune muscle diseases (myositis) comprise a group of complex phenotypes influenced by genetic and environmental factors. To identify genetic risk factors in patients of European ancestry, we conducted a genome-wide association study (GWAS) of the major myositis phenotypes in a total of 1710 cases, which included 705 adult dermatomyositis, 473 juvenile dermatomyositis, 532 polymyositis and 202 adult dermatomyositis, juvenile dermatomyositis or polymyositis patients with anti-histidyl-tRNA synthetase (anti-Jo-1) autoantibodies, and compared them with 4724 controls. Single-nucleotide polymorphisms showing strong associations (P<5×10(-8)) in GWAS were identified in the major histocompatibility complex (MHC) region for all myositis phenotypes together, as well as for the four clinical and autoantibody phenotypes studied separately. Imputation and regression analyses found that alleles comprising the human leukocyte antigen (HLA) 8.1 ancestral haplotype (AH8.1) defined essentially all the genetic risk in the phenotypes studied. Although the HLA DRB1*03:01 allele showed slightly stronger associations with adult and juvenile dermatomyositis, and HLA B*08:01 with polymyositis and anti-Jo-1 autoantibody-positive myositis, multiple alleles of AH8.1 were required for the full risk effects. Our findings establish that alleles of the AH8.1 comprise the primary genetic risk factors associated with the major myositis phenotypes in geographically diverse Caucasian populations.

Dense genotyping of immune-related loci in idiopathic inflammatory myopathies confirms HLA alleles as the strongest genetic risk factor and suggests different genetic background for major clinical subgroups

OBJECTIVES

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases characterised by muscle weakness and extramuscular manifestations such as skin rashes and interstitial lung disease. We genotyped 2566 IIM cases of Caucasian descent using the Immunochip; a custom array covering 186 established autoimmune susceptibility loci. The cohort was predominantly comprised of patients with dermatomyositis (DM, n=879), juvenile DM (JDM, n=481), polymyositis (PM, n=931) and inclusion body myositis (n=252) collected from 14 countries through the Myositis Genetics Consortium.

RESULTS

The human leucocyte antigen (HLA) and PTPN22 regions reached genome-wide significance (p<5×10(-8)). Nine regions were associated at a significance level of p<2.25×10(-5), including UBE2L3, CD28 and TRAF6, with evidence of independent effects within STAT4. Analysis of clinical subgroups revealed distinct differences between PM, and DM and JDM. PTPN22 was associated at genome-wide significance with PM, but not DM and JDM, suggesting this effect is driven by PM. Additional suggestive associations including IL18R1 and RGS1 in PM and GSDMB in DM were identified. HLA imputation confirmed that alleles HLA-DRB1*03:01 and HLA-B*08:01 of the 8.1 ancestral haplotype (8.1AH) are most strongly associated with IIM, and provides evidence that amino acids within the HLA, such as HLA-DQB1 position 57 in DM, may explain part of the risk in this locus. Associations with alleles outside the 8.1AH reveal differences between PM, DM and JDM.

CONCLUSIONS

This work represents the largest IIM genetic study to date, reveals new insights into the genetic architecture of these rare diseases and suggests different predominating pathophysiology in different clinical subgroups.

Advances in the treatment of polyarticular juvenile idiopathic arthritis

PURPOSE OF REVIEW

To review recent advances in the management strategies of polyarticular course juvenile idiopathic arthritis (JIA) and identify unanswered questions and avenues for further research.

RECENT FINDINGS

There is evidence for an early, aggressive, treat-to-target approach for polyarticular JIA. Clinical disease activity criteria have been recently defined and validated, including criteria for inactive disease and the juvenile arthritis disease activity score (JADAS). There is a need for evidence-based, defined disease targets and biomarkers for prediction of response, including targets for remission induction, and guidelines on drug withdrawal. Recent treatment consensus plans and guidelines are discussed and compared, including the 2015 NHS England clinical policy statement, the 2014 Childhood Arthritis and Rheumatology Research Alliance (CARRA) treatment plans and the 2011 American College of Rheumatology (ACR) guidelines. Evidence for new agents such as tocilizumab, rituximab, golimumab, ustekinumab, certolizumab and tofacitinib is promising: the recent clinical trials are summarized here. Stratification of individual patient treatment remains a goal, and predictive biomarkers have been shown to predict success in the withdrawal of methotrexate therapy.

SUMMARY

There are promising advances in the treatment approaches, disease activity criteria, clinical guidelines, pharmaceutical choices and individually stratified therapy choices for polyarticular JIA.

MRP8/14 serum levels as a predictor of response to starting and stopping anti-TNF treatment in juvenile idiopathic arthritis

Introduction

Approximately 30 % of juvenile idiopathic arthritis (JIA) patients fail to respond to anti-TNF treatment. When clinical remission is induced, some patients relapse after treatment has been stopped. We tested the predictive value of MRP8/14 serum levels to identify responders to treatment and relapse after discontinuation of therapy.

Methods

Samples from 88 non-systemic JIA patients who started and 26 patients who discontinued TNF-blockers were analyzed. MRP8/14 serum levels were measured by in-house MRP8/14 ELISA and by Bühlmann Calprotectin ELISA at start of anti-TNF treatment, within 6 months after start and at discontinuation of etanercept in clinical remission. Patients were categorized into responders (ACRpedi ≥ 50 and/or inactive disease) and non-responders (ACRpedi < 50) within six months after start, response was evaluated by change in JADAS-10. Disease activity was assessed within six months after discontinuation.

Results

Baseline MRP8/14 levels were higher in responders (median MRP8/14 of 1466 ng/ml (IQR 1045–3170)) compared to non-responders (median MRP8/14 of 812 (IQR 570–1178), p < 0.001). Levels decreased after start of treatment only in responders (p < 0.001). Change in JADAS-10 was correlated with baseline MRP8/14 levels (Spearman’s rho 0.361, p = 0.001). Patients who flared within 6 months after treatment discontinuation had higher MRP8/14 levels (p = 0.031, median 1025 ng/ml (IQR 588–1288)) compared to patients with stable remission (505 ng/ml (IQR 346–778)). Results were confirmed by Bühlmann ELISA with high reproducibility but different overall levels.

Conclusion

High levels of baseline MRP8/14 are associated with good response to anti-TNF treatment, whereas elevated MRP8/14 levels at discontinuation of etanercept are associated with higher chance to flare.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0723-1) contains supplementary material, which is available to authorized users.

Development of an internationally agreed minimal dataset for juvenile dermatomyositis (JDM) for clinical and research use

BACKGROUND

Juvenile dermatomyositis (JDM) is a rare autoimmune inflammatory disorder associated with significant morbidity and mortality. International collaboration is necessary to better understand the pathogenesis of the disease, response to treatment and long-term outcome. To aid international collaboration, it is essential to have a core set of data that all researchers and clinicians collect in a standardised way for clinical purposes and for research. This should include demographic details, diagnostic data and measures of disease activity, investigations and treatment. Variables in existing clinical registries have been compared to produce a provisional data set for JDM. We now aim to develop this into a consensus-approved minimum core dataset, tested in a wider setting, with the objective of achieving international agreement.

METHODS/DESIGN

A two-stage bespoke Delphi-process will engage the opinion of a large number of key stakeholders through Email distribution via established international paediatric rheumatology and myositis organisations. This, together with a formalised patient/parent participation process will help inform a consensus meeting of international experts that will utilise a nominal group technique (NGT). The resulting proposed minimal dataset will be tested for feasibility within existing database infrastructures. The developed minimal dataset will be sent to all internationally representative collaborators for final comment. The participants of the expert consensus group will be asked to draw together these comments, ratify and 'sign off' the final minimal dataset.

DISCUSSION

An internationally agreed minimal dataset has the potential to significantly enhance collaboration, allow effective communication between groups, provide a minimal standard of care and enable analysis of the largest possible number of JDM patients to provide a greater understanding of this disease. The final approved minimum core dataset could be rapidly incorporated into national and international collaborative efforts, including existing prospective databases, and be available for use in randomised controlled trials and for treatment/protocol comparisons in cohort studies.

The association between low socioeconomic status with high physical limitations and low illness self-perception in patients with juvenile idiopathic arthritis: results from the Childhood Arthritis Prospective Study

Objective

To examine the association between socioeconomic status (SES) and delay to a pediatric rheumatology clinic, disease severity, and illness perception in patients with juvenile idiopathic arthritis in England.

Methods

Using the Index of Multiple Deprivation, 923 consecutive children from the Childhood Arthritis Prospective Study were assigned to SES groups: high‐SES (19.1%), middle‐SES (44.5%), or low‐SES (36.4%). At baseline, disease activity was assessed, and the Childhood Health Assessment Questionnaire (C‐HAQ), the Illness Perception Questionnaire, and the Child Health Questionnaire, version Parent Form 50, were completed. Linear median regression analyses or zero‐inflated negative binominal (ZINB) regression analyses were used.

Results

Delay to first pediatric rheumatology consultation was the same between the 3 SES groups. Although disease activity scores assessed by the pediatric rheumatologist did not differ between the 3 SES groups, persons in the low‐SES group recorded higher C‐HAQ scores compared to the high‐SES group (zero‐inflated part of ZINB odds ratio 0.28 [95% confidence interval (95% CI) 0.14, 0.55], count part of ZINB β 0.26 [95% CI 0.05, 0.48]). Parents with low SES also reported more often that their children's school work or activities with friends had been limited. Furthermore, the low‐SES group had a worse perception about the consequences of the disease and the effect of treatment than those in the high‐SES group.

Conclusion

Patients from a low‐SES background report more problems with daily activities and have a lower perception of the consequences of the disease than patients from a high‐SES background, warranting special attention from a multidisciplinary team.

Correlation of low CD73 expression on synovial lymphocytes with reduced adenosine generation and higher disease severity in juvenile idiopathic arthritis

Objective

To investigate the expression and adenosine‐generating activity of the ecto‐5′‐nucleotidase CD73 on synovial fluid mononuclear cells (SFMCs) and peripheral blood mononuclear cells (PBMCs) from children with juvenile idiopathic arthritis (JIA).

Methods

Given the role of CD73 protein in the production of antiinflammatory adenosine and its intersection with inflammatory biologic pathways, the expression of CD73 on SF and PB lymphocytes from patients with JIA and PB lymphocytes from healthy control subjects was determined by flow cytometry. The AMPase activity of CD73 on PBMCs and SFMCs was measured by high‐performance liquid chromatography. The effects of cell activation on CD73 expression were examined by in vitro culture of PBMCs.

Results

CD8+ and CD19+ SFMCs from patients with JIA expressed decreased levels of CD73 when compared to paired PBMCs from JIA patients and PBMCs from healthy controls. When the percentages of CD73+ synovial lymphocytes were compared between the 2 clinical forms of oligoarthritis, children with extended oligoarthritis showed lower CD73 expression compared to those with the milder form of the disease. CD8+ SFMCs had a lower ability to produce adenosine from etheno‐AMP compared to CD8+ PBMCs. T cell activation through the T cell receptor (TLR) of CD8+CD73+ cells and B cell activation through TLR‐9 resulted in reduced expression of CD73. This down‐regulation occurred on dividing cells.

Conclusion

These findings show that low CD73 expression on T and B cells in the inflamed site is related to cell proliferation and is correlated with the clinical severity of oligoarticular JIA. The decreased CD73 expression on SFMCs, in turn, results in reduced adenosine production, which leads to a decreased potential for antiinflammatory activity.

T cell expression of granulocyte-macrophage colony-stimulating factor in juvenile arthritis is contingent upon Th17 plasticity

OBJECTIVE

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a potent inflammatory mediator that is responsible for recruitment and activation of innate immune cells. Recent data from murine studies have identified Th17 cells as a key source of GM-CSF and suggest that T cell-derived GM-CSF is instrumental in the induction of autoimmune disease. The present study was undertaken to analyze the expression of T cell-derived GM-CSF in the joints of patients with juvenile idiopathic arthritis (JIA) and to investigate the differentiation of Th17 cells and how this relates to GM-CSF+ T helper cells.

METHODS

Synovial fluid (SF) and peripheral blood (PB) samples from 24 patients with JIA were analyzed, by flow cytometry and reverse transcription-polymerase chain reaction, for expression of GM-CSF and the Th17 marker CD161. A cytokine capture assay was used to purify Th17 cells and test the plasticity of cytokine production in response to interleukin-12 (IL-12) and IL-23.

RESULTS

The frequency of GM-CSF-producing T helper cells was significantly enriched in SF mononuclear cells compared to PB mononuclear cells from the patients with JIA (24.1% of CD4+ T cells versus 2.9%) and closely correlated with the erythrocyte sedimentation rate (r(2) = 0.91, P < 0.001). Synovial GM-CSF+ T cells were predominantly CD161+ and coexpressed interferon-γ (IFNγ), but not IL-17. Culture of Th17 cells in the presence of IL-12 led to rapid up-regulation of GM-CSF and IFNγ, recapitulating the phenotype of GM-CSF-expressing cells within the joint.

CONCLUSION

Our results identify a novel outcome of Th17 plasticity in humans that may account for the enrichment of GM-CSF-expressing T cells in the joints of patients with JIA. The association of GM-CSF expression with systemic inflammation highlights the potential role of Th17-related cytokines in the pathology of JIA.

Hypomethylation at the regulatory T cell-specific demethylated region in CD25hi T cells is decoupled from FOXP3 expression at the inflamed site in childhood arthritis

The maintenance of FOXP3 expression in CD25^hi regulatory T cells (Tregs) is crucial to the control of inflammation and essential for successful Treg transfer therapies. Coexpression of CD25 and FOXP3 in combination with a hypomethylated region within the FOXP3 gene, called the Treg-specific demethylated region (TSDR), is considered the hallmark of stable Tregs. The TSDR is an epigenetic motif that is important for stable FOXP3 expression and is used as a biomarker to measure Treg lineage commitment. In this study, we report that, unlike in peripheral blood, CD4⁺ T cell expression of CD25 and FOXP3 is frequently dissociated at the inflamed site in patients with juvenile idiopathic arthritis, which led us to question the stability of human Tregs in chronic inflammatory environments. We describe a novel CD4⁺CD127^loCD25^hi human T cell population that exhibits extensive TSDR and promoter demethylation in the absence of stable FOXP3 expression. This population expresses high levels of CTLA-4 and can suppress T conventional cell proliferation in vitro. These data collectively suggest that this population may represent a chronically activated FOXP3^lo Treg population. We show that these cells have defects in IL-2 signaling and reduced expression of a deubiquitinase important for FOXP3 stability. Clinically, the proportions of these cells within the CD25^hi T cell subset are increased in patients with the more severe courses of disease. Our study demonstrates, therefore, that hypomethylation at the TSDR can be decoupled from FOXP3 expression in human T cells and that environment-specific breakdown in FOXP3 stability may compromise the resolution of inflammation in juvenile idiopathic arthritis.

Developing a provisional, international minimal dataset for Juvenile Dermatomyositis: for use in clinical practice to inform research

BACKGROUND

Juvenile dermatomyositis (JDM) is a rare but severe autoimmune inflammatory myositis of childhood. International collaboration is essential in order to undertake clinical trials, understand the disease and improve long-term outcome. The aim of this study was to propose from existing collaborative initiatives a preliminary minimal dataset for JDM. This will form the basis of the future development of an international consensus-approved minimum core dataset to be used both in clinical care and inform research, allowing integration of data between centres.

METHODS

A working group of internationally-representative JDM experts was formed to develop a provisional minimal dataset. Clinical and laboratory variables contained within current national and international collaborative databases of patients with idiopathic inflammatory myopathies were scrutinised. Judgements were informed by published literature and a more detailed analysis of the Juvenile Dermatomyositis Cohort Biomarker Study and Repository, UK and Ireland.

RESULTS

A provisional minimal JDM dataset has been produced, with an associated glossary of definitions. The provisional minimal dataset will request information at time of patient diagnosis and during on-going prospective follow up. At time of patient diagnosis, information will be requested on patient demographics, diagnostic criteria and treatments given prior to diagnosis. During on-going prospective follow-up, variables will include the presence of active muscle or skin disease, major organ involvement or constitutional symptoms, investigations, treatment, physician global assessments and patient reported outcome measures.

CONCLUSIONS

An internationally agreed minimal dataset has the potential to significantly enhance collaboration, allow effective communication between groups, provide a minimal standard of care and enable analysis of the largest possible number of JDM patients to provide a greater understanding of this disease. This preliminary dataset can now be developed into a consensus-approved minimum core dataset and tested in a wider setting with the aim of achieving international agreement.

Immunological characteristics and T-cell receptor clonal diversity in children with systemic juvenile idiopathic arthritis undergoing T-cell-depleted autologous stem cell transplantation

Children with systemic Juvenile Idiopathic Arthritis (sJIA), the most severe subtype of JIA, are at risk from destructive polyarthritis and growth failure, and corticosteroids as part of conventional treatment can result in osteoporosis and growth delay. In children where there is failure or toxicity from drug therapies, disease has been successfully controlled by T-cell-depleted autologous stem cell transplantation (ASCT). At present, the immunological basis underlying remission after ASCT is unknown. Immune reconstitution of T cells, B cells, natural killer cells, natural killer T cells and monocytes, in parallel with T-cell receptor (TCR) diversity by analysis of the β variable region (TCRVb) complementarity determining region-3 (CDR3) using spectratyping and sequencing, were studied in five children with sJIA before and after ASCT. At time of follow up (mean 11·5 years), four patients remain in complete remission, while one child relapsed within 1 month of transplant. The CD8⁺ TCRVb repertoire was highly oligoclonal early in immune reconstitution and re-emergence of pre-transplant TCRVb CDR3 dominant peaks was observed after transplant in certain TCRVb families. Further, re-emergence of pre-ASCT clonal sequences in addition to new sequences was identified after transplant. These results suggest that a chimeric TCR repertoire, comprising T-cell clones developed before and after transplant, can be associated with clinical remission from severe arthritis.

Anti-MDA5 autoantibodies in juvenile dermatomyositis identify a distinct clinical phenotype: a prospective cohort study

INTRODUCTION

The aim of this study was to define the frequency and associated clinical phenotype of anti-MDA5 autoantibodies in a large UK based, predominantly Caucasian, cohort of patients with juvenile dermatomyositis (JDM).

METHODS

Serum samples and clinical data were obtained from 285 patients with JDM recruited to the UK Juvenile Dermatomyositis Cohort and Biomarker Study. The presence of anti-MDA5 antibodies was determined by immunoprecipitation and confirmed by ELISA using recombinant MDA5 protein. Results were compared with matched clinical data, muscle biopsies (scored by an experienced paediatric neuropathologist) and chest imaging (reviewed by an experienced paediatric radiologist).

RESULTS

Anti-MDA5 antibodies were identified in 7.4% of JDM patients and were associated with a distinct clinical phenotype including skin ulceration (P = 0.03) oral ulceration (P = 0.01), arthritis (P <0.01) and milder muscle disease both clinically (as determined by Childhood Myositis Assessment Score (P = 0.03)) and histologically (as determined by a lower JDM muscle biopsy score (P <0.01)) than patients who did not have anti-MDA5 antibodies. A greater proportion of children with anti-MDA5 autoantibodies achieved disease inactivity at two years post-diagnosis according to PRINTO criteria (P = 0.02). A total of 4 out of 21 children with anti-MDA5 had interstitial lung disease; none had rapidly progressive interstitial lung disease.

CONCLUSIONS

Anti-MDA5 antibodies can be identified in a small but significant proportion of patients with JDM and identify a distinctive clinical sub-group. Screening for anti-MDA5 autoantibodies at diagnosis would be useful to guide further investigation for lung disease, inform on prognosis and potentially confirm the diagnosis, as subtle biopsy changes could otherwise be missed.

Calcinosis in juvenile dermatomyositis is influenced by both anti-NXP2 autoantibody status and age at disease onset

OBJECTIVE

Calcinosis is a major cause of morbidity in JDM and has previously been linked to anti-NXP2 autoantibodies, younger age at disease onset and more persistent disease activity. This study aimed to investigate the clinical associations of anti-NXP2 autoantibodies in patients with JDM stratified by age at disease onset.

METHODS

A total of 285 patients with samples and clinical data were recruited via the UK Juvenile Dermatomyositis Cohort and Biomarker Study. The presence of anti-NXP2 was determined by both immunoprecipitation and ELISA. Logistic regression analysis was performed to assess the age-dependent relationship between anti-NXP2 and the development of calcinosis and disease activity measures.

RESULTS

We identified anti-NXP2 autoantibodies in 56 patients (20%). While in all patients younger age at disease onset was associated with an increased risk of calcinosis and this relationship was nearly linear, anti-NXP2 autoantibodies substantially increased the risk of calcinosis across all ages (P = 0.025) and were detectable prior to calcinosis development. Children with anti-NXP2 autoantibodies had a greater degree of weakness (median lowest ever Childhood Myositis Assessment Score 29.6 vs 42) and were less likely to be in remission at 2 years post-diagnosis. No difference in disease activity was seen 4 years post-diagnosis.

CONCLUSION

Children diagnosed at a young age have a high risk of calcinosis regardless of autoantibody status. However, the presence of anti-NXP2 autoantibodies substantially increases the risk of calcinosis across all ages and is associated with disease severity.

A novel dried blood spot-LCMS method for the quantification of methotrexate polyglutamates as a potential marker for methotrexate use in children

Objective

Development and validation of a selective and sensitive LCMS method for the determination of methotrexate polyglutamates in dried blood spots (DBS).

Methods

DBS samples [spiked or patient samples] were prepared by applying blood to Guthrie cards which was then dried at room temperature. The method utilised 6-mm disks punched from the DBS samples (equivalent to approximately 12 µl of whole blood). The simple treatment procedure was based on protein precipitation using perchloric acid followed by solid phase extraction using MAX cartridges. The extracted sample was chromatographed using a reversed phase system involving an Atlantis T3-C18 column (3 µm, 2.1×150 mm) preceded by Atlantis guard column of matching chemistry. Analytes were subjected to LCMS analysis using positive electrospray ionization.

Key Results

The method was linear over the range 5–400 nmol/L. The limits of detection and quantification were 1.6 and 5 nmol/L for individual polyglutamates and 1.5 and 4.5 nmol/L for total polyglutamates, respectively. The method has been applied successfully to the determination of DBS finger-prick samples from 47 paediatric patients and results confirmed with concentrations measured in matched RBC samples using conventional HPLC-UV technique.

Conclusions and Clinical Relevance

The methodology has a potential for application in a range of clinical studies (e.g. pharmacokinetic evaluations or medication adherence assessment) since it is minimally invasive and easy to perform, potentially allowing parents to take blood samples at home. The feasibility of using DBS sampling can be of major value for future clinical trials or clinical care in paediatric rheumatology.

Genome-wide association study of dermatomyositis reveals genetic overlap with other autoimmune disorders

OBJECTIVE

To identify new genetic associations with juvenile and adult dermatomyositis (DM).

METHODS

We performed a genome-wide association study (GWAS) of adult and juvenile DM patients of European ancestry (n = 1,178) and controls (n = 4,724). To assess genetic overlap with other autoimmune disorders, we examined whether 141 single-nucleotide polymorphisms (SNPs) outside the major histocompatibility complex (MHC) locus, and previously associated with autoimmune diseases, predispose to DM.

RESULTS

Compared to controls, patients with DM had a strong signal in the MHC region consisting of GWAS-level significance (P < 5 × 10(-8)) at 80 genotyped SNPs. An analysis of 141 non-MHC SNPs previously associated with autoimmune diseases showed that 3 SNPs linked with 3 genes were associated with DM, with a false discovery rate (FDR) of <0.05. These genes were phospholipase C-like 1 (PLCL1; rs6738825, FDR = 0.00089), B lymphoid tyrosine kinase (BLK; rs2736340, FDR = 0.0031), and chemokine (C-C motif) ligand 21 (CCL21; rs951005, FDR = 0.0076). None of these genes was previously reported to be associated with DM.

CONCLUSION

Our findings confirm the MHC as the major genetic region associated with DM and indicate that DM shares non-MHC genetic features with other autoimmune diseases, suggesting the presence of additional novel risk loci. This first identification of autoimmune disease genetic predispositions shared with DM may lead to enhanced understanding of pathogenesis and novel diagnostic and therapeutic approaches.

Validity of a three-variable Juvenile Arthritis Disease Activity Score in children with new-onset juvenile idiopathic arthritis

OBJECTIVES

To investigate the validity and feasibility of the Juvenile Arthritis Disease Activity Score (JADAS) in the routine clinical setting for all juvenile idiopathic arthritis (JIA) disease categories and explore whether exclusion of the erythrocyte sedimentation rate (ESR) from JADAS (the 'JADAS3') influences correlation with single markers of disease activity.

METHODS

JADAS-71, JADAS-27 and JADAS-10 were determined at baseline for an inception cohort of children with JIA in the Childhood Arthritis Prospective Study. JADAS3-71, JADAS3-27 and JADAS3-10 were determined using an identical formula but with exclusion of ESR. Correlation of JADAS with JADAS3 and single measures of disease activity/severity were determined by category.

RESULTS

Of 956 eligible children, sufficient data were available to calculate JADAS-71, JADAS-27 and JADAS-10 at baseline in 352 (37%) and JADAS3 in 551 (58%). The median (IQR) JADAS-71, JADAS-27 and JADAS-10 for all 352 children was 11 (5.9-18), 10.4 (5.7-17) and 11 (5.9-17.3), respectively. Median JADAS and JADAS3 varied significantly with the category (Kruskal-Wallis p=0.0001), with the highest values in children with polyarticular disease patterns. Correlation of JADAS and JADAS3 across all categories was excellent. Correlation of JADAS71 with single markers of disease activity/severity was good to moderate, with some variation across the categories. With the exception of ESR, correlation of JADAS3-71 was similar to correlation of JADAS-71 with the same indices.

CONCLUSIONS

This study is the first to apply JADAS to all categories of JIA in a routine clinical setting in the UK, adding further information about the feasibility and construct validity of JADAS. For the majority of categories, clinical applicability would be improved by exclusion of the ESR.

Update in juvenile myositis

PURPOSE OF REVIEW

This update on childhood idiopathic inflammatory myopathies (IIMs) reviews recent progress in the field of translational science and clinical research over the past 12-18 months.

RECENT FINDINGS

Several new studies, including results from the international genome-wide association study, point to abnormalities of the adaptive immune system in childhood IIMs. Circulating T-follicular helper cells promote plasma cell differentiation and have been found in high levels in juvenile dermatomyositis (JDM), which may account the frequency of autoantibodies seen in this disease. One of the latest to be identified in JDM targets the protein NXP-2 and is associated with an increased risk of calcinosis in young patients. The first randomized controlled clinical trial in refractory adult and childhood IIMs was reported this year. B-cell depletion with the anti-CD20 antibody, rituximab, failed to achieve its primary end point, but patients with JDM did show good improvement in disease activity. A new international definition of disease remission in JDM has been agreed, which will aid disease assessment in future therapeutic trials.

SUMMARY

The challenges of studying a rare disease such as JDM have been overcome by several collaborative studies and have led to significant progress in understanding the cause, treatment and prognosis of childhood IIMs.

Validation of a score tool for measurement of histological severity in juvenile dermatomyositis and association with clinical severity of disease

Objectives

To study muscle biopsy tissue from patients with juvenile dermatomyositis (JDM) in order to test the reliability of a score tool designed to quantify the severity of histological abnormalities when applied to biceps humeri in addition to quadriceps femoris. Additionally, to evaluate whether elements of the tool correlate with clinical measures of disease severity.

Methods

55 patients with JDM with muscle biopsy tissue and clinical data available were included. Biopsy samples (33 quadriceps, 22 biceps) were prepared and stained using standardised protocols. A Latin square design was used by the International Juvenile Dermatomyositis Biopsy Consensus Group to score cases using our previously published score tool. Reliability was assessed by intraclass correlation coefficient (ICC) and scorer agreement (α) by assessing variation in scorers’ ratings. Scores from the most reliable tool items correlated with clinical measures of disease activity at the time of biopsy.

Results

Inter- and intraobserver agreement was good or high for many tool items, including overall assessment of severity using a Visual Analogue Scale. The tool functioned equally well on biceps and quadriceps samples. A modified tool using the most reliable score items showed good correlation with measures of disease activity.

Conclusions

The JDM biopsy score tool has high inter- and intraobserver agreement and can be used on both biceps and quadriceps muscle tissue. Importantly, the modified tool correlates well with clinical measures of disease activity. We propose that standardised assessment of muscle biopsy tissue should be considered in diagnostic investigation and clinical trials in JDM.

Myeloid related protein induces muscle derived inflammatory mediators in juvenile dermatomyositis

Introduction

The aetiopathogenesis of juvenile dermatomyositis (JDM) remains poorly understood. In particular the contribution of monocytes or macrophages, which are frequently observed to be an infiltrate within muscle tissue very early in the disease process, is unknown. We hypothesised that these cells secrete the pro-inflammatory myeloid related protein (MRP) 8/14 which may then contribute to muscle pathology in JDM.

Methods

In this study of 56 JDM patients, serum MRP8/14 levels were compared with clinical measures of disease activity. Muscle biopsies taken early in disease were assessed by immunohistochemistry to determine the frequency and identity of MRP-expressing cells. The effects of MRP stimulation and endoplasmic reticulum (ER) stress on muscle were tested in vitro. Serum or supernatant levels of cytokines were analyzed by multiplex immunoassay.

Results

Serum MRP8/14 correlated with physician’s global assessment of disease activity in JDM (R = 0.65, p = 0.0003) and muscle strength/endurance, childhood myositis assessment score (CMAS, R = −0.55, p = 0.004). MRP8/14 was widely expressed by CD68+ macrophages in JDM muscle tissue. When cultured with human myoblasts, MRP8 led to the secretion of MCP-1 and IL-6, which was enhanced by ER stress. Both inflammatory mediators were detected in significantly higher levels in the serum of JDM patients compared to healthy controls.

Conclusions

This study is the first to identify serum MRP8/14 as a potential biomarker for disease activity in JDM. We propose that tissue infiltrating macrophages secreting MRP8/14 may contribute to myositis, by driving the local production of cytokines directly from muscle.

Adaptation of the methotrexate in rheumatoid arthritis knowledge questionnaire (MiRAK) for use with parents of children with juvenile idiopathic arthritis: a qualitative study

BACKGROUND

Although Methotrexate (MTX) is one of the most commonly prescribed disease-modifying drugs in JIA no questionnaire exists that assesses the knowledge of parents about this drug. A 60-item questionnaire was recently developed to measure rheumatoid arthritis (RA) patients' knowledge about MTX; the Methotrexate in Rheumatoid Arthritis Knowledge Test (MiRAK; Ciciriello et al. (Arthritis Rheum 62:10-1009, 2010)). This study aimed to adapt the MiRAK for parents of children with JIA.

METHODS

Adaption of the MiRAK involved: 1) email consultations with clinicians working in the field of paediatric rheumatology (Panel 1) to ascertain the potential adaptations of the MiRAK from a clinical perspective, 2) synthesis of clinicians' suggestions by a panel of experts, researchers and MiRAK developers (Panel 2) to reach consensus on which items needed to be modified and create a draft Methotrexate in Juvenile Idiopathic Arthritis Knowledge Test (MiJIAK), 3) a review of the draft by 5 parents of children with JIA (Panel 3) using the cognitive 'think-aloud' method, 4) a second consultation with Panel 2 to review parents' suggestions and determine the final items.

RESULTS

A total of 9 items remained unchanged, e.g. "Methotrexate is effective at relieving joint stiffness", 19 were deemed inappropriate in the paediatric setting and deleted, e.g. "It is safe to become pregnant 3 weeks after methotrexate has been stopped", 32 underwent editorial changes largely to indicate that the questionnaire was about the children with JIA, e.g. "If you forget to give a dose of Methotrexate, you can still take it the next day" became "If your child misses a dose of Methotrexate, they can still take it the next day", and 1 new item was added. A new 42-item questionnaire was produced and was found to be well understood by parents of children with JIA.

CONCLUSIONS

The systematic modification of the MiRAK, a patient-centred MTX knowledge questionnaire, has generated a comprehensive new questionnaire for use in the JIA setting. The wide consultation process, including cognitive testing, has ensured the tool is both relevant and acceptable to clinicians and will therefore be a valuable addition in understanding the parents' perspective of this treatment in JIA.

Mothers' reports of the difficulties that their children experience in taking methotrexate for Juvenile Idiopathic Arthritis and how these impact on quality of life

BACKGROUND

Children who take methotrexate for juvenile idiopathic arthritis may experience side effects, including nausea and vomiting, leading to anticipatory nausea in some children, and fear of injections or blood tests. The aim of this study was to examine the prevalence and extent of these difficulties and their impact on quality of life.

METHODS

Participants were mothers of children with JIA who were currently taking methotrexate (MTX). Mothers completed a questionnaire about MTX that was developed for the study, two questions from the treatment subscale of the Pediatric Quality of Life Inventory (PedsQL) Rheumatology scale to assess needle-related problems and the Child Health Questionnaire 50-item parent version (CHQ-PF50) to assess health-related quality of life (HRQoL).

RESULTS

171 mothers participated in the study. More than half of children were reported to have experienced one or more of: nausea or vomiting after taking MTX, anticipatory nausea, fear of blood tests or fear of injections. There was no significant difference in reported rates of sickness or needle-related problems between MTX responders (ACR70 or above), partial responders (ACR30 or ACR50) and non-responders. In multivariate analyses, variables that were significant independent predictors of one or more MTX-related difficulties included younger age, taking MTX subcutaneously and having a larger number of currently active joints. Feeling sick after taking MTX was a significant independent predictor of poorer scores on the physical summary scale of the CHQ-PF50. Anxiety about injections and feeling sick after taking MTX were significant independent predictors of poorer scores on the psychosocial summary scale.

CONCLUSIONS

Difficulties in taking MTX are experienced by a significant proportion of children with JIA and these may have an adverse impact on HRQoL. Approaches to help minimize these difficulties are required.

Limb girdle muscular dystrophy type 2B masquerading as inflammatory myopathy: case report

Limb girdle muscular dystrophy type 2B is a rare subtype of muscular dystrophy, the predominant feature of which is muscle weakness. The disease is caused by an autosomal recessively inherited reduction/absence of muscle dysferlin due to a mutation in dysferlin gene at 2p12-14. We report a 10 year old boy who presented with severe non-transient right knee pain and swelling, which later became bilateral. His pain was worst in the morning and during rest. Blood tests revealed markedly raised creatine kinase values (highest 22, 297 U/l), raising the possibility of an inflammatory myositis. MRI showed bilateral asymmetrical muscle involvement of thighs and calves with oedematous changes mimicking the imaging appearances of inflammatory myositis. CRP and ESR levels were consistently within normal limits. Over several months his knee pain worsened and limited walking. Muscle biopsy revealed a severe reduction of dysferlin immunostaining, indicating the diagnosis, which was confirmed by 2 compound heterozygous pathogenic mutations in the dysferlin gene. It is not unusual for this subtype of the disease to mimic myositis: however, significant pain is a rare presenting symptom. Given the significant overlap between this form of muscular dystrophy and inflammatory myopathies, a high index of suspicion is needed to ensure an accurate and timely diagnosis. Furthermore, characteristic inflammatory-related morning pain should not rule out consideration of non-inflammatory causes.

Adult and juvenile dermatomyositis: are the distinct clinical features explained by our current understanding of serological subgroups and pathogenic mechanisms?

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

Morphometric analyses of normal pediatric brachial biceps and quadriceps muscle tissue

Pediatric normal brachial biceps (14 specimens) and quadriceps muscles (14 specimens) were studied by immunohistochemistry to quantify fiber-type, diameter and distribution, capillary density, presence of inflammatory cells (CD3, CD20, CD68) and expression of neonatal myosin and MHC class 1 proteins. Brachial biceps showed more fast-twitch fibers and lower capillary/fiber ratio than quadriceps. The mean diameter of both fiber types was smaller in biceps than quadriceps. Fast-fibers were smaller than slow-fibers, and capillary/fiber ratio was < 1.0 in both muscles. Fiber size and capillary / fiber ratio increased with age. Normal limits for infiltrating haematopoietic cells were <4 T lymphocytes, or CD68+ cells, very few B cells, < 6 neonatal myosin positive fibers, and no fibers MHC class 1 positive in one x20 field, for both muscles. The present comparison of quantitative findings between brachial biceps and quadriceps may allow standardization of the assessment of pathological changes in both pediatric muscles.

Comparison of children with onset of juvenile dermatomyositis symptoms before or after their fifth birthday in a UK and Ireland juvenile dermatomyositis cohort study

Objective

To compare 2 groups of children with juvenile dermatomyositis (DM), those with onset of symptoms before their fifth birthday versus those whose disease begins either on or after their fifth birthday, and to assess whether age at onset is associated with differences in disease presentation, treatments received, or outcomes 2 years after diagnosis.

Methods

Data were analyzed on children recruited to a UK juvenile DM cohort study with a diagnosis of probable or definite juvenile DM and less than 12 months between diagnosis and recruitment.

Results

Fifty-five (35%) of 157 children had onset of symptoms before their fifth birthday. At diagnosis, cutaneous ulceration was found in 32.7% of the younger group versus 11.8% of the older group (P = 0.003). Facial or body swelling was reported more often in the younger group, whereas headaches, alopecia, and Raynaud's phenomenon were all more frequently reported in the older group. At followup 2 years later, there were no important differences in outcomes between the groups. More than 90% of patients in both groups received both methotrexate and steroids. Twenty-three percent of both groups remained on steroids 2 years after diagnosis.

Conclusion

Our study showed that children with juvenile DM with disease onset at age <5 years are more likely to present with ulcerative skin disease and edema. There were no clinically significant differences in outcomes between the 2 groups.

Association of the IL-10 gene family locus on chromosome 1 with juvenile idiopathic arthritis (JIA)

Background

The cytokine IL-10 and its family members have been implicated in autoimmune diseases and we have previously reported that genetic variants in IL-10 were associated with a rare group of diseases called juvenile idiopathic arthritis (JIA). The aim of this study was to fine map genetic variants within the IL-10 cytokine family cluster on chromosome 1 using linkage disequilibrium (LD)-tagging single nucleotide polymorphisms (tSNPs) approach with imputation and conditional analysis to test for disease associations.

Methodology/Principal Findings

Fifty-three tSNPs were tested for association between Caucasian paediatric cohorts [219 systemic JIA (sJIA), 187 persistent oligoarticular JIA (pOJIA), and 139 extended OJIA (eOJIA) patients], and controls (Wellcome Trust control cohort, WTCCC2). Significant association with sJIA was detected at rs1400986 in the promoter of IL-20 (odds ratio 1.53; 95% CI 1.21–1.93; p = 0.0004), but in no other subtypes. Imputation analysis identified additional associated SNPs for pOJIA at IL-20 and IL-24, including a rare, functional, missense variant at IL-24 with a p = 0.0002. Penalised logistic regression analysis with HyperLasso and conditional analysis identified several further associations with JIA subtypes. In particular, haplotype analysis refined the sJIA association, with a joint effect at rs1400986 and rs4129024 in intron 1 of MAPKAPK2 (p = 3.2E−5). For pOJIA, a 3-SNP haplotype including rs1878672 in intron 3 of IL-10 showed evidence for association (p = 0.0018). In eOJIA, rs10863962 (3′UTR of FCAMR) and rs12409577 (intron of IL-19) haplotype showed some evidence of association (p = 0.0003).

Conclusions

This study supports previous association of IL-20 with sJIA. Haplotype analyses provided stronger association signals than single point analyses, while a penalised logistic regression approach also suggested multiple independent association signals. Replication studies are required to confirm or refute these findings. The results indicate that combined effects with unknown/rare variants remain to be characterised in JIA, and represent a possible example of synthetic association in this region.

Juvenile-onset inflammatory arthritis: a study of adolescents' beliefs about underlying cause

OBJECTIVE

Patients' beliefs regarding the cause of illness may influence treatment adherence and long-term outcome. Little is known of adolescents' beliefs regarding the cause of JIA. This study aims to identify adolescents' beliefs about the underlying cause of their arthritis at first presentation to the paediatric rheumatology department.

METHODS

One hundred and twenty-two adolescents aged ≥11 years participating in the larger prospective Childhood Arthritis Prospective Study, an inception cohort of childhood-onset inflammatory arthritis, were asked to complete a questionnaire regarding underlying beliefs about their arthritis. The top-listed causes were identified, and associations between beliefs and characteristics of the adolescents and their arthritis were compared across the different causal beliefs.

RESULTS

The most common causal beliefs were genetics (27.1%), the immune system (21.3%), accident or injury (15.6%) and infection (13.1%). Association between causal beliefs and gender, disease duration, International League Against Rheumatism subtype and source of referral was observed, although small numbers prevented robust statistical comparisons.

CONCLUSION

This first report on adolescents' beliefs about the cause of their juvenile arthritis found the most common causal beliefs to be related to genes or the immune system. Brief assessments of adolescents' beliefs at presentation will enable providers to modify or adapt potentially unhelpful beliefs and provide age-appropriate information regarding arthritis.