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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Identification and prediction of novel classes of long-term disease trajectories for patients with juvenile dermatomyositis using growth mixture models

Objectives

Uncertainty around clinical heterogeneity and outcomes for patients with JDM represents a major burden of disease and a challenge for clinical management. We sought to identify novel classes of patients having similar temporal patterns in disease activity and relate them to baseline clinical features.

Methods

Data were obtained for n = 519 patients, including baseline demographic and clinical features, baseline and follow-up records of physician’s global assessment of disease (PGA), and skin disease activity (modified DAS). Growth mixture models (GMMs) were fitted to identify classes of patients with similar trajectories of these variables. Baseline predictors of class membership were identified using Lasso regression.

Results

GMM analysis of PGA identified two classes of patients. Patients in class 1 (89%) tended to improve, while patients in class 2 (11%) had more persistent disease. Lasso regression identified abnormal respiration, lipodystrophy and time since diagnosis as baseline predictors of class 2 membership, with estimated odds ratios, controlling for the other two variables, of 1.91 for presence of abnormal respiration, 1.92 for lipodystrophy and 1.32 for time since diagnosis. GMM analysis of modified DAS identified three classes of patients. Patients in classes 1 (16%) and 2 (12%) had higher levels of modified DAS at diagnosis that improved or remained high, respectively. Patients in class 3 (72%) began with lower DAS levels that improved more quickly. Higher proportions of patients in PGA class 2 were in DAS class 2 (19%, compared with 16 and 10%).

Conclusion

GMM analysis identified novel JDM phenotypes based on longitudinal PGA and modified DAS.

Similarities and Differences Between Juvenile and Adult Spondyloarthropathies

Spondyloarthritis (SpA) encompasses a broad spectrum of conditions occurring from childhood to middle age. Key features of SpA include axial and peripheral arthritis, enthesitis, extra-articular manifestations, and a strong association with HLA-B27. These features are common across the ages but there are important differences between juvenile and adult onset disease. Juvenile SpA predominantly affects the peripheral joints and the incidence of axial arthritis increases with age. Enthesitis is important in early disease. This review article highlights the similarities and differences between juvenile and adult SpA including classification, pathogenesis, clinical features, imaging, therapeutic strategies, and disease outcomes. In addition, the impact of the biological transition from childhood to adulthood is explored including the importance of musculoskeletal and immunological maturation. We discuss how the changes associated with adolescence may be important in explaining age-related differences in the clinical phenotype between juvenile and adult SpA and their implications for the treatment of juvenile SpA.

Biomarkers of Response to Biologic Therapy in Juvenile Idiopathic Arthritis

Background: Juvenile idiopathic arthritis (JIA) is the most common chronic inflammatory arthritis of childhood, characterized by various clinical phenotypes associated with variable prognosis. Significant progress has been achieved with the use of biologic treatments, which specifically block pro-inflammatory molecules involved in the disease pathogenesis. The most commonly used biologics in JIA are monoclonal antibodies and recombinant proteins targeting interleukins 1 (IL-1) and 6 (IL-6), and tumor necrosis factor α (TNF-α). Several biomarkers have been investigated in JIA. Aims: To assess the level of evidence available regarding the role of biomarkers in JIA related to guiding clinical and therapeutic decisions, providing disease prognostic information, facilitating disease activity monitoring and assessing biologic treatment response in JIA, as well as propose new strategies for biologic therapy-related biomarker use in JIA. Methods: We searched PubMed for relevant literature using predefined key words corresponding to several categories of biomarkers to assess their role in predicting and assessing biologic treatment response and clinical remission in JIA. Results: We reviewed serological, cellular, genetic, transcriptomic and imaging biomarkers, to identify candidates that are both well-established and widely used, as well as newly investigated in JIA on biologic therapy. We evaluated their role in management of JIA as well as identified the unmet needs for new biomarker discovery and better clinical applications. Conclusion: Although there are no ideal biomarkers in JIA, we identified serological biomarkers with potential clinical utility. We propose strategies of combining biomarkers of response to biologics in JIA, as well as routine implementation of clinically acceptable imaging biomarkers for improved disease assessment performance.

Patient-reported wellbeing and clinical disease measures over time captured by multivariate trajectories of disease activity in individuals with juvenile idiopathic arthritis in the UK: a multicentre prospective longitudinal study

BACKGROUND

Juvenile idiopathic arthritis (JIA) is a heterogeneous disease, the signs and symptoms of which can be summarised with use of composite disease activity measures, including the clinical Juvenile Arthritis Disease Activity Score (cJADAS). However, clusters of children and young people might experience different global patterns in their signs and symptoms of disease, which might run in parallel or diverge over time. We aimed to identify such clusters in the 3 years after a diagnosis of JIA. The identification of these clusters would allow for a greater understanding of disease progression in JIA, including how physician-reported and patient-reported outcomes relate to each other over the JIA disease course.

METHODS

In this multicentre prospective longitudinal study, we included children and young people recruited before Jan 1, 2015, to the Childhood Arthritis Prospective Study (CAPS), a UK multicentre inception cohort. Participants without a cJADAS score were excluded. To assess groups of children and young people with similar disease patterns in active joint count, physician's global assessment, and patient or parental global evaluation, we used latent profile analysis at initial presentation to paediatric rheumatology and multivariate group-based trajectory models for the following 3 years. Optimal models were selected on the basis of a combination of model fit, clinical plausibility, and model parsimony.

FINDING

Between Jan 1, 2001, and Dec 31, 2014, 1423 children and young people with JIA were recruited to CAPS, 239 of whom were excluded, resulting in a final study population of 1184 children and young people. We identified five clusters at baseline and six trajectory groups using longitudinal follow-up data. Disease course was not well predicted from clusters at baseline; however, in both cross-sectional and longitudinal analyses, substantial proportions of children and young people had high patient or parent global scores despite low or improving joint counts and physician global scores. Participants in these groups were older, and a higher proportion of them had enthesitis-related JIA and lower socioeconomic status, compared with those in other groups.

INTERPRETATION

Almost one in four children and young people with JIA in our study reported persistent, high patient or parent global scores despite having low or improving active joint counts and physician's global scores. Distinct patient subgroups defined by disease manifestation or trajectories of progression could help to better personalise health-care services and treatment plans for individuals with JIA.

FUNDING

Medical Research Council, Versus Arthritis, Great Ormond Street Hospital Children's Charity, Olivia's Vision, and National Institute for Health Research.

Preexisting and de novo humoral immunity to SARS-CoV-2 in humans

Zoonotic introduction of novel coronaviruses may encounter preexisting immunity in humans. Using diverse assays for antibodies recognizing SARS-CoV-2 proteins, we detected preexisting humoral immunity. SARS-CoV-2 spike glycoprotein (S)-reactive antibodies were detectable using a flow cytometry-based method in SARS-CoV-2-uninfected individuals and were particularly prevalent in children and adolescents. They were predominantly of the immunoglobulin G (IgG) class and targeted the S2 subunit. By contrast, SARS-CoV-2 infection induced higher titers of SARS-CoV-2 S-reactive IgG antibodies targeting both the S1 and S2 subunits, and concomitant IgM and IgA antibodies, lasting throughout the observation period. SARS-CoV-2-uninfected donor sera exhibited specific neutralizing activity against SARS-CoV-2 and SARS-CoV-2 S pseudotypes. Distinguishing preexisting and de novo immunity will be critical for our understanding of susceptibility to and the natural course of SARS-CoV-2 infection.

Preexisting and de novo humoral immunity to SARS-CoV-2 in humans

Zoonotic introduction of novel coronaviruses may encounter preexisting immunity in humans. Using diverse assays for antibodies recognizing SARS-CoV-2 proteins, we detected preexisting humoral immunity. SARS-CoV-2 spike glycoprotein (S)-reactive antibodies were detectable using a flow cytometry-based method in SARS-CoV-2-uninfected individuals and were particularly prevalent in children and adolescents. They were predominantly of the immunoglobulin G (IgG) class and targeted the S2 subunit. By contrast, SARS-CoV-2 infection induced higher titers of SARS-CoV-2 S-reactive IgG antibodies targeting both the S1 and S2 subunits, and concomitant IgM and IgA antibodies, lasting throughout the observation period. SARS-CoV-2-uninfected donor sera exhibited specific neutralizing activity against SARS-CoV-2 and SARS-CoV-2 S pseudotypes. Distinguishing preexisting and de novo immunity will be critical for our understanding of susceptibility to and the natural course of SARS-CoV-2 infection.

Male sex identified by global COVID-19 meta-analysis as a risk factor for death and ITU admission

Anecdotal evidence suggests that Coronavirus disease 2019 (COVID-19), caused by the coronavirus SARS-CoV-2, exhibits differences in morbidity and mortality between sexes. Here, we present a meta-analysis of 3,111,714 reported global cases to demonstrate that, whilst there is no difference in the proportion of males and females with confirmed COVID-19, male patients have almost three times the odds of requiring intensive treatment unit (ITU) admission (OR = 2.84; 95% CI = 2.06, 3.92) and higher odds of death (OR = 1.39; 95% CI = 1.31, 1.47) compared to females. With few exceptions, the sex bias observed in COVID-19 is a worldwide phenomenon. An appreciation of how sex is influencing COVID-19 outcomes will have important implications for clinical management and mitigation strategies for this disease.

Male sex identified by global COVID-19 meta-analysis as a risk factor for death and ITU admission

Anecdotal evidence suggests that Coronavirus disease 2019 (COVID-19), caused by the coronavirus SARS-CoV-2, exhibits differences in morbidity and mortality between sexes. Here, we present a meta-analysis of 3,111,714 reported global cases to demonstrate that, whilst there is no difference in the proportion of males and females with confirmed COVID-19, male patients have almost three times the odds of requiring intensive treatment unit (ITU) admission (OR = 2.84; 95% CI = 2.06, 3.92) and higher odds of death (OR = 1.39; 95% CI = 1.31, 1.47) compared to females. With few exceptions, the sex bias observed in COVID-19 is a worldwide phenomenon. An appreciation of how sex is influencing COVID-19 outcomes will have important implications for clinical management and mitigation strategies for this disease.

Male sex identified by global COVID-19 meta-analysis as a risk factor for death and ITU admission

Anecdotal evidence suggests that Coronavirus disease 2019 (COVID-19), caused by the coronavirus SARS-CoV-2, exhibits differences in morbidity and mortality between sexes. Here, we present a meta-analysis of 3,111,714 reported global cases to demonstrate that, whilst there is no difference in the proportion of males and females with confirmed COVID-19, male patients have almost three times the odds of requiring intensive treatment unit (ITU) admission (OR = 2.84; 95% CI = 2.06, 3.92) and higher odds of death (OR = 1.39; 95% CI = 1.31, 1.47) compared to females. With few exceptions, the sex bias observed in COVID-19 is a worldwide phenomenon. An appreciation of how sex is influencing COVID-19 outcomes will have important implications for clinical management and mitigation strategies for this disease.

Comparing Proxy, Adolescent, and Adult Assessments of Functional Ability in Adolescents With Juvenile Idiopathic Arthritis

Objective

In pediatric research, investigators rely on proxy reports of outcome, such as the proxy‐completed Childhood Health Assessment Questionnaire (C‐HAQ), to assess function in juvenile idiopathic arthritis (JIA). As children mature, they may self‐complete the adult HAQ or the unvalidated adolescent‐specific C‐HAQ. It is unclear how these measures compare and whether they are directly interchangeable. The present study was undertaken to compare agreement between the proxy‐completed C‐HAQ, adolescent‐specific C‐HAQ, and the HAQ at initial presentation to pediatric rheumatologic care and 1 year following the first presentation in adolescents with JIA.

Methods

Adolescents ages 11–17 years participating in the Childhood Arthritis Prospective Study (CAPS), a UK multicenter inception cohort, were included. In a CAPS substudy, adolescents self‐completed the adolescent‐specific C‐HAQ and the HAQ, and proxies simultaneously completed the proxy‐completed C‐HAQ at baseline and 1 year. Correlation and agreement between scores were assessed at baseline. Agreement and ability to similarly classify clinically important changes over time were assessed at 1 year following initial presentation to rheumatologic care.

Results

A total of 107 adolescents (adolescent‐specific C‐HAQ and HAQ) or their proxies (proxy‐completed C‐HAQ) had completed all 3 measures at baseline. Median age at diagnosis was 13 years, and 61% were female. Although the 3 scores demonstrated strong correlations (r > 0.8), they were not completely interchangeable, with agreement ranging between 70% and 80%. There was similar agreement between the changes in scores between baseline and 1 year. Using proxy‐completed C‐HAQ minimum clinically important cutoffs, the adolescent‐specific C‐HAQ and the HAQ similarly classified 80% to 90% of adolescents as having improved or worsened.

Conclusion

While there is relatively high agreement and similar classification of change between HAQ and the 2 C‐HAQ scores, these are not completely interchangeable. This impacts the comparison of function when measured in different ways over the lifespan.

Diapedesis-Induced Integrin Signaling via LFA-1 Facilitates Tissue Immunity by Inducing Intrinsic Complement C3 Expression in Immune Cells

Intrinsic complement C3 activity is integral to human T helper type 1 (Th1) and cytotoxic T cell responses. Increased or decreased intracellular C3 results in autoimmunity and infections, respectively. The mechanisms regulating intracellular C3 expression remain undefined. We identified complement, including C3, as among the most significantly enriched biological pathway in tissue-occupying cells. We generated C3-reporter mice and confirmed that C3 expression was a defining feature of tissue-immune cells, including T cells and monocytes, occurred during transendothelial diapedesis, and depended on integrin lymphocyte-function-associated antigen 1 (LFA-1) signals. Immune cells from patients with leukocyte adhesion deficiency type 1 (LAD-1) had reduced C3 transcripts and diminished effector activities, which could be rescued proportionally by intracellular C3 provision. Conversely, increased C3 expression by T cells from arthritis patients correlated with disease severity. Our study defines integrins as key controllers of intracellular complement, demonstrates that perturbations in the LFA-1-C3-axis contribute to primary immunodeficiency, and identifies intracellular C3 as biomarker of severity in autoimmunity.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Microbiota-Derived Metabolites Suppress Arthritis by Amplifying Aryl-Hydrocarbon Receptor Activation in Regulatory B Cells

The differentiation of IL-10-producing regulatory B cells (Bregs) in response to gut-microbiota-derived signals supports the maintenance of tolerance. However, whether microbiota-derived metabolites can modulate Breg suppressive function remains unknown. Here, we demonstrate that rheumatoid arthritis (RA) patients and arthritic mice have a reduction in microbial-derived short-chain fatty acids (SCFAs) compared to healthy controls and that in mice, supplementation with the SCFA butyrate reduces arthritis severity. Butyrate supplementation suppresses arthritis in a Breg-dependent manner by increasing the level of the serotonin-derived metabolite 5-Hydroxyindole-3-acetic acid (5-HIAA), which activates the aryl-hydrocarbon receptor (AhR), a newly discovered transcriptional marker for Breg function. Thus, butyrate supplementation via AhR activation controls a molecular program that supports Breg function while inhibiting germinal center (GC) B cell and plasmablast differentiation. Our study demonstrates that butyrate supplementation may serve as a viable therapy for the amelioration of systemic autoimmune disorders.

O17 Modelling longitudinal patient-reported outcome measures in JDM

Background

Juvenile dermatomyositis (JDM) is a rare autoimmune disease known to primarily cause rash and muscle weakness. The evolution of the disease is still unclear, in particular disease activity based on patient-reported outcomes. A cohort of 493 patients with 3,625 visits up to 5 years since diagnosis was used to explore disease trajectories based on the patient-reported outcome, patient/parent visual analogue scale (VAS), completed by the appropriate person depending on the child’s age. Age at diagnosis, sex, ethnicity and baseline physician's global assessment (PGA) measurements were considered as predictors of disease activity. In addition to this 8 baseline clinical/medical history variables were also considered as potentially predictive: ulcerations, Gottron’s papules, myalgia, fever, fatigue, dysphagia, respiration and gastrointestinal problems.

Methods

A mixed effects model was fitted to the data to identify the strongest predictors of disease activity accounting for correlations of patient/parent VAS measurements within patients. Growth mixture models were used to identify subgroups of patients that shared similar trajectories (latent classes) and logistic regression was used to predict the probability of belonging to the subgroup that had more severe disease activity. The identified latent classes of disease activity, based on the patient-reported outcome of patient/parent VAS, were compared with previously identified latent classes derived from PGA as the outcome measure.

Results

The results from fitting a mixed effects model showed that disease activity had a cubic relationship with time since diagnosis. Being non-white and having a history of myalgia and gastrointestinal problems was shown to predict higher disease activity across the whole follow-up time. The results from fitting growth mixture models led to identifying two classes: the first showed an improvement in condition after the first year, which correlated with results from the mixed effects model, the second, more severe class, was on average higher and showed little improvement across the 5 years. In addition to the predictors identified in the mixed effects model, skin ulceration and older than the mean age (8.3 years) at diagnosis were shown to be associated with the probability of belonging to the more severe class.

Conclusion

Comparing these results to those previously found in analyses of PGA data collected on the same patients, we found that the patterns of activity were similar although on average higher, indicating that reports of disease activity by patients/parents were worse than those collected from physicians. This could be due to factors influencing patient’s experiences that are not measured by physicians. Discussions with clinicians suggest that this could be due to symptoms that are difficult to measure and that are unaffected by treatment, for example, symptoms causing damage. These are often overlooked in physician’s assessments, despite being an important factor for patients.

Disclosures

P.J. Baptiste None. L.R. Wedderburn None. C.T. Deakin None. B.L. De Stavola None. E. Njagi None.

O29 Methotrexate response clusters in JIA

Background

Treatment response in juvenile idiopathic arthritis (JIA) is currently viewed as a binary outcome of response versus non-response. In a heterogenous disease such as JIA, it is likely that different, identifiable clusters of children and young people (CYP) may display varying patterns of the different features of the disease. Identifying these response clusters is an important step toward stratified medicine in JIA. The aim of the study was to explore trajectories of juvenile arthritis disease activity score (JADAS) components following methotrexate (MTX) initiation for JIA.

Methods

MTX-naïve CYP with JIA were selected if enrolled prior to January 2018 in either the UK BSPAR Etanercept Register or the Biologics for Children with Rheumatic Diseases Study at point of starting MTX. JADAS components (active joint count, physician’s global assessment (0-10cm), parental global evaluation (0-10cm) and standardised ESR (0-10) were calculated based on data collected in the year following MTX initiation. Multivariate group-based trajectory models were used to explore MTX response clusters across the different JADAS components, using censored-normal (global scores, ESR) and zero-inflated Poisson (active joint count) models. Optimal models were selected based on a combination of model fit (BIC), parsimony and clinical plausibility.

Results

Of 611 CYP selected, the majority were female (69%) and of white ethnicity (85%), with RF-negative JIA the most common disease category (33%). The optimal model identified multiple patterns of disease activity following initiation of MTX, which have greater complexity than simple ‘response’ versus ‘non-response’ clusters. Differences between clusters included initial intensity of disease features and speeds of improvement over time. In addition, the components of the JADAS did not always follow similar patterns over time, even within the same outcome cluster.

Conclusion

This study has identified that within CYP initiating MTX, different patterns of disease activity are apparent, suggesting that a simple responder/non-responder analysis at a set point may be inadequate. Understanding both clinical factors associated with, and biological mechanisms underpinning, these clusters would aid stratified medicine in JIA.

Disclosures

S.J.W. Shoop-Worrall None. K.L. Hyrich None. L.R. Wedderburn None. W. Thomson None. N. Geifman None.

Being on the juvenile dermatomyositis rollercoaster: a qualitative study

BACKGROUND

Juvenile Dermatomyositis is a rare, potentially life-threatening condition with no known cure. There is no published literature capturing how children and young people feel about their condition, from their perspective. This study was therefore unique in that it asked children and young people what is it like to live with Juvenile Dermatomyositis.

METHODS

Data were obtained from fifteen young people with Juvenile Dermatomyositis, between eight and nineteen years of age from one Paediatric Rheumatology department using audio-recorded interpretive phenomenology interviews. Data were analyzed phenomenologically, using a process that derives narratives from transcripts resulting in a collective composite of participants shared experiences, called a 'phenomenon'.

RESULTS

The overarching metaphor of a rollercoaster captures the phenomenon of living with Juvenile Dermatomyositis as a young person, with the ups and downs at different time points clearly described by those interviewed. The five themes plotted on the rollercoaster, began with confusion; followed by feeling different, being sick, steroidal and scared from the medications; uncertainty; and then ended with acceptance of the disease over time.

CONCLUSION

Young people were able to talk about their experiences about having Juvenile Dermatomyositis. Our findings will aid clinicians in their practice by gaining a deeper understanding of what daily life is like and highlighting ways to enhance psychosocial functioning. Hopefully, this study and any further resulting studies, will raise understanding of Juvenile Dermatomyositis worldwide and will encourage health care professionals to better assess psychosocial needs in the future.

Focused HLA analysis in Caucasians with myositis identifies significant associations with autoantibody subgroups

Objectives

Idiopathic inflammatory myopathies (IIM) are a spectrum of rare autoimmune diseases characterised clinically by muscle weakness and heterogeneous systemic organ involvement. The strongest genetic risk is within the major histocompatibility complex (MHC). Since autoantibody presence defines specific clinical subgroups of IIM, we aimed to correlate serotype and genotype, to identify novel risk variants in the MHC region that co-occur with IIM autoantibodies.

Methods

We collected available autoantibody data in our cohort of 2582 Caucasian patients with IIM. High resolution human leucocyte antigen (HLA) alleles and corresponding amino acid sequences were imputed using SNP2HLA from existing genotyping data and tested for association with 12 autoantibody subgroups.

Results

We report associations with eight autoantibodies reaching our study-wide significance level of p<2.9×10^–5. Associations with the 8.1 ancestral haplotype were found with anti-Jo-1 (HLA-B*08:01, p=2.28×10^–53 and HLA-DRB1*03:01, p=3.25×10^–9), anti-PM/Scl (HLA-DQB1*02:01, p=1.47×10^–26) and anti-cN1A autoantibodies (HLA-DRB1*03:01, p=1.40×10^–11). Associations independent of this haplotype were found with anti-Mi-2 (HLA-DRB1*07:01, p=4.92×10^–13) and anti-HMGCR autoantibodies (HLA-DRB1*11, p=5.09×10^–6). Amino acid positions may be more strongly associated than classical HLA associations; for example with anti-Jo-1 autoantibodies and position 74 of HLA-DRB1 (p=3.47×10^–64) and position 9 of HLA-B (p=7.03×10^–11). We report novel genetic associations with HLA-DQB1 anti-TIF1 autoantibodies and identify haplotypes that may differ between adult-onset and juvenile-onset patients with these autoantibodies.

Conclusions

These findings provide new insights regarding the functional consequences of genetic polymorphisms within the MHC. As autoantibodies in IIM correlate with specific clinical features of disease, understanding genetic risk underlying development of autoantibody profiles has implications for future research.

Development of a benchmarking toolkit for adolescent and young adult rheumatology services (BeTAR)

BACKGROUND

Young people (YP; 12-24 years old) with rheumatic diseases face many challenges associated with chronic illness in addition to the physiological and psychosocial changes of adolescence. Timely access to developmentally appropriate multidisciplinary care is key to successfully managing rheumatic diseases, but gaps in the care of this vulnerable age group still exist. This study aimed to develop a benchmarking toolkit to enable comparative evaluation of YP rheumatology services in order to promote best practice and reduce variations in service delivery.

METHODS

A staged and consultative method was used across a broad group of stakeholders in the UK (YP, parents/other carers, and healthcare professionals, HCPs) to develop this toolkit, with reference to pre-existing standards of YP-friendly healthcare. Eighty-seven YP (median age 19 years, range 12-24 years) and 26 rheumatology HCPs with 1-34 years of experience caring for YP have participated.

RESULTS

Thirty quality criteria were identified, which were grouped into four main domains: assessment and treatment, information and involvement, accessibility and environment, and continuity of care. Two toolkit versions, one to be completed by HCPs and one to be completed by patients, were developed. These were further refined by relevant groups and face validity was confirmed.

CONCLUSIONS

A toolkit has been developed to systematically evaluate and benchmark YP rheumatology services, which is key in setting standards of care, identifying targets for improvement and facilitating research. Engagement from YP, clinical teams, and commissioners with this tool should facilitate investigation of variability in levels of care and drive quality improvement.

Galectin-9 and CXCL10 as Biomarkers for Disease Activity in Juvenile Dermatomyositis: A Longitudinal Cohort Study and Multicohort Validation

Objective

Objective evaluation of disease activity is challenging in patients with juvenile dermatomyositis (DM) due to a lack of reliable biomarkers, but it is crucial to avoid both under‐ and overtreatment of patients. Recently, we identified 2 proteins, galectin‐9 and CXCL10, whose levels are highly correlated with the extent of juvenile DM disease activity. This study was undertaken to validate galectin‐9 and CXCL10 as biomarkers for disease activity in juvenile DM, and to assess their disease specificity and potency in predicting the occurrence of flares.

Methods

Levels of galectin‐9 and CXCL10 were measured by multiplex immunoassay in serum samples from 125 unique patients with juvenile DM in 3 international cross‐sectional cohorts and a local longitudinal cohort. The disease specificity of both proteins was examined in 50 adult patients with DM or nonspecific myositis (NSM) and 61 patients with other systemic autoimmune diseases.

Results

Both cross‐sectionally and longitudinally, galectin‐9 and CXCL10 outperformed the currently used laboratory marker, creatine kinase (CK), in distinguishing between juvenile DM patients with active disease and those in remission (area under the receiver operating characteristic curve [AUC] 0.86–0.90 for galectin‐9 and CXCL10; AUC 0.66–0.68 for CK). The sensitivity and specificity for active disease in juvenile DM was 0.84 and 0.92, respectively, for galectin‐9 and 0.87 and 1.00, respectively, for CXCL10. In 10 patients with juvenile DM who experienced a flare and were prospectively followed up, continuously elevated or rising biomarker levels suggested an imminent flare up to several months before the onset of symptoms, even in the absence of elevated CK levels. Galectin‐9 and CXCL10 distinguished between active disease and remission in adult patients with DM or NSM (P = 0.0126 for galectin‐9 and P < 0.0001 for CXCL10) and were suited for measurement in minimally invasive dried blood spots (healthy controls versus juvenile DM, P = 0.0040 for galectin‐9 and P < 0.0001 for CXCL10).

Conclusion

In this study, galectin‐9 and CXCL10 were validated as sensitive and reliable biomarkers for disease activity in juvenile DM. Implementation of these biomarkers into clinical practice as tools to monitor disease activity and guide treatment might facilitate personalized treatment strategies.

Histological heterogeneity in a large clinical cohort of juvenile idiopathic inflammatory myopathy: analysis by myositis autoantibody and pathological features

Aim

Juvenile idiopathic inflammatory myopathies have been recently reclassified into clinico‐serological subgroups. Myopathological correlates of the subgroups are incompletely understood.

Methods

We studied muscle biopsies from 101 children with clinically and serologically defined juvenile idiopathic inflammatory myopathies from the UK JDM Cohort and Biomarker Study by applying the international JDM score tool, myopathological review and C5b‐9 complement analysis.

Results

Autoantibody data were available for 90/101 cases with 18/90 cases positive for anti‐TIF1γ, 15/90 anti‐NXP2, 11/90 anti‐MDA5, 5/90 anti‐Mi2 and 6/90 anti‐PmScl. JDM biopsy severity scores were consistently low in the anti‐MDA5 group, high in the anti‐Mi2 group, and widely distributed in the other groups. Biopsies were classified histologically as perifascicular atrophy (22/101), macrophage‐rich necrosis (6/101), scattered necrosis (2/101), clustered necrosis (2/101), inflammatory fibre invasion (2/101), chronic myopathic change (1/101), diffuse endomysial macrophage infiltrates (40/101) and minimal change (24/101). MDA5 cases segregated with the minimal change group and showed no capillary C5b‐9‐deposition. The Mi2 group displayed high severity scores and a tendency towards sarcolemmal complement deposition. NXP2 and TIF1γ groups showed a variety of pathologies with a high proportion of diffuse endomysial macrophage infiltrates and a high proportion of capillary C5b‐9 deposition.

Conclusion

We have shown that juvenile idiopathic inflammatory myopathies have a spectrum of histopathological phenotypes and show distinct complement attack complex deposition patterns. Both correlate in some cases with the serological subtypes. Most cases do not show typical histological features associated with dermatomyositis (e.g. perifascicular atrophy). In contrast, more than half show relatively mild histopathological changes.

Innate Lymphoid Cells and T Cells Contribute to the Interleukin-17A Signature Detected in the Synovial Fluid of Patients With Juvenile Idiopathic Arthritis

OBJECTIVE

Evidence suggests that aberrant function of innate lymphoid cells (ILCs), whose functional and transcriptional profiles overlap with those of Th cell subsets, contributes to immune-mediated pathologies. To date, analysis of juvenile idiopathic arthritis (JIA) immune pathology has concentrated on the contribution of CD4+ T cells; we have previously identified an expansion of Th17 cells within the synovial fluid (SF) of JIA patients. We undertook this study to extend this analysis to further investigate the role of ILCs and other interleukin-17 (IL-17)-producing T cell subsets in JIA.

METHODS

ILCs and CD3+ T cell subsets were defined in peripheral blood mononuclear cells (PBMCs) from healthy adults, healthy children, and JIA patients and in SF mononuclear cells (SFMCs) from JIA patients using flow cytometry. Defined subsets in SFMCs were correlated with clinical measures including physician's global assessment of disease activity on a visual analog scale, number of joints with active disease, and erythrocyte sedimentation rate. Transcription factor and cytokine profiles of sorted ILCs were assessed by quantitative reverse transcriptase-polymerase chain reaction.

RESULTS

Group 1 ILCs (ILC1s), NKp44- group 3 ILCs (natural cytotoxicity receptor-negative [NCR-] ILC3s), and NKp44+ ILC3s (NCR+ ILC3s) were enriched in JIA SFMCs compared to PBMCs, which corresponded to an increase in transcripts for TBX21, IFNG, and IL17A. Of the ILC subsets, the frequency of NCR- ILC3s in JIA SFMCs displayed the strongest positive association with clinical measures, which was mirrored by an expansion in IL-17A+CD4+, IL-17A+CD8+, and IL-17A+ γδ T cells.

CONCLUSION

We demonstrate that the strength of the IL-17A signature in JIA SFMCs is determined by multiple lymphoid cell types, including NCR- ILC3s and IL-17A+CD4+, IL-17A+CD8+, and IL-17A+ γδ T cells. These observations may have important implications for the development of stratified therapeutics.

Sex and Pubertal Differences in the Type 1 Interferon Pathway Associate With Both X Chromosome Number and Serum Sex Hormone Concentration

Type 1 interferons (IFN) are an antiviral cytokine family, important in juvenile onset systemic lupus erythematosus (jSLE) which is more common in females, around puberty. We report that plasmacytoid dendritic cells (pDC) from healthy females produced more type 1 IFN after toll like receptor (TLR) 7 signaling than males, even before puberty, but that puberty itself associated with increased production of type 1 IFN. A unique human model allows us to show that this was related to X chromosome number, and serum testosterone concentration, in a manner which differed depending on the number of X chromosomes present. In addition, we have showed that pDC were more activated in females overall, and immune cell TLR7 gene expression was higher in females after puberty. Therefore, sex hormones and X chromosome number were associated individually and interactively with the type 1 IFN response, which contributes to our understanding of why females are more likely to develop an IFN mediated disease like jSLE after puberty.