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.

Association with HLA-DRß1 position 37 distinguishes juvenile dermatomyositis from adult-onset myositis.

Juvenile dermatomyositis (JDM) is a rare, severe autoimmune disease and the most common idiopathic inflammatory myopathy of children. JDM and adult-onset dermatomyositis (DM) have similar clinical, biological and serological features, although these features differ in prevalence between childhood-onset and adult-onset disease, suggesting that age of disease onset may influence pathogenesis. Therefore, a JDM-focused genetic analysis was performed using the largest collection of JDM samples to date. Caucasian JDM samples (n = 952) obtained via international collaboration were genotyped using the Illumina HumanCoreExome chip. Additional non-assayed human leukocyte antigen (HLA) loci and genome-wide single-nucleotide polymorphisms (SNPs) were imputed. HLA-DRB1*03:01 was confirmed as the classical HLA allele most strongly associated with JDM [odds ratio (OR) 1.66; 95% confidence interval (CI) 1.46, 1.89; P = 1.4 × 10-14], with an independent association at HLA-C*02:02 (OR = 1.74; 95% CI 1.42, 2.13, P = 7.13 × 10-8). Analyses of amino acid positions within HLA-DRB1 indicated that the strongest association was at position 37 (omnibus P = 3.3 × 10-19), with suggestive evidence this association was independent of position 74 (omnibus P = 5.1 × 10-5), the position most strongly associated with adult-onset DM. Conditional analyses also suggested that the association at position 37 of HLA-DRB1 was independent of some alleles of the Caucasian HLA 8.1 ancestral haplotype (AH8.1) such as HLA-DQB1*02:01 (OR = 1.62; 95% CI 1.36, 1.93; P = 8.70 × 10-8), but not HLA-DRB1*03:01 (OR = 1.49; 95% CR 1.24, 1.80; P = 2.24 × 10-5). No associations outside the HLA region were identified. Our findings confirm previous associations with AH8.1 and HLA-DRB1*03:01, HLA-C*02:02 and identify a novel association with amino acid position 37 within HLA-DRB1, which may distinguish JDM from adult DM.

Economic evaluation of a trial exploring the effects of a web-based support tool for parents of children with juvenile idiopathic arthritis.

OBJECTIVE: To explore the cost-effectiveness of a web-based support tool for parents of children with Juvenile Idiopathic Arthritis. METHODS: A multi-centred randomised controlled trial was conducted in paediatric rheumatology centres in England. The WebParC intervention consisted of online information about JIA and its treatment and a toolkit using cognitive-behavioural therapy principles to support parents manage their child's JIA. An economic evaluation was performed alongside the trial involving 220 parents. The primary outcome was the self-report Pediatric Inventory for Parents measure of illness-related parenting stress, with two dimensions; difficulty and frequency. These measures along with costs were assessed post intervention at 4 months and 12 months. Costs were calculated for healthcare usage using a UK NHS economic perspective. Data was collected and analysed on the impact of caring costs on families. Uncertainty around cost effectiveness was explored using bootstrapping and cost-effectiveness acceptability curves. RESULTS: The intervention arm showed improved average Pediatric Inventory for Parents scores for the dimensions of frequency and difficulty, of 1.5 and 3.6 respectively at 4 months and. 0.35 and 0.39 at 12 months, representing improved PIP scores for the intervention arm. At both 4 and 12 month follow up the average total cost per case was higher in the control group when compared with the intervention arm with mean differences of £360 (95% CI £29.6 to £691) at 4 months and £203 (95% CI £16 to £390) at 12 months. The probability of the intervention being cost effective ranged between 49% and 54%. CONCLUSION: The WebParC intervention led to reductions in primary and secondary healthcare resource use and costs at 4 and 12 months. The intervention demonstrated particular savings for rheumatology services at both follow ups. Future economies of scale could be realised by health providers with increased opportunities for cost effectiveness over time. TRIAL REGISTRATION: ISRCTN, ISRCTN13159730.

Towards molecular-pathology informed clinical trials in childhood arthritis to achieve precision medicine in juvenile idiopathic arthritis.

In childhood arthritis, collectively known as Juvenile idiopathic arthritis (JIA), the rapid rise of available licensed biological and targeted small molecule treatments in recent years has led to improved outcomes. However, real-world data from multiple countries and registries show that despite a large number of available drugs, many children and young people continue to suffer flares and experience significant periods of time with active disease for many years. More than 50% of young people with JIA require ongoing immune suppression well into adult life, and they may have to try multiple different treatments in that time. There are currently no validated tools with which to select specific treatments, nor biomarkers of response to assist in such choices, therefore, current management uses essentially a trial-and-error approach. A further consequence of recent progress is a reducing pool of available children or young people who are eligible for new trials. In this review we consider how progress towards a molecular based approach to defining treatment targets and informing trial design in JIA, combined with novel approaches to clinical trials, could provide strategies to maximise discovery and progress, in order to move towards precision medicine for children with arthritis.

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

OBJECTIVES: To define the host mechanisms contributing to the pathological interferon (IFN) type 1 signature in Juvenile dermatomyositis (JDM). METHODS: RNA-sequencing was performed on CD4+, CD8+, CD14+ and CD19+ cells sorted from pretreatment and on-treatment JDM (pretreatment n=10, on-treatment n=11) and age/sex-matched child healthy-control (CHC n=4) peripheral blood mononuclear cell (PBMC). Mitochondrial morphology and superoxide were assessed by fluorescence microscopy, cellular metabolism by 13C glucose uptake assays, and oxidised mitochondrial DNA (oxmtDNA) content by dot-blot. Healthy-control PBMC and JDM pretreatment PBMC were cultured with IFN-α, oxmtDNA, cGAS-inhibitor, TLR-9 antagonist and/or n-acetyl cysteine (NAC). IFN-stimulated gene (ISGs) expression was measured by qPCR. Total numbers of patient and controls for functional experiments, JDM n=82, total CHC n=35. RESULTS: Dysregulated mitochondrial-associated gene expression correlated with increased ISG expression in JDM CD14+ monocytes. Altered mitochondrial-associated gene expression was paralleled by altered mitochondrial biology, including 'megamitochondria', cellular metabolism and a decrease in gene expression of superoxide dismutase (SOD)1. This was associated with enhanced production of oxidised mitochondrial (oxmt)DNA. OxmtDNA induced ISG expression in healthy PBMC, which was blocked by targeting oxidative stress and intracellular nucleic acid sensing pathways. Complementary experiments showed that, under in vitro experimental conditions, targeting these pathways via the antioxidant drug NAC, TLR9 antagonist and to a lesser extent cGAS-inhibitor, suppressed ISG expression in pretreatment JDM PBMC. CONCLUSIONS: These results describe a novel pathway where altered mitochondrial biology in JDM CD14+ monocytes lead to oxmtDNA production and stimulates ISG expression. Targeting this pathway has therapeutical potential in JDM and other IFN type 1-driven autoimmune diseases.

The impact of psoriasis on wellbeing and clinical outcomes in juvenile psoriatic arthritis.

OBJECTIVES: Juvenile psoriatic arthritis (JPsA) has varied clinical features that are distinctive to other juvenile idiopathic arthritis (JIA) categories. This study investigates whether such features impact patient-reported and clinical outcomes. METHODS: Children and young people (CYP) were selected if recruited to the Childhood Arthritis Prospective Study, a UK multicentre JIA inception cohort, between January 2001 and March 2018. At diagnosis, patient/parent-reported outcomes (as age-appropriate) included the parental global assessment (10 cm VAS), functional ability (CHAQ), pain (10 cm VAS), health-related quality of life (CHQ psychosocial score), mood/depressive symptoms (MFQ) and parent psychosocial health (GHQ). Three-year outcome trajectories have previously been defined using active joint counts, physician and parent global assessments (PGA, PaGA respectively). Patient-reported outcomes and outcome trajectories were compared in i) CYP with JPsA versus other JIA categories, ii) CYP within JPsA, with and without psoriasis via multivariable linear regression. RESULTS: There were no significant differences in patient-reported outcomes at diagnosis between CYP with JPsA and non-JPsA. Within JPsA, those with psoriasis had more depressive symptoms (coefficient = 9.8, 95% CI = 0.5-19.0) than those without psoriasis at diagnosis. CYP with JPsA had 2.3 times the odds of persistent high PaGA than other ILAR categories, despite improving joint counts and PGA (95% CI 1.2, 4.6). CONCLUSION: CYP with psoriasis at JPsA diagnosis report worse mood, supporting a greater disease impact in those with both skin and joint involvement. Multidisciplinary care with added focus to support wellbeing in children with JPsA plus psoriasis may help improve these outcomes.

Comparison of clinical features between patients with anti-synthetase syndrome and dermatomyositis: Results from the MYONET registry.

OBJECTIVES: To compare clinical characteristics, including the frequency of cutaneous, extramuscular manifestations, and malignancy, between adults with anti-synthetase syndrome (ASyS) and dermatomyositis (DM). METHODS: Using data regarding adults from the MYONET registry, a cohort of DM patients with anti-Mi2/-TIF1É£/-NXP2/-SAE/-MDA5 autoantibodies, and a cohort of ASyS patients with anti-tRNA synthetase autoantibodies (anti-Jo1/-PL7/-PL12/-OJ/-EJ/-Zo/-KS) were identified. Patients with DM sine dermatitis or with discordant dual autoantibody specificities were excluded. Sub-cohorts of patients with ASyS with or without skin involvement were defined based on presence of DM-type rashes (heliotrope rash, Gottron's papules/sign, violaceous rash, shawl sign, V sign, erythroderma, and/or periorbital rash). RESULTS: In total 1,054 patients were included (DM, n = 405; ASyS, n = 649). In ASyS cohort, 31% (n = 203) had DM-type skin involvement (ASyS-DMskin). A higher frequency of extramuscular manifestations, including Mechanic's hands, Raynaud's phenomenon, arthritis, interstitial lung disease, and cardiac involvement differentiated ASyS-DMskin from DM (all p< 0.001), whereas higher frequency of any of four DM-type rashes: heliotrope rash (n = 248, 61% vs n = 90, 44%), violaceous rash (n = 166, 41% vs n = 57, 9%), V sign (n = 124, 31% vs n = 28, 4%), and shawl sign (n = 133, 33% vs n = 18, 3%) differentiated DM from ASyS-DMskin (all p< 0.005). Cancer-associated myositis (CAM) was more frequent in DM (n = 67, 17%) compared with ASyS (n = 21, 3%) and ASyS-DMskin (n = 7, 3%) cohorts (both p< 0.001). CONCLUSION: DM-type rashes are frequent in patients with ASyS; however, distinct clinical manifestations differentiate these patients from classical DM. Skin involvement in ASyS does not necessitate increased malignancy surveillance. These findings will inform future ASyS classification criteria and patient management.

Juvenile dermatomyositis. Where are we now?

Juvenile onset idiopathic inflammatory myopathy (IIM) has many similarities and distinct differences from adult-onset disease. This review will focus on recent developments in understanding and treatment of juvenile dermatomyositis (JDM), the most common disease sub-type of IIM in childhood. JDM is a systemic immune mediated vasculopathy, increasingly recognised as a group of distinct phenotypes with variable presentation and outlook. This overview will describe long-term outlook and disease course including health-related quality of life and emerging treatments.

The Effects of a Web-Based Tool for Parents of Children With Juvenile Idiopathic Arthritis: Randomized Controlled Trial.

BACKGROUND: Juvenile idiopathic arthritis (JIA) is a group of autoinflammatory diseases that cause pain and disability if not controlled by treatment. Parenting a child with JIA is stressful for parents, who express concerns about their child's treatment and may experience anxiety and powerlessness concerning their child's illness. Parenting stress is greater in parents of children with chronic illness than in those with healthy children and is related to poorer psychological adjustment in both parents and children. It is therefore important to develop interventions to support parents. This paper reports the evaluation of a web-based tool that provides information and practical skills to help increase parents' confidence in managing their child's illness and reduce parenting stress. OBJECTIVE: The aim of this study is to evaluate the benefits of a web-based tool (WebParC) for parents of children with recently diagnosed JIA. METHODS: A multicentered randomized controlled trial was conducted at pediatric rheumatology centers in England. We recruited parents of children aged ≤12 years who had been diagnosed with JIA within the previous 6 months. They were randomized to the intervention (WebParC access plus standard care) or the control (standard care alone) and followed up 4 months and 12 months after randomization. Where both parents participated, they were randomized by household to the same trial arm. The WebParC intervention consists of information about JIA and its treatment plus a toolkit, based on cognitive behavioral therapy, to help parents develop skills to manage JIA-related issues. The primary outcome was the self-report Pediatric Inventory for Parents measure of illness-related parenting stress. The secondary outcomes were parental mood, self-efficacy, coping, effectiveness of participation in their child's health care, satisfaction with health care, and child's health-related quality of life. RESULTS: A total of 203 households comprising 220 parents were randomized to the intervention (100/203, 49.3%) or control (103/203, 50.7%) arm. Follow-up assessments were completed by 65.5% (133/203) of the households at 4 months (intervention 60/100, 60%, and control 73/103, 70.9%) and 61.1% (124/203) of the households at 12 months (intervention 58/100, 58%, and control 66/103, 64.1%). A main effect of the trial arm was found on the Pediatric Inventory for Parents: the intervention participants reported less frequency (subscales communication F1,120627=5.37; P=.02, and role function F1,27203=5.40; P=.02) and difficulty (subscales communication F1,2237=7.43; P=.006, medical care F1,2907=4.04; P=.04, and role function F1,821=4.37, P=.04) regarding illness-related stressful events than the control participants. CONCLUSIONS: The WebParC website for parents of children with JIA reduced illness-related parenting stress. This web-based intervention offers a feasible preventive approach for parents of children with JIA and potentially could be adapted and evaluated for parents of children with other chronic illnesses. TRIAL REGISTRATION: International Standard Randomized Controlled Trial Number (ISRCTN) 13159730; http://www.isrctn.com/ISRCTN13159730.

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.

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.

Dynamic Lycra® orthoses as an adjunct to arm rehabilitation after stroke: a single-blind, two-arm parallel group, randomized controlled feasibility trial.

OBJECTIVE: The aim of this study was to explore the feasibility of conducting a randomized controlled trial of dynamic Lycra® orthoses as an adjunct to arm rehabilitation after stroke and to explore the magnitude and direction of change on arm outcomes. DESIGN: This is a single-blind, two-arm parallel group, feasibility randomized controlled trial. SETTING: In-patient rehabilitation. SUBJECTS: The study participants were stroke survivors with arm hemiparesis two to four weeks after stroke receiving in-patient rehabilitation. INTERVENTIONS: Participants were randomized 2:1 to wear Lycra® gauntlets for eight hours daily for eight weeks, plus usual rehabilitation (n = 27), or to usual rehabilitation only (n = 16). MAIN MEASURES: Recruitment, retention, fidelity, adverse events and completeness of data collection were examined at 8 and 16 weeks; arm function (activity limitation; Action Research Arm Test, Motor Activity Log) and impairment (Nine-hole Peg Test, Motricity Index, Modified Tardieu Scale). Structured interviews explored acceptability. RESULTS: Of the target of 51, 43 (84%) participants were recruited. Retention at 8 weeks was 32 (79%) and 24 (56%) at 16 weeks. In total, 11 (52%) intervention group participants and 6 (50%) control group participants (odds ratio = 1.3, 95% confidence interval = 0.2 to 7.8) had improved Action Research Arm Test level by 8 weeks; at 16 weeks, this was 8 (61%) intervention and 6 (75.0%) control participants (odds ratio = 1.1, 95% confidence interval = 0.1 to 13.1). Change on other measures favoured control participants. Acceptability was influenced by 26 adverse reactions. CONCLUSION: Recruitment and retention were low, and adverse reactions were problematic. There were no indications of clinically relevant effects, but the small sample means definitive conclusions cannot be made. A definitive trial is not warranted without orthoses adaptation.

Juvenile dermatomyositis: novel treatment approaches and outcomes.

PURPOSE OF REVIEW: The aim of this article is to provide a summary of the recent therapeutic advances and the latest research on outcome measures for juvenile dermatomyositis (JDM). RECENT FINDINGS: Several new international studies have developed consensus-based guidelines on diagnosis, outcome measures and treatment of JDM to standardize and improve patient care. Myositis-specific antibodies together with muscle biopsy histopathology may help the clinician to predict disease outcome. A newly developed MRI-based scoring system has been developed to standardize the use of MRI in assessing disease activity in JDM. New data regarding the efficacy and safety of rituximab, especially for skin disease, and cyclophosphamide in JDM support the use of these medications for severe refractory cases. SUMMARY: International network studies, new biomarkers and outcome measures have led to significant progress in understanding and managing the rare inflammatory myositis conditions such as JDM.

Development of a consensus core dataset in juvenile dermatomyositis for clinical use to inform research.

OBJECTIVES: This study aimed to develop consensus on an internationally agreed dataset for juvenile dermatomyositis (JDM), designed for clinical use, to enhance collaborative research and allow integration of data between centres. METHODS: A prototype dataset was developed through a formal process that included analysing items within existing databases of patients with idiopathic inflammatory myopathies. This template was used to aid a structured multistage consensus process. Exploiting Delphi methodology, two web-based questionnaires were distributed to healthcare professionals caring for patients with JDM identified through email distribution lists of international paediatric rheumatology and myositis research groups. A separate questionnaire was sent to parents of children with JDM and patients with JDM, identified through established research networks and patient support groups. The results of these parallel processes informed a face-to-face nominal group consensus meeting of international myositis experts, tasked with defining the content of the dataset. This developed dataset was tested in routine clinical practice before review and finalisation. RESULTS: A dataset containing 123 items was formulated with an accompanying glossary. Demographic and diagnostic data are contained within form A collected at baseline visit only, disease activity measures are included within form B collected at every visit and disease damage items within form C collected at baseline and annual visits thereafter. CONCLUSIONS: Through a robust international process, a consensus dataset for JDM has been formulated that can capture disease activity and damage over time. This dataset can be incorporated into national and international collaborative efforts, including existing clinical research databases.

The EuroMyositis registry: an international collaborative tool to facilitate myositis research.

AIMS: The EuroMyositis Registry facilitates collaboration across the idiopathic inflammatory myopathy (IIM) research community. This inaugural report examines pooled Registry data. METHODS: Cross-sectional analysis of IIM cases from 11 countries was performed. Associations between clinical subtypes, extramuscular involvement, environmental exposures and medications were investigated. RESULTS: Of 3067 IIM cases, 69% were female. The most common IIM subtype was dermatomyositis (DM) (31%). Smoking was more frequent in connective tissue disease overlap cases (45%, OR 1.44, 95% CI 1.09 to 1.90, p=0.012). Smoking was associated with interstitial lung disease (ILD) (OR 1.32, 95% CI 1.06 to 1.65, p=0.013), dysphagia (OR 1.43, 95% CI 1.16 to 1.77, p=0.001), malignancy ever (OR 1.78, 95% CI 1.36 to 2.33, p<0.001) and cardiac involvement (OR 2.40, 95% CI 1.60 to 3.60, p<0.001).Dysphagia occurred in 39% and cardiac involvement in 9%; either occurrence was associated with higher Health Assessment Questionnaire (HAQ) scores (adjusted OR 1.79, 95% CI 1.43 to 2.23, p<0.001). HAQ scores were also higher in inclusion body myositis cases (adjusted OR 3.85, 95% CI 2.52 to 5.90, p<0.001). Malignancy (ever) occurred in 13%, most commonly in DM (20%, OR 2.06, 95% CI 1.65 to 2.57, p<0.001).ILD occurred in 30%, most frequently in antisynthetase syndrome (71%, OR 10.7, 95% CI 8.6 to 13.4, p<0.001). Rash characteristics differed between adult-onset and juvenile-onset DM cases ('V' sign: 56% DM vs 16% juvenile-DM, OR 0.16, 95% CI 0.07 to 0.36, p<0.001). Glucocorticoids were used in 98% of cases, methotrexate in 71% and azathioprine in 51%. CONCLUSION: This large multicentre cohort demonstrates the importance of extramuscular involvement in patients with IIM, its association with smoking and its influence on disease severity. Our findings emphasise that IIM is a multisystem inflammatory disease and will help inform prognosis and clinical management of patients.

Depressive symptoms, pain and disability for adolescent patients with juvenile idiopathic arthritis: results from the Childhood Arthritis Prospective Study.

Objectives: To determine if depressive symptoms assessed near diagnosis associate with future measures of pain, disability and disease for adolescent patients diagnosed with JIA. Methods: Data were analysed from JIA patients aged 11-16 years recruited to the Childhood Arthritis Prospective Study, a UK-based inception cohort of childhood-onset arthritis. Depressive symptoms (using the Mood and Feelings Questionnaire; MFQ), active and limited joint count, disability score (Childhood Health Assessment Questionnaire), pain visual analogue scale and patient's general evaluation visual analogue scale were collected. Associations between baseline measures (first visit to paediatric rheumatologist) were analysed using multiple linear regression. Linear mixed-effect models for change in the clinical measures of disease over 48 months were estimated including MFQ as an explanatory variable. Results: Data from 102 patients were analysed. At baseline, median (IQR) age was 13.2 years (11.9-14.2 years) and 14.7% scored over the MFQ cut-off for major depressive disorder. At baseline, depressive symptoms significantly associated with all clinical measures of disease (P ⩽ 0.01). High baseline depressive symptoms scores predicted worse pain (P ⩽ 0.005) and disability (P ⩽ 0.001) 12 months later but not active and limited joint counts. Conclusions: Adolescent patients with JIA and depressive symptoms had more active joints, pain and disability at the time of their first specialist appointment. The associations between baseline depression and both pain and disability continued for at least one year, however, this was not the case for active joint count.

A Bayesian semiparametric Markov regression model for juvenile dermatomyositis.

Juvenile dermatomyositis (JDM) is a rare autoimmune disease that may lead to serious complications, even to death. We develop a 2-state Markov regression model in a Bayesian framework to characterise disease progression in JDM over time and gain a better understanding of the factors influencing disease risk. The transition probabilities between disease and remission state (and vice versa) are a function of time-homogeneous and time-varying covariates. These latter types of covariates are introduced in the model through a latent health state function, which describes patient-specific health over time and accounts for variability among patients. We assume a nonparametric prior based on the Dirichlet process to model the health state function and the baseline transition intensities between disease and remission state and vice versa. The Dirichlet process induces a clustering of the patients in homogeneous risk groups. To highlight clinical variables that most affect the transition probabilities, we perform variable selection using spike and slab prior distributions. Posterior inference is performed through Markov chain Monte Carlo methods. Data were made available from the UK JDM Cohort and Biomarker Study and Repository, hosted at the UCL Institute of Child Health.

HLA-DRB1*11 and variants of the MHC class II locus are strong risk factors for systemic juvenile idiopathic arthritis.

Systemic juvenile idiopathic arthritis (sJIA) is an often severe, potentially life-threatening childhood inflammatory disease, the pathophysiology of which is poorly understood. To determine whether genetic variation within the MHC locus on chromosome 6 influences sJIA susceptibility, we performed an association study of 982 children with sJIA and 8,010 healthy control subjects from nine countries. Using meta-analysis of directly observed and imputed SNP genotypes and imputed classic HLA types, we identified the MHC locus as a bona fide susceptibility locus with effects on sJIA risk that transcended geographically defined strata. The strongest sJIA-associated SNP, rs151043342 [P = 2.8 × 10(-17), odds ratio (OR) 2.6 (2.1, 3.3)], was part of a cluster of 482 sJIA-associated SNPs that spanned a 400-kb region and included the class II HLA region. Conditional analysis controlling for the effect of rs151043342 found that rs12722051 independently influenced sJIA risk [P = 1.0 × 10(-5), OR 0.7 (0.6, 0.8)]. Meta-analysis of imputed classic HLA-type associations in six study populations of Western European ancestry revealed that HLA-DRB1*11 and its defining amino acid residue, glutamate 58, were strongly associated with sJIA [P = 2.7 × 10(-16), OR 2.3 (1.9, 2.8)], as was the HLA-DRB1*11-HLA-DQA1*05-HLA-DQB1*03 haplotype [6.4 × 10(-17), OR 2.3 (1.9, 2.9)]. By examining the MHC locus in the largest collection of sJIA patients assembled to date, this study solidifies the relationship between the class II HLA region and sJIA, implicating adaptive immune molecules in the pathogenesis of sJIA.