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.

Artificial intelligence for nailfold capillaroscopy analyses - a proof of concept application in juvenile dermatomyositis.

BACKGROUND: Biomarkers for idiopathic inflammatory myopathies are difficult to identify and may involve expensive laboratory tests. We assess the potential for artificial intelligence (AI) to differentiate children with juvenile dermatomyositis (JDM) from healthy controls using nailfold capillaroscopy (NFC) images. We also assessed the potential of NFC images to reflect the range of disease activity with JDM. METHODS: A total of 1,120 NFC images from 111 children with active JDM, diagnosed between 1990 and 2020, and 321 NFC images from 31 healthy controls were retrieved from the CureJM JDM Registry. We built a lightweight and explainable deep neural network model called NFC-Net. Images were downscaled by interpolation techniques to reduce the computational cost. RESULTS: NFC-Net achieved high performance in differentiating patients with JDM from controls, with an area under the ROC curve (AUROC) of 0.93 (0.84, 0.99) and accuracy of 0.91 (0.82, 0.92). With sensitivity (0.85) and specificity (0.90) resulted in model precision of 0.95. The AUROC and accuracy for predicting clinical disease activity from inactivity were 0.75 (0.61, 0.81) and 0.74 (0.65, 0.79). CONCLUSION: The good performance of the NFC-Net demonstrates that NFC images are sufficient for detecting often unrecognized JDM disease activity, providing a reliable indicator of disease status. IMPACT: Proposed NFC-Net can accurately predict children with JDM from healthy controls using nailfold capillaroscopy (NFC) images. Additionally, it predicts the scores to JDM disease activity versus no activity. Equipped with gradients, NFC-Net is explainable and gives visual information beside the reported accuracies. NFC-Net is computationally efficient since it is applied to substantially downscaled NFC images. Furthermore, the model can be wrapped within an edge-based device like a mobile application that is accessible to both clinicians and patients.

Low copy numbers of complement C4 and C4A deficiency are risk factors for myositis, its subgroups and autoantibodies.

BACKGROUND: Idiopathic inflammatory myopathies (IIM) are a group of autoimmune diseases characterised by myositis-related autoantibodies plus infiltration of leucocytes into muscles and/or the skin, leading to the destruction of blood vessels and muscle fibres, chronic weakness and fatigue. While complement-mediated destruction of capillary endothelia is implicated in paediatric and adult dermatomyositis, the complex diversity of complement C4 in IIM pathology was unknown. METHODS: We elucidated the gene copy number (GCN) variations of total C4, C4A and C4B, long and short genes in 1644 Caucasian patients with IIM, plus 3526 matched healthy controls using real-time PCR or Southern blot analyses. Plasma complement levels were determined by single radial immunodiffusion. RESULTS: The large study populations helped establish the distribution patterns of various C4 GCN groups. Low GCNs of C4T (C4T=2+3) and C4A deficiency (C4A=0+1) were strongly correlated with increased risk of IIM with OR equalled to 2.58 (2.28-2.91), p=5.0×10-53 for C4T, and 2.82 (2.48-3.21), p=7.0×10-57 for C4A deficiency. Contingency and regression analyses showed that among patients with C4A deficiency, the presence of HLA-DR3 became insignificant as a risk factor in IIM except for inclusion body myositis (IBM), by which 98.2% had HLA-DR3 with an OR of 11.02 (1.44-84.4). Intragroup analyses of patients with IIM for C4 protein levels and IIM-related autoantibodies showed that those with anti-Jo-1 or with anti-PM/Scl had significantly lower C4 plasma concentrations than those without these autoantibodies. CONCLUSIONS: C4A deficiency is relevant in dermatomyositis, HLA-DRB1*03 is important in IBM and both C4A deficiency and HLA-DRB1*03 contribute interactively to risk of polymyositis.

Role of mitochondria in the myopathy of juvenile dermatomyositis and implications for skeletal muscle calcinosis.

OBJECTIVES: To elucidate mechanisms contributing to skeletal muscle calcinosis in patients with juvenile dermatomyositis. METHODS: A well-characterized cohorts of JDM (n = 68), disease controls (polymyositis, n = 7; juvenile SLE, n = 10, and RNP + overlap syndrome, n = 12), and age-matched health controls (n = 17) were analyzed for circulating levels of mitochondrial (mt) markers including mtDNA, mt-nd6, and anti-mitochondrial antibodies (AMAs) using standard qPCR, ELISA, and novel-in-house assays, respectively. Mitochondrial calcification of affected tissue biopsies was confirmed using electron microscopy and energy dispersive X-ray analysis. A human skeletal muscle cell line, RH30, was used to generate an in vitro calcification model. Intracellular calcification is measured by flow cytometry and microscopy. Mitochondria were assessed for mtROS production and membrane potential by flow cytometry and real-time oxygen consumption rate by Seahorse bioanalyzer. Inflammation (interferon-stimulated genes) was measured by qPCR. RESULTS: In the current study, patients with JDM exhibited elevated levels of mitochondrial markers associated with muscle damage and calcinosis. Of particular interest are AMAs predictive of calcinosis. Human skeletal muscle cells undergo time- and dose-dependent accumulation of calcium phosphate salts with preferential localization to mitochondria. Calcification renders skeletal muscle cells mitochondria stressed, dysfunctional, destabilized, and interferogenic. Further, we report that inflammation induced by interferon-alpha amplifies mitochondrial calcification of human skeletal muscle cells via the generation of mitochondrial reactive oxygen species (mtROS). CONCLUSIONS: Overall, our study demonstrates the mitochondrial involvement in the skeletal muscle pathology and calcinosis of JDM and mtROS as a central player in the calcification of human skeletal muscle cells. Therapeutic targeting of mtROS and/or upstream inducers, such as inflammation, may alleviate mitochondrial dysfunction, leading to calcinosis. AMAs can potentially identify patients with JDM at risk for developing calcinosis.

The emerging role of Growth Differentiation Factor 15 as a potential disease biomarker in juvenile dermatomyositis.

OBJECTIVE: We aimed to investigate the potential of Growth Differentiation Factor 15 (GDF-15) as a novel biomarker for disease activity in Juvenile Dermatomyositis (JDM). METHODS: We recruited children with juvenile myositis including juvenile dermatomyositis (n = 77), polymyositis (n = 6), and healthy controls (n = 22). GDF-15 levels in plasma were measured using ELISA. Statistical analyses were performed using non-parametric tests. RESULTS: Levels of GDF-15 were significantly elevated in JDM compared with healthy controls (p< 0.001). GDF-15 levels exhibited strong positive correlations with disease activity scores, including the Disease Activity Score (DAS) total score, DAS skin score, DAS muscle score, and Childhood Myositis Assessment Scale (CMAS). Additionally, GDF-15 levels could differentiate between active disease and remission based on the Physician Global Assessment of muscle score. Positive correlations were observed between levels of GDF-15 and creatine kinase, neopterin, and nailfold end row loops, indicating the potential involvement of GDF-15 in muscle damage, immune activation, and vascular pathology. ROC curve analysis showed GDF-15 to be more effective in assessing disease activity in JDM than creatine kinase (AUC 0.77, p= 0.001 and AUC 0.6369, p= 0.0738, respectively). CONCLUSION: GDF-15 may serve as a valuable biomarker for assessing disease activity in JDM. It exhibits better sensitivity and specificity than creatine kinase, and the levels correlate with various disease activity scores and functional measures. GDF-15 may provide valuable information for treatment decision-making and monitoring disease progression in JDM.

Increased Otoferlin Expression in B Cells Is Associated with Muscle Weakness in Untreated Juvenile Dermatomyositis: A Pilot Study.

Otoferlin mRNA expression is increased in JDM patients' PBMCs and muscle compared to healthy controls. This study aims to evaluate the role of otoferlin in JDM disease pathophysiology and its association with disease activity in untreated children with JDM. A total of 26 untreated JDM (88.5% female, 92.3% white, non-Hispanic) and 15 healthy controls were included in this study. Otoferlin mRNA expression was determined by qRT-PCR before and a few months after therapy. Detailed flow cytometry of various cell surface markers and cytoplasmic otoferlin was performed to identify cells expressing otoferlin. In addition, muscle otoferlin expression was evaluated in situ in six untreated JDM patients and three healthy controls. There was a significant increase in otoferlin expression in JDM children compared to controls (Median 67.5 vs. 2.1; p = 0.001). There was a positive correlation between mRNA otoferlin expression and the following disease activity markers: disease activity scores (DAS)-total (rs = 0.62, p < 0.001); childhood myositis assessment scale (CMAS) (rs = -0.61, p = 0.002); neopterin (rs = 0.57, p = 0.004) and von Willebrand factor antigen (vWF: Ag) (rs = 0.60, p = 0.004). Most of the otoferlin-positive cells were unswitched B cells (63-99.4%), with 65-75% of them expressing plasmablast markers (CD19+, IgM+, CD38hi, CD24-). The findings of this pilot study suggest that otoferlin expression is associated with muscle weakness, making it a possible biomarker of disease activity. Additionally, B cells and plasmablasts were the primary cells expressing otoferlin.

Skin disease is more recalcitrant than muscle disease: A long-term prospective study of 184 children with juvenile dermatomyositis.

BACKGROUND: Persistent skin manifestations, especially calcinoses, contribute to morbidity in children with juvenile dermatomyositis. OBJECTIVE: To compare the course of skin and muscle involvement and document frequency of calcinosis in juvenile dermatomyositis. METHODS: Prospective cohort study of 184 untreated children with juvenile dermatomyositis (July 1971 to May 2019) at a single children's hospital. RESULTS: Disease Activity Scores (DASs) were persistently higher for skin versus muscle at all points; clinical inactivity (DAS ≤2) occurred earlier for muscle than skin. Among vascular features for DAS for skin, eyelid margin capillary dilatation was most frequent (54.3%) and persisted longest. Intravenous methylprednisolone reduced DAS for skin more than oral prednisone at 12 months (P = .04). Overall, 16.8% of patients (n = 31) had calcifications, with 4.9% at enrollment. Despite therapy, 25.0% of calcifications recurred and 22.6% failed to resolve; of the latter, 71.4% (n = 5) were present at enrollment. Children with persistent calcifications had longer duration of untreated disease than those whose calcifications resolved (mean 12.5 months) (P < .001). Hydroxychloroquine did not improve DAS for skin (P = .89). LIMITATIONS: DAS does not quantify nailfold capillary dropout. CONCLUSIONS: In juvenile dermatomyositis, skin disease presents with greater activity and is more recalcitrant to therapies than muscle disease. Early and aggressive treatment can limit the severity and persistence of calcifications identified later in the disease course.

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 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.

Environmental factors associated with disease flare in juvenile and adult dermatomyositis.

Objective: The aim was to assess environmental factors associated with disease flare in juvenile and adult dermatomyositis (DM). Methods: An online survey of DM patients from the USA and Canada examined smoking, sun exposure, infections, medications, vaccines, stressful life events and physical activity during the 6 months before flares, or in the past 6 months in patients without flares. Differences were evaluated by χ 2 and Fisher's exact tests, and significant univariable results were examined in multivariable logistic regression. Residential locations before flare were correlated with the National Weather Service UV index. Results: Of 210 participants (164 juvenile and 46 adult DM), 134 (63.8%) experienced a disease flare within 2 years of the survey. Subjects more often reported disease flare after sun exposure [odds ratio (OR) = 2.0, P = 0.03], although use of photoprotective measures did not differ between those with and without flare. Urinary tract infections (OR = 16.4, P = 0.005) and gastroenteritis (OR = 3.2, P = 0.04) were more frequent in the preceding 6 months in those who flared. Subjects who flared recently used NSAIDS (OR = 3.0, P = 0.0003), blood pressure medicines (OR = 3.5, P = 0.049) or medication for depression or mood changes (OR = 12.9, P = 0.015). Moving to a new house (OR = 10.3, P = 0.053) was more common in those who flared. Only sun exposure (OR = 2.2) and NSAIDs (OR = 1.9) were significant factors in multivariable analysis. Conclusion: Certain classes of environmental agents that have been associated with the initiation of DM, including sun exposure and medications, may also play a role in disease flares.

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.

Interferon-α induction and detection of anti-ro, anti-la, anti-sm, and anti-rnp autoantibodies by autoantigen microarray analysis in juvenile dermatomyositis.

OBJECTIVE: To evaluate serum interferon-α (IFNα) activity in the context of autoantibody profiles in patients with juvenile dermatomyositis (JDM). METHODS: Sera from 36 patients with JDM were analyzed. Autoantibody profiles were determined by probing microarrays, which were fabricated with ∼80 distinct autoantigens, with serum and a Cy3-conjugated secondary antibody. Arrays were scanned and analyzed to determine antigen reactivity. Serum IFNα activity was measured using a functional reporter cell assay. Sera were assayed alone or in combination with cellular material released from necrotic U937 cells to stimulate peripheral blood mononuclear cells from healthy donors in vitro, and IFNα production in culture was measured by a dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA). RESULTS: Reactivity against at least 1 of 41 autoantigens on the microarray, including Ro 52, Ro 60, La, Sm, and RNP, was observed in 75% of the serum samples from patients with JDM. IFNα activity was detected in 7 samples by reporter cell assay. The reporter cell assay showed a significant association of reactivity against Ro, La, Sm, and proliferating cell nuclear antigen with serum IFNα activity (P = 0.005). Significance Analysis of Microarrays (SAM) identified increased reactivity against Sm, RNP, Ro 52, U1-C, and Mi-2 in these sera. Sixteen samples induced IFNα production as measured by DELFIA, and there was a significant association of reactivity against Ro, La, Sm, and RNP with the induction of IFNα by serum and necrotic cell material (P = 0.034). SAM identified increased reactivity against Ro 60 in these sera. CONCLUSION: These data support the hypothesis that nucleic acid-associated autoantibodies, including the Ro/La and Sm/RNP complexes, may stimulate the production of active IFNα in children with JDM.

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.

Proof-of-concept study evaluating humoral primary immunodeficiencies via CJ:KREC ratio and serum BAFF level.

Humoral primary immunodeficiencies are the most prevalent form of primary immunodeficiency (PID). Currently, there is no convenient method to quantify newly formed B cells. The aim of this proof-of-concept study was to quantitate the ratio of coding joints (CJs) to Kappa-deleting recombination excision circles (KRECs) and serum B cell activating factor (BAFF) in patients with humoral primary immunodeficiency and assess if they correlate with disease severity. This IRB-approved study was conducted at one academic children's hospital. Patients with humoral PIDs and healthy controls were included. CJ and KREC levels were measured via qPCR. Serum BAFF levels were measured using Mesoscale. 16 patients with humoral PID and 5 healthy controls were included. The mean CJ:KREC ratio in the CVID, antibody deficiency syndromes, and controls groups, respectively were 13.04 ± 9.5, 5.25 ± 4.1, and 4.38 ± 2.5 (p = 0.059). The mean serum BAFF levels in CVID, antibody deficiency syndromes and controls were 216.3 ± 290 pg/mL, 107.9 ± 94 pg/mL and 50.9 ± 12 pg/mL, respectively (p = 0.271). When the CVID patients were subdivided into CVID with or without lymphoproliferative features, the BAFF level was substantially higher in the CVID with lymphoproliferation cohort (mean 372.4 ± 361 pg/mL, p = 0.031). Elevated CJ:KREC ratio was observed in CVID, although statistical significance was not achieved, likely due to the small sample size. Serum BAFF levels were significantly higher in CVID patients with lymphoproliferative features. We speculate that the CJ:KREC ratio and serum BAFF levels can be utilized in patients with humoral PID, once more extensive studies confirm this exploratory investigation.

Increased percentage of HLA-DR T cells in untreated juvenile dermatomyositis.

This study investigates HLA-DR expression on activated T cells and serum neopterin levels in Juvenile Dermatomyositis (JDM) children pre- and post-treatment. Sixty-nine JDM children (less than 18 years) were included. Elevated HLA-DR+ T cells (>7 %) were observed in 19 % of untreated cases. Post-treatment, mean HLA-DR+ T cells decreased from 5.1 to 2.9 (P < 0.001), and serum neopterin levels declined from 19.3 to 9.1 nmol/L (P < 0.0001). A positive correlation between serum neopterin and HLA-DR T cell percentage was observed (r = 0.39, P = 0.01). Intravenous steroid treatment exhibited a 47.4 % improvement in HLA-DR+ T cells and a 50.5 % reduction in serum neopterin levels, in contrast to 14.8 % and 34.1 % in the oral steroid group. In conclusion, treatment, particularly with IV steroids, significantly improved HLA-DR+ T cells percentage and neopterin levels. A correlation between HLA-DR+ T cells percentage and serum neopterin was noted in untreated JDM patients.

Increased expression of vascular cell adhesion molecule 1 in muscle biopsy samples from juvenile dermatomyositis patients with short duration of untreated disease is regulated by miR-126.

OBJECTIVE: To evaluate the effect of duration of untreated disease on vascular cell adhesion molecule 1 (VCAM-1) and microRNA (miRNA) expression in muscle biopsy samples from children with juvenile dermatomyositis (DM) as well as its effect on soluble VCAM-1 (sVCAM-1) and tumor necrosis factor α (TNFα) concentrations in sera from these children. METHODS: We enrolled 28 untreated children with juvenile DM and 8 pediatric controls. Eleven children with juvenile DM had short duration of untreated disease (symptoms for ≤2 months before muscle biopsy), and 17 had long duration of untreated disease (symptoms for >2 months before muscle biopsy). Vascular structures, characterized by immunofluorescence using antibodies against von Willebrand factor, VCAM-1, and α-smooth muscle actin, were measured for total area and intensity. Circulating sVCAM-1 and TNFα levels were determined in patients with short duration of untreated disease, patients with long duration of untreated disease, and controls. Differential expression of microRNA-126 (miR-126) in muscle biopsy samples from the 2 patient groups and the control group was detected by miRNA expression profiling and confirmed by quantitative reverse transcription-polymerase chain reaction in muscle biopsy samples from the 3 groups. RESULTS: Juvenile DM patients with short duration of untreated disease had significantly higher total positive area and intensity/high power field of VCAM-1 expression than did juvenile DM patients with long duration of untreated disease (P = 0.043 and P = 0.015, respectively) or controls (P = 0.004 and P = 0.001, respectively). Von Willebrand factor antigen-positive vasculature displayed greater VCAM-1 intensity in patients with short duration of untreated disease than in patients with long duration of untreated disease (P = 0.001). Circulating levels of sVCAM-1 and TNFα were significantly higher in patients with short duration of untreated disease than in controls (P = 0.013 and P = 0.048, respectively). The miRNA miR-126, a negative regulator of VCAM-1 expression, was significantly decreased (3.39-fold; P < 0.006) in patients with short duration of untreated disease compared to controls, while miR-126 expression in patients with long duration of untreated disease did not differ significantly compared to controls. CONCLUSION: In patients with short duration of untreated disease, miR-126 down-regulation is associated with increased VCAM-1 in both muscle and blood, suggesting that VCAM-1 plays a critical role early in juvenile DM disease pathophysiology, augmented by TNFα.

Methylation alterations of WT1 and homeobox genes in inflamed muscle biopsy samples from patients with untreated juvenile dermatomyositis suggest self-renewal capacity.

OBJECTIVE: To determine the effect of methylation alteration in inflamed muscles from children with juvenile dermatomyositis (DM) and other idiopathic inflammatory myopathies (IIMs). METHODS: Magnetic resonance imaging-directed diagnostic muscle biopsies yielded samples from 20 children with juvenile DM, which were used for genome-wide DNA methylation profiling, as were muscle biopsy samples from 4 healthy controls. Bisulfite treatment followed by pyrosequencing confirmed methylation status in juvenile DM and other IIMs. Immunohistochemistry defined localization and expression levels of WT1. RESULTS: Comparison of genome-wide DNA methylation profiling between juvenile DM muscle and normal control muscle revealed 27 genes with a significant methylation difference between the groups. These genes were enriched with transcription factors and/or cell cycle regulators and were unrelated to duration of untreated disease. Six homeobox genes were among them; ALX4, HOXC11, HOXD3, and HOXD4 were hypomethylated, while EMX2 and HOXB1 were hypermethylated. WT1 was significantly hypomethylated in juvenile DM (Δß = -0.41, P < 0.001). Bisulfite pyrosequencing verification in samples from 56 patients with juvenile DM confirmed the methylation alterations of these genes. Similar methylation alterations were observed in juvenile polymyositis (n = 5) and other IIMs (n = 9). Concordant with the other findings, WT1 protein was increased in juvenile DM muscle, with average positive staining of 11.6%, but was undetectable in normal muscle (P < 0.001). CONCLUSION: These results suggest that affected muscles of children with juvenile DM and IIMs have the capacity to be repaired, and that homeobox and WT1 genes are epigenetically marked to facilitate this repair process, potentially suggesting new avenues of therapeutic intervention.

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

OBJECTIVE: This study determined if an accessible, serologic indicator of vascular disease activity, the von Willebrand factor antigen (vWF:Ag), was useful to assess disease activity in children with juvenile dermatomyositis (JDM), a rare disease, but the most common of the pediatric inflammatory myopathies. METHODS: A total of 305 children, median age 10 years, 72.5% female, 76.5% white, with definite/probable JDM at diagnosis, were enrolled in the Ann & Robert H. Lurie Cure JM Juvenile Myositis Repository, a longitudinal database. Disease Activity Score (DAS) and vWF:Ag data were obtained at each visit. These data were analyzed using generalized estimating equation (GEE) models (both linear and logistic) to determine if vWF:Ag reflects disease severity in children with JDM. A secondary analysis was performed for untreated active JDM to exclude the effect of medications on vWF:Ag. RESULT: The vWF:Ag test was elevated in 25% of untreated JDM. We found that patients with elevated vWF:Ag had a 2.55-fold higher DAS total (CI95: 1.83-3.27, p < 0.001). Patients with difficulty swallowing had 2.57 higher odds of elevated vWF:Ag (CI95: 1.5-4.38, p < 0.001); those with more generalized skin involvement had 2.58-fold higher odds of elevated vWF:Ag (CI95: 1.27-5.23, p = 0.006); and those with eyelid peripheral blood vessel dilation had 1.32-fold higher odds of elevated vWF:Ag (CI95: 1.01-1.72, p = 0.036). Untreated JDM with elevated vWF:Ag had more muscle weakness and higher muscle enzymes, neopterin and erythrocyte sedimentation rate compared to JDM patients with a normal vWF:Ag. CONCLUSION: vWF:Ag elevation is a widely accessible concomitant of active disease in 25% of JDM.

Juvenile Dermatomyositis: Association between Nail Fold Capillary End Row Loops Area Under the Curve and Disease Damage Indicators.

Background: Juvenile Dermatomyositis (JDM) is a rare autoimmune disease characterized by skin and muscle inflammation. The loss of nail fold capillary end row loops (ERL) is evidence of small vessel involvement in JDM. This study aimed to examine the association of ERL over the disease course and evidence of disease damage. Methods: We analyzed data from 68 initially treatment-naïve JDM children who had been observed for at least five years with multiple ERL density assessments. The JDM disease courses were categorized into monocyclic short, monocyclic long, polycyclic, and chronic. The ERL capillary count was cumulatively evaluated using the area under the curve (AUC) method. Results: The mean ERL density for the treatment-naive JDM was significantly lower than that of their healthy controls (4.8±1.6 /mm vs. 7.9±0.9 /mm; p <0.0001). The ERL AUC was significantly lower in children with chronic disease course compared to those with monocyclic short (p =0.001) or monocyclic long disease course (p =0.013). JDM patients with lipodystrophy had lower ERL AUC than those without lipodystrophy (p =0.04). There was no association between ERL AUC and calcifications or fractures. Conclusion: Persistently decreased ERL capillary density, evident by low ERL AUC, is associated with chronic disease course and lipodystrophy in JDM. Despite medical therapy, the mean ERL count remained below normal even after five years, particularly in polycyclic and chronic cases. Therefore, the goal of restoring normal capillary density in children with JDM might be challenging and require novel therapeutic strategies targeting their underlying endothelial dysfunction.