Clinical Features and Immunogenetic Risk Factors Associated With Additional Autoantibodies in Anti-Transcriptional Intermediary Factor 1γ Juvenile-Onset Dermatomyositis

OBJECTIVE

Novel autoantibody specificities including anti-CCAR1 were recently discovered in adult patients with anti-transcriptional intermediary factor (TIF1)-positive dermatomyositis (DM) and were associated with attenuated cancer emergence. The aims of the present study were to examine whether these autoantibodies occur in patients with juvenile-onset DM (JDM) and to determine their associated features.

METHODS

Sera from 150 patients with anti-TIF1γ autoantibody-positive JDM in a cross-sectional cohort and 90 juvenile healthy controls were assayed for anti-CCAR1, anti-C1Z1, anti-IMMT, anti-TBL1XR1, and anti-Sp4 autoantibodies. Demographics, myositis autoantibodies, clinical features, medications, outcomes, and HLA-DRB1 and HLA-DQA1 alleles were compared between those with and without these autoantibodies.

RESULTS

Any one of the anti-TIF1γ-associated autoantibodies was present in 44 patients (29%) overall, including 25 (17%) with anti-Sp4, 22 (15%) with anti-TBL1XR1, 14 (9%) with anti-CCAR1, 2 (1%) with anti-C1Z1, and 2 (1%) with anti-IMMT autoantibodies. These anti-TIF1γ-associated autoantibodies frequently co-occurred. Patients with any of the anti-TIF1γ-associated autoantibodies had less frequent falling (34% [15] vs. 53% [56], P = 0.032) and lower peak muscle enzymes. None of the patients had cancer. Among White patients, HLA-DRB1*03 was protective against an anti-TIF1γ-associated autoantibody (odds ratio 0.20, 95% confidence interval 0.07-0.52).

CONCLUSION

Autoantibodies associated with anti-TIF1γ were found in isolation and in combination among a subset of patients with JDM. Patients with these autoantibodies had less severe muscle disease and were not enriched for HLA-DRB1*03. Additional autoantibodies among patients with positive anti-TIF1γ with JDM likely contribute to the heterogeneity of the anti-TIF1γ serologic subgroup.

Performance of the 2017 EULAR/ACR Classification Criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups: a scoping review

The 2017 EULAR/ACR classification criteria for adult/juvenile idiopathic inflammatory myopathies (IIM) were established using a data-driven approach by an international group of myositis experts to allow classification of IIM and its major subtypes. Since their publication, the performance of the criteria has been tested in multiple cohorts worldwide and significant limitations have been identified. Moreover, the understanding and classification of IIM have evolved since 2017. This scoping review was undertaken as part of a large international project to revise the EULAR/ACR criteria and aims to i) summarise the evidence from the current literature on the performance characteristics of the 2017 EULAR/ACR classification criteria in various cohorts and IIM subtypes, and ii) delineate the factors that need to be considered in the revision of the classification criteria. A systematic search of Medline (via PubMed), Cumulative Index to Nursing and Allied Health Literature, and conference abstract archives was conducted independently by three investigators for studies on the EULAR/ACR criteria published between October 2017 and January 2023. This scoping review of 19 articles and 13 abstracts revealed overall good performance characteristics of the EULAR/ACR criteria for IIM, yet deficiencies in lack of inclusion of certain IIM subtypes, such as immune mediated necrotising myopathy, amyopathic dermatomyositis, antisynthetase syndrome and overlap myositis. Published modifications that may improve the performance characteristics of the criteria for classification of IIM subtypes were also summarised. The results of this review suggest that a revision of the EULAR/ACR criteria is warranted.

Myositis-Associated Autoantibodies in Patients With Juvenile Myositis Are Associated With Refractory Disease and Mortality

OBJECTIVE

Myositis-associated autoantibodies (MAAs) have been associated with overlap myositis, certain disease manifestations such as interstitial lung disease (ILD), and worse prognosis in the idiopathic inflammatory myopathies. MAAs overall remain largely uncharacterized in patients with juvenile-onset myositis. Moreover, it is unknown whether the number of MAAs is associated with disease severity.

METHODS

Patients with juvenile myositis in cross-sectional natural history studies who underwent testing for myositis autoantibodies were included. Demographics, myositis autoantibodies, clinical characteristics, medications received, and outcomes of those with and without MAAs were compared. Multivariable logistic regression was performed to determine whether the number of MAAs detected was associated with severe disease features.

RESULTS

Among 551 patients, 36% had an MAA and 13% had more than one MAA. Among those who were MAA positive, there was a higher frequency of overlap myositis (18% vs 5.9%, P < 0.001). MAA positivity was associated with certain clinical features, including Raynaud phenomenon (odds ratio [OR] 2.44, 95% confidence interval [CI] 1.41-4.28) and ILD (OR 3.43, 95% CI 1.75-6.96), as well as a chronic disease course (OR 1.72, 95% CI 1.10-2.72) and mortality (OR 3.76, 95% CI 1.72-8.43). The number of MAAs was also associated with mortality (OR 1.83, 95% CI 1.16-2.86).

CONCLUSION

MAAs were prevalent in a large cohort of patients with juvenile myositis. ILD, refractory disease, and mortality were associated with MAA positivity. Prospective studies are needed to determine whether early detection of MAAs may lead to improved outcomes for patients with juvenile myositis.

Development of a computed tomography calcium scoring technique for assessing calcinosis distribution, pattern and burden in dermatomyositis

OBJECTIVES

To utilize whole-body CT imaging and calcium scoring techniques as tools for calcinosis assessment in a prospective cohort of patients with adult and juvenile dermatomyositis (DM and JDM, respectively).

METHODS

Thirty-one patients (14 DM and 17 JDM) who fulfilled Bohan and Peter Classification criteria as probable or definite DM, the EULAR-ACR criteria for definite DM, and with calcinosis identified by physical examination or prior imaging studies were included. Non-contrast whole-body CT scans were obtained using low-dose radiation procedures. Scans were read qualitatively and quantitated. We calculated the sensitivity and specificity of calcinosis detection of physician physical exam against CT. We quantified calcinosis burden using the Agatston scoring technique.

RESULTS

We identified five distinct calcinosis patterns: Clustered, Disjoint, Interfascial, Confluent and Fluid-filled. Novel locations of calcinosis were observed, including the cardiac tissue, pelvic and shoulder bursa, and the spermatic cord. Quantitative measures using Agatston scoring for calcinosis were used in regional distributions across the body. Physician physical exams had a sensitivity of 59% and a specificity of 90% compared with CT detection. A higher calcium score correlated with higher Physician Global Damage, Calcinosis Severity scores, and disease duration.

CONCLUSION

Whole-body CT scans and the Agatston scoring metric define distinct calcinosis patterns and provide novel insights relating to calcinosis in DM and JDM patients. Physicians' physical examinations underrepresented the presence of calcium. Calcium scoring of CT scans correlated with clinical measures, which suggests that this method may be used to assess calcinosis and follow its progression.

Performance of the 2016 ACR-EULAR Myositis Response Criteria in adult dermatomyositis/polymyositis therapeutic trials and consensus profiles

OBJECTIVE

The ACR-EULAR Myositis Response Criteria (MRC) were developed as a composite measure using absolute percentage change in six core set measures (CSMs). We aimed to further validate the MRC by assessing the contribution of each CSM, frequency of strength vs extramuscular activity improvement, representation of patient-reported outcome measures (PROM), and frequency of CSM worsening.

METHODS

Data from adult dermatomyositis/polymyositis patients in the rituximab (n = 147), etanercept (n = 14), and abatacept (n = 19) trials, and consensus patient profiles (n = 232) were evaluated. The Total Improvement Score (TIS), number of improving vs worsening CSMs, frequency of improvement with and without muscle-related CSMs, and contribution of PROM were evaluated by MRC category. Regression analysis was performed to assess contribution of each CSM to the MRC.

RESULTS

Of 412 adults with dermatomyositis/polymyositis, there were 37%, 24%, 25%, and 14% with no, minimal, moderate, and major MRC improvement, respectively. The number of improving CSMs and absolute percentage change in all CSMs increased by improvement category. In minimal-moderate improvement, only physician-reported disease activity contributed significantly more than expected by MRC. Of patients with at least minimal improvement, 95% had improvement in muscle-related measures and a majority (84%) had improvement in PROM. Patients with minimal improvement had worsening in a median of 1 CSM, and most patients with moderate-major improvement had no worsening CSMs. Physician assessment of change generally agreed with MRC improvement categories.

CONCLUSION

The ACR-EULAR MRC performs consistently across multiple studies, further supporting its use as an efficacy end point in future myositis therapeutic trials.

Performance of the 2016 ACR-EULAR myositis response criteria in juvenile dermatomyositis therapeutic trials and consensus profiles

OBJECTIVES

The 2016 ACR-EULAR Response Criteria for JDM was developed as a composite measure with differential weights of six core set measures (CSMs) to calculate a Total Improvement Score (TIS). We assessed the contribution of each CSM, representation of muscle-related and patient-reported CSMs towards improvement, and frequency of CSM worsening across myositis response criteria (MRC) categories in validation of MRC.

METHODS

Data from JDM patients in the Rituximab in Myositis trial (n = 48), PRINTO JDM trial (n = 139), and consensus patient profiles (n = 273) were included. Observed vs expected CSM contributions were compared using Sign test. Characteristics of MRC categories were compared by Wilcoxon tests with Bonferroni adjustment. Spearman correlation of changes in TIS and individual CSMs were examined. Agreement between physician-assessed change and MRC categories was evaluated by weighted Cohen's kappa.

RESULTS

Of 457 JDM patients with IMACS CSMs and 380 with PRINTO CSMs, 9-13% had minimal, 19-23% had moderate and 41-50% had major improvement. The number of improved and absolute percentage change of CSMs increased by MRC improvement level. Patients with minimal improvement by MRC had a median of 0-1 CSM worsened, and those with moderate/major improvement had a median of zero worsening CSMs. Of patients improved by MRC, 94-95% had improvement in muscle strength and 93-95% had improvement in ≥1 patient-reported CSM. IMACS and PRINTO CSMs performed similarly. Physician-rated change and MRC improvement categories had moderate-to-substantial agreement (Kappa 0.5-0.7).

CONCLUSION

The ACR-EULAR MRC perform consistently across multiple studies, supporting its further use as an efficacy end point in JDM trials.

Association of anti-TPM4 autoantibodies with vasculopathic cutaneous manifestations in juvenile dermatomyositis

OBJECTIVES

AECAs are detected in multiple forms of vasculitis or vasculopathy, including JDM. High levels of tropomyosin alpha-4 chain (TPM4) gene expression in cutaneous lesions and TPM4 protein expression in some endothelial cells (ECs) have been proven. Furthermore, the presence of autoantibodies to tropomyosin proteins have been discovered in DM. We therefore investigated whether anti-TPM4 autoantibodies are an AECA in JDM and are correlated with clinical features of JDM.

METHODS

The expression of TPM4 protein in cultured normal human dermal microvascular ECs was investigated by Western blotting. Plasma samples from 63 children with JDM, 50 children with polyarticular JIA (pJIA) and 40 healthy children (HC) were tested for the presence of anti-TPM4 autoantibodies using an ELISA. Clinical features were compared between JDM patients with and without anti-TPM4 autoantibodies.

RESULTS

Autoantibodies to TPM4 were detected in the plasma of 30% of JDM, 2% of pJIA (P < 0.0001) and 0% of HC (P < 0.0001). In JDM, anti-TPM4 autoantibodies were associated with the presence of cutaneous ulcers (53%; P = 0.02), shawl sign rash (47%; P = 0.03), mucous membrane lesions (84%; P = 0.04) and subcutaneous edema (42%; P < 0.05). Anti-TPM4 autoantibodies significantly correlated with the use of intravenous steroids and IVIG therapy in JDM (both P = 0.01). The total number of medications received was higher in patients with anti-TPM4 autoantibodies (P = 0.02).

CONCLUSION

Anti-TPM4 autoantibodies are detected frequently in children with JDM and are novel myositis-associated autoantibodies. Their presence correlates with vasculopathic and other cutaneous manifestations of JDM that may be indicative of more refractory disease.

Shared and Distinctive Transcriptomic and Proteomic Pathways in Adult and Juvenile Dermatomyositis

OBJECTIVE

Transcript and protein expression were interrogated to examine gene locus and pathway regulation in the peripheral blood of active adult dermatomyositis (DM) and juvenile DM patients receiving immunosuppressive therapies.

METHODS

Expression data from 14 DM and 12 juvenile DM patients were compared to matched healthy controls. Regulatory effects at the transcript and protein level were analyzed by multi-enrichment analysis for assessment of affected pathways within DM and juvenile DM.

RESULTS

Expression of 1,124 gene loci were significantly altered at the transcript or protein levels across DM or juvenile DM, with 70 genes shared. A subset of interferon-stimulated genes was elevated, including CXCL10, ISG15, OAS1, CLEC4A, and STAT1. Innate immune markers specific to neutrophil granules and neutrophil extracellular traps were up-regulated in both DM and juvenile DM, including BPI, CTSG, ELANE, LTF, MPO, and MMP8. Pathway analysis revealed up-regulation of PI3K/AKT, ERK, and p38 MAPK signaling, whose central components were broadly up-regulated in DM, while peripheral upstream and downstream components were differentially regulated in both DM and juvenile DM. Up-regulated components shared by DM and juvenile DM included cytokine:receptor pairs LGALS9:HAVCR2, LTF/NAMPT/S100A8/HSPA1A:TLR4, CSF2:CSF2RA, EPO:EPOR, FGF2/FGF8:FGFR, several Bcl-2 components, and numerous glycolytic enzymes. Pathways unique to DM included sirtuin signaling, aryl hydrocarbon receptor signaling, protein ubiquitination, and granzyme B signaling.

CONCLUSION

The combination of proteomics and transcript expression by multi-enrichment analysis broadened the identification of up- and down-regulated pathways among active DM and juvenile DM patients. These pathways, particularly those which feed into PI3K/AKT and MAPK signaling and neutrophil degranulation, may be potential therapeutic targets.

Therapeutic Development in Polyarticular Course Juvenile Idiopathic Arthritis: Extrapolation, Dose Selection, and Clinical Trial Design

OBJECTIVE

Stakeholders met to address persistent challenges facing the development of therapeutics for polyarticular juvenile idiopathic arthritis (pJIA), which result in fewer approved therapies for children with pJIA than adults with rheumatoid arthritis (RA) and long lag times from adult RA approval to pediatric labeling. Ensuring that new medications are authorized in a timely manner to meet the needs of JIA patients worldwide is critically important to multiple stakeholders.

METHODS

The Food and Drug Administration in collaboration with the University of Maryland Center for Regulatory Science and Innovation held a public workshop entitled "Accelerating Drug Development for pJIA" on October 2, 2019, to address challenges surrounding access to new medications for children and adolescents with pJIA. Regulatory, academic, and industry stakeholders, as well as patient representatives, participated in the workshop, which consisted of 4 sessions, including panel discussions.

RESULTS

The workshop facilitated broad public discussion of challenges facing the development of pJIA therapeutics, highlighting areas of need and outlining opportunities to expedite development, while underscoring the necessity of close collaboration between all stakeholders, including patients and families.

CONCLUSION

This report summarizes key aspects of the workshop, including the appropriate application of innovative approaches to the development of pJIA therapeutics, including extrapolation, to address current challenges and provide timely access to newer safe and effective treatments. Long-term safety assessment is of pressing concern to stakeholders and cannot be fully extrapolated from adult studies but requires consistent postmarketing long-term follow-up.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Urine proteomics by mass spectrometry identifies proteins involved in key pathogenic pathways in patients with juvenile dermatomyositis

OBJECTIVES

To identify and validate biomarkers in JDM patients using a multiplexing tandem mass tag urine proteome profiling approach.

METHODS

First morning void urine samples were collected from JDM patients (n = 20) and healthy control subjects (n = 21) and processed for analysis using a standardized liquid chromatography-tandem mass spectrometry approach. Biomarkers with significantly altered levels were correlated with clinical measures of myositis disease activity and damage. A subset of candidate biomarkers was validated using commercially available ELISA kits.

RESULTS

In total, 2348 proteins were detected in the samples, with 275 proteins quantified across all samples. Among the differentially altered proteins, cathepsin D and galectin-3 binding protein were significantly increased in the urine of JDM patients (adjusted P < 0.05), supporting previous findings in myositis patients. These two candidate biomarkers were confirmed with ELISAs. Cathepsin D positively correlated with Myositis Damage Index (r = 0.57, P < 0.05) and negatively correlated with the Childhood Myositis Assessment Scale (r = -0.54, P < 0.05). We also identified novel JDM candidate biomarkers involved with key features of myositis, including extracellular matrix remodelling proteins.

CONCLUSION

This study confirmed the presence of several proteins in the urine of JDM patients that were previously found to be elevated in the blood of myositis patients and identified novel candidate biomarkers that require validation. These results support the use of urine as a source for biomarker development in JDM.

Identification of Novel Associations and Localization of Signals in Idiopathic Inflammatory Myopathies Using Genome-Wide Imputation

OBJECTIVE

The idiopathic inflammatory myopathies (IIMs) are heterogeneous diseases thought to be initiated by immune activation in genetically predisposed individuals. We imputed variants from the ImmunoChip array using a large reference panel to fine-map associations and identify novel associations in IIM.

METHODS

We analyzed 2,565 Caucasian IIM patient samples collected through the Myositis Genetics Consortium (MYOGEN) and 10,260 ethnically matched control samples. We imputed 1,648,116 variants from the ImmunoChip array using the Haplotype Reference Consortium panel and conducted association analysis on IIM and clinical and serologic subgroups.

RESULTS

The HLA locus was consistently the most significantly associated region. Four non-HLA regions reached genome-wide significance, SDK2 and LINC00924 (both novel) and STAT4 in the whole IIM cohort, with evidence of independent variants in STAT4, and NAB1 in the polymyositis (PM) subgroup. We also found suggestive evidence of association with loci previously associated with other autoimmune rheumatic diseases (TEC and LTBR). We identified more significant associations than those previously reported in IIM for STAT4 and DGKQ in the total cohort, for NAB1 and FAM167A-BLK loci in PM, and for CCR5 in inclusion body myositis. We found enrichment of variants among DNase I hypersensitivity sites and histone marks associated with active transcription within blood cells.

CONCLUSION

We found novel and strong associations in IIM and PM and localized signals to single genes and immune cell types.

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.

Improvement in Disease Activity in Refractory Juvenile Dermatomyositis Following Abatacept Therapy

OBJECTIVE

An open-label 24-week study was conducted to evaluate the safety and efficacy of abatacept in patients with refractory juvenile dermatomyositis (JDM).

METHODS

Ten patients >7 years of age with moderate disease activity were enrolled in a 24-week study to examine the safety and treatment response of subcutaneous abatacept. The primary endpoint was the International Myositis Assessment and Clinical Studies Group (IMACS) Definition of Improvement (DOI). Secondary endpoints included safety, change in core set activity measures (CSMs) of IMACS and Pediatric Rheumatology International Trials Organization (PRINTO), and the ACR-EULAR response criteria for JDM. Blinded radiologists assessed thigh magnetic resonance imaging (MRI). Interferon gene score (IFNGS) was performed on whole-blood RNA by NanoString and cytokines were assessed by Luminex.

RESULTS

Five patients achieved DOI at week 12, and nine achieved DOI at week 24, including two with minimal, four moderate, and three with major improvement by ACR-EULAR response criteria using IMACS CSMs. All CSMs improved from baseline at weeks 12 and 24, except muscle enzymes. Daily corticosteroid dose decreased from a mean of 16.7 mg at baseline to 10.2 mg at week 24 (p=0.002). Average MRI muscle edema score decreased from baseline 5.3 to 2.3 at week 24 (p=0.01). Six patients had down-trending IFNGS and galectin-9 at week 24. Decreases in IFNGS, IP-10, galectin-9 and IL-2 correlated with improvement in disease activity and in MRI muscle edema. Eleven Grade 2 or 3 treatment-emergent adverse events were observed.

CONCLUSIONS

This open-label study demonstrated abatacept may be beneficial for treatment-refractory JDM.

A novel estrogen receptor 1-sphingomyelin phosphodiesterase acid like 3B pathway mediates rituximab response in myositis patients

OBJECTIVES

The B cell depleting biologic, rituximab, is used to treat refractory autoimmune myositis. However, the beneficial effects of rituximab appear to outweigh the known contribution of B-cells in myositis. We aimed to elucidate how myositis patients respond differently to rituximab and possible alternative mechanisms of action.

METHODS

Here we have: a) comprehensively investigated concurrent mRNA and microRNA expression in muscle biopsies taken at baseline and 16 weeks post treatment in ten patients who were part of the rituximab in myositis (RIM) trial; and b) investigated the beneficial effect of rituximab on myositis muscle cells.

RESULTS

Our analyses identified an increased number of changes in gene expression in biopsies from patients who had a clinical response to rituximab (n = 5) compared with non-responders (n = 5). The two groups had completely different changes in microRNA and mRNA expression following rituximab therapy, with the exception of one mRNA, BHMT2. Networks of mRNA and microRNA with opposite direction of expression changes highlighted ESR1 as upregulated in responders. We confirmed ESR1 upregulation upon rituximab treatment of immortalized myotubes and primary human dermatomyositis muscle cells in vitro, demonstrating a direct effect of rituximab on muscle cells. Notably, despite showing a response to rituximab, human dermatomyositis primary muscle cells did not express the rituximab target, CD20. However, these cells expressed a possible alternative target of rituximab, sphingomyelinase-like phosphodiesterase 3 b (SMPDL3B).

CONCLUSION

In addition to B cell depletion, rituximab may be beneficial in myositis due to increased ESR1 signalling mediated by rituximab binding to SMPDL3B on skeletal muscle cells.

Anti-FHL1 autoantibodies in juvenile myositis are associated with anti-Ro52 autoantibodies but not with severe disease features

OBJECTIVES

Four-and-a-half LIM domains 1 (FHL1) is a muscle-specific protein. Autoantibodies against FHL1 were recently discovered in adults with idiopathic inflammatory myopathies (IIMs) and were found to be associated with clinical features and outcomes indicative of increased disease severity. Anti-FHL1 autoantibodies have not been described in children. Here, the prevalence and clinical features associated with anti-FHL1 autoantibodies were examined in a large North American cohort of juvenile patients with IIM.

METHODS

Sera from 338 juvenile IIM patients and 91 juvenile healthy controls were screened for anti-FHL1 autoantibodies by ELISA. Clinical characteristics and HLA alleles of those with and without anti-FHL1 autoantibodies were compared among those with juvenile IIM.

RESULTS

Anti-FHL1 autoantibodies were present in 10.9% of juvenile IIM patients and 1.1% of controls. The frequency of anti-FHL1 autoantibodies among clinical and serologic subgroups did not differ. A higher percentage of Asian patients had anti-FHL1 autoantibodies (11% vs 0.7%; P = 0.002). Myositis-associated autoantibodies (MAAs) [odds ratio (OR) 2.09 (CI 1.03, 4.32)], anti-Ro52 autoantibodies specifically [OR 4.17 (CI 1.83, 9.37)] and V-sign rash [OR 2.59 (CI 1.22, 5.40)] were associated with anti-FHL1 autoantibodies. There were no differences in other features or markers of disease severity. No HLA associations with anti-FHL1 autoantibodies in Caucasian myositis patients were identified.

CONCLUSION

Anti-FHL1 autoantibodies are present in ∼11% of juvenile IIM patients and commonly co-occur with MAAs, including anti-Ro52 autoantibodies. In contrast to adult IIM, anti-FHL1 autoantibodies in juvenile myositis are associated with V-sign rash but not with other distinctive clinical features or worse outcomes.

Association of anti-HSC70 autoantibodies with cutaneous ulceration and severe disease in juvenile dermatomyositis

OBJECTIVES

JDM is an inflammatory myopathy characterized by prominent vasculopathy. AECAs are frequently detected in inflammatory and autoimmune diseases. We sought to determine whether AECAs correlate with clinical features of JDM, and thus serve as biomarkers to guide therapy or predict outcome.

METHODS

Plasma samples from 63 patients with JDM, 49 patients with polyarticular JIA and 40 juvenile healthy controls were used to detect anti-heat shock cognate 71 kDa protein (HSC70) autoantibodies, a newly identified AECA, in ELISA assays. Clinical features were compared between JDM patients with and without anti-HSC70 autoantibodies.

RESULTS

Anti-HSC70 autoantibodies were detected in 35% of patients with JDM, in 0% of patients with JIA (P < 0.0001) and in 0% of healthy donors (P < 0.0001). Both the presence of cutaneous ulcers (59% vs 17%, P < 0.002) and the use of wheelchairs and/or assistive devices (64% vs 27%, P < 0.007) were strongly associated with anti-HSC70 autoantibodies in JDM. High scores on the severity of myositis damage measures at the time of measurement of anti-HSC70 autoantibodies and an increased number of hospitalizations were also associated with anti-HSC70 autoantibodies. Intravenous immunoglobulin therapy was used more often in anti-HSC70 autoantibody-positive patients.

CONCLUSION

Anti-HCS70 autoantibodies are detected frequently in children with JDM and are novel myositis-associated autoantibodies correlating with disease severity.

Phage display of environmental protein toxins and virulence factors reveals the prevalence, persistence, and genetics of antibody responses

Microbial exposures are crucial environmental factors that impact healthspan by sculpting the immune system and microbiota. Antibody profiling via Phage ImmunoPrecipitation Sequencing (PhIP-Seq) provides a high-throughput, cost-effective approach for detecting exposure and response to microbial protein products. We designed and constructed a library of 95,601 56-amino acid peptide tiles spanning 14,430 proteins with "toxin" or "virulence factor" keyword annotations. We used PhIP-Seq to profile the antibodies of ∼1,000 individuals against this "ToxScan" library. In addition to enumerating immunodominant antibody epitopes, we studied the age-dependent stability of the ToxScan profile and used a genome-wide association study to find that the MHC-II locus modulates bacterial epitope selection. We detected previously described anti-flagellin antibody responses in a Crohn's disease cohort and identified an association between anti-flagellin antibodies and juvenile dermatomyositis. PhIP-Seq with the ToxScan library is thus an effective tool for studying the environmental determinants of health and disease at cohort scale.

Baseline Factors Associated with Self-reported Disease Flares Following COVID-19 Vaccination among Adults with Systemic Rheumatic Disease: Results from the COVID-19 Global Rheumatology Alliance Vaccine Survey

OBJECTIVE

To examine the frequency of, and risk factors for, disease flare following COVID-19 vaccination in patients with systemic rheumatic disease (SRD).

METHODS

An international study was conducted from April 2 to August 16, 2021, using an online survey of 5619 adults with SRD for adverse events following COVID-19 vaccination, including flares of disease requiring a change in treatment. We examined risk factors identified a priori based on published associations with SRD activity and SARS-CoV-2 severity, including demographics, SRD type, comorbidities, vaccine type, cessation of immunosuppressive medications around vaccination, and history of reactions to non-COVID-19 vaccines, using multivariable logistic regression.

RESULTS

Flares requiring a change in treatment following COVID-19 vaccination were reported by 4.9% of patients. Compared with rheumatoid arthritis, certain SRD, including systemic lupus erythematosus (OR 1.51, 95%CI 1.03, 2.20), psoriatic arthritis (OR 1.95, 95%CI 1.20, 3.18), and polymyalgia rheumatica (OR 1.94, 95%CI 1.08, 2.48) were associated with higher odds of flare, while idiopathic inflammatory myopathies were associated with lower odds for flare (OR 0.54, 95%CI 0.31-0.96). The Oxford-AstraZeneca vaccine was associated with higher odds of flare relative to the Pfizer-BioNTech vaccine (OR 1.44, 95%CI 1.07, 1.95), as were a prior reaction to a non-COVID-19 vaccine (OR 2.50, 95%CI 1.76, 3.54) and female sex (OR 2.71, 95%CI 1.55, 4.72).

CONCLUSION

SRD flares requiring changes in treatment following COVID-19 vaccination were uncommon in this large international study. Several potential risk factors, as well as differences by disease type, warrant further examination in prospective cohorts.

Nodular Regenerative Hyperplasia of the liver in Juvenile Dermatomyositis

BACKGROUND

We present two cases of Nodular Regenerative Hyperplasia (NRH) associated with Juvenile Dermatomyositis (JDM).

CASE PRESENTATION

Case 1: A nine-year-old Caucasian male with refractory JDM and anti-NXP2 autoantibodies was diagnosed at age two. Over seven years, he developed arthritis, dysphagia, dysphonia, severe calcinosis, and colitis. Complications included recurrent cellulitis, infections, and hepatosplenomegaly. Multiple medications were chronically used, including prednisone, methotrexate, azathioprine, cyclophosphamide, mycophenolate mofetil, rituximab, tacrolimus, etanercept, abatacept, infliximab, and tocilizumab. Case 2: A 19-year-old Asian female with chronically active JDM and anti-MDA5 autoantibodies was diagnosed at age 15. Symptomatology included ulcerative skin lesions, Raynaud's phenomenon with digital ulcers, arthritis, interstitial lung disease with pulmonary hypertension, and calcinosis. Medications included chronic use of prednisone, methotrexate, abatacept, cyclophosphamide, mycophenolate mofetil, rituximab, tofacitinib, and sildenafil. In both patients, clinical symptomatology was not suggestive of liver disease or portal hypertension, but laboratory studies revealed elevated serum transaminases with progressive thrombocytopenia and no active liver-associated infections. The first patient's liver ultrasound showed coarse hepatic texture with mild echogenicity, splenomegaly, and portal hypertension. The second patient's liver ultrasound was normal, but elastography indicated increased stiffness. Liver biopsy confirmed NRH in both patients.

CONCLUSIONS

It is difficult to recognize NRH in JDM, as it often presents with elevated transaminases which may be mistaken for JDM muscle flare, corticosteroid-related fatty liver, or medication-related transaminitis. NRH has been associated with several medications used to treat JDM, including methotrexate, azathioprine, and cyclophosphamide, which should be discontinued if NRH develops. Providers should consider NRH in JDM patients with severe, refractory disease who have persistently elevated transaminases and persistent thrombocytopenia.

The Geospatial Distribution of Myositis and Its Phenotypes in the United States and Associations With Roadways: Findings From a National Myositis Patient Registry

Background

Little is known about the spatial distribution of idiopathic inflammatory myopathies (IIM) in the United States (U.S.), or their geospatial associations.

Methods

We studied a national myositis patient registry, with cases diagnosed in the contiguous U.S. from 1985–2011 and comprised of dermatomyositis (DM, n = 484), polymyositis (PM, n = 358), and inclusion body myositis (IBM, n = 318) patients. To assess the association of myositis prevalence with distance from roads, we employed log-Gaussian Cox process models, offset with population density.

Results

The U.S. IIM case distribution demonstrated a higher concentration in the Northest. DM, IBM, and cases with lung disease were more common in the East, whereas PM cases were more common in the Southeast. One area in the West and one area in the South had a significant excess in cases of DM relative to PM and of cases with lung disease relative to those without lung disease, respectively. IIM cases tended to cluster, with between-points interactions more intense in the Northeast and less in the South. There was a trend of a higher prevalence of IIM and its major phenotypes among people living within 50 m of a roadway relative to living beyond 200 m. Demographic characteristics, rural-urban commuting area, and female percentage were significantly associated with the prevalence of IIM and with major phenotypes.

Conclusions

Using a large U.S. database to evaluate the spatial distribution of IIM and its phenotypes, this study suggests clustering in some regions of the U.S. and a possible association of proximity to roadways.

47XXY and 47XXX in Scleroderma and Myositis

Objective

We undertook this study to examine the X chromosome complement in participants with systemic sclerosis (SSc) as well as idiopathic inflammatory myopathies.

Methods

The participants met classification criteria for the diseases. All participants underwent single‐nucleotide polymorphism typing. We examined X and Y single‐nucleotide polymorphism heterogeneity to determine the number of X chromosomes. For statistical comparisons, we used χ² analyses with calculation of 95% confidence intervals.

Results

Three of seventy men with SSc had 47,XXY (P = 0.0001 compared with control men). Among the 435 women with SSc, none had 47,XXX. Among 709 men with polymyositis or dermatomyositis (PM/DM), seven had 47,XXY (P = 0.0016), whereas among the 1783 women with PM/DM, two had 47,XXX. Of 147 men with inclusion body myositis (IBM), six had 47,XXY, and 1 of the 114 women with IBM had 47,XXX. For each of these myositis disease groups, the excess 47,XXY and/or 47,XXX was significantly higher compared with in controls as well as the known birth rate of Klinefelter syndrome or 47,XXX.

Conclusion

Klinefelter syndrome (47,XXY) is associated with SSc and idiopathic inflammatory myopathies, similar to other autoimmune diseases with type 1 interferon pathogenesis, namely, systemic lupus erythematosus and Sjögren syndrome.

Anti-Cortactin Autoantibodies Are Associated With Key Clinical Features in Adult Myositis But Are Rarely Present in Juvenile Myositis

OBJECTIVE

To define the prevalence and clinical phenotype of anti-cortactin autoantibodies in adult and juvenile myositis.

METHODS

In this longitudinal cohort study, anti-cortactin autoantibody titers were assessed by enzyme-linked immunosorbent assay in 670 adult myositis patients and 343 juvenile myositis patients as well as in 202 adult healthy controls and 90 juvenile healthy controls. The prevalence of anti-cortactin autoantibodies was compared among groups. Clinical features of patients with and those without anti-cortactin autoantibodies were also compared.

RESULTS

Anti-cortactin autoantibodies were more common in adult dermatomyositis (DM) patients (15%; P = 0.005), particularly those with coexisting anti-Mi-2 autoantibodies (24%; P = 0.03) or anti-NXP-2 autoantibodies (23%; P = 0.04). In adult myositis, anti-cortactin was associated with DM skin involvement (62% of patients with anti-cortactin versus 38% of patients without anti-cortactin; P = 0.03), dysphagia (36% versus 17%; P = 0.02) and coexisting anti-Ro 52 autoantibodies (47% versus 26%; P = 0.001) or anti-NT5c1a autoantibodies (59% versus 33%; P = 0.001). Moreover, the titers of anti-cortactin antibodies were higher in patients with interstitial lung disease (0.15 versus 0.12 arbitrary units; P = 0.03). The prevalence of anti-cortactin autoantibodies was not different in juvenile myositis patients (2%) or in any juvenile myositis subgroup compared to juvenile healthy controls (4%). Nonetheless, juvenile myositis patients with these autoantibodies had a higher prevalence of "mechanic's hands" (25% versus 7%; P = 0.03), a higher number of hospitalizations (2.9 versus 1.3; P = 0.04), and lower peak creatine kinase values (368 versus 818 IU/liter; P = 0.02) than those without anti-cortactin.

CONCLUSION

The prevalence of anti-cortactin autoantibodies is increased in adult DM patients with coexisting anti-Mi-2 or anti-NXP-2 autoantibodies. In adults, anti-cortactin autoantibodies are associated with dysphagia and interstitial lung disease.

Association with HLA-DRβ1 position 37 distinguishes juvenile Dermatomyositis from adult-onset myositis

Objectives

Juvenile dermatomyositis (JDM) is a rare, severe autoimmune disease and the most common idiopathic inflammatory myopathy (IIM) 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 age of disease onset may influence pathogenesis. Therefore, a JDM-focused genetic analysis was performed using the largest collection of JDM samples to date.

Methods

Caucasian JDM samples (n = 952) obtained via international collaboration were genotyped using the Illumina HumanCoreExome chip. Additional non-assayed HLA loci and genome-wide SNPs were imputed.

Results

HLA-DRB1*03:01 was confirmed as the classical HLA allele most strongly associated with JDM (OR 1.66; 95% 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 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 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.

Conclusions

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.

Preliminary Validation of Muscle Ultrasound in Juvenile Dermatomyositis (JDM)

OBJECTIVE

To compare muscle ultrasound (MUS) parameters in patients with juvenile dermatomyositis (JDM) and healthy controls, and examine their association with JDM disease activity measures and magnetic resonance imaging (MRI).

METHODS

MUS of the right mid-rectus femoris was performed in 21 patients with JDM meeting probable or definite Bohan and Peter criteria and 28 demographically-matched healthy control subjects. MUS parameters were quantitated by digital image processing, and correlated with JDM disease activity measures and semi-quantitative thigh MRI short tau inversion recovery (STIR) and T1 scores.

RESULTS

Rectus femoris MUS echogenicity was increased (median 47.8 vs 38.5, p= 0.002) in patients with JDM compared with controls. Rectus femoris MUS echogenicity correlated with Physician Global Activity (PGA), Manual Muscle Testing (MMT), and Childhood Myositis Assessment Scale (CMAS) (rs 0.4-0.54). Some MUS parameters correlated with functional quantitative measures of muscle strength: resting RF area on MUS strongly correlated with knee extension quantitative muscle testing (QMT) (rs 0.76), and contracted area correlated with proximal MMT, knee extension QMT, and CMAS (rs 0.71-0.80). MUS echogenicity correlated with both STIR and T1 MRI (rs 0.43), and T1 MRI correlated inversely with RF contracted area (rs -0.49) on MUS. There were differences in pre- and post-exercise vascular power and colour Doppler on MUS in patients with JDM vs controls, with the percentage change of post-exercise vascular power Doppler lower in JDM compared with controls (7.1% vs 100.0%).

CONCLUSIONS

These data suggest MUS may be a valuable imaging modality to assess JDM disease activity and damage.

Early experience of COVID-19 vaccination in adults with systemic rheumatic diseases: results from the COVID-19 Global Rheumatology Alliance Vaccine Survey

BACKGROUND

We describe the early experiences of adults with systemic rheumatic disease who received the COVID-19 vaccine.

METHODS

From 2 April to 30 April 2021, we conducted an online, international survey of adults with systemic rheumatic disease who received COVID-19 vaccination. We collected patient-reported data on clinician communication, beliefs and intent about discontinuing disease-modifying antirheumatic drugs (DMARDs) around the time of vaccination, and patient-reported adverse events after vaccination.

RESULTS

We analysed 2860 adults with systemic rheumatic diseases who received COVID-19 vaccination (mean age 55.3 years, 86.7% female, 86.3% white). Types of COVID-19 vaccines were Pfizer-BioNTech (53.2%), Oxford/AstraZeneca (22.6%), Moderna (21.3%), Janssen/Johnson & Johnson (1.7%) and others (1.2%). The most common rheumatic disease was rheumatoid arthritis (42.3%), and 81.2% of respondents were on a DMARD. The majority (81.9%) reported communicating with clinicians about vaccination. Most (66.9%) were willing to temporarily discontinue DMARDs to improve vaccine efficacy, although many (44.3%) were concerned about rheumatic disease flares. After vaccination, the most reported patient-reported adverse events were fatigue/somnolence (33.4%), headache (27.7%), muscle/joint pains (22.8%) and fever/chills (19.9%). Rheumatic disease flares that required medication changes occurred in 4.6%.

CONCLUSION

Among adults with systemic rheumatic disease who received COVID-19 vaccination, patient-reported adverse events were typical of those reported in the general population. Most patients were willing to temporarily discontinue DMARDs to improve vaccine efficacy. The relatively low frequency of rheumatic disease flare requiring medications was reassuring.

Anti-MDA5 autoantibodies associated with juvenile dermatomyositis constitute a distinct phenotype in North America

OBJECTIVE

Myositis-specific autoantibodies have defined distinct phenotypes of patients with juvenile myositis (JIIM). We assessed the frequency and clinical significance of anti-melanoma differentiation-associated gene 5 (MDA5) autoantibody-associated JIIM in a North American registry.

METHODS

Retrospective examination of the characteristics of 35 JIIM patients with anti-MDA5 autoantibodies was performed, and differences from other myositis-specific autoantibody groups were evaluated.

RESULTS

Anti-MDA5 autoantibodies were present in 35/453 (7.7%) of JIIM patients and associated with older age at diagnosis, and lower serum creatine kinase and aldolase levels. Patients with anti-MDA5 autoantibodies had more frequent weight loss, adenopathy, arthritis, interstitial lung disease (ILD), and less frequent falling compared with anti-transcriptional intermediary factor 1 (TIF1), anti-nuclear matrix protein 2 (NXP2) and myositis-specific autoantibody/myositis-associated autoantibody-negative patients. They had a different season of diagnosis and less frequent mechanic's hands and ILD compared with those with anti-synthetase autoantibodies. Anti-MDA5 patients received fewer medications compared with anti-TIF1, and corticosteroid treatment was shorter compared with anti-TIF1 and anti-nuclear matrix protein 2 autoantibody groups. The frequency of remission was higher in anti-MDA5 than anti-synthetase autoantibody-positive JIIM. In multivariable analyses, weight loss, arthritis and arthralgia were most strongly associated with anti-MDA5 autoantibody-positive JIIM.

CONCLUSION

Anti-MDA5 JIIM is a distinct subset, with frequent arthritis, weight loss, adenopathy and less severe myositis, and is also associated with ILD. Anti-MDA5 is distinguished from anti-synthetase autoantibody-positive JIIM by less frequent ILD, lower creatine kinase levels and differing seasons of diagnosis. Anti-MDA5 has comparable outcomes, but with the ability to discontinue steroids more rapidly and less frequent flares compared with anti-TIF1 autoantibodies, and more frequent remission compared with anti-synthetase JIIM patients.

Corticosteroid discontinuation, complete clinical response and remission in juvenile dermatomyositis

OBJECTIVE

A North American registry of JDM patients was examined for frequency of and factors associated with corticosteroid discontinuation, complete clinical response and remission.

METHODS

We evaluated probability of achieving final corticosteroid discontinuation, complete clinical response and remission in 307 JDM patients by Weibull time-to-event modelling; conditional probability of complete clinical response and remission using Bayesian network modelling; and significant predictors with multivariable Markov chain Monte-Carlo Weibull extension models.

RESULTS

The probability of corticosteroid discontinuation was 56%, complete clinical response 38% and remission 30% by 60 months after initial treatment in 105 patients. The probability of remission was conditional on corticosteroid discontinuation and complete clinical response. Photosensitivity, contractures and a longer time to complete clinical response were predictive of the time to final corticosteroid discontinuation. Anti-MJ (NXP2) autoantibodies and a Northwest residential geoclimatic zone were predictive of shorter time to complete clinical response, while dysphonia, contractures, an increase in medications within 24 months and a longer time to corticosteroid discontinuation were associated with longer time to complete clinical response. Anti-p155/140 (TIF1) autoantibodies, an increase in medications within 12-24 months, or longer times to corticosteroid discontinuation and complete clinical response were associated with longer time to remission.

CONCLUSION

JDM patients achieve favourable outcomes, including corticosteroid discontinuation, complete clinical response and remission, although timelines for these may be several years based on time-dependent analyses. These outcomes are inter-related and strong predictors of each other. Selected clinical features and myositis autoantibodies are additionally associated with these outcomes.

Risk factors associated with Pneumocystis jirovecii pneumonia in juvenile myositis in North America

OBJECTIVES

Pneumocystis jirovecii pneumonia (PJP) is associated with significant morbidity and mortality in adult myositis patients; however, there are few studies examining PJP in juvenile myositis [juvenile idiopathic inflammatory myopathy (JIIM)]. The purpose of this study was to determine the risk factors and clinical phenotypes associated with PJP in JIIM.

METHODS

An research electronic data capture (REDCap) questionnaire regarding myositis features, disease course, medications and PJP infection characteristics was completed by treating physicians for 13 JIIM patients who developed PJP (PJP+) from the USA and Canada. Myositis features and medications were compared with 147 JIIM patients without PJP (PJP-) from similar geographic regions who enrolled in National Institutes of Health natural history studies.

RESULTS

PJP+ patients were more often of Asian ancestry than PJP- patients [odds ratio (OR) 8.7; 95% CI 1.3, 57.9]. Anti- melanoma differentiation associated protein 5 (MDA5) autoantibodies (OR 12.5; 95% CI 3.0, 52.4), digital infarcts (OR 43.8; 95% CI 4.2, 460.2), skin ulcerations (OR 12.0; 95% CI 3.5, 41.2) and interstitial lung disease (OR 10.6; 95% CI 2.1, 53.9) were more frequent in PJP+ patients. Before PJP diagnosis, patients more frequently received pulse steroids, rituximab and more immunosuppressive therapy compared with PJP- patients. Seven PJP+ patients were admitted to the intensive care unit and four patients died due to PJP or its complications.

CONCLUSIONS

PJP is a severe infection in JIIM that can be associated with mortality. Having PJP was associated with more immunosuppressive therapy, anti-MDA5 autoantibodies, Asian race and certain clinical features, including digital infarcts, cutaneous ulcerations and interstitial lung disease. Prophylaxis for PJP should be considered in juvenile myositis patients with these features.

Anti-mitochondrial autoantibodies are associated with cardiomyopathy, dysphagia, and features of more severe disease in adult-onset myositis

We analyzed the prevalence of anti-mitochondrial autoantibodies (AMA) in adult- and juvenile-onset myositis longitudinal cohorts and investigated phenotypic differences in myositis patients with AMA. We screened sera from myositis patients including 619 adult- and 371 juvenile-onset dermatomyositis (DM, JDM), polymyositis (PM, JPM), inclusion body myositis (IBM), or amyopathic DM patients and from healthy controls, including 164 adults and 92 children, for AMA by ELISA. Clinical characteristics were compared between myositis patients with and without AMA. AMA were present in 5% of adult myositis patients (16 of 216 DM, 10 of 222 PM, 4 of 140 IBM, 1 of 19 amyopathic DM), 1% of juvenile myositis patients (3 of 302 JDM, 1 of 25 JPM), and 1% of both adult and juvenile healthy controls. In patients with adult-onset myositis, AMA were associated with persistent muscle weakness, Raynaud’s phenomenon, dysphagia, and cardiomyopathy. Adult myositis patients with AMA may have more severe or treatment refractory disease, as they more frequently received glucocorticoids and intravenous immunoglobulin. In juvenile myositis, children with AMA often had falling episodes and dysphagia, but no other clinical features or medications were significantly associated with AMA. AMA are present in 5% of adult myositis patients and associated with cardiomyopathy, dysphagia, and other signs of severe disease. The prevalence of AMA is not increased in patients with juvenile myositis compared to age-matched healthy controls. Our data suggest that the presence of AMA in adult myositis patients should prompt screening for cardiac and swallowing involvement.

Key Points • Approximately 5% of a large North American cohort of adult myositis patients have anti-mitochondrial autoantibodies. • Adults with anti-mitochondrial autoantibodies often have chronic weakness, Raynaud’s, dysphagia, cardiomyopathy, and more severe disease. • Anti-mitochondrial autoantibodies are rare in juvenile myositis and not associated with a specific clinical phenotype.

Distinct interferon signatures and cytokine patterns define additional systemic autoinflammatory diseases

BACKGROUNDUndifferentiated systemic autoinflammatory diseases (USAIDs) present diagnostic and therapeutic challenges. Chronic interferon (IFN) signaling and cytokine dysregulation may identify diseases with available targeted treatments.METHODSSixty-six consecutively referred USAID patients underwent underwent screening for the presence of an interferon signature using a standardized type-I IFN-response-gene score (IRG-S), cytokine profiling, and genetic evaluation by next-generation sequencing.RESULTSThirty-six USAID patients (55%) had elevated IRG-S. Neutrophilic panniculitis (40% vs. 0%), basal ganglia calcifications (46% vs. 0%), interstitial lung disease (47% vs. 5%), and myositis (60% vs. 10%) were more prevalent in patients with elevated IRG-S. Moderate IRG-S elevation and highly elevated serum IL-18 distinguished 8 patients with pulmonary alveolar proteinosis (PAP) and recurrent macrophage activation syndrome (MAS). Among patients with panniculitis and progressive cytopenias, 2 patients were compound heterozygous for potentially novel LRBA mutations, 4 patients harbored potentially novel splice variants in IKBKG (which encodes NF-κB essential modulator [NEMO]), and 6 patients had de novo frameshift mutations in SAMD9L. Of additional 12 patients with elevated IRG-S and CANDLE-, SAVI- or Aicardi-Goutières syndrome-like (AGS-like) phenotypes, 5 patients carried mutations in either SAMHD1, TREX1, PSMB8, or PSMG2. Two patients had anti-MDA5 autoantibody-positive juvenile dermatomyositis, and 7 could not be classified. Patients with LRBA, IKBKG, and SAMD9L mutations showed a pattern of IRG elevation that suggests prominent NF-κB activation different from the canonical interferonopathies CANDLE, SAVI, and AGS.CONCLUSIONSIn patients with elevated IRG-S, we identified characteristic clinical features and 3 additional autoinflammatory diseases: IL-18-mediated PAP and recurrent MAS (IL-18PAP-MAS), NEMO deleted exon 5-autoinflammatory syndrome (NEMO-NDAS), and SAMD9L-associated autoinflammatory disease (SAMD9L-SAAD). The IRG-S expands the diagnostic armamentarium in evaluating USAIDs and points to different pathways regulating IRG expression.TRIAL REGISTRATIONClinicalTrials.gov NCT02974595.FUNDINGThe Intramural Research Program of the NIH, NIAID, NIAMS, and the Clinical Center.

Association of Ultraviolet Radiation Exposure With Dermatomyositis in a National Myositis Patient Registry

OBJECTIVE

Dermatomyositis (DM) has been associated with geospatial differences in ultraviolet (UV) radiation, but the role of individual determinants of UV exposure prior to diagnosis is unknown. The objective was to examine the role of those individual determinants.

METHODS

We analyzed questionnaire data from 1,350 adults in a US national myositis registry (638 with DM, 422 with polymyositis [PM], and 290 with inclusion body myositis [IBM] diagnosed at ages 18-65 years), examining the likelihood of DM compared with PM and IBM diagnosis, in relation to self-reported sunburn history and job- and hobby-related sun exposures in the year prior to diagnosis. We estimated odds ratios (ORs) and 95% confidence intervals (95% CIs) using logistic regression adjusted for age, skin tone, and sex, to determine the association of individual UV exposures with DM diagnosis. We also evaluated the proportion of DM by maximum daily ambient UV exposure, based on UVB erythemal irradiances for participant residence in the year prior to diagnosis.

RESULTS

DM was associated with sunburn in the year before diagnosis (2 or more sunburns OR 1.77 [95% CI 1.28-2.43] versus PM/IBM; 1 sunburn OR 1.44 [95% CI 1.06-1.95]) and with having elevated job- or hobby-related sun exposure (high exposure OR 1.64 [95% CI 1.08-2.49] or moderate exposure OR 1.35 [95% CI 1.02-1.78] versus low or no exposure). Ambient UV intensity was associated with DM in females (β = 3.97, P = 0.046), but not overall.

CONCLUSION

Our findings suggest that high or moderate personal exposure to intense sunlight is associated with developing DM compared with other types of myositis. Prospective research on UV exposure as a modifiable risk factor for DM is warranted.

New Medications Are Needed for Children With Juvenile Idiopathic Arthritis

OBJECTIVE

To document the need for additional Food and Drug Administration (FDA)-approved medications for the treatment of juvenile idiopathic arthritis (JIA).

METHODS

The electronic medical records of JIA patients treated at Cincinnati Children's Hospital Medical Center (CCHMC) and data from JIA patients enrolled in the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry were included in this study. Unmet medication need was defined in 2 ways: (a) the presence of chronically uncontrolled JIA, defined as a physician global assessment of JIA activity ≥3 (on a 0-10 scale, where 0 = inactive) OR ≥3 joints with active arthritis OR a patient global assessment of well-being ≥3 (on a 0-10 scale, where 0 = very well), despite sequential use of ≥2 biologic disease-modifying antirheumatic drugs (bDMARDs); and (b) the use of ≥1 bDMARD not approved for any JIA category.

RESULTS

At CCHMC, 829 of 1,599 JIA patients (52%) were treated with ≥1 bDMARD, and 304 (19%) had been exposed to ≥1 unapproved bDMARD. In the CARRA Registry, 4,766 of 7,379 children (65%) had received ≥1 bDMARD, and 1,122 (15%) had been prescribed ≥1 unapproved bDMARD. Of those children treated with ≥2 bDMARDs for whom complete data were available, 52% (255 of 487) at CCHMC and 45% (527 of 1,159) in the CARRA Registry had chronically uncontrolled JIA despite the use of ≥2 bDMARDs.

CONCLUSION

Despite the availability of bDMARDs currently approved for JIA, there is persistent need for additional therapies to control JIA signs and symptoms. Since FDA approval is critical to ensure access to bDMARDs, the study and licensing of new medications is critical to address the unmet medication need and to further improve JIA outcomes.

Calcinosis Biomarkers in Adult and Juvenile Dermatomyositis

Dermatomyositis (DM) is a rare idiopathic inflammatory myopathy characterized by muscle weakness and cutaneous manifestations in adults and children. Calcinosis, a complication of DM, is the abnormal deposition of insoluble calcium salts in tissues, including skin, subcutaneous tissue, tendons, fascia, and muscle. Calcinosis is more commonly seen in juvenile DM (JDM), but also develops in adult DM. Although the mechanism of calcinosis remains unclear, several pathogenic hypotheses have been proposed, including intracellular accumulation of calcium secondary to an alteration of the cellular membrane by trauma and inflammation, local vascular ischemia, dysregulation of mechanisms controlling the deposition and solubility of calcium and phosphate, and mitochondrial damage of muscle cells. Identifying calcinosis biomarkers is important for early disease detection and risk assessment, and may lead to novel therapeutic targets for the prevention and treatment of DM-associated calcinosis. In this review, we summarize myositis autoantibodies associated with calcinosis in DM, histopathology and chemical composition of calcinosis, genetic and inflammatory markers that have been studied in adult DM and JDM-associated calcinosis, as well as potential novel biomarkers.

Expression of interferon-regulated genes in juvenile dermatomyositis versus Mendelian autoinflammatory interferonopathies

Background

Juvenile dermatomyositis (JDM) is a systemic autoimmune disease with a prominent interferon (IFN) signature, but the pathogenesis of JDM and the etiology of its IFN signature remain unknown. The Mendelian autoinflammatory interferonopathies, Chronic Atypical Neutrophilic Dermatosis with Lipodystrophy and Elevated temperature (CANDLE) and STING-Associated Vasculopathy with onset in Infancy (SAVI), are caused by genetic mutations and have extremely elevated IFN signatures thought to drive pathology. The phenotypic overlap of some clinical features of CANDLE and SAVI with JDM led to the comparison of a standardized interferon-regulated gene score (IRG-S) in JDM and myositis-specific autoantibody (MSA) JDM subgroups, with CANDLE and SAVI.

Methods

A peripheral 28-component IRG-S assessed by NanoString™ in 57 JDM patients subtyped by MSA was compared with IRG-S in healthy controls (HC) and CANDLE/SAVI patients. Principal component analysis (PCA) was performed, and individual genes were evaluated for their contribution to the score. IRG-S were correlated with disease assessments and patient characteristics.

Results

IRG-S in JDM patients were significantly higher than in HC but lower than in CANDLE or SAVI. JDM IRG-S overlapped more with SAVI than CANDLE by PCA. Among MSA groups, anti-MDA5 autoantibody-positive patients’ IRG-S overlapped most with SAVI. The IFI27 proportion was significantly higher in SAVI and CANDLE than JDM, but IFIT1 contributed more to IRG-S in JDM. Overall, the contribution of individual interferon-regulated genes (IRG) in JDM was more similar to SAVI. IRG-S correlated moderately with JDM disease activity measures (r_s = 0.33–0.47) and more strongly with skin activity (r_s = 0.58–0.79) in anti-TIF1 autoantibody-positive patients. Weakness and joint disease activity (multinomial OR 0.91 and 3.3) were the best predictors of high IRG-S.

Conclusions

Our findings demonstrate peripheral IRG expression in JDM overlaps with monogenic interferonopathies, particularly SAVI, and correlates with disease activity. Anti-MDA5 autoantibody-positive JDM IRG-S were notably more similar to SAVI. This may reflect both a shared IFN signature, which is driven by IFN-β and STING pathways in SAVI, as well as the shared phenotype of vasculopathy in SAVI and JDM, particularly in anti-MDA5 autoantibody-positive JDM, and indicate potential therapeutic targets for JDM.

Using the circulating proteome to assess type I interferon activity in systemic lupus erythematosus

Type I interferon (IFN) drives pathology in systemic lupus erythematosus (SLE) and can be tracked via IFN-inducible transcripts in blood. Here, we examined whether measurement of circulating proteins, which enter the bloodstream from inflamed tissues, also offers insight into global IFN activity. Using a novel protocol we generated 1,132 aptamer-based protein measurements from anti-dsDNA^pos SLE blood samples and derived an IFN protein signature (IFNPS) that approximates the IFN 21-gene signature (IFNGS). Of 82 patients with SLE, IFNPS was elevated for 89% of IFNGS-high patients (49/55) and 26% of IFNGS-low patients (7/27). IFNGS-high/IFNPS-high patients exhibited activated NK, CD4, and CD8 T cells, while IFNPS-high only patients did not. IFNPS correlated with global disease activity in lymphopenic and non-lymphopenic patients and decreased following type I IFN neutralisation with anifrolumab in the SLE phase IIb study, MUSE. In summary, we developed a protein signature that reflects IFNGS and identifies a new subset of patients with SLE who have IFN activity.

Neutrophil dysregulation is pathogenic in idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM) are characterized by muscle inflammation and weakness, myositis-specific autoantibodies (MSAs), and extramuscular organ damage. The role of neutrophil dysregulation and neutrophil extracellular traps (NETs) in IIM is unclear. We assessed whether pathogenic neutrophil subsets (low-density granulocytes [LDGs]) and NETs were elevated in IIM, associated with clinical presentation and MSAs, and their effect on skeletal myoblasts and myotubes. Circulating NETs and LDGs were quantified and correlated with clinical measures. Specific MSAs were tested for their ability to induce NETs. NETs and neutrophil gene expression were measured in IIM biopsies. Whether NETs damage skeletal myoblasts and myotubes was tested. Circulating LDGs and NETs were increased in IIM. IIM LDGs had an enhanced ability to form NETs. LDGs and NETs correlated with IIM disease activity and muscle damage. The serum MSA anti-MDA5 correlated with circulating and tissue NETs and directly enhanced NET formation. An enhanced neutrophil gene signature was present in IIM muscle and associated with muscle injury and tissue IFN gene signatures. IIM NETs decreased the viability of myotubes in a citrullinated histone-dependent manner. Dysregulated neutrophil pathways may play pathogenic roles in IIM through their ability to directly injure muscle cells and other affected tissues.

Long-term outcomes in Juvenile Myositis patients

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Endothelial Activation Markers as Disease Activity and Damage Measures in Juvenile Dermatomyositis

OBJECTIVE

Circulating endothelial cells (CEC), von Willebrand factor (vWF) antigen, P-selectin, and thrombomodulin are released from damaged endothelium, while decreases in circulating endothelial progenitor cells (CEPC) have been associated with poor vascular outcomes. We examined these markers in the peripheral blood of patients with juvenile dermatomyositis (JDM) and their correlations with disease assessments.

METHODS

Peripheral blood endothelial cells and biomarkers were assessed in 20 patients with JDM and matched healthy controls. CEC and CEPC were measured by flow cytometry, while vWF antigen and activity, factor VIII, P-selectin, and thrombomodulin were measured in plate-based assays. Disease activity and damage, nailfold capillary density, and brachial artery flow dilation were assessed. Serum cytokines/chemokines were measured by Luminex.

RESULTS

CEC, vWF antigen, factor VIII, and thrombomodulin, but not vWF activity, CEPC, or P-selectin, were elevated in the peripheral blood of patients with JDM. CEC correlated with pulmonary activity (r_s = 0.56). The vWF antigen correlated with Patient's/Parent's Global, cutaneous, and extramuscular activity (r_s = 0.47-0.54). CEPC negatively correlated with muscle activity and physical function (r_s = -0.52 to -0.53). CEPC correlated inversely with endocrine damage. The vWF antigen and activity correlated with interleukin 10 and interferon-gamma inducible protein-10 (r_s = 0.64-0.82).

CONCLUSION

Markers of endothelial injury are increased in patients with JDM and correlate with extramuscular activity. CEPC correlate inversely with muscle activity, suggesting a functional disturbance in repair mechanisms.

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.

Anti-Ro52 autoantibodies are associated with interstitial lung disease and more severe disease in patients with juvenile myositis

OBJECTIVES

Anti-Ro52 autoantibodies are associated with more severe interstitial lung disease (ILD) in adult myositis patients with antiaminoacyl transfer (t)RNA synthetase autoantibodies. However, few studies have examined anti-Ro52 autoantibodies in juvenile myositis. The purpose of this study was to define the prevalence and clinical features associated with anti-Ro52 autoantibodies in a large cohort of patients with juvenile myositis.

METHODS

We screened sera from 302 patients with juvenile dermatomyositis (JDM), 25 patients with juvenile polymyositis (JPM) and 44 patients with juvenile connective tissue disease-myositis overlap (JCTM) for anti-Ro52 autoantibodies by ELISA. Clinical characteristics were compared between myositis patients with and without anti-Ro52 autoantibodies.

RESULTS

Anti-Ro52 autoantibodies were found in 14% patients with JDM, 12% with JPM and 18% with JCTM. Anti-Ro52 autoantibodies were more frequent in patients with antiaminoacyl tRNA synthetase (64%, p<0.001) and anti-MDA5 (31%, p<0.05) autoantibodies. After controlling for the presence of myositis-specific autoantibodies, anti-Ro52 autoantibodies were associated with the presence of ILD (36% vs 4%, p<0.001). Disease course was more frequently chronic, remission was less common, and an increased number of medications was received in anti-Ro52 positive patients.

CONCLUSIONS

Anti-Ro52 autoantibodies are present in 14% of patients with juvenile myositis and are strongly associated with anti-MDA5 and antiaminoacyl tRNA synthetase autoantibodies. In all patients with juvenile myositis, those with anti-Ro52 autoantibodies were more likely to have ILD. Furthermore, patients with anti-Ro52 autoantibodies have more severe disease and a poorer prognosis.

Features distinguishing clinically amyopathic juvenile dermatomyositis from juvenile dermatomyositis

Objective

We examined features of clinically amyopathic JDM (CAJDM), in which patients have characteristic rashes with little to no evidence of muscle involvement, to determine whether this is a distinct phenotype from JDM.

Methods

Demographic, clinical, laboratory and treatment data from 12 (9 hypomyopathic, 3 amyopathic) patients meeting modified Sontheimer criteria for CAJDM and from 60 matched JDM patients meeting Bohan and Peter criteria were examined. Differences were evaluated by Fisher's exact and Mann-Whitney tests, random forests and logistic regression analysis.

Results

Nine (75%) CAJDM patients had anti-p155/140 (transcriptional intermediary factor 1), one (8.3%) anti-melanoma differentiation-associated gene 5 autoantibodies and two (16.7%) were myositis autoantibody negative. CAJDM patients were younger at diagnosis and frequently had mild disease at onset. CAJDM patients had less frequent myalgias, arthritis, contractures, calcinosis, dysphagia, abdominal pain and fatigue. The muscle, skeletal and overall clinical scores were lower in CAJDM. Serum muscle enzymes were less frequently increased in CAJDM, and peak values were lower. CAJDM patients received fewer medications compared with JDM patients. Only 50% of CAJDM patients received oral prednisone, but the maximum dose and treatment duration did not differ from JDM. At a median follow-up of 2.9 years, CAJDM patients had no documented functional disability, and none developed weakness, calcinosis, interstitial lung disease or lipodystrophy. Multivariable modelling revealed a lower skeletal score and less frequent myalgias as the most important factors in distinguishing CAJDM from JDM.

Conclusion

CAJDM may be distinguished from JDM, in that they often have p155/140 (transcriptional intermediary factor 1) autoantibodies, have fewer systemic manifestations and receive less therapy.