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An update on juvenile dermatomyositis
1Northwestern University Medical School, Chicago, Illinois, USA.
Abstract:
Juvenile dermatomyositis (JDMS) is a systemic vasculopathy characterized primarily by inflammation of skin and muscle. JDMS is identified in more than three per million persons per year, using established diagnostic criteria. Although originally thought to be a relatively homogeneous disease, new data confirm that heterogeneity in JDMS may be found at several levels and that each variant may be associated with a different disease course. Unlike adults with dermatomyositis, of whom more than 50% have a specific myositis-associated antibody (MSA), a much smaller number of children appear to test positive for a known MSA (about 10%), despite the evidence that more than 60% of children with JDMS test positive for antinuclear antibodies. In children, the most common MSA is directed against Mi-2, not toward one of the tRNA synthetases, such as tRNA histidine, as is found in 20% to 30% of adults with myositis. About 50% of children with JDMS have circulating evidence of endothelial cell damage (increased vWF:Ag), whereas others have different indicators of disease activity, such as elevated neopterin (> 60%) or increased circulating B cells with peripheral lymphopenia (> 80%). Newer modes of assessment of functional ability may help evaluate response to therapy. Finally, physicians with newly diagnosed (< 6 months) JDMS patients are urged to call the new National Institutes of Health Rare Disease Registry for New Onset Dermatomyositis (312-880-3333) to enroll their patients and for more information on the onset of this disease.
Insights
Juvenile dermatomyositis (JDMS) is a rare autoimmune disease affecting children, showing significant heterogeneity. Research highlights distinct antibody profiles and biomarkers in JDMS, differing from adult forms, impacting disease course and treatment.
Area of Science:
- Rheumatology
- Pediatrics
- Immunology
Background:
- Juvenile dermatomyositis (JDMS) is a rare systemic vasculopathy causing skin and muscle inflammation.
- JDMS incidence is over three per million children annually.
- Previously considered homogeneous, JDMS is now recognized for its heterogeneity, influencing disease progression.
Purpose of the Study:
- To explore the heterogeneity of Juvenile Dermatomyositis (JDMS).
- To compare antibody profiles and biomarkers in pediatric JDMS with adult dermatomyositis.
- To identify distinct indicators of disease activity and endothelial damage in JDMS.
Main Methods:
- Analysis of myositis-associated antibody (MSA) prevalence in pediatric JDMS patients.
- Assessment of antinuclear antibody (ANA) positivity in children with JDMS.
- Measurement of endothelial cell damage markers (e.g., vWF:Ag), neopterin, and B cell counts in JDMS patients.
Main Results:
- Only about 10% of children with JDMS test positive for known MSAs, contrasting with over 50% in adults.
- Over 60% of children with JDMS are ANA-positive.
- The most common MSA in children is anti-Mi-2, unlike adults where tRNA synthetase antibodies are more frequent.
- Endothelial damage markers (vWF:Ag) are elevated in ~50% of JDMS patients, with others showing elevated neopterin or B cell changes.
Conclusions:
- JDMS exhibits significant heterogeneity in antibody profiles and biomarkers.
- Pediatric JDMS differs from adult dermatomyositis in MSA prevalence and types.
- Distinct biomarkers indicate varied disease activity and endothelial involvement in JDMS, suggesting different disease subtypes.
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