Abstract
Easily accessible biomarkers are urgently needed to evaluate immune activation in Juvenile Dermatomyositis (JDM). The goal of this retrospective study is to define immunological and clinical differences between untreated JDM patients with either normal or elevated (>10 mmol/L) levels of neopterin, a biomarker of macrophage activation. We included all JDM with neopterin data obtained before initiating medical therapy. We assessed T, B, NK cell populations, muscle enzymes, and disease activity scores for skin (sDAS), muscle (mDAS), total (tDAS), the duration of untreated disease, disease course, and myositis-specific antibody (MSA). Seventy-nine percent of 139 untreated JDM patients had elevated serum neopterin. The group with elevated neopterin had significantly more active disease: tDAS 11.9 vs. 8.1 (p < 0.0001), mDAS 5.8 vs. 3.1 (p < 0.0001), sDAS 6.1 vs. 4.9 (p = 0.0002), aldolase 24.0 vs. 7.6 U/L (p < 0.0001), von Willebrand factor antigen (p < 0.0001), and ESR 19.8 vs. 11.5 mm/hr (p = 0.01). The flow cytometry documented both reduced T cells (1494 vs. 2278/mm3, p = 0.008) and NK cells (145 vs. 240/mm3, p = 0.003). TNFα-308AA/AG polymorphism was more common in children with elevated neopterin than TNFα-308GG (p 0.05). We conclude that the availability of neopterin data will contribute to the rapid assessment of untreated JDM disease activity.
Highlights
Our recent RNA-Seq studies documented that children with Juvenile Dermatomyositis (JDM) appear to have inactive disease, prompting reduction of medication, they have upregulated transcriptional activity [1]
Neopterin is a metabolic product of guanosine triphosphate, which is produced by macrophages upon stimulation with interferon-gamma (IFN-γ) from activated T helper-1 cells (Th1) [2]
The median neopterin level was 17.1 nmol/L with levels ranging from 2.4 nmol/L up to 68.4 nmol/L
Summary
Our recent RNA-Seq studies documented that children with JDM appear to have inactive disease, prompting reduction of medication, they have upregulated transcriptional activity [1]. The degree of macrophage activation can be assessed by measuring neopterin in body fluids such as serum, urine, synovial fluid, or cerebrospinal fluid [3,4]. Increased serum neopterin level is seen in hemophagocytic lymphohistiocytosis syndrome, chronic infection, and autoimmune disease [2,5,6,7]. Juvenile Dermatomyositis (JDM) is a rare pediatric systemic autoimmune disease characterized by skin rash and muscle damage [8]. The diagnosis of JDM was made based on the
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