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Objective: To determine whether aggressive treatment initiated early in the course of rheumatoid factor (RF)-positive or RF-negative polyarticular juvenile idiopathic arthritis (JIA) can induce clinical inactive disease within 6 months., Methods: Between May 2007 and October 2010, a multicenter, prospective, randomized, double-blind, placebo-controlled trial of 2 aggressive treatments was conducted in 85 children ages 2-16 years with polyarticular JIA of <12 months' duration. Patients received either methotrexate (MTX) 0.5 mg/kg/week (maximum 40 mg) subcutaneously, etanercept 0.8 mg/kg/week (maximum 50 mg), and prednisolone 0.5 mg/kg/day (maximum 60 mg) tapered to 0 by 17 weeks (arm 1), or MTX (same dosage as arm 1), etanercept placebo, and prednisolone placebo (arm 2). The primary outcome measure was clinical inactive disease at 6 months. An exploratory phase determined the rate of clinical remission on medication (6 months of continuous clinical inactive disease) at 12 months., Results: By 6 months, clinical inactive disease had been achieved in 17 (40%) of 42 patients in arm 1 and 10 (23%) of 43 patients in arm 2 (χ(2) = 2.91, P = 0.088). After 12 months, clinical remission on medication was achieved in 9 patients in arm 1 and 3 patients in arm 2 (P = 0.053). There were no significant interarm differences in adverse events., Conclusion: Although this study did not meet its primary end point, early aggressive therapy in this cohort of children with recent-onset polyarticular JIA resulted in clinical inactive disease by 6 months and clinical remission on medication within 12 months of treatment in substantial proportions of patients in both arms., (Copyright © 2012 by the American College of Rheumatology.)

Objective: To determine whether peripheral blood mononuclear cells (PBMCs) from children with recent-onset polyarticular juvenile idiopathic arthritis (JIA) exhibit biologically or clinically informative gene expression signatures., Methods: Peripheral blood samples were obtained from 59 healthy children and 61 children with polyarticular JIA prior to treatment with second-line medications, such as methotrexate or biologic agents. RNA was extracted from isolated mononuclear cells, fluorescence labeled, and hybridized to commercial gene expression microarrays (Affymetrix HG-U133 Plus 2.0). Data were analyzed using analysis of variance at a 5% false discovery rate threshold after robust multichip analysis preprocessing and distance-weighted discrimination normalization., Results: Initial analysis revealed 873 probe sets for genes that were differentially expressed between polyarticular JIA patients and healthy controls. Hierarchical clustering of these probe sets distinguished 3 subgroups within the polyarticular JIA group. Prototypical patients within each subgroup were identified and used to define subgroup-specific gene expression signatures. One of these signatures was associated with monocyte markers, another with transforming growth factor beta-inducible genes, and a third with immediate early genes. Correlation of gene expression signatures with clinical and biologic features of JIA subgroups suggested relevance to aspects of disease activity and supported the division of polyarticular JIA into distinct subsets., Conclusion: Gene expression signatures in PBMCs from patients with recent-onset polyarticular JIA reflect discrete disease processes and offer a molecular classification of disease.

Objective: To identify differences in peripheral blood gene expression between patients with different subclasses of juvenile idiopathic arthritis (JIA) and healthy controls in a multicenter study of patients with recent-onset JIA prior to treatment with disease-modifying antirheumatic drugs (DMARDs) or biologic agents., Methods: Peripheral blood mononuclear cells (PBMCs) from 59 healthy children and 136 patients with JIA (28 with enthesitis-related arthritis [ERA], 42 with persistent oligoarthritis, 45 with rheumatoid factor [RF]-negative polyarthritis, and 21 with systemic disease) were isolated from whole blood. Poly(A) RNA was labeled using a commercial RNA amplification and labeling system (NuGEN Ovation), and gene expression profiles were obtained using commercial expression microarrays (Affymetrix HG-U133 Plus 2.0)., Results: A total of 9,501 differentially expressed probe sets were identified among the JIA subtypes and controls (by analysis of variance; false discovery rate 5%). Specifically, 193, 1,036, 873, and 7,595 probe sets were different in PBMCs from the controls compared with those from the ERA, persistent oligoarthritis, RF-negative polyarthritis, and systemic JIA patients, respectively. In patients with persistent oligoarthritis, RF-negative polyarthritis, and systemic JIA subtypes, up-regulation of genes associated with interleukin-10 (IL-10) signaling was prominent. A hemoglobin cluster was identified that was underexpressed in ERA patients but overexpressed in systemic JIA patients. The influence of JAK/STAT, ERK/MAPK, IL-2, and B cell receptor signaling pathways was evident in patients with persistent oligoarthritis. In systemic JIA, up-regulation of innate immune pathways, including IL-6, Toll-like receptor/IL-1 receptor, and peroxisome proliferator-activated receptor signaling, were noted, along with down-regulation of gene networks related to natural killer cells and T cells. Complement and coagulation pathways were up-regulated in systemic JIA, with a subset of these genes being differentially expressed in other subtypes as well., Conclusion: Expression analysis identified differentially expressed genes in PBMCs obtained early in the disease from patients with different subtypes of JIA and in healthy controls, providing evidence of immunobiologic differences between these forms of childhood arthritis.

Objective: Systemic juvenile idiopathic arthritis (JIA) is frequently associated with the development of macrophage activation syndrome. This study was undertaken to better understand the relationship between systemic JIA and macrophage activation syndrome., Methods: Gene expression profiles were examined in 17 patients with untreated new-onset systemic JIA, 5 of whom showed evidence of subclinical macrophage activation syndrome (of whom 2 eventually developed overt macrophage activation syndrome). Peripheral blood mononuclear cells (PBMCs) were separated on Ficoll gradients, and purified RNA was analyzed using Affymetrix GeneChip expression arrays. A fraction of the PBMCs were used for flow cytometry to define the cellular composition of the samples., Results: Two hundred twenty-five differentially expressed genes (P < 0.05) that distinguished patients with systemic JIA from healthy controls (n = 30) were identified. Clustering analysis indicated that expression patterns correlated with serum ferritin levels. Three main clusters distinguished systemic JIA patients with highly elevated ferritin levels (including those with subclinical macrophage activation syndrome) from those with normal or only moderately elevated ferritin levels. The first cluster comprised genes involved in the synthesis of hemoglobins and structural proteins of erythrocytes. This transcriptional profile was consistent with immature nucleated red blood cells, likely reflective of high red blood cell turnover. Also included were transcripts indicating immature granulocytes. The second cluster was enriched for genes involved in cell cycle regulation. The third cluster was enriched for genes involved in innate immune responses, including those involved in the negative regulation of Toll-like receptor/interleukin-1 receptor-triggered inflammatory cascades and markers of the alternative pathway of macrophage differentiation. Additional differentially expressed genes of interest were those involved in the cytolytic pathway, including SH2D1A and Rab27a., Conclusion: These data indicate that gene expression profiling can be a useful tool for identifying early macrophage activation syndrome in patients with systemic JIA.