Gene expression profiling in neutrophils from children with polyarticular juvenile idiopathic arthritis

Objective

We have previously reported a defect in neutrophil activation in children with polyarticular juvenile idiopathic arthritis (JIA). The current study was undertaken to determine whether gene expression abnormalities persist in JIA in remission and to use systems biology analysis to elucidate pathologic pathways in polyarticular JIA.

Methods

We performed gene expression profiling on neutrophils from children with polyarticular JIA. Children were grouped according to disease status. We studied 14 children with active disease who were taking medication, 8 children with clinical remission of disease who were taking medication (CRM status), and 6 children with clinical remission of disease who were not taking medication (CR status). We also studied 13 healthy children whose age ranges overlapped those of the patients.

Results

Neutrophil abnormalities persisted in children with polyarticular JIA even after disease remission was achieved. Children with active disease and those with CRM status showed no differences in expression of specific genes, although they could be separated on cluster analysis. A comparison of children with CR status and healthy control children revealed networks of pro‐ and antiinflammatory genes that suggested that remission is a state of homeostasis and balance rather than a return to normal immune function. Furthermore, gene overexpression in patients with CR status supports the hypothesis that neutrophils play a role in regulating adaptive immunity in this disease.

Conclusion

Neutrophil gene profiling in polyarticular JIA suggests important roles for neutrophils in disease pathogenesis. These findings suggest the presence of complex interactions between innate and adaptive immunity, that are not easily modeled in conventional, linear, reductionist systems.

     

Interleukin-33 as a marker of disease activity in rheumatoid factor positive polyarticular juvenile idiopathic arthritis

Objective: To investigate clinical usefulness of serum interleukin (IL)-33 levels as an indicator of disease activity in juvenile idiopathic arthritis (JIA).

Methods: We measured serum levels of IL-33 in 39 patients with JIA, including 7 patients with rheumatoid factor positive poly-JIA (RF?+?poly-JIA), 8 patients with RF negative poly-JIA (RF-poly-JIA), 20 patients with oligoarticular JIA (Oligo-JIA), 4 patients with enthesitis-related arthritis (ERA) and 30 age-matched healthy controls. Furthermore, we determined their correlation with measures of disease activity.

Results: Serum IL-33 levels in patients with RF?+?poly-JIA were significantly elevated compared to those in patients with RF-poly-JIA, oligo-JIA and HC. Serum IL-33 levels in patients with RF-poly-JIA, oligo-JIA and ERA were not elevated compared to those in HC. Serum IL-33 levels in RF?+?poly-JIA patients normalized in remission phase. Serum IL-33 levels correlated positively with RF in patients with RF?+?poly-JIA.

Conclusions: These results indicate that serum IL-33 levels in RF?+?poly-JIA patients correlated with disease activity, suggesting a potential role of IL-33 as a promising indicator of disease activity.     

Successful treatment of refractory polyarticular juvenile idiopathic arthritis with rituximab

SIR, Juvenile idiopathic arthritis (JIA), being the most commonchronic musculoskeletal disease of childhood, has a prevalenceestimated to be 1 in 1000 children [1]. Up to 10% of these remainseverely disabled in adulthood [2]. Numerous disease-modifyinganti-rheumatic drugs (DMARDs) have been trialled with varyingsuccess in JIA, and therefore additional therapeutic targetshave been investigated. Pro-inflammatory cytokines have beenimplicated in the pathogenesis of JIA especially tumour necrosisfactor- (TNF-), interleukin-1 (IL-1) and IL-6. Biological     

Therapeutic experience with infliximab in a patient with polyarticular juvenile idiopathic arthritis and uveitis

A pediatric patient with prolonged seronegative polyarticular juvenile idiopathic arthritis (JIA) and concomitant aggressive, anterior uveitis refractory to any conventional antirheumatic therapy was treated with infliximab. Arthritis and C-reactive protein (CRP) values showed prompt positive effects but, after 6 weeks, returned gradually to initial values despite ongoing therapy. In contrast, a more sustained therapeutic effect was observed on the uveitis, with increased visual acuity and reduced inflammatory signs of the affected eye. However, this benefit was also lost at week 30, after which infliximab had to be discontinued due to side effects. To conclude, in polyarticular seronegative JIA, infliximab showed a transient beneficial effect which was more pronounced on uveitis than arthritis.     

Outcome status in children with sustained polyarticular and systemic juvenile idiopathic arthritis

SIR, Juvenile idiopathic arthritis (JIA) is the most commonrheumatic disease of childhood and an important cause of disability[1]. The reported outcome of JIA varies substantially [2–4].Traditionally, measurement of outcome has focused predominantlyon measurements of disease activity such as erythrocyte sedimentationrate (ESR) and an active joint count. Recent investigationshave highlighted the limitations of such measures [5]. Additionalfunctional outcome scales were introduced, such as the ChildhoodHealth Assessment Questionnaire (CHAQ), the Juvenile ArthritisFunctional Assessment Scale (JAFAS) and the Juvenile ArthritisFunctional Assessment Report (JAFAR). At     

HLA-DRB typing among polyarticular juvenile idiopathic arthritis and progressive pseudorheumatoid dysplasia patients

Juvenile Idiopathic Arthritis (JIA) is a multi-factorial disease influenced both by environmental and genetic factors. Progressive pseudorheumatoid dysplasia (PPD) is a rare autosomal recessive genetic disorder affecting multiple joints, mimicking JIA. Aim of the work: to reveal the frequency of HLA-DR types among the studied patients and to correlate the different allele variations clinically. Patients and methods: Thirty JIA patients, in addition to 15 molecularly diagnosed PPD patients were subjected to full history taking and clinical examination. HLA-DRB1 typing was performed to 24/30 JIA and 12/15 PPD cases and thirty healthy age and sex matched children who were included as a control group. Results: The JIA patients were 22 females and 8 males with mean age of 15.8 ± 1.96 years and disease duration 5.3 ± 4.4 years. PPD patients were 8 males and 7 females with mean age of 8.7 ± 3.06 years and disease duration 3.95 ± 2.68 years. A significant frequency of HLA-DRB 04 (p = 0.049) among JIA patients was present in comparison to the controls (OR = 2.81, CI:1.02–7.75), other risky alleles were HLA-DRB 10, 13 and 15. However, HLA-DRB 01, 03, 07, 11 and 14 were found to be protective. HLA-DRB 01, 04, 10 and 13 were found to be risky alleles in PPD. However, HLA 03, 07, 11 and 15 were found to be protective alleles among PPD patients. Conclusion: HLA-DRB 04 was found in a higher frequency in JIA patients with a significant difference in comparison to the controls, denoting that it may play a role in the genetic pathogenesis of JIA.     

Therapeutic use of etanercept in polyarticular course juvenile idiopathic arthritis over a two year period

OBJECTIVE: To analyse the treatment response to etanercept in patients with polyarticular course juvenile idiopathic arthritis (JIA). METHODS: 22 patients with polyarticular course JIA (19 females, three males; mean age 13.9 years; mean disease duration 6.3 years; 15 with polyarticular onset, seven with systemic onset, one with residual systemic activity; eight rheumatoid factor positive; eight with erosive disease) were treated with etanercept for up to 24 months. Etanercept was given subcutaneously at 0.4 mg/kg twice a week. Treatment response was ascertained in an open prospective study. RESULTS: All patients showed impressive clinical improvement, with a decrease in swollen joint count by an average of 10.1 joints (mean of 49% decrease), a decrease in tender joint count by 9.3 joints (mean of 94%), and decrease in total joint count by 11.2 joints (mean of 48%). Duration of morning stiffness decreased to less than 10 minutes. Furthermore, haemoglobin concentration increased on average by 14 g/l (mean of 15.3%) and packed cell volume increased by 0.035 (mean increase of 12%), and erythrocyte sedimentation rate decreased on average by 42.8 mm/1st h (mean decrease of 64%). No major side effects were noted. CONCLUSION: Etanercept continues to be clinically effective and well tolerated in patients with polyarticular course JIA over a two year period.     

HLA antigens in juvenile arthritis. Pauciarticular and polyarticular juvenile arthritis are immunogenetically distinct

Using DNA techniques, we investigated the role of HLA-DR, DQ, and DP alleles in susceptibility to juvenile arthritis (JA). We studied 2 groups of patients with JA having a different disease prognosis and course. The pauciarticular form is usually benign, while the polyarticular disease frequently leads to joint destruction and disability. Persistent pauciarticular disease developed preferentially in patients having HLA-DRw13-Dw18 and DQw6-Dw18, but these antigens did not confer susceptibility in patients whose disease converted to the polyarticular form. HLA-DPw2.1 was an additional susceptibility factor for patients with JA of pauciarticular onset. In the polyarticular form of JA, HLA-DPw3 was the major factor for susceptibility, giving a relative risk of 10.3 (P less than 0.0001). In addition, we found that DRw8.1 and DQw4 were increased, and HLA-DR4 was markedly decreased, in patients with pauciarticular and polyarticular disease. These results indicate that in addition to some shared factors, distinct HLA class II alleles are important in pauciarticular or polyarticular JA. We conclude that typing with oligonucleotide probes may be useful in predicting the outcome in some children with arthritis.     

Biologic similarities based on age at onset in oligoarticular and polyarticular subtypes of juvenile idiopathic arthritis

Objective

To explore biologic correlates to age at onset in patients with juvenile idiopathic arthritis (JIA) using peripheral blood mononuclear cell (PBMC) gene expression analysis.

Methods

PBMCs were isolated from 56 healthy controls and 104 patients with recent‐onset JIA (39 with persistent oligoarticular JIA, 45 with rheumatoid factor–negative polyarticular JIA, and 20 with systemic JIA). RNA was amplified and labeled using NuGEN Ovation, and gene expression was assessed with Affymetrix HG‐U133 Plus 2.0 GeneChips.

Results

A total of 832 probe sets revealed gene expression differences (false discovery rate 5%) in PBMCs from children with oligoarticular JIA whose disease began before age 6 years (early‐onset disease) compared with those whose disease began at or after age 6 years (late‐onset disease). In patients with early‐onset disease, there was greater expression of genes related to B cells and less expression of genes related to cells of the myeloid lineage. Support vector machine analyses identified samples from patients with early‐ or late‐onset oligoarticular JIA (with 97% accuracy) or from patients with early‐ or late‐onset polyarticular JIA (with 89% accuracy), but not from patients with systemic JIA or healthy controls. Principal components analysis showed that age at onset was the major classifier of samples from patients with oligoarticular JIA and patients with polyarticular JIA.

Conclusion

PBMC gene expression analysis reveals biologic differences between patients with early‐and late‐onset JIA, independent of classification based on the number of joints involved. These data suggest that age at onset may be an important parameter to consider in JIA classification. Furthermore, pathologic mechanisms may vary with age at onset, and understanding these processes may lead to improved treatment of JIA.

     

Differential plasma microRNAs expression in juvenile idiopathic arthritis

Objectives. To identify potential novel biomarkers for juvenile idiopathic arthritis (JIA), we evaluated the correlation between plasma expression levels of specific miRNAs and disease characteristics of JIA.

Methods. Differentially expressed miRNAs in JIA plasma were identified by microarray analysis. Five candidate plasma miRNAs with differential expression were further evaluated by qRT-PCR. The correlation between the expression of candidate plasma miRNAs and clinical parameters of JIA patients was assessed.

Results. The expression of miR-16, miR-146a, and miR-223 was higher, and miR-132 was lower, in the plasma of JIA patients as compared with healthy subjects and juvenile ankylosing spondylitis patients (p < 0.05). Plasma miR-16 concentrations were considerably higher for polyarticular JIA patients than oligoarticular JIA patients and correlated with the juvenile arthritis magnetic resonance imaging scores for the hip and plasma interleukin-6 or IL-6 levels. Additionally, miR-146a levels correlated directly with the Juvenile Arthritis Disease Activity Scores in 27 joints, the swollen joint count, the limited joint count, and the juvenile arthritis magnetic resonance imaging scores for the hip, but correlated inversely with plasma tumor necrosis factor-α or TNF-α levels.

Conclusions. This study demonstrates that the expression of plasma miRNAs correlates with JIA disease and suggests that plasma miR-16 and miR-146a have potential novel value for JIA diagnosis.     

Effect of age on prevalence of anticitrullinated protein/peptide antibodies in polyarticular juvenile idiopathic arthritis

OBJECTIVES: Anticitrullinated protein/peptide antibodies (ACPA) have an excellent diagnostic performance for rheumatoid arthritis (RA). Despite similarities between RA and polyarticular juvenile idiopathic arthritis (JIA), the prevalence of ACPA in polyarticular JIA is low. We wanted to evaluate the influence of age, disease duration and total immunoglobulin G (IgG) concentration on ACPA positivity in this cohort. METHODS: Patients with JIA were classified according to age and International League of Associations for Rheumatology classification. Sixty-one JIA patients aged less than 16 yr were included and classified as polyarticular JIA (poly JIA <16; n=23) or non-polyarticular JIA (n=38). In addition, a group of 21 polyarticular JIA patients, aged more than 16 yr (poly JIA >16) and a group of 51 RA patients were included. Antibodies to the synthetic citrullinated peptides pepA and pepB were detected by line immunoassay and antibodies to cyclic citrullinated peptides (CCP2) by enzyme-linked immunosorbent assay. Serum IgG was measured by fixed-time immunonephelometry. RESULTS: No ACPA reactivity was observed in the non-polyarticular group. In poly JIA <16, only 1/23 had anti-CCP2 antibody, whereas in poly JIA >16 patients a significantly higher fraction was detected (6/21). All but one of the anti-CCP2 reactive patients were rheumatoid factor (RF) positive. Assessing anti-CCP2 antibody concentration as a continuous variable, significantly higher titres were found in poly JIA >16 compared with poly JIA <16. No correlation between anti-CCP2 concentration and total IgG was detected. Four patients demonstrated immunoreactivity against pepA and pepB; all of them were anti-CCP2 reactive, poly JIA >16 patients. CONCLUSIONS: ACPA are present in low prevalence in polyarticular JIA and are particularly found in the RF-positive subset. With age, a significant increase in anti-CCP2 positivity is observed in polyarticular JIA patients.