Proinflammatory responses to self HLA epitopes are triggered by molecular mimicry to Epstein‐Barr virus proteins in oligoarticular juvenile idiopathic arthritis

Objective

To evaluate whether abnormal T cell recognition may be generated by exposure to exogenous antigens presenting sequence homology with epitopes contained in self HLA alleles, and if such recognition may be part of the mechanisms that fuel inflammation in autoimmune diseases associated with certain HLA alleles.

Methods

Cytotoxic responses of peripheral blood mononuclear cells to 9‐mer peptides derived from HLA molecules (DRB1*1101, DRB1*0801, or DPB1*0201) associated with oligoarticular juvenile idiopathic arthritis (JIA) or homologous peptides derived from Epstein‐Barr virus (EBV) proteins (Bolf1 or Balf2) were analyzed in patients with oligoarticular JIA and in healthy controls matched for HLA–DRB1*1101, DRB1*0801, or DPB1*0201. Production of proinflammatory cytokines in culture supernatants was determined by enzyme‐linked immunosorbent assay.

Results

T cell cytotoxic responses and production of proinflammatory cytokines in response to stimulation with self HLA–derived peptides were found only in patients with oligoarticular JIA, and not in controls. Patients with oligoarticular JIA, but none of the healthy controls, had EBV–self HLA cross‐reactive T cells.

Conclusion

Our data suggest a disease‐ and allele‐specific mechanism of autoimmunity in oligoarticular JIA. This mechanism may be part of the pathogenesis of the disease, and could be the basis of one of the likely multiple candidates for antigen‐specific immunotherapy approaches in the future.

     

Disease control and health‐related quality of life in juvenile idiopathic arthritis

Objective

To examine variability in health‐related quality of life (HRQOL) in children with juvenile idiopathic arthritis (JIA) experiencing no or minimal clinical symptoms, and in a subgroup with polyarticular JIA treated with biologic agents for 12 months.

Methods

We defined 3 samples using a database of patients ages 2–18 years with JIA (n = 524; patient visits [PV] = 2,354): visits (PV = 2,155) with no or minimal clinical symptoms on at least 1 of 4 measures (active joint count, pain, physician global disease rating, Childhood Health Assessment Questionnaire); visits (PV = 941) with no or minimal symptoms on all 4 measures; and children (n = 31) with polyarticular JIA treated with biologic agents for 12 months. HRQOL was measured using the Pediatric Quality of Life Inventory (PedsQL) and the percentage of patients with suboptimal HRQOL was determined.

Results

In PV with a PedsQL score, suboptimal HRQOL by self‐report occurred in 362 (20.6%) PV with at least 1 indicator of minimal symptoms, and in 64 (7.9%) PV with all 4 measures indicating minimal symptoms (519 [25.7%] and 95 [10.7%], respectively, by parent report). For children with polyarticular JIA treated for 12 months with biologic agents, 7 (25.9%) patients by self‐report and 10 (35.7%) patients by parent report were in the suboptimal range of HRQOL.

Conclusion

A substantial percentage of patients with JIA who report no or mild clinical symptoms experience suboptimal HRQOL. This is also true for patients with polyarticular JIA treated with biologic agents for 12 months. Although disease activity and clinical symptoms are related to HRQOL, considerable unexplained variation in HRQOL exists. HRQOL needs to be assessed independently regardless of clinical status.

     

Gene expression signatures in polyarticular juvenile idiopathic arthritis demonstrate disease heterogeneity and offer a molecular classification of disease subsets

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 β–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.

     

Synovial fluid proteins differentiate between the subtypes of juvenile idiopathic arthritis

Objective

Juvenile idiopathic arthritis (JIA) is a heterogeneous group of inflammatory diseases, and no clinically useful prognostic markers to predict disease outcome in children with JIA are currently available. Synovial fluid likely reflects the proteins present in the inflamed synovium. The purpose of this study was to delineate the synovial fluid proteome and determine whether protein expression differs in the different subtypes of JIA.

Methods

Synovial fluid samples obtained from children with oligoarticular JIA, polyarticular JIA, or systemic JIA were compared. Two‐dimensional gel electrophoresis for protein separation and matrix‐assisted laser desorption ionization−time‐of‐flight mass spectrometry and quadripole time‐of‐flight mass spectrometry for protein identification were used for this study. Synovial fluid cells were analyzed by polymerase chain reaction (PCR) for the presence of haptoglobin messenger RNA (mRNA).

Results

The synovial fluid proteome of the samples was delineated. The majority of proteins showed overexpression in JIA synovial fluid as compared with noninflammatory control samples. There were 24 statistically significantly differentially expressed spots (>2‐fold change; P < 0.05) between the subtypes of JIA. PCR analysis revealed haptoglobin mRNA, suggesting that haptoglobin is locally produced in an inflamed joint in JIA.

Conclusion

Despite the similar histologic appearance of inflamed joints in patients with different subtypes of JIA, there are differences in protein expression according to the subtype of JIA. Haptoglobin is differentially expressed between the subtypes of JIA and is locally produced in an inflamed joint in JIA. Haptoglobin and other differentially expressed proteins may be potential biomarkers in JIA.

     

Arthritis beliefs and self‐care in an urban American Indian population

Objective

To describe beliefs and self‐care strategies of American Indians with chronic arthritis joint pain.

Method

In‐depth interviews were conducted with a convenience sample of urban‐dwelling American Indians (n = 56) concerning self‐care and beliefs about arthritis; objective measures of arthritis disease activity were obtained through standardized interview protocols.

Results

Joint pain was not generally assumed to be arthritis nor directly related to aging. Belief that chronic pain affecting multiple joints was a serious and unexpected condition oriented American Indians' decisions to seek medical attention. However, verbal communications about pain may be subtle or under emphasized. Few coping strategies were used to control either chronic or episodic pain.

Conclusions

Chronic arthritis pain may not be optimally managed in this population. Cultural assessment should recognize that American Indian patients may understate serious symptoms. Community educational interventions should target this population to enhance self‐care, pain management, and communication of arthritis symptoms to physicians.

     

Ongoing disease activity and changing categories in a long‐term nordic cohort study of juvenile idiopathic arthritis

Objective

To describe the disease characteristics, long‐term course, and outcome of patients with juvenile idiopathic arthritis (JIA) in a population‐based setting.

Methods

Consecutive cases of JIA from defined geographic areas of Denmark, Finland, Sweden, and Norway in whom disease onset occurred in 1997–2000 were included in a prospective, multicenter cohort study. The study was designed to be as close to a population‐based study as possible, with centers participating only if they were able to include in their catchment area all children in whom JIA was diagnosed.

Results

Of 500 children included, 440 (88.0%) had repeated visits, with the last visit occurring at least 7 years after disease onset (median 98 months, range 84–147 months). Changes in the International League of Associations for Rheumatology category were observed in 10.8% of the children, and, in addition, extended oligoarthritis developed in 34.7% of the group with oligoarticular JIA. During the observation period, 58.0% of the children were treated with disease‐modifying antirheumatic drugs, including biologic medications. Ongoing disease activity was mostly mild, but some JIA‐related damage developed in 22.9% of the children. At the last followup visit, remission off medication was observed in 42.4% of the children, 8.9% were in remission on medication, and 48.7% were not in remission. The highest rates of remission were observed in patients with persistent oligoarticular JIA and in those with systemic JIA.

Conclusion

In this long‐term prospective study of JIA in a population‐based Nordic setting, ongoing disease was evident in a majority of the children. The present results underline the need to identify early predictors of outcome, to further improve therapy, and to continue long‐term followup of patients with JIA.

     

Inactivity‐associated medical costs among US adults with arthritis

Objective

To analyze direct medical costs among US adults with arthritis and estimate the proportion associated with inactivity.

Methods

In the 1987 National Medical Expenditure Survey, arthritis was defined using questions on self‐reported, doctor‐diagnosed arthritis or rheumatism. Physical activity was defined using a self‐report question on level of activity. Inactivity‐associated medical costs were derived by subtracting costs for active adults from costs for inactive adults after controlling for functional limitation.

Results

Among 5,486 adults with arthritis, inactive persons had higher medical costs than did active persons in all demographic groups examined. In multivariate models adjusting for key covariates, the proportion of costs associated with inactivity averaged 12.4% ($1,250 in 2000 dollars) and ranged from 7.8% to 14.3% among various demographic groups.

Conclusion

Inactivity‐associated medical costs among persons with arthritis are considerable. Physical activity interventions may be a cost‐effective strategy for reducing the burden of arthritis.

     

Physiologic response of the six‐minute walk test in children with juvenile idiopathic arthritis

Objective

To determine the physiologic response of the 6‐minute walk test (6‐mwt) in children with juvenile idiopathic arthritis (JIA).

Methods

Eighteen children with JIA (age 7–17 years; 6 boys, 12 girls) performed a 6‐mwt and a maximal exercise test.

Results

The physiologic response of the 6‐mwt was on average between 80% and 85% of the peak values of heart rate and oxygen uptake (VO _2peak) during the maximal exercise test, except for the minute ventilation, which had a mean percentage of 68.5%. Backward regression analysis showed that height and distance walked were the best predictors of VO _2peak during cycling (R² = 0.883, P < 0.001). During the 6‐mwt, the difference between the first and second minute was significant in every variable, except for heart rate. The range of walking distance of children with JIA was comparable with that of healthy elderly people.

Conclusion

The physiologic response of the 6‐mwt is at a submaximal, intense level of exercise. The course of the responses during the 6‐mwt was normal. The 6‐mwt can be regarded as a good test for measuring functional exercise capacity.

     

Cytokine gene polymorphisms and susceptibility to juvenile idiopathic arthritis

Objective

To investigate the involvement of candidate cytokine genes in the pathogenesis of juvenile idiopathic arthritis (JIA).

Methods

Single nucleotide polymorphisms and intragenic microsatellite markers within 8 candidate cytokine genes (interleukin‐1α [IL‐1α], IL‐2, IL‐4, IL‐6, IL‐10, interferon‐α1 [IFNA1], interferon‐γ [IFNG], and interferon regulatory factor 1 [IRF‐1]) were investigated in 417 Caucasian patients with clinically characterized JIA and a panel of 276 unrelated, healthy Caucasian controls, all from the United Kingdom.

Results

A novel 3′–untranslated region (3′UTR) polymorphism in IRF‐1 was found to be associated with susceptibility to JIA (corrected P = 0.002). No significant association with IL‐1α, IL‐2, IL‐4, IL‐6, IL‐10, IFNA1, or IFNG was observed.

Conclusion

An association between JIA and a previously unreported 3′UTR polymorphism of IRF‐1 was observed. This association was not found to be specific to any particular JIA subgroup. This suggests that IRF‐1 may contribute to a common pathogenesis shared by all JIA patients, regardless of clinical phenotype. This is most likely to be a genetic contribution to the chronic inflammatory process that underlies JIA pathology.

     

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.

     

Genetic loci contributing to hemophagocytic lymphohistiocytosis do not confer susceptibility to systemic‐onset juvenile idiopathic arthritis

Objective

To investigate whether single‐nucleotide polymorphisms (SNPs) within the genes PRF1, GZMB, UNC13D, and Rab27a, which are involved in natural killer cell dysfunction and known to contribute to the risk of hemophagocytic lymphohistiocytosis (HLH), confer an increased risk of susceptibility to systemic‐onset juvenile idiopathic arthritis (JIA).

Methods

Four SNPs across the PRF1 gene locus, 5 for GZMB, 7 for UNC13D, and 11 for Rab27a were investigated using MassArray genotyping in 133 UK Caucasian patients with systemic‐onset JIA and 384 ethnically matched unrelated control subjects. Additional control genotypes were accessed from the data generated by the Wellcome Trust Case Control Consortium.

Results

No significant association was found between any SNP within the 4 selected loci and systemic‐onset JIA, by either single‐point or haplotype analysis.

Conclusion

The results of this study demonstrate that genes involved in HLH do not confer a significant risk of association with systemic‐onset JIA.

     

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.

     

Long‐term outcome in patients with juvenile idiopathic arthritis

Objective

To describe the long‐term outcome of juvenile idiopathic arthritis (JIA).

Methods

All patients with JIA referred to a pediatric rheumatology center between 1978 and 1988 were identified and invited to undergo an assessment. Patients with JIA from a population‐based cohort from East Berlin were included. The outcome assessment considered changes in body function and structure (e.g., mortality, joint abnormalities, disease activity), activities at the individual level (Health Assessment Questionnaire), and participation in society (e.g., mobility, educational and vocational background).

Results

Of 260 eligible patients, 215 (83%) were evaluated. Subtypes of JIA at disease onset included oligoarthritis (40%), polyarthritis (14%), systemic arthritis (14%), psoriatic arthritis (1%), enthesitis‐related arthritis (15%), and other arthritis (16%). Followup was conducted after a median of 16.5 years. No deaths occurred in this cohort. At followup, approximately half of the patients had active disease and/or changes in body structures to a variable extent. Approximately one‐third of patients rated themselves as being functionally limited. Patients demonstrated good social integration: few mobility problems were reported, and the educational achievements of patients were higher and their rate of unemployment was lower compared with the age‐matched population. No significant differences in outcome were found between the population‐based and the referral‐based cohorts.

Conclusion

Even though approximately half of the JIA patients had more or less distinctive changes in body function and/or structure after a disease duration of >15 years, fewer than 10% were severely disabled or handicapped. Because JIA often persists into adulthood, long‐term followup and care are necessary.

     

Brief Report: Incidence of Selected Opportunistic Infections Among Children With Juvenile Idiopathic Arthritis

Objective

To compare incidence rates of selected opportunistic infections among children with and children without juvenile idiopathic arthritis (JIA).

Methods

Using US national Medicaid administrative claims data from 2000 through 2005, we identified a cohort of children with JIA based on physician diagnosis codes and dispensed medications. We also identified a non‐JIA comparator cohort of children diagnosed as having attention deficit hyperactivity disorder (ADHD). We defined 15 types of opportunistic infection using physician diagnosis or hospital discharge codes; criteria for 7 of these types also included evidence of treatment with specific antimicrobial agents. We calculated infection incidence rates. The rates in the ADHD comparator cohort were standardized to the age, sex, and race distribution of the JIA cohort. We calculated incidence rate ratios (IRRs) with 95% confidence intervals (95% CIs) to compare infection rates.

Results

The JIA cohort included 8,503 children with 13,990 person‐years of followup. The ADHD comparator cohort included 360,362 children with 477,050 person‐years of followup. When all opportunistic infections were considered together as a single outcome, there were 42 infections in the JIA cohort (incidence rate 300 per 100,000 person‐years; IRR 2.4 [95% CI 1.7–3.3] versus ADHD). The most common opportunistic infections among children with JIA were 3 cases of Coccidioides (incidence rate 21 per 100,000 person‐years; IRR 101 [95% CI 8.1–5,319] versus ADHD), 5 cases of Salmonella (incidence rate 35 per 100,000 person‐years; IRR 3.8 [95% CI 1.2–9.5]), and 32 cases of herpes zoster (incidence rate 225 per 100,000 person‐years; IRR 2.1 [95% CI 1.4–3.0]).

Conclusion

Opportunistic infections are rare among children with JIA. Nevertheless, children with JIA had a higher rate of opportunistic infections, including an increased rate of Coccidioides, Salmonella, and herpes zoster compared to children with ADHD.

     

The spontaneous remission of juvenile idiopathic arthritis is characterized by CD30+ T cells directed to human heat‐shock protein 60 capable of producing the regulatory cytokine interleukin‐10

Objective

To test the hypothesis that T cell reactivity to self heat‐shock protein 60 (Hsp60) in patients with remitting juvenile idiopathic arthritis (JIA) is part of an antiinflammatory, regulatory mechanism.

Methods

Using peripheral blood–derived mononuclear cells (PBMCs) and synovial fluid–derived mononuclear cells (SFMCs) obtained from patients with JIA, we analyzed the expression of CD30 and the induction of regulatory cytokines in response to human and mycobacterial Hsp60.

Results

In oligoarticular JIA patients, in vitro activation of PBMCs and SFMCs with Hsp60 induced a high expression of CD30 on CD4+, activated (HLA–DR–positive), memory (CD45RO+) T cells. The expression of CD30 induced by human Hsp60 was much higher than that induced by mycobacterial Hsp60. In oligoarticular JIA patients with active disease, the expression of CD30 in response to human Hsp60 was paralleled by a high interleukin‐10 (IL‐10):interferon‐γ (IFNγ) ratio. In addition, restimulated human Hsp60–specific T cell lines from oligoarticular JIA patients showed a high production of IL‐10 and a low production of IFNγ. In contrast, PBMCs and SFMCs from polyarticular JIA patients responded to human Hsp60 with virtually no expression of CD30 and a low IL‐10:IFNγ ratio.

Conclusion

The results show that T cells responding to human Hsp60 in oligoarticular JIA patients express CD30, and during active phases of the disease, these T cells have a cytokine profile with a high IL‐10:IFNγ ratio. These findings suggest that in oligoarticular JIA patients, human Hsp60–specific CD4+ cells have a regulatory function and contribute to disease remission.

     

Feasibility and construct validity of the parent willingness‐to‐pay technique for children with juvenile idiopathic arthritis

Objective

To assess the feasibility and construct validity of the willingness‐to‐pay (WTP) technique for measuring health care preferences in families of children with juvenile idiopathic arthritis (JIA).

Methods

Parents were asked to estimate the monthly US dollar amount they would be willing to pay to obtain for their child the following hypothetical drugs: ARTHRO, which guarantees complete clinical response; and NO‐STOM‐ACHE, a drug that eliminates gastrointestinal (GI) symptoms. A yes/no question was used with random assignment of the starting bids. Parents who agreed to pay the starting bid were then asked whether they would be willing to pay 200% and then 400% of this initial bid. Socioeconomic data and information on medications, disease activity, patient physical function, wellbeing, and health‐related quality of life (HRQOL) were obtained.

Results

Sixty‐two families of children with JIA were interviewed. GI symptoms were present in 54%, and 53% of the children had joints with active arthritis or limited range of motion. Four parents (7%) were unwilling to pay anything for any of the studied medications. The mean amount (median; mean percentage of available family income) families were willing to pay was $395 ($300; 15%) for ARTHRO and $109 ($80; 4%) for NO‐STOM‐ACHE. Correlation and regression analysis supported that, adjusted for the available family income, the WTP for ARTHRO was associated with disease activity, pain, and the HRQOL of the patients. After correction for the starting bids and the available family income, the WTP for NO‐STOM‐ACHE was associated with the patient's HRQOL, pain, and the amount of GI discomfort.

Conclusion

The WTP technique is feasible and has construct validity for measuring health care preferences for children with JIA. Relatively large WTP estimates support a possible important negative impact of the disease on families of children with JIA.

     

Effects of long‐term etanercept treatment on growth in children with selected categories of juvenile idiopathic arthritis

Objective

To evaluate the effects of long‐term etanercept treatment, with or without methotrexate, on growth in children with selected categories of juvenile idiopathic arthritis (JIA).

Methods

We conducted a 3‐year, open‐label, nonrandomized registry of 594 patients with polyarticular or systemic JIA treated with etanercept only, etanercept plus methotrexate, or methotrexate only. Height, weight, and body mass index (BMI) were assessed at baseline and at years 1, 2, and 3, using percentiles derived from US Centers for Disease Control and Prevention standardized growth charts.

Results

Statistically significant increases in the mean height percentiles from baseline were observed in etanercept‐treated patients at year 3 (4.8 percentile points) and in patients treated with etanercept plus methotrexate at years 1, 2, and 3 (2.4, 3.3, and 5.6 percentile points, respectively). Statistically significant increases from baseline in the mean weight percentiles were observed at years 1, 2, and 3 in both the etanercept group (7.4, 10.0, and 13.0 percentile points) and the etanercept‐plus‐methotrexate group (2.9, 6.9, and 8.4 percentile points, respectively). Statistically significant increases from baseline in the mean BMI percentiles were observed in both the etanercept group (range 9.6–13.8 percentile points) and the etanercept‐plus‐methotrexate group (range 2.1–5.2 percentile points). The mean height, weight, and BMI percentiles did not change significantly in patients in the methotrexate‐only group.

Conclusion

Etanercept treatment, with or without methotrexate, may contribute to the restoration of normal growth in children with JIA.

     

Sleep disturbances and neurobehavioral functioning in children with and without juvenile idiopathic arthritis

Objective

To compare sleep disturbances and neurobehavioral function in children with juvenile idiopathic arthritis (JIA) to age‐ and sex‐matched control children.

Methods

Children (n = 116) ages 6–11 years with (n = 70) and without (n = 46) JIA and their parents participated. Parents completed questionnaires on sleep habits, sleep behavior, and school competence of their children; children completed computerized neurobehavioral performance tests.

Results

Compared to control children, children with JIA had a statistically significant (P < 0.001) greater mean overall sleep disturbance score and higher scores on 6 of 8 subscales (all P < 0.03) of the Children's Sleep Habits Questionnaire (CSHQ). There were no group differences on neurobehavioral performance test scores. However, regardless of group, children with an overall CSHQ score above an established cutoff for clinically significant sleep disturbances had slower mean simple reaction time (t = ?2.2, P < 0.03) and mean 5‐choice reaction time (t = ?2.3, P < 0.02) compared to those below the cutoff score. The CHSQ overall sleep disturbance score predicted reaction time (P < 0.009) after controlling for age, intelligence quotient, medication, and group.

Conclusion

Children with JIA have more parent‐reported sleep disturbances, but performed as well as control children on a series of standardized computer tests of neurobehavioral performance. Children with more disturbed sleep had slower reaction times.

     

Aggrecanase cleavage in juvenile idiopathic arthritis patients is minimally detected in the aggrecan interglobular domain but robust at the aggrecan C‐terminus

Objective

To investigate aggrecan degradation in juvenile idiopathic arthritis (JIA).

Methods

The pattern and abundance of aggrecan fragments in synovial fluid (SF) aspirates from JIA patients were analyzed and compared with aggrecan fragments in SF from patients with other arthritides, children with knee injury, and a knee‐healthy reference group. Concentrations of sulfated glycosaminoglycan (sGAG) in SF were measured by Alcian blue precipitation assay. Aggrecan fragments were purified by dissociative CsCl density‐gradient centrifugation, deglycosylated, and analyzed by Western blot using antibodies specific for either aggrecanase‐derived ARGS, SELE, and KEEE neoepitopes or the aggrecan G3 domain.

Results

The concentration of sGAG in SF from patients with JIA was significantly lower compared with that in SF from patients with osteoarthritis (OA) (P < 0.001), patients with juvenile knee injury (P = 0.006), and knee‐healthy controls (P = 0.022). Western blot analysis revealed KEEE, SELE, and G3 fragments generated by aggrecanase cleavage in the chondroitin sulfate–rich region of aggrecan in patients with JIA. The pattern of aggrecan fragments in JIA patients was not identical to that in pooled OA SF, although there were notable similarities. Surprisingly, aggrecanase‐derived ARGS fragments were barely detectable in JIA SF, in marked contrast to levels in OA SF.

Conclusion

Aggrecanases appear to cleave minimally in the interglobular domain of aggrecan in JIA patients despite robust levels of cleavage in the chondroitin sulfate–rich region. These results suggest that in JIA, unlike other arthritides, aggrecanase cleavage in the aggrecan interglobular domain might not be a major pathogenic event.