Expression of myeloid‐related proteins 8 and 14 in systemic‐onset juvenile rheumatoid arthritis

Objective

To analyze which cellular compartments are involved in the initial phase of systemic‐onset juvenile rheumatoid arthritis (JRA), and to investigate the role that myeloid‐related protein 8 (MRP‐8) and MRP‐14, two S‐100 proteins that are primarily expressed in phagocytes, play in the disease.

Methods

Skin biopsy samples obtained during patients' acute episodes of systemic‐onset JRA were analyzed by immunohistochemistry and in situ hybridization. Concentrations of MRP‐8/MRP‐14 in serum were determined by enzyme‐linked immunosorbent assay.

Results

By analyzing biopsy samples from cutaneous rashes during the initial phase of systemic‐onset JRA, we discovered infiltration of leukocytes expressing MRP‐8 and MRP‐14. Surprisingly, keratinocytes also showed de novo synthesis of these proinflammatory proteins, indicating activation of epithelial cells during systemic‐onset JRA. Serum concentrations of MRP‐8/MRP‐14 were 120‐fold higher compared with healthy controls and ∼12‐fold higher compared with patients with other inflammatory diseases. Concentrations of MRP‐8/MRP‐14 in patients with systemic‐onset JRA fell dramatically after remission was induced.

Conclusion

The exceptionally high serum levels of MRP‐8 and MRP‐14 in active systemic‐onset JRA make them prime candidates as markers for monitoring disease activity and response to treatment. Since MRP‐8/MRP‐14 exhibit direct effects on leukocyte adhesion to the vascular endothelium, their extensive expression in the epidermis indicates an active role for these S‐100 proteins in the initial phase of this systemic autoimmune disease.

     

Increased perivascular synovial membrane expression of myeloid‐related proteins in psoriatic arthritis

Objective

To analyze S‐100 protein expression, in the form of myeloid‐related protein 8 (MRP8), MRP14, and the heterodimer MRP8/MRP14, in psoriatic arthritis (PsA) patients compared with rheumatoid arthritis (RA) and spondylarthropathy (SpA) patients, and to determine the effect of methotrexate (MTX) on the MRP antigen expression in PsA patients.

Methods

Serum, synovial fluid (SF), and synovium (taken at arthroscopy) samples were obtained from PsA (before and after MTX treatment), RA, and SpA patients. Concentrations of MRP8/MRP14 in serum and SF were measured by enzyme‐linked immunosorbent assay. Expression of MRP8, MRP14, and MRP8/MRP14 in synovium was determined by immunohistochemistry.

Results

MRP8, MRP14, and MRP8/MRP14 levels were increased in serum, SF, and synovium from PsA, RA, and SpA patients. In all 3 groups, paired samples of serum and SF showed significantly higher MRP8/MRP14 levels in SF (mean ± SD 15,310 ± 16,999 ng/ml [median 11,400]) than in serum (908 ± 679 ng/ml [median 695]) (P = 0.0001). MRP8/MRP14 levels in serum correlated with systemic parameters of disease activity (erythrocyte sedimentation rate [ESR] r = 0.55, P = 0.005; C‐reactive protein [CRP] level r = 0.55, P = 0.005), whereas levels in SF correlated with local parameters of disease activity (white blood cell count r = 0.45, P = 0.01; acute‐phase serum amyloid A level r = 0.32, P = 0.03). MRP expression was significantly higher in the synovial sublining layer (SLL) of PsA patients compared with RA and SpA patients. MRP antigens were predominantly expressed in perivascular areas of the SLL in PsA patients. Following MTX treatment, MRP expression in serum and synovium from PsA patients was significantly reduced. Serum levels of MRP were more sensitive to the effects of MTX than were the ESR, CRP, or clinical joint scores.

Conclusion

MRP levels in serum and SF correlate with local and systemic inflammation and are equally increased in PsA, RA, and SpA patients. In contrast, MRP8, MRP14, and MRP8/MRP14 expression in the SLL of PsA patients is increased, particularly in perivascular regions, compared with that in RA and SpA patients, suggesting a central role of MRP proteins in transendothelial migration of leukocytes in PsA. Moreover, MRP expression is reduced following MTX treatment. MRP proteins may represent a novel therapeutic target in inflammatory arthritis.

     

The diagnostic significance of soluble CD163 and soluble interleukin‐2 receptor α‐chain in macrophage activation syndrome and untreated new‐onset systemic juvenile idiopathic arthritis

Objective

Macrophage activation syndrome is characterized by an overwhelming inflammatory reaction driven by excessive expansion of T cells and hemophagocytic macrophages. Levels of soluble interleukin‐2 receptor α (sIL‐2Rα) and soluble CD163 (sCD163) may reflect the degree of activation and expansion of T cells and macrophages, respectively. This study was undertaken to assess the value of serum sIL‐2Rα and sCD163 in diagnosing acute macrophage activation syndrome complicating systemic juvenile idiopathic arthritis (JIA).

Methods

Enzyme‐linked immunosorbent assay was used to assess sIL‐2Rα and sCD163 levels in sera from 7 patients with acute macrophage activation syndrome complicating systemic JIA and 16 patients with untreated new‐onset systemic JIA. The results were correlated with clinical features of established macrophage activation syndrome, including ferritin levels.

Results

The median level of sIL‐2Rα in the patients with macrophage activation syndrome was 19,646 pg/ml (interquartile range [IQR] 18,128), compared with 3,787 pg/ml (IQR 3,762) in patients with systemic JIA (P = 0.003). Similarly, the median level of sCD163 in patients with macrophage activation syndrome was 23,000 ng/ml (IQR 14,191), compared with 5,480 ng/ml (IQR 2,635) in patients with systemic JIA (P = 0.017). In 5 of 16 patients with systemic JIA, serum levels of sIL‐2Rα or sCD163 were comparable with those in patients with acute macrophage activation syndrome. These patients had high inflammatory activity associated with a trend toward lower hemoglobin levels (P = 0.11), lower platelet counts, and significantly higher ferritin levels (P = 0.02). Two of these 5 patients developed overt macrophage activation syndrome several months later.

Conclusion

Levels of sIL‐2Rα and sCD163 are promising diagnostic markers for macrophage activation syndrome. They may also help identify patients with subclinical macrophage activation syndrome.

     

Defective phosphorylation of interleukin‐18 receptor β causes impaired natural killer cell function in systemic‐onset juvenile idiopathic arthritis

Objective

Systemic‐onset juvenile idiopathic arthritis (JIA) is an autoimmune disease characterized by arthritis and systemic features. Its pathogenesis is still largely unknown. It is characterized immunologically by natural killer (NK) cell dysfunction and cytokine signatures that predominantly feature interleukin‐1 (IL‐1), IL‐6, and IL‐18. Since IL‐18 can drive NK cell function, we examined how the high plasma levels of this cytokine are related to the documented NK cell failure in these patients.

Methods

The phenotype and function of NK cells from 10 healthy control subjects, 15 patients with polyarticular JIA, and 15 patients with systemic‐onset JIA were characterized by staining and functional assays in vitro. IL‐18 ligand binding was visualized by fluorescence microscopy. Phosphorylation of several MAP kinases and the IL‐18 receptor β (IL‐18Rβ) were visualized by Western blotting.

Results

IL‐18 from the plasma of systemic‐onset JIA patients stimulated the activation of NK cells from healthy controls and bound its cognate receptor. However, NK cells from systemic‐onset JIA patients failed to up‐regulate cell‐mediated killing molecules, such as perforin and interferon‐γ, after IL‐18 stimulation. Furthermore, treatment with IL‐18 did not induce the phosphorylation of receptor‐activated MAP kinases in NK cells. Alternate activation of NK cells by IL‐12 induced NK cell cytotoxicity. We observed no additive effect of IL‐18 in combination with IL‐12 in systemic‐onset JIA patients. Immunoprecipitation of IL‐18Rβ showed that NK cells from systemic‐onset JIA could not phosphorylate this receptor after IL‐18 stimulation.

Conclusion

The mechanism of the impaired NK cell function in systemic‐onset JIA involves a defect in IL‐18Rβ phosphorylation. This observation has major implications for the understanding and, ultimately, the treatment of systemic‐onset 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.

     

sE‐selectin for stratifying outcome in rheumatoid arthritis

Objectives

To determine the usefulness of sE‐selectin as a marker for early diagnosis and stratification of rheumatoid arthritis.

Methods

We investigated several markers of disease activity, including circulating adhesion molecules and other standard laboratory tests, in a 2–3 year followup analysis of patients with rheumatoid arthritis.

Results

The mean ± SD levels of sE‐selectin (91.68 ± 31.8 ng/ml versus 49.83 ± 14.76 ng/ml) and rheumatoid factor (375.7 ± 394.4 U versus 44.66 ± 37.63 U) were strongly elevated in severe (n = 15) versus mild (n = 7) courses of disease. Statistical calculation of mean and standard deviation revealed that sE‐selectin represents a highly significant marker for the presence of persistent and aggressive disease over time, regardless of therapeutic intervention and observation time points (P = 0.0004). Notably, regression analysis identified constant values for all parameters analyzed and, therefore, a stable course of the disease could be predicted from the beginning.

Conclusion

sE‐selectin appears to be a powerful marker to predict the severity of rheumatoid arthritis.

     

Subtype‐specific peripheral blood gene expression profiles in recent‐onset juvenile idiopathic arthritis

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.

     

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.

     

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.

     

Anakinra as first‐line disease‐modifying therapy in systemic juvenile idiopathic arthritis: Report of forty‐six patients from an international multicenter series

Objective

To examine the safety and efficacy of the interleukin‐1 (IL‐1) receptor antagonist anakinra as first‐line therapy for systemic juvenile idiopathic arthritis (JIA).

Methods

Patients with systemic JIA receiving anakinra as part of initial disease‐modifying antirheumatic drug (DMARD) therapy were identified from 11 centers in 4 countries. Medical records were abstracted using a standardized instrument, and resulting data were analyzed to characterize concomitant therapies, clinical course, adverse events, and predictors of outcome.

Results

Among 46 patients meeting inclusion criteria, anakinra monotherapy was used in 10 patients (22%), while 67% received corticosteroids and 33% received additional DMARDs. Outcomes were evaluated at a median followup interval of 14.5 months. Fever and rash resolved within 1 month in >95% of patients, while C‐reactive protein and ferritin normalized within this interval in >80% of patients. Active arthritis persisted at 1 month in 39% of patients, at 3 months in 27%, and at >6 months of followup in 11%. Approximately 60% of patients, including 8 of 10 receiving anakinra monotherapy, attained a complete response without escalation of therapy. Disease characteristics and treatment were similar in partial and complete responders, except that partial responders were markedly younger at onset (median age 5.2 years versus 10.2 years; P = 0.004). Associated adverse events included documented bacterial infection in 2 patients and hepatitis in 1 patient. Tachyphylaxis was not observed.

Conclusion

Anakinra as first‐line therapy for systemic JIA was associated with rapid resolution of systemic symptoms and prevention of refractory arthritis in almost 90% of patients during the interval examined. These results justify further study of IL‐1 inhibition as first‐line, rather than rescue, therapy in systemic JIA.

     

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.

     

Therapeutic efficacy of humanized recombinant anti–interleukin‐6 receptor antibody in children with systemic‐onset juvenile idiopathic arthritis

Objective

To investigate the safety and efficacy of a recombinant human anti–interleukin‐6 (anti–IL‐6) receptor monoclonal antibody (MRA) that indirectly inhibits the effects of IL‐6 in children with systemic‐onset juvenile idiopathic arthritis (JIA) refractory to high‐dose, long‐term corticosteroids.

Methods

An individual escalating‐dose trial was conducted in 11 children with active systemic‐onset JIA who met the inclusion criteria. All were first administered an intravenous dose of 2 mg/kg MRA. Each child without active inflammation was given a second identical dose 2 weeks later and a third identical dose 2 weeks after the second dose. Children with disease flares according to laboratory marker values received a 4‐mg/kg dose. Those without disease flares at this dose received a second 4‐mg/kg dose 2 weeks later and a third 4‐mg/kg dose 2 weeks after the second dose, while those with active inflammation received an additional 3 doses of 8 mg/kg MRA. Efficacy was evaluated every 2 weeks according to responses on the JIA core set of improvement criteria and the results of laboratory tests.

Results

MRA abruptly reduced disease activity in 10 of the 11 children, as assessed by the occurrence of febrile episodes, active arthritis, scores on the Childhood Health Assessment Questionnaire, and levels of acute‐phase reactants. However, levels of inflammatory reactants fluctuated until the proper MRA dose for each child was reached. Two weeks after the third fixed dose of MRA, 90.9% of all patients had a 30% improvement response, 90.9% had a 50% improvement response, and 63.6% had a 70% improvement response.

Conclusion

MRA treatment of children with active systemic disease results in clinical improvement and in normalized levels of acute‐phase reactants. MRA was safe and well tolerated and provided greater clinical benefit than conventional corticosteroids, considering the ill effects of IL‐6 and adverse events.

     

Lymphopenia is a risk factor in the progression of carotid intima‐media thickness in juvenile‐onset systemic lupus erythematosus

Objective

To characterize the atherosclerotic risk factors in the progression of subclinical atherosclerosis in patients with juvenile‐onset systemic lupus erythematosus (SLE).

Methods

This was a longitudinal study of 76 patients with juvenile‐onset SLE. Carotid arteries were evaluated using ultrasonography at baseline and at followup visits at 6‐month intervals over the 6‐year study period. Clinical and laboratory parameters, disease activity, treatment, and traditional risk factors for atherosclerosis were evaluated. Data were analyzed using generalized estimating equations.

Results

The mean ± SD age of the patients at baseline was 15.01 ± 3.48 years and the mean ± SD disease duration was 2.65 ± 2.5 years. The mean ± SD duration of followup was 3.74 ± 1.24 years. The mean ± SD intima‐media thickness (IMT) of the common carotid arteries differed significantly between the patient and control (n = 38) groups (0.63 ± 0.08 mm versus 0.54 ± 0.06 mm; P < 0.001). The presence of lymphopenia at diagnosis and at baseline and higher levels of serum creatinine and C‐reactive protein at baseline were positively associated with progression of carotid IMT (P = 0.006, P = 0.043, P = 0.037, and P = 0.049, respectively). In multivariate analysis, only lymphopenia at baseline and at diagnosis were consistently associated with progression of IMT (P = 0.012 and P = 0.045, respectively).

Conclusion

In patients with juvenile‐onset SLE, some nontraditional risk factors for the progression of subclinical atherosclerosis were identified. Lymphopenia was the only independent risk factor for the progression of IMT. The pathogenic mechanisms warrant further investigation.

     

Safety and efficacy of an oral histone deacetylase inhibitor in systemic‐onset juvenile idiopathic arthritis

Objective

The current treatment options for systemic‐onset juvenile idiopathic arthritis (JIA) are methotrexate, steroids, and biologic agents. This study was undertaken to evaluate the safety of the orally active histone deacetylase inhibitor givinostat (ITF2357) and its ability to affect the disease.

Methods

Givinostat was administered orally, for up to 12 weeks at a dosage of 1.5 mg/kg/day, to 17 patients with systemic‐onset JIA who had had active disease for ≥1 month. Disease activity was clinically assessed using the American College of Rheumatology Pediatric 30 (ACR Pedi 30), ACR Pedi 50, or ACR Pedi 70 criteria for improvement and a systemic feature score. The primary goal was safety and the primary efficacy end point was the number of patients completing 12 weeks of treatment who were responders.

Results

Givinostat was safe and well tolerated, with adverse events (AEs) being mild or moderate, of short duration, and self‐limited. The 17 patients from the intent‐to‐treat population reported a total of 44 AEs, and the 9 patients in the per‐protocol population reported a total of 25. Six AEs in 3 patients (nausea, vomiting, and fatigue) were related to the study drug, but each resolved spontaneously and no patient was withdrawn from the study due to drug‐related AEs. In the per‐protocol population at week 4, the improvement as measured by the ACR Pedi 30, ACR Pedi 50, and ACR Pedi 70, respectively, was 77.8%, 55.6%, and 22.2%, and this increased further to 77.8%, 77.8%, and 66.7% at week 12. The most consistent finding was the reduction in the number of joints with active disease or with limited range of motion.

Conclusion

After 12 weeks, givinostat exhibited significant therapeutic benefit in patients with systemic‐onset JIA, particularly with regard to the arthritic component of the disease, and showed an excellent safety profile.

     

The limited role of interferon‐γ in systemic juvenile idiopathic arthritis cannot be explained by cellular hyporesponsiveness

Objective

Systemic juvenile idiopathic arthritis (JIA) is an autoinflammatory syndrome in which the myelomonocytic lineage appears to play a pivotal role. Inflammatory macrophages are driven by interferon‐γ (IFNγ), but studies have failed to demonstrate an IFN‐ induced gene signature in active systemic JIA. This study sought to characterize the status of an IFN‐induced signature within affected tissue and to gauge the integrity of IFN signaling pathways within peripheral monocytes from patients with systemic JIA.

Methods

Synovial tissue from 12 patients with active systemic JIA and 9 with active extended oligoarticular JIA was assessed by real‐time polymerase chain reaction to quantify IFN‐induced chemokine gene expression. Peripheral monocytes from 3 patients with inactive systemic JIA receiving anti–interleukin‐1β (anti–IL‐1β) therapy, 5 patients with active systemic JIA, and 8 healthy controls were incubated with or without IFNγ to gauge changes in gene expression and to measure phosphorylated STAT‐1 (pSTAT‐1) levels.

Results

IFN‐induced chemokine gene expression in synovium was constrained in active systemic JIA compared to the known IFN‐mediated extended oligoarticular subtype. In unstimulated peripheral monocytes, IFN‐induced gene expression was similar between the groups, except that lower levels of STAT1, MIG, and PIAS were observed in patients with active disease, while higher levels of PIAS1 were observed in patients with inactive disease. Basal pSTAT‐1 levels in monocytes tended to be higher in systemic JIA patients compared to healthy controls, with the highest levels seen in those with inactive disease. Upon stimulation of monocytes, the fold increase in gene expression was roughly equal between groups, except for a greater increase in STAT1 in patients with inactive systemic JIA compared to controls, and a greater increase in IRF1 in those with active compared to inactive disease. Upon stimulation, the fold increase in pSTAT‐1 was highest in monocytes from patients with inactive systemic JIA.

Conclusion

Monocytes in patients with active systemic JIA retain the ability to respond to IFNγ, suggesting that the lack of an IFN‐induced gene signature in patients with active disease reflects a limited in vivo exposure to IFNγ. In patients with inactive systemic JIA who received treatment with anti–IL‐1β, hyperresponsiveness to IFNγ was observed.

     

Functional and prognostic relevance of the −173 polymorphism of the macrophage migration inhibitory factor gene in systemic‐onset juvenile idiopathic arthritis

Objective

To address the functional and prognostic relevance of the −173 single‐nucleotide G‐to‐C polymorphism of the macrophage migration inhibitory factor (MIF) gene in patients with systemic‐onset juvenile idiopathic arthritis (systemic‐onset JIA) by evaluating its association with serum and synovial fluid levels of MIF, with glucocorticoid requirement, and with the outcome of the disease.

Methods

A total of 136 patients with systemic‐onset JIA were studied, including 98 patients from the British Paediatric Rheumatology Study Group's National Repository for JIA and 38 patients who were followed up at the IRCCS Policlinico San Matteo (Pavia, Italy) and the IRCCS G. Gaslini (Genoa, Italy). The MIF‐173 polymorphism was genotyped using SnaPshot ddNTP primer extension and capillary electrophoresis. MIF levels were measured by enzyme‐linked immunosorbent assay. The evaluation of the association of the MIF‐173 polymorphism with outcome was performed only in Italian patients who were followed up for >5 years, by analyzing retrospectively 1) the number of joints with active arthritis and the number of joints with limited range of motion; 2) the score, at the last visit, on the Italian version of the Childhood Health Assessment Questionnaire (C‐HAQ); and 3) data concerning the treatment regimens during the disease course.

Results

Systemic‐onset JIA patients carrying a MIF‐173*C allele had serum and synovial fluid levels of MIF significantly higher than those in patients with the GG genotype. The duration of glucocorticoid treatment on a daily regimen was significantly longer in patients carrying a MIF‐173*C allele than in MIF‐173 GG homozygous patients. Moreover, the duration of clinical response to intraarticular injection of triamcinolone hexacetonide was significantly shorter in patients carrying a MIF‐173*C allele. At the last visit, the numbers of joints with active arthritis, the C‐HAQ scores, and the numbers of joints with limited range of motion were significantly higher in patients carrying the MIF‐173*C allele.

Conclusion

Our study shows the functional relevance of the MIF‐173 polymorphism and suggests that the MIF‐173*C allele is a predictor of poor outcome in systemic‐onset JIA.

     

Prevalence,risk factors,and outcome of uveitis in juvenile idiopathic arthritis: A long‐term followup study

Objective

To assess the prevalence, risk factors, and long‐term outcome of uveitis in patients with juvenile idiopathic arthritis (JIA).

Methods

An inception cohort of all 1,081 patients diagnosed as having JIA at a single tertiary care center was established. A questionnaire and followup telephone calls were used to confirm the diagnosis of uveitis. Ophthalmologists' records of patients with uveitis were collected. Kaplan‐Meier and Cox regression analyses were used to assess risk factors for developing uveitis and for complications of uveitis.

Results

After a mean followup time of 6.9 years, 142 of 1,081 patients (13.1%) had developed uveitis. Risk factors were young age at diagnosis, female sex, antinuclear antibody positivity, and the subtype of JIA. The relative contribution of these risk factors was different for the different subtypes of JIA. Until the end of the study, uveitis complications had developed in 53 of 142 patients with uveitis (37.3%; 4.9% of the total cohort). Only 16 of 175 involved eyes (9.1%) in 14 of 108 patients (13%; 1.3% of the total cohort) for whom ophthalmology reports were available had best corrected visual acuity less than 20/40 (mean followup time for uveitis of 6.3 years). Abnormal vision was associated with synechiae or cataract.

Conclusion

Risk factors for developing uveitis were different among subtypes of JIA. The long‐term outcome of JIA‐associated uveitis in our cohort was excellent despite the high rate of complications.

     

CCL17/thymus and activation–related chemokine in Churg‐Strauss syndrome

Objective

Churg‐Strauss syndrome (CSS) is a Th2‐mediated systemic vasculitis characterized by eosinophilic infiltration, blood eosinophilia, and high IgE levels. CCL17/thymus and activation–regulated chemokine (TARC) is a chemokine responsible for the recruitment of Th2 cells. This study was undertaken to explore a possible role of CCL17/TARC in CSS.

Methods

CCL17/TARC levels in serum from patients with active or inactive CSS, hypereosinophilic syndrome, systemic small‐vessel vasculitis other than CSS, other types of eosinophilia, and healthy controls were determined by enzyme‐linked immunosorbent assay. Biopsy samples of affected tissue from CSS patients were examined by immunohistochemical staining for Th2 infiltration and CCL17/TARC expression.

Results

Serum CCL17/TARC levels were significantly elevated in CSS patients with active disease (mean ± SEM 1,122.0 ± 422.7 pg/ml) compared with controls (220.6 ± 27.9 pg/ml) and patients with inactive disease (388.9 ± 72.6 pg/ml) (P < 0.001 and P < 0.05, respectively). These levels correlated with the clinical disease course of CSS and with absolute eosinophil counts as well as IgE levels. Infiltrating Th2 cells in active CSS lesions were evidenced by CD294 staining. CCL17/TARC in the affected tissue of CSS patients was readily identified by immunohistochemical analysis. Elevated CCL17/TARC levels were also noted in patients with hypereosinophilic syndrome (794.5 ± 294.8 pg/ml) and other disorders associated with eosinophilia (1,096.0 ± 345.3 pg/ml) (both P < 0.005 versus controls).

Conclusion

CCL17/TARC may contribute to CSS pathogenesis by recruitment of Th2 cells into affected tissue. Serum CCL17/TARC levels reflect disease activity, and further studies to validate its use as an activity marker in CSS are warranted.