Interleukin-6 in juvenile idiopathic arthritis

Abstract

Juvenile idiopathic arthritis (JIA) is a chronic childhood arthritis. Its pathogenesis is very complicated, with the involvement of not only immune cells but various types of parenchymal cells, and is affected by both genetic and environmental predispositions. The clinical spectrum from inflammation to related conditions is largely mediated by cytokines including interleukin (IL)-6. Fluctuations in IL-6 and its related molecules can modulate the pathogenesis and the clinical presentation positively or negatively. The recent clinical impact of IL-6 blockade on JIA has begun a therapeutic paradigm shift. This review describes the characteristics of JIA, mainly focused on IL-6 with the current therapeutic perspective.     

Phalangeal bone ultrasound is of limited value in patients with juvenile idiopathic arthritis

OBJECTIVE: In children with juvenile idiopathic arthritis (JIA), alterations of the skeletal system have been described. The aim of this cross-sectional study was to evaluate a phalangeal bone ultrasound device in the assessment of the skeletal status in children with active JIA. METHODS: In 49 children with oligoarticular, polyarticular or systemic JIA, the speed of an ultrasound signal (Ad-SOS) through the phalanges of the dominant hand was measured using the Igea 1200. RESULTS: Children in all subgroups were significantly smaller than those in the reference population, but there were no significant deficits in Ad-SOS. The finger width was reduced only in patients with polyarticular JIA. The Ad-SOS correlated highly with height, but no correlation between the finger width and Ad-SOS, and no correlation between the standard deviation scores of body height and Ad-SOS were seen. CONCLUSIONS: Phalangeal ultrasound is strongly dependent on body and therefore bone size, but other parameters of bone and soft tissues influence the measurements as well. It is not possible to differentiate as to which extent the various components of bone and soft tissue influence the measurement results. Ultrasound might therefore be of limited value in the assessment or screening of the skeletal system in children with JIA.     

Interleukin-6, soluble interleukin-2 receptor and soluble interleukin-6 receptor in the sera of patients with different histological patterns of rheumatoid synovitis

OBJECTIVE: The present study was conducted to investigate whether the serum levels of interleukin 6 (IL-6), soluble IL-2 receptor (sIL-2R) and sIL-6R are associated with the morphological appearance of rheumatoid arthritis (RA). METHODS: Using the ELISA technique we measured the IL-6, sIL-2R and sIL-6R concentrations in the serum of 34 patients with RA and 28 patients with osteoarthritis (OA). Histological analysis of synovial samples distinguished 2 types of rheumatoid synovitis. Twenty-one RA specimens presented diffuse infiltrates of mononuclear cells without any specific microanatomical organization. In remaining 13 samples the formation of lymphocytic follicles with germinal center-like structures was found. RESULTS: Serum levels of IL-6, sIL-2R and sIL-6R were elevated in patients with RA compared to the OA control group (p < 0.001, p < 0.001 and p < 0.05 respectively). Concentrations of IL-6 and sIL-2R were highest in the serum of RA patients with follicular synovitis in comparison to patients with diffuse synovitis (p < 0.001 and p < 0.01 respectively) and could distinguish RA patients with these two histological variants of the disease. Serum levels of IL-6 and sIL-2R correlated with markers of disease activity such as ESR and CRP levels. In addition, the clinical data suggest a more severe disease among RA patients with follicular synovitis. CONCLUSION: Distinct histological types of rheumatoid synovitis associated with unique serum concentrations of IL-6 and sIL-2R reflect levels of disease activity and confirm the concept of RA heterogeneity.     

The diagnostic significance of soluble CD163 and soluble interleukin-2 receptor alpha-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 alpha (sIL-2Ralpha) 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-2Ralpha and sCD163 in diagnosing acute macrophage activation syndrome complicating systemic juvenile idiopathic arthritis (JIA). METHODS: Enzyme-linked immunosorbent assay was used to assess sIL-2Ralpha 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-2Ralpha 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-2Ralpha 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-2Ralpha and sCD163 are promising diagnostic markers for macrophage activation syndrome. They may also help identify patients with subclinical macrophage activation syndrome.     

Lymphokines and soluble interleukin-2 receptors in juvenile chronic arthritis

Summary Serum levels of interleukin (IL)-2, interferon gamma (IFNg) and soluble IL-2 receptors (sIL-2R) were determined in sera from 34 patients with poly-or pauciarticular juvenile chronic arthritis (JCA) by use of enzyme-linked immunosorbent assays (ELISAs). Levels of sIL-2R were elevated in the group of patients compared with those of healthy children and correlated significantly with several parameters of clinical activity, including the functional capacity, joint score, visual-analogue score and erythrocyte sedimentation rate (ESR). Serum IL-2 levels were also elevated in the JCA patients, correlating with the patients functional capacity. Serum levels of IFNg were below the detection limit of the assay. Our data supported the notion that T-cell activation plays a role in the immunopathologic processes leading to clinical JCA.     

Interleukin-18 as a mediator of systemic juvenile idiopathic arthritis

The objective of this report is to explore the balance between serum and synovial fluid levels of interleukin (IL)-18 in children with juvenile idiopathic arthritis (JIA). Blood samples were obtained from 81 children with JIA and 18 control children. Synovial fluid samples were collected from 16 children with oligoarticular JIA. Concentrations of IL-18 were determined using commercial kit. Patients with systemic JIA had higher serum levels of IL-18 than patients with other forms of JIA or control children, both during the active (median, range: 6,240, 1,600–78,750 pg/ml) and inactive (1,615, 513–3,270 pg/ml) phase of disease [analysis of variance (ANOVA), P < 0.05). Levels of IL-18 in sera of children with oligoarticular JIA (255, 89–4,342 pg/ml) were similar to the respective synovial fluid levels (217, 89–1,245 pg/ml). Serum levels of IL-18 were proportional to the erythrocyte sedimentation rate and levels of C-reactive protein, but inversely proportional to the haemoglobin levels. IL-18 appears to be an important mediator of systemic JIA, while it seems of a lesser relevance in pathogenesis of other JIA forms. Therefore, inhibition of IL-18 might be a base for a successful biological therapy for systemic JIA.     

Polymorphisms of genes encoding interleukin-4 and its receptor in Iranian patients with juvenile idiopathic arthritis

As cytokines, including interleukin-4 (IL-4), seem to have a pivotal role in the pathogenesis of juvenile idiopathic arthritis (JIA), this study is aimed at investigating of association of polymorphisms in IL-4 and IL-4 receptor α (IL-4RA) genes with susceptibility to JIA. A case-control study was conducted on 53 patients with JIA and 139 healthy unrelated controls. Single nucleotide polymorphisms of IL-4 gene at positions -1098, -590, and -33, as well as IL-4RA gene at position +1902 were genotyped using polymerase chain reaction with sequence-specific primers method and compared between patients and healthy individuals. At the allelic level, C allele at IL-4 -33 was found to be more frequent in patients compared to control (P value <0.01). At the genotypic level, CC genotype at IL-4 -590 (P value <0.01), together with CC and TT genotypes at IL-4 -33 (P value <0.01), were significantly higher in patients with JIA, while TC genotypes at IL-4 -590 and -33 positions were found to be lower in case group (P value <0.01). At the haplotypic level, IL-4 (positions -1098, -509, -33) TTC, GCC, and TTT haplotypes were significantly lower than controls (P value <0.01, P value?=?0.03, and P value?=?0.04, respectively). Although, TCC haplotype at the same positions was found to be higher in patients (P value <0.01). Polymorphic site of +1902 IL-4RA gene did not differ between cases and controls. Polymorphisms in promoter region of IL-4 but not IL-4RA genes confer susceptibility to JIA and may predispose individuals to adaptive immune responses.     

Soluble interleukin-2 receptor in juvenile rheumatoid arthritis.

Juvenile rheumatoid arthritis (JRA) is a chronic, relapsing, inflammatory childhood disease characterized by arthritis and systemic inflammation. At present there is no rapid, efficient laboratory method of assessing disease activity and degree of immune activation. We measured serum soluble interleukin 2 receptor (sIL-2R) levels in 85 samples from 72 patients (22 samples from patients with systemic JRA, 34 from polyarticular patients, 29 from pauciarticular patients, of which 10 were HLA-B27 positive). The mean sIL-2R level from patients was 1565 U/ml, which is significantly elevated compared to control values of 594 U/ml (p less than or equal to 0.005). The highest levels were seen in patients with systemic JRA (mean value 2121 U/ml) while the lowest values were seen in HLA-B27 positive (+) patients (mean value 899 U/ml). Patients with clinically active disease had significantly elevated levels (mean value 1745 U/ml) compared to patients with inactive disease (mean value 846 U/ml, p less than or equal to 0.01). Highest levels were seen in patients with active systemic JRA (mean value 2419 U/ml) while patients with pauciarticular JRA and B27 + JRA had the lowest sIL-2R levels (1167 and 1045 U/ml, respectively). sIL-2R levels were elevated in all subgroups of clinically active patients compared to controls (p less than or equal to 0.0005). Three of the 4 patients with serial sIL-2R measurements showed falling values during the period of clinical remission. Using regression analysis and likelihood ratio tests, we found a significant correlation between sIL-2R levels and both disease activity and joint count (p less than or equal to 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Soluble interleukin-6 receptor in rheumatoid arthritis

To investigate the pathophysiologic role of soluble interleukin-6 receptor (sIL-6R) in patients with rheumatoid arthritis (RA), serum sIL-6R levels were measured in 15 RA patients and 15 healthy control subjects using a sandwich enzyme-linked immunosorbent assay. Correlation analysis was performed between sIL-6R levels and clinical variables such as joint score, Lansbury’s index, C-reactive protein and platelet counts. Levels of sIL-6R and IL-6 were also measured in paired samples of serum and synovial fluid obtained at the same time from nine RA patients. Serum sIL-6R levels in RA patients (153.9±56.9 ng/ml) were significantly higher than those of control subjects (115.1±19.1 ng/ml;P<0.05). However, sIL-6R levels did not correlate with any clinical characteristic of RA. sIL-6R was detectable in synovial fluid, but was invariably lower than in serum, in contrast to IL-6 (i.e. much higher in synovial fluid). It correlated neither with total cell nor neutrophil number in synovial fluid. Serum C-reactive protein levels were significantly correlated with IL-6 in synovial fluid, but not with sIL-6R in synovial fluid. These results indicate that serum sIL-6R levels are increased in RA patients. High levels of serum sIL-6R did not seem to be derived from the site of local inflammation. The readily detectable sIL-6R in synovial fluid may co-operate with IL-6 in the pathogenesis of synovitis in RA.     

Soluble interleukin-6 receptor in rheumatoid arthritis

Abstract

To investigate the pathophysiologic role of soluble interleukin-6 receptor (sIL-6R) in patients with rheumatoid arthritis (RA), serum sIL-6R levels were measured in 15 RA patients and 15 healthy control subjects using a sandwich enzyme-linked immunosorbent assay. Correlation analysis was performed between sIL-6R levels and clinical variables such as joint score, Lansbury’s index, C-reactive protein and platelet counts. Levels of sIL-6R and IL-6 were also measured in paired samples of serum and synovial fluid obtained at the same time from nine RA patients. Serum sIL-6R levels in RA patients (153.9±56.9 ng/ml) were significantly higher than those of control subjects (115.1±19.1 ng/ml; P<0.05). However, sIL-6R levels did not correlate with any clinical characteristic of RA. sIL-6R was detectable in synovial fluid, but was invariably lower than in serum, in contrast to IL-6 (i.e. much higher in synovial fluid). It correlated neither with total cell nor neutrophil number in synovial fluid. Serum C-reactive protein levels were significantly correlated with IL-6 in synovial fluid, but not with sIL-6R in synovial fluid. These results indicate that serum sIL-6R levels are increased in RA patients. High levels of serum sIL-6R did not seem to be derived from the site of local inflammation. The readily detectable sIL-6R in synovial fluid may co-operate with IL-6 in the pathogenesis of synovitis in RA.     

Effect of cyclosporin A on interleukin-6 and soluble interleukin-2 receptor in patients with rheumatoid arthritis.

OBJECTIVE--To investigate the effect of cyclosporin A (CyA) therapy on circulating concentrations of interleukin-6 (IL-6) and soluble interleukin-2 receptor (sIL-2R) in patients with rheumatoid arthritis (RA). METHODS--Twenty four RA patients with active disease were studied. Plasma was collected before and after 16 weeks of CyA treatment. IL-6 was measured by B9 bioassay and sIL-2R by enzyme linked immunosorbent assay (ELISA). RESULTS--The initial median IL-6 concentration of 165 IU/ml decreased significantly to 71 IU/ml after 16 weeks (p < 0.05). Similarly, the initial median plasma sIL-2R value of 665 U/ml decreased significantly to 570 U/ml (p < 0.05). This decrease was accompanied by an improvement in clinical parameters of disease activity. Some association between sIL-2R, IL-6, haemoglobin, and platelets was also observed. CONCLUSIONS--This study has demonstrated that, in vivo, CyA therapy in RA can significantly reduce circulating concentrations of IL-6 and sIL-2R. Modulation of both T and non-T cell derived cytokines may be one mechanism by which CyA improves rheumatoid disease. Whether this is a direct effect of CyA on the cells within the rheumatoid joint producing these cytokines or an indirect effect mediated by other cytokines which can influence IL-6 and Il-2R values remains to be determined.     

Synovial fluid and serum levels of soluble interleukin-6 receptor in patients with rheumatoid arthritis

Our objective was to measure both synovial fluid (SF) and serum levels of soluble interleukin-6 receptor (sIL-6R) in patients with rheumatoid arthritis (RA) and patients with osteoarthritis (OA), and to investigate the amounts of sIL-6R protein produced by cultured synovial cells, chondrocytes and mononuclear cells (MNCs). We measured levels of sIL-6R using a sensitive and specific enzyme-linked immunosorbent assay. Synovial cells, chondrocytes and MNCs were cultured, and the supernatants were also measured for sIL-6R. SF levels of sIL-6R in RA were significantly higher than those in OA. SF levels of sIL-6R significantly correlated with SF levels of IL-6 in RA. The serum level of sIL-6R was approximately 3-fold higher than the SF level of sIL-6R. sIL-6R protein was not detected in the supernatants of synovial cells and chondrocytes. As compared to the SF levels of sIL-6R, a small amount of sIL-6R protein was produced by SF MNCs. The above findings suggest that increased amounts of sIL-6R form IL-6-sIL-6R complexes which mediate IL-6 function in RA joints and that SF sIL-6R protein might be not only produced in affected joints, but also supplied from the serum.     

Synovial fluid and serum levels of soluble interleukin-6 receptor in patients with rheumatoid arthritis

Abstract

Our objective was to measure both synovial fluid (SF) and serum levels of soluble interleukin-6 receptor (sIL-6R) in patients with rheumatoid arthritis (RA) and patients with osteoarthritis (OA), and to investigate the amounts of sIL-6R protein produced by cultured synovial cells, chondrocytes and mononuclear cells (MNCs). We measured levels of sIL-6R using a sensitive and specific enzyme-linked immunosorbent assay. Synovial cells, chondrocytes and MNCs were cultured, and the supernatants were also measured for sIL-6R. SF levels of sIL-6R in RA were significantly higher than those in OA. SF levels of sIL-6R significantly correlated with SF levels of IL-6 in RA. The serum level of sIL-6R was approximately 3-fold higher than the SF level of sIL-6R. sIL-6R protein was not detected in the supernatants of synovial cells and chondrocytes. As compared to the SF levels of sIL-6R, a small amount of sIL-6R protein was produced by SF MNCs. The above findings suggest that increased amounts of sIL-6R form IL-6-sIL-6R complexes which mediate IL-6 function in RA joints and that SF sIL-6R protein might be not only produced in affected joints, but also supplied from the serum.     

Growth velocity and interleukin 6 concentrations in juvenile idiopathic arthritis

OBJECTIVE: .To evaluate associations of growth velocity with inflammatory markers and cumulative dose of glucocorticoid in a cohort of patients with juvenile idiopathic arthritis (JIA) followed during 1 year. METHODS: Seventy-nine patients were evaluated. Disease activity was evaluated by a pediatric rheumatologist. Anthropometric data were classified according to the World Health Organization standards. Tanner growth velocity curves were used; values below the Z-score < or = -2 were considered low growth velocity. Serum concentrations of interleukin 6 (IL-6) were measured by ELISA, and values > 1 pg/ml were considered elevated. RESULTS: The prevalence of low growth velocity was 25.3%, and it was associated with active disease on followup visit, elevated IL-6, erythrocyte sedimentation rate and C-reactive protein, and higher cumulative glucocorticoid doses. In the multiple linear regression with growth velocity as the dependent variable, only elevated IL-6 level was independently and negatively associated with growth velocity. CONCLUSION: Low growth velocity is highly prevalent in children with JIA. Elevated IL-6 levels seem to have an important negative influence on growth in these children, while total glucocorticoid exposure appears to be a secondary factor.     

Abnormal regulation of interleukin 6 in systemic juvenile idiopathic arthritis

OBJECTIVE: To evaluate the in vitro production of interleukin 6 (IL-6) by peripheral blood mononuclear cells (PBMC) of patients with systemic juvenile idiopathic arthritis (JIA), its regulation by IL-10, and the association of abnormal regulation of IL-6 production with presence of polymorphisms in the regulatory sequence of the IL-6 gene. METHODS: PBMC were cultured in the absence or presence of lipopolysaccharide (LPS). IL-6 and IL-10 levels were measured by ELISA. Polymorphisms in the regulatory sequences of the IL-6 gene were assessed by restriction fragment length polymorphism analysis and sequencing of amplified regions. RESULTS: Patients' PBMC produced high amounts of IL-6 compared to controls in unstimulated conditions. The IL-10 50% inhibitory dose of LPS stimulated IL-6 production was significantly higher in patients than controls. IL-10 levels produced in the absence or presence of LPS were comparable between patients and controls. The -174 G/C polymorphism in the IL-6 gene does not appear to be correlated with the high unstimulated IL-6 production or with the reduced inhibition by IL-10 observed in patients with JIA. No differences in patients compared to controls and with respect to the published sequence were found in the 3' untranslated region (UTR) of the IL-6 gene. CONCLUSION: Most patients with JIA have increased unstimulated production of IL-6 and reduced inhibition of IL-6 production by IL-10. This abnormal regulation of IL-6 production is not secondary to a defect in IL-10 production, and is not associated with polymorphism of alleles at position -174 of the 5' flanking region or with mutations in the 3' untranslated region of the IL-6 gene.     

Inflammation in juvenile idiopathic arthritis

Inflammation in JIA results from the interaction of myeloid, lymphoid, and stromal cells, cartilage destruction, bone erosion, and debility. These cells and the mediators they release cause cartilage destruction, bone erosion, and debility. Neutrophils are thought to mediate much of the actual destruction within a joint; however, many cases of JIA are not associated with boney erosions, but there is significant inflammation caused by the cellular infiltrate and the proliferation of synoviocytes. NSAIDs address many of the non-cell-dependent aspects of inflammation. Disease-modifying drugs are required for resistant or progressive disease. These agents are effective in modifying the cellular interactions that perpetuate inflammation. In particular, TNFalpha inhibitors impair cell migration into the joint and reduce macrophage functions.     

Higher frequency of allele 2 of the interleukin-1 receptor antagonist gene in patients with juvenile idiopathic arthritis

OBJECTIVE: An increased incidence of allele 2 of the interleukin-1 receptor antagonist gene (IL1RN*2) in several inflammatory diseases has recently been reported. The aim of this study was to examine a variable number tandem repeat (VNTR) polymorphism of the IL1RN gene in patients with juvenile idiopathic arthritis (JIA). METHODS: Findings in 185 Czech patients with JIA were compared with those in 168 Czech controls, 50 JIA patients and 52 controls of Turkish origin, and 79 controls from central England. VNTR polymorphism analysis of IL1RN was performed by polymerase chain reaction using 2 flanking primers to amplify an 86-bp tandem repeat region in intron 2. RESULTS: The frequency and carriage rate of IL1RN*2 were significantly increased in Czech JIA patients compared with the Czech controls (frequency 27.6% versus 15.8%; carriage rate 44.3% versus 26.2%). Increased frequency and carriage rate of IL1RN*2 were found in 23.3% and 40.0% of Turkish JIA patients and in 17.3% and 34.6% of ethnically matched controls. The high representation of IL1RN*2 in 52.3% of the 22 patients with extended oligoarthritis, 31.3% of the 56 patients with enthesitis-related arthritis, and 42.9% of the 14 patients with other arthritis was particularly responsible for the increased frequency of IL1RN*2 in the Czech JIA patients. We found no association of IL1RN*2 with disease activity or severity parameters. CONCLUSION: Inheritance of IL1RN*2 may contribute to genetic susceptibility in several forms of autoimmune diseases, including JIA. The IL1RN*2 allele may be useful as a prognostic indicator of the evolution of an extended oligoarticular course of JIA.     

Osteoporosis in juvenile idiopathic arthritis

Osteoporosis is characterized by loss of both bone mass and microarchitectural integrity, resulting in an increased risk of fractures with associated morbidity and mortality. Awareness of this condition is increasing in pediatrics, including pediatric rheumatology. Reduced bone mineral density is now well recognized in children and young adults with juvenile idiopathic arthritis and is multifactorial in origin. The problems of interpretation of bone analysis techniques during childhood and adolescence are highlighted. Recent studies have reported on the use of newer methods of imaging, including quantitative ultrasound and bone single photon emission computed tomography techniques. Attempting to disentangle the relative effects of disease activity, corticosteroids, nutrition, and physical activity in the development of osteoporosis in juvenile idiopathic arthritis is the focus of several studies. Finally, early optimistic reports of the use of bisphosphonates in juvenile idiopathic arthritis are welcome additions to the growing body of literature in this area.     

Autoantibodies in juvenile idiopathic arthritis: glucose-6-phosphate isomerase is not a specific target

OBJECTIVE: Antibodies recognizing the ubiquitous cytosolic enzyme glucose-6-phosphate isomerase (GPI) cause arthritis in the K/BxN mouse model. Studies have shown that these antibodies are not specific for rheumatoid arthritis (RA) in humans. We evaluated GPI as a target of autoantibodies in juvenile idiopathic arthritis (JIA). METHODS: We studied 324 serum and 48 synovial fluid (SF) samples from 103 patients with JIA, 36 with RA, and 8 with arthralgia and 11 controls. Anti-GPI antibodies were assessed by densitometrically evaluating immunoblots and ELISA using native and recombinant GPI. We determined the GPI activity of the soluble antigen in serum and SF. RESULTS: Although several samples contained anti-GPI-IgG antibodies, this was not specific for JIA or its subgroups, or for RA. Other proteins in the GPI preparation were also frequently recognized by antibodies. Additionally, we observed increased GPI activity in patients with the systemic manifestation of JIA, but not in other patients. Neither anti-GPI concentrations nor GPI activity were associated with disease activity. CONCLUSION: In addition to the findings in RA, our results indicate that GPI is not a general target of autoantibodies in JIA.