Rheumatoid factors and anticyclic citrullinated peptide antibodies in pediatric rheumatology

The effect of intra-articular steroid injection on the cartilage and tendon thicknesses in juvenile idiopathic arthritis

OBJECTIVES

Intra-articular corticosteroid injection (IACI) is a safe first-line or adjunct therapy used in any subtype of juvenile idiopathic arthritis (JIA). Limited studies evaluated the effect of IACI on cartilage. Our study aimed to examine the femoral cartilage thickness of patients with JIA who received IACI to the knee joint using ultrasound.

METHODS

We randomly selected JIA patients who performed IACI in the knee joint. Baseline bilateral joint cartilage and tendon thicknesses were measured. The articular fluid was aspirated, and applied IACI at the same period. Six months after injection, the exact measurements were repeated. Distal femoral cartilage, quadriceps tendon, and distal and proximal patellar tendon thicknesses were compared at the baseline (before IACI) and 6 months after IACI.

RESULTS

Thirty patients with JIA were included, and 23 (76.7%) were female. The median age was 11 years (interquartile range, 6 to 14), and the median disease duration was 3.3 years (interquartile range, 5 months to 5 years). The subtypes of JIA were oligoarticular in 25 (83.3%), polyarticular in 2 (6.7%), enthesitis-related arthritis in 2 (6.7%), and juvenile psoriatic arthritis in 1 (3.3%). Distal femoral cartilage thickness was 2.96 ± 0.79 mm at baseline and 2.85 ± 0.70 mm at 6 months after IACI (P = .35). The tendon thicknesses were similar at 6 months after baseline measurements.

CONCLUSIONS

Our findings reveal that knee IACI in patients with JIA did not significantly change cartilage and tendon thicknesses. This observation could indicate that IACIs have no detrimental effects on the cartilage and the tendons.

Clinical, Immunological and Inflammatory Characteristics among Mexican Children with Different Subtypes of Juvenile Idiopathic Arthritis: Exploring the Correlation between Anti-Cyclic Citrullinated Peptide (anti-CCP) and Rheumatoid Factor (RF)

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in childhood, affecting one to four of every 1000 children worldwide. It is characterized by joint inflammation lasting more than six weeks in children under 16 years. The aim of this study was to estimate the frequency of JIA subtypes in the Mexican patient population; compare clinical, immunological and inflammation markers by JIA subtype; and examine the correlation between these variables.

METHODS

We conducted a cross-sectional study of 50 patients with JIA (2-15 years). We estimated the frequency of each JIA subtype, assessed and compared the immunological characteristics (RF, ANA and anti-CCP) by JIA subtype at the time of diagnosis using Kruskal-Wallis or chi-square tests, and calculated Spearman correlation coefficients between the assessments.

RESULTS

Our analysis included 50 patients, 29 (58%) girls and 21 (42%) boys, aged at the time of diagnosis 10.56  ±  3.99 years. The frequencies of JIA subtypes were RF-seropositive polyarthritis (34%), RF-seronegative polyarthritis (28%), systemic arthritis (16%), oligoarthritis (14%) and arthritis-related enthesitis (8%). We found a significant association between sex and JIA subtype (p = 0.014). There was a significant difference in anti-CCP levels by JIA subtype (p < 0.001). We also detected positive correlations between RF and anti-CCP (r = 0.63, p < 0.001) and between age and anti-CCP (r = 0.29, p = 0.041).

CONCLUSIONS

Our study suggests that the frequency of the polyarticular subtypes of JIA is higher in Mexican children compared to other populations. Our findings highlight the importance of considering the presence of anti-CCP and RF as important criteria when deciding on treatment for JIA patients as elevated levels of these antibodies may indicate early forms of adult rheumatoid arthritis.

B Cells on the Stage of Inflammation in Juvenile Idiopathic Arthritis: Leading or Supporting Actors in Disease Pathogenesis?

Juvenile idiopathic arthritis (JIA) is a term that collectively refers to a group of chronic childhood arthritides, which together constitute the most common rheumatic condition in children. The International League of Associations for Rheumatology (ILAR) criteria define seven categories of JIA: oligoarticular, polyarticular rheumatoid factor (RF) negative (RF-), polyarticular RF positive (RF+), systemic, enthesitis-related arthritis, psoriatic arthritis, and undifferentiated arthritis. The ILAR classification includes persistent and extended oligoarthritis as subcategories of oligoarticular JIA, but not as distinct categories. JIA is characterized by a chronic inflammatory process affecting the synovia that begins before the age of 16 and persists at least 6 weeks. If not treated, JIA can cause significant disability and loss of quality of life. Treatment of JIA is adjusted according to the severity of the disease as combinations of non-steroidal anti-inflammatory drugs (NSAIDs), synthetic and/ or biological disease modifying anti-rheumatic drugs (DMARDs). Although the disease etiology is unknown, disturbances in innate and adaptive immune responses have been implicated in JIA development. B cells may have important roles in JIA pathogenesis through autoantibody production, antigen presentation, cytokine release and/ or T cell activation. The study of B cells has not been extensively explored in JIA, but evidence from the literature suggests that B cells might have indeed a relevant role in JIA pathophysiology. The detection of autoantibodies such as antinuclear antibodies (ANA), RF and anti-citrullinated protein antibodies (ACPA) in JIA patients supports a breakdown in B cell tolerance. Furthermore, alterations in B cell subpopulations have been documented in peripheral blood and synovial fluid from JIA patients. In fact, altered B cell homeostasis, B cell differentiation and B cell hyperactivity have been described in JIA. Of note, B cell depletion therapy with rituximab has been shown to be an effective and well-tolerated treatment in children with JIA, which further supports B cell intervention in disease development.

14-3-3η Protein as a Potential Biomarker in Juvenile Idiopathic Arthritis

The 14-3-3η (eta) protein was evaluated as a biomarker in a cohort of patients with juvenile idiopathic arthritis (JIA), as well as disease- and healthy-controls, to determine its potential clinical utility. In this case-control study, levels of 14-3-3η protein were evaluated in archival specimens from patients with JIA, systemic lupus erythematosus (SLE), and rheumatoid arthritis (RA), as well as healthy pediatric controls. Just over 200 patients were evaluated, using specimens banked between 1990 and 2011. Comparisons were made to complete blood cell count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), anti-cyclic citrullinated peptide (anti-CCP) antibodies, and anti-nuclear antibody (ANA) positivity. 14-3-3η at levels 0.2 ng/mL or higher was considered positive. Fisher's exact tests, odds ratios, 95% confidence intervals, and p-values were reported. 14-3-3η positivity was seen in all included JIA subtypes. The rate of positivity was the highest in RF-positive (pos) polyarticular JIA. In the disease and healthy controls, lower rates of positivity were observed. The frequency of 14-3-3η positivity among RF-positive and RF-negative (neg) polyarticular JIA patients, especially at values ≥0.5 ng/mL (associated with poor outcomes in adults), was also highest. Several JIA patients with 14-3-3η positivity developed RF and anti-CCP positivity later in their disease. Significant levels of 14-3-3η can be found in approximately 30% of RF-pos and RF-neg patients with polyarticular JIA. This protein may represent a new biomarker for polyarticular JIA, particularly RF-neg polyarticular JIA.

The Utility and Experience with Disease Biomarkers in Juvenile Onset Arthritis vs. Adult Onset Arthritis

Juvenile idiopathic arthritis (JIA) is the most common but extremely heterogeneous group of rheumatic diseases of childhood. There are no reliable, well-researched and published biomarkers for diagnosis or monitoring in juvenile idiopathic arthritis as there are for rheumatoid arthritis (RA) in adults. Biomarkers are not utilized in classifying JIA as they are in adult RA, making the JIA classifications less clinically effective and informative. The situation presents a lost opportunity for early aggressive therapy in JIA patients. Various researchers have used diverse biomarkers anecdotally in JIA and more systematically in RA patients and have drawn inferences on their utility from their experiences. The experience with biomarkers from RA patients cannot necessarily be extrapolated for JIA patients because they are dissimilar diseases. This article reconnoiters the comparative utility of various arthritis biomarkers in adult as well as in JIA patients. In contrast to RA, JIA is in itself a diverse group of arthritis with clinically overlapping subgroups with diverse etiology. The difference in the etiopathogenesis of arthritis subgroups demands identifying subgroup-specific biomarkers for diagnosis/monitoring and subgroup-specific therapies for management. The diagnostic/prognostic value of the individual biomarker could be different in different types of arthritis and in different types of hosts. Understanding the utility of individual biomarkers and careful selection of the assay are important to achieve the best disease outcomes.

Autoantibodies in the Pathogenesis, Diagnosis, and Prognosis of Juvenile Idiopathic Arthritis

Autoantibody production occurs in juvenile idiopathic arthritis (JIA) and numerous other autoimmune diseases. In some conditions, the autoantibodies are clearly pathogenic, whereas in others the roles are less defined. Here we review various autoantibodies associated with JIA, with a particular focus on antinuclear antibodies and antibodies recognizing citrullinated self-antigens. We explore potential mechanisms that lead to the development of autoantibodies and the use of autoantibody testing in diagnosis and prognosis. Finally, we compare and contrast JIA-associated autoantibodies with those found in adults with rheumatoid arthritis (RA).

PADI4 and the HLA-DRB1 shared epitope in juvenile idiopathic arthritis

OBJECTIVE

Both genetic and environmental factors are associated with susceptibility to juvenile idiopathic arthritis (JIA). Many studies have reported that both a 'shared epitope' (SE) encoded by several HLA-DRB1 alleles and the peptidyl arginine deiminase type 4 (PADI4) gene polymorphisms are associated with susceptibility to rheumatoid arthritis (RA). However, it is uncertain whether JIA and RA share the latter genetic risk factor. Therefore, here we investigated relationships between HLA-SE and PADI4 polymorphisms with clinical subtypes of JIA.

METHODS

JIA patients (39 oligoarthritis, 48 RF-positive polyarthritis, 19 RF-negative polyarthritis and 82 systemic) and 188 healthy controls were genotyped for HLA-DRB1 by PCR-sequence-specific oligonucleotide probe methodology. Three PADI4 gene single nucleotide polymorphisms (SNPs), rs2240340, rs2240337 and rs1748033, were genotyped using TaqMan SNP Genotyping Assays.

RESULTS

Frequencies of the HLA-SE were higher in RF-positive polyarticular JIA than in healthy controls. RF-positive polyarticular JIA was associated with HLA-SE (OR = 5.3, 95% CI = 2.5-11.9, pc < 0.001). No associations were found between clinical subtypes of JIA and PADI4 allele frequency. Nonetheless, rs2240337 in the PADI4 gene was significantly associated with anti-cyclic citrullinated peptide antibody (ACPA)-positivity in JIA. The A allele at rs2240337 was a significant risk factor for ACPA positivity in JIA (OR = 5.6, 95% CI = 1.71-23.7 pc = 0.03).

CONCLUSION

PADI4 gene polymorphism is associated with ACPA-positivity in JIA. The association of HLA-SE with RF-positive polyarticular JIA as well as RA is confirmed in Japanese. Thus, HLA-SE and PADI4 status both influence JIA clinical manifestations.

Anti-cyclic citrullinated peptide antibodies in children with Juvenile Idiopathic Arthritis

AIM

The purpose of present study was to access the prevalence of anti-cyclic citrullinated peptide (anti-CCP) antibodies in children with Juvenile Idiopathic Arthritis (JIA), and to investigate the clinical significance and diagnostic value of the anti-CCP antibodies in correlation with age, sex & activity.

METHODS

This case-control study was performed on 50 patients with JIA in addition to 40 sex and age-matched children as a control group. The participants were recruited from rheumatology Outpatient Clinic of Cairo University Specialized Pediatric Hospital. Patients were subjected to full history taking, clinical examination, routine laboratory investigations and x-rays on involved joints. Both patients and controls underwent assay of anti-CCP antibodies by AxSYM Anti-CCP IgG Microparticle Enzyme Immunoassay (MEIA) which is a semi-quantitative determination of the IgG class of autoantibodies specific to cyclic citrullinated peptide (CCP) in patients' serum or plasma. Data were analyzed using Mann-Whitney U test, ANOVA, and independent-samples t-test by SPSS version 15.

RESULTS

Anti-CCP positivity was identified amongst patients with JIA, particularly those JIA patients experiencing RF positive polyarticular disease onset. Above all, it is important that anti-CCP positivity and bone erosions, degree of joint damage, and ESR levels were significantly correlated.

CONCLUSION

Anti-CCP could be utilized as a valuable marker in the polyarticular form of JIA to direct early, and could be aggressive therapeutic intervention.

Autoantibodies and their Judicious Use in Pediatric Rheumatology Practice

Autoantibody testing forms an important part of diagnostic workup of patients in Pediatric rheumatology practice. However it is important to understand that the mere presence of autoantibodies does not necessarily mean the presence of an underlying autoimmune disease. Autoantibodies may be present decades before the development of clinical manifestations of an autoimmune disease and may be viewed as harbingers of Autoimmune disease. On the other hand, low-affinity autoantibodies may be present in normal healthy individuals; these natural autoantibodies serve an important function in immune regulation and tolerance. Autoantibody testing in pediatric practice mainly includes testing for anti-nuclear antibodies, anti-dsDNA antibodies, anti-neutrophil cytoplasmic autoantibodies and antiphospholipid antibodies. Rheumatoid factor and anti-CCP do not have much significance in the diagnostic schema in pediatric rheumatology, except perhaps for classification of juvenile idiopathic arthritis (JIA) and prognostication in late-onset polyarticular JIA. The positive predictive value (PPV) of any laboratory test depends on the prevalence of the disease in the population being tested. Hence, test ordering practices greatly impact the performance characteristics and positive predictive value of any laboratory test. A restricted test ordering only in patients with clinical signs and symptoms suggestive of autoimmune disease would thus greatly increase the PPV of tests such as antinuclear antibody used for diagnosing autoimmunity.

Laboratory Evaluation in Pediatric Autoimmune Diseases

Pediatric autoimmune diseases are chronic lifelong disorders associated with potential disability and increased morbidity and mortality if not properly recognized and treated. On the basis of largely expert opinion in addition to observational studies, children with suspected autoimmune disease should undergo general laboratory and autoantibody screening. (1)(2)(4)(6)(7)(11) There can be many causes of positive antinuclear antibody test results, including, but not limited to, autoimmune disease. On the basis of expert opinion and observational studies, a thorough history and physical examination as well as laboratory evaluation is recommended (often in consultation with a pediatric rheumatologist) to elucidate the cause for a positive test result. (4) (6)(11)

The child with joint pain in primary care

Joint pains are a common reason for children to present to primary care. The differential diagnosis is large including some diseases that do not primarily affect the musculoskeletal system. Although the cause for many patients will be benign and self-resolving, in rare cases the diagnosis is associated with long-term morbidity and mortality if not detected early and appropriately treated. These include primary and secondary malignancies, septic arthritis, osteomyelitis, inflammatory arthritis, slipped upper femoral epiphysis (SUFE) and non-accidental injury. We highlight the importance of a thorough history and directed yet comprehensive examination. A diagnostic algorithm is provided to direct primary care physicians' clinical assessment and investigation with the evidence base where available. In many cases, tests are not required, but if there is suspicion of malignancy, infection or inflammatory conditions, laboratory tests including full blood count, blood film, erythrocyte sedimentation rate, C-reactive protein and lactate dehydrogenase help to support or exclude the diagnosis. Autoimmune tests, such as antinuclear antibodies and rheumatoid factor, have no diagnostic role in juvenile idiopathic arthritis; therefore, we advise against any form of 'rheumatological/autoimmune disease screen' in primary care. Imaging does have a place in the diagnosis of joint pains in children, with plain radiographs being most appropriate for suspected fractures and SUFE, whilst ultrasound is better for the detection of inflammatory or infective effusions. The appropriate referral of children to paediatric rheumatologists, oncologists, orthopaedic surgeons and the emergency department are discussed.

Meta-analysis: diagnostic accuracy of anti-cyclic citrullinated peptide antibody for juvenile idiopathic arthritis

OBJECTIVE

To estimate the diagnostic accuracy of the anti-CCP test in JIA and to evaluate factors associated with higher accuracy.

METHODS

Two investigators performed an extensive search of the literature published between January 2000 and January 2014. The included articles were assessed by the Quality Assessment of Diagnostic Accuracy Studies tool. The meta-analysis was performed using a summary ROC (SROC) curve and a bivariate random-effect model to estimate sensitivity and specificity across studies.

RESULTS

The bivariate meta-analysis yielded a pooled sensitivity and specificity of 10% (95% confidence interval (CI): 6.0%-15.0%) and 99.0% (95% CI: 98.0%-100.0%). The area under the SROC curve was 0.96. Sensitivity estimates were highly heterogeneous, which was partially explained by the higher sensitivity in the rheumatoid factor-positive polyarthritis (RF+ PA) subtype (48.0%; 95% CI: 31.0%-65.0%) than in the other subtypes (17.0%; 95% CI: 14.0%-20.0%) and the higher sensitivity of the Inova assay (17.0%; 95% CI: 14.0%-20.%%) than the other assays (0.05%; 95% CI: 2.0%-11.0%).

CONCLUSIONS

Anti-CCP antibody test has a high specificity for the diagnosis of JIA. The sensitivity of this test is low and varies across populations but is higher in RF+ PA than in other JIA subtypes.

Anti-type II collagen antibodies, anti-CCP, IgA RF and IgM RF are associated with joint damage, assessed eight years after onset of juvenile idiopathic arthritis (JIA)

BACKGROUND

Early appearance of antibodies specific for native human type II collagen (anti-CII) characterizes an early inflammatory and destructive phenotype in adults with rheumatoid arthritis (RA). The objective of this study was to investigate the occurrence of anti-CII, IgM RF, IgA RF and anti-CCP in serum samples obtained early after diagnosis, and to relate the occurrence of autoantibodies to outcome after eight years of disease in children with juvenile idiopathic arthritis (JIA).

METHODS

The Nordic JIA database prospectively included JIA patients followed for eight years with data on remission and joint damage. From this database, serum samples collected from 192 patients, at a median of four months after disease onset, were analysed for IgG anti-CII, IgM RF, IgA RF and IgG anti-CCP. Joint damage was assessed based on Juvenile Arthritis Damage Index for Articular damage (JADI-A), a validated clinical instrument for joint damage.

RESULTS

Elevated serum levels of anti-CII occurred in 3.1%, IgM RF in 3.6%, IgA RF in 3.1% and anti-CCP in 2.6% of the patients. Occurrence of RF and anti-CCP did to some extent overlap, but rarely with anti-CII. The polyarticular and oligoarticular extended categories were overrepresented in patients with two or more autoantibodies. Anti-CII occurred in younger children, usually without overlap with the other autoantibodies and was associated with high levels of C-reactive protein (CRP) early in the disease course. All four autoantibodies were significantly associated with joint damage, but not with active disease at the eight-year follow up.

CONCLUSIONS

Anti-CII, anti-CCP, IgA RF and IgM RF detected early in the disease course predicted joint damage when assessed after eight years of disease. The role of anti-CII in JIA should be further studied.

Onset of polyarticular juvenile idiopathic arthritis with both anti-cyclic citrullinated peptide antibodies and rheumatoid factor in a 3-year-old girl

This report describes 3 year old girl with the unusual presentation of polyarticular juvenile idiopathic arthritis (JIA) with anti-cyclic citrullinated peptide (anti-CCP) antibodies and a positive rheumatoid factor (RF). She was initially treated with a nonsteroidal anti-inflammatory drug (NSAID; ibuprofen) followed by methotrexate (MTX, 10 mg/m2/week) and prednisolone (0.25 mg/kg/day), but these treatments were ineffective. Administration of tocilizumab, a humanized antihuman interleukin-6 receptor monoclonal antibody, promptly improved her clinical manifestations, and she has been in complete remission (DAS28 <2.6) without bone erosion and/or destruction. Positivity for both antibodies (anti-CCP and RF) can forecast the severity of JIA (radiographic bone destruction). In such cases the administration of biologic remissive therapy may be prudent early in the disease course.

Correlation analyses of clinical and molecular findings identify candidate biological pathways in systemic juvenile idiopathic arthritis

BACKGROUND

Clinicians have long appreciated the distinct phenotype of systemic juvenile idiopathic arthritis (SJIA) compared to polyarticular juvenile idiopathic arthritis (POLY). We hypothesized that gene expression profiles of peripheral blood mononuclear cells (PBMC) from children with each disease would reveal distinct biological pathways when analyzed for significant associations with elevations in two markers of JIA activity, erythrocyte sedimentation rate (ESR) and number of affected joints (joint count, JC).

METHODS

PBMC RNA from SJIA and POLY patients was profiled by kinetic PCR to analyze expression of 181 genes, selected for relevance to immune response pathways. Pearson correlation and Student's t-test analyses were performed to identify transcripts significantly associated with clinical parameters (ESR and JC) in SJIA or POLY samples. These transcripts were used to find related biological pathways.

RESULTS

Combining Pearson and t-test analyses, we found 91 ESR-related and 92 JC-related genes in SJIA. For POLY, 20 ESR-related and 0 JC-related genes were found. Using Ingenuity Systems Pathways Analysis, we identified SJIA ESR-related and JC-related pathways. The two sets of pathways are strongly correlated. In contrast, there is a weaker correlation between SJIA and POLY ESR-related pathways. Notably, distinct biological processes were found to correlate with JC in samples from the earlier systemic plus arthritic phase (SAF) of SJIA compared to samples from the later arthritis-predominant phase (AF). Within the SJIA SAF group, IL-10 expression was related to JC, whereas lack of IL-4 appeared to characterize the chronic arthritis (AF) subgroup.

CONCLUSIONS

The strong correlation between pathways implicated in elevations of both ESR and JC in SJIA argues that the systemic and arthritic components of the disease are related mechanistically. Inflammatory pathways in SJIA are distinct from those in POLY course JIA, consistent with differences in clinically appreciated target organs. The limited number of ESR-related SJIA genes that also are associated with elevations of ESR in POLY implies that the SJIA associations are specific for SJIA, at least to some degree. The distinct pathways associated with arthritis in early and late SJIA raise the possibility that different immunobiology underlies arthritis over the course of SJIA.

The role of anti-cyclic citrullinated peptide (CCP) antibodies in early detection of rheumatoid arthritis: an overview of the INOVA Diagnostics, Inc. QUANTA Lite CCP assays

INTRODUCTION

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and the presence of self-reactive autoantibodies. Since the discovery of anti-cyclic citrullinated peptide (anti-CCP) antibodies, several assays have been developed to measure these autoantibodies in RA patients. The first-generation kit offered high specificity, but sensitivity was low. The second-generation IgG anti-CCP antibody assay (CCP2) offered the same high specificity, with greatly improved sensitivity for RA. INOVA Diagnostics, Inc. offers, in addition to CCP2, a third-generation assay with higher sensitivity compared with CCP2 and also a combined IgG/IgA anti-CCP antibody assay.

AREAS COVERED

The review covers the use of INOVA Diagnostics, Inc. multiple anti-CCP antibody assays in early detection of RA, while also comparing these assays with other commercially available methods of measuring anti-CCP antibodies. While most of the review focuses on the significance of these autoantibodies in adult RA patients, their role in juvenile idiopathic arthritis is also discussed.

EXPERT OPINION

Detection of anti-CCP antibodies has emerged as one of the most important disease markers in RA patients. Several methods are available to measure anti-CCP antibodies, and isotyping and identification of citrullination targets are now the next step in further characterizing these autoantibodies.

Anti-cyclic citrullinated peptide (anti-CCP) antibody in juvenile idiopathic arthritis (JIA): correlations with disease activity and severity of joint damage (a multicenter trial)

OBJECTIVES

To determine the presence of anti-CCP antibodies in children with JIA and to correlate its levels with Juvenile Arthritis Disease Activity Score (JADAS) and Sharp/Van der Heijde Score.

METHODS

The study population comprised 54 cases, with 29 patients (53.7%) who had polyarticular onset, 19 (35.2%) had pauciarticular onset and six (11.1%) had systemic onset JIA. All patients were subjected to complete clinical examination, assessment of disease activity by JADAS-27 (ESR), and radiological damage by Sharp/Van der Heijde Score. Laboratory investigations included a complete blood count, ESR first hour, ANA, IgM Rheumatoid factor (RF) and serum anti-CCP2, and were used for further correlations.

RESULTS

RF was positive in 14 (25.9%) patients and anti-CCP antibodies were positive in 13 (24.1%) patients, 12 of whom had polyarticular onset. There were significant differences between groups relative to RF (F=8.577, P=0.001) and anti-CCP antibodies (F=4.845, P=0.012) being higher in JIA patients with polyarticular onset compared to other subsets of JIA patients. The mean total of the Sharp/Van der Heijde Score was significantly higher among polyarticular-JIA patients with positive anti-CCP antibodies compared to those negative for anti-CCP antibodies (P=0.05). Anti-CCP positively correlated with CRP (r=0.521, P<0.001) and Sharp/Van der Heijde Score (r=0.457, P<0.001).

CONCLUSION

Anti-CCP antibodies were prevalent among JIA patients with polyarticular patterns compared to other disease patterns. Anti-CCP positively and significantly correlated with Sharp's score and CRP levels. Given that anti-CCP may be influential in the choice of the best therapeutic strategy in JIA with polyarticular pattern of onset.

Anticitrullinated protein antibodies and radiological progression in juvenile idiopathic arthritis

OBJECTIVE

The aim of the study was to investigate whether determination of anticitrullinated protein antibodies (ACPA) provides predictive information on severity of disease course and joint destruction in children with juvenile idiopathic arthritis (JIA).

METHODS

Sera from 74 children with JIA were examined for ACPA using the ELISA test. To assess joint destruction, plain radiographs of both hands were scored twice according to the Steinbrocker scale: at the beginning of observation and after 8.9 to 15.2 months (median 11.5 months) of the followup. Correlations between ACPA serum levels and the disease characteristics (type of JIA onset, disease activity, disease duration, radiological status) were investigated.

RESULTS

Twenty-six out of 74 examined children with JIA (35.0%) were ACPA-positive [> 5 relative units (RU)/ml]. ACPA were present in all types of JIA onset, including 36.6% of children with early stage JIA (disease duration < 6 months). All of the IgM-rheumatoid factor (RF)-positive children with polyarticular type of JIA onset were simultaneously positive for ACPA. ACPA levels correlated positively with disease activity at the beginning of the study (rho = 0.7196; p < 0.0001) and after followup (rho = 0.2485; p = 0.0486). Disease duration did not significantly affect ACPA serum levels. ACPA levels correlated positively with radiological joint destruction in children with JIA, both at the beginning of the study (rho = 0.4599; p = 0.0004) and after the followup period (rho = 0.5523; p < 0.0001).

CONCLUSION

ACPA were superior to IgM-RF in diagnosing JIA and provided predictive information on severity of disease course and radiological outcome.

Evidence of fibrinogen as a target of citrullination in IgM rheumatoid factor-positive polyarticular juvenile idiopathic arthritis

BACKGROUND

Several studies have noted the significance of measuring anti-cyclic citrullinated peptide (CCP) antibodies in juvenile idiopathic arthritis (JIA) as an important indicator for destructive disease, as is the case in rheumatoid arthritis (RA). While the role of anti-CCP antibodies in RA and JIA has become better understood, the identity of the target proteins of this modification has remained elusive. In this study, we evaluated serum from patients with various subtypes of JIA to investigate the presence of anti-deiminated (citrullinated) fibrinogen and anti-citrullinated α-enolase antibodies, and their association with RF and anti-CCP antibody isotypes.

METHODS

Sera were obtained from 96 JIA patients, 19 systemic lupus erythematosus (SLE) patients, and 10 healthy children. All sera were measured for antibodies against citrullinated and native fibrinogen and α-enolase by an enzyme linked immunosorbent assay (ELISA). In addition, all sera were assayed for anti-CCP antibody isotypes and rheumatoid factor (RF) isotypes by ELISA. The relationship between anti-citrullinated fibrinogen and anti-α-enolase antibodies and disease activity and joint damage were also investigated. All results were correlated with clinical and laboratory parameters using Spearman's rho correlation coefficient. Multiple logistic regression analysis was utilized to identify which variables were associated with joint erosions and diagnosis of JIA.

RESULTS

Thirty-one JIA patients (32%) demonstrated reactivity to citrullinated fibrinogen and 9 (9%) to citrullinated α-enolase. Reactivity to citrullinated fibrinogen and α-enolase was predominantly found in IgM RF-positive polyarthritis patients. Fourteen JIA patients reacted with native α-enolase and a higher percentage of SLE patients reacted with citrullinated α-enolase when compared to JIA patients. Anti-citrullinated fibrinogen antibodies correlated with the presence of IgG anti-CCP antibodies and IgA and IgM RF. The presence of anti-citrullinated α-enolase antibodies correlated with IgA anti-CCP antibodies. IgG anti-CCP antibodies were significantly associated with joint damage and anti-citrullinated fibrinogen antibodies were strongly associated with JIA when compared to control groups. Anti-citrullinated fibrinogen antibodies demonstrated high sensitivity (81%) for IgM RF-positive polyarticular JIA. IgG anti-CCP antibodies had the highest specificity (95%) for JIA, with anti-citrullinated fibrinogen antibodies, IgA anti-CCP antibodies and IgA RF all following at 84%.

CONCLUSIONS

JIA patient sera exhibited strong reactivity to anti-citrullinated fibrinogen antibodies and demonstrated high sensitivity and specificity for JIA, primarily in IgM RF-positive polyarthritis patients. Fibrinogen is one of several protein targets for citrullination in JIA.

B-cell pathology in juvenile idiopathic arthritis

Juvenile Idiopathic Arthritis (JIA) is the most common cause of chronic arthritis in childhood and adolescents and encompasses a heterogeneous group of different diseases. Due to the promising results of B-cell depleting therapies in rheumatoid arthritis the role of B-cells in autoimmune diseases has to be discussed in a new context. Additionally, experiments in mouse models have shed new light on the antibody-independent role of B-cells in the development of autoimmune diseases. In this review we will discuss the importance of B-cells in the pathogenesis of JIA appraising the question for an immunological basis of B-cell targeted therapy in JIA.

Laboratory tests in the diagnosis and follow-up of pediatric rheumatic diseases: an update

OBJECTIVES

We reviewed the literature to evaluate the role of common laboratory tests and to examine the recent progress in the laboratory diagnosis of pediatric rheumatic diseases.

METHODS

We used the PubMed database (1950-2008) to search for the keywords "laboratory," "erythrocyte sedimentation rate" (ESR), "C-reactive protein" (CRP), "blood cytology," "procalcitonin" (PCT), "complement system," "ferritin," "antistreptolysin O titer" (ASO), "autoantibodies," "genetic studies," in conjunction with "rheumatic disease in children" and "pediatric autoimmune diseases." All relevant original and review articles in English were reviewed as well as textbooks of pediatric rheumatology.

RESULTS

Laboratory tests (ESR, CRP, blood cytology, complement system, ferritin, ASO titer) play an important role in confirming a diagnosis and in the follow-up of rheumatic diseases in the pediatric age group. The ESR is probably the most widely measured index of the acute phase response. Measurement of CRP is very useful in the rapid diagnosis of infection as a progressive increase can be shown in the first 48 hours. Also, the subsequent fall in serum CRP concentration on resolution of inflammation is useful for monitoring the efficacy of treatment. In chronic diseases, a combination of CRP and ESR may provide the most useful information. Cytopenia and different forms of anemia can be encountered in many rheumatic diseases: they can be related to disease activity or to therapeutic side effects. Determination of complement levels (C3 and/or C4) is useful in the follow-up of systemic lupus erythematosus (SLE) and membranoproliferative glomerulonephritis. Ferritin is a laboratory hallmark of primary and secondary hemophagocytic lymphohistiocytosis. ASO titer should be obtained to confirm a diagnosis of acute rheumatic fever; other important antibody markers of streptococcal infection include antihyaluronidase, antideoxyribonuclease B, and antistreptokinase antibodies. We also found that, in the pediatric age, the main indication for synovial fluid analysis is suspected joint infection. Antinuclear antibodies, anti-Smith antigen, and anti-double-stranded DNA antibodies are important in the diagnosis of SLE, are useful prognostic markers, and facilitate clinical and treatment follow-up. Anti-SSA/Ro and anti-SSB/La antibodies are associated with Sjögren's syndrome and congenital heart block, while the anti-U1 small nuclear ribonucleoprotein antibodies show high specificity for mixed connective tissue disease. Repetitive spontaneous abortions, thrombocytopenia, and many types of venous or arterial thrombosis are associated with antiphospholipid antibodies. The presence of cytoplasmic antineutrophil antibodies is essential in the diagnosis of Wegener granulomatosis. The discovery of underlying single causative gene defects led to the identification of several autoinflammatory diseases, a group of genetic disorders characterized by recurrent attacks of inflammation (hereditary periodic fever syndromes). These include familial Mediterranean fever due to mutations in the Mediterranean fever (MEFV) gene, hyperimmunoglobulinemia D syndrome due to mutations in the MK gene for mevalonate kinase, cryopyrinopathies such as Muckle-Wells syndrome or neonatal-onset multisystemic inflammatory disease (neonatal-onset multisystemic inflammatory disease or chronic infantile neurological cutaneous and articular (CINCA)) associated with cold-induced autoinflammatory syndrome 1 gene mutations, and tumor necrosis factor receptor-associated periodic syndrome due to mutation of TNF receptor I gene.

CONCLUSIONS

Laboratory investigations play an important role in the diagnosis and follow-up of inflammatory rheumatic diseases in children. A good history and a complete physical examination are the best screening tests. Routine laboratory tests are useful to confirm a suspected diagnosis, to assess disease activity, and to measure the response and toxicity to treatment. Only a few tests represent diagnostic criteria such as antinuclear antibodies and anti-double-stranded DNA in SLE or cytoplasmic antineutrophil cytoplasmic autoantibodies in Wegener's granulomatosis. Recent advances in molecular genetics have impacted diagnosis, pathogenesis, and treatment in genetic fever syndromes.