Antibodies to mutated citrullinated vimentin and antibodies to cyclic citrullinated peptides in juvenile idiopathic arthritis

A comprehensive overview of juvenile idiopathic arthritis: From pathophysiology to management

Rheumatoid Arthritis (RA) is a progressive autoimmune disease. It is among the most widespread chronic illnesses in children, with an annual incidence of 1.6 to 23 new instances per 100,000 adolescents. About 1 child in every 1000 develops Juvenile Idiopathic Arthritis (JIA) type of chronic arthritis. The cause of JIA is not well known but what known is that it involves inflammation of the synovium and destruction of tissues in joints which can cause early-onset of oligo articular JIA. It is challenging to diagnose the condition in some children who initially complain of pain and joint swelling as there is no blood test discovered that can confirm the diagnoses of JIA. As JIA patients are immunosuppressed due to the use of drugs, making them vulnerable to catch infections like COVID 19 which can lead to cardiovascular diseases having high rate of morbidity and mortality. The comorbidity like Diabetes has higher incidence in these patients resulting in synergistic effect on inflammation. Currently, the connection of genetics in JIA provides evidence that HLA Class I and II alleles have a role in the pathophysiology of various subtypes of JIA which includes inflammation in the axial skeletal. The primary objective of therapy in juvenile idiopathic arthritis is the suppression of clinical symptoms. The pharmacological approach includes use of medications like DMARDs, NSAIDs etc. and non-pharmacological approach includes physiotherapy, which helps in restoring normal joint function and herbs as adjuvants which has the benefit of no side effects.

Prevalence and significance of serum 14-3-3η in juvenile idiopathic arthritis

BACKGROUND

Prompt diagnosis of juvenile idiopathic arthritis (JIA) is important to avoid long term complications. Elevated serum 14-3-3η levels improve the diagnostic sensitivity of rheumatoid factor (RF) and cyclic citrullinated peptide (CCP) antibody in adult rheumatoid arthritis (RA), and have been associated with more severe phenotype. We investigated the prevalence and clinical significance of serum 14-3-3η in different types of JIA.

METHODS

JIA patients (n = 151) followed by the Pediatric Rheumatology Core at Children's Hospital of Los Angeles were categorized into 5 groups: polyarticular JIA RF+ (PJIA RF+; n = 39), PJIA RF- (n = 39), psoriatic arthritis (PsA; n = 19), enthesitis-related arthritis (ERA; n = 18), and oligoarticular JIA (OJIA [control group]; n = 36). RF, CCP antibody, and 14-3-3η were measured for all patients. 14-3-3η serum levels > 0.2 ng/mL were considered positive. Disease activity was assessed by the Juvenile Arthritis Disease Activity Score-71 (JADAS-71).

RESULTS

Elevated 14-3-3η levels were detected in 34/151 (23%) patients, and across all groups tested. Most patients with 14-3-3η had titers ≥4 times above the cutoff value. The majority (22, 65%) of 14-3-3η-positive patients were also positive for RF or CCP antibodies, 16 (47%) were positive for all 3, and 12 (35%) were single-positive for 14-3-3η. The highest prevalence of 14-3-3η was in PJIA RF+ patients (49%), followed by OJIA (22%). Positivity for 14-3-3η was not significantly associated with disease activity or age at diagnosis.

CONCLUSION

Serum 14-3-3η can be detected in all forms of JIA tested but appears to be most common in PJIA RF+. 14-3-3η does not appear to correlate with disease activity in JIA.

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).

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.

Evaluation of anti-citrullinated type II collagen and anti-citrullinated vimentin antibodies in patients with juvenile idiopathic arthritis

BACKGROUND

To determine the prevalence and significance of anti-citrullinated vimentin and anti-citrullinated type II collagen antibodies and elucidate their role in the disease process of juvenile idiopathic arthritis (JIA).

METHODS

Sera were obtained from 95 patients with various subtypes of JIA, 19 systemic lupus erythematosus (SLE) patients, and 10 healthy children. Antibodies were measured in the sera against citrullinated and native type II collagen and vimentin (vim1-16 and vim 59-74) by enzyme-linked immunosorbent assay. Samples were compared to anti-cyclic citrullinated peptide (anti-CCP) antibody and rheumatoid factor (RF) isotypes, and our previously measured anti-citrullinated fibrinogen and α-enolase antibodies on the same patient population, in addition to erythrocyte sedimentation rate and C-reactive protein. The relationship between the anti-citrullinated antibody profile and disease activity and joint damage were also investigated.

RESULTS

Twenty-three JIA patients (24%) demonstrated reactivity to anti-citrullinated type II collagen. Ten JIA patients (10.5%) demonstrated reactivity to anti-citrullinated vimentin 1-16 antibodies and 7 (7.4%) to anti-citrullinated vimentin 59-74 antibodies. One IgM RF-positive polyarticular patient was positive for all 5 of the citrullinated autoantibodies tested. Thirty-seven different subsets of patients were identified based on their anti-citrullinated autoantibody and RF isotype profile. No significant associations were noted with anti-citrullinated type II collagen and anti-citrullinated vimentin antibodies with joint damage or disease activity. Anti-citrullinated vimentin 59-74 antibodies demonstrated the highest overall specificity at 89.7%, with anti-citrullinated vimentin 1-16 and anti-citrullinated type II collagen antibodies at 86.2%.

CONCLUSION

This study demonstrates that antibodies to multiple citrullinated epitopes are present in the sera of patients with various subtypes of JIA. It also demonstrates the frequent occurrence of anti-citrullinated type II collagen and anti-citrullinated fibrinogen antibodies. The presence of autoantibodies to citrullinated antigens in JIA patients is highly diverse.

Profiling anti-cyclic citrullinated peptide antibodies in patients with juvenile idiopathic arthritis

BACKGROUND

Anti-citrullinated protein/peptide antibodies (ACPA), have high specificity for rheumatoid arthritis (RA). Some children with juvenile idiopathic arthritis (JIA), phenotypically resemble RA and test positive for rheumatoid factor (RF) a characteristic biomarker of RA. We investigated the prevalence of ACPA and its relationship to other serologic markers associated with RA in a well-characterized JIA cohort.

METHODS

Cases were 334 children with JIA, 30 of whom had RF + polyarticular JIA. Sera from all cases and 50 healthy pediatric controls were investigated by ELISA at a single time point for anti-cyclic citrullinated peptide (anti-CCP) IgG, RF IgM, IgA and IgG, anti-RA33 IgG, and antinuclear antibodies (ANA). Comparisons between cases and controls were made using Chi-square or Fisher exact tests and T-tests.

RESULTS

The prevalence of RF was 8% among controls, and 12% among cases (ns). The prevalence of ACPA was 2% in controls and 14.3% in cases (OR 8.2, p <0.01). Children who were ACPA-positive and RF-negative (n = 23) had a significantly earlier onset-age (4.6 years vs. 12.1 years, p <0.00001) and had fewer HLA-DRB1 shared epitope alleles than those positive for both RF and ACPA (n = 25). Prevalence of anti-RA33 was not different between cases and controls.

CONCLUSIONS

ACPAs are detectable in 14% of children with JIA. Children with positive ACPA but negative RF are frequent, and may define a distinct subset of children with JIA. ACPA testing should be included in the classification of JIA.

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.

Juvenile idiopathic arthritis: Diagnosis and differential diagnosis

Juvenile idiopathic arthritis (JIA) is comprised of a heterogeneous group of several disease subtypes that are characterized by the onset of arthritis before the age of 16 years and has symptoms lasting at least 6 weeks. The previous classification of JIA included seven different categories, whereas its current classification was compiled by the International League of the Association for Rheumatology, and replaced the previous terms of "juvenile chronic arthritis" and "juvenile rheumatoid arthritis," which were used in Europe or North America, respectively, with the single nomenclature of JIA. As mentioned above, JIA is defined as arthritis of unknown etiology that manifests itself before the age of 16 years and persists for at least 6 weeks, while excluding other known conditions. The clinical symptoms of JIA can be quite variable. Several symptoms that are characteristic of arthritis are not necessarily diagnostic of JIA and may have multiple etiologies that can be differentiated with careful examination of patient history. The disease may develop over days or sometimes weeks, thereby making the diagnosis difficult at the time of presentation. To make a clinical diagnosis of JIA, the first step is to exclude arthritis with known etiologies. Of note, late treatment due to excessive delay of diagnosis can cause severe damage to joints and other organs and impair skeletal maturation. Therefore, early detection of JIA is critical to ensure prompt treatment and to prevent long-term complications including the likelihood of disability in childhood.