Antibodies to mutated citrullinated vimentin and disease activity score in early arthritis: a cohort study

Clinical significance of anti-mutated citrullinated vimentin antibodies in rheumatoid arthritis patients

BACKGROUND

Anti-mutated citrullinated vimentin (MCV) antibodies have recently been recommended as a better arthritis diagnostic marker.

OBJECTIVES

To investigate the association between anti-MCV antibodies and the clinical, functional, and radiographic characteristics of rheumatoid arthritis (RA) patients.

METHODS

This case-control study was conducted on 40 RA patients and 40 healthy subjects. All patients were subjected to an assessment of disease using the 28-joint DAS (DAS28) and Clinical Disease Activity Index (CDAI), function by HAQ-DI, physical activity by International Physical Activity Questionnaire (IPAQ), fatigue by Functional Assessment of Chronic Illness Therapy (FACIT), serological tests as well as anti-MCV Abs measurement. A plain X-ray of both hands and wrists was done.

RESULTS

The anti-MCV Abs level was significantly higher in RA patients than in healthy controls (P< 0.001). The anti-MCV Abs had a significant positive correlation with DAS, CDAI, HAQ, RF, Anti-CCP, and CRP (P= 0.006, 0.013, 0.005, < 0.001, < 0.001and 0.041 respectively) and a significant negative correlation with FACIT (p= 0.007). Positive anti-MCV RA patients had significantly higher erosions, JSN, and a total sharp score.

CONCLUSIONS

Anti-MCV Abs may contribute to poor physical activity and more fatigue in RA patients beyond their established role in disease activity and erosion.

Evaluation of autoantibodies against vimentin and α-enolase in rheumatoid arthritis patients

Introduction

Rheumatoid arthritis (RA) is categorized as an autoimmune disease with a frequency of 0.2–1% worldwide. It is reported that various autoantibodies are produced in the RA population, particularly against citrullinated peptides. Among various candidate markers for RA diagnosis, the citrullinated proteins have the highest specificity and sensitivity for both diagnosis and prognosis of RA. Anti-mutated citrullinated vimentin and α-enolase constitute a new class of autoantibodies for early detection of RA.

Material and methods

45 serum samples and 19 synovial fluid (SF) specimens collected from RA patients were considered for American College of Rheumatology criteria and 20 serum samples and 10 SF specimens were provided from healthy subjects as a control group. To assess the quantity of anti-citrullinated protein antibodies (ACPA), anti-mutated citrullinated vimentin (MCV) and anti-α-enolase in the serum and SF of RA patients were determined by the enzyme-linked immunosorbent assay (ELISA) method. For the evaluation of disease activity and joint destruction, we used the Disease Activity Score of 28 joints based on erythrocyte sedimentation rate (ESR) Disease Activity Score 28 (DAS28). Furthermore, to measure the molecular weight of vimentin and α-enolase, electrophoresis on 10% SDS-PAGE was performed as described before.

Results

The anti-α-enolase level among serum samples from RA patients was significantly higher than in healthy subjects (4.49 ±0.20 ng/ml vs. 0.76 ±0.12 ng/ml) (p < 0.001). There was a direct relation between α-enolase quantity and (rheumatoid factor) RF and C-reactive protein (CRP) levels. The mean ESR value in positive and negative ACPA patients was 38.2 ±22.6 mm/h and 9.2 ±5.8 mm/h respectively (p < 0.0001). The mean DAS28-ESR was 3.3. The level of anti-MCV in the serum of RA patients (244.6 ±53.3 U/ml) was higher than in serum of the healthy group (148.73 ±71.8) (p < 0.0001). The level of anti-MCV in the SF of patients was 687.5 ±148.4 U/ml.

Conclusions

In conclusion, both autoantibodies against MCV and α-enolase are two important markers that increase in serum and SF of RA patients and are specific for diagnosis of RA disease.

Increased primary care use for musculoskeletal symptoms, infections and comorbidities in the years before the diagnosis of inflammatory arthritis

Objectives

Little is known about relevant events in the at-risk phase of rheumatoid arthritis before the development of clinically apparent inflammatory arthritis (IA). The present study assessed musculoskeletal symptoms, infections and comorbidity in future IA patients.

Methods

In a nested case–control study using electronic health records of general practitioners, the frequency and timing of 192 symptoms or diseases were evaluated before a diagnosis of IA, using the International Classification of Primary Care coding system. Cases were 2314 adults with a new diagnosis IA between 2012 and 2016; controls were matched 1:2. The frequency of primary care visits was compared using logistic regression.

Results

The frequency of visits for musculoskeletal symptoms (mostly of shoulders, wrists, fingers and knees) and carpal tunnel syndrome was significantly higher in IA patients vs controls within the final 1.5 years before diagnosis, with ORs of 3.2 (95% CI 2.8 to 3.5), 2.8 (95% CI 2.5 to 3.1) and 2.5 (95% CI 2.2 to 2.8) at 6, 12 and 18 months before diagnosis, respectively. Also, infections (notably of the genital and urinary tracts), IA-comorbidities and chronic diseases were more prevalent in cases than controls, but more evenly spread out over the whole 6-year period before IA. A decision tree was created including all symptoms and diseases.

Conclusion

There was an increased frequency of primary care visits for musculoskeletal symptoms, infections and comorbidities prior to the diagnosis of IA. This diverging trend is present for 4–6 years, but becomes statistically significant 1.5 years before the diagnosis. Validation of these results is warranted.

Insights of rheumatoid arthritis risk factors and associations

Rheumatoid arthritis (RA) is a defective post-translational modification of citrullinated peptides which cause synovial inflammation in joints. The present review elaborates the basic mechanisms of RA and the root causes of molecular mechanisms. The gender-based differentiation and probabilitiesof RA causes were discussed. Many report studies supporting that females are more prone to RA than males maybe suspected that circulating estrogen hormones 16a-hydroxy estrone, 2-hydroxy estrogens involvement in the RA pathogenicity. Other important aspects like environmental factors and air pollutants like (SO2 and NO2) were also impacted and enhances the risk of RA were discussed. The root cause of pathomechanisms of peptidylarginine deiminase (PAD) enzymes in RA and autoimmunity factors were poorly understood, however, Ati-citrullinated peptides (ACP) are the powerful markers to diagnose the RA disease. This review discusses three main risk factors of RA to understand the RA pathogenesis and disease-modifying mechanisms, may provide a unique opportunity to determine disease prevalence and RA associations.

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Rheumatoid arthritis(RA) is caused by the defected peptides, environmental factor’s and hormonal dysregulation in synovial inflammation.

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The immune system attacks joint tissue for pathogenic citrullinated peptides causing inflammation in synovium, leading to RA.

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Risk factors, disorder proteins, cellular changes influence immune system to turns to self antigens leads to RA.

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Understanding the exact role and action of risk factors in RA is especially important given the prevention measures to RA are desirable.

Identification of a novel autoantibody against self-vimentin specific in secondary Sjögren's syndrome

Background

Sjögren’s syndrome (SS) is a primary autoimmune disease (pSS) or secondarily associated with other autoimmune diseases (sSS). The mechanisms underlying immune dysregulation in this syndrome remain unknown, and clinically it is difficult to diagnose owing to a lack of specific biomarkers.

Methods

We extracted immunoglobulins (Igs) from the sera of patients with sSS associated with rheumatoid arthritis (RA) and used them to screen a phage display library of peptides with random sequences.

Results

Our results show that an sSS-specific peptide, designated 3S-P, was recognized by sera of 68.2% (60 of 88) patients with sSS, 66.2% of patients with RA-sSS, and 76.5% of patients with systemic lupus erythematosus (SLE)-sSS. The anti-3S-P antibody was scarcely found in patients with pSS (1.8%), RA (1.3%), SLE (4.2%), ankylosing spondylitis (0%), and gout (3.3%), as well as in healthy donors (2%). The 3S-P-binding Igs (antibodies) were used to identify antigens from salivary glands and synovial tissues from patients with sSS. A putative target autoantigen expressed in the synovium and salivary gland recognized by anti-3S-P antibody was identified as self-vimentin.

Conclusions

This novel autoantibody is highly specific in the diagnosis of sSS, and the underlying molecular mechanism of the disease might be epitope spreading involved with vimentin.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1508-5) contains supplementary material, which is available to authorized users.

Diagnosis, prognosis and classification of early arthritis: results of a systematic review informing the 2016 update of the EULAR recommendations for the management of early arthritis

OBJECTIVE

To update the evidence pertaining to the diagnosis, prognosis and classification of patients with early arthritis (EA), and to inform the 2016 European League Against Rheumatism (EULAR) recommendations for the management of patients with EA.

METHODS

MEDLINE, EMBASE and Cochrane databases were searched up to October 2015. The first part of the systematic literature review (SLR) involved a search for studies investigating the recognition and referral of EA. The second part involved a search for studies to identify the place of laboratory and imaging tests in establishing a diagnosis and a prognosis in patients with EA.

RESULTS

Regarding the issue of referral of patients with EA (1643 hits), 4 studies were included. These studies were in support of early referral for patients with EA. Regarding the issue of diagnosis and prognosis of patients with EA (11 435 hits), 88 studies were included, evaluating mainly the value of rheumatoid factor (RF) and anticitrullinated-peptide antibodies (ACPAs). Sensitivity of these antibodies for a RA diagnosis in patients with EA was moderate (40-80%). Specificity was higher, notably for ACPAs (frequently >80%). ACPAs also showed better prognostic performance than RF (negative predictive values around 80%). We confirmed that structural damage on baseline X-rays is predictive of further radiographic progression in patients with EA. Regarding other imaging modalities, data are sparse.

CONCLUSIONS

This SLR highlights the importance of early referral for patients with EA and confirms that RF and mainly ACPAs as well as a search for structural X-rays changes may help in the diagnosis and prognosis of patients with EA.

Diagnostic accuracy of anti-MCV and anti-CCP antibodies in rheumatoid arthritis: A meta-analysis

OBJECTIVE

The purpose of this study was to compare the diagnostic performance of anti-mutated citrullinated vimentin (anti-MCV) and anti-cyclic citrullinated peptide (anti-CCP) antibodies in rheumatoid arthritis (RA).

METHODS

We searched the Medline, Embase, and Cochrane library databases and performed two meta-analyses on the diagnostic accuracy of anti-MCV and anti-CCP in patients with RA compared to healthy controls.

RESULTS

We identified 12 studies that included a total of 2003 RA patients and 831 healthy controls for the meta-analysis. The pooled sensitivity and specificity of anti-MCV were 68.6% [95% confidence interval (CI) 66.6-79.7] and 94.2% (95% CI 92.4-96.7) and those of anti-CCP were 61.7% (95% CI 59.5-63.8) and 97.1% (95% CI 96.7-98.1), respectively. Anti-MCV PLR, NLR, and DOR were 12.99 (95% CI 8.013-21.27), 0.297 (95% CI 0.238-0.369), and 47.78 (95% CI 28.59-79.84), and those for anti-CCP were 16.71 (95% CI 11.42-24.47), 0.378 (95% CI 0.325-0.439), and 54.20 (95% CI 31.65-92.82), respectively. The AUC of anti-MCV was 0.886, and its Q* index was 0.817, indicating modest accuracy, while the AUC of anti-CCP was 0.946, and its Q* index was 0.885. The sensitivity of anti-MCV was significantly higher than that of anti-CCP in the diagnosis of RA (difference 0.069, 95% CI 0.039-0.098, p < 0.0001), but the specificity of anti-MCV was lower than that of anti-CCP (difference -0.029, 95% CI -0.051 to -0.006, p = 0.012). The Q* index of anti-MCV was significantly lower than that of anti-CCP (difference -0.068, 95% CI -0.070 to -0.065, p < 0.0001).

CONCLUSION

Our meta-analysis demonstrates that anti-MCV is more sensitive but less specific, and has lower diagnostic accuracy than anti-CCP in RA, although anti-MCV and anti-CCP showed comparable high PLRs.

New autoantibodies associated with rheumatoid arthritis recognize posttranslationally modified self-proteins

Citrullination, carbamylation and oxidation are posttranslational modifications of proteins that produce neoepitopes. Rheumatoid arthritis (RA) is an autoimmune disease of which one distinctive feature is the development of B-cell-mediated immunity against these neoepitopes. Antibodies to citrullinated proteins (ACPAs) were identified nearly two decades ago and are now widely used in clinical practice. The identification of additional citrullinated proteins as potential autoantibody targets has suggested new pathophysiological hypotheses and prompted studies of potential associations with disease severity or specific disease patterns. Carbamylation is a nonenzymatic posttranslational modification that produces homocitrullines, against which newly identified autoantibodies different from ACPAs have been found in over 15% of patients with RA. Finally, the development of antibodies to oxidized type II collagen reflects immunization against collagen modified by oxidation in relation to intraarticular oxidative stress. These new autoantibodies are both sensitive and specific and may therefore serve as early disease markers and as useful tools for therapeutic monitoring.

Comparative analysis of autoantibodies targeting peptidylarginine deiminase type 4, mutated citrullinated vimentin and cyclic citrullinated peptides in rheumatoid arthritis: associations with cytokine profiles, clinical and genetic features

Antibodies against cyclic citrullinated peptides (anti-CCP) are widely used for diagnosis of rheumatoid arthritis (RA). We performed a comparative analysis of antibodies targeting the citrullinating enzyme peptidylarginine deiminase type 4 (anti-PAD4) and mutated citrullinated vimentin (anti-MCV) with anti-CCP autoantibodies in RA patients and examined their relationships with clinical parameters, cytokine profiles and the PADI4 gene. Autoantibodies were examined by enzyme-linked immunosorbent assay (ELISA) in sera of 170 RA patients and 103 controls. Cytokine profiles were measured using a multiplex system. PADI4 polymorphisms (89 G > A, 90 T > C and 92 G > C) were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Anti-PAD4, anti-MCV and anti-CCP autoantibodies were detected in 24, 61 and 74% of RA patients, respectively. Positive correlations were observed between anti-PAD4 and disease duration; anti-CCP and erythrocyte sedimentation rate (ESR); anti-MCV and ESR and C-reactive protein. Anti-MCV antibodies were associated with high disease activity score 28 (DAS-28) in early RA. Concentrations of T helper type 1 (Th1) [tumour necrosis factor (TNF)-α, interleukin (IL)-12, IL-2, IL-1β], Th2 (IL-4, IL-6, IL-10, IL-13) and Th17 (IL-17) cytokines were higher in RA than in controls. Th2 and, to a lesser extent, Th1-related cytokines, showed positive correlations with anti-MCV and anti-CCP. The GTG haplotype in PADI4 was associated with anti-CCP and anti-MCV, but not anti-PAD4 antibodies. In conclusion, anti-PAD4 antibodies are detected mainly in established RA, which is in contrast to the early detection of antibodies against citrullinated peptide/proteins (ACPAs). Among autoantibodies, anti-MCV appear to perform better as markers of disease activity. Furthermore, anti-CCP and anti-MCV are associated genetically with the citrullinating enzyme PAD4 and are related strongly to Th1 and Th2 cytokines, suggesting a feed-forward loop between cytokines and ACPA production.

Serum RANKL levels associate with anti- citrullinated protein antibodies in early untreated rheumatoid arthritis and are modulated following methotrexate

INTRODUCTION

Receptor activator of nuclear factor kappa B ligand (RANKL) is a key regulator of bone metabolism. Anti-citrullinated protein antibodies (ACPA) have been suggested to cause bone destruction by osteoclast activation. We investigated the relationship between RANKL and ACPA in patients with early untreated rheumatoid arthritis (RA).

METHODS

Patients with newly diagnosed untreated RA (n = 183) were analyzed at baseline and 3 months after initiating methotrexate (MTX) treatment. Serum RANKL (total RANKL), ACPA (anti-CCP2) and ACPA specificities (anti-citrullinated (cit)-vimentin, anti-cit-enolase and anti-cit-fibrinogen) were determined by enzyme-linked immunosorbent assay (ELISA). Synovial RANKL expression was evaluated by immunohistochemistry in a small group of patients (n = 15). The relationship between anti-cit-vim antibodies and bone destruction was further validated in 1116 RA patients included in the EIRA cohort. Pearson's chi-square test, Wilcoxon rank sum test, Wilcoxon signed rank test and linear regression models were used.

RESULTS

Serum RANKL concentration was significantly higher (p <0.05) in ACPA-positive (median: 689 pmol/L, IQR 342-1253) compared with ACPA-negative (median: 159 pmol/L, IQR 96-243) patients and this difference was also seen for synovial RANKL expression. Serum RANKL associated with ACPA (p <0.05) and bone erosions in rheumatoid factor (RF)-negative patients (n = 59). Among ACPA specificites, anti-cit-vimentin (amino acids 60-75) was associated with higher RANKL concentration and higher prevalence of bone erosion (p <0.05). Significant reductions in both serum RANKL and ACPA levels were observed after 3 months of MTX treatment (p <0.05).

CONCLUSIONS

RANKL was elevated in ACPA-positive and in anti-cit-vimentin-positive patients with early untreated RA and associated with bone erosions. These findings give further support for an early direct pathogenic link between ACPA and bone destruction in RA.

Comparison of two assays to determine anti-citrullinated peptide antibodies in rheumatoid arthritis in relation to other chronic inflammatory rheumatic diseases: assaying anti-modified citrullinated vimentin antibodies adds value to second-generation anti-citrullinated cyclic peptides testing

Determination of anti-citrullinated peptide antibodies (ACPA) plays a relevant role in the diagnosis of rheumatoid arthritis (RA). To date, it is still unclear if the use of several tests for these autoantibodies in the same patient offers additional value as compared to performing only one test. Therefore, we evaluated the performance of using two assays for ACPA: second-generation anti-citrullinated cyclic peptides antibodies (anti-CCP2) and anti-mutated citrullinated vimentin (anti-MCV) antibodies for the diagnosis of RA. We compared three groups: RA (n = 142), chronic inflammatory disease (CIRD, n = 86), and clinically healthy subjects (CHS, n = 56) to evaluate sensitivity, specificity, predictive values, and likelihood ratios (LR) of these two assays for the presence of RA. A lower frequency of positivity for anti-CCP2 was found in RA (66.2%) as compared with anti-MCV (81.0%). When comparing RA versus other CIRD, sensitivity increased when both assays were performed. This strategy of testing both assays had high specificity and LR+. We conclude that adding the assay of anti-MCV antibodies to the determination of anti-CCP2 increases the sensitivity for detecting seropositive RA. Therefore, we propose the use of both assays in the initial screening of RA in longitudinal studies, including early onset of undifferentiated arthritis.

Primary bone marrow oedema syndromes

MRI scanning in patients with rheumatological conditions often shows bone marrow oedema, which can be secondary to inflammatory, degenerative, infective or malignant conditions but can also be primary. The latter condition is of uncertain aetiology and it is also uncertain whether it represents a stage in the progression to osteonecrosis in some patients. Patients with primary bone marrow oedema usually have lower limb pain, commonly the hip, knee, ankle or feet. The diagnosis is one of exclusion with the presence of typical MRI findings. Treatment is usually conservative and includes analgesics and staying off the affected limb. The natural history is that of gradual resolution of symptoms over a number of months. Evidence for medical treatment is limited, but open-label studies suggest bisphosphonates may help in the resolution of pain and improve radiological findings. Surgical decompression is usually used as a last resort.

Old drugs, old problems: where do we stand in prediction of rheumatoid arthritis responsiveness to methotrexate and other synthetic DMARDs?

Methotrexate (MTX) is the central drug in the management of rheumatoid arthritis (RA) and other immune mediated inflammatory diseases. It is widely used either in monotherapy or in association with other synthetic and biologic disease modifying anti-rheumatic drugs (DMARDs). Although comprehensive clinical experience exists for MTX and synthetic DMARDs, to date it has not been possible to preview correctly whether or not a patient will respond to treatment with these drugs. Predicting response to MTX and other DMARDs would allow the selection of patients based on their likelihood of response, thus enabling individualized therapy and avoiding unnecessary adverse effects and elevated costs. However, studies analyzing this issue have struggled to obtain consistent, replicable results and no factor has yet been recognized to individually distinguish responders from nonresponders at treatment start. Variables possibly influencing drug effectiveness may be disease-, patient- or treatment-related, clinical or biological (genetic and nongenetic). In this review we summarize current evidence on predictors of response to MTX and other synthetic DMARDs, discuss possible causes for the heterogeneity observed and address its translation into daily clinical practice.

[Personalized medicine for rheumatoid arthritis : serological and clinical patient profiles to optimize B and T cell targeted therapy]

Nowadays B and T-cell directed biologics in addition to TNF inhibitors are established as effective and safe treatment options for rheumatoid arthritis. As shown by the approval of rituximab for the treatment of systemic vasculitis, these drugs can also be useful for the treatment of other systemic autoimmune diseases; however, to optimize therapeutic strategies, predictive factors for treatment response as well as a good characterized safety profile are essential. So far implementation of real personalized medicine is not feasible in the field of rheumatology, but first biomarkers have already been identified and provide promising results. In this context, it has been shown that a B-cell directed therapy with rituximab is more effective in seropositive patients with rheumatoid arthritis. In addition, characterization of the cytokine milieu as well as of circulating and tissue infiltrating B and T-cell subsets might be useful for prediction of treatment response in the near future.

Unique correlation between mutated citrullinated vimentine IgG autoantibodies and markers of systemic inflammation in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is the most common inflammatory systemic autoimmune disease, primarily affecting the peripheral joints. Anti-mutated citrullinated vimentin autoantibodies (anti-MCV) of IgG isotype were shown to be a useful diagnostic marker of RA especially in RA patients who were anti-cyclic citrullinated protein autoantibodies (anti-CCP) negative. Nevertheless, published data correlates rheumatoid factor (RF), anti-CCP or anti-MCV antibodies with either erythrocyte sedimentation rate (ESR) or serum C-reactive protein (CRP) as markers of disease activity, not investigated the possible correlations of RA autoantibodies towards ESR and CRP in comparison. Herein, we aim to evaluate the usefulness of anti-MCV as a dependable marker in established RA compared with anti-CCP and RF antibodies and to examine correlations between RF, anti-CCP and anti-MCV antibodies towards ESR and serum CRP. Serum RF-IgA, RF-IgM, anti-CCP and anti-MCV levels were measured in 30 patients with RA and 40 patients with other autoimmune diseases (non-RA) compared with 20 normal subjects. Specificity, sensitivity and AUC for RF antibodies, anti-CCP and anti-MCV were calculated towards RA diagnosis. Our results showed that ESR and CRP had significantly higher values in both RA and non-RA patients compared with our healthy controls with observed significant increment in RA patients compared with non-RA patients. An important finding from our study is that 33.3 % of RA patients were anti-CCP negative but being positive towards anti-MCV. Also, in-between 36.7 up to 40 % of RA patients were RF-IgA and RF-IgM negative while being anti-MCV positive. Anti-MCV antibodies showed the highest specificity and sensitivity (97.5 and 86.6 %, respectively) towards RA diagnosis with the highest AUC value (0.920) compared with anti-CCP and RF antibodies. Correlation analyses revealed that there was no significant correlation between ESR along with CRP towards RF-IgA, RF-IgM and anti-CCP while profound highly significant correlation exhibited between ESR and CRP towards anti-MCV data (r = 0.879 and 0.994, respectively). Thus, our data suggest that the assessment of serum anti-MCV autoantibodies along with ESR and CRP considered as a simple laboratory regime for monitoring RA patients to assess and follow-up disease activity. The addition of anti-MCV autoantibodies to serologic markers in the ACR/EULAR classification criteria for RA will add points for patients with negative anti-CCP and RF antibodies.

Evaluation of anti-mutated citrullinated vimentin antibodies, anti-cyclic citrullinated Peptide antibodies and rheumatoid factor in omani patients with rheumatoid arthritis

Rheumatoid factor (RF) is currently used in the diagnosis of rheumatoid arthritis (RA). The discovery of anticitrullinated protein autoantibodies has led to the development of various new tests, such as anti-cyclic citrullinated peptide (anti-CCP) antibodies, and anti-mutated citrullinated vimentin (anti-MCV) antibodies, to diagnose RA. The aims of this study were to determine the sensitivity and specificity of anti-MCV antibodies in comparison with anti-CCP antibodies and RF in Omani Arab patients with RA and compare our findings with published values from different ethnic groups. The sensitivity of anti-MCV antibodies was 72% with 87% specificity. For anti-CCP antibodies the sensitivity was 52% and the specificity was 97%. The sensitivity of RF was 57% with 94% specificity. Anti-CCP antibodies have higher diagnostic specificity and positive predictive value than RF and anti-MCV antibodies. Anti-MCV antibodies have the highest sensitivity when compared to anti-CCP antibodies and RF. Anti-MCV antibodies do not appear to be very useful in the diagnosis of RA. However, long-term study is required to find out whether anti-MCV antibodies can be used as predictive test for incidence of RA.

Antibodies to mutated citrullinated vimentin in patients with chronic hepatitis C virus genotype IV infection-related arthropathy

One of the extra-hepatic manifestations of hepatitis C virus (HCV) infection is polyarthritis that mimics rheumatoid arthritis (RA). Anti-mutated citrullinated vimentin (MCV) was recently introduced in the diagnostic workup of RA, but its exact role in HCV infection and its related arthropathy is still unclear. The aim of the study is to determine the prevalence of anti-MCV antibodies in HCV-infected patients with or without articular involvement, and to investigate whether anti-MCV antibodies have an additional role to anticyclic citrullinated peptide (CCP) antibodies and rheumatoid factor (RF) in differentiating patients with RA from patients with HCV-related arthropathy. Fifty-five HCV-infected patients (HCV RNA positive) and 30 RA patients (fulfilling the American College of Rheumatology classification criteria for RA and negative for HCV) were included. Anti-MCV antibodies, anti-CCP antibodies, RF and cryoglobulins were measured. Articular involvement in hepatitis C patients was evaluated. Articular involvement was detected in 30/55 (54.5%) of HCV-infected patients. The most frequent pattern was symmetric polyarthralgias and the most frequent joints to be involved were the wrists, metacarpophalangeal joints, shoulders and knees. In HCV arthropathy, anti-MCV was positive in 9/30 (30%), anti-CCP in 0% and RF in 22/30 (73.3%). Whereas, in chronic HCV without arthropathy, anti-MCV was positive in 8 patients (32%), anti-CCP in one patient (4%) and RF in 23/25 (92.0%). There was no significant difference between the two HCV groups as regards the frequencies of anti-MCV (P = 0.89), anti-CCP (P = 0.93) and RF (P = 0.15). In RA, anti-MCV was positive in 93.3% anti-CCP in 96.7% and RF in 86.7%. There was no significant difference in RF between RA and HCV arthropathy (P = 0.33). Meanwhile, there was a highly significant difference between both groups regarding anti-MCV and anti-CCP (P < 0.0001 for each). The sensitivity of anti-MCV, anti-CCP and RF for RA was 93.3, 96.7 and 86.7%, respectively. Whereas their specificity was 69.1, 98.2 and 18.2%, respectively. In addition, the mean levels of anti-MCV and anti-CCP were significantly increased in RA than in all HCV patients (P = 0.038 and P < 0.0001, respectively). Meanwhile, there were no significant differences in mean levels of anti-MCV and anti-CCP between HCV patients with arthropathy and those without arthropathy (P = 0.11 and P = 0.73, respectively). Also, there were no differences in mean RF between both HCV groups. There was a significant positive correlation between anti-MCV and anti-CCP levels in patients with HCV-related arthropathy (r = 0.39, P = 0.032) and in those without arthropathy (r = 0.578, P = 0.002). Cryoglobulins were detected in 7/30 HCV-related arthropathy (23.3%) and were positively correlated with anti-MCV(r = 0.485, P = 0.007). Anti-CCP still attains the major role in differentiating RA from HCV arthropathy. Anti-MCV seems to play no additional role in this aspect. The role of mutation of vimentin in the pathogenesis of HCV arthropathy is not as clear as it is for RA and needs further investigation.

Mutated citrullinated vimentin antibodies in rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common inflammatory systemic autoimmune disease, primarily affecting the peripheral joints. The past decade has been marked with revolutionary changes both in the therapeutic and diagnostic perspectives of RA. The discovery of an RA-specific citrullination-driven immune reaction gave a substantial contribution in the diagnostic approach to RA. Efforts directed towards the identification of the antigenic target specifically recognized by these autoantibodies resulted in the identification of vimentin in citrullinated form as the potential native antigen, among other proteins. Furthermore, it was found that the mutation of vimentin represents an independent trigger of antigenic properties, in addition to citrullination. As a result of this discovery, a commercial ELISA using mutated citrullinated vimentin (MCV) was developed. Increasingly, data now support the use of anti-MCV in RA diagnosis and prognosis for errosion. This review summarizes the research to date on the use of anti-MCV in RA diagnosis and prognosis and its potential use as a therapeutic marker. The pathologic role of these antibodies in RA disease is also discussed.

A systematic review of serum biomarkers anti-cyclic citrullinated Peptide and rheumatoid factor as tests for rheumatoid arthritis

This systematic review assesses the current status of anti-cyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF) tests in the diagnosis and prognosis of rheumatoid arthritis (RA). We reviewed publications on tests and biomarkers for early diagnosis of RA from English-language MEDLINE-indexed journals and non-MEDLINE-indexed sources. 85 publications were identified and reviewed, including 68 studies from MEDLINE and 17 non-MEDLINE sources. Anti-CCP2 assays provide improved sensitivity over anti-CCP assays and RF, but anti-CCP2 and RF assays in combination demonstrate a positive predictive value (PPV) nearing 100%, greater than the PPV of either of the tests alone. The combination also appears to be able to distinguish between patients whose disease course is expected to be more severe and both tests are incorporated in the 2010 ACR Rheumatoid Arthritis Classification Criteria. While the clinical value of anti-CCP tests has been established, differences in cut-off values, sensitivities and specificities exist between first-, second- and third-generation tests and harmonization efforts are under way. Anti-CCP and RF are clinically valuable biomarkers for the diagnosis and prognosis of RA patients. The combination of the two biomarkers in conjunction with other clinical measures is an important tool for the diagnosis and management of RA patients.

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.

Association of anti-modified citrullinated vimentin with subclinical atherosclerosis in early rheumatoid arthritis compared with anti-cyclic citrullinated peptide

OBJECTIVE

To investigate anti-modified citrullinated vimentin (anti-MCV) in early rheumatoid arthritis (RA), including correlation with disease activity and cardiovascular risk factors, compared with anti-cyclic citrullinated peptides (anti-CCP3).

METHODS

Anti-MCV and anti-CCP3 concentrations were measured in 100 patients with early RA and 100 healthy controls at baseline to determine sensitivity and specificity. Patients received methotrexate (MTX) 0.2 mg/kg/week plus prednisone 10 mg/day. Anti-MCV, anti-CCP3, rheumatoid factor (RF), Disease Activity Score for 28 joints (DAS-28), lipid profile, erythrocyte sedimentation rate (ESR), high-sensitivity C-reactive protein assay (hsCRP), homeostasis model assessment for insulin resistance (HOMA-IR) index, tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and carotid intima-media thickness (cIMT) were measured before and after 12 months of treatment.

RESULTS

The sensitivity and specificity for anti-MCV antibody were 75% and 90%, respectively, and for anti-CCP3 antibody 71% and 96%. Serum anti-MCV and serum anti-CCP3 levels at baseline were positively correlated with hsCRP, IL-6, HOMA-IR index, serum RF levels (p < 0.001), and cIMT (p < 0.05). Serum anti-MCV was positively correlated with serum anti-CCP3 levels. There were significant positive correlations between the percentage of changes of anti-MCV levels versus changes in DAS-28, ESR, hsCRP, atherogenic ratios (TC/HDL-C and LDL-C/HDL-C), apolipoprotein A-I, IL-6, TNF-α, HOMA-IR index, and cIMT. These correlations were not found between changes in anti-CCP3 levels compared to clinical, laboratory, and radiological variables.

CONCLUSION

Anti-MCV was as sensitive as anti-CCP3 in diagnosing early RA. Anti-MCV testing appears to be useful for monitoring associated subclinical atherosclerosis in early RA.

The relevance of citrullinated vimentin in the production of antibodies against citrullinated proteins and the pathogenesis of rheumatoid arthritis

Antibodies against citrullinated proteins (ACPAs) are highly specific for RA. Since the discovery of these antibodies, several of studies that focused on the presence and identity of citrullinated proteins in the joints of RA patients have been carried out. The best-known antigens that bind ACPAs are citrullinated filaggrin, Type II collagen (CII), α-enolase, fibrinogen and vimentin. This review compares citrullinated filaggrin, CII, α-enolase and fibrinogen with vimentin in their contribution to ACPA triggering, and gives an overview of the literature in which the role of citrullinated and non-citrullinated vimentin in the onset of ACPA production and the pathogenesis of RA is discussed.

[Rituximab]

Rituximab as a monoclonal antibody against CD20 was approved for treatment of patients with rheumatoid arthritis (RA) with inadequate response to or contraindication for the use of a TNF blocker. This article focuses on current results from clinical trials at different developmental stages as well as from registry data in anti-TNF non-responders regarding the documented efficacy with respect to RA activity, radiological progression and improvement of functional indices. The available safety data for rituximab for this particular indication showed that the overall risk of infection, including severe manifestations, is not further increased. The occurrence of progressive multifocal leukoencephalopathy (PML) after rituximab requires further observation; the risk has currently been estimated at about 1:15.000-20.000 of RA patients treated. Of relevance, decreased IgG levels prior to treatment have been reported to be associated with a substantially increased risk for infections, and therefore, in such cases other treatment options should be considered.

Immediate determination of ACPA and rheumatoid factor--a novel point of care test for detection of anti-MCV antibodies and rheumatoid factor using a lateral-flow immunoassay

Introduction

Autoantibodies against mutated and citrullinated vimentin (MCV) represent a novel diagnostic marker for rheumatoid arthritis (RA). Recently, an increased sensitivity for anti-MCV compared to autoantibodies against cyclic citrullinated peptides (anti-CCP2) was shown in cohorts of patients with early RA and established disease.

The aim of this study was to develop and evaluate a point of care test (POCT) for detection of anti-MCV antibodies immediately at the first visit or at the bed side.

Methods

A lateral-flow immunoassay was developed for simultaneous detection of anti-MCV antibodies and rheumatoid factor (RF-IgG) and evaluated in a prospective setting. Analyses were performed from whole blood samples of patients with seropositive RA (n = 108), seronegative RA as well as other rheumatic disorders (n = 122), and healthy blood donors (n = 200) and compared to detection via ELISA.

Results

Using the POCT, anti-MCV antibodies were detected in 54.6% and RF-IgG in 56.5% of patients with RA. Specificity was 99.1% for anti-MCV antibodies and 91.2% for RF-IgG. Compared to ELISA's results, POCT sensitivity was 69.3% for anti-MCV and 55.6% for RF-IgG, specificity was 99.7% and 97.2%, respectively.

Conclusions

This POCT for detection of anti-MCV antibodies and RF-IgG provides high specificity for the diagnosis of RA and is useful in clinical practice due to its simplicity and its reliable performance. This test can greatly improve a timely management of RA and may help in screening patients with suspected RA in non-specialized settings prompting early referrals.

Autoimmunity to specific citrullinated proteins gives the first clues to the etiology of rheumatoid arthritis

Rheumatoid arthritis (RA) is now clearly a true autoimmune disease with accumulating evidence of pathogenic disease-specific autoimmunity to citrullinated proteins. Citrullination, also termed deimination, is a modification of arginine side chains catalyzed by peptidylarginine deiminase (PAD) enzymes. This post-translational modification has the potential to alter the structure, antigenicity, and function of proteins. In RA, antibodies to cyclic citrullinated peptides are now well established for clinical diagnosis, though we argue that the identification of specific citrullinated antigens, as whole proteins, is necessary for exploring pathogenic mechanisms. Four citrullinated antigens, fibrinogen, vimentin, collagen type II, and alpha-enolase, are now well established, with others awaiting further characterization. All four proteins are expressed in the joint, and there is evidence that antibodies to citrullinated fibrinogen and collagen type II mediate inflammation by the formation of immune complexes, both in humans and animal models. Antibodies to citrullinated proteins are associated with HLA 'shared epitope' alleles, and autoimmunity to at least one antigenic sequence, the CEP-1 peptide from citrullinated alpha-enolase (KIHAcitEIFDScitGNPTVE), shows a specific association with HLA-DRB1*0401, *0404, 620W PTPN22, and smoking. Periodontitis, in which Porphyromonas gingivalis is a major pathogenic bacterium, has been linked to RA in epidemiological studies and also shares similar gene/environment associations. This is also the only bacterium identified that expresses endogenous citrullinated proteins and its own bacterial PAD enzyme, though the precise molecular mechanisms of bacterial citrullination have yet to be explored. Thus, both smoking and Porphyromonas gingivalis are attractive etiological agents for further investigation into the gene/environment/autoimmunity triad of RA.

Meta-analysis: diagnostic value of serum anti-mutated citrullinated vimentin antibodies in patients with rheumatoid arthritis

Conventional tests are not always helpful in making a diagnosis of rheumatoid arthritis (RA). This study aimed to comprehensively and quantitatively summarize the evidence on the accuracy of anti-mutated citrullinated vimentin (MCV) assay in the diagnosis of RA. A comprehensive meta-review of data on the accuracy of MCV concentrations in the diagnosis of RA were carried out from 16 published studies. Furthermore, receiver operating characteristic curves were used to summarize the overall test performance. The summary estimates for MCV in the diagnosis of RA were: sensitivity 0.77 [95% confidence interval (CI) 0.75-0.78], specificity 0.89 (95% CI 0.87-0.90), positive likelihood ratio (LR+) 7.24 (95% CI 5.60-9.36), negative likelihood ratio (LR-) 0.28 (95% CI 0.23-0.34) and diagnostic odds ratio 29.66 (95% CI 21.09-41.71). The area under the summary receiver operating characteristic curves was 0.92. Data from meta-analysis suggest the accuracy of MCV assay in the diagnosis of RA is high, but ultimately clinician must consider the results of MCV tests combing with other conventional examinations and the clinical feature.

The use of citrullinated peptides and proteins for the diagnosis of rheumatoid arthritis

The presence or absence of antibodies to citrullinated peptides/proteins (ACPA) is an important parameter that helps a clinician set a diagnosis of early rheumatoid arthritis and, hence, initiate treatment. There are several commercial tests available to measure ACPA levels, although it can be difficult to decide what the best test for a given clinical question is. We analyzed literature data in which the diagnostic and other properties of various ACPA tests are compared. The results show that for diagnostic purposes the CCP2 test has the highest specificity, the highest sensitivity in stratified studies and the highest positive predictive value. For the prediction of future joint destruction the CCP2, MCV, and CCP3 tests may be used. The ability to predict the likelihood of not achieving sustained disease-modifying antirheumatic drug-free remission was highest for the CCP2 test. Finally, the levels of anti-CCP2 and anti-CCP3 (and possibly anti-mutated citrullinated vimentin) in rheumatoid arthritis patients are not significantly influenced by TNFalpha blocking agents.

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

BACKGROUND

The goal of the study was to assess the presence of antibodies to mutated citrullinated vimentin (anti-MCV) and cyclic citrullinated peptides (anti-CCP) in patients with juvenile idiopathic arthritis (JIA) compared with patients with other juvenile onset rheumatic diseases.

METHODS

The study included 56 patients who fulfilled the International League of Associations for Rheumatology (ILAR) classification criteria for JIA, and 17 control patients with other juvenile onset rheumatic diseases. Data on six core outcome variables and the Sharp score were collected for patients with JIA. Sera and synovial fluid, if available, were tested for anti-CCP and anti-MCV antibodies using a commercial enzyme-linked immunosorbent assay (ELISA).

RESULTS

Anti-MCV antibodies were positive in 3/56 (5.4%) and anti-CCP in 1/56 (1.8%) of patients with JIA. Two out of three anti-MCV positive patients (one of them also anti-CCP positive) were found to be rheumatoid factor (RF)-positive with polyarticular disease. Within the control group, anti-MCV was positive in 4/17 (23.5%) patients, while anti-CCP positivity was not observed. No correlation between anti-MCV with anti-CCP antibody levels was found for any of the six core outcome variables or for the adapted Sharp score.

CONCLUSIONS

Our results show that antibodies targeting citrullinated proteins are not a useful diagnostic marker for JIA, but can indicate severe patterns of disease in JIA.

Differentiation of Rheumatoid Arthritis From HCV Infection: Rheumatoid Factor, Anti-Cyclic Citrullinated Peptide or Anti-Mutated Citrullinated Vimentin?

Objective: Differentiation of rheumatoid arthritis (RA) from other diseases with joint involvement such as hepatitis-C virus (HCV) infection represents a diagnostic problem. In addition to the rheumatoid factor (RF), more specific and sensitive auto-antibodies are under evaluation in recent years with conflicting results. In this study, we tested the diagnostic value of rheumatoid factor, anti-cyclic citrullinated peptide (anti-CCP) and anti-mutated citrullinated vimentin (anti-MCV) in distinguishing RA from hepatitis C patients.

Materials and Methods: Sera of 34 RA patients and 30 hepatitis C patients were tested for RF, anti-CCP anti-MCV. Disease activity was determined by disease activity score (DAS-28) 28 in RA and by modified Knodell score in hepatitis C patients. Extra-articular involvement in RA and rheumatologic involvement in hepatitis C patients were documented.

Results: In roc analysis, area under curve (AUC) was the highest in anti-CCP. Sensitivity and specificity was 82% and 53%, 79%, and 96% and 70%, and 73% for RF, anti-CCP and anti-MCV respectively. DAS-28 has a weak correlation with RF (r=0.406), anti-CCP (r=0.433), and anti-MCV (r=0.453). There was no difference between the patients in autoantibody levels regarding extra-articular involvement and DAS-28 in RA, and joint involvement in hepatitis C patients.

Conclusion: Anti-MCV antibodies may be useful in distinguishing RA however it seems to have no additional value over anti-CCP or RF in hepatitis C patients. Anti-CCP antibodies are more reliable in diagnosis of RA due to their high specificity. (Turk J Rheumatol 2010; 25: 19-23)

[Antibodies against citrullinated peptides in clinical practice and research]

Since their original description ten years ago, antibodies against citrullinated peptide antigens (ACPA) have become increasingly important in the diagnosis of rheumatoid arthritis (RA). They are now considered superior to the rheumatoid factor because they can be detected earlier in the course of the disease and are more specific while showing a comparable sensitivity. However, they seem to be less suitable for monitoring specific responses to therapies and for predicting extra-articular manifestations as well as disease activity. Recent research activities center around using ACPA to further elucidate the pathogenesis of RA.

The role of anti-mutated citrullinated vimentin antibodies in the diagnosis of early rheumatoid arthritis

OBJECTIVE

Anti-mutated citrullinated vimentin (MCV) antibodies have been reported as a fairly sensitive serological marker of rheumatoid arthritis (RA). We evaluated the diagnostic value of anti-MCV in a large cohort of Chinese patients with early RA.

METHODS

One hundred seventy patients with early RA (<1 yr duration), 66 with other rheumatic diseases, 10 with infectious diseases, and 60 healthy individuals were included in our study. Serum anti-MCV and second-generation anti-cyclic citrullinated peptide antibodies (anti-CCP2) were measured by ELISA, and rheumatoid factor (RF) was measured by rate nephelometry. The associated clinical data of patients with early RA were also evaluated. Then disease activity was scored by the formula for Disease Activity Score (DAS)28, and the degree of radiological changes was assessed by Sharp score.

RESULTS

The prevalence of serum anti-MCV in patients with early RA (78.2%, 133/170) was significantly higher than that of other rheumatologic patients and patients with infectious diseases. It was 12% (3/25) in systemic lupus erythematosus, 9.5% (2/21) in primary Sjögren's syndrome, 10% (1/10) in systemic sclerosis, 20% (2/10) in ankylosing spondylitis, 12.5% (1/8) in viral hepatitis type B, and 0% (0/2) in tuberculosis. Anti-MCV was not found in the serum of healthy subjects. The sensitivities of anti-MCV, anti-CCP2, and RF tests for early RA were 78.2%, 61.8%, and 72.4%, respectively, and the specificities were 93.4%, 96.3%, and 80.1%. The combination of anti-MCV and anti-CCP2 positivity showed a very high specificity (97.8%) and positive predictive value (97.1%), but a low sensitivity (58.8%). The sensitivity reached 81.2% when the union of anti-MCV and anti-CCP2 positivities was used as one combined criterion. Statistically, anti-MCV had significant correlation with anti-CCP2 (r=0.587, p=0.01, 2-tailed) and RF (r=0.389, p=0.01, 2-tailed). In addition, it had an interesting correlation with radiological assessment (r=0.349, p=0.05, 2-tailed). The anti-MCV had no significant correlation with other factors, such as erythrocyte sedimentation rate, C-reactive protein, antikeratin antibody, antiperinuclear factor, global visual analog scale score for joint pain, IgA, IgG, IgM, C3, C4, hidden rheumatoid factor for IgA (HRFIgA), HRFIgG, and DAS28.

CONCLUSION

Anti-MCV is a novel diagnostic marker for early RA. It may be more useful if the anti-CCP2 assay is performed concomitantly to diagnose patients with early RA.

The serological diagnosis of rheumatoid arthritis: antibodies to citrullinated antigens

BACKGROUND

This article provides an overview of modern serological diagnostic testing for rheumatoid arthritis (RA) involving the detection of antibodies against citrullinated peptides/proteins (ACPA). Recommendations are also given for differential diagnosis and sequential testing in rheumatoid arthritis, with a view towards improving early diagnosis, so that irreparable joint damage can be avoided.

METHODS

Selective literature research, with consideration of the authors' own publications.

RESULTS

Two different, adequately evaluated testing systems, involving the detection of anti-CCP antibodies and of anti-MCV antibodies, are now commercially available and enable routine, relatively highly specific diagnostic testing for RA. Two point-of-care tests (POCT) for the early diagnosis of RA constitute the latest development in serologic diagnostic testing.

CONCLUSIONS

The two ACPA assays now on the market are equally useful for the diagnosis of rheumatoid arthritis. The correlation between RA disease activity and stratification with ACPA has only been demonstrated to date through the detection of anti-MCV antibodies.

Antibodies to mutated citrullinated vimentin for diagnosing rheumatoid arthritis in anti-CCP-negative patients and for monitoring infliximab therapy

Introduction

Antibodies against cyclic citrullinated peptides (CCPs) are useful for diagnosing rheumatoid arthritis (RA). Antibodies to mutated citrullinated vimentin (MCV) were described recently in RA. The aims of this study were to evaluate the usefulness of anti-MCV for diagnosing RA in anti-CCP-negative patients and to monitor anti-MCV titres during infliximab therapy for RA.

Methods

We studied two groups of RA patients, one with (n = 80) and one without (n = 76) anti-CCP antibodies. The specificity of anti-MCV was evaluated by investigating 50 healthy controls and 158 patients with other rheumatic diseases (51 psoriatic rheumatism, 58 primary Sjögren syndrome, and 49 ankylosis spondylitis). Serum anti-MCV and anti-CCP titres were measured in 23 patients after 6, 12, 18, and 24 months of infliximab treatment. Anti-CCP2 and anti-MCV levels were assayed using a commercial enzyme-linked immunosorbent assay. IgM rheumatoid factor was determined by nephelometry.

Results

In accordance with the cutoff values recommended by the manufacturer, the specificity of anti-MCV antibodies was 90.9%. We adjusted the cutoff values to obtain the same specificity as that of anti-CCP antibodies (94.2%). With this optimal cutoff, anti-MCV antibodies were found in 11.8% (9/76) of RA patients without anti-CCP, and similarly, anti-CCP antibodies were found in 11.2% (9/80) of RA patients without anti-MCV. Anti-MCV antibodies were positive in 6 patients who tested negative for both anti-CCP and rheumatoid factor. Anti-MCV titres were significantly decreased after 18 and 24 months of infliximab therapy compared with baseline (P < 0.01) as a significant decrease of anti-CCP levels occurred only at 24 months (P < 0.04). Moreover, an anti-MCV decrease was significantly associated with DAS28 (disease activity score using 28 joint counts) improvements 12 months into therapy.

Conclusions

Our results suggest that anti-MCV antibodies may be valuable for diagnosing RA in anti-CCP-negative patients without replacing them as an equivalent number of anti-CCP-positive RA patients test negative for anti-MCV. Moreover, anti-MCV antibodies could be useful for monitoring the effects of infliximab therapy.

Rheumatoid arthritis diagnosis with antimutated citrullinated vimentin ELISA by Orgentec Diagnostika

BACKGROUND

There is a need for highly sensitive and specific laboratory tests for the early diagnosis of rheumatoid arthritis (RA). Anticitrullinated protein/peptide antibodies are produced in the sera of RA patients.

OBJECTIVE

To assess and discuss the diagnostic value of Orgentec antimutated citrullinated vimentin (anti-MCV) ELISA and to compare this diagnostic to commercially available anticyclic citrullinated peptide (anti-CCP) tests.

METHODS

The evaluation is based on our recently published study on the comparison of anti-MCV and anti-CCP2 tests, as well as on published studies.

RESULTS/CONCLUSION

In established RA, the anti-MCV ELISA exerts a specificity comparable with anti-CCP2. Numerous recent studies suggest that anti-MCV may have higher sensitivity, however there are also some publications stating the opposite. In early RA, anti-MCV may be a better predictor of disease activity and radiological progression than anti-CCP tests.