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

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.

Advances in the diagnosis of autoimmune diseases based on citrullinated peptides/proteins

Introduction: Autoimmune diseases are still one of the hard obstacles associated with humanity. There are many exogenous and endogenous etiological factors behind autoimmune diseases, which may be combined or dispersed to stimulate the autoimmune responses. Protein citrullination represents one of these factors. Harnessing specific citrullinated proteins/peptides could early predict and/or diagnose some of the autoimmune diseases. Many generations of diagnostic tools based on citrullinated peptides with comparable specificity/sensitivity are available worldwide.Areas covered: In this review, we discuss the deimination reaction behind the citrullination of most known autoantigens targeted, different generations of diagnostic tools based on citrullinated probes with specificity/sensitivity of each as well as newly developed assays. Furthermore, the most advanced molecular analytical tools to detect the citrullinated residues in the biological fluid and their performance are also evaluated, providing new avenues to early detect autoimmune diseases with high accuracy.Expert opinion: With the current specificity/sensitivity tools available for autoimmune disease detection, emphasis must be placed on developing more advance and effective, early, rapid, and simple diagnostic devices for autoimmune disease monitoring (similar to a portable device for sugar test at home). The molecular analytical devices with dual and/or multiplexe functions should be more simplified and invested in clinical laboratories.

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.

Meta-analysis: compared with anti-CCP and rheumatoid factor, could anti-MCV be the next biomarker in the rheumatoid arthritis classification criteria?

Background

Previous reviews of the diagnosis for rheumatoid arthritis (RA) have not compared anti-mutated citrullinated vimentin (MCV) with anti-cyclic citrullinated peptide (CCP) and rheumatoid factor (RF) in respect of sensitivity, specificity and the area under the curve (AUC) against disease controls for differential diagnosis. This meta-analysis aims to evaluate the value of anti-MCV in the diagnosis for RA, the combined sensitivity of anti-MCV and anti-CCP, and certain clinical characteristics related to the performance of anti-MCV.

Methods

Medline, Embase, Cochrane Library and Web of Science were searched for articles published up to 25 August 2018. A total of 33 studies including 6044 RA patients and 5094 healthy or disease controls achieved inclusive criteria. QUADAS-2 was applied to evaluate the quality of the included studies. The bivariate random effects model was employed in primary data synthesis to evaluate the diagnostic performance.

Results

The sensitivity of anti-MCV, anti-CCP and RF in RA diagnosis against a disease control group was 0.71, 0.71, 0.77, with the specificity of 0.89, 0.95, 0.73, and the AUC of the SROC of 0.89, 0.95, 0.82, respectively. The predesign of the primary study and diagnostic criteria were statistically significant as sources of heterogeneity. Anti-MCV and anti-CCP tests demonstrated a sensitivity of 0.77 when performed in parallel, with a sensitivity of 0.60 when performed in series; whereas, the combination of anti-MCV and RF presented a sensitivity of 0.64 when used in series.

Conclusions

Anti-MCV demonstrates comparable diagnostic value to anti-CCP and RF, thus it can be an effective diagnostic marker for RA and may be written into the next authoritative criteria.

Meta-Analysis: Diagnostic Accuracy of Anti-Carbamylated Protein Antibody for Rheumatoid Arthritis

OBJECTIVE

The anti-carbamylated protein (CarP) antibody is a novel biomarker that might help in the diagnosis of rheumatoid arthritis (RA). We aim to assess the diagnostic value of anti-CarP antibody for RA.

METHODS

We systematically searched PubMed, Embase, the Cochrane Library, Web of Science, and Scopus for studies published by December 15, 2015. Studies in any language that evaluated the utility of the anti-CarP antibody in the diagnosis of RA in which healthy donors or patients without arthritis or arthralgia served as controls were included. Two investigators independently evaluated studies for inclusion, assessed study quality and abstracted data. A bivariate mixed-effects model was used to summarize the diagnostic indexes from 7 eligible studies.

RESULTS

The pooled sensitivity, specificity, and positive and negative likelihood ratios for anti-CarP antibody were 42% (95% CI, 38% to 45%), 96% (95% CI, 95% to 97%), 10.2 (95% CI, 7.5 to 13.9), and 0.61 (95% CI, 0.57 to 0.65), respectively. The summary diagnostic odds ratio was 17 (95% CI, 12 to 24), and the area under summary receiver operator characteristic curve was 80% (95% CI, 77% to 84%).

CONCLUSION

Anti-CarP antibody has a moderate value in the diagnosis of RA with high specificity but relatively low sensitivity.

Restrictive IgG antibody response against mutated citrullinated vimentin predicts response to rituximab in patients with rheumatoid arthritis

Introduction

Antibodies against mutated citrullinated vimentin (AMCV) represent a useful diagnostic marker with correlation to disease activity in patients with rheumatoid arthritis (RA). Since seropositivity for citrullinated autoantibodies was predictive for response to B-cell depleting therapy (BCDT) with rituximab (RTX), we investigated whether differences in antibody fine reactivity and immunoglobulin (Ig) isotype kinetics among AMCV-positive patients could provide additional information about outcome.

Methods

A total of 50 AMCV IgG-positive RA patients (RTX responders (RRs) n = 37 and non-responders (NRRs) n = 13) were analyzed for reactivity against MCV epitopes and co-existent AMCV isotypes IgM and IgA. Antibody titers were determined by enzyme-linked immunosorbent assay at baseline and 24 weeks after the first cycle of RTX, and compared to kinetics of rheumatoid factor (RF) and antibodies against cyclic citrullinated peptide (ACCP).

Results

Recognized MCV epitopes by AMCV IgG of RRs and NRRs showed similar baseline patterns, with reducing reactivity in RRs and unchanged or even expanding reactivity in NRRs upon RTX treatment. At baseline, RRs were more frequently negative for AMCV subtypes, especially for IgA (68 %), compared to NRRs (31 %). Being AMCV IgA-negative at baseline indicated a good treatment response to RTX (negative predictive value = 0.86). Co-existence of AMCV IgA and IgG with stable titers upon treatment were associated with poorer responses to RTX. Furthermore, reductions of AMCV IgA levels upon RTX correlated with the improvement of 28-joint Disease Activity Score (DAS28). In comparison, subtypes of RF and ACCP were not of additional value for prediction of RTX response.

Conclusions

Restrictive IgG seropositivity against MCV with treatment-associated decline in fine reactivity and titers was predictive for response to RTX. Double-positivity for AMCV IgG and IgA was associated with failure to respond to BCDT, suggesting a pathogenetic and less sensitive IgA-producing B-cell subset in NRRs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0717-z) contains supplementary material, which is available to authorized users.

Proteoglycan aggrecan conducting T cell activation and apoptosis in a murine model of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease and its targeting of the joints indicates the presence of a candidate autoantigen(s) in synovial joints. Patients with RA show immune responses in their peripheral blood to proteoglycan (PG) aggrecan. One of the most relevant animal models of RA appears to be proteoglycan-induced arthritis (PGIA), and CD4⁺ T cells seem to play a crucial role in the initiation of the disease. In this review, the role of various T cell epitopes of aggrecan in the induction of autoreactive T cell activation and arthritis is discussed. We pay special attention to two critically important arthritogenic epitopes, 5/4E8 and P135H, found in the G1 and G3 domains of PG aggrecan, respectively, in the induction of autoimmune arthritis. Finally, results obtained with the recently developed PG-specific TCR transgenic mice system showed that altered T cell apoptosis, the balance of activation, and apoptosis of autoreactive T cells are critical factors in the development of autoimmunity.

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.

Serum levels of anti-CCP antibodies, anti-MCV antibodies and RF IgA in the follow-up of patients with rheumatoid arthritis treated with rituximab

Rheumatoid arthritis (RA) is characterized by the presence of circulating rheumatoid factor (RF) and anticitrullinated peptide antibodies (ACPA), which are positive in about 70-80% of patients. APCA have a higher specificity and therefore a higher diagnostic power than RF, but are less informative than RF in monitoring the course of the disease in patients under treatment. Recently, it has been reported that the anticitrullinated vimentin (a-MCV) antibody test can identify a particular subgroup of APCA that may be negative for anticyclic citrullinated peptide (a-CCP) antibodies. Concerning RF, the RF IgA isotype has been described as a more specific marker of erosive joint damage than total RF. The aim of our study was to monitor the levels of a-CCP, a-MCV, total RF and RF IgA in the follow-up of patients with RA treated with B-lymphocytedepletive rituximab (RTX), to detect any differences or peculiarities in patterns of these autoantibodies, especially in relation to their potential use as predictive markers of therapeutic response. We studied 30 patients with RA treated with RTX. All patients were previously unresponsive to at least 6 months of therapy with disease-modifying antirheumatic drugs (DMARDs; methotrexate, leflunomide, cyclosporine, chloroquine) and/or at least 6 months of therapy with anti-TNF biologics. The evaluation of response to RTX was made at month +6 using the EULAR criteria (DAS28). a-CCP, a-MCV, total RF and RF IgA were determined at baseline (before the first infusion of RTX) and after 1, 3 and 6 months. In serum samples obtained before treatment two cytokines essential for Blymphocyte proliferation, interleukin 6 (IL-6) and B-lymphocyte stimulator (BLyS) were also determined. In all patients a significant and consistent reduction in all the tested antibodies was found during follow-up, with no differences in respect of the degree of response to RTX. Of note, at baseline, generally a higher titre of all autoantibodies was seen in patients who then showed a better response to RTX. Finally, there were no differences in serum concentrations of IL-6 and BLyS in patients in relation to the presence or absence of the autoantibodies investigated, nor was there any significant correlation between the serum concentrations of the cytokines and the titres of the autoantibodies. Thus, neither a-MCV compared to a- CCP, nor RF IgA compared to routine total RF, provided any additional predictive information in the follow-up of patients with RA treated with RTX.