Association of anti-cyclic citrullinated peptide antibodies, anti-citrullin antibodies, and IgM and IgA rheumatoid factors with serological parameters of disease activity in 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.

Rheumatoid factor isotypes in rheumatoid arthritis diagnosis and prognosis: a systematic review and meta-analysis

OBJECTIVE

The first biomarker associated with the rheumatoid arthritis is rheumatoid factor (RF) and since the earliest reports a role has been proposed in the diagnosis and in the prediction of clinical features and outcome. The study of RF isotypes has further attempted to improve diagnostic accuracy and identify specific subgroups of patients. The main objective of this study is to provide an analysis of the literature on the role of RF isotypes in the diagnosis and prognosis of rheumatoid arthritis (RA).

METHODS

We performed a systematic literature review and meta-analysis on the role of RF isotypes in RA (only in English, from PubMed, search terms: "rheumatoid factor isotypes", "diagnosis", "prognosis" and "rheumatoid arthritis", last search 31 July 2022, two independent assessment of quality and biases, results included in tables and in the meta-analysis).

RESULTS

Thirty-six articles were examined (7517 patients). Testing all RF isotypes with latex test or nephelometry allows for the highest sensitivity (68.6%, 95% CI 66.2% to 71.0%); nonetheless, the determination of IgA isotype provides the highest specificity (91.4%, 95% CI 90.8% to 92.0%) and the highest positive likelihood ratio (7.7, 95% CI 5.7 to 10.4). When testing IgM isotype the highest diagnostic OR (21.7, 95% CI 16.1 to 29.3) is reached. When analysing anti-citrullinated protein antibodies, RF isotype determination increases diagnostic accuracy. On the other hand, these do not provide relevant prognostic information, as results are conflicting.

CONCLUSIONS

Testing RF allows the highest sensitivity, while IgA isotype the highest specificity and positive likelihood ratio for RA diagnosis. On the other hand, determination of RF isotypes dose not allow prognostic information, as data are limited and heterogeneous.

Analysis of rheumatoid factor and acute phase proteins using microarrays in patients with rheumatoid arthritis

One of the biomarkers of biggest clinical importance in rheumatoid arthritis (RA) is rheumatoid factor (IgM RF). The rheumatoid factor has insufficient sensitivity and specificity, therefore, to increase the diagnostic information of the test, acute phase proteins were used as concomitant biomarkers. Using biological microchips, we measured IgM RF, C-reactive protein (CRP) and Serum amyloid protein A (SAA) in patients with RA (n = 60), ankylosing spondylitis (AS) (n=55), systemic lupus erythematosus (SLE) (n=20) and healthy donors (HD) (n=9). It was shown that the medians of IgM RF concentrations are significantly higher (p<0.01) in patients with RA compared to patients suffering from other diseases and healthy donors. CRP and SAA were also significantly increased (p<0.05) in patients with RA and AS compared with SLE and HD. It has been shown that the complex determination of three biomarkers in differentiating RA patients with the comparison group had a higher diagnostic sensitivity than the isolated determination of IgM RF, while the addition of SAA makes the greatest contribution to improving the diagnostic characteristics of the biomarker panel: the use of a logistic regression model based on IgM RF and SAA allowed to increase the diagnostic sensitivity of the analysis from 58.3% to 65%. Thus, the developed microarray-based method can be used to detect and elucidate the diagnostic characteristics of RA biomarkers; however, further use requires validation of the obtained results on an expanded sampling.

Will 14-3-3η Be a New Diagnostic and Prognostic Biomarker in Rheumatoid Arthritis? A Prospective Study of Its Utility in Early Diagnosis and Response to Treatment

Results

Serum14-3-3η levels were significantly higher in all RA patients than in controls (P < 0.001), its sensitivity was 86.7% and 88.3% in early and established RA patients with a significant difference with RF and ACCP at early disease, and the specificity was 96.7%. There was a significant reduction of 14-3-3η levels 6 months after treatment in the first group (p=0.004), and there was a significant positive correlation between serum 14-3-3η levels and parameters of disease activity and severity.

Conclusion

14-3-3η could be a novel, potent, and efficacious diagnostic, and prognostic marker for RA with high sensitivity, that may become a new therapeutic target for RA.

Identification of a Novel Serological Marker in Seronegative Rheumatoid Arthritis Using the Peptide Library Approach

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation mainly affecting the joints leading to cartilage and bone destruction. The definition of seropositive or seronegative RA is based on the presence or absence of rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPAs). Other autoantibodies have been identified in the last decade such as antibodies directed against carbamylated antigens, peptidyl-arginine deiminase type 4 and v-Raf murine sarcoma viral oncogene homologue B. In order to identify relevant autoantigens, we screened a random peptide library (RPL) with pooled IgGs obtained from 50 patients with seronegative RA. Patients’ sera were then used in an ELISA test to identify the most frequently recognized peptide among those obtained by screening the RPL. Sera from age- and sex-matched healthy subjects were used as controls. We identified a specific peptide (RA-peptide) recognized by RA patients’ sera, but not by healthy subjects or by patients with other immune-mediated diseases. The majority of sera from seronegative and seropositive RA patients (73.8% and 63.6% respectively) contained IgG antibodies directed against the RA-peptide. Interestingly, this peptide shares homology with some self-antigens, such as Protein-tyrosine kinase 2 beta, B cell scaffold protein, Liprin-alfa1 and Cytotoxic T lymphocyte protein 4. Affinity purified anti-RA-peptide antibodies were able to cross react with these autoantigens. In conclusion, we identified a peptide that is recognized by seropositive and, most importantly, by seronegative RA patients’ sera, but not by healthy subjects, conferring to this epitope a high degree of specificity. This peptide shares also homology with other autoantigens which can be recognized by autoantibodies present in seronegative RA sera. These newly identified autoantibodies, although present also in a percentage of seropositive RA patients, may be considered as novel serum biomarkers for seronegative RA, which lacks the presence of RF and/or ACPAs.

Increased plasma levels of CCL20 in peripheral blood of rheumatoid arthritis patients and its association with clinical and laboratory parameters

INTRODUCTION

Rheumatoid arthritis (RA) is a systemic autoimmune disease that primarily affects small joints. The impaired chemokine and cytokine responses are essential pathological mechanisms for the RA clinical presentation. Given the role of chemokines and inflammatory reactions in RA pathogenesis, we evaluate the association between the plasma concentration of CCL20 with the clinical and laboratory parameters in newly diagnosed RA patients.

MATERIAL AND METHODS

Forty-five newly diagnosed RA patients and forty-five healthy subjects were enrolled in this study. The plasma levels of CCL20, rheumatoid factor, and anti-citrullinated peptide antibodies were measured using the enzyme-linked immunosorbent assay (ELISA) technique.

RESULT

The plasma levels of CCL20 were increased significantly in RA patients compared to the healthy controls (p < 0.0001). There was a positive correlation between CCL20 and RF, anti-CCP, ESR, and DAS-28 (p < 0.0001, r = 0.669; p < 0.015, r = 0.358; p < 0.0001, r = 0.586; p < 0.0001, r = 0.769).

CONCLUSION

The increased plasma levels of CCL20 in newly diagnosed RA patients may contribute to RA pathogenesis, and it is in association with clinical and laboratory parameters. Key Points • CCL20 has a contribution to the early phase of RA.

Importance of 14-3-3eta, anti-CarP, and anti-Sa in the diagnosis of seronegative rheumatoid arthritis

Background/aim

Rheumatoid arthritis (RA) is an autoimmune disease characterized by synovial inflammation. The study aimed to assess serum 14-3-3eta, anti-CarP, and anti-Sa in seronegative RA (SNRA) patients who were treatment-naïve as well as in healthy subjects. This is the first study in the literature to examine these autoantibodies together in SNRA patients.

Materials and methods

Forty-five treatment-naïve SNRA patients and 45 healthy subjects were recruited. Drugs change the levels of autoantibodies; therefore, patients who took any medication had been excluded from our study. Anti-carbamylated protein, anti-Sa, and 14-3-3eta were measured by using three different ELISA kits.

Results

Median serum concentration of healthy controls in 14-3-3eta was 0.02 (0.02–0.27) ng/mL. Median serum concentration of SNRA patients in 14-3-3eta was 1.00 (0.48–1.28) ng/mL. Data were analyzed with Mann–Whitney U tests; the P-value was <0.001 in 14-3-3eta. Receiver operating characteristic (ROC) curve analysis showed that 14-3-3eta in SNR compared to healthy controls had a significant (P < 0.001) area under the curve (AUC) of 0.90 (95% confidence interval, 0.83–0.96). At a cutoff of ≥0.33 ng/mL, the ROC curve yielded a sensitivity of 88.9%, a specificity of 82.2%, a positive predictive value of 83.3%, and a negative predictive value of 88.1%.

Conclusion

We found that 14-3-3eta can be used as a diagnostic marker in SNRA.

Combination of anti-citrullinated protein antibodies and rheumatoid factor is associated with increased systemic inflammatory mediators and more rapid progression from preclinical to clinical rheumatoid arthritis

The development of rheumatoid factor (RF) and/or anti-citrullinated protein antibodies (ACPAs) can be observed years prior to clinical diagnosis of rheumatoid arthritis (RA). Nevertheless, the interaction between these two autoantibodies and their combined effect on development of RA is unclear. We measured RF, cytokines, and ACPA subtypes in serial pre-clinical serum samples collected from 83 US veterans who all developed RA. Levels of cytokines and ACPAs were compared between the following groups: anti-cyclic citrullinated peptide (anti-CCP)-/RF- (double negative), anti-CCP+/RF-, anti-CCP-/RF+, or anti-CCP+/RF+ (double-positive). The double-positive subgroup had significantly higher levels of 20 inflammatory cytokines and 29 ACPA reactivities, and the shortest interval, 1.3 years, between the preclinical sample timepoint and diagnosis of RA. Thus, the combined presence of ACPAs and RF is associated with a more rapid progression to RA, suggesting that anti-CCP+/RF+ individuals have a more advanced preclinical disease state and that the onset of RA may be imminent.

Phenome-Wide Association Study of Rheumatoid Arthritis Subgroups Identifies Association Between Seronegative Disease and Fibromyalgia

OBJECTIVE

The differences between seronegative and seropositive rheumatoid arthritis (RA) have not been widely reported. We performed electronic health record (EHR)-based phenome-wide association studies (PheWAS) to identify disease associations in seropositive and seronegative RA.

METHODS

A validated algorithm identified RA subjects from the de-identified version of the Vanderbilt University Medical Center EHR. Serotypes were determined by rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (ACPA) values. We tested EHR-derived phenotypes using PheWAS comparing seropositive RA and seronegative RA, yielding disease associations. PheWAS was also performed in RF-positive versus RF-negative subjects and ACPA-positive versus ACPA-negative subjects. Following PheWAS, select phenotypes were then manually reviewed, and fibromyalgia was specifically evaluated using a validated algorithm.

RESULTS

A total of 2,199 RA individuals with either RF or ACPA testing were identified. Of these, 1,382 patients (63%) were classified as seropositive. Seronegative RA was associated with myalgia and myositis (odds ratio [OR] 2.1, P = 3.7 × 10^-10 ) and back pain. A manual review of the health record showed that among subjects coded for Myalgia and Myositis, ∼80% had fibromyalgia. Follow-up with a specific EHR algorithm for fibromyalgia confirmed that seronegative RA was associated with fibromyalgia (OR 1.8, P = 4.0 × 10^-6 ). Seropositive RA was associated with chronic airway obstruction (OR 2.2, P = 1.4 × 10^-4 ) and tobacco use (OR 2.2, P = 7.0 × 10^-4 ).

CONCLUSION

This PheWAS of RA patients identifies a strong association between seronegativity and fibromyalgia. It also affirms relationships between seropositivity and chronic airway obstruction and between seropositivity and tobacco use. These findings demonstrate the utility of the PheWAS approach to discover novel phenotype associations within different subgroups of a disease.

Matrix Metalloproteinases and Synovial Joint Pathology

Matrix metalloproteinases (MMPs) are zinc-dependent enzymes. These enzymes play a critical role in the destruction of articular cartilage in rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA), and the spondyloarthropathies. MMP gene expression is upregulated in these synovial joint pathologies in response to elevated levels of proinflammatory cytokines and soluble mediators such as tumor necrosis factor-α, interleukin-1 (IL-1), IL-6, IL-17, and interferon-γ. These molecules are capable of activating the mitogen-activated protein kinase and Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways by binding the cytokine to their respective receptors on immune cells, macrophages, chondrocytes, synoviocytes, and osteocytes leading to increased synthesis of MMPs. Biologic drugs and/or small-molecule inhibitors designed to block cytokine to cytokine receptor interactions or to selectively inhibit JAKs have clinical efficacy in RA, PsA, and ankylosing spondylitis which correlated with a reduction in MMPs. Although there are currently no OA-selective drugs, it is likely that such a drug would have to reduce MMP gene expression to have clinical efficacy.

Anti-CCP Antibodies and Rheumatological Findings in Brazilian Patients with Crohn's Disease

BACKGROUND/AIMS

Arthropathy is the most common extraintestinal manifestation observed in patients with Crohn's disease (CD). The present study aimed to screen rheumatoid arthritis (RA) using anti-CCP antibodies and rheumatoid factor (RF) in CD patients from Southern Brazil. Additionally, the presence of arthralgia and spondyloarthritis (SpA) was evaluated. CD patients, previously diagnosed using clinical data, imaging tests, endoscopic and histological findings, were included consecutively.

METHODS

A total of 100 patients participated in the study, of which 60% were female, with a mean age of 41.9 ± 12.04 (16-83 years). As controls, sera from 100 healthy individuals from the same geographic area were analyzed.

RESULTS

Arthralgias were present in 55% of the patients, being more frequent in women (65.5%; 36/55), than in males (34.5%). No association was found between arthralgia and the treatment method used. Six patients (6/100) had SpA previously diagnosed. In the CD group, anti-CCP was positive only in one patient, while RF was positive in 7 patients (7%; 7/100). The anti-CCP positive patient (woman, 38 years old, RF positive), fulfilled the ACR criteria and was diagnosed as RA. In the control group, anti-CCP antibodies were detected in 1% (1/100) and RF was positive in 6 of the samples (6%).

CONCLUSION

Our data showed low frequency of anti-CCP antibodies and RF in Brazilian patients with CD. Additionally, we found a high prevalence of arthralgia in these patients, with 6% of them diagnosed with SpA.

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.

Rheumatoid arthritis-celiac disease relationship: joints get that gut feeling

Rheumatoid arthritis (RA) and celiac disease (CD) belong to the autoimmune disease family. Despite being separate entities they share multiple aspects. Epidemiologically they share comparable incidence environmental influences, associated antibodies and a recent incidental surge. They differ in their HLA pre-dispositions and specific predictive and diagnostic biomarkers. At the clinical level, celiac disease exhibits extra-intestinal rheumatic manifestations and RA gastrointestinal ones. Small bowel pathology exists in rheumatic patients. A trend towards responsiveness to a gluten free diet has been observed, ameliorating celiac rheumatic manifestations, whereas dietary interventions for rheumatoid arthritis remain controversial. Pathophysiologically, both diseases are mediated by endogenous enzymes in the target organs. The infectious, dysbiotic and increased intestinal permeability theories, as drivers of the autoimmune cascade, apply to both diseases. Contrary to their specific HLA pre-disposition, the diseases share multiple non-HLA loci. Those genes are crucial for activation and regulation of adaptive and innate immunity. Recently, light was shed on the interaction between host genetics and microbiota composition in relation to CD and RA susceptibility, connecting bugs and us and autoimmunity. A better understanding of the above mentioned similarities in the gut-joint inter-relationship, may elucidate additional facets in the mosaic of autoimmunity, relating CD to RA.

Isotypes of Epstein-Barr virus antibodies in rheumatoid arthritis: association with rheumatoid factors and citrulline-dependent antibodies

In order to study the humoral immune response against Epstein-Barr virus (EBV) in patients with rheumatoid arthritis (RA) and to compare it with the two major autoantibody types in RA, plasma samples from 77 RA patients, 28 patients with systemic lupus erythematosus (SLE), and 28 healthy controls (HCs) were investigated by enzyme-linked immunosorbent assays (ELISA). Increased percentages of positives and concentrations of IgG/IgA/IgM antibodies against the latent EBV nuclear antigen-1 (EBNA-1) were observed in RA patients compared to SLE patients and HCs. Increased concentrations and percentages of positives of IgG/IgA/IgM against the early lytic EBV antigen diffuse (EAD) were also found in RA patients compared to HCs but were highest in SLE patients. Furthermore, associations between the elevated EBNA-1 IgA and EBNA-1 IgM levels and the presence of IgM and IgA rheumatoid factors (RFs) and anti-citrullinated protein antibodies (ACPAs, IgG) and between elevated IgA concentrations against EAD and the presence of RFs and ACPAs in RA patients were found. Thus, RA patients had elevated antibodies of all isotypes characteristic of latent EBV infection (whereas SLE patients had elevated antibodies characteristic of lytic EBV infection). Notably, for IgM and IgA (but not IgG), these were associated with the presence of characteristic RA autoantibodies.

Associations of rheumatoid factor and anti-citrullinated peptide antibody with disease progression and treatment outcomes in patients with rheumatoid arthritis

The objective of this study was to investigate the association of rheumatoid factor (RF) and anti-citrullinated peptide antibodies (ACPA) status with disease progression and treatment outcomes in patients with rheumatoid arthritis (RA). A total of 276 adult patients who fulfilled the American College of Rheumatology 1987 classification criteria for RA were recruited from the Rheumatology clinic, Siriraj Hospital, from January 2011 to December 2012. Demographic, clinical, and laboratory data were collected at baseline and every 3 months up to 1 year of follow-up. RF and ACPA were measured at baseline. Radiography of the hands and feet was performed at baseline and 1 year. Patients with RF+/ACPA+ had significantly more severe disease activity and impaired functional status than those who had RF-/ACPA-. Although they received more aggressive treatment with methotrexate and combination of non-biologic, disease-modifying antirheumatic drug than other groups, fewer patients in this group achieved remission at 1 year of follow-up, especially when compared to RF-/ACPA- group (12 vs. 18 %). For radiographic erosion, patients with the presence of either RF or ACPA had a higher proportion of hand erosion than seronegative patients at baseline (77, 73, 83, and 32 %, p < 0.001 for RF+/ACPA+, RF+/ACPA-, RF-/ACPA+, and RF-/ACPA-, respectively). After 1 year of follow-up, patients who developed new erosion at the hands were more prevalent in RF+/ACPA+ (32 %) and RF+/ACPA- (33 %) groups. However, "newly developed" feet erosion was most common in RF+/ACPA- group (40 %) than in other groups. Patients with positive either RF or ACPA or both have more severe and aggressive disease that requires intensive treatment to improve outcomes.

Anti-cyclic citrullinated peptide antibodies and paraoxonase-1 polymorphism in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is the most common chronic inflammatory joint disease, with a worldwide prevalence of 0.5% to 1%. Anti-cyclic citrullinated peptide antibody (anti-CCP-2 Ab) is a marker of choice for diagnosing early and late RA. Anti-oxidant enzymes activity decreases in RA patients. Till now, the relationship between the rheumatoid factor (RF) and anti-CCP-2 Ab, anti-oxidant activity and polymorphism of paraoxenase-1 (PON-1) 192 Q/R in patients with RA has not been investigated. In this study, we aimed to determine the serum level of RF and anti-CCP-2 Ab, PON-1 activity and 192 Q/R polymorphism and arylesterase (ARE) activity in patients with RA. Also, we studied RA markers in different genotypes of PON-1 of RA patients.

Methods

A total of 120 RA patients and 90 healthy persons were subjected to full clinical examinations and routine laboratory tests. PON-1 and ARE activities were determined using an enzymatic spectrophotometric method. PON-1 192 gene polymorphism was determined using polymerase chain reaction based restriction fragment analysis. RF was measured by immunoturbidimetry method and anti-CCP-2 Ab was assayed by enzyme-linked immunosorbent assay (ELISA). Statistical analysis was performed using SPSS for windows 20.0.

Results

The sensitivity and specificity of anti-CCP-2 Ab for the diagnosis of RA were 76.2% and 100% respectively. PON-1 and ARE activities were statistically lower (P <0.001) in the RA group compared to the control group. A negative correlation between RF and anti-CCP-2 Ab levels and PON-1 and ARE activities was found. No significant difference in the genotype distribution between RA patients and healthy persons was detected. RF and anti-CCP-2 Ab levels were higher in RA patients carried RR genotype than in those carried QQ genotype.

Conclusion

High RF and anti-CCP-2 antibody serum levels were found to be associated with decreased PON-1 and ARE activities with no correlation between PON-1 polymorphism and serum levels of RF and anti-CCP-2 Ab in patients with RA. These results may indicate an implication between antioxidant enzymes activity and serum levels of RF and anti-CCP-2 Ab.

Seronegative rheumatoid arthritis: pathogenetic and therapeutic aspects

Rheumatoid arthritis (RA) has long been recognised as a highly heterogeneous disease of immune dysregulation. Despite an ever-growing appreciation of the role of circulating autoantibodies in the development of 'seropositive' disease, the pathogenesis of seronegative RA remains poorly understood. Accumulating evidence suggests that RA 'serotypes', in fact, reflect distinct disease entities that, despite their clinical overlap, diverge in respect of genetic architecture, cellular pathology and even therapeutic responsiveness. Focussing on seronegative RA, this review considers these concepts and their implications for the management of patients with this challenging, though sometimes overlooked, condition.

Urinary proteome profile predictive of disease activity in rheumatoid arthritis

Current serum biomarkers for rheumatoid arthritis (RA) are not highly sensitive or specific to changes of disease activities. Thus, other complementary biomarkers have been needed to improve assessment of RA activities. In many diseases, urine has been studied as a window to provide complementary information to serum measures. Here, we conducted quantitative urinary proteome profiling using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and identified 134 differentially expressed proteins (DEPs) between RA and osteoarthritis (OA) urine samples. By integrating the DEPs with gene expression profiles in joints and mononuclear cells, we initially selected 12 biomarker candidates related to joint pathology and then tested their altered expression in independent RA and OA samples using enzyme-linked immunosorbent assay. Of the initial candidates, we selected four DEPs as final candidates that were abundant in RA patients and consistent with those observed in LC-MS/MS analysis. Among them, we further focused on urinary soluble CD14 (sCD14) and examined its diagnostic value and association with disease activity. Urinary sCD14 had a diagnostic value comparable to conventional serum measures and an even higher predictive power for disease activity when combined with serum C-reactive protein. Thus, our urinary proteome provides a diagnostic window complementary to current serum parameters for the disease activity of RA.

Association of anticyclic citrullinated peptide antibodies and/or rheumatoid factor status and clinical presentation in early arthritis: results from the ESPOIR cohort

OBJECTIVE

To compare the initial clinical, biological, and radiographic findings of early arthritis by positivity for rheumatoid factor (RF) and/or anticyclic citrullinated peptide antibodies (anti-CCP), and to validate a patient profile based on this serologic information.

METHODS

The ESPOIR cohort comprises patients presenting synovitis of at least 2 joints for 6 weeks to 6 months. Patients underwent testing for IgM rheumatoid factor (IgM-RF) and anti-CCP2 antibodies and were divided into 4 groups: RF- and anti-CCP- (group 1), RF+ and anti-CCP- (group 2), RF- and anti-CCP+ (group 3), RF+ and anti-CCP+ (group 4). We compared the groups in terms of clinical, biological, and radiographic features (baseline scores and 6-month and 12-month progression).

RESULTS

Of the 813 recruited patients, 406 (50%) were in group 1, 91 (11.2%) in group 2, 34 (4.1%) in group 3, and 281 (34.6%) in group 4. Mean baseline erythrocyte sedimentation rate and C-reactive protein were higher for anti-CCP+ groups (groups 3 and 4) than for other groups (p < 0.001), and van der Heijde-modified Sharp score for radiographs was higher for group 4 than for other groups (p < 0.001). Clinical presentation was not consistently associated with serologic profile. Radiographic progression at 1 year was higher for anti-CCP+ groups than other groups (p < 0.001).

CONCLUSION

The phenotype of patients with early arthritis with or without anti-CCP and/or RF positivity did not correspond to a particular clinical presentation. However, baseline acute-phase reactants and short-term radiographic progression were high in patients with anti-CCP positivity, which may be associated with the inflammatory process and progressive disease in patients with early arthritis.

Rheumatoid factor as a potentiator of anti-citrullinated protein antibody-mediated inflammation in rheumatoid arthritis

OBJECTIVE

The co-occurrence of rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) positivity in rheumatoid arthritis (RA) is well described. However, the mechanisms underlying the potential interaction between these 2 distinct autoantibodies have not been well defined. The aim of this study was to evaluate the epidemiologic and molecular interaction of ACPAs and RF and its association with both disease activity and measures of RA-associated inflammation.

METHODS

In a cohort of 1,488 US veterans with RA, measures of disease activity and serum levels of cytokines and multiplex ACPAs were compared between the following groups of patients: double-negative (anti-cyclic citrullinated peptide [anti-CCP]-/RF-), anti-CCP+/RF-, anti-CCP-/RF+, or double-positive (anti-CCP+/RF+). Additional studies were performed using an in vitro immune complex (IC) stimulation assay in which macrophages were incubated with ACPA ICs in the presence or absence of monoclonal IgM-RF, and tumor necrosis factor α production measured as a readout of macrophage activation.

RESULTS

Compared with the double-negative subgroup (as well as each single-positive subgroup), the double-positive subgroup exhibited higher disease activity as well as higher levels of C-reactive protein and inflammatory cytokines (all P < 0.001). In vitro stimulation of macrophages by ACPA ICs increased cytokine production, and the addition of monoclonal IgM-RF significantly increased macrophage tumor necrosis factor α production (P = 0.003 versus ACPA ICs alone).

CONCLUSION

The combined presence of ACPAs and IgM-RF mediates increased proinflammatory cytokine production in vitro and is associated with increased systemic inflammation and disease activity in RA. Our data suggest that IgM-RF enhances the capacity of ACPA ICs to stimulate macrophage cytokine production, thereby providing a mechanistic link by which RF enhances the pathogenicity of ACPA ICs in RA.

Absence of some common organ-specific and non-organ-specific autoimmunity in autoimmune polyendocrinopathy candidiasis ectodermal dystrophy

BACKGROUND

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a rare autosomal recessive disorder caused by mutations of the autoimmune regulator (AIRE) gene, whose loss of function leads to the escape of self-reactive T cells from the thymus and autoimmunity. APECED patients typically develop tissue-specific autoantibodies and anti-cytokine antibodies. Consequently, various endocrine and non-endocrine autoimmune disorders appear. However, only a certain number of autoimmune diseases develop, while some common autoimmune conditions have not been reported or are seen only anecdotally.

OBJECTIVE

We investigated the clinical manifestations and occurrence of antinuclear antibodies (AN-Abs) and antibodies against extractable nuclear antigens, citrullinated peptide, and transglutaminase in 24 patients and against bullous pemphigoid antigen 180 and desmogleins 1 (Dsg1) and Dsg3 in 30 patients of a Finnish cohort of APECED patients.

RESULTS

Despite the loss of central tolerance, the autoantibodies investigated were not overrepresented among the APECED patients. None of the patients had a history of autoimmune connective tissue disease, rheumatoid arthritis, celiac disease, or autoimmune cutaneous bullous disorders. Altogether, 25% (6/24) had low-titer (1:80) AN-Abs. Two patients had anti-BP180 antibodies and two others had anti-Dsg3 antibodies without any cutaneous or mucosal symptoms. No anti-citrullinated peptide and anti-transglutaminase reactivity was found.

CONCLUSIONS

The mechanisms that drives tolerance to tissue autoantigens is not fully understood as even APECED patients, who are genetically prone to develop autoantibodies, are tolerant against some common autoantigens. The hypothesis that some of the anti-cytokine antibodies commonly found in APECED patients may be protective should be investigated in larger series.

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.

The association of anti-CCP1 antibodies with disease activity score 28 (DAS-28) in rheumatoid arthritis

Background:

Rheumatoid arthritis (RA) is one of the most frequent autoimmune diseases in the world which affect about 1% of people. Measurement of the anti-CCP1 antibody titer in these patients is one of the new tests that is available in our country and in the multiple studies has been shown to be more specific than rheumatoid factor in the diagnosis of RA (97%). This test becomes positive in early stage of disease and it has a high predictive value. The aim of our study was to determine the relationship between anti-CCP1 antibody and disease activity score 28 (DAS-28) in patients with rheumatoid arthritis.

Materials and Methods:

A cross-sectional study was performed in 90 patients with RA for evaluating the relation between anti-CCP1 antibody titer and DAS-28, patients were selected by consecutive method; serum samples were collected from patients. Anti-CCP1 antibody was measured by the corresponding enzyme-linked immunosorbent assay. Additionally, erythrocyte sedimentation rates (ESR), rheumatoid factor (RF), DAS-28, visual analog scale (VAS) were determined in patients with RA. Statistical analysis performed with t-test and Pearson's correlations coefficient.

Results:

Anti-CCP1 level was associated with DAS-28 (P<0.001, r=0.35). The largest linear correlation was between anti-CCP1 antibody levels and VAS; it means that higher titers of anti-CCP1 antibody are associated with more painful joints in our patients. The average of DAS-28 in our positive and negative anti-CCP1 antibody patients was 5.07±1.1 and 3.5±1.5, respectively (P<0.05).

Conclusion:

There was moderate correlation between anti-CCP1 titer and DAS-28.

The reporting quality of studies investigating the diagnostic accuracy of anti-CCP antibody in rheumatoid arthritis and its impact on diagnostic estimates

BACKGROUND

Recently anti-CCP testing has become popular in the diagnosis of rheumatoid arthritis (RA). However, the inadequate reporting of the relevant diagnostic studies may overestimate and bias the results, directing scientists into making false decisions. The aim of the present study was to evaluate the reporting quality of studies used anti-CCP2 for the diagnosis of RA and to explore the impact of reporting quality on pooled estimates of diagnostic measures.

METHODS

PubMed was searched for clinical studies investigated the diagnostic accuracy of anti-CCP. The studies were evaluated for their reporting quality according to STARD statement. The overall reporting quality and the differences between high and low quality studies were explored. The effect of reporting quality on pooled estimates of diagnostic accuracy was also examined.

RESULTS

The overall reporting quality was relatively good but there are some essential methodological aspects of the studies that are seldom reported making the assessment of study validity difficult. Comparing the quality of reporting in high versus low quality articles, significant differences were seen in a relatively large number of methodological items. Overall, the STARD score (high/low) has no effect on the pooled sensitivities and specificities. However, the reporting of specific STARD items (e.g. reporting sufficiently the methods used in calculating the measures of diagnostic accuracy and reporting of demographic and clinical characteristics/features of the study population) has an effect on sensitivity and specificity.

CONCLUSIONS

The reporting quality of the diagnostic studies needs further improvement since the study quality may bias the estimates of diagnostic accuracy.

A comparative study on the diversity of clinical features between the sero-negative and sero-positive rheumatoid arthritis patients

To investigate the similarities and differences in clinical features between the sero-negative and sero-positive rheumatoid arthritis (RA) patients. Two hundred and sixty-two RA patients who fulfilled the 1987 ACR RA Classification Criteria were enrolled into this study. They were divided into sero-negative and sero-positive group depending on the presence or absence of rheumatoid factor (RF) and anti-cyclic citrullinate peptide (anti-CCP). The clinical features were compared between these two groups. Forty-six (17.6%) RA patients were classified as sero-negative group. The disease onset of sero-negative RA patients was later than that of sero-positive RA patients (52.4 ± 15.9 vs. 47.4 ± 15.5 years, P < 0.05). At the end of the first 2 years after disease onset, bone erosion shown in the hand X-ray occurred in 4 out of 24 (16.7%) patients with sero-negative RA. However, only 5.2% (5/97) patients with sero-positive RA developed bone erosion (P < 0.05). In the sero-positive RA patients, the titer of RF was correlated with swollen joint counts (SJC), tender joint counts (TJC), erythrocyte sedimentation rate (ESR), and disease activity score in 28 joints (DAS28) (P < 0.05), but anti-CCP was not. Sero-negative and sero-positive RA are probably two distinct disease subtypes driven by different mechanisms.

Second generation automated anti-CCP test better predicts the clinical diagnosis of rheumatoid arthritis

Rheumatoid arthritis (RA) is one of the most common systemic autoimmune diseases. The presence of antibodies to cyclic citrullinated peptide (CCP) is better at discriminating RA patients and is also associated with significantly more disease activity compared to serum rheumatoid factor. In this study, we assessed two new automated second generation tests to detect the presence of anti-CCP antibodies in 226 serum samples submitted to the Clinical Immunology Laboratory for anti-CCP antibody testing. We compared CCP antibody results on these samples obtained using the ImmunoCAP 250 (Phadia) and the Architect i2000SR (Abbott Laboratories) instruments to our currently used CCP IgG third generation manual ELISA (Inova Diagnostics). One hundred and fifty-four samples were negative while 52 were positive by all three tests. Eighteen samples were negative by the automated tests but weakly/moderately positive by manual ELISA yielding an overall concordance of 79%. When we compared the discordant test results to patient diagnosis, we observed a better correlation with clinical RA diagnosis for the new automated tests compared to the manual ELISA. These two new anti-CCP antibody tests have the benefit of automation and may have better positive predictive value for the diagnosis of RA than our current manual ELISA.

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.

Aberrant IgG galactosylation precedes disease onset, correlates with disease activity, and is prevalent in autoantibodies in rheumatoid arthritis

OBJECTIVE

To examine the association between aberrant IgG galactosylation and disease parameters in rheumatoid arthritis (RA).

METHODS

Analysis of N-glycan in serum samples from multiple cohorts was performed. The IgG N-glycan content and the timing of N-glycan aberrancy relative to disease onset were compared in healthy subjects and in patients with RA. Correlations between aberrant galactosylation and disease activity were assessed in the RA cohorts. The impact of disease activity, sex, age, anti-cyclic citrullinated peptide (anti-CCP) antibody titer, disease duration, and C-reactive protein level on aberrant galactosylation was determined using multivariate analysis. The N-glycan content was also compared between epitope affinity-purified autoantibodies and the remaining IgG repertoire in RA patients.

RESULTS

Our results confirm the aberrant galactosylation of IgG in RA patients as compared with healthy controls (mean +/- SD 1.36 +/- 0.43 versus 1.01 +/- 0.23; P < 0.0001). We observed a significant correlation between levels of aberrant IgG galactosylation and disease activity (Spearman's rho = 0.37, P < 0.0001). This correlation was higher in women (Spearman's rho = 0.60, P < 0.0001) than in men (Spearman's rho = 0.16, P = 0.10). Further, aberrant IgG galactosylation substantially predated the onset of arthritis and the diagnosis of RA (3.5 years) and resided selectively in the anticitrullinated antigen fraction.

CONCLUSION

Our findings identify aberrant IgG galactosylation as a dysregulated component of the humoral immune response in RA that begins prior to disease onset, associates with disease activity in a sex-specific manner, and resides preferentially in autoantibodies.

Antibodies to mutated citrullinated vimentin in rheumatoid arthritis: diagnostic value, association with radiological damage and axial skeleton affection

Background:

Early definitive diagnosis and effective treatment are mandatory in rheumatoid arthritis (RA) as it can halt the disease progression and subsequent joints destruction.

Objective:

To investigate the diagnostic and prognostic value of anti-mutated citrullinated vimentin (anti-MCV) and its correlation with disease activity, peripheral and axial skeleton affection in RA patients.

Patients and methods:

A total of 123 patients with different rheumatic diseases were enrolled in a prospective-two year study at Ain Shams University hospital: 64 patients with RA and 59 patients with other rheumatic diseases as controls. RA patients were fulfilling the traditional and the new ACR/EULAR diagnostic criteria for RA. They have been followed up for two years. At baseline, all RA patients were subjected to: Clinical assessment of disease activity by taking full histories, general and local examination, measurement of 28 joint count of tender and swollen joints with calculation of disease activity score (DAS-28) for each patient. Complete blood count, erythrocytes sedimentation rate, C-reactive protein and rheumatoid factor titers were performed. Anti-MCV IgG immunoglobulins’ assay was performed at the study endpoint by ELISA. RA patients were then classified into; anti-MCV positive and anti-MCV negative groups for statistical comparison. Plain X-ray was performed on the peripheral joints and scored by the Simple Erosion Narrowing score (SEN-score). Magnetic Resonance Imaging (MRI) scans were carried out to 22 RA patients on cervical and lumbosacral regions.

Results:

Anti-MCV antibodies were found to be of high sensitivity (79.6%) and specificity (96.6%) in diagnosing RA. The area under the curve was 0.893 at 95% confidence interval (CI), confers an odds ratio of 23.5. Anti-MCV positive RA patients had significantly higher DAS-28 and SEN-scores than anti-MCV negative patients; who were found to have more benign disease with lower incidence of erosions (P < 0.05). MRI scans revealed that; 17/22 (77%) had cervical joints involvement while, 8 (36%) had lumbo-sacral joint lesions (P < 0.05), both were correlated significantly with aggressive peripheral joint disease.

Conclusion:

Anti-MCV antibodies are promising diagnostic and prognostic marker in RA, with high sensitivity and specificity. They may identify a subset of RA patients with aggressive early erosive disease. The axial skeleton—especially the cervical spine—could be affected in RA and this was correlated with aggressive peripheral joints’ disease. MRI scanning is a sensitive method for detecting axial skeleton involvement in RA, in attempt for better disease control and outcomes.

Anti-citrullinated peptide antibody assays and their role in the diagnosis of rheumatoid arthritis

Increasingly, assays for the detection of anti-citrullinated peptide antibodies (ACPA) are used in RA diagnosis. This review summarizes the biologic basis and development of ACPA assays, available ACPA assays and their performance characteristics, and diagnostic properties of ACPA alone and compared to rheumatoid factor (RF) in early RA. We also review correlations, precision, costs and cost-effectiveness, availability, stability and reproducibility of the available assays. Taken together, data indicate that ACPA has a higher specificity than RF for early RA, good predictive validity, high sensitivity, apparent cost-effectiveness and good stability and reproducibility. Given its superior performance characteristics and increasing availability, ACPA is emerging as the most useful single assay for the diagnosis of RA.

Diagnostic accuracy of immunoassays for the detection of antibodies to citrullinated proteins

Anticitrullinated protein/peptide antibodies (ACPA) are highly specific for rheumatoid arthritis (RA). They can be found early in the disease course and are associated with more severe joint destruction and disease activity. In the last 4 years, important progress has been made in the detection and identification of ACPA, improving antigenic composition and epitope recognition. Consequently, many ACPA-ELISA kits have been developed by several manufacturers and are now commercially available. However, albeit their widespread use in clinical laboratories, the use of some kits has not been accompanied by a clinical validation nor by a comparative evaluation of their diagnostic accuracy. In addition, full automation of ACPA assays featuring ease of use, rapid response, and high productivity is just beginning to appear on the market and also deserves clinical and analytical validation. This review will consider the most relevant characteristics of the ACPA-ELISA assays and will describe the results of a comparative study performed with all the currently available second- and third-generation commercial methods.

Diagnostic and prognostic value of antibodies against chimeric fibrin/filaggrin citrullinated synthetic peptides in rheumatoid arthritis

INTRODUCTION

Evidence suggests that citrullinated fibrin(ogen) may be a potential in vivo target of anticitrullinated protein/peptide antibodies (ACPA) in rheumatoid arthritis (RA). We compared the diagnostic yield of three enzyme-linked immunosorbent assay (ELISA) tests by using chimeric fibrin/filaggrin citrullinated synthetic peptides (CFFCP1, CFFCP2, CFFCP3) with a commercial CCP2-based test in RA and analyzed their prognostic values in early RA.

METHODS

Samples from 307 blood donors and patients with RA (322), psoriatic arthritis (133), systemic lupus erythematosus (119), and hepatitis C infection (84) were assayed by using CFFCP- and CCP2-based tests. Autoantibodies also were analyzed at baseline and during a 2-year follow-up in 98 early RA patients to determine their prognostic value.

RESULTS

With cutoffs giving 98% specificity for RA versus blood donors, the sensitivity was 72.1% for CFFCP1, 78.0% for CFFCP2, 71.4% for CFFCP3, and 73.9% for CCP2, with positive predictive values greater than 97% in all cases. CFFCP sensitivity in RA increased to 80.4% without losing specificity when positivity was considered as any positive anti-CFFCP status. Specificity of the three CFFCP tests versus other rheumatic populations was high (> 90%) and similar to those for the CCP2. In early RA, CFFCP1 best identified patients with a poor radiographic outcome. Radiographic progression was faster in the small subgroup of CCP2-negative and CFFCP1-positive patients than in those negative for both autoantibodies. CFFCP antibodies decreased after 1 year, but without any correlation with changes in disease activity.

CONCLUSIONS

CFFCP-based assays are highly sensitive and specific for RA. Early RA patients with anti-CFFCP1 antibodies, including CCP2-negative patients, show greater radiographic progression.

[Diagnostic utility of anti-cyclic citrullinated peptide antibody in early rheumatoid arthritis]

Current therapeutic strategies against rheumatoid arthritis (RA) employ increasingly aggressive regimens from an early stage of the disease ; thus, serological markers more specific than IgM-rheumatoid factor (IgM-RF) are desirable. Anti-cyclic citrullinated peptide (anti-CCP) antibody has been reported as a useful and highly specificity marker for the diagnosis of RA. To clarify the diagnostic utility of anti-CCP antibody in early RA, we measured serum concentrations of anti-CCP antibody, IgM-RF, anti-agalactosyl IgG antibody and matrix metalloproteinase (MMP)-3 in 184 polyarthritis patients who showed onset symptoms within the previous 2 years. The diagnostic sensitivity of anti-CCP antibody in early RA was 60.0%, equivalent to IgM-RF (66.3%) and anti-agalactosyl IgG antibody (66.0%). Specificity, positive predictive values and diagnostic accuracy of anti-CCP antibody were the best among the four tested makers. In 38 patients who initially did not meet the ACR criteria for RA, but were diagnosed with RA during the course, the diagnostic sensitivity of anti-CCP antibody was 55.3%. On the other hand, the disease activity score (DAS) 28 of anti-CCP antibody positive and the negative patients was 5.16 and 5.34, respectively. Our data indicated that determination of anti-CCP antibody was useful for early diagnosis of RA.

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

INTRODUCTION

The aim of our study was to investigate the association between arthritic disease activity and antibodies to mutated citrullinated vimentin (anti-MCV), because such a relation has been suggested.

METHODS

Anti-MCV levels were measured in 162 patients with early arthritis (123 with rheumatoid arthritis and 39 with undifferentiated arthritis) at baseline and at 1 and 2 years of follow up. Disease activity was measured using the disease activity score (Disease Activity Score based on 28 joints [DAS28]) and serum C-reactive protein. General estimation equation analysis was used to assess the relation between anti-MCV levels and DAS28 over time.

RESULTS

Both, anti-MCV levels and DAS28 exhibited a significant decrease during the first and second year. However, the association between anti-MCV levels and DAS28, adjusted for dependency on sequential measurements within one individual, was very low (beta = 0.00075). In a population of patients with rheumatoid arthritis or undifferentiated arthritis, anti-MCV had a specificity of 92.3% and a sensitivity of 59.3% when using the recommended cut-off of 20 U/ml. Specificity and sensitivity of antibodies against second-generation cyclic citrullinated peptide, using the recommended cut-off value of 25 U/ml, were 92.1% and 55.3%, respectively. Anti-MCV-positive early arthritis patients had significantly higher Sharp-van der Heijde score, erythrocyte sedimentation rate and C-reactive protein levels than did anti-MCV-negative patients at all time points (P < 0.005), but DAS28 was higher in anti-MCV-positive patients at 2 years of follow up only (P < 0.05).

CONCLUSION

Because the correlation between anti-MCV levels and parameters of disease activity was very low, we conclude that it is not useful to monitor disease activity with anti-MCV levels.

Mutation and citrullination modifies vimentin to a novel autoantigen for rheumatoid arthritis

OBJECTIVE

Modification of antigens represents a trigger for the generation of autoantibodies. In the pathogenesis of rheumatoid arthritis (RA), citrullination of proteins has been shown to be a critical process, and the determination of antibodies against citrullinated antigens has been a diagnostic milestone. We undertook this study to determine whether antibodies to mutated and citrullinated vimentin (MCV) could serve as a diagnostic and prognostic marker for RA.

METHODS

We identified novel isoforms of human MCV in the synovial fluid of RA patients. The significance of these disease-related modifications was investigated by the analysis of autoantibody reactivities. In a group of 1,151 RA patients, the diagnostic significance and the prognostic value of an anti-MCV enzyme-linked immunosorbent assay (ELISA) were compared with that of an anti-cyclic citrullinated peptide (anti-CCP) ELISA.

RESULTS

In RA, sensitivities of 82% and 72% were calculated for the anti-MCV and anti-CCP assays, respectively. The specificity of both assays was comparable (98% and 96%, respectively). In followup analyses of 16 RA patients with moderate disease activity (mean Disease Activity Score in 28 joints [DAS28] of 2.72) and 26 RA patients with active disease (mean DAS28 of 5.07), disease stratification of RA was possible using the anti-MCV assay (P = 0.0084). A significant correlation of anti-MCV antibodies with the DAS28 was documented (r = 0.5334, P = 0.0003), in 42 RA patients (n = 427 antibody determinations at different time points).

CONCLUSION

Antigenic properties of vimentin were determined by mutation and citrullination. Anti-MCV antibodies are a novel diagnostic marker for RA. Furthermore, they may allow monitoring and-if confirmed in even larger series of patients-stratification of disease.

Analytical and diagnostic characteristics of 11 2nd- and 3rd-generation immunoenzymatic methods for the detection of antibodies to citrullinated proteins

BACKGROUND

Measurement of antibodies to citrullinated peptides or proteins (CP) is a new test for the diagnosis of rheumatoid arthritis (RA). We analyzed the analytical characteristics and diagnostic accuracy of commercially available methods.

METHODS

We studied 11 commercially available 2nd- and 3rd-generation methods that used various citrullinated antigen substrates: synthetic cyclic peptides, recombinant rat filaggrin, mutated human vimentin, and Epstein-Barr virus- or IgG-derived peptides. We assessed imprecision by measuring samples with low, intermediate, and high concentrations 5 times on each of 5 days. We measured CPs by each of the assays in 100 serum samples from patients with RA and in 202 samples from healthy persons or patients with other autoimmune, viral, or neoplastic diseases.

RESULTS

The between-run imprecision (CV) of the methods was between 0.4% and 22%, and the repeatability (within-run imprecision) was 0.5%-19%. The areas under the ROC curves varied between 0.79 (95% CI, 0.72-0.85) and 0.92 (0.88-0.95). At a fixed specificity of 98.5%, the sensitivities ranged from 41% (95% CI, 31%-51%) to 74% (64%-82%). Sensitivities and specificities varied markedly at the manufacturer's suggested cutoffs. Most false-positive results were recorded in patients with viral infections. The methods that use the original synthetic cyclic CP gave the best and very similar performances, although these methods use different components in their reagent sets (conjugate, type of substrate, dilution, and washing buffers). This finding shows that the antigenic source is the most important variable in determining the diagnostic accuracy of the methods.

CONCLUSIONS

The analytical imprecision and diagnostic accuracies of commercially available methods for the detection of anti-CP antibodies differ. Careful selection of methods is needed.

Cartilage Oligomeric Matrix Protein Level in Rheumatic Diseases: Potential Use as a Marker for Measuring Articular Cartilage Damage and/or the Therapeutic Efficacy of Treatments

Cartilage oligomeric matrix protein (COMP) is a tissue-specific noncollagenous protein that was first detected in the serum and the synovial fluid of patients suffering from rheumatic disorders, such as rheumatoid arthritis, reactive arthritis, juvenile chronic arthritis, and osteoarthritis. In this review, the authors consider serum COMP levels in different diseases and discuss their study of patients with rheumatoid arthritis treated with anti-TNF-alpha, to evaluate whether COMP is able to predict a rapid and sustained clinical response to these drugs. They observe that patients with high COMP levels have a lower ACR 70 response independently of the state of systemic inflammation, and conclude that COMP seems to have a pathogenetic role that is independent of the mechanisms regulating inflammatory processes.

Outcomes in rheumatoid arthritis: incorporating the patient perspective

PURPOSE OF REVIEW

As biologics have improved the prognosis for rheumatoid arthritis, the prioritization of outcomes has shifted. Methods of quantifying concerns of particular importance to patients as a basis for better addressing the patient perspective in treatment are being developed. This review aims first to highlight some of the recent research in more traditional outcomes and then to focus on the rapid development of patient-centered outcomes over the last several years.

RECENT FINDINGS

Clinical trials with combinations of biologics and other disease-modifying antirheumatic drugs have reported significant improvement in radiographs, inflammatory markers and joint exams in rheumatoid arthritis patients. Concomitantly, several studies have appeared in major journals, reporting that patients are emphasizing outcomes such as fatigue, return to normalcy and mental health that are less easily measured by the traditional outcomes markers.

SUMMARY

Recent studies have shown both that rheumatologist and patient approaches to achieving wellness differ and providing patients with a sense of control in reaching that state of wellness leads to better outcomes. Current research is focused on evaluating how best to measure the patient assessments and incorporate the patient voice into the clinic.

The immune response to citrullinated proteins in patients with rheumatoid arthritis

This article reviews data concerning the applicability of anti-citrullinated peptide antibodies in the diagnosis, estimation of prognosis, and follow-up of patients with rheumatoid arthritis (RA). The production of anti-citrullinated peptide antibodies is closely associated with the presence of the HLA-DRB1 shared epitope, a known risk factor for development of RA, and the production may be influenced by environmental factors such as tobacco smoking. Patients who harbor this antibody from the early stage of their disease develop more severe erosive disease than patients with RA who lack the antibody. The anti-citrullinated peptide antibody level may be a reflection of disease activity, at least in the early phase of the disease. The antibody can sometimes be found several years before the onset of clinical symptoms of RA, which may represent an open window for preventive measures to be taken.