The relationship between the presence of anti-cyclic citrullinated peptide antibodies and clinical phenotype in very early rheumatoid arthritis

The first involved joints and associated factors in patients with rheumatoid arthritis

Objectives

This study aimed to investigate the first involved joints and associated factors in Turkish patients with rheumatoid arthritis (RA).

Patients and methods

This retrospective cross-sectional study included 300 newly diagnosed and disease-modifying antirheumatic drug-naïve RA patients (240 females, 60 males; mean age: 54±1.2 years; range, 18 to 82 years). Baseline demographic, clinical, and laboratory data were evaluated between January 2022 and December 2022. The patients were divided into four groups according to autoantibody profile: antibody-negative patients (Group 1; both RF and anti-CCP were negative in this group of patients), RF-positive patients (Group 2), anti-CCP-positive patients (Group 3), and patients with dual seropositivity with RF and antiCCP (Group 4). The patients were also divided into two groups according to the size of the first affected joint: patients with SJI at diagnosis and patients without SJI involvement at diagnosis.

Results

Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibody positivity rates were 40.3% and 35.6%, respectively. The mean lag time to diagnosis was 25±36 months. At the disease onset, 20% of patients did not have small joint involvement (SJI). Seronegative patients tended to be female (p=0.001), had longer lag time (p=0.001), and had lower levels of C-reactive protein (p=0.025), white blood count (p=0.005), and neutrophil/lymphocyte ratio (p=0.001) compared to the dual seropositive group. Patients presenting with SJI had a younger age (p=0.002), tended to be female (p=0.001), and had lower RF (p=0.034) and anti-CCP (p=0.031) positivity. Only age (p=0.005) and dual seronegativity (RF and anti-CCP; p=0.035) were the independent predictors of SJI in multivariate analysis.

Conclusion

The decreasing age and seronegative status were defined as independent risk factors of SJI at the onset of RA. Population-based, prospective studies are needed for earlier diagnosis.

Pathophysiology and stratification of treatment-resistant rheumatoid arthritis

Early diagnosis and timely therapeutic intervention are clinical challenges of rheumatoid arthritis (RA), especially for treatment-resistant or difficult-to-treat patients. Little is known about the immunological mechanisms involved in refractory RA. In this review, we summarize previous research findings on the immunological mechanisms of treatment-resistant RA. Genetic prediction of treatment-resistant RA is challenging. Patients with and without anti-cyclic citrullinated peptide autoantibodies are considered part of distinct subgroups, especially regarding long-term clinical prognosis and treatment responses. B cells, T cells and other immune cells and fibroblasts are of pathophysiological importance and are associated with treatment responses. Finally, we propose a new hypothesis that stratifies patients with RA into two subgroups with distinct immunological pathologies based on our recent immunomics analysis of RA. One RA subgroup with a favorable prognosis is characterized by increased interferon signaling. Another subgroup with a worse prognosis is characterized by enhanced acquired immune responses. Increases in dendritic cell precursors and diversified autoreactive anti-modified protein antibodies may have pathophysiological roles, especially in the latter subgroup. These findings that improve treatment response predictions might contribute to future precision medicine for RA.

Aberrant B cell receptor signaling in circulating naïve and IgA+ memory B cells from newly-diagnosed autoantibody-positive rheumatoid arthritis patients

OBJECTIVE

Altered B cell receptor (BCR) signaling has been implicated in the pathogenesis of rheumatoid arthritis (RA). Here we aimed to identify signaling aberrations in autoantibody-positive and autoantibody-negative RA patients by performing a comprehensive analysis of the BCR signaling cascade in different B cell subsets.

METHODS

We first optimized phosphoflow cytometry for an in-depth analysis of BCR signaling across immunoglobulin isotypes in healthy donors. Subsequently, we compared BCR signaling in circulating B cell subsets from treatment-naïve, newly-diagnosed autoantibody-positive RA and autoantibody-negative RA patients and healthy controls (HCs).

RESULTS

We observed subset-specific phosphorylation patterns of the BCR signalosome in circulating B cells from healthy donors. Compared with HCs, autoantibody-positive RA patients displayed enhanced responses to BCR stimulation for multiple signaling proteins, specifically in naïve and IgA+ memory B cells. Whereas in unstimulated healthy donor B cells, the phosphorylation status of individual signaling proteins showed only limited correlation, BCR stimulation enhanced the interconnectivity in phosphorylation within the BCR signalosome. However, this strong interconnectivity within the BCR signalosome in stimulated B cells from HCs was lost in RA, especially in autoantibody-positive RA patients. Finally, we observed strong correlations between SYK and BTK protein expression, and IgA and IgG anti-citrullinated protein antibody concentrations in serum from autoantibody-positive RA patients.

CONCLUSION

Collectively, the isotype-specific analysis of multiple key components of the BCR signalosome identified aberrant BCR signaling responses in treatment-naïve autoantibody-positive RA patients, particularly in naïve B cells and IgA+ memory B cells. Our findings support differential involvement of dysregulated BCR signaling in the pathogenesis of autoantibody-positive and autoantibody-negative RA.

The Symptoms in Persons At Risk of Rheumatoid Arthritis (SPARRA) questionnaire: predicting clinical arthritis development

OBJECTIVE

There is a need to better define symptom characteristics associated with arthritis development in individuals at risk of rheumatoid arthritis (RA). We investigated whether reported symptoms in at-risk individuals could predict arthritis development and whether predictive symptoms differed between seropositive and seronegative at-risk individuals.

METHOD

At-risk individuals from four cohorts (Netherlands, UK, Sweden, and Switzerland) completed the Symptoms in Persons At Risk of Rheumatoid Arthritis (SPARRA) questionnaire. Participants had either (i) anti-citrullinated protein antibodies and/or rheumatoid factor, or (ii) relevant symptoms with or without RA antibodies. Follow up was ≥ 24 months or until clinical arthritis development. Stepwise forward selection created SPARRA prediction models for the combined group and for a seropositive subgroup.

RESULTS

Of 214 participants, the mean age was 50 years, 67% were female, and 27% (n = 58) developed clinical arthritis after a median time of 7 months. Four symptoms predicted arthritis development: self-reported joint swelling, joint pain moving from side to side (combined group only), feeling pins and needles in the joints, and often feeling fatigued (predicting non-arthritis).

CONCLUSION

Specific symptoms can provide useful information to estimate a person's RA risk. Differences in predictive symptoms between seropositive and seronegative at-risk individuals need to be further investigated. Future research is needed to determine whether changes in symptoms over time improve prediction and to determine the value of SPARRA in optimizing the selection of individuals who need to consult a rheumatologist.

Immunomics analysis of rheumatoid arthritis identified precursor dendritic cells as a key cell subset of treatment resistance

OBJECTIVES

Little is known about the immunology underlying variable treatment response in rheumatoid arthritis (RA). We performed large-scale transcriptome analyses of peripheral blood immune cell subsets to identify immune cells that predict treatment resistance.

METHODS

We isolated 18 peripheral blood immune cell subsets of 55 patients with RA requiring addition of new treatment and 39 healthy controls, and performed RNA sequencing. Transcriptome changes in RA and treatment effects were systematically characterised. Association between immune cell gene modules and treatment resistance was evaluated. We validated predictive value of identified parameters for treatment resistance using quantitative PCR (qPCR) and mass cytometric analysis cohorts. We also characterised the identified population by synovial single cell RNA-sequencing analysis.

RESULTS

Immune cells of patients with RA were characterised by enhanced interferon and IL6-JAK-STAT3 signalling that demonstrate partial normalisation after treatment. A gene expression module of plasmacytoid dendritic cells (pDC) reflecting the expansion of dendritic cell precursors (pre-DC) exhibited strongest association with treatment resistance. Type I interferon signalling was negatively correlated to pre-DC gene expression. qPCR and mass cytometric analysis in independent cohorts validated that the pre-DC associated gene expression and the proportion of pre-DC were significantly higher before treatment in treatment-resistant patients. A cluster of synovial DCs showed both features of pre-DC and pro-inflammatory conventional DC2s.

CONCLUSIONS

An increase in pre-DC in peripheral blood predicted RA treatment resistance. Pre-DC could have pathophysiological relevance to RA treatment response.

Sustained DMARD-free remission in rheumatoid arthritis - about concepts and moving towards practice

Sustained DMARD-free remission (SDFR) is the best possible outcome in RA. It is characterized by sustained absence of clinical arthritis, which is accompanied by resolution of symptoms and restoration of normal physical functioning. Therefore it's the best proxy for cure in RA. The mechanisms underlying SDFR-development are yet unidentified. Hypothetically, there are two possible scenarios. The first hypothesis is based on the concept of regaining immune-tolerance, which implies that RA-patients are similar at diagnosis and that disease-processes during the disease-course shift into a favorable direction, resulting in regaining a state in which arthritis is persistently absent. This could imply that SDFR is theoretically achievable for all RA-patients. The alternative hypothesis is that RA-patients who achieve SDFR are intrinsically different from those who cannot. This would imply that DMARD-cessation could be restricted to a subgroup of RA-patients. Since the 1990s, DMARD-discontinuation and SDFR have been increasingly studied as long-term-outcome in RA. In this review, we describe hitherto results of clinical, genetic, serological, histological and imaging studies and looked for arguments for the first or second hypothesis in both auto-antibody-positive and auto-antibody-negative RA. In auto-antibody-negative RA, SDFR is presumably restricted to a subgroup of patients with high serological-markers of inflammation at diagnosis and a rapid and sustained decrease in inflammation after treatment-start. Identifying these RA-patients could be helpful in realizing personalized-medicine. In auto-antibody-positive RA, only few patients achieve SDFR and no definite conclusions can be drawn, but data could suggest that SDFR-patients might be a subgroup with relatively low inflammation from disease-presentation onwards.

The current status of anti-citrullinated protein antibodies and citrullinated protein-reactive B cells in the pathogenesis of rheumatoid arthritis

Anti-citrullinated protein antibodies are a hallmark of rheumatoid arthritis. It is widely acknowledged that the presence of ACPAs is the result of the interaction of genes, the environment and epigenetic modifications. The mechanism by which the factors, especially citrullination and ACPA glycosylation, affect ACPAs is still unclear. In this article, we review the presence of the ACPAs in RA and their relationship with clinical manifestations. The pathogenicity of ACPAs and B cells in RA was also summarized. A growing body of evidence has shown that ACPA-positive patients have more serious bone erosion and destruction and poor clinical prognosis than ACPA-negative patients. Recently, with the direct study of citrullinated protein-reactive B cells, their role in the development of rheumatoid arthritis has been further understood. It indicates that further understanding of the mechanism of ACPAs and CP-reactive B cells would beneficial in the prevention and treatment of RA.

Persistent inflammatory and non-inflammatory mechanisms in refractory rheumatoid arthritis

Despite nearly three decades of advances in the management of rheumatoid arthritis (RA), a substantial minority of patients are exposed to multiple DMARDs without necessarily benefitting from them; a group of patients variously designated as having 'difficult to treat', 'treatment-resistant' or 'refractory' RA. This Review of refractory RA focuses on two types of patients: those for whom multiple targeted therapies lack efficacy and who have persistent inflammatory pathology, which we designate as persistent inflammatory refractory RA (PIRRA); and those with supposed refractory RA who have continued disease activity that is predominantly independent of objective evidence of inflammation, which we designate as non-inflammatory refractory RA (NIRRA). These two types of disease are not mutually exclusive, but identifying those individuals with predominant PIRRA or NIRRA is important, as it informs distinct treatment and management approaches. This Review outlines the clinical differences between PIRRA and NIRRA, the genetic and epigenetic mechanisms and immune pathways that might contribute to the immunopathogenesis of recalcitrant synovitis in PIRRA, and a possible basis for non-inflammatory symptomatology in NIRRA. Future approaches towards the definition of refractory RA and the application of single-cell and integrated omics technologies to the identification of refractory RA endotypes are also discussed.

Enhanced treatment strategies and distinct disease outcomes among autoantibody-positive and -negative rheumatoid arthritis patients over 25 years: A longitudinal cohort study in the Netherlands

BACKGROUND

Based on different genetic and environmental risk factors and histology, it has been proposed that rheumatoid arthritis (RA) consists of 2 types: autoantibody-positive and autoantibody-negative RA. However, until now, this remained hypothetical. To assess this hypothesis, we studied whether the long-term outcomes differed for these 2 groups of RA patients.

METHODS AND FINDINGS

In the Leiden Early Arthritis Clinic cohort, 1,285 consecutive RA patients were included between 1993 and 2016 and followed yearly. Treatment protocols in routine care improved over time, irrespective of autoantibody status, and 5 inclusion periods were used as instrumental variables: 1993-1996, delayed mild disease-modifying antirheumatic drug (DMARD) initiation (reference period); 1997-2000, early mild DMARDs; 2001-2005, early methotrexate; 2006-2010, early methotrexate followed by treat-to-target adjustments; 2011-2016, similar to 2006-2010 plus additional efforts for very early referral. Three long-term outcomes were studied: sustained DMARD-free remission (SDFR) (persistent absence of clinical synovitis after DMARD cessation), mortality, and functional disability measured by yearly Health Assessment Questionnaire (HAQ). Treatment response in the short term (disease activity) was measured by Disease Activity Score-28 with erythrocyte sedimentation rate (DAS28-ESR). Linear mixed models and Cox regression were used, stratified for autoantibody positivity, defined as IgG anti-CCP2 and/or IgM rheumatoid factor positivity. In total, 823 patients had autoantibody-positive RA (mean age 55 years, 67% female); 462 patients had autoantibody-negative RA (age 60 years, 64% female). Age, gender, and percentage of autoantibody-positive patients were stable throughout the inclusion periods. Disease activity significantly decreased over time within both groups. SDFR rates increased after introduction of treat-to-target (hazard ratio [HR] 2006-2010 relative to 1993-1996: 3.35 [95% CI 1.46 to 7.72; p = 0.004]; HR 2011-2016: 4.57 [95% CI 1.80 to 11.6; p = 0.001]) in autoantibody-positive RA, but not in autoantibody-negative RA. In autoantibody-positive RA, mortality decreased significantly after the introduction of treat-to-target treatment adjustments (HR 2006-2010: 0.56 [95% CI 0.34 to 0.92; p = 0.023]; HR 2011-2016: 0.33 [95% CI 0.14 to 0.77; p = 0.010]), but not in autoantibody-negative RA (HR 2006-2010: 0.79 [95% CI 0.40 to 1.56; p = 0.50]; HR 2011-2016: 0.36 [95% CI 0.10 to 1.34; p = 0.13]). Similarly, functional disability improved in autoantibody-positive RA for the periods after 2000 relative to 1993-1996 (range -0.16 [95% CI -0.29 to -0.03; p = 0.043] to -0.32 [95% CI -0.44 to -0.20; p < 0.001] units of improvement), but not in autoantibody-negative RA (range 0.10 [95% CI -0.12 to 0.31; p = 0.38] to -0.13 [95% CI -0.34 to 0.07; p = 0.20] units of improvement). Limitations to note were that treatment was not randomized-but it was protocolized and instrumental variable analysis was used to obtain comparable groups-and that a limited spread of ethnicities was included.

CONCLUSIONS

Although disease activity has improved in both autoantibody-positive and autoantibody-negative RA in recent decades, the response in long-term outcomes differed. We propose that it is time to subdivide RA into autoantibody-positive RA (type 1) and autoantibody-negative RA (type 2), in the hope that this leads to stratified treatment in RA.

An overview of autoantibodies in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic auto-immune disease principally effecting synovial joints. RA is characterized by immune cell infiltration in the joint. The presence of autoantibodies is a hallmark for the disease, among these are rheumatoid factor and antibodies against post-translational modified proteins like citrullination (ACPA) and carbamylation (anti-CarP antibodies). These autoantibodies may form immune complexes in the joint, leading to the attraction of immune cells. Based on the presence of these autoantibodies, RA patients can be subdivided in autoantibody positive and negative disease. Both subsets can be associated with genetic and environmental risk factors for RA, like the human leukocyte antigen (HLA) allele and smoking. Autoantibodies can already be detected years before disease onset in a subgroup of patients and at symptom onset a broad isotype spectrum is observed. This suggests that various events occur prior to the development of RA in which the first autoantibodies develop in predisposed individuals. Therefore, the presence of these autoantibodies can be useful in predicting future RA patients. Research on the characteristics and effector function of these autoantibodies is ongoing and will give more knowledge in the inflammatory responses underlying RA. This will give insight in the pathogenic role of autoantibodies in RA. Recent data are suggestive of a role for mucosal surfaces in the development of auto-immune responses associated with (the development of) RA. In conclusion, investigating the potential pathogenic effector functions of autoantibody isotypes and their molecular- and physicochemical-compositions might improve understanding of the disease origin and its underlying immunological processes. This may lead to the development of new therapeutic targets and strategies.

The Clinical Value of Autoantibodies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a highly heterogeneous syndrome in terms of clinical presentation, progression, and response to therapy. In such a complicated context, the identification of disease-related biomarkers would be undoubtedly helpful in assisting tailored approaches for every patient. Despite remarkable efforts, however, progress in new biomarker development and validation is dramatically slow. At present, none of the candidate genetic, cellular, or molecular biomarker has yet surpassed the clinical value of RA-specific autoantibodies, including rheumatoid factor (RF) and anti-citrullinated protein autoantibodies (ACPA). Rather, recent years have witnessed significant advancements in our understanding of the multiple roles that RF and ACPA play in RA pathophysiology. This has helped clarifying the mechanistic basis of the clinical associations of autoantibodies in RA. In this short review, we will briefly summarize the effector functions of RF and ACPA, and analyse how autoantibodies may help subclassifying RA patients in terms of clinical presentation and response to therapy.

Anti-citrullinated peptide antibodies and their value for predicting responses to biologic agents: a review

Anti-citrullinated peptide antibodies (ACPAs) play an important pathogenic role both at the onset and during the disease course. These antibodies precede the clinical appearance of rheumatoid arthritis (RA) and are associated with a less favorable prognosis, both clinically and radiologically. The objective of this work was to conduct a comprehensive review of studies published through September 2015 of ACPAs' role as a predictor of the therapeutic response to the biological agents in RA patients. The review also includes summary of the biology and detection of ACPAs as well as ACPAs in relation to joint disease and CV disease and the possible role of seroconversion. The reviews of studies examining TNF inhibitors and tocilizumab yielded negative results. In the case of rituximab, the data indicated a greater probability of clinical benefit in ACPA(+) patients versus ACPA(-) patients, as has been previously described for rheumatoid factor. Nonetheless, the effect is discreet and heterogeneous. Another drug that may have greater effectiveness in ACPA(+) patients is abatacept. Some studies have suggested that the drug is more efficient in ACPA(+) patients and that those patients show greater drug retention. In a subanalysis of the AMPLE trial, patients with very high ACPA titers who were treated with abatacept had a statistically significant response compared to patients with lower titers. In summary, the available studies suggest that the presence of or high titers of ACPA may predict a better response to rituximab and/or abatacept. Evidence regarding TNFi and tocilizumab is lacking. However, there is a lack of studies with appropriate designs to demonstrate that some drugs are superior to others for ACPA(+) patients.

CCR6(+) Th cell populations distinguish ACPA positive from ACPA negative rheumatoid arthritis

Introduction

Patients with rheumatoid arthritis (RA) can be separated into two major subpopulations based on the absence or presence of serum anti-citrullinated protein antibodies (ACPAs). The more severe disease course in ACPA⁺ RA and differences in treatment outcome between these subpopulations suggest that ACPA⁺ and ACPA⁻ RA are different disease subsets. The identification of T-helper (Th) cells specifically recognizing citrullinated peptides, combined with the strong association between HLA-DRB1 and ACPA positivity, point toward a pathogenic role of Th cells in ACPA⁺ RA. In this context we recently identified a potential pathogenic role for CCR6⁺ Th cells in RA. Therefore, we examined whether Th cell population distributions differ by ACPA status.

Methods

We performed a nested matched case–control study including 27 ACPA⁺ and 27 ACPA⁻ treatment-naive early RA patients matched for disease activity score in 44 joints, presence of rheumatoid factor, sex, age, duration of complaints and presence of erosions. CD4⁺CD45RO⁺ (memory) Th cell distribution profiles from these patients were generated based on differential chemokine receptor expression and related with disease duration.

Results

ACPA status was not related to differences in total CD4⁺ T cell or memory Th cell proportions. However, ACPA⁺ patients had significantly higher proportions of Th cells expressing the chemokine receptors CCR6 and CXCR3. Similar proportions of CCR4⁺ and CCR10⁺ Th cells were found. Within the CCR6⁺ cell population, four Th subpopulations were distinguished based on differential chemokine receptor expression: Th17 (CCR4⁺CCR10⁻), Th17.1 (CXCR3⁺), Th22 (CCR4⁺CCR10⁺) and CCR4/CXCR3 double-positive (DP) cells. In particular, higher proportions of Th22 (p = 0.02), Th17.1 (p = 0.03) and CCR4/CXCR3 DP (p = 0.01) cells were present in ACPA⁺ patients. In contrast, ACPA status was not associated with differences in Th1 (CCR6⁻CXCR3⁺; p = 0.90), Th2 (CCR6⁻CCR4⁺; p = 0.27) and T-regulatory (CD25^hiFOXP3⁺; p = 0.06) cell proportions. Interestingly, CCR6⁺ Th cells were inversely correlated with disease duration in ACPA⁻ patients (R² = −0.35; p < 0.01) but not in ACPA⁺ (R² < 0.01; p = 0.94) patients.

Conclusions

These findings demonstrate that increased peripheral blood CCR6⁺ Th cells proportions distinguish ACPA⁺ RA from ACPA⁻ RA. This suggests that CCR6⁺ Th cells are involved in the differences in disease severity and treatment outcome between ACPA⁺ and ACPA⁻ RA.

Missing Anticitrullinated Protein Antibody Does Not Affect Short-term Outcomes in Early Inflammatory Arthritis: From the Canadian Early Arthritis Cohort

Objective.

Anticitrullinated protein antibody (ACPA) is as sensitive as, but more specific than, rheumatoid factor (RF) and is detected earlier in rheumatoid arthritis (RA). Although part of the RA classification criteria, ACPA testing is not routinely paid for/accessible in all jurisdictions. The effect of missing ACPA testing was studied to determine whether failure to perform ACPA testing could cause a care gap in early inflammatory arthritis.

Methods.

Nearly 2000 patients (n = 1998) recruited to an early inflammatory arthritis cohort were allocated into 3 groups: (1) seropositive (either RF+ or ACPA+), (2) seronegative (RF− and ACPA−), and (3) missing ACPA and RF−. Analyses were adjusted for age, sex, symptom duration, and smoking status if p < 0.1. Disease Activity Score at 28 joints (DAS28) at 3 months was studied, because beyond then, disease activity is expected to determine ongoing treatment.

Results.

More seropositive patients fulfilled the 2010 American College of Rheumatology/European League Against Rheumatism RA criteria than seronegative patients. Group 3 was slightly older and had a smaller percentage of females, as well as shorter symptom duration and less smoking. At 3 months, group 3 was treated with fewer disease-modifying antirheumatic drugs and methotrexate (p < 0.00002) than groups 1 and 2, but there were no significant differences in DAS28, Health Assessment Questionnaire-Disability Index (HAQ-DI), proportion receiving corticosteroids, or physician’s/patient’s global assessments.

Conclusion.

There was no care gap in the RF-negative, unknown ACPA group because there were no significant differences in the DAS28, 3-month change in DAS28, or HAQ-DI, despite less treatment. Cost-effectiveness of ensuring ACPA testing availability in suspected RA is unknown because early outcomes did not differ, whether or not ACPA was available.

Elevated serum IgG4 defines specific clinical phenotype of rheumatoid arthritis

OBJECTIVES

To explore the correlation of serum IgG4 (sIgG4) with clinical manifestations or therapeutic response in rheumatoid arthritis (RA).

METHODS

Consecutive 136 RA patients were recruited and followed up at regular interval. SIgG4 was detected by immunonephelometry. Serial synovial tissue sections from 46 RA patients were stained immunohistochemically for IgG4.

RESULTS

Forty-six percent of 136 RA patients had elevated sIgG4. Patients with elevated sIgG4 had higher sIgG4/sIgG ratio, C-reactive protein, erythrocyte sedimentation rate, rheumatoid factor, and anticyclic citrullinated peptide antibodies than those with normal sIgG4 (all P < 0.05). Among 45 patients who received methotrexate and leflunomide therapy, 50% (9/18) of patients with elevated sIgG4 and 85% (23/27) of patients with normal sIgG4 reached therapeutic target (disease activity score of 28 joints < 3.2) at 6-month visit (χ(2) = 6.508, P = 0.011). IgG4-positive plasma cell count correlated positively with sIgG4, total synovitis score, and CD3-, CD20-, and CD38-positive cell counts (all P < 0.05).

CONCLUSIONS

Our results showed that elevated sIgG4 in RA is common and disproportional to total IgG and RA with elevated sIgG4 may be a specific clinical phenotype with higher disease activity, higher level of autoantibodies, and poor response to methotrexate and leflunomide therapy.

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.

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.

Anti-cyclic citrullinated peptide antibody is a good indicator for the diagnosis of rheumatoid arthritis

Objectives: Anti-cyclic citrullinated peptide (CCP) antibody has recently been used in the classification of rheumatoid arthritis (RA). This antibody is more specific than rheumatoid factor (RF) for the diagnosis of RA. The study objectives were to determine the sensitivity, specificity, positive and negative predictive values of anti-CCP in RA diagnosis.

Methodology: Eighty RA patients and 80 non-RA individuals were included in the study. Blood was collected from both arms of study subjects and tested for anti-CCP and RF antibodies. Relevant clinical information and laboratory profiles of the RA patients were evaluated using patients’ medical records and Integrated Laboratory Management System (ILMS), respectively.

Results: The sensitivity and specificity of anti-CCP were 35% and 100% respectively. The positive and negative predictive values were 100% and 61%, respectively. Positive anti-CCP was found significantly associated with multiple joint pain (p< 0.001) and hand’s joints pain (p=0.01), symmetrical joints involvement (p=0.015) and high CRP value (p<0.001). Anti-CCP was also found to have positive association with RF (p<0.001).

Conclusion: Anti-CCP is highly specific for the diagnosis of RA. High positive predictive value should be taken into consideration for effective treatment.

Blood monocyte chemotactic protein-1 (MCP-1) and adapted disease activity Score28-MCP-1: favorable indicators for rheumatoid arthritis activity

OBJECTIVE

We assessed blood pentraxin 3 (PTX3) and macrophage chemotactic factor-1 (MCP-1) levels as indicators of disease activity in rheumatoid arthritis (RA) patients, because data on disease activity score 28 (DAS28)-erythrocyte sedimentation rate (ESR) and DAS28-C-reactive protein (CRP) are still imperfect.

METHODS

In 111 patients with RA, we examined longitudinal and cross-sectional correlations of blood PTX3, MCP-1, CRP, and ESR levels with measures of clinical arthritic activity, namely, swollen joint count (SJC), tender joint count (TJC), visual analog scale for general health (GH), DAS28, and adapted DAS28-MCP-1.

RESULTS

Blood MCP-1, but not PTX3, was significantly correlated with SJC, TJC, DAS28, and DAS28-CRP. DAS28-MCP-1 was strongly correlated with DAS28 (r  = 0.984, P<0.001) and DAS28-CRP (r  = 0.971, P<0.001), and modestly correlated with CRP (r  = 0.350, P<0.001), and ESR (r  = 0.386, P<0.001). Similarly, the duration of arthritic symptoms, but not sex, was significantly correlated with variables of arthritic activity. In particular, DAS28-MCP-1 significantly correlated with DAS28 during a 6-month period (r  = 0.944, P<0.001; r  = 0.951, P<0.001; r  = 0.862, P<0.001; and r  = 0.865, P<0.001 for month 0, 1, 3, and 6, respectively).

CONCLUSION

Blood MCP-1 and adapted DAS28-MCP-1, but not blood PTX3, may be useful in monitoring RA activity.

Anti-citrullinated peptide antibodies in the serum of heavy smokers without rheumatoid arthritis. A differential effect of chronic obstructive pulmonary disease?

The objective of this study is to analyse the frequency and levels of anti-citrullinated peptide/protein antibodies (ACPA) in the serum of non-rheumatoid arthritis (RA) heavy smokers with and without chronic obstructive pulmonary disease (COPD) and compare them with healthy never smokers and patients with RA. Serum samples of 110 heavy smokers without RA, 209 healthy never smokers and 134 patients with RA were tested for ACPA using a commercial anti-cyclic citrullinated peptide antibodies (CCP2) test and a homemade chimeric fibrin/filaggrin citrullinated synthetic peptide (anti-CFFCP) ELISA test. The frequency of positive results and autoantibody levels were compared between groups. The prevalence of the two types of ACPA was slightly higher in heavy smokers than in never smokers, although the difference was not significant, and significantly lower than in RA patients. The highest prevalence of positive ACPA in heavy smokers was found in subjects with COPD (7.4% of positive anti-CFFCP in patients with COPD in comparison with 2.4% in never smokers: OR 3.26; 95% CI 0.85-12.6, p = 0.089). Mean serum levels of ACPA in heavy smokers were not significantly different from those of never smokers. Heavy smokers with COPD had significantly higher levels of anti-CFFCP than those without COPD, although almost all patients had serum levels below the cut-off values. The prevalence of ACPA in heavy smokers without RA is low, but seems to be higher in heavy smokers with COPD. Larger studies are necessary to confirm these findings and determine the relationship between ACPA and lung disease.

Rheumatoid factor and antibodies against citrullinated peptides in Moroccan patients with rheumatoid arthritis: association with disease parameters and quality of life

We aimed to evaluate the immunological status and its relationships with disease-related parameters of activity, severity and quality of life in Moroccan patients with rheumatoid arthritis (RA). Two hundred forty-five consecutive patients with RA were recruited. The following data were collected: demographic characteristics, disease duration (years), disease activity (evaluated by the disease activity score, DAS28), structural damage (evaluated by Sharp's method as modified by van der Heijde), functional disability (assessed by using the Moroccan version of the Health Assessment Questionnaire, HAQ) and quality of life (by using the Arabic version of the Medical Outcomes Study Short Form 36 Health Survey: the SF-36). Immunological status (rheumatoid factor rate, RF) and antibodies against citrullinated peptides rate (ACPAs) by the Elisa method were examined. ACPAs were detected in 75.1% of patients with a mean rate of 79.2 ± 43.8 UI. RF was detected in 80.8% of patients with a mean rate of 80.1 ± 50.6 UI. Patients with positive RF and ACPAs had higher disease activity, impaired functional ability, severe structural damage, more ocular symptoms and altered aspects of quality of life. In univariate analysis, higher levels of ACPAs were significantly correlated with the age at onset (r = 0.307), disease duration (r = 0.520), disease activity (DAS28) (r = 0.531), Sharp score (r = 0.431), and with the deterioration of all domains of SF-36 (for all p ≤ 0.01). RF levels were correlated with disease duration (r = 0.517), disease activity (r = 0.470), functional disability (r = 0.521), and the alteration of physical domains of SF-36 (for all p ≤ 0.01). In multivariate analysis, the main factors associated to ACPAs and RF levels were functional disability, structural damage and impaired QoL. Furthermore, using the SF-36 scores as dependent variables, the impairment of physical domains and the domain of vitality were significantly associated with ACPA levels while the decrease of the domain of physical function was associated with the level of RF. Our study suggests that the presence and the levels of ACPAs and RF in our RA patients are associated with more active disease, more severe joint damage, worst functional disability and altered aspects of quality of life.

Anti-CCP antibodies: the past, the present and the future

Rheumatoid arthritis (RA) is an autoimmune disease characterized by autoantibodies against citrullinated antigens. The importance of citrulline for the epitopes bound by these autoantibodies, referred to as ACPA (anti-citrullinated peptide/protein antibodies), was first described in 1998. In addition to citrullinated proteins, cyclic citrullinated peptides (CCP) can also be used as test substrates for detecting ACPA. The standard test for these antibodies is the second-generation CCP (CCP2) test, which is one of the best in terms of sensitivity and specificity. The generation of ACPA is an early event in the disease course, and is dependent on the presence of certain MHC class II alleles. ACPA in the inflamed synovium have been shown to associate with citrullinated antigens to form immune complexes, resulting in progression of the inflammatory process. The involvement of ACPA in the chronicity of RA is probably the reason why ACPA-positive patients have a more erosive disease course than ACPA-negative patients. The presence of ACPA has been included in the 2010 RA classification criteria. Thus, it is important to further standardize ACPA testing, for example by including an internal serum standard, which may lead to a better distinction between low and high ACPA levels.

Relationship between time-integrated disease activity estimated by DAS28-CRP and radiographic progression of anatomical damage in patients with early rheumatoid arthritis

Background

The main aim of the study was to investigate the relationship between persistent disease activity and radiographic progression of joint damage in early rheumatoid arthritis (ERA).

Methods

Forty-eight patients with active ERA was assessed every 3 months for disease activity for 3 years. Radiographic damage was measured by the Sharp/van der Heijde method (SHS). The cumulative inflammatory burden was estimated by the time-integrated values (area under the curve-AUC) of Disease Activity Score 28 joint based on C-reactive protein (DAS28-CRP) in rapid progressors versus non-progressors. Bland and Altman's 95% limits of agreement method were used to estimate the smallest detectable difference (SDD) of radiographic progression. The relationship between clinical and laboratory predictors of radiographic progression and their interactions with time was analysed by logistic regression model.

Results

After 3-years of follow-up, radiographic progression was observed in 54.2% (95%CI: 39.8% to 67.5%) of patients and SDD was 9.5 for total SHS. The percentage of patients with erosive disease increased from 33.3% at baseline to 76% at 36 months. The total SHS of the progressors worsened from a median (interquartile range) of 18.5 (15-20) at baseline to 38.5 (34-42) after 3 years (p < 0.0001) whereas non-progressors worsened from a median of 14.5 (13-20) at baseline to 22.5 (20-30) after 3 years (p < 0.001). In the regression model, time-integrated values of DAS28-CRP and anti-CCP positivity have the highest positive predictive value for progression (both at level of p < 0.0001). Radiographic progression was also predicted by a positive IgM-RF (p0.0009), and a high baseline joint damage (p = 0.0044).

Conclusions

These data indicate that the level of disease activity, as measured by time-integrated DAS28-CRP, anti-CCP and IgM-RF positivity and a high baseline joint damage, affects subsequent progression of radiographic damage in ERA.