IgM Rheumatoid Factor Research Articles

Síndrome de Sjögren primario: autoanticuerpos y su relación con las manifestaciones clínicas y la histología de las glándulas salivales menores

Introduction/ObjectiveTo evaluate the association between autoantibodies with clinical manifestations (extraglandular and glandular) and histopathological findings of minor salivary gland biopsy in primary Sjögren's syndrome. Materials and methodsObservational, descriptive, and cross-sectional study. Forty-seven patients with primary Sjögren's syndrome according to the ACR/EULAR 2016 criteria were included. A face-to-face survey, a review of medical records, and the measurement of autoantibodies anti-Ro 52, anti-Ro 60, anti-La, antinuclear antibodies, rheumatoid factor IgA, IgG and IgM, and anti-alpha fodrin IgA and IgG were done. Characterization of the population and analysis of the association between clinical characteristics, autoantibodies, and histopathology were performed. ResultsAssociation of anti-alpha fodrin IgA and anti-Ro 52 Ab was found with pulmonary involvement (P=.014 and P=.031 respectively) and anti-La antibodies with haematological manifestations, specifically leukopenia (P=.011), lymphopenia (P=.023), and anaemia (P=.09). We found no association between the histopathological findings of the minor salivary gland biopsy and extraglandular manifestations. ConclusionsThe activation of B cells, reflected in the increased production of autoantibodies, is related to extraglandular manifestations in primary Sjögren's syndrome, which is observed more frequently in patients with earlier diagnosis.

Lack of comparability of immunoassays for rheumatoid factor isotypes.

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterised by the presence of autoantibodies that are used for classification of the disease. Though routine diagnostics is commonly restricted to measuring rheumatoid factor (RF) and anti-citrullinated protein antibodies, detection of RF IgM, IgG and IgA isotypes, may increase the power of RA serodiagnosis by reducing the number of seronegative patients as well as provide prognostic information. The agglutination-based RF assays, such as nephelometry or turbidimetry, are unable to differentiate isotypes. We compared three different immunoassays used in current laboratory practice to detect RF isotypes. We tested 117 consecutive serum samples that were positive for total RF at nephelometry, from 55RA and 62non-RA subjects. IgA, IgG, and IgM isotypes of RF were tested by immunoenzymatic (ELISA, Technogenetics), fluoroenzymatic (FEIA, ThermoFisher) and chemiluminescence (CLIA, YHLO Biotech Co.) immunoassays. Diagnostic performance differed considerably between the assays, especially with regard to RF IgG isotype. Agreement among methods by Cohen's kappa ranged from 0.05 (RF IgG CLIA vs. FEIA) to 0.846 (RF IgM CLIA vs. FEIA). The poor agreement observed in this study indicates substantial lack of comparability among assays for RF isotypes. Harmonization of these tests requires further efforts before their measurement can be used in clinical practice.

Radiographic airway abnormalities in untreated early rheumatoid arthritis are associated with peripheral neutrophil activation

BackgroundThe role of the lung for the initiation and progression of rheumatoid arthritis (RA) is still unclear. Up to 10% of RA patients develop interstitial lung disease which remains a clinical challenge. Understanding early disease mechanisms is of great importance. The objective of this study was to determine whether there is an association between peripheral neutrophil phenotypes and presence of pulmonary abnormalities (PA) on chest high-resolution computed tomography (HRCT) in untreated early RA (ueRA).MethodsClinical data and blood were collected, and HRCT performed at diagnosis on 30 consecutive anti-citrullinated protein antibody (ACPA) and/or rheumatoid factor (RF) positive ueRA patients. HRCTs were evaluated for the presence of RA-associated parenchymal, airway and/or pleural abnormalities. Expression of phenotype markers on neutrophils were determined by flow cytometry. Levels of calprotectin, ACPA and RF were measured using immunoassays.ResultsThe frequency of having any PA was 60%. Airway abnormalities were present in 50%, parenchymal nodules in 43% and interstitial lung abnormalities (ILA) in 10%. Unsupervised multivariate data analysis showed clustering of any PA with neutrophil activation, parameters of inflammation and RF titres. In univariate analysis, the patients with PA displayed significantly increased CD11b and decreased CD62L expression on neutrophils (1.2-fold, p = 0.014; 0.8-fold, p = 0.012) indicating activation and significantly increased RF IgM titre and CRP (5.7-fold, p = 0.0025; 2.3-fold, p = 0.0035) as compared to no PA. Titres of RF, but not ACPA, correlated with expression of the neutrophil activation marker CD11b. A stratified analysis demonstrated that airway involvement was the PA subtype with the strongest association with neutrophil activation.ConclusionWe report a strong association between radiographic airway findings and activation of circulating neutrophils in early RA supporting a role of innate immunity and the lung at disease onset. Our results also indicate different contributions of RF and ACPA in the RA pathogenesis.

Effects of tofacitinib therapy on arginine and methionine metabolites in association with vascular pathophysiology in rheumatoid arthritis: A metabolomic approach.

Rheumatoid arthritis (RA) has been associated with changes in lipid, arginine and NO metabolism with increased cardiovascular (CV) risk. The aim of this study is to evaluate the effect of tofacitinib, a Janus kinase (JAK) inhibitor, on arginine and methionine metabolism in correlation with inflammation, functional and pathological vascular changes during one-year treatment of patients with RA. Thirty RA patients with active disease were treated with either 5 mg bid or 10 mg bid tofacitinib for 12 months. We determined DAS28, CRP, IgM rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) levels. We assessed brachial artery flow-mediated vasodilation (FMD), carotid intima-media thickness (IMT) and pulse-wave velocity (PWV) by ultrasound at baseline and after 6 and 12 months. We also determined plasma L-arginine, L-citrulline, L-ornithine, inducible nitric oxide synthase (iNOS), asymmetric (ADMA) and symmetric dimethylarginine (SDMA), L-N-monomethyl-arginine (L-NMMA), cysteine, homocysteine, and methionine levels at these time points. Twenty-six patients (13 on each arm) completed the study. CRP, ESR and DAS28 decreased significantly during one-year treatment with tofacitinib. Arginine and ADMA showed a negative univariate correlation with CRP but not with FMD, PWV or IMT. Tofacitinib at 10 mg bid significantly increased L-arginine, L-ornithine, iNOS and methionine levels after 12 months. ADMA and SDMA levels did not change in our study. Methionine showed negative correlation with FMD at baseline and positive correlation with PWV after 12 months. No change was observed in FMD and PWV but a significant increase was measured in IMT at 6 and 12 months. Multivariate analysis indicated variable correlations of L-arginine, L-citrulline, ADMA, L-NMMA, homocysteine and methionine with DAS28, CRP, ESR and RF but not with anti-CCP after one-year treatment. With respect to vascular pathophysiology, only PWV and methionine correlated with each other. One-year tofacitinib treatment suppressed systemic inflammation and improved functional status in RA. FMD, PWV have not been affected by one-year tofacitinib treatment., while IMT increased further despite treatment. Increased arginine and methionine might contribute to the anti-inflammatory effects of tofacitinib. Increased arginine availability with no changing ADMA may protect FMD and PWV from deterioration. The increase of IMT in the anti-inflammatory environment cannot be explained by arginine or methionine metabolism in this study.

Value of diagnosing immunological phenomena in patients with suspected endocarditis

PurposeImmunological phenomena are a minor criteria in the modified Duke Criteria for endocarditis. Given the changes in epidemiology and diagnostics, the added value of determining these phenomena in today’s patients with suspected endocarditis is unknown.MethodsIn a retrospective cohort study of all patients with suspected endocarditis admitted to our hospital and discussed in our endocarditis team, we determined the proportion of patients classified as definite endocarditis because of either positive IgM rheumatoid factor (IgM RF), haematuria, or Roth’s spots on ophthalmology consultation. We also determined diagnostic accuracy of each of these immunological phenomena separately and combined.ResultsOf 285 patients included, 138 (48%) had definite endocarditis and at least one immunological test was performed in 222 patients (78%). Elevated IgM RF was found in 22 of 126 patients tested (17%), haematuria in 78 of 196 tested (40%) and Roth’s spots in six of 120 tested (5%). Eighteen of 138 patients with definite IE (13%) were classified as such because of a positive IgM RF, haematuria or Roth’s spots. Haematuria had the highest sensitivity: 50.5% (95% CI 40.4–60.6) and Roth’s spots the highest specificity: 98.3% (95% CI 90.8–99.9). The diagnostic accuracy results were robust in a sensitivity analysis aimed at avoiding incorporation bias.ConclusionAmong patients with a clinical suspicion of endocarditis, recommended systematic testing for immunological phenomena helped classify more patients as definite IE and is useful to confirm the diagnosis of endocarditis.

Synovial gene signatures associated with the development of rheumatoid arthritis in at risk individuals: A prospective study

ObjectiveTo identify molecular changes in synovium before arthritis development in individuals at risk of developing rheumatoid arthritis (RA). Materials and methodsWe included 67 IgM rheumatoid factor and/or anti-citrullinated protein antibody positive individuals with arthralgia but without arthritis. Synovial biopsies were collected after which individuals were prospectively followed for at least 2 years during which 17 developed arthritis. An exploratory genome-wide transcriptional profiling study was performed in 13 preselected individuals to identify transcripts associated with arthritis development (n = 6). Findings were validated using quantitative real-time PCR and immunohistochemistry in the total cohort. ResultsMicroarray-based survival analyses identified 5588 transcripts whose expression levels in synovium were significantly associated with arthritis development. Pathway analysis revealed that synovial tissue of at risk individuals who later developed arthritis display higher expression of genes involved in adaptive immune response-related pathways compared to at risk individuals who did not develop arthritis. Lower expression was observed for genes involved in extracellular matrix receptor interaction, Wnt-mediated signal transduction and lipid metabolism. Two-way hierarchical clustering analyses of a 27-gene signature separated the total at risk cohort into two groups, where pre-RA individuals preferred to cluster together. Immunohistochemistry studies revealed more podoplanin positive cells and lower lipid droplet staining in synovial tissue from pre-RA individuals. ConclusionSynovial alterations in adaptive immune response and lipid metabolism are associated with future development of arthritis. Since this data show synovial changes without overt cellular infiltration, these may be attributed to preclinical changes in resident synovial tissue cells such as fibroblasts, macrophages and tissue resident T cells.

ACCP-negative rheumatoid arthritis – clinical and immunological features

Depending on the presence of laboratory biomarkers: rheumatoid factor IgM and anti-cyclic citrullinated peptide antibodies (ACCP), “seropositive” and “seronegative” variants of rheumatoid arthritis (RA) are distinguished. Immunological subtypes differ in risk factors, immunopathogenesis, and the course of the disease. A review of data concerning immunology and clinical features of ACCP-negative rheumatoid arthritis is presented. The presence of ACCP in the peripheral blood reflects the progressive erosive process with a predominance of the inflammatory component and involvement of the B cells. Proliferative changes predominate in the ACCPnegative subtype; disorders associated with the T-cell link, primarily with CD4+ T-lymphocytes, play an important role in pathogenesis. This variant of the disease is characterized by a less pronounced erosive process, but the inflammatory activity in both subtypes of RA can be comparable. Early diagnosis, regular monitoring of the disease activity and the «treat to target» strategy are recommended for both positive and negative ACCP RA, however, the effectiveness of individual drugs in these subtypes may vary significantly.

IgA rheumatoid factor in rheumatoid arthritis.

Rheumatoid factor (RF) is a well-established marker for the diagnosis and classification of rheumatoid arthritis (RA). Most studies evaluated IgM RF or isotype-nonspecific total RF assays. We evaluated the added value of IgA RF in this context. An international sample cohort consisting of samples from 398 RA patients and 1073 controls was tested for IgA RF with 3 commercial assays. For all RA patients and 100 controls essential clinical and serological data for ACR/EULAR classification were available. The sensitivity of IgA RF for diagnosing RA was lower than the sensitivity of IgM RF. Differences in numerical values between IgA RF assays were observed. With all assays, the highest IgA RF values were found inpatients with primary Sjögren's syndrome. Double positivity for IgM RF and IgA RF had a higher specificity for RA than either IgM RF or IgA RF. The sensitivity of double positivity was lower than the sensitivity of either IgA RF or IgM RF. Single positivity for IgA RF was at least as prevalent in controls than in RA patients. Adding IgA RF to IgM RF and anti-citrullinated protein antibodies (ACPA) did not affect RA classification. However, combined positivity for IgA RF, IgM RF and IgG ACPA had a higher specificity and lower sensitivity for RA classification than positivity for either of the antibodies. IgA RF showed a lower sensitivity than IgM RF. Combining IgA RF with IgM RF and ACPA did not improve sensitivity of RA classification. Combined positivity (IgA-RF/IgM-RF/ACPA) increased specificity.

Frequency of serological markers of rheumatoid arthritis in patients with IgA anti-β2 glycoprotein I antibodies.

AimTo determine the frequency of serological markers of RA in patients with anti‐β2 glycoprotein I antibodies (aβ2GPI) of IgA isotype.Material and MethodsA retrospective study was conducted on 67 patients with aβ2GPI‐IgA. Ninety healthy blood donors (HBD) were used as a control group. IgG anti‐cyclic citrullinated peptides antibodies (CCP‐Ab) and rheumatoid factors (RF) IgG, IgA, and IgM were detected by enzyme‐linked immunosorbent assay (ELISA).ResultsSeventeen patients and eight HBD had CCP‐Ab and/or RF (25.4% vs. 8.9%, p = 0.005, CI 95% [14.95; 35.79], odds ratio = 3.5). The frequency of CCP‐Ab was significantly higher in patients than in healthy subjects (14.9% vs. 3.3%, p = 0.009). IgA isotype of RF was significantly higher in patients than in controls (7.5% vs. 0%, p = 0.02). In male patients, CCP‐Ab and/or RF were more frequent than in healthy male subjects (37.5% vs. 11.8%, p = 0.02). In patients, no correlation was found between the levels of aβ2GPI‐IgA and CCP‐Ab (r = 0.082, p = 0.51). There was no correlation between the level aβ2GPI‐IgA and the level of the isotypes of RF (IgG, IgA, and IgM) in patients (r = 0.1, p = 0.37; r = 0.17, p = 0.17 and r = 0.07, p = 0.59 respectively).ConclusionFrequencies of CCP‐Ab and RF are high in patients with aβ2GPI‐IgA suggesting that these patients are susceptible to developing RA.

Accuracy and tolerability of self-sampling of capillary blood for analysis of inflammation and autoantibodies in rheumatoid arthritis patients—results from a randomized controlled trial

BackgroundRheumatoid arthritis (RA) requires early diagnosis and tight surveillance of disease activity. Remote self-collection of blood for the analysis of inflammation markers and autoantibodies could improve the monitoring of RA and facilitate the identification of individuals at-risk for RA.ObjectiveRandomized, controlled trial to evaluate the accuracy, feasibility, and acceptability of an upper arm self-sampling device (UA) and finger prick-test (FP) to measure capillary blood from RA patients for C-reactive protein (CRP) levels and the presence of IgM rheumatoid factor (RF IgM) and anti-cyclic citrullinated protein antibodies (anti-CCP IgG).MethodsRA patients were randomly assigned in a 1:1 ratio to self-collection of capillary blood via UA or FP. Venous blood sampling (VBS) was performed as a gold standard in both groups to assess the concordance of CRP levels as well as RF IgM and CCP IgG. General acceptability and pain during sampling were measured and compared between UA, FP, and VBS. The number of attempts for successful sampling, requests for assistance, volume, and duration of sample collection were also assessed.ResultsFifty seropositive RA patients were included. 49/50 (98%) patients were able to successfully collect capillary blood. The overall agreement between capillary and venous analyses for CRP (0.992), CCP IgG (0.984), and RF IgM (0.994) were good. In both groups, 4/25 (16%) needed a second attempt and 8/25 (32%) in the UA and 7/25 (28%) in the FP group requested assistance. Mean pain scores for capillary self-sampling (1.7/10 ± 1.1 (UA) and 1.9/10 ± 1.9 (FP)) were significantly lower on a numeric rating scale compared to venous blood collection (UA: 2.8/10 ± 1.7; FP: 2.1 ± 2.0) (p=0.003). UA patients were more likely to promote the use of capillary blood sampling (net promoter score: +28% vs. −20% for FP) and were more willing to perform blood collection at home (60% vs. 32% for FP).ConclusionsThese data show that self-sampling is accurate and feasible within one attempt by the majority of patients without assistance, allowing tight monitoring of RA disease activity as well as identifying individuals at-risk for RA. RA patients seem to prefer upper arm-based self-sampling to traditional finger pricking.Trial registrationDRKS.de Identifier: DRKS00023526. Registered on November 6, 2020.

Relationship of cytokine level dynamics with longterm results of early rheumatoid arthritis therapy

The aim of the work – to research the relationship between the dynamics of cytokine levels in the early period (the first 12 and 24 weeks) of pharmacotherapy for rheumatoid arthritis (RA) and long-term outcomes in patients with the disease.Material and methods. The analysis included 93 patients with early RA. The majority of patients were women (n=77), middle-aged (58 [49; 66] years), with an early stage of the disease (the duration of the disease is 7 [4–11.5] months), seropositive according to IgM rheumatoid factor and cyclic citrullinated peptide antibodies, who had high (59.7%) or moderate (38.8%) disease activity.The concentration of 27 cytokines in the blood serum was determined with the help of multiplex xMAP technology on the Bio-Plex array system analyzer (BIORAD, USA). Repeated clinical examination of patients was carried out after 6 years.Results. Patients who achieved remission/low disease activity SDAI after 6 years had a lower level of IL-6 (7.7 [7.4; 23.3]), IL-9 (13.5 [9.1; 18.9]) 12 weeks after the start of therapy; lower IL-9 level (12.6 [6.8; 16.2]) 24 weeks after the start of the treatment, compared with the group of patients with moderate and high inflammatory activity (23.5 [12.4; 69.5], 17.8 [15; 29] and 18.5 [14.2; 22.8] respectively).Findings. The assessment of the level of proinflammatory cytokines (IL-6, IL-17), immunoregulatory cytokine IL-9 allows to evaluate the activity of the disease more fully and identify a group of patients, who needs the therapy intensification.

Predicting the effectiveness of methotrexate therapy based on basal expression of the AMP-activated protein kinase gene in the blood of patients with rheumatoid arthritis

Objective: to search for an association between basal expression of the AMP-activated protein kinase (adenosine monophosphate-activated protein kinase, AMPK) gene in the blood of patients with rheumatoid arthritis (RA) and disease activity, as well as joint destruction before and after 24 months of methotrexate (MT) therapy.Patients and methods. The study included 40 patients with RA who met the 1987 ACR classification criteria, with a disease duration of not more than 2 years, with a mean age of 47.5±15.5 years. All patients received 15 mg/week of MT. The number of swollen joints (SJC) out of 44, the number of tender joints (TSC) out of 53, the duration of morning stiffness (in minutes) and RA activity were assessed using the DAS28 index. The concentration of CRP and IgM rheumatoid factor (RF), antibodies to cyclic citrullinated peptide (ACCP) were assessed. To evaluate the radiological progression of RA, the Sharp method modified by van der Heijde was used. Gene expression in peripheral blood cells was determined by reverse transcriptase reaction and real-time polymerase chain reaction.Results and discussion. During MT therapy, there was a decrease in disease activity by DAS28 index, CRP level, duration of morning stiffness, SJC and TJC. After 2 years, there were no statistically significant changes in the number of erosions, while the number of joints with narrowing of the joint space increased by the end of the study (p=0.004). Treatment with MT resulted in a decrease in AMPK expression. At the same time, patients who achieved remission had the highest level of AMPK before therapy, as did seronegative patients compared to seropositive ones. Based on the ROC analysis, the threshold value of AMPK gene expression was determined, which makes it possible to predict a high probability of a positive effect of MT therapy.Conclusion. AMPK gene expression is associated with disease activity. Its high initial blood level in RA patients is associated with greater efficiency of MT and, possibly, plays a protective role. With an AMPK gene expression index greater than 3.83, the probability of a positive response to MT is high.

False-positive detection of IgM anti-severe acute respiratory syndrome coronavirus 2 antibodies in patients with rheumatoid arthritis: Possible effects of IgM or IgG rheumatoid factors on immunochromatographic assay results.

Objectives:The severe acute respiratory syndrome coronavirus 2 causes coronavirus disease 2019. A serological test is conducted to determine prior infection by severe acute respiratory syndrome coronavirus 2. We investigated whether the results of anti-severe acute respiratory syndrome coronavirus 2 antibody tests are modified in patients with rheumatoid arthritis.Methods:Patients in Japan with rheumatoid arthritis were recruited at Sagamihara Hospital from July 2014 to October 2015 (n = 38; 2014 cohort) and at Tokyo Hospital from June to October 2020 (n = 93; 2020 cohort). Anti-severe acute respiratory syndrome coronavirus 2 antibodies were measured by electrochemiluminescence immunoassay or immunochromatographic assay.Results:Anti-severe acute respiratory syndrome coronavirus 2 antibodies were not detected in any of the samples from rheumatoid arthritis patients tested by electrochemiluminescence immunoassay. Anti-severe acute respiratory syndrome coronavirus 2 antibodies were detected by immunochromatographic assay in the 3 (7.9%) serum samples in the 2014 cohort and 15 (16.1%) serum samples in the 2020 cohort. The IgM rheumatoid factor levels were increased in rheumatoid arthritis patients with IgM anti-severe acute respiratory syndrome coronavirus 2 antibodies detected by immunochromatographic assay (mean ± standard deviation (IU/ml), 1223.0 ± 1308.7 versus 503.6 ± 1947.2; P = 0.0101). The levels of IgG rheumatoid factor were also upregulated in rheumatoid arthritis patients with IgM anti-severe acute respiratory syndrome coronavirus 2 antibodies detected by immunochromatographic assay (4.0 ± 0.7 versus 2.4 ± 0.9; P = 0.0013).Conclusion:The results of IgM anti-severe acute respiratory syndrome coronavirus 2 antibody testing by immunochromatographic assay are modified by IgM or IgG rheumatoid factors in rheumatoid arthritis patients.

Erosive arthritis autoantibodies in systemic sclerosis

ObjectiveWe aimed to evaluate in two large SSc French cohorts the prevalence and associated factors with the autoantibodies linked to erosive arthritis. Methods448 SSc patients were recruited from May 2015 to January 2019. Standardized clinical and laboratory variables were collected in accordance with the EUSTAR database. ELISAs for IgM rheumatoid factor (RF), IgG anti-citrullinated proteins (ACPA) and IgG anti‐carbamylated proteins antibodies (anti-CarP) were all determined in a central laboratory. The prevalence and clinical associations of the different antibodies were investigated. ResultsRF positivity was observed in 113 patients (25%) compared to 39 (9%) for ACPA and 63 (14%) for anti-CarP antibodies. Through multivariate regression analysis, both RF and ACPA positivity resulted to be associated with RA overlap disease (OR 5.7, 95% CI 2.3–13.8 and OR 44.1, 95% CI 15.4–126.3, respectively). Additionally, ACPA was found to be significantly related to synovitis/ tenosynovitis (OR 1.7, 95% CI 1.0–2.6). RF positivity was associated to a "vascular subset" (i.e. any major vascular complication) (OR 2.1, 95% CI 1.3–3.4). Moreover, anti-CarP antibodies were associated with a fibrotic subset and with digital ulcers (OR 2.0, 95% CI 1.1–3.6 and OR 1.9, 95% CI 1.1–3.4). ConclusionWe corroborated that ACPA could be useful in identifying patients with a more prominent joint disease and RA overlap disease. Of the most interest we found that anti-CarP antibodies could be a relevant biomarker related to fibrotic skin and lung disease.

Lack of cross-reactivity between rheumatoid factor IgM and anti-S1 receptor binding domain of SARS-CoV-2 IgM: a case-control study.

Since the onset of the COVID-19 outbreak, concern has been raised about reliability of SARS-CoV-2 serological tests in people with serum positivity for rheumatoid factor (RF), due to its ability to interfere during tests carried out with immunoassay techniques, leading to false positive results. The aim of this study was to analyse, on sera from RF seropositive rheumatoid arthritis (RA) patients, the interference between RF IgM and anti-S1 RBD IgM. The study was conducted on consecutive patients affected by RF seropositive RA and, as control group, COVID-19 patients with SARS-CoV-2 pneumonia hospitalised at Sapienza University of Rome from April 2020 and April 2021. Serum samples from COVID-19 patients during their hospitalisation were collected, while RA subjects' samples were harvested prior to the onset of the COVID-19 pandemic. All samples were tested for RF IgM using nephelometry and ELIA, and for anti-S1 RBD IgM by ELISA. Forty RF seropositive RA and 42 COVID-19 patients were enrolled. In all RA patients, both nephelometric assay and ELIA showed RF IgM positivity, while only one patient of the control group tested positive for RF IgM by nephelometric assay and ELIA. IgM directed to S1 RBD were not detected in sera of RA patients, while all COVID-19 patients presented anti-S1 RBD IgM (median anti-S1 RBD IgM COVID-19 vs. RA: 368.5 IU/mL, IQR 654 IU/mL vs. 18.45 IU/mL, IQR 20 IU/mL; p<0.0001). This study confirmed the lack of cross-reactivity between RF and anti-S1 RBD IgM, offering to clinicians a valuable tool for a better management of RA patients undergoing SARSCoV-2 serological tests.

IL-40: A New B Cell-Associated Cytokine Up-Regulated in Rheumatoid Arthritis Decreases Following the Rituximab Therapy and Correlates With Disease Activity, Autoantibodies, and NETosis.

BackgroundInterleukin 40 (IL-40) is a newly identified B cell-associated cytokine implicated in humoral immune responses and B cell homeostasis. As B cells play a pivotal role in autoimmunity, we investigated the function of IL-40 in rheumatoid arthritis (RA).MethodsIL-40 expression was determined in the synovial tissue from RA and osteoarthritis (OA) patients. IL-40 was analysed in the serum/synovial fluid of patients with RA (n=50), systemic lupus erythematosus (SLE, n=69), OA (n=44), and healthy controls (HC, n=50). We assessed the changes of IL-40 levels in RA patients following the B cell depletion by rituximab (n=29) or after the TNF inhibition by adalimumab (n=25). We examined the relationship between IL-40, disease activity, autoantibodies, cytokines, and NETosis markers. Effect of IL-40 on synovial fibroblasts was determined.ResultsIL-40 was overexpressed in RA synovial tissue, particularly by synovial lining and infiltrating immune cells. The levels of IL-40 were up-regulated in the synovial fluid of RA versus OA patients (p<0.0001). Similarly, IL-40 was increased in the serum of RA patients compared to HC, OA, or SLE (p<0.0001 for all) and decreased after 16 and 24 weeks (p<0.01 and p<0.01) following rituximab treatment. No significant effect of adalimumab on IL-40 was observed. IL-40 levels in RA patients correlated with rheumatoid factor-IgM and anti-cyclic citrullinated peptides (anti-CCP) in the serum (p<0.0001 and p<0.01), as well as in the synovial fluid (p<0.0001 and p<0.001). Synovial fluid IL-40 was also associated with disease activity score DAS28 (p<0.05), synovial fluid leukocyte count (p<0.01), neutrophil attractants IL-8 (p<0.01), MIP-1α (p<0.01), and markers of neutrophil extracellular traps externalization (NETosis) such as proteinase 3 (p<0.0001) and neutrophil elastase (p<0.0001). Synovial fibroblasts exposed to IL-40 increased the secretion of IL-8 (p<0.01), MCP-1 (p<0.05), and MMP-13 (p<0.01) compared to the unstimulated cells.ConclusionsWe show the up-regulation of IL-40 in RA and its decrease following B cell depleting therapy. The association of IL-40 with autoantibodies, chemokines, and markers of NETosis may imply its potential involvement in RA development. Moreover, IL-40 up-regulates the secretion of chemokines and MMP-13 in synovial fibroblasts, indicating its role in the regulation of inflammation and tissue destruction in RA.

A Comparative Study to Test the Efficacy of Rheumatoid Factor Igm Antibody Detection by Latex Agglutination and Nephelometry

A Comparative Study to Test the Efficacy of Rheumatoid Factor Igm Antibody Detection by Latex Agglutination and Nephelometry

Combinations of Anticyclic Citrullinated Protein Antibody, Rheumatoid Factor, and Serum Calprotectin Positivity Are Associated With the Diagnosis of Rheumatoid Arthritis Within 3 Years.

ObjectiveTo evaluate the prevalence of elevations of anti‐cyclic citrullinated peptide‐3 (anti‐CCP3) antibody, rheumatoid factor IgM (RF‐IgM) and serum calprotectin (sCP) in pre–rheumatoid arthritis (RA) as well as the diagnostic accuracies of these biomarkers for the timing of diagnosis of future RA.MethodsA total of 215 RA cases, each with approximately three pre‐RA diagnoses and one post–RA diagnosis serum sample, and controls were identified from the Department of Defense Serum Repository. All case samples and a single sample from each control subject were tested for anti‐CCP3 (IgG), RF‐IgM, and sCP. The diagnostic accuracies of biomarkers for future RA were evaluated.ResultsAnti‐CCP3, RF‐IgM, and sCP were elevated in pre‐RA, with anti‐CCP3 and sCP significantly elevated compared with RF‐IgM at the earliest time points. Within the cases, the combination of anti‐CCP3 and RF‐IgM positivity had a positive predictive value (PPV) of 35.6% for a diagnosis of RA in 3 years or less, which is significantly higher than the PPV of 18.7% for anti‐CCP3 positivity alone (P < 0.001). A combination of anti‐CCP3, RF‐IgM, and sCP had the highest PPV (53.0%) for a diagnosis of RA in 3 years or less; however, this was not significantly higher than the PPV for anti‐CCP3 and RF‐IgM positivity (P = 0.248).ConclusionAnti‐CCP3, RF‐IgM, and sCP are elevated in pre‐RA; furthermore, combinations of elevations of these biomarkers are more commonly seen in the period of less than or equal to 3 years to diagnosis. This may be considered in creating inclusion criteria in prevention trials in RA. In addition, the biologic relationships of these biomarkers in pre‐RA need exploration.

IgA rheumatoid factor is associated with bone mineral density preservation in rheumatoid arthritis

Autoantibodies such as IgM rheumatoid factor (RF) and anti-citrullinated proteins/peptides antibodies (ACPA) have previously been incriminated in systemic bone loss in rheumatoid arthritis (RA). There are, however, no data describing association of IgA RF and IgG RF with systemic bone loss. This study was aimed to investigate the association of RF isotypes with systemic bone loss among patients with RA. RF isotypes and ACPA were measured by enzyme-linked immunosorbent assay among 153 patients with RA. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry. Ninety-four (61.4%) patients had positive IgA RF, 89 (58.2%) had positive IgG RF, 109 (71.2%) had positive IgM RF, whereas 122 (80.3%) RA patients tested positive for ACPA. Compared to the IgA RF-negative patients, IgA RF-positive patients exhibited higher disease activity and had higher RF titers. Seven (4.6%) patients had low BMD at femoral neck, 12 (7.8%) at total femur, and 47 (30.7%) at lumbar spine. IgA RF was found to be associated with protection against low BMD at spine (OR = 0.47, 95% CI = 0.23-0.95, p = 0.034). This association was further confirmed in the multivariate regression analysis taking into account several potential confounding factors(OR = 0.21, 95% CI = 0.06-0.65, p = 0.039). No association between low BMD and the presence of IgG RF or IgM RF or ACPA was found. IgA RF for the first time ever was shown to be associated with BMD preservation at spine in RA. Key points • IgA RF was associated with protection against low spinal BMD. • No association between low BMD and the presence of IgG RF or IgM RF was found.

Comparative Analyses of Serological Biomarkers and Disease Characteristics between Elderly-onset and Younger-onset Rheumatoid Arthritis

The onset of rheumatoid arthritis (RA) may occur any time after the age of 16 years. The purpose of this study was to compare the clinical and serological differences between elderly onset RA (EORA); which is begins at the age of 60 and above, with younger onset RA (YORA). A total of 69 EORA and 82 YORA female patients were enrolled in this study. Data on medications, disease duration, age at onset, disease activity at onset and laboratory parameters were collected by reviewing the medical records. All patients had their blood samples taken for serum anticyclic citrulinated peptide (anti-CCP), IgA rheumatoid factor (RF), IgM RF and IgG RF. Besides, the subjects were assessed for their radiographic joint damage based on Modified Sharp Score (MSS) and functional disability based on the Health Assessment Questionnaire-disability Index (HAQ-DI) scores. Despite comparable disease duration and frequency of seropositivity, the YORA group had significantly higher disease activity at onset of the disease (p=0.009). In keeping with this finding, the YORA group had more severe joint damage based on radiographic assessment (MSS scores of 17.49+19.04 versus 10.04+12.79). The YORA group had significantly higher levels of IgA RF and anti-CCP with p-values of 0.035 and 0.002, respectively. Our findings suggest that YORA is associated with more severe disease, worse radiographic joint damage and higher levels of anti-CCP and IgA RF.