Increased Rheumatoid Factor production in patients with severe COVID-19

BACKGROUND

Searching for Rheumatoid Factors (RF) in patients with coronavirus disease (COVID-19) has rarely been described.

OBJECTIVES

To investigate the association between RF isotypes (IgM, IgA, and IgG) and different clinical presentations of COVID-19 in a series of Tunisian patients.

STUDY DESIGN

Eighty-two COVID-19 patients were enrolled in this study. Symptomatic cases were recruited from the Department of COVID-19 and the intensive care unit (ICU) of the University Hospital of Mahdia, Tunisia, from January 2021 to March 2021. Different RF isotypes were assessed using a commercial enzyme-linked immunosorbent assay (ELISA).

RESULTS

Forty-one patients (50%) had RF of any isotype. Thirty-two patients (39%) were tested positive for RF-IgM. Symptomatic forms of the disease were associated with RF-IgM positivity (p = 0.005). The mean concentration of RF-IgM was higher in the severe form than in the moderate and asymptomatic forms (p = 0.006).

CONCLUSIONS

Our study suggests that the production of RF-IgM isotype is increased in patients with severe COVID-19.

Exposure to air pollutants and rheumatoid arthritis biomarkers: A scoping review

INTRODUCTION

Rheumatoid arthritis (RA) is a common autoimmune disease with a complex and poorly understood etiology that includes genetic, hormonal, and environmental factors.

OBJECTIVE

Our objective was to assess current literature that investigated the association between exposure to environmental and occupational air pollutants and RA-related biomarkers rheumatoid factor (RF) and anti-citrullinated peptide antibody (ACPA).

DESIGN

PubMed and Web of Science were used to identify epidemiological studies that measured or estimated air pollution and at least one RA biomarker. Information was charted for comparison of evidence, including pollutant(s) studied, exposure assessment, biomarker measurement, analysis method, study population, size, dates, adjustment variables, and findings.

RESULTS

Several common air pollutants (including two mixtures) and a few dozen occupational inhalants were assessed in 13 eligible studies. Associations between industrial sulfur dioxide and particulate matter less than 2.5 µm in diameter with ACPA were observed most frequently, including associations between residential proximity to pollution sources and ACPA positivity. Consistency of associations with other pollutants was either not observed or limited to single studies. Three studies evaluated the modifying impact of SE alleles (a genetic factor associated with RA) and found that pollutant associations were stronger among participants positive for SE alleles.

CONCLUSION

Based on mixed results, there was no consistent link between any single pollutant and RA-related biomarker outcomes. Comparisons across studies were limited by differences in study populations (e.g., by RA status, by sociodemographic groups) and study design (including designs focused on different sources of air pollution, methodological approaches with varying levels of potential exposure misclassification, and assessments of inconsistent biomarker cut-points). However, given that multiple studies reported associations between exposure to air pollution and RA biomarkers, continued exploration utilizing studies that can be designed with a more robust causal framework, including continued consideration of effect modification by genetic status, may be necessary.

Clinical Utility of Pro-inflammatory Oligomeric Glycoprotein Tenascin-C in the Diagnosis of Seropositive and Seronegative Rheumatoid Arthritis

Owing to limited usefulness of Rheumatoid Factor and anti-CCP in rheumatoid arthritis, there is a need to identify a more sensitive and specific biomarker to detect rheumatoid arthritis (RA), particularly seronegative RA cases. Tenascin-C is an extracellular matrix glycoprotein, which has been implicated in the pathophysiology of RA. The objective of our study was to evaluate the diagnostic utility of serum Tenascin-C in seropositive and seronegative rheumatoid arthritis patients. We conducted a cross-sectional case control study. Sixty patients who fulfilled the ACR 2010 criteria for rheumatoid arthritis were included in the study. Thirty patients were found to be positive for RF and/or anti-CCP and 30 were negative for both RF and anti-CCP. Thirty age and gender-matched healthy subjects were taken as controls. Serum Tenascin-C was measured by quantitative sandwich enzyme immunoassay technique. The mean serum concentration of Tenascin-C in controls, seronegative and seropositive cases was 0.66 ng/ml, 20.54 ng/ml and 23.42 ng/ml, respectively. Tenascin-C levels were significantly higher in RA cases compared to controls (p < 0.0001). There was no significant difference in Tenascin-C between seropositive and seronegative cases (p = 0.603). ROC curve analysis showed a sensitivity of 96.6% and specificity of 100% with AUC of 0.98 at 2.21 ng/ml as cut-off value for diagnosing RA. Tenascin-C is elevated in both seronegative and seropositive RA, which indicates that it can be used as a sensitive marker for RA. The addition of Tenascin-C to the existing RF and anti-CCP may help in identifying a large number of patients with RA, particularly seronegative rheumatoid arthritis cases.

Release of Antibodies and Cytokines from B Cells

Autoreactive B cells play a critical role in rheumatoid arthritis (RA). These cells differentiate into long-living memory B cells and autoantibody-producing plasma cells, and also present autoantigens to T cells to amplify misdirected immune responses. The therapeutic benefit of B-cell-deleting depleting therapies suggests that B cells are emerging as important factors in the pathogenesis of RA. Aiming at evaluation of the function of B cells, which are usually derived from peripheral blood of RA patients and healthy donors, it is possible to conduct a series of experiments, such as in vitro assessment of antibody production and BCR-mediated cytokine release. These techniques can also be applied for in vivo application.

Novel and unique rheumatoid factors cross-react with viral epitopes in COVID-19

Rheumatoid factors (RFs), polyreactive antibodies canonically known to bind two conformational epitopes of IgG Fc, are a hallmark of rheumatoid arthritis but also can arise in other inflammatory conditions and infections. Also, infections may contribute to the development of rheumatoid arthritis and other autoimmune diseases. Recently, RFs only in rheumatoid arthritis were found to bind novel linear IgG epitopes as well as thousands of other rheumatoid arthritis autoantigens. Specific epitopes recognized by infection-induced polyreactive RFs remain undefined but could provide insights into loss of immune tolerance. Here, we identified novel linear IgG epitopes bound by RFs in COVID-19 but not rheumatoid arthritis or other conditions. The main COVID-19 RF was polyreactive, binding two IgG and multiple viral peptides with a tripeptide motif, as well as IgG Fc and SARS-CoV-2 spike proteins. In contrast, a rheumatoid arthritis-specific RF recognized IgG Fc, but not tripeptide motif-containing peptides or spike. Thus, RFs have disease-specific IgG reactivity and distinct polyreactivities that reflect the broader immune response. Moreover, the polyreactivity of a virus-induced RF appears to be attributable to a very short peptide motif. These findings refine our understanding of RFs and provide new insights into how viral infections may contribute to autoimmunity.

A novel highly specific biotinylated MAC-ELISA for detection of anti-SARS-CoV-2 nucleocapsid antigen IgM antibodies during the acute phase of COVID-19

The gold standard for diagnosing COVID-19 in the acute phase is RT-qPCR. However, this molecular technique can yield false-negative results when nasopharyngeal swab collection is not conducted during viremia. To mitigate this challenge, the enzyme-linked immunosorbent assay (ELISA) identifies anti-SARS-CoV-2 IgM antibodies in the initial weeks after symptom onset, facilitating early COVID-19 diagnosis. This study introduces a novel and highly specific IgM antibody capture ELISA (MAC-ELISA), which utilizes biotinylated recombinant SARS-CoV-2 nucleocapsid (N) antigen produced in plants. Our biotinylated approach streamlines the procedure by eliminating the requirement for an anti-N-conjugated antibody, circumventing the need for peroxidase-labeled antigens, and preventing cross-reactivity with IgM autoantibodies such as rheumatoid factor. Performance evaluation of the assay involved assessing sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy using 682 RT-qPCR-positive samples, categorized by weeks relative to symptoms onset. Negative controls included 205 pre-pandemic serum samples and 46 serum samples from patients diagnosed with other diseases. Based on a cut-off of 0.087 and ROC curve analysis, the highest sensitivity of 81.2% was observed in the 8-14 days post-symptom (dps) group (2nd week), followed by sensitivities of 73.8% and 68.37% for the 1-7 dps (1st week) and 15-21 dps groups (3rd week), respectively. Specificity was consistently 100% across all groups. This newly developed biotinylated N-MAC-ELISA offers a more streamlined and cost-effective alternative to molecular diagnostics. It enables simultaneous testing of multiple samples and effectively identifies individuals with false-negative results.

Correlation analysis and clinical significance of Musculoskeletal Ultrasound semi-quantitative grading with bone salt metabolism, Rheumatoid factor and Erythrocyte Sedimentation rate in patients with Rheumatoid Arthritis

Objective

To determine the correlation and clinical significance of musculoskeletal ultrasound semi-quantitative grading with bone salt metabolism, rheumatoid factor and erythrocyte sedimentation rate (ESR) in patients with rheumatoid arthritis.

Methods

This is a clinical comparative study. A total of 240 patients with rheumatoid arthritis admitted to Baoding NO.1 Central Hospital were selected according to the DAS28 score of rheumatoid arthritis, and were divided into four groups, with 60 cases in each group from May 2020 to May 2022. The differences and correlation of musculoskeletal ultrasound semi-quantitative grading, bone metabolism indicators, erythrocyte sedimentation rate and rheumatoid factor among the four groups were statistically analyzed.

Results

The scores of bone erosion, synovial hyperplasia, joint effusion and intrasynovial blood flow in Group-H were significantly higher than those in Group-R, L and M, with statistically significant differences(p=0.00). The procollagen Type-1 N-terminal propeptide(P1NP), bone-specific alkaline phosphatase(BALP) and osteoprotegerin(OPG) in Group-H were significantly lower than those in Group-R, L and M, with statistically significant differences(p=0.00); The tartrate-resistant acid phosphatase(TRAC) in Group-H was significantly higher than that in Group-R, L and M, with a statistically significant difference(p=0.00). The levels of RF and ESR in Group-H were significantly higher than those in Group-R, L and M, with statistically significant differences(p=0.00).

Conclusion

Musculoskeletal ultrasound semi-quantitative grading is correlated with the level of bone salt metabolism, rheumatoid factor and ESR in patients with rheumatoid arthritis. It can be combined with laboratory examination to objectively judge the severity of the course of rheumatoid arthritis.

Biochemical markers and FokI and TaqI vitamin D receptor genes polymorphism in rheumatoid arthritis

BACKGROUND

Previous studies have reported the role of genes in different metabolic processes in the human body, and any variation in gene polymorphisms could lead to disturbances in these processes and different diseases.

OBJECTIVE

This study aimed to compare vitamin D receptor (VDR) FokI and TaqI genotypes in terms of parathyroid hormone (PTH) and some biomarkers of inflammation and susceptibility to rheumatoid arthritis (RA) disease.

METHODS

This study included 100 patients with rheumatoid arthritis (RA). Genotyping was performed by polymerase chain reaction (PCR) and examined by specific restriction enzymes using restriction fragment length polymorphism (RFLP). Serum intact PTH, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), and anti-cyclic citrullinated peptide antibodies (ACCPs) levels were measured.

RESULTS

An increased PTH level (> 65 pg/ml) was found in 8% of patients. No significant differences among FokI and TaqI vitamin D receptor genes polymorphism regarding positive and negative RF or ACCPs were found. A significant difference was found among FokI (p = 0.009) and none in TaqI genotypes regarding intact parathyroid hormone level categories. No significant correlation was found between the serum intact PTH level and ESR or CRP levels (P = 0.13 and 0.28, respectively). The parathyroid hormone level was not a good predictor for RF or ACCPs (P = 0.5 and 0.06, respectively).

CONCLUSION

The FokI gene may play a role in controlling PTH levels in patients with RA. There was no significant correlation found between the serum intact PTH level and RA severity according to ESR and CRP inflammatory biomarkers. There are no differences between VDR genes FokI and TaqI polymorphism in terms of RA susceptibility (for RF and ACCPs).

Filgotinib Modulates Inflammation-Associated Peripheral Blood Protein Biomarkers in Adults with Active Rheumatoid Arthritis and Prior Inadequate Response to Methotrexate

INTRODUCTION

Our aim was to evaluate protein biomarker changes related to the administration of filgotinib, a Janus kinase (JAK) 1 preferential inhibitor, in patients with moderately to severely active rheumatoid arthritis (RA) with inadequate response to methotrexate.

METHODS

Plasma and serum samples were collected from patients enrolled in FINCH 1 (NCT02889796), a Phase 3 trial. Patients with stable backgrounds of methotrexate were randomly assigned once-daily oral filgotinib 200 or 100 mg, subcutaneous adalimumab 40 mg every 2 weeks (W), or placebo. Up to 35 biomarkers were analyzed at baseline, W4, and W12 with enzyme-linked immunosorbent assays and chemiluminescence and electrochemiluminescence assays.

RESULTS

At baseline, four distinct biomarker clusters were identified. The strongest intragroup correlations were in bone-cartilage resorption/inflammation and JAK/signal transducer and activator of transcription (STAT) signaling activity. At baseline, significant positive correlations were identified for cytokines with patient-reported pain and with patient measures of fatigue. Filgotinib reduced levels of cytokines associated with inflammation and cell migration as early as W4 and through W12. Compared to adalimumab, filgotinib induced significant reductions in bone-related turnover biomarkers, N-telopeptide of type 1 collagen and C-telopeptide 1, as well as biomarkers associated with baseline disease activity. No baseline predictors of therapeutic response to filgotinib were identified.

CONCLUSIONS

Filgotinib reduced peripheral protein biomarkers associated with JAK/STAT signaling, inflammatory signaling, immune cell migration, and bone resorption as soon as W4 in FINCH 1. Effects were dose-dependent and consistent with the clinical efficacy of filgotinib observed in FINCH 1. The changes in peripheral biomarkers associated with filgotinib treatment in methotrexate-experienced patients are consistent with changes observed in both methotrexate-naïve and biologic disease-modifying antirheumatic drug-experienced RA populations. These data demonstrate dose-dependent effects of preferential JAK1 inhibition by filgotinib on peripheral blood protein biomarkers in methotrexate-experienced patients with RA.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02889796.

Rheumatic manifestations of hepatitis C virus infection are associated with autoantibodies but not viremia

BACKGROUND

To investigate the associations between extrahepatic manifestations, autoantibodies, and viremia in patients with hepatitis C virus (HCV) infection.

METHODS

This cross-sectional study recruited patients with HCV infection from the outpatient department of a tertiary medical center in Northern Taiwan between January 2017 and August 2019. Autoantibody profiles and the clinical parameters of HCV infection were evaluated using laboratory tests, and a questionnaire was used to record extrahepatic manifestations. HCV infection status, including inactive HCV infection, active hepatitis, and cirrhosis, was defined according to abdominal ultrasonography findings and alanine transaminase levels.

RESULTS

A total of 77 patients with HCV were recruited, with 19.5% and 16.9% of patients, respectively, presenting with arthritis and dry eyes. Autoantibody screening revealed rheumatoid factor (RF), antinuclear antibody (ANA), anti-Ro antibody, and anti-La antibody positivity in 20.8%, 23.4%, 13.0%, and 2.6% of the patients, respectively. The presence of RF was associated with arthritis, whereas the presence of ANA was associated with dry eyes but not dry mouth. Active hepatitis and HCV-related cirrhosis were associated with viremia, but not autoantibody profiles.

CONCLUSION

In this single-center study, the prevalence of extrahepatic manifestations and autoantibodies did not differ in patients stratified by the HCV infection status. Rheumatic manifestations were associated with the presence of autoantibodies but not with viremia.

Benefits of Autoantibody Enrichment in Early Rheumatoid Arthritis: Analysis of Efficacy Outcomes in Four Pooled Abatacept Trials

INTRODUCTION

The efficacy of abatacept is enhanced in anti-citrullinated protein antibody (ACPA) and rheumatoid factor (RF)-positive versus -negative patients with rheumatoid arthritis (RA). Four early RA abatacept trials were analyzed to understand the differential impact of abatacept among patients with SeroPositive Early and Active RA (SPEAR) compared to non-SPEAR patients.

METHODS

Pooled patient-level data from AGREE, AMPLE, AVERT, and AVERT-2 were analyzed. Patients were classified as SPEAR if they were ACPA +, RF +, disease duration < 1 year, and Disease Activity Score-28 (DAS28) C-reactive protein (CRP) ≥ 3.2 at baseline; non-SPEAR otherwise. Outcomes included: American College of Rheumatology (ACR) 20/50/70 at week 24; mean change from baseline to week 24 for DAS28 (CRP), Simple Disease Activity Index (SDAI), ACR core components; DAS28 (CRP) and SDAI remission. Adjusted regression analyses among abatacept-treated patients compared SPEAR and non-SPEAR patients, and in full trial population estimating how the efficacy of abatacept versus comparators [adalimumab + methotrexate, methotrexate] was modified by SPEAR status.

RESULTS

The study included 1400 SPEAR and 673 non-SPEAR patients; most were female (79.35%), white (77.38%), and with a mean age 49.26 (SD 12.86) years old. Around half with non-SPEAR were RF + and three-quarters ACPA +. Stronger improvements from baseline to week 24 were observed in almost all outcomes for abatacept-treated SPEAR versus non-SPEAR patients or versus SPEAR patients treated with comparators. Larger improvements were observed for SPEAR patients among the abatacept-treated population, and more strongly improved efficacy among SPEAR patients for abatacept than comparators.

CONCLUSIONS

This analysis, including large patient numbers of early-RA abatacept trials, confirmed beneficial treatment effects of abatacept in patients with SPEAR versus non-SPEAR.

Falsely decreased vancomycin caused by rheumatoid factor: A case report

BACKGROUND

Vancomycin is associated with potential nephrotoxicity and trough concentrations need to be monitored in certain patients. Falsely decreased vancomycin measurement may result in overtreatment and need to be identified promptly by clinicians and pharmacists to avoid toxicities.

METHODS AND RESULTS

We report a case of rheumatoid factor-mediated falsely low vancomycin measurement with Abbott particle-enhanced turbidimetric inhibition immunoassay (PETINIA) method. Reanalyzing the sample using an alternative method, removing the interferences using heterophile blocking reagent as well as rheumatoid factor clean-up solution all helped to solve the false results. Results from alternative method and interference studies showed vancomycin concentrations reached toxic concentrations in the patient and administration of the drug was immediately terminated. The patient experienced a transient increase in serum creatinine.

CONCLUSIONS

Even though most modern immunoassays use blocking agents to neutralize interfering antibodies such as rheumatoid factor, it is important for health care professionals to understand that occasional interference still occurs due to the heterogeneous nature of rheumatoid factor.

How common is remission in rheumatoid factor-positive juvenile idiopathic arthritis patients? The multicenter Pediatric Rheumatology Academy (PeRA) research group experience

OBJECTIVE

Rheumatoid factor (RF)-positive polyarthritis is the least common type of juvenile idiopathic arthritis (JIA). Functional disability in RF-positive polyarthritis patients is much more severe than in patients with other subtypes; but data on this subtype alone is limited. This study aimed to analyze clinical features, long-term follow-up, treatment response, and remission status in a large multicenter cohort of RF-positive polyarthritis patients.

METHODS

This retrospective study included RF-positive polyarthritis patients that were followed up for ≥ 6 months between 2017 and 2022 by the Pediatric Rheumatology Academy (PeRA)-Research Group (RG). Data on patient demographics, clinical and laboratory characteristics were obtained from medical charts. JIA treatments and duration of treatment were also recorded. The patients were divided into 2 groups based on methotrexate (MTX) response, as follows: group 1: MTX responsive, group 2: MTX unresponsive. Clinical and laboratory findings were compared between the 2 groups.

RESULTS

The study included 56 (45 female and 11 male) patients. The median age at onset of RF-positive polyarthritis was 13.2 years [(interquartile range) (IQR): 9.0-15.0 years] and the median duration of follow-up was 41.5 months (IQR: 19.5-75.7 months). Symmetrical arthritis affecting the metacarpophalangeal and proximal interphalangeal joints of the hands was commonly observed. Subcutaneous MTX was the preferred initial treatment; however, it was ineffective in 39 (69.6%) of the patients. Of 25 patients followed for 24 months, 56% still had active disease at 24 months.

CONCLUSION

During 2 years of treatment, 44% of RF-positive polyarthritis patients have inactive disease, and they should be considered as a distinct and important clinical entity requiring aggressive and early treatment.

Associations of Rheumatoid Factor, Rheumatoid Arthritis, and Interleukin-6 Inhibitor with the Prognosis of Ischemic Stroke: a Prospective Multicenter Cohort Study and Mendelian Randomization Analysis

Rheumatoid factor (RF), an established diagnostic biomarker for rheumatoid arthritis (RA), is associated with cardiovascular diseases, but its impact on clinical outcomes of ischemic stroke remains unclear. We aimed to investigate the observational associations between serum RF and prognosis of ischemic stroke, and further examined the genetic associations of RA and its therapeutic strategy, interleukin-6 (IL-6) inhibitor, with prognosis of ischemic stroke. We measured serum RF levels in 3474 Chinese ischemic stroke patients from the China Antihypertensive Trial in Acute Ischemic Stroke. The primary outcome was the composite outcome of death or major disability (modified Rankin Scale score ≥3) at 3 months after stroke onset. Mendelian randomization (MR) analyses were performed to examine the associations of genetically predicted RA and IL-6 inhibition with prognosis of ischemic stroke. During 3 months of follow-up, 866 patients (25.43%) experienced death or major disability. After multivariate adjustment, RF-positive was significantly associated with a high risk of primary outcome (OR, 1.47; 95% CI, 1.08-2.00; P =0.016) compared with RF-negative. The two-sample MR analyses suggested that genetically predicted RA was associated with an increased risk of primary outcome (OR, 1.09; 95% CI, 1.01-1.18; P=0.021), while genetically predicted IL-6 inhibition was associated with a decreased risk of primary outcome (OR, 0.88; 95% CI, 0.77-0.99; P=0.041). We found that positive RF was associated with increased risks of adverse outcomes after atherosclerotic ischemic stroke, and genetically predicted RA and IL-6 inhibition increased and decreased the risks of adverse outcomes after ischemic stroke, respectively.

Serological markers of rheumatoid arthritis in patients with primary biliary cholangitis and the vice versa: A Tunisian study

BACKGROUND

Primary biliary cholangitis (PBC) is an autoimmune disease of the liver characterized by destructive lymphocytic cholangitis and anti-mitochondrial antibodies (AMA). Anti-gp210 and anti-Sp100, are used for the diagnosis of PBC in AMA-negative PBC patients. Patients with PBC have a propensity to have an extrahepatic manifestation which is especially autoimmune.

OBJECTIVE

We aimed to determine the frequency of serological markers of rheumatoid arthritis (RA) (CCP-Ab or RF) in PBC patients and to do the vice versa.

METHODS

Our PBC study included 70 patients with PBC and 80 healthy blood donors (HBD) and our RA study included 75 patients with RA and 75 HBD. Anti-cyclic citrullinated peptide antibodies (CCP-Ab) and rheumatoid factor (RF) were performed by indirect ELISA. AMA, anti-Sp100 and anti-gp210 were determined by indirect immunofluorescence.

RESULTS

RA autoantibodies (CCP-Ab or RF) were more frequent in PBC patients than in HBD (65.7% vs. 8.7% p 〈10^-6). CCP-Ab were significantly more frequent in patients than in controls (15.7% vs. 2.5%; p = 0.004). Nine patients had both CCP-Ab and RF vs. none of controls (12.8% vs. 0%; p = 0.001). RF were detected in 45 patients with PBC and in 5 HBD (64.3% vs. 6.2%; p 〈10^-6). In PBC patients, RF were more frequent than CCP-Ab (64.3% vs. 15.7%; p 〈10^-6). RF-IgG were present in 18.5% of patients; RF-immunoglobulin (Ig) A in 34.3% and RF-IgM in 54.3%. These frequencies were significantly higher than those found in control group (1.2% for RF-IgG (p 〈10^-3); 0% for RF-IgA (p 〈10^-6); and 6.2% for RF-IgM (p 〈10^-6)). In our PBC patients, RF-IgA were more frequent than RF-IgG (34.3% vs. 18.5%; p = 0.03) and than CCP-Ab (34.3% vs. 15.7%; p = 0.01). Six patients had only RF-IgA versus none of the control group (8.6% vs. 0%; p = 0.01). AMA, anti-Sp100 and anti-gp 210 were absent in all RA patients.

CONCLUSIONS

Serological markers of RA were more frequent in PBC patients than in HBD and the vice versa was not true.

Serum antibodies to periodontal pathogens prior to rheumatoid arthritis diagnosis: A case-control study

OBJECTIVES

1) To quantify the association between anti-Porphyromonas gingivalis serum antibody concentrations and the risk of developing rheumatoid arthritis (RA), and 2) to quantify the associations among RA cases between anti-P. gingivalis serum antibody concentrations and RA-specific autoantibodies. Additional anti-bacterial antibodies evaluated included anti-Fusobacterium nucleatum and anti-Prevotella intermedia.

METHODS

Serum samples were acquired pre- and post- RA diagnosis from the U.S. Department of Defense Serum Repository (n = 214 cases, 210 matched controls). Using separate mixed-models, the timing of elevations of anti-P. gingivalis, anti-P. intermedia, and anti-F. nucleatum antibody concentrations relative to RA diagnosis were compared in RA cases versus controls. Associations were determined between serum anti-CCP2, ACPA fine specificities (vimentin, histone, and alpha-enolase), and IgA, IgG, and IgM RF in pre-RA diagnosis samples and anti-bacterial antibodies using mixed-effects linear regression models.

RESULTS

No compelling evidence of case-control divergence in serum anti-P. gingivalis, anti-F. nucleatum, and anti-P. intermedia was observed. Among RA cases, including all pre-diagnosis serum samples, anti-P. intermedia was significantly positively associated with anti-CCP2, ACPA fine specificities targeting vimentin, histone, alpha-enolase, and IgA RF (p<0.001), IgG RF (p = 0.049), and IgM RF (p = 0.004), while anti-P. gingivalis and anti-F. nucleatum were not.

CONCLUSIONS

No longitudinal elevations of anti-bacterial serum antibody concentrations were observed in RA patients prior to RA diagnosis compared to controls. However, anti-P. intermedia displayed significant associations with RA autoantibody concentrations prior to RA diagnosis, suggesting a potential role of this organism in progression towards clinically-detectable RA.

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

BACKGROUND

The 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).

METHODS

Clinical 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.

RESULTS

The 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.

CONCLUSION

We 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.

Risk stratification using anti-citrullinated peptide antibodies (ACPA) in polyarticular subtypes of juvenile idiopathic arthritis in adulthood

OBJECTIVES

Polyarticular juvenile idiopathic arthritis (pJIA) is a subset of juvenile idiopathic arthritis (JIA), divided into two subtypes according to the presence of rheumatoid factor: pJIA without rheumatoid factor (pJIA RF-) and pJIA with positive rheumatoid factor (pJIA RF+), this latter is characterised with more structural damage. Anti-citrullinated peptide antibodies (ACPA) are often associated with RF. The respective performance of ACPA versus RF in structural outcome in pJIA, and in particular in adulthood pJIA remains unknown. Therefore, the aim of this study was to determine whether ACPA could be of value to assess structural damage in pJIA persisting in adulthood.

METHODS

Patients with pJIA and available data for ACPA, RF and X-ray were included retrospectively. Structural damage was assessed by two independent blinded investigators using Sharp Van Der Heijde scores.

RESULTS

56 pJIA adult patients were included: 62% (35/56) had pJIA RF+ and 38% (21/56) pJIA RF-. ACPA positivity in pJIA was significantly associated with presence of RF (96% vs 26%, P<0.001). RF positivity was significantly associated with higher Sharp van Der Heijde erosion and total scores (respectively P<0.01 and P<0.05). There were higher Sharp Van Der Heijde erosion, joint space narrowing and total scores in the pJIA ACPA+ subgroup than in the pJIA ACPA- subgroup, although there was no statistical significance. However, when adjusted on disease duration, pJIA ACPA+ patients had significantly higher erosion and total scores than pJIA ACPA- patients (P<0.05), and pJIA ACPA+ patients required more bDMARDs than pJIA ACPA- patients (P<0.05). Moreover, pJIA patients with high Sharp van Der Heijde joint space narrowing and total scores had significantly higher ACPA levels (P<0.01). A correlation was identified between ACPA levels and Sharp van Der Heijde total score (r=0.54, P<0.05). In the pJIA RF+ subgroup the presence of ACPA was associated with additional structural damage compared to no ACPA: sharp Van Der Heijde erosion, joint space narrowing and total scores were higher in the pJIA RF+ ACPA+ subgroup than in the pJIA RF+ ACPA- subgroup although these results did not reach significance.

CONCLUSION

Our results suggest that pJIA RF+ ACPA+ adult patients may have a more severe articular phenotype than pJIA RF+ ACPA- patients. ACPA could bring an additional value to RF for pJIA patients regarding structural damage. Altogether our results show that RF and ACPA are associated with structural damage measured by Sharp Van Der Heijde score in pJIA persisting in adulthood.

Autoimmune markers and vascular immune deposits in Finkelstein-Seidlmayer vasculitis: Systematic literature review

Finkelstein-Seidlmayer vasculitis, also called acute hemorrhagic edema of young children or infantile immunoglobulin A vasculitis, is habitually a benign skin-limited small vessel leukocytoclastic vasculitis that mainly affects infants 24 months or less of age. Since this disease is commonly triggered by an infection, an immune-mediated origin has been postulated. To better appreciate the possible underlying immune mechanism of this vasculitis, we addressed circulating autoimmune markers and vascular immune deposits in patients contained in the Acute Hemorrhagic Edema BIbliographic Database, which incorporates all original reports on Finkelstein-Seidlmayer vasculitis. A test for at least one circulating autoimmune marker or a vascular immune deposit was performed in 243 cases. Subunits of complement system C4 resulted pathologically reduced in 4.7% and C3 in 1.4%, rheumatoid factor was detected in 6.1%, and antinuclear antibodies in 1.9% of cases. Antineutrophil cytoplasmic antibodies were never demonstrated. Immunofluorescence studies were performed on 125 skin biopsy specimens and resulted positive for complement subunits in 46%, fibrinogen in 45%, immunoglobulin A in 25%, immunoglobulin M in 24%, immunoglobulin G in 13%, and immunoglobulin E in 4.2% of cases. Infants testing positive for vascular immunoglobulin A deposits did not present a higher prevalence of systemic involvement or recurrences, nor a longer disease duration. In conclusion, we detected a very low prevalence of circulating autoimmune marker positivity in Finkelstein-Seidlmayer patients. Available immunofluorescence data support the notion that immune factors play a relevant role in this vasculitis. Furthermore, vascular immunoglobulin A deposits seem not to play a crucial role in this disease.

Ultrasound tenosynovitis: A differential feature of patients with seronegative rheumatoid arthritis

OBJECTIVE

To identify differential features between patients with seropositive and seronegative rheumatoid arthritis (RA).

METHOD

Prospective cohort study, including patients who were admitted for polyarthralgia. At baseline was performed: laboratory studies, X-rays of hands and feet, ultrasound of both hands with power Doppler technique, clinical data and clinimetry. In subsequent visits the definitive diagnosis of RA was established or not. It was considered as seronegative RA when patients were negative for both RF and ACPAs.

RESULTS

746 patients were included, of which 128 (17.1%) ended with a final diagnosis of RA. Of these 128 patients, 87 (67.9%) were seropositive RA, while 41 (32%) were seronegative RA. The only feature that showed significant differences was the presence of tenosynovitis detected by ultrasound with a positive power Doppler signal, 13.7% of the patients with seropositive RA vs 41.6% of the patients with seronegative RA (p=0.0028).

CONCLUSION

The only differential feature of patients with seronegative RA was the higher proportion of tenosynovitis detected by ultrasound.

Role of Liquid Biopsies in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease caused by genetic and environmental factors. Early diagnosis is crucial for effective therapy and prognosis of RA, while biomarkers play important roles in early diagnosis. Traditional laboratory tests include rheumatoid factor, anti-cyclic citrullinated peptide antibody, which are inadequate in the ability of early diagnosis. Liquid biopsy technology is a technique using biomarkers found in the blood, urine, and other biological samples from patients, including DNA, RNA, exosome, etc. Evidence indicates that these biomarkers are involved in pathological and physiological conditions of RA. We reviewed the effects of liquid biopsy technology in the early diagnosis of RA and may provide new ideas for effective and precise treatment.

Polyautoimmunity in systemic lupus erythematosus: secondary Sjogren syndrome

BACKGROUND

Sjogren's syndrome (SS) is a chronic autoimmune disease characterized by lymphocytic infiltration of the exocrine glands. It can be associated with other connective tissue diseases, including systemic lupus erythematosus (SLE).

OBJECTIVE

This study aimed to determine the incidence of secondary SS (sSS) in patients diagnosed with SLE (SLE-SS) and compare the clinical and serological features of SLE-SS to SLE only.

METHODS

A retrospective observational study including patients diagnosed with SLE (SLICC criteria) seen at the Rheumatology Department between 1990 and 2020 was performed. A total of 453 SLE patients were assessed for fulfilment of the criteria for SS using the European questionnaire and Schirmer test, fluorescein staining/non-stimulated whole-salivary flow, anti-Ro/La antibodies, and lip biopsy. Anti-Ro/SSA and anti-La/SSB antibodies and rheumatoid factor (RF) were measured at entry and at SS assessment. SLE-SS was defined according to the American-European Consensus Criteria (AECC). SLE-SS was defined as a case that initially only fulfilled SLE classification criteria but which exhibited disease progression during follow-up and then met classification criteria for sSS.

RESULTS

SLE-SS occurred in 11% of the SLE patients. In comparison to SLE-only patients, the SLE-SS group was older at inclusion and onset, and had a longer disease course. Sicca syndrome, oral ulcers, pulmonary involvement, and peripheral neuropathy were more frequent. Anti-SSA, anti-SSB, RF, and total IgG were higher in the SLE-SS group.

CONCLUSION

SLE-SS appears to be a subgroup of patients with distinct clinical and serologic features. The frequency of SLE-SS increases with age. Patients with SLE-SS have a higher frequency of oral ulcers, anti-Ro and anti-La antibodies, and a lower frequency of renal disease, anti-dsDNA antibodies, anti-SM, and lower C3 and C4 hypocomplementemia.

Anti-drug antibodies and rheumatoid factor level in patients with rheumatoid arthritis using the infliximab biosimilar CT-P13

BACKGROUND

This study evaluated the existence of anti-drug antibodies (ADAs) before and 52 weeks after switching from intravenous infliximab (IFX) to intravenous CT-P13 in patients with rheumatoid arthritis (RA).

METHODS

We performed a prospective observational study. Twenty-eight patients (7 males and 21 females) received intravenous CT-P13 after intravenous IFX, and the clinical data were collected from medical records. Rheumatoid factor (RF) and anti-CCP antibody were examined at baseline. At baseline and 52 weeks after the start of CT-P13 treatment, the Disease Activity Score based on the 28-joint count and the levels of C-reactive protein, matrix metalloproteinase-3, and ADA, as well as the erythrocyte sedimentation rate were evaluated. ADAs were measured using an enzyme-linked immunosorbent assay kit.

RESULTS

Seven (25%) and 6 (21.4%) cases were positive for ADAs at baseline and 52 weeks after, respectively. One case became newly positive for ADAs at week 52. Two of the ADA-positive cases became ADA-negative 52 weeks after. The ADA-positive group showed significantly higher RF values at baseline than the ADA-negative group (p = 0.03). No difference was observed between the ADA-positive group and the ADA-negative group regarding other clinical parameters.

CONCLUSIONS

The positive rate of ADAs did not increase after switching from intravenous IFX to intravenous CT-P13. Among the patients with ADAs, a high level of RF was observed at baseline.

Association between rheumatoid factor and metabolic syndrome in general population

BACKGROUND

Rheumatoid arthritis, metabolic syndrome (MS) and cardiovascular disease (CVD) are mutually connected. We aim to investigate the association between rheumatoid factor (RF) and MS in general population, explore the potential value of RF for assessment of metabolic status, and further provide a reference to the establishment of CVD primary prevention for this population.

METHODS

We assessed the health check-up subjects, accordance with the inclusive criteria, from 1 January 2015 to 31 October 2021 in a large refereed general hospital, in this retrospective study. Subjects were categorized into four groups according to their levels of RF. Multivariate logistic regression models along with the Odds ratio (OR) and Confidence interval (CI) values were used to measure the association between RF and MS.

RESULTS

A total of 13,690 subjects were analyzed. Prevalence of MS increased with RF level (P for trend < 0.001). Logistic regression analysis showed that, after adjusting for multiple covariates, RF level was significantly associated with MS prevalence (highest RF quartile: OR, 1.420; 95% CI 1.275,1.581, according to the revised National Cholesterol Education Program Adult Treatment Panel III criteria; OR, 2.355; 95% CI 2.085,2.660, according to the International Diabetes Federation criteria) (both P for trends < 0.001). Among the MS components, there were evidence of increasing trends for overweight/obesity (highest RF quartile: OR, 3.165; 95% CI 2.827,3.543) and hypertension (highest RF quartile: OR, 1.722; 95% CI 1.549,1.914) (both P for trends < 0.001), but decreasing trend for low high-density lipoprotein-cholesterol (highest RF quartile: OR, 0.245; 95% CI 0.214,0.281) (P for trend < 0.001), with increasing RF quartiles.

CONCLUSIONS

RF level is associated with MS prevalence in general population. RF might be a valuable biomarker for assessment of metabolic status in this population. We should be aware of the cardiovascular risk for the higher-RF subjects.

The diagnostic utility of rheumatoid factor and anticitrullinated protein antibody for rheumatoid arthritis in the Indian population

Background

There is lack of Indian data on diagnostic utility of rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) for diagnosis of rheumatoid arthritis (RA) and prevalence of these antibodies in patients with RA and the healthy population. The study was aimed to assess the diagnostic utility and prevalence of RF and ACPA at different titers in the Indian scenario.

Method

All the patients of RA fulfilling the European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) 2010 classification criteria and age and gender-matched healthy controls were included in the study. RF and ACPA were measured by nephelometry and the enzyme-linked immunosorbent assay (ELISA) method, respectively.

Result

Of 803 patients (291 men and 512 women) included, the RF was positive in 566 (70.5%) study patients. The ACPA was positive in 527 (71.7%) patients of 735 of them. Among 408 healthy controls, 45 (11%) were RF positive and 19 (4.7%) were ACPA positive.At the positive cutoff level, the RF had a specificity of 87.6% (95% confidence interval [CI] = 84.4-90.8; positive likelihood ratio [LR+] 5.7). Specificity at 2 and 3 times above the upper limit of normal (ULN) increased to 96.2% (95% CI = 94.3-98.1; LR+ 15.7) and 97.1% (95% CI = 95.5-98.7; LR+ 17.1), respectively.The specificity of ACPA at the positive cutoff level was 94.4% (95% CI = 92.2-96.6; LR+ 12.7), which increased to 98% (95% CI = 96.6-99.4), at 2xULN level. The likelihood ratio for ACPA at all cutoff levels measured was more than 10.

Conclusion

The sensitivity and specificity of RF and ACPA in our study population are comparable with those of other studies. ACPA at lower titers may have sufficient diagnostic utility for RA in an appropriate clinical setting.

Investigation of the association between coffee and risk of RA-results from the Swedish EIRA study

BACKGROUND

Studies on the association between coffee, a modifiable lifestyle factor, and rheumatoid arthritis (RA), a chronic autoimmune disease primarily affecting the joints, have been conflicting. The aim of the present study was to study the association between coffee consumption and risk of RA in the context of different lifestyle factors.

METHODS

We included 2184 cases (72% women, mean age 55 years) newly diagnosed with RA during 2005-2018 in Sweden and 4201 controls matched on age, sex, and residential area. Data on coffee consumption was collected through a food frequency questionnaire and categorized into < 2 (reference), 2-< 4, 4-< 6, and ≥ 6 cups/day. We calculated odds ratios (OR) with 95% confidence intervals (CI) for coffee consumption and risk of RA, in a crude model (taking matching factors into account), and then adjusted first for smoking and further for BMI, educational level, alcohol consumption, and physical activity. We also stratified analyses on sex, smoking, rheumatoid factor, and anti-CCP2 status.

RESULTS

In the crude model, high coffee consumption was associated with increased risk of RA (OR = 1.50, 95% CI 1.20-1.88 for ≥ 6 cups/day compared to < 2 cups). After adjusting for smoking, the OR decreased and was no longer statistically significant (OR = 1.16, 95% CI 0.92-1.46) and decreased further in the full model (OR = 1.14 95% CI 0.89-1.45). This pattern held true in all strata.

CONCLUSION

The findings from this large, population-based case-control study did not support a significant association between coffee consumption and risk of RA as a whole nor within different subgroups.

Periodontal Treatment for Chronic Periodontitis With Rheumatoid Arthritis

BACKGROUND

History of rheumatoid arthritis (RA) increases risk of periodontal diseases. A pro-inflammatory condition noted in periodontitis is considered a trigger for RA. Thus, periodontal treatment aimed at attenuating the pro-inflammatory state could aid in potentially reducing the risk of RA.

AIMS

The objective of this research was to assess the effect of periodontal therapy on rheumatoid factor, Disease Activity Score-28, anti-citrullinated protein antibody, and C-reactive protein levels in patients with chronic periodontitis (CP) and RA.

MATERIALS AND METHODS

The sample consisted of 28 patients with CP and RA. The study was designed to be a double-blind, randomised controlled clinical study. The samples were randomly categorised to either the treatment group (n = 13) or the control group (n = 15). CP status (plaque index, bleeding on probing, probing pocket depth, clinical attachment loss), clinical rheumatologic status (Disease Activity Score), and biochemical status (C-reactive protein, anti-citrullinated protein antibody, and rheumatoid factor) were assessed at baseline and at follow-up at 8 to 12 weeks.

RESULTS

The treatment group showed a highly statistically significant reduction in bleeding on probing (P < .005), probing pocket depth (P < .001), plaque index (P < .001), and C-reactive protein (P < .001); a gain in the clinical attachment loss (P < .001) and an improvement in Disease Activity Score-28 (P = .001) were observed at reassessment following nonsurgical periodontal treatment as compared to the control group. However, blood serum anti-citrullinated protein antibody (P = .002) and rheumatoid factor levels (P = .351) were found to increase from baseline to 8 to 12 weeks following subgingival scaling and root planing.

CONCLUSIONS

Reduction of inflammation in the periodontium by nonsurgical periodontal therapy did not reduce anti-citrullinated protein antibody and rheumatoid factor levels. However, it has shown improvement in periodontal conditions, and remarkable changes were observed in the clinical Disease Activity Score and C-reactive protein levels of individuals with RA.

Rheumatoid Arthritis: Early Diagnosis and Treatment

Rheumatoid arthritis (RA) is a chronic, progressive inflammatory disorder that manifests as a symmetric polyarthritis of small and large joints that may lead to joint and periarticular structural damage and the consequences of systemic inflammation. This overview of early RA examines the unmet needs and challenges in RA, how to best diagnose RA, and pitfalls in early diagnosis and treatment. The rules for referral to a rheumatologist are reviewed. Primary care physicians are at the front line of early diagnosis and need to start disease-modifying therapy as soon as a diagnosis of RA is established.

Differential efficacy of TNF inhibitors with or without the immunoglobulin fragment crystallizable (Fc) portion in rheumatoid arthritis: the ANSWER cohort study

Rheumatoid factor (RF) binds to the fragment crystallizable (Fc) portion of immunoglobulin. It could bind to the Fc portion of anti-TNF inhibitors (TNFi) and attenuate the clinical efficacy. We tried to determine whether the therapeutic efficacy of TNFi with Fc might be lower than that of TNFi without Fc in rheumatoid arthritis (RA) patients with high titres of RF. The Kansai Consortium for Well-being of Rheumatic Disease Patients (ANSWER) cohort is an observational multi-center registry of patients with RA in the Kansai district of Japan. RA patients treated with TNFi were included and divided into two groups based on the structural characteristics between TNFi with Fc (infliximab, adalimumab, golimumab, and etanercept) and TNFi without Fc (certolizumab pegol). Patients were classified into 4 groups according to RF titre quartiles. The sequential disease activity score in 28 joints using erythrocyte sedimentation rate (DAS28-ESR) was compared by Mann-Whitney U test between TNFi with and without Fc in each RF titre group. Multiple linear regression analysis was used to analyze the effect of TNFi without Fc for the change of DAS28-ESR adjusted after potential confounders. A total of 705 RA patients were classified into four groups (RF¹; RF 0-15.0 IU/mL, RF²; 15.0-55.0, RF³; 55.0-166, RF⁴; 166-7555). In RF⁴, RA patients treated with TNFi without Fc had a significantly lower DAS28-ESR than those treated with TNFi with Fc [3.2 (2.3-4.2) vs. 2.7 (2.0-3.0)] after 12 months. This effect of TNFi without Fc for the change of DAS28-ESR after 12 months treatment retained in multivariate analysis in RF⁴. TNFi without Fc may be more efficacious than TNFi with Fc in RA patients with high RF titres.

Impact of autoimmune serology test results on RA classification and diagnosis

Rheumatoid arthritis (RA) is the most common systemic autoimmune disease and also the most severe arthritic disorder. The measurement of rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) in serum supports the diagnosis of RA, which gained increasing significance over the last 65 years. However, a high variability between RF and ACPA methods has been described, impacting the diagnostic performance of the current ACR/EULAR RA classification criteria.

The great number of commercially available assays, often lacking traceability to an international standard, is a major factor attributing to this in-between assay variability. The adoption of an international standard for ACPA, as is since long available for rheumatoid factor, is therefore highly desirable.

Further harmonization in clinical interpretation of RF/ACPA assays could be obtained by harmonization of the cut-offs, for both the low and high antibody levels, based on predefined specificity in disease controls. Reporting test result specific likelihood ratios (LR) adds value in the interpretation of autoantibody tests. However, a good understanding of the control population used to define antibody test result interval-associated LRs is crucial in defining the diagnostic performance characteristics of antibody serology.

Finally, specificity in RA classification can be improved by refining serological weight scoring taking into account the nature of the antibody, the antibody level and double RF + ACPA positivity.

Serum rheumatoid factor IgA, anti-citrullinated peptide antibodies with secretory components, and anti-carbamylated protein antibodies associate with interstitial lung disease in rheumatoid arthritis

Objective

Rheumatoid arthritis (RA) is often complicated with chronic lung diseases (CLD), including interstitial lung disease (ILD) and airway disease, which occur as extra-articular manifestations. CLD in RA have been associated with the production of rheumatoid factor (RF), anti-citrullinated peptide antibody (ACPA), or anti-carbamylated protein (CarP) antibody. However, few validation studies have been performed thus far. In the present study, we investigated the association of RF, ACPA, and anti-CarP antibodies with RA complicated with CLD.

Methods

Sera from RA patients with or without CLD were collected. The levels of serum RF, RF immunoglobulin A (IgA), ACPA IgG, ACPA IgA, and ACPA secretory component (SC) were measured using enzyme-linked immunosorbent assay.

Results

The comparison of RA patients with and without CLD showed that RF IgA was associated with ILD (mean ± standard deviation: 206.6 ± 400.5 vs. 95.0 ± 523.1 U/ml, respectively, P = 1.13 × 10^− 8), particularly usual interstitial pneumonia (UIP) (263.5 ± 502.0 U/ml, P = 1.00 × 10^− 7). ACPA SC was associated with RA complicated with ILD (mean ± standard deviation: 8.6 ± 25.1 vs. 2.3 ± 3.4 U/ml, respectively, P = 0.0003), particularly nonspecific interstitial pneumonia (NSIP) (10.7 ± 31.5 U/ml, P = 0.0017). Anti-CarP antibodies were associated with RA complicated with ILD (0.042 ± 0.285 vs. 0.003 ± 0.011 U/ml, respectively, P = 1.04X10^− 11).

Conclusion

RF IgA and ACPA SC in RA were associated with UIP and NSIP, respectively, suggesting different specificities in patients with RA. Anti-CarP antibodies were associated with ILD in RA. These results may help elucidate the different pathogeneses of UIP and NSIP in RA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04985-0.

Erosive arthritis autoantibodies in systemic sclerosis

OBJECTIVE

We aimed to evaluate in two large SSc French cohorts the prevalence and associated factors with the autoantibodies linked to erosive arthritis.

METHODS

448 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.

RESULTS

RF 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).

CONCLUSION

We 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.

Anti-cyclic citrullinated peptide antibody (ACPA) and Rheumatoid arthritis: Clinical relevance

Rheumatoid Arthritis (RA) is the most common auto-immune, chronic inflammatory joint disease. Predominantly a musculoskeletal condition with a wide spectrum of skeletal and extra-skeletal manifestations, RA has a significant footfall in orthopaedic clinical practice worldwide. RA is essentially a clinical diagnosis; however, laboratory and radiographic investigations can provide complementary diagnostic and prognostic information about the disease. Early diagnosis and initiation of appropriate management are crucial since RA patients can develop chronic, erosive arthritis if left untreated or if treatment is delayed. Rheumatoid Factor (RF) antibody test is routinely employed for diagnostic purposes in patients with suspected RA. However, RF is present only in 70%-80% of patients with RA and can be non-specific. Therefore, Anti-cyclic citrullinated peptide antibody (ACPA), a novel immunological marker for RA is increasingly being utilised to provide higher specificity and a better prognostic indicator in RA patients. We describe the immunological basis of ACPA test and highlight its current applications in the diagnosis, prognosis and monitoring of RA in clinical practice.

Fluorescence-encoded poly(methyl metharcylate) nanoparticles for a lateral flow assay detecting IgM autoantibodies in rheumatoid arthritis

Rheumatoid arthritis (RA) belongs to the most often occurring autoimmune diseases in the world. For serological diagnosis, IgM auto-antibodies directed against the Fc portion of IgG referred to as rheumatoid factor are used as biomarkers. The autoantibody detection is usually done by ELISA. Such assays are reliable but are not suitable for point-of-care testing in contrast to lateral flow assays. Here, we report the development of a lateral flow assay based on carboxylated fluorescence-encoded poly(methyl methacrylate) nanoparticles. Poly(methyl methacrylate) is a non-toxic plastic with an excellent biocompatibility and high optical transparency which promises especially high sensitive fluorescence detection thereby leading to very sensitive assays. We could detect a positive signal in samples with a nephelometric reading down to 0.4 U/mL. By analyzing 30 sera of patients with a RA diagnosis and 34 sera of healthy test subjects we could confirm positive ELISA results in 72% of all cases and negative ELISA results in 97% of all cases.

The citrullinated/native index of autoantibodies against hnRNP-DL predicts an individual "window of treatment success" in RA patients

BACKGROUND

There is a need for biomarker to identify patients "at risk" for rheumatoid arthritis (risk-RA) and to better predict the therapeutic response and in this study we tested the hypothesis that novel native and citrullinated heterogeneous nuclear ribonucleoprotein (hnRNP)-DL autoantibodies could be possible biomarkers.

METHODS

Using protein macroarray and ELISA, epitope recognition against hnRNP-DL was analysed in sera from different developed RA disease and diagnosed SLE patients. Toll-like receptor (TLR) 7/9 and myeloid differentiation primary response gene 88 (MyD88)-dependency were studied in sera from murine disease models. HnRNP-DL expression in cultivated cells and synovial tissue was analysed by indirect immunofluorescence, immunoblot and immunohistochemistry.

RESULTS

HnRNP-DL was highly expressed in stress granules, citrullinated in the rheumatoid joint and targeted by autoantibodies either as native or citrullinated proteins in patient subsets with different developed RA disease. Structural citrullination dependent epitopes (SCEs) of hnRNP-DL were detected in 58% of the SLE patients although 98% of these sera were α-CCP-2-negative. To obtain a specific citrullinated signal value, we subtracted the native antibody value from the citrullinated signal. The citrullinated/native index of autoantibodies against hnRNP-DL (CNDL-Index) was identified as a new value for an "individual window of treatment success" in early RA and for the detection of RF IgM/α-CCP-2 seronegative RA patients (24-46%). Negative CNDL-index was found in SLE patients, risk-RA and early RA cohorts such as EIRA where the majority of these patients are DAS28-responders to methotrexate (MTX) treatment (87%). High positive CNDL-values were associated with more severe RA, shared epitope and parenchymal changes in the lung. Specifically, native α-hnRNP-DL is TLR7/9-dependent, associated with pain and ROC analysis revealed an association to initial MTX or etanercept treatment response, especially in seronegative RA patients.

CONCLUSION

CNDL-index defines people at risk to develop RA and the "window of treatment success" thereby closing the sensitivity gap in RA.

Cryoglobulins: Identification, classification, and novel biomarkers of mysterious proteins

Cryoglobulins consist of serum immunoglobulins that precipitate below 37°C and resolubilize upon warming. The clinical triad of cryoglobulinemia usually includes purpura, weakness, and arthralgia. Cryoglobulinemic syndrome, clinically defined as a systemic vasculitis, is associated with chronic infection with hepatitis C virus (HCV) and autoimmune disorders and can evolve into B-cell malignancies. While the current literature about HCV-associated cryoglobulinemia is not very limited, little is known about the immunologic and serologic profiles of affected patients. Therefore, comprehension of the pathogenetic mechanisms underlying cryoprecipitation could be very helpful. Due to the persistence of viral antigenic stimulation, biomarkers to use after the worsening progression of HCV infection to lymphoproliferative and/or autoimmune diseases are widely needed. Laboratory methods used to detect and characterize low concentrations of cryoprecipitates and immunotyping patterns could improve patient management. The most critical factor affecting cryoglobulin testing is that the pre-analytical phase is not fully completed at 37°C.

Large joints are progressively involved in rheumatoid arthritis irrespective of rheumatoid factor status-results from the early rheumatoid arthritis study

This study aimed to examine the progression of large joint involvement from early to established RA in terms of range of movement (ROM) and time to joint surgery, according to the presence of rheumatoid factor (RF). We used a historical longitudinal cohort of early RA patients. Patients were deemed RF negative if all repeated assessments were negative. The rate of progression from normal to any loss of range of movement (ROM) from years 3 to 14 were modelled using generalized estimating equations, for elbows, wrists, hips, knees and ankle, adjusting for confounders. Time to joint surgery was analysed using multivariable Cox models. A total of 1458 patients were included (66% female, mean age 55 years) and 74% were RF-positive. The prevalence of any loss of ROM, from year 3 through to 14 was highest in the wrist followed by ankle, knee, elbow and hip. Odds of loss of ROM increased over time in all joint regions assessed, at around 7–13% per year from year 3 to 14. Time to surgery was similar according to RF-status for the wrist and ankle, but RF-positive cases had a lower hazard of surgery at the elbow (HR 0.37, 0.15–0.90), hip (HR 0.69, 0.48–0.99) and after 10 years at the knee (HR 0.41, 0.25–0.68). Large joints become progressively involved in RA, most frequently affecting the wrist followed by ankle, which is overlooked in composite disease activity indices. RF-negative and positive cases progressed similarly. Treat-to-target approaches should be followed irrespective of RF status.

Amelioration of autoimmunity and inflammation by zinc oxide nanoparticles in experimental rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects the lining of the synovial joints and approximately affects 0.5 - 1% of the total population imposing a socioeconomic burden. The current study aimed at investigating the novel possible beneficial effects of using zinc oxide nanoparticles (ZnO NPs) on such devastating disease. The complete Freund's adjuvant (CFA) model was used to mimic RA in rats where ZnO NPs were given orally (2 mg/kg/day) daily for 14 days; and diclofenac Na, the standard drug, was given intraperitoneally (1 mg/kg/day) the day after CFA, daily for 14 days. Our results displayed that ZnO NPs attenuated adjuvant-induced increased production of inflammatory mediators interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), interleukin-10 (IL-10), and total leukocyte count. Besides, they ameliorated autoimmunity through suppression of anti-citrullinated protein auto antibodies (anti-CCP) levels in rats. In conclusion our results highlight the benefits which could be obtained of nanoparticles either alone or in combination with the known anti-arthritic and/or anti-inflammatory agents, giving rise to new protocols to maximize the control of RA.

Interstitial Lung Disease and its Associations in Rheumatoid Arthritis: Data from a District General Hospital in Sri Lanka

Context:

Interstitial lung disease (ILD) is a frequent pulmonary manifestation of rheumatoid arthritis (RA). No Sri Lankan studies have determined the prevalence of lung disease in RA and its associations.

Aims:

To find the prevalence of ILD in RA and its association with rheumatoid factor (RF), erosions, Disease activity score in 28 joints (DAS 28), disease duration, Body mass index(BMI), erythrocyte sedimentation rate (ESR), smoking, and also to determine the prevalence of lung disease with demographic factors like age, sex, and income.

Settings and Design:

Questionnaire based retrospective study at a District General Hospital in Sri Lanka.

Materials and Methods:

Diagnosed RA patients included through convenient sampling as it was a simple method that could facilitate data collection in a short duration. Since all patients with a diagnosis of RA were eligible, all consecutive patients with a diagnosis of RA at the rheumatology clinics were included in the study. To reduce the bias a large sample of patients were used as well as patients attending different rheumatology clinics were included and also patients who were referred to the hospital from peripheries were included in the study. The calculated sample size was 384 and according to patient numbers attending clinics, a period of 6 months was decided to select the study sample.

Statistical Analysis Used:

Chi-Square calculation and logistic regression analysis using Minitab 17 software.

Results:

From 384 patients, the prevalence of ILD was 14.58%, been 5.4% in early RA (<2 years disease duration). Mean age of ILD group was 52.94 years (95% CI 64.66-41.22). Mean RA duration was 7.69 years (95% CI, 2.38-12.99). Male to female sex ratio of RA was 1:7, and that of ILD was 2:9. DAS 28 was 4.58 (95% CI, 3.48-5.68). Statistically significant associations were noted with ILD and DAS 28 (P = .0006), ESR (P = .005), RF (P = .03), erosions (P < .00001), and smoking (P < .05). Mean BMI was 22.67 kg and 75.78% had low income (<50 000 rupees/month = 327 US $).

Conclusions:

ILD significantly associates RA severity indices like DAS 28, ESR, erosions, RF, and also with smoking. No significant association was found with BMI or gender difference. Therefore, disease severity indices could be used to predict progression to ILD in RA.

Serum anti-citrullinated protein antibodies and rheumatoid factor increase the risk of rheumatoid arthritis-related interstitial lung disease: a meta-analysis

BACKGROUND

This meta-analysis aims to determine the association between antibodies including anti-citrullinated protein antibodies (ACPA) and rheumatoid factors (RF) and risk of rheumatoid arthritis-related interstitial lung disease (RA-ILD).

METHODS

PubMed, Embase, and Cochrane were searched up to September 13, 2020, for studies investigating the risk of RA-ILD in ACPA-positive patients. The statistical meta-analysis and sensitivity analysis were performed using the Review Manager 5.4 and Stata16.0 software, respectively.

RESULTS

Total 1 double-blind randomized controlled study and 16 observational studies, including 992 RA-ILD patients and 2223 RA-non ILD patients, met the inclusion criteria of the meta-analysis. Compared with ACPA-negative patients, positive serum ACPA increased the risk of RA-ILD (OR = 2.51; 95% CI: 1.35-4.68; P = 0.004) and serum ACPA titer was significantly correlated with risk of RA-ILD (SMD = 0.39; 95% CI: 0.17-0.62; P = 0.0006). In a region-based subgroup analysis, ACPA titer in Asian, European, and African populations was significantly related to the risk of RA-ILD, while there was no significant correlation in the Americans (SMD =  - 0.03; 95% CI: - 0.89-0.83; P = 0.95), especially in the USA (SMD = 0.37; 95% CI: - 0.26-0.99; P = 0.25). In addition, serum positive RF increased the risk of RA-ILD (OR = 2.85; 95% CI: 2.19-3.71; P < 0.00001) and serum RF titer was significantly correlated with the risk of RA-ILD (SMD = 0.35; 95% CI: 0.23-0.46; P < 0.00001). However, for the analysis of RF dichotomous data, the funnel shape was asymmetric and the p value of egger test was less than 0.05, which indicated potential publication bias.

CONCLUSIONS

ACPA and RF positive patients have greater risk of RA-ILD, and RA patients positive for ACPA should be paid more attention.

KEY POINTS

• Autoantibodies ACPA and RF increase the risk of RA-ILD. • Regions may be related to RA-ILD.

Immune disorders and rheumatologic manifestations of viral hepatitis

Infection with hepatotropic viruses is not limited to the liver and can lead to the development of various immunological disorders (the formation of cryoglobulins, rheumatoid factor, antinuclear antibodies, autoantibodies specific for autoimmune hepatitis and primary biliary cholangitis, and others), which can manifest as glomerulonephritis, arthritis, uveitis, vasculitis (cryoglobulinemic vasculitis, polyarteritis nodosa, Henoch-Schonlein purpura, isolated cutaneous necrotizing vasculitis), and other rheumatologic disorders, and be a trigger for the subsequent development of autoimmune hepatitis and primary biliary cholangitis. A further study of the association between autoimmune liver diseases and hepatotropic virus infection would be useful to assess the results of treatment of these associated diseases with antiviral drugs. The relationship of these immune disorders and their manifestations with hepatotropic viruses is best studied for chronic hepatitis B and C. Only isolated cases of these associations are described for hepatitis A. These links are least studied, and are often controversial for hepatitis E, possibly due to their relatively rare diagnoses. Patients with uveitis, glomerulonephritis, arthritis, vasculitis, autoimmune liver diseases should be tested for biomarkers of viral hepatitis, and if present, these patients should be treated with antiviral drugs.

Rheumatoid factor and falsely elevated results in commercial immunoassays: data from an early arthritis cohort

The aim of the study was to  assess RF cross-reactivity to animal antibodies used in immunoassays, and to test if selected commercial immunoassays are vulnerable to interference from RF, causing false test results. Our study included samples from patients with RF-positive rheumatoid arthritis (RA) and controls (patients with RF-negative RA and psoriatic arthritis), included in an early arthritis-cohort. Reactivity to mouse IgG1, mouse IgG2a, rabbit IgG, bovine IgG, sheep/goat IgG and human IgG was analysed using in-house interference assays. RF-positive sera with strong reactivity to mouse IgG1 were analysed in three commercial immunoassays. To reveal interference, results before and after addition of blocking aggregated murine IgG1 were compared. Samples from 124 RF-positive RA patients and 66 controls were tested. We found considerably stronger reactivity toward animal antibodies, particularly mouse IgG1 (73% vs. 12%) and rabbit IgG (81% vs. 6%), in sera from RF-positive RA-patients compared to controls (p < 0.001). After selecting samples for testing in commercial assays, interference was revealed in 6/30 sera in the Architect β-hCG assay, 7/10 sera in the 27-plex cytokine assays, and in 2/33 samples in the Elecsys Soluble Transferrin Receptor assay. Our study revealed considerable RF reactivity to animal antibodies used in immunoassays and RF was associated with falsely elevated results in immunoassays used in clinical care and research. Clinicians, laboratorians, researchers and assay manufacturers must be alert to the risk of falsely elevated test results in RF-positive RA patients.

Performance of a commercially available multiplex platform in the assessment of circulating cytokines and chemokines in patients with rheumatoid arthritis and osteoarthritis

BACKGROUND/OBJECTIVE

Cytokines and chemokines (cytokines) are central to rheumatoid arthritis (RA) pathogenesis, with increasing use of multiplex immunoassays in clinical/research settings. Rheumatoid factor (RF) may interfere with assay outcomes by nonspecifically binding detection analytes. We evaluated the performance of a commercially available multiplex platform, including assessment of the impact of RF depletion.

METHODS

Forty-five cytokines were tested using Meso Scale Discovery V-PLEX™ and samples from 40 RA and 40 osteoarthritis (OA) patients. Select samples were depleted of RF using a commercial binder. Performance was assessed using intra-assay coefficients of variation (CV), intraclass correlation coefficients (ICC), percent change following RF depletion, and disease discrimination. Values above or below quantification thresholds were imputed.

RESULTS

Of the 45 cytokines analyzed, 31 yielded CVs <10%; none demonstrated CVs >30%. ICCs universally exceeded 0.85 with the exception of eight analytes. RF depletion altered cytokine values by <15% for 40 analytes with larger changes (>30%) only seen for one analyte. Twenty-three cytokines differed significantly based on measurement in plasma vs. serum. Three analytes were higher in the serum of RA vs. OA (IL-10, IP-10, TNFα), and none were significantly greater in OA vs. RA. Seventeen analytes required imputation for >50% of the samples tested, primarily related to concentrations below the lower limit of quantification threshold.

CONCLUSION

The results from this commercially available multiplex assay were generally highly reproducible and interference induced by RF only meaningfully impacted the quantification of five of the analytes examined.

Impending radiographic erosive progression over the following year in a cohort of consecutive patients with inflammatory polyarthritis: prediction by serum biomarkers

BACKGROUND/PURPOSE

To evaluate biomarkers as predictors of impending erosion progression.

METHODS

Variables were measured at baseline and annually up to 5 years in patients with recent-onset polyarthritis treated to zero swollen joints. Erosive status was defined as ≥5 Units in Sharp/van der Heijde Erosion Score; Rapid Erosive Progression (REP) was defined as an increase ≥5 Units in Erosion Scores between consecutive visits. Generalised estimating equations (GEEs) evaluated the effect on REP of positive anticyclic citrullinated peptides (ACPAs) and/or rheumatoid factor (RF), C-reactive protein ˃8.0 mg/L (High-CRP) and 14-3-3η protein ≥0.50 ng/mL (High-14-3-3η), alone and in combinations.

RESULTS

Out of 2155 evaluations in 749 consecutive patients, REP occurred after 186 (8.6%) visits, including 13 (2.2%) in patients recruited since 2010. Only 18/537 (3.4%; 6/411 (1.5%) in non-erosive vs 12/126 (9.5%) in patients already erosive) visits without any positive biomarker were followed by REP; at least one biomarker was positive prior to REP in 168/186 (90.3%) visits. Being positive for all four biomarkers conferred a positive predictive value (PPV) of 30.0% (RR 21.8) in patients non-erosive at the visit versus 35.5% (RR 3.07) in those already erosive. High-14-3-3η increased REP only in visits with High-CRP (eg, RR 2.5 to 3.9 when ACPA also positive) and in patients with non-erosive status (eg, RR from 4.3 to 9.4 when also High-CRP).

CONCLUSIONS

Adding High-14-3-3η to positive antibodies and CRP improves prediction of impending REP. Although REP is becoming rarer, signatures of biomarkers might help to adapt treatment strategies in at-risk individuals, even those already erosive.

Rheumatoid Arthritis: Early Diagnosis and Treatment

Rheumatoid arthritis (RA) is a chronic, progressive inflammatory disorder that manifests as a symmetric polyarthritis of small and large joints that may lead to joint and periarticular structural damage and the consequences of systemic inflammation. This overview of early RA examines the unmet needs and challenges in RA, how to best diagnose RA, and pitfalls in early diagnosis and treatment. The rules for referral to a rheumatologist are reviewed. Primary care physicians are at the front line of early diagnosis and need to start disease-modifying therapy as soon as a diagnosis of RA is established.

Prevalence and significance of serum 14-3-3η in juvenile idiopathic arthritis

BACKGROUND

Prompt diagnosis of juvenile idiopathic arthritis (JIA) is important to avoid long term complications. Elevated serum 14-3-3η levels improve the diagnostic sensitivity of rheumatoid factor (RF) and cyclic citrullinated peptide (CCP) antibody in adult rheumatoid arthritis (RA), and have been associated with more severe phenotype. We investigated the prevalence and clinical significance of serum 14-3-3η in different types of JIA.

METHODS

JIA patients (n = 151) followed by the Pediatric Rheumatology Core at Children's Hospital of Los Angeles were categorized into 5 groups: polyarticular JIA RF+ (PJIA RF+; n = 39), PJIA RF- (n = 39), psoriatic arthritis (PsA; n = 19), enthesitis-related arthritis (ERA; n = 18), and oligoarticular JIA (OJIA [control group]; n = 36). RF, CCP antibody, and 14-3-3η were measured for all patients. 14-3-3η serum levels > 0.2 ng/mL were considered positive. Disease activity was assessed by the Juvenile Arthritis Disease Activity Score-71 (JADAS-71).

RESULTS

Elevated 14-3-3η levels were detected in 34/151 (23%) patients, and across all groups tested. Most patients with 14-3-3η had titers ≥4 times above the cutoff value. The majority (22, 65%) of 14-3-3η-positive patients were also positive for RF or CCP antibodies, 16 (47%) were positive for all 3, and 12 (35%) were single-positive for 14-3-3η. The highest prevalence of 14-3-3η was in PJIA RF+ patients (49%), followed by OJIA (22%). Positivity for 14-3-3η was not significantly associated with disease activity or age at diagnosis.

CONCLUSION

Serum 14-3-3η can be detected in all forms of JIA tested but appears to be most common in PJIA RF+. 14-3-3η does not appear to correlate with disease activity in JIA.

IgA immunoglobulin isotype of rheumatoid factor in primary Sjögren's syndrome

Primary Sjögren’s syndrome (pSS) is an autoimmune disease with autoantibodies overproduction, including rheumatoid factors (RF). RF-IgA, IgG immunoglobulin classes are suggested as potential biomarkers of pSS. We studied 76 patients with pSS (ACR/Eular 2017); laboratory tests included ESR, C-reactive protein, concentrations of gamma globulins, RF, Anti-SS-A/Ro, and anti-SS-B/La. Eye dryness and keratoconjunctivitis sicca were confirmed with Schirmer’s test, the ocular staining score (OSS) using lissamine green, fluorescein staining and biopsy of minor salivary gland with the histopathological evaluation. Differences between groups were analyzed with U Mann–Whitney test. Correlations between quantitative variables were assessed with the Spearman correlation coefficient.. The best diagnostic values of immunoglobulin concentration for discriminating pSS patients and healthy individuals are for RF-IgA. With cut-off of 21.5 EU/mL, the sensitivity is 72% and specificity is 100%. Very high specificity (100%) is also obtained for RF-IgM concentration of 74.1 EU/mL. Sensitivity is, however, smaller than that for RF-IgA and amounted to 61%. The RF-IgG is the poorest indicator of pSS with 51% of sensitivity and 95% of specificity. To summarize RF-IgA strongly associate with anti-SS-A and anti-SS-B autoantibodies. Both RF-IgA and RF-IgM may be used as diagnostic tools for pSS. Conclusions: among the three studied rheumatoid factor subtypes, RF-IgA showed the best diagnostic accuracy for pSS. RF-IgA correlated with anti-SS-A/Ro and anti-SS-B antibodies even more closely than RF-IgM. The assessment of the RF-IgA serum concentration may be helpful in the process of establishing pSS diagnosis.

The significance of serum 14-3-3η level in rheumatoid arthritis patients

BACKGROUND

RA is a systemic inflammatory condition characterized by chronic arthritis and often associated with irreversible joint damage.

OBJECTIVES

To assess the significance of serum level of 14-3-3η in RA and its association with clinical and serological features of the disease.

METHODS

This is a case-control study done on 80 participants. They were divided into 2 groups. Group 1: 40 rheumatoid arthritis patients compared to group 2: 40 healthy participants matched for age and sex. Laboratory investigations including complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) rheumatoid factor (RF), anti-citrullinated peptide antibodies (ACPAs), and serum 14-3-3η were done to all participants. Radiological examination in the form of plain X-ray for hands and feet was done to all patients.

RESULTS

Serum levels of 14-3-3η were significantly higher in RA patients compared to the control group (p < 0.001). Serum 14-3-3η was the only predictor of high Larsen's score (p = 0.013) on using linear regression analysis. Serum 14-3-3η can predict RA in healthy controls in univariate (p = 0.001) and multivariate (p = 0.004) analyses. The receiver operating characteristic (ROC) curve of 14-3-3η was constructed for discrimination between RA and control subjects. The best cut-off value was 61.9 ng/mL, with fair AUC (0.773, p < 0.001), 95% CI (0.656-0.889), and the sensitivity and specificity of 14-3-3η for RA diagnosis as 65% and 95% respectively. Also, we constructed ROC curves for RF, ACPA, 14-3-3η, and their combinations; we found that the highest test sensitivity of 95.7% appeared on adding the 3 markers together, and the highest test specificity of 100% was detected on adding RF to ACPA, 14-3-3η to ACPA or the 3 molecules together.

CONCLUSION

14-3-3η could be a valuable marker for the diagnosis of RA patients and it may have prognostic value. Key Points • 14-3-3η is a valuable marker for the diagnosis of RA patients. • 14-3-3η reflects disease severity and joint damage in RA patients.

The Clinical Utility of Autoantibodies in Patients with Idiopathic Granulomatous Mastitis

BACKGROUND

Although the etiopathogenesis of idiopathic granulomatous mastitis (IGM) is still controversial, recently autoimmunity and immune dysregulation have been emphasized. The aim of this study is to investigate the clinical utility of autoantibodies in IGM.

MATERIAL AND METHODS

Rheumatoid factor (RF), antinuclear antibody (ANA), anti-double stranded DNA antibody (anti-ds-DNA), anti-cyclic citrullinated peptides antibody (anti-CCP) and perinuclear anti-neutrophil cytoplasmic antibody (pANCA) levels were investigated in pathologically diagnosed IGM patients (Group IGM) and healthy women (Group C). IGM patients were divided into two groups as those with active symptoms and signs (Group IGM_A) and those without clinical and radiological findings (Group IGM_R).

RESULTS

While, in Group IGM, the positivity of RF, ANA, anti-ds-DNA, pANCA and anti-CCP was 13.1%, 3.3%, 1.6%, 0%, and 3.3%, respectively, in Group C, they were 13.3%, 0%, 0%, 0%, and 0%, respectively. The differences were not statistically significant (p > .05). In Groups IGM_A, IGM_R and C, RF positivity was 10%, 16.1%, and 13.3%, respectively. The ANA positivity of Groups IGM_A, IGM_R and C was 0%, 6.5%, and 0%, respectively. Groups IGM_A, IGM_R and C's anti-ds-DNA positivity were 0%, 3.2%, and 0%, respectively. In all groups, pANCA was negative. The anti-CCP positivity of Groups IGM_A, IGM_R and C was 6.7%, 0%, and 0%, respectively.

CONCLUSION

Our findings did not support the clinical utility of autoantibodies including RF, ANA, anti-ds-DNA, pANCA and anti-CCP in IGM.

IgG subclasses in cryoglobulins: link to composition and clinical manifestations

BACKGROUND

Cryoglobulins (CG) are immunoglobulins which precipitate at low temperature. The analysis of IgG subclass composition of CG is poorly reported. The aim of this study was to determine the subclasses of IgG-containing type I and mixed type II and III CG in relation to clinical manifestations.

METHODS

Out of a previous series of 1675 patients, inclusion criteria were a cryoprecipitate > 1 mL and a total IgG > 300 mg/L. IgG subclasses were quantified by immunoturbidimetry, rheumatoid factor (RF), and C4 by immunonephelometry. Clinical parameters were collected from hospital charts.

RESULTS

CG samples from 86 patients were included, 10 type I CG and 76 mixed CG. Type I CG subclasses were IgG1 (6/10) and IgG2/IgG3 (4/10), never IgG4. IgG subclass in type II vs. III CG were 73.3 ± 15.2% vs. 52.5 ± 20.7% for IgG1 (p < 0.0001), 15.4 ± 8.2% vs. 25.9 ± 14% for IgG2 (p < 0.0001), 8.4 ± 12.4 vs. 21.2 ± 14% for IgG3 (p < 0.0001), and 3 ± 5.2% vs. 0.5 ± 1.2 for IgG4 (p < 0.0001). In mixed CG, the higher proportion of IgG4 was associated with RF positive CG (p = 0.01) and low C4 (p = 0.01). In type I CG, IgG1 were associated with severe vasculitis manifestations, IgG2/IgG3 with cutaneous or renal manifestations. In mixed CG, IgG2 was the only subclass associated with CG manifestations, with a higher concentration in asymptomatic (162.6 ± 29.5 mg/L) vs. symptomatic patients with cutaneous (103 ± 17.8 mg/L, p = 0.04) and neurological (108 ± 24 mg/L, p = 0.04) manifestations.

CONCLUSION

In type I IgG CG, IgG1 was the main CG subclass associated with CG vasculitis. In mixed CG, low IgG2 concentration was linked to CG cutaneous and neurological manifestations.