Systematic review: accuracy of anti-citrullinated Peptide antibodies for diagnosing rheumatoid arthritis

Distinct mucosal endotypes as initiators and drivers of rheumatoid arthritis

Rheumatoid arthritis (RA) is a potentially devastating autoimmune disease. The great majority of patients with RA are seropositive for anti-citrullinated protein antibodies (ACPAs), rheumatoid factors, or other autoantibodies. The onset of clinically apparent inflammatory arthritis meeting classification criteria (clinical RA) is preceded by ACPA seropositivity for an average of 3-5 years, a period that is designated as 'at-risk' of RA for ACPA-positive individuals who do not display signs of arthritis, or 'pre-RA' for individuals who are known to have progressed to developing clinical RA. Prior studies of individuals at-risk of RA have associated pulmonary mucosal inflammation with local production of ACPAs and rheumatoid factors, leading to development of the 'mucosal origins hypothesis'. Recent work now suggests the presence of multiple distinct mucosal site-specific mechanisms that drive RA evolution. Indicatively, subsets of individuals at-risk of RA and patients with RA harbour a faecal bacterial strain that has exhibited arthritogenic activity in animal models and that favours T helper 17 (TH17) cell responses in patients. Periodontal inflammation and oral microbiota have also been suggested to promote the development of arthritis through breaches in the mucosal barrier. Herein, we argue that mucosal sites and their associated microbial strains can contribute to RA evolution via distinct pathogenic mechanisms, which can be considered causal mucosal endotypes. Future therapies instituted for prevention in the at-risk period, or, perhaps, during clinical RA as therapeutics for active arthritis, will possibly have to address these individual mechanisms as part of precision medicine approaches.

A comparison of anti-cyclic citrullinated peptides (CCP3 and CCP3.1) autoantibody tests in rheumatoid arthritis

Background

Anti-citrullinated protein antibodies (ACPA) are a specific serological biomarker used in the diagnosis of rheumatoid arthritis (RA). In clinical practice ACPA can be identified using immunoassays targeting synthetic cyclic citrullinated peptides (CCP). The 3rd generation anti-CCP IgG antibody (CCP3) offers improved sensitivity compared to the earlier versions. Recently, CCP3.1, capable of detecting both IgG and IgA antibodies, was introduced to enhance sensitivity, especially in patients with early RA.

Methods

We assessed serum CCP3.1 against CCP3 in 331 subjects undergoing RA panel serology, comprising 136 patients with RA and 195 patients without RA. Sera were tested for anti-CCP IgG (CCP3) and anti-CCP IgG/IgA (CCP3.1) antibodies. Clinical performance of these tests was compared at manufacturer-suggested cutoffs. A separate set of 81 patients with a diagnosis of RA by 2010 criteria and whose samples were obtained from within 1-year of RA diagnosis was similarly assessed to evaluate assay performance in an independent clinical RA cohort.

Results

Overall diagnostic accuracy was similar; CCP3 had an area under the curve (AUC) of 0.88, CCP3.1 had an AUC of 0.89. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for CCP3 were 79 %, 91 %, 86 %, and 86 %, respectively. For CCP3.1, sensitivity was 78 %, specificity 93 %, PPV 89 %, NPV 86 %. Both assays demonstrated excellent agreement; positive percent agreement of 94 % and negative percent agreement of 99 %.

Conclusion

Our findings indicate comparable diagnostic accuracy between CCP3 and CCP3.1 assays in these clinical cohorts.

Profile of Nagasaki Islands Study (NaIS): A Population-based Prospective Cohort Study on Multi-disease

In an aging society, it is important to visualize the conditions of people living with diseases or disabilities, such as frailty and sarcopenia, and determine the environmental and genetic factors underlying such conditions. Atherosclerosis and arterial stiffness are key conditions between these factors and noncommunicable diseases. In 2014, we launched a population-based prospective open-cohort study, the Nagasaki Islands Study (NaIS), which was conducted in Goto City, located in the remote islands of Nagasaki Prefecture, Japan, mostly involving middle-aged and older residents. We conducted our own health checkups along with the annual standardized checkups organized by the municipality; recruited study participants; and started to follow them for vital status (death), migration, and occurrence of diseases, such as myocardial infarction, stroke, fracture, and human T-cell leukemia virus type 1 (HTLV-1)-associated uveitis. Our checkups were conducted as baseline surveys in different areas of Goto City during the fiscal years 2014-2016, secondary surveys during 2017-2019, and tertiary surveys since 2021, consisting of medical interviews, physical examinations, blood and urine tests, body composition measurements, osteoporosis screening, arterial stiffness measurements, carotid ultrasonography, and dental examination. A total of 4,957 residents participated in either the baseline or secondary surveys and were followed; 3,594 and 3,364 residents (aged 27-96 and 28-98 years) participated in the baseline and secondary surveys, respectively. In conclusion, the NaIS has been undertaken to reveal the influence of aging and risk factors of noncommunicable diseases and disabilities, with an aim to contribute towards better healthcare in the future.

Serum and urine lipidomic profiles identify biomarkers diagnostic for seropositive and seronegative rheumatoid arthritis

Objective

Seronegative rheumatoid arthritis (RA) is defined as RA without circulating autoantibodies such as rheumatoid factor and anti-citrullinated protein antibodies; thus, early diagnosis of seronegative RA can be challenging. Here, we aimed to identify diagnostic biomarkers for seronegative RA by performing lipidomic analyses of sera and urine samples from patients with RA.

Methods

We performed untargeted lipidomic analysis of sera and urine samples from 111 RA patients, 45 osteoarthritis (OA) patients, and 25 healthy controls (HC). These samples were divided into a discovery cohort (n = 97) and a validation cohort (n = 84). Serum samples from 20 patients with systemic lupus erythematosus (SLE) were also used for validation.

Results

The serum lipidome profile of RA was distinguishable from that of OA and HC. We identified a panel of ten serum lipids and three urine lipids in the discovery cohort that showed the most significant differences. These were deemed potential lipid biomarker candidates for RA. The serum lipid panel was tested using a validation cohort; the results revealed an accuracy of 79%, a sensitivity of 71%, and a specificity of 86%. Both seropositive and seronegative RA patients were differentiated from patients with OA, SLE, and HC. Three urinary lipids showing differential expression between RA from HC were identified with an accuracy of 84%, but they failed to differentiate RA from OA. There were five lipid pathways that differed between seronegative and seropositive RA.

Conclusion

Here, we identified a panel of ten serum lipids as potential biomarkers that can differentiate RA from OA and SLE, regardless of seropositivity. In addition, three urinary lipids had diagnostic utility for differentiating RA from HC.

Shift in perspective: autoimmunity protecting against rheumatoid arthritis

A hallmark of rheumatoid arthritis (RA) is the increased levels of autoantibodies preceding the onset and contributing to the classification of the disease. These autoantibodies, mainly anti-citrullinated protein antibody (ACPA) and rheumatoid factor, have been assumed to be pathogenic and many attempts have been made to link them to the development of bone erosion, pain and arthritis. We and others have recently discovered that most cloned ACPA protect against experimental arthritis in the mouse. In addition, we have identified suppressor B cells in healthy individuals, selected in response to collagen type II, and these cells decrease in numbers in RA. These findings provide a new angle on how to explain the development of RA and maybe also other complex autoimmune diseases preceded by an increased autoimmune response.

Clinical implications of seropositive and seronegative autoantibody status in rheumatoid arthritis patients: A comparative multicentre observational study

Background and Objectives

Rheumatoid factor (RF) and anti-cyclic citrullinated protein (anti-CCP) have been used to improve the diagnosis and prognosis of rheumatoid arthritis (RA). However, their association with RA disease phenotypes, individually and in combination, is not well studied. The aim of the study was to compare patients' and disease characteristics, activity and severity in double seronegative (DNRA), single seropositive RF, single seropositive anti-CCP and double seropositive (DPRA) patients.

Methods

Adults subjects with RA from Egyptian College of Rheumatology (ECR) database who had RF and anti-CCP results available were included. Demographic, clinical features, disease activity score 28 (DAS28), Health Assessment Questionnaire (HAQ) and laboratory data were collected and compared among different RA groups.

Results

5268 RA patients with mean age of 44.9±11.6 years, and 4477 (85%) were females. 2900 (55%) had DPRA, 892 (16.9%) had single positive RF, 597 (11.3%) had single positive anti-CCP while 879 (16.7%) had DNRA. Patients with DPRA had significantly high percentage of metabolic syndrome (19.3%, P < 0.001), and functional impairment using HAQ (P = 0.01). Older age (RRR [relative risk ratio]: 1.03, 95%CI: 1.0, 1.0, P = 0.029), greater DAS28 (RRR: 1.51, 95%CI: 1.2, 1.9, P < 0.001), higher steroid use (RRR: 2.4, 95%CI: 1.36, 4.25, P = 0.002) were at higher risk of DPRA while longer disease duration (RRR: 1.08, 95%CI: 1.01, 1.16, P = 0.017) and fibromyalgia syndrome (RRR: 2.54, 95%CI: 1.10, 5.88, P = 0.028) were associated with higher odds of single positive RF status.

Conclusion

Dual antibody-positive status has higher disease activity and severity, and higher chance of development of metabolic syndrome; highlighting the implicated role of inflammation, atherogenesis and cardiovascular disease risk in RA.

Software with artificial intelligence-derived algorithms for analysing CT brain scans in people with a suspected acute stroke: a systematic review and cost-effectiveness analysis

Background

Artificial intelligence-derived software technologies have been developed that are intended to facilitate the review of computed tomography brain scans in patients with suspected stroke.

Objectives

To evaluate the clinical and cost-effectiveness of using artificial intelligence-derived software to support review of computed tomography brain scans in acute stroke in the National Health Service setting.

Methods

Twenty-five databases were searched to July 2021. The review process included measures to minimise error and bias. Results were summarised by research question, artificial intelligence-derived software technology and study type. The health economic analysis focused on the addition of artificial intelligence-derived software-assisted review of computed tomography angiography brain scans for guiding mechanical thrombectomy treatment decisions for people with an ischaemic stroke. The de novo model (developed in R Shiny, R Foundation for Statistical Computing, Vienna, Austria) consisted of a decision tree (short-term) and a state transition model (long-term) to calculate the mean expected costs and quality-adjusted life-years for people with ischaemic stroke and suspected large-vessel occlusion comparing artificial intelligence-derived software-assisted review to usual care.

Results

A total of 22 studies (30 publications) were included in the review; 18/22 studies concerned artificial intelligence-derived software for the interpretation of computed tomography angiography to detect large-vessel occlusion. No study evaluated an artificial intelligence-derived software technology used as specified in the inclusion criteria for this assessment. For artificial intelligence-derived software technology alone, sensitivity and specificity estimates for proximal anterior circulation large-vessel occlusion were 95.4% (95% confidence interval 92.7% to 97.1%) and 79.4% (95% confidence interval 75.8% to 82.6%) for Rapid (iSchemaView, Menlo Park, CA, USA) computed tomography angiography, 91.2% (95% confidence interval 77.0% to 97.0%) and 85.0 (95% confidence interval 64.0% to 94.8%) for Viz LVO (Viz.ai, Inc., San Fransisco, VA, USA) large-vessel occlusion, 83.8% (95% confidence interval 77.3% to 88.7%) and 95.7% (95% confidence interval 91.0% to 98.0%) for Brainomix (Brainomix Ltd, Oxford, UK) e-computed tomography angiography and 98.1% (95% confidence interval 94.5% to 99.3%) and 98.2% (95% confidence interval 95.5% to 99.3%) for Avicenna CINA (Avicenna AI, La Ciotat, France) large-vessel occlusion, based on one study each. These studies were not considered appropriate to inform cost-effectiveness modelling but formed the basis by which the accuracy of artificial intelligence plus human reader could be elicited by expert opinion. Probabilistic analyses based on the expert elicitation to inform the sensitivity of the diagnostic pathway indicated that the addition of artificial intelligence to detect large-vessel occlusion is potentially more effective (quality-adjusted life-year gain of 0.003), more costly (increased costs of £8.61) and cost-effective for willingness-to-pay thresholds of £3380 per quality-adjusted life-year and higher.

Limitations and conclusions

The available evidence is not suitable to determine the clinical effectiveness of using artificial intelligence-derived software to support the review of computed tomography brain scans in acute stroke. The economic analyses did not provide evidence to prefer the artificial intelligence-derived software strategy over current clinical practice. However, results indicated that if the addition of artificial intelligence-derived software-assisted review for guiding mechanical thrombectomy treatment decisions increased the sensitivity of the diagnostic pathway (i.e. reduced the proportion of undetected large-vessel occlusions), this may be considered cost-effective.

Future work

Large, preferably multicentre, studies are needed (for all artificial intelligence-derived software technologies) that evaluate these technologies as they would be implemented in clinical practice.

Study registration

This study is registered as PROSPERO CRD42021269609.

Funding

This award was funded by the National Institute for Health and Care Research (NIHR) Evidence Synthesis programme (NIHR award ref: NIHR133836) and is published in full in Health Technology Assessment; Vol. 28, No. 11. See the NIHR Funding and Awards website for further award information.

Recent Advances in Biosensors for Diagnosis of Autoimmune Diseases

Over the last decade, autoimmune diseases (ADs) have undergone a significant increase because of genetic and/or environmental factors; therefore, their simple and fast diagnosis is of high importance. The conventional diagnostic techniques for ADs require tedious sample preparation, sophisticated instruments, a dedicated laboratory, and qualified personnel. For these reasons, biosensors could represent a useful alternative to these methods. Biosensors are considered to be promising tools that can be used in clinical analysis for an early diagnosis due to their high sensitivity, simplicity, low cost, possible miniaturization (POCT), and potential ability for real-time analysis. In this review, recently developed biosensors for the detection of autoimmune disease biomarkers are discussed. In the first part, we focus on the main AD biomarkers and the current methods of their detection. Then, we discuss the principles and different types of biosensors. Finally, we overview the characteristics of biosensors based on different bioreceptors reported in the literature.

Clinical, Immunological and Inflammatory Characteristics among Mexican Children with Different Subtypes of Juvenile Idiopathic Arthritis: Exploring the Correlation between Anti-Cyclic Citrullinated Peptide (anti-CCP) and Rheumatoid Factor (RF)

INTRODUCTION

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease in childhood, affecting one to four of every 1000 children worldwide. It is characterized by joint inflammation lasting more than six weeks in children under 16 years. The aim of this study was to estimate the frequency of JIA subtypes in the Mexican patient population; compare clinical, immunological and inflammation markers by JIA subtype; and examine the correlation between these variables.

METHODS

We conducted a cross-sectional study of 50 patients with JIA (2-15 years). We estimated the frequency of each JIA subtype, assessed and compared the immunological characteristics (RF, ANA and anti-CCP) by JIA subtype at the time of diagnosis using Kruskal-Wallis or chi-square tests, and calculated Spearman correlation coefficients between the assessments.

RESULTS

Our analysis included 50 patients, 29 (58%) girls and 21 (42%) boys, aged at the time of diagnosis 10.56  ±  3.99 years. The frequencies of JIA subtypes were RF-seropositive polyarthritis (34%), RF-seronegative polyarthritis (28%), systemic arthritis (16%), oligoarthritis (14%) and arthritis-related enthesitis (8%). We found a significant association between sex and JIA subtype (p = 0.014). There was a significant difference in anti-CCP levels by JIA subtype (p < 0.001). We also detected positive correlations between RF and anti-CCP (r = 0.63, p < 0.001) and between age and anti-CCP (r = 0.29, p = 0.041).

CONCLUSIONS

Our study suggests that the frequency of the polyarticular subtypes of JIA is higher in Mexican children compared to other populations. Our findings highlight the importance of considering the presence of anti-CCP and RF as important criteria when deciding on treatment for JIA patients as elevated levels of these antibodies may indicate early forms of adult rheumatoid arthritis.

Double positivity for rheumatoid factor and anti-CCP autoantibodies: improving referral from primary care of patients suspected of having rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic progressive autoimmune inflammatory disease with significant morbidity and mortality. The course of the disease can be modified if diagnosis is early and treatment appropriate.

AIM

In this study, we aimed to evaluate a new strategy for early identification of RA patients in primary care settings (the 'diagnostic bottleneck') based on serological biomarkers and to manage inappropriate rheumatoid factor (RF) laboratory test requests.

METHOD

A two-arm study was carried out. The first arm corresponded to a retrospective observational descriptive study of patients referred for RF testing from primary care using the current laboratory workflow. The second arm included the following prospective interventions: cancelation of RF requests corresponding to patients with previous negative results for RF over a one-year period; and automatic reflex testing antibodies against cyclic citrullinated proteins (anti-CCP) for patients displaying RF values >30 IU/ml. Outcomes from both arms were then compared.

FINDINGS

As double positivity for RF and anti-CCP notably increases the positive likelihood ratio of RA. The intervention enabled a reduction of 2813 tests in 22 months. Moreover, the frequency of unnecessary referrals was reduced from 22% to 8.2%, while that of missed patients decreased slightly (from 21% to 16%), with the number of patients diagnosed per RF request remaining unchanged. In terms of costs, we saved 19.4 RF tests per anti-CCP test added.We developed a simple and cost-effective strategy for reducing the time to diagnosis of RA that can improve patients' quality of life. This approach was supported by primary and specialised care.

Rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory multisystemic disease of unknown etiology and autoimmune nature that predominantly affects peripheral joints in a symmetrical fashion. Although much progress has been made in understanding the pathophysiology of RA, its etiology remains unknown. Tumor necrosis factor (TNF)-α and interleukin (IL)-6 play the important roles in the pathogenesis and maintenance of inflammation in RA. The presence of anti-citrullinated peptide antibodies aids in the diagnosis in patients with undifferentiated polyarthritis and is associated with a more aggressive RA. The natural history of RA causes joint deformity and disability, as well as reduced life expectancy, both due to increased cardiovascular risk, pulmonary involvement, infections, iatrogenesis or tumors. Early diagnosis and the use of targeted drugs to induce early remission have improved the RA prognosis.

Limited clinical validity of univariate resting-state EEG markers for classifying seizure disorders

Differentiating between epilepsy and psychogenic non-epileptic seizures presents a considerable challenge in clinical practice, resulting in frequent misdiagnosis, unnecessary treatment and long diagnostic delays. Quantitative markers extracted from resting-state EEG may reveal subtle neurophysiological differences that are diagnostically relevant. Two observational, retrospective diagnostic accuracy studies were performed to test the clinical validity of univariate resting-state EEG markers for the differential diagnosis of epilepsy and psychogenic non-epileptic seizures. Clinical EEG data were collected for 179 quasi-consecutive patients (age > 18) with a suspected diagnosis of epilepsy or psychogenic non-epileptic seizures who were medication-naïve at the time of EEG; 148 age- and gender-matched patients subsequently received a diagnosis from specialist clinicians and were included in the analyses. Study 1 is a hypothesis-driven study testing the ability of theta power and peak alpha frequency to classify people with epilepsy and people with psychogenic non-epileptic seizures, with an advanced machine learning pipeline. The next study (Study 2) is data-driven; a high number of quantitative EEG features are extracted and a similar machine learning approach as Study 1 assesses whether previously unexplored univariate EEG measures show promise as diagnostic markers. The results of Study 1 suggest that EEG markers that were previously identified as promising diagnostic indicators (i.e. theta power and peak alpha frequency) have limited clinical validity for the classification of epilepsy and psychogenic non-epileptic seizures (mean accuracy: 48%). The results of Study 2 indicate that identifying univariate markers that show good correlation with a categorical diagnostic label is challenging (mean accuracy: 45-60%). This is due to a considerable overlap in neurophysiological features between the diagnostic classes considered in this study, and to the presence of more dominant EEG dynamics such as alterations due to temporal proximity to epileptiform discharges. Markers that were identified in the context of previous epilepsy research using visually normal resting-state EEG were found to have limited clinical validity for the classification task of distinguishing between people with epilepsy and people with psychogenic non-epileptic seizures. A search for alternative diagnostic markers uncovered the challenges involved and generated recommendations for further research.

Multifaceted immune dysregulation characterizes individuals at-risk for rheumatoid arthritis

Molecular markers of autoimmunity, such as antibodies to citrullinated protein antigens (ACPA), are detectable prior to inflammatory arthritis (IA) in rheumatoid arthritis (RA) and may define a state that is 'at-risk' for future RA. Here we present a cross-sectional comparative analysis among three groups that include ACPA positive individuals without IA (At-Risk), ACPA negative individuals and individuals with early, ACPA positive clinical RA (Early RA). Differential methylation analysis among the groups identifies non-specific dysregulation in peripheral B, memory and naïve T cells in At-Risk participants, with more specific immunological pathway abnormalities in Early RA. Tetramer studies show increased abundance of T cells recognizing citrullinated (cit) epitopes in At-Risk participants, including expansion of T cells reactive to citrullinated cartilage intermediate layer protein I (cit-CILP); these T cells have Th1, Th17, and T stem cell memory-like phenotypes. Antibody-antigen array analyses show that antibodies targeting cit-clusterin, cit-fibrinogen and cit-histone H4 are elevated in At-Risk and Early RA participants, with the highest levels of antibodies detected in those with Early RA. These findings indicate that an ACPA positive at-risk state is associated with multifaceted immune dysregulation that may represent a potential opportunity for targeted intervention.

Approach to laboratory ordering and interpretation in rheumatology

Evaluation of suspected rheumatic disease is a significant challenge due to overlapping and sometimes non-specific clinical features. Most laboratory tests in rheumatic disease have incomplete sensitivity and specificity, leading to positive results without disease and negative results despite disease presence. Therefore, judicious ordering and correct interpretation of laboratory testing in rheumatology is critical in order to provide high-value care. Herein we review laboratory testing in rheumatology in the context of a framework for approaching rheumatic disease.

Matrix metalloproteinases in arthritis: towards precision medicine

Proteolysis of structural molecules of the extracellular matrix (ECM) is an irreversible post-translational modification in all arthropathies. Common joint disorders, including osteoarthritis and rheumatoid arthritis, have been associated with increased levels of matrix remodelling enzymes, including matrix metalloproteinases (MMPs). MMPs, in concert with other host proteinases and glycanases, destroy proteoglycans, collagens and other ECM molecules. MMPs may also control joint remodelling indirectly by signalling through cell-surface receptors or by proteolysis of cytokines and receptor molecules. After synthesis as pro-forms, MMPs can be activated by various types of post-translational modifications, including proteolysis. Once activated, MMPs are controlled by general and specific tissue inhibitors of metalloproteinases (TIMPs). In rheumatoid arthritis, proteolysis of the ECM results in so-called remnant epitopes that enhance and perpetuate autoimmune processes in susceptible hosts. In osteoarthritis, the considerable production of MMP-13 by chondrocytes, often concurrent with mechanical overload, is a key event. Hence, information about the regulation, timing, localization and activities of MMPs in specific disease phases and arthritic entities will help to develop better diagnostics. Insights into beneficial and detrimental effects of MMPs on joint tissue inflammation are also necessary to plan and execute (pre)clinical studies for better therapy and precision medicine with MMP inhibitors. With the advances in proteomics and single-cell transcriptomics, two critical points need attention: neglected neutrophil MMP biology, and the analysis of net proteolytic activities as the result of balances between MMPs and their inhibitors.

The assessment of rheumatoid factor levels and hemogram parameters as predictors for rheumatologic disease

AIM

Many markers are used for clinical diagnosis in rheumatic diseases; rheumatoid factor (RF) is the most frequently used marker. However, RF is not specific to rheumatoid arthritis (RA). RF positivity is widely observed in patients with advanced age, infectious, autoimmune, and lymphoproliferative diseases. In this context, the objective of this study is to investigate the demographic characteristics, frequency of antinuclear antibody (ANA) and anti-cyclic citrullinated peptide (anti-CCP) positivity, hemogram parameters and distribution of the diagnoses in RF-positive patients followed at the rheumatology clinic.

METHODS

The population of this retrospective study consisted of patients above 18 years of age who were referred to have RF positivity by nephelometric method at Kahramanmaraş Necip Fazıl City Hospital Rheumatology Clinic between January 2020 and June 2022.

RESULTS

The mean age of the 230 patients with a positive RF test result, 155 (76%) male and 55 (24%) female, was 52.7 ± 15.5 years. There were 81 (35.2%), 54 (23.5%), 73 (31.7%) and 22 (9.6%) patients with RF levels between 20 and 50 IU/mL, 50 and 100 IU/mL, 100 and 500 IU/mL, and above 500 IU/mL, respectively. There was no significant difference detected between the groups that were created based on the RF titers regarding demographic characteristics (P > 0.05). The rate of being diagnosed with any rheumatic disease was significantly lower in the group with RF levels between 20 and 50 IU/mL compared to other groups (P = 0.001). The distribution of rheumatic and non-rheumatic disease diagnoses according to RF levels did not reveal any significant difference between the groups (P = 0.369 and P = 0.147, respectively). RA was the most common (62.2%) rheumatic disease diagnosis among the patients included in the study. The leukocyte count was significantly higher in the group with RF levels above 500 IU/mL compared to the group with RF levels between 20 and 50 IU/mL (P = 0.024). There was no significant difference between the groups in other laboratory results, that is, hemogram, sedimentation, C-reactive protein, platelet, and lymphocyte/monocyte ratio (P > 0.05).

CONCLUSION

The study findings indicate that RF positivity can be seen in the context of different rheumatological diseases; hence RF levels alone may not predict rheumatological disease. There was also no significant relationship between RF levels and ANA and anti-CCP positivity. The most common diagnosis in patients presenting with elevated RF levels was RA. Nevertheless, it should be noted that RF can be found asymptomatically in the general population.

Association of the serological status of rheumatoid arthritis patients with two circulating protein biomarkers: A useful tool for precision medicine strategies

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of the joints and presence of systemic autoantibodies, with a great clinical and molecular heterogeneity. Rheumatoid Factor (RF) and anti-citrullinated protein antibodies (ACPA) are routinely used for the diagnosis of RA. However, additional serological markers are needed to improve the clinical management of this disease, allowing for better patient stratification and the desirable application of precision medicine strategies. In the present study, we investigated those systemic molecular changes that are associated with the RF and ACPA status of RA patients. To achieve this objective, we followed a proteomic biomarker pipeline from the discovery phase to validation. First, we performed an iTRAQ-based quantitative proteomic experiment on serum samples from the RA cohort of the Hospital of Santiago de Compostela (CHUS). In this discovery phase, serum samples from the CHUS cohort were pooled according to their RF/ACPA status. Shotgun analysis revealed that, in comparison with the double negative group (RF-/ACPA-), the abundance of 12 proteins was altered in the RF+/ACPA+ pool, 16 in the RF+/ACPA- pool and 10 in the RF-/ACPA+ pool. Vitamin D binding protein and haptoglobin were the unique proteins increased in all the comparisons. For the verification phase, 80 samples from the same cohort were analyzed individually. To this end, we developed a Multiple Reaction Monitoring (MRM) method that was employed in a comprehensive targeted analysis with the aim of verifying the results obtained in the discovery phase. Thirty-one peptides belonging to 12 proteins associated with RF and/or ACPA status were quantified by MRM. In a final validation phase, the serum levels of alpha-1-acid glycoprotein 1 (A1AG1), haptoglobin (HPT) and retinol-binding protein 4 (RET4) were measured by immunoassays in the RA cohort of the Hospital of A Coruña (HUAC). The increase of two of these putative biomarkers in the double seropositive group was validated in 260 patients from this cohort (p = 0.009 A1AG1; p = 0.003 HPT). The increased level of A1AG1 showed association with RF rather than ACPA (p = 0.023), whereas HPT showed association with ACPA rather than RF (p = 0.013). Altogether, this study has allowed a further classification of the RA seropositive patients into two novel clusters: RF+A1AG+ and ACPA+HPT+. The determination of A1AG1 and HPT in serum would provide novel information useful for RA patient stratification, which could facilitate the effective implementation of personalized medicine in routine clinical practice.

Case Report: Rheumatoid meningitis with positive NMDAR antibody: A case treated with intravenous immunoglobulin

As a rare complication of rheumatoid arthritis (RA) in the central nervous system (CNS), rheumatoid meningitis (RM) mainly affects the meninges and has various clinical symptoms. The diagnostic and treatment approaches currently used are not practical. RM cases with positive NMDAR antibodies (Abs) have never been reported. In the present study, a 66-year-old man with a 1-year history of RA presented recurrent left lower limb weakness during activities for 1 month. The results showed that rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (ACPA) were positive in the serum, and NMDAR Abs were present in cerebrospinal fluid (CSF). Hyperintensity was observed in the leptomeninges of the right frontal and parietal lobes, and subtle hyperintensity was observed in the left frontal and parietal lobes, as indicated by brain MRI. A meningeal biopsy revealed non-specific inflammation with the absence of rheumatoid nodules. The patient was given IVIg on day 7 after admission. The clinical symptoms were relieved, the lesions were alleviated, and abnormal biochemical indicators were gradually recovered 1 week after initiation of the treatment, while NMDAR Abs were present in CSF even after treatment. After 5 months of follow-up, the patient’s serum and CSF ACPA and IL-6 levels were still high. The findings showed that brain MRI was adequate for the diagnosis of RM. ACPA and IL-6 might be the specific biomarkers for disease activity in RM. IVIg was effective as induction therapy for RM. Further studies should explore whether the presence of NMDAR Abs is associated with RM.

Nanopore-based disease diagnosis using pathogen-derived tryptic peptides from serum

Nanopore sensors have shown great utility in nucleic acid detection and sequencing approaches. Recent studies also indicate that current signatures produced by peptide-nanopore interactions can distinguish high purity peptide mixtures, but the utility of nanopore sensors in clinical applications still needs to be explored due to the inherent complexity of clinical specimens. To fill this gap between research and clinical nanopore applications, we describe a methodology to select peptide biomarkers suitable for use in an immunoprecipitation-coupled nanopore (IP-NP) assay, based on their pathogen specificity, antigenicity, charge, water solubility and ability to produce a characteristic nanopore interaction signature. Using tuberculosis as a proof-of-principle example in a disease that can be challenging to diagnose, we demonstrate that a peptide identified by this approach produced high-affinity antibodies and yielded a characteristic peptide signature that was detectable over a broad linear range, to detect and quantify a pathogen-derived peptide from digested human serum samples with high sensitivity and specificity. This nanopore signal distinguished serum from a TB case, non-disease controls, and from a TB-case after extended anti-TB treatment. We believe this assay approach should be readily adaptable to other infectious and chronic diseases that can be diagnosed by peptide biomarkers.

Analysis of Risk Factors for Rheumatoid Arthritis in Yunnan: A Small-Scale Case-Control Study

Objective

To study the risk factors of rheumatoid arthritis (RA) in Yunnan and provide reference for its clinical prevention and treatment.

Methods

From January 2014 to February 2022, a total of 249 RA patients who were admitted to the First People's Hospital of Yunnan Province were selected and 149 healthy people were selected as the controls. The medical records, clinical data of blood test results of anticyclic citrullinated polypeptide (anti-CCP) antibody, antikeratin antibody (AKA), and antiperinuclear factor (APF) were collected. Logistic regression and receiver operating curve (ROC) were used to analyze the correlation between blood anti-CCP antibody, AKA, and APF and the occurrence of RA.

Results

Univariate analysis showed that the age, proportion of hypertension, and diabetes patients in RA patients were significantly different from those in the control group (p < 0.05), but there was no statistical difference in sex (p > 0.05). The area under the curve (AUC) of the serum anti-CCP antibody level in the diagnosis of RA was 0.76 (95% CI: 0.72-0.81, p < 0.01), the sensitivity was 85.23%, the specificity was 61.45%, and the cutoff value was 18.07AU/mL. The positive rates of AKA (33.73%) and APF (43.37%) in the RA patients were significantly higher than those in the controls (4.03% and 6.04%), and the differences were statistically significant (p < 0.001). After adjusting for age, sex, hypertension, and diabetes, logistic regression analysis showed that anti-CCP positivity, AKA positive, and APF positive were all independent risk factors for RA (OR = 20.24, 95% CI: 9.36-43.77, p < 0.01; OR = 4.33, 95% CI: 1.62-11.60, p < 0.01; OR = 5.28, 95% CI: 2.33-11.99, p < 0.01).

Conclusion

Anti-CCP positive, AKA positive, and APF positive are independent risk factors for the occurrence of RA. Serum anti-CCP level has high sensitivity but low specificity in the diagnosis of RA.

Antibodies to Citrullinated Protein Antigens, Rheumatoid Factor Isotypes and the Shared Epitope and the Near-Term Development of Clinically-Apparent Rheumatoid Arthritis

Background/Purpose

In rheumatoid arthritis (RA) autoantibodies including antibodies to citrullinated protein antigens (ACPA) and rheumatoid factor (RF) can be predictive of incident clinical RA. However, there is limited understanding of how antibody changes over time impact prediction of the likelihood and timing of future clinical RA.

Materials and Methods

We evaluated relationships between ACPA, the shared epitope (SE), RF isotypes and incident RA in a prospective cohort of 90 ACPA(+) individuals without baseline arthritis identified through health-fair testing (i.e. Healthfair). We also evaluated ACPA and RF isotypes and time-to-diagnosis of RA in a retrospective cohort of 215 individuals with RA from the Department of Defense Serum Repository (DoDSR).

Results

Twenty-six of 90 (29%) of ACPA(+) Healthfair participants developed incident RA. Baseline or incident dual RF-IgA and RF-IgM positivity was associated with increased risk for incident RA (HR 3.09; 95% CI 1.15 to 8.29) although RFs were negative in ~50% of individuals with incident RA. SE was associated with increased risk of RA (HR 2.87, 95% CI 1.22-6.76). In the DoDSR cohort, triple positivity for ACPA, RF-IgA and RF-IgM was present a median of 1-2 years prior to RA diagnosis, with some sex-specific differences.

Conclusion

These findings can be used to counsel individuals at-risk for future RA and to design clinical trials for RA prevention. The findings also suggest that RF could be a surrogate outcome as a success of an immunologic intervention in RA prevention. Additional studies are needed to understand the biologic of different patterns of autoantibody elevations in RA evolution.

Prediction of Immune-Related Adverse Events Induced by Immune Checkpoint Inhibitors With a Panel of Autoantibodies: Protocol of a Multicenter, Prospective, Observational Cohort Study

Introduction: Immune checkpoint inhibitor (ICI) therapy is markedly improving the prognosis of patients with several types of cancer. On the other hand, the growth in the use of these drugs in oncology is associated with an increase in multiple immune-related adverse events (irAEs), whose optimal prevention and management remain unclear. In this context, there is a need for reliable and validated biomarkers to predict the occurrence of irAEs in patients treated with ICIs. Thus, the main objective of this study is to evaluate the diagnostic performance of a sensitive routinely available panel of autoantibodies consisting of antinuclear antibodies, rheumatoid factor, and antineutrophil cytoplasmic antibodies to identify patients at risk of developing irAEs.

Methods and Analysis: A multicenter, prospective, observational, cohort study has been designed to be conducted in patients diagnosed with cancer amenable to ICI therapy. Considering the percentage of ICI-induced irAEs to be 25% and a loss to follow-up of 5%, it has been estimated that a sample size of 294 patients is required to detect an expected sensitivity of the autoantibody panel under study of 0.90 with a confidence interval (95%) of no less than 0.75. For 48 weeks, patients will be monitored through the oncology outpatient clinics of five hospitals in Spain. Immune-related adverse events will be defined and categorized according to CTCAE v. 5.0. All the patients will undergo ordinary blood tests at specific moments predefined per protocol and extraordinary blood tests at the time of any irAE being detected. Ordinary and extraordinary samples will be frozen and stored in the biobank until analysis in the same autoimmunity laboratory when the whole cohort reaches week 48. A predictive model of irAEs will be constructed with potential risk factors of immune-related toxicity including the autoantibody panel under study.

Ethics and Dissemination: This protocol was reviewed and approved by the Ethical Committee of the Basque Country and the Spanish Agency of Medicines and Medical Devices. Informed consent will be obtained from all participants before their enrollment. The authors declare that the results will be submitted to an international peer-reviewed journal for their prompt dissemination.

Structure of type II collagen from sturgeon cartilage and its effect on adjuvant-induced rheumatoid arthritis in rats

The purpose of this paper was to extract and characterize type II collagen of sturgeon cartilage (SC-CII), and to explore the effects of taking SC-CII orally on rheumatoid arthritis (RA) in rats. SC-CII showed a triple-helix structure (RPN = 0.12), with d1 of 11.82 Å and d2 of 4.08 Å, which was analyzed by FT-IR, CD, XRD, and MS. It was constructed of the repeating tripeptide unit Gly-X-Y, where X and Y are generally Pro or Hyp, proved by amino acid composition and peptide mass fingerprinting. Furthermore, the effects of SC-CII on RA were evaluated. Ankle thickness was significantly decreased in SC-CII groups, with changes in lymphocyte proliferation also observed. Compared with the model control group, there was an evident decrease in TNF-α, IL-1β, COX-2, MCP-1, and TLR-4 mRNA levels, but no remarkable differences in APF, MMP-3, and MyD88 mRNA levels in the SC-CII groups. In addition, TNF-α, IL-1β, RF, Anti-CII Ab were significantly reduced in the SC-CII groups, proved by ELISA. Therefore, SC-CII showed alleviating effects on RA through the TLR4/MyD88-NFκB pathway.

From risk to chronicity: evolution of autoreactive B cell and antibody responses in rheumatoid arthritis

The presence of disease-specific autoantibody responses and the efficacy of B cell-targeting therapies in rheumatoid arthritis (RA) indicate a pivotal role for B cells in disease pathogenesis. Important advances have shaped our understanding of the involvement of autoantibodies and autoreactive B cells in the disease process. In RA, autoantibodies target antigens with a variety of post-translational modifications such as carbamylation, acetylation and citrullination. B cell responses against citrullinated antigens generate anti-citrullinated protein antibodies (ACPAs), which are themselves modified in the variable domains by abundant N-linked glycans. Insights into the induction of autoreactive B cells against antigens with post-translational modifications and the development of autoantibody features such as isotype usage, epitope recognition, avidity and glycosylation reveal their relationship to particular RA risk factors and clinical phenotypes. Glycosylation of the ACPA variable domain, for example, seems to predict RA onset in ACPA⁺ healthy individuals, possibly because it affects B cell receptor signalling. Moreover, ACPA-expressing B cells show dynamic phenotypic changes and develop a continuously proliferative and activated phenotype that can persist in patients who are in drug-induced clinical remission. Together, these findings can be integrated into a conceptual framework of immunological autoreactivity in RA, delineating how it develops and persists and why disease activity recurs when therapy is tapered or stopped.

Proteoform Analysis of Matrix Metalloproteinase-9/Gelatinase B and Discovery of Its Citrullination in Rheumatoid Arthritis Synovial Fluids

Objectives

To explore posttranslational modifications (PTMs), including proteolytic activation, multimerization, complex formation and citrullination of gelatinases, in particular of gelatinase B/MMP-9, and to detect in gelatin-Sepharose affinity-purified synovial fluids, the presence of specific MMP proteoforms in relation to arthritis.

Methods

Latent, activated, complexed and truncated gelatinase-A/MMP-2 and gelatinase B/MMP-9 proteoforms were detected with the use of zymography analysis to compare specific levels, with substrate conversion assays, to test net proteolytic activities and by Western blot analysis to decipher truncation variants. Citrullination was detected with enhanced sensitivity, by the use of a new monoclonal antibody against modified citrullines.

Results

All MMP-9 and MMP-2 proteoforms were identified in archival synovial fluids with the use of zymography analysis and the levels of MMP-9 versus MMP-2 were studied in various arthritic diseases, including rheumatoid arthritis (RA). Secondly, we resolved misinterpretations of MMP-9 levels versus proteolytic activities. Thirdly, a citrullinated, truncated proteoform of MMP-9 was discovered in archival RA synovial fluid samples and its presence was corroborated as citrullinated hemopexin-less MMP-9 in a small prospective RA sample cohort.

Conclusion

Synovial fluids from rheumatoid arthritis contain high levels of MMP-9, including its truncated and citrullinated proteoform. The combination of MMP-9 as analyte and its PTM by citrullination could be of clinical interest, especially in the field of arthritic diseases.

Periodontitis and rheumatoid arthritis: What have we learned about their connection and their treatment?

Rheumatoid arthritis and periodontitis are chronic inflammatory diseases defined respectively by the destruction of the articular cartilage and tooth-supporting periodontal tissues. Although the epidemiologic evidence for an association between these two diseases is still scarce, there is emerging scientific information linking specific bacterial periodontal pathogens, such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, in the citrullination process, leading to autoantibody formation and compromised immunotolerance of the susceptible patient to rheumatoid arthritis. In this review, we update the existing information on the evidence, not only regarding the epidemiologic association, but also the biologic mechanisms linking these two diseases. Finally, we review information emerging from intervention studies evaluating whether periodontal treatment could influence the initiation and progression of rheumatoid arthritis.

Resting-state EEG for the diagnosis of idiopathic epilepsy and psychogenic nonepileptic seizures: A systematic review

Quantitative markers extracted from resting-state electroencephalogram (EEG) reveal subtle neurophysiological dynamics which may provide useful information to support the diagnosis of seizure disorders. We performed a systematic review to summarize evidence on markers extracted from interictal, visually normal resting-state EEG in adults with idiopathic epilepsy or psychogenic nonepileptic seizures (PNES). Studies were selected from 5 databases and evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2. 26 studies were identified, 19 focusing on people with epilepsy, 6 on people with PNES, and one comparing epilepsy and PNES directly. Results suggest that oscillations along the theta frequency (4-8 Hz) may have a relevant role in idiopathic epilepsy, whereas in PNES there was no evident trend. However, studies were subject to a number of methodological limitations potentially introducing bias. There was often a lack of appropriate reporting and high heterogeneity. Results were not appropriate for quantitative synthesis. We identify and discuss the challenges that must be addressed for valid resting-state EEG markers of epilepsy and PNES to be developed.

Rheumatoid arthritis-interstitial lung disease: manifestations and current concepts in pathogenesis and management

Rheumatoid arthritis (RA) is a systemic inflammatory disorder, with the most common extra-articular manifestation of RA being lung involvement. While essentially any of the lung compartments can be affected and manifest as interstitial lung disease (ILD), pleural effusion, cricoarytenoiditis, constrictive or follicular bronchiolitis, bronchiectasis, pulmonary vasculitis, and pulmonary hypertension, RA-ILD is a leading cause of death in patients with RA and is associated with significant morbidity and mortality. In this review, we focus on the common pulmonary manifestations of RA, RA-ILD and airway disease, and discuss evolving concepts in the pathogenesis of RA-associated pulmonary fibrosis, as well as therapeutic strategies, and have revised our previous review on the topic. A rational clinical approach for the diagnosis and management of RA-ILD, as well as an approach to patients with clinical worsening in the setting of treatment with disease-modifying agents, is included. Future directions for research and areas of unmet need in the realm of RA-associated lung disease are raised.

Rheumatoid arthritis (RA) is a systemic inflammatory disorder, with the most common extra-articular manifestation of RA being lung involvement. RA-ILD is a leading cause of death in RA patients and is associated with significant morbidity and mortality.https://bit.ly/3w6oY4i

Combining Calcitonin and Procalcitonin and Rheumatoid Arthritis-Related Biomarkers Improve Diagnostic Outcomes in Early Rheumatoid Arthritis

Objective

To demonstrate whether procalcitonin (PCT) combined with calcitonin (CT) could provide additional diagnostic value to other clinically available rheumatoid arthritis- (RA-) related biomarkers in the early diagnosis of RA.

Method

The blood samples aseptically collected by venipuncture were centrifuged within 1 hour and frozen at -80°C. PCT and CT levels were measured using electrochemiluminescence immunoassay (ECLIA) in 260 subjects (48 patients with early RA, 34 patients with established RA, 37 patients with systemic lupus erythematosus, 30 with osteoarthritis, 31 with gouty arthritis, and 80 healthy participants). Anti-cyclic citrullinated peptide (Anti-CCP) and anti-RA33 antibodies (Anti-RA33) were analyzed by ELISA. RF was detected by transmission immunoturbidimetry. Mann-Whitney U tests and Kruskal-Wallis tests compared differences among groups. Spearman's rank correlation analysis determined the relationship between biomarkers. Receiver-operator characteristic (ROC) curves were generated, and diagnostic performance was assessed by area under the curve (AUC), as well as specificity, sensitivity, likelihood ratios (LR).

Results

Median serum PCT concentrations were significantly higher (p < 0.0001) in patients with early RA (0.065 ng/ml) when compared with healthy controls (0.024 ng/ml), and patients with osteoarthritis (0.025 ng/ml). When compared with gouty arthritis (GA) controls (0.072 ng/ml) and systemic lupus erythematosus (SLE) controls (0.093 ng/ml), median serum PCT concentrations were not significant in patients with early RA (0.065 ng/ml). Median serum CT concentrations were significantly lower (p < 0.0001) in patients with early RA (0.880 pg/ml) compared with healthy controls (3.159 pg/ml), patients with SLE (2.480 pg/ml), and patients with GA (2.550 pg/ml). When compared with osteoarthritis controls (0.586 pg/ml), median serum CT concentrations were not significant in patients with early RA (0.880 pg/ml). ROC curve analysis comparing early RA with healthy controls demonstrated that the AUC of RF, anti-CCP, and anti-RA33 were 0.66, 0.73, and 0.64, respectively; the additions of PCT and CT further improved the diagnostic ability of early RA with the AUC of 0.97, 0.98, and 0.97, respectively (p < 0.01). The sensitivities of RF, anti-CCP, and anti-RA33 for early RA were 33.33%, 44.74%, and 58.33%, respectively, and the additions of PCT and CT showed very high sensitivities of 83.33%, 92.11%, and 87.50%. The high-value groups of PCT moderately correlated with the anti-RA33 levels (r = 0.417, p < 0.05). CT had no significant correlation with disease duration, radiographic progression, or clinical/serological variables, such as ESR levels, CRP levels, RF, anti-CCP, and anti-RA33 levels in early RA.

Conclusions

Serum PCT and CT combined with clinically available RA-related biomarkers could further improve the diagnostic efficiency of early RA.

Biomarkers in Rheumatoid Arthritis

The utilization and identification of biomarkers in rheumatoid arthritis (RA) to facilitate timely diagnosis and the optimal management of the disease is an area of active investigation. This review focuses on biomarkers available for routine clinical use, details potential investigational biomarkers, and raises outstanding clinical questions.

Digital foot health technology and diabetic foot monitoring: A systematic review

BACKGROUND

In diabetic foot ulceration, a correlation between pressure and skin temperature is suspected. The aim of this systematic review is to provide a more rigorous analysis of existing literature related to the various technologies used to read and measure both in-shoe plantar pressures, and in-shoe skin temperatures simultaneously.

METHODS

A systematic review of the literature related to the topic was searched in database sources such as Medline OVID, Cochrane Library, PubMed, CONAHL, PROSPERO, and Elsevier. Outcome measures of interest included validity, reliability and responsiveness of in-shoe temperature and/or pressure mapping device used, and characteristics and quantity of sensors used, anatomical landmarks and statistical analysis used to interpret the data. Quality of evidence and risk of bias was evaluated using the QUADAS-2.

RESULTS

Nineteen studies were identified and included in this review. The majority of studies used a small sample size (mean n = 17) and recruited healthy participants. All studies have shown excellent validity but only a few tested for the reliability of the device. None of the studies tested for responsiveness of the device. Quality assessment results scored high risk in view of 'patient selection', 'use of reference standard' and 'applicability', and low risk in view of 'use if index test' and 'flow and timing'.

CONCLUSIONS

The data outlined in this review confirms that further improvement, reliability testing and clinical validation of the developed systems is required despite the results of excellent performance in detecting changes of in-shoe skin temperature and pressure.

Arthroplasty Rates Not Increasing in Young Patients With Rheumatoid Arthritis: A National Database Review, 2005 Versus 2014

Background

For 20 years, authors have predicted an expansion in total knee arthroplasty (TKA) and total hip arthroplasty (THA) utilization. Over this same period, the introduction of biological disease-modifying antirheumatic drugs has dramatically altered the treatment of rheumatoid arthritis (RA) with hopes of preventing articular damage and obviating the need for prosthetic replacement. The goal of our investigation was to evaluate TKA and THA utilization in young patients with RA (<65 years) in 2005 vs 2014 compared to patients with osteoarthritis (OA).

Methods

Using relevant International Classification of Disease Ninth Revision (ICD-9) and Current Procedural Terminology codes, the Truven MarketScan Database (over 46 million enrollees) was queried to determine THA and TKA incidence rates for RA and OA patients aged <65 years during the final decade of ICD-9 use. Patients with potentially confounding ICD-9 codes were excluded to limit coding variation. Statistical analysis consisted of student t-tests, Pearson's chi-square tests, and Breslow-Day tests.

Results

For patients with OA, TKAs increased substantially from 0.07% in 2005 to 0.1% in 2014 (+42.9% change, P < .001). Similarly for patients with OA, THAs increased from 0.04% to 0.06% over the same time period (+66.0% change, P < .001). For young patients with RA, the rate of TKA remained relatively stable—1.06% in 2005 to 1.04% in 2014 (−1.7% change, P = .65)—as did THA—0.44% to 0.48% (+9.0% change, P = .14).

Conclusions

Dramatic increases in THA and TKA rates for OA patients aged <65 years were indeed observed from 2005 to 2014. This trend, however, was not seen in the RA population where TKA and THA rates remained unchanged.

Fluctuation in anti-cyclic citrullinated protein antibody level predicts relapse from remission in rheumatoid arthritis: KURAMA cohort

Background

The positivity of anti-citrullinated protein/peptide antibodies (ACPAs) is a clinically useful diagnostic and prognostic marker in rheumatoid arthritis (RA). However, the significance of ACPA titer and its fluctuation remain unclear. This study aimed to assess the role of ACPA titer and its fluctuation on disease activity and the prognosis of RA.

Methods

Data obtained from the Kyoto University Rheumatoid Arthritis Management Alliance (KURAMA) cohort was analyzed. Patients whose ACPA was measured at least twice between 2011 and 2019 and whose ACPA was positive at least once were included in this study. The association between the clinical variable and ACPA titer or its change was investigated.

Results

ACPA titer was measured in a total of 3286 patients, 1806 of whom were ACPA-positive at least once. Among them, the ACPA titer level was measured more than once in 1355 patients. Very weak correlation was observed between the ACPA titer level and disease activity. Additionally, there was no trend in the fluctuation of ACPA titer level in each patient; ACPA titer level fluctuated in some patients, but not in others. Patients with high variable levels of ACPA titer were more likely to relapse from remission. In the analysis of two consecutive ACPA measurements, the titer changes predicted the relapse from remission within a year of the second measurement.

Conclusions

The ACPA titer level fluctuated in some patients. Very weak correlation was observed between the ACPA titer level and disease activity. Fluctuation in ACPA titer level predicted relapse from remission in patients with RA.

Supplementary information

The online version contains supplementary material available at 10.1186/s13075-020-02366-x.

Diagnostic accuracy of 14-3-3 η protein in rheumatoid arthritis: A meta-analysis

AIM

To evaluate the overall diagnostic performance of 14-3-3 η protein in patients with rheumatoid arthritis (RA).

METHODS

PubMed, EMBASE, and Web of Science were searched to acquire eligible studies. Articles published in English before 20 February 2020 were included. Quality Assessment of Diagnostic Accuracy Studies 2 was used to evaluate the risk of bias and application concern of the included articles. Pooled analysis of diagnostic indicators of 14-3-3 η protein for RA was conducted by using a random effects model. Subgroup analysis was used to explore the sources of heterogeneity. Deeks' funnel plot asymmetry test was used to evaluate for the presence of publication bias.

RESULTS

A total of 13 studies (1554 positive and 1934 negative participants) were included. The pooled sensitivity and specificity were 0.73 (95% CI 0.71-0.75) and 0.88 (95% CI 0.87-0.90), respectively. The pooled positive/negative likelihood were 5.98 (95% CI 4.39-8.14) and 0.28 (95% CI 0.21-0.37), respectively. In addition, the pooled diagnostic odds ratio was 23.48 (95% CI 13.76-40.08) and the area under curve was 0.9245. The results of subgroup analysis indicated that ethnicity and control group might be the source of heterogeneity. The results of sensitivity analysis were stable. No significant publication bias was found.

CONCLUSIONS

The current evidence indicated that 14-3-3 η protein has moderate accuracy for the diagnosis of RA.

Comprehensive Bioinformatics Analysis Reveals Hub Genes and Inflammation State of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by erosive arthritis, which has not been thoroughly cured yet, and standardized treatment is helpful for alleviating clinical symptoms. Here, various bioinformatics analysis tools were comprehensively utilized, aiming to identify critical biomarkers and possible pathogenesis of RA. Three gene expression datasets profiled by microarray were obtained from GEO database. Dataset GSE55235 and GSE55457 were merged for subsequent analyses. We identified differentially expressed genes (DEGs) in RStudio with limma package, performing functional enrichment analysis based on GSEA software and clusterProfiler package. Next, protein-protein interaction (PPI) network was set up through STRING database and Cytoscape. Moreover, CIBERSORT website was used to assess the inflammatory state of RA. Finally, we validated the candidate hub genes with dataset GSE77298. As a result, we identified 106 DEGs (72 upregulated and 34 downregulated genes). Through GO, KEGG, and GSEA analysis, we found that DEGs were mainly involved in immune response and inflammatory signaling pathway. With the help of Cytoscape software and MCODE plug-in, the most prominent subnetwork was screened out, containing 14 genes and 45 edges. For ROC curve analysis, eight genes with AUC >0.80 were considered as hub genes of RA. In conclusion, compared with healthy controls, the DEGs and their closely related biological functions were analyzed, and we held that chemokines and immune cells infiltration promote the progression of rheumatoid arthritis. Targeting the eight biomarkers we identified may be useful for the diagnosis and treatment of rheumatoid arthritis.

T follicular helper cell subsets: a potential key player in autoimmunity

Follicular helper T (Tfh) cells are one of CD4+ helper T subsets which promote B cell maturation, activation and antigen-specific antibody production. Autoantibodies are hallmarks of autoimmune diseases, and crucial contributions of Tfh cells in development of these diseases are now evident. Deregulation of Tfh activities can contribute to a pathogenic autoantibody production and can play an important role in the promotion of autoimmune diseases. These days multiple researchers reported three subpopulations which has distinct effector functions in Tfh cells: Tfh1, Tfh2 and Tfh17 cells. In this review, we summarize the observed alterations in whole Tfh cells and subset distribution during autoimmune diseases.

Sensitivity and specificity of Interleukin 29 in patients with rheumatoid arthritis and other rheumatic diseases

BACKGROUND

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic and progressive inflammation that can cause a high degree of disability in affected individuals. Proinflammatory cytokines play central roles in the development of degradative and inflammatory responses in RA. IL-29 has been identified in RA and reported as a biomarker of the disease.

OBJECTIVE

To analyze serum levels and accuracy of IL-29 in RA patients compared to healthy subjects and patients with other rheumatic diseases.

METHODS

IL-29 serum levels were measured in 121 patients with RA, 53 patients with systemic lupus erythematosus (SLE), 60 patients with systemic sclerosis (SSc), 29 patients with fibromyalgia (FM), 50 patients with osteoarthritis (OA) and 68 healthy individuals as controls. IL-29 levels in serum were investigated by ELISA. Sensitivity, specificity and likelihood ratios (LR) for having RA were calculated.

RESULTS

Serum levels of IL-29 were increased in RA patients 113.6 (IQR = 31.25-308.5) pg/ml compared to non-RA patients (SLE, SSc, OA, and FM) (31.25 pg/ml) and healthy controls (31.25 pg/ml, p < 0.001). The IL-29 cut-off values to distinguish patients with RA from non-RA patients were 61.11 pg/ml (sensitivity 57.02, specificity 92.71, LR: 7.82) and for all subjects 32.96 pg/ml (sensitivity 64.46, specificity 87.31, LR: 5.08). Additionally, IL-29 correlated negatively with age (r=-0189, p = 0.038) and disease duration (-0.192, p = 0.037). Interestingly, IL-29 correlated positively with neutrophil count in RA patients positive for rheumatoid factor (r = 0.259, p = 0.022).

CONCLUSION

IL-29 is higher in the serum of patients with RA compared to non-RA subjects and may have potential for use as a biological marker.

Evidence of Diagnostic and Treatment Delay in Seronegative Rheumatoid Arthritis: Missing the Window of Opportunity

OBJECTIVES

To compare the time from first joint swelling to fulfillment of the American College of Rheumatology/European League Against Rheumatism classification criteria between patients with seropositive and seronegative rheumatoid arthritis (RA) and to assess the impact of seronegative status on the time from first joint swelling to initiation of disease-modifying antirheumatic drug (DMARD) therapy and achievement of remission.

PATIENTS AND METHODS

Times from first provider-documented joint swelling to fulfillment of the 1987 and 2010 American College of Rheumatology/European League Against Rheumatism criteria and to the clinical diagnosis of RA were measured in a population-based cohort of adults with incident RA between January 1, 2009, and December 31, 2014. Disease characteristics and achievement of remission were compared between seropositive (rheumatoid factor positive and/or anti-citrullinated peptide antibody positive) and seronegative (rheumatoid factor negative/anti-citrullinated peptide antibody negative) patients.

RESULTS

The median time from first joint swelling to fulfillment of the 1987 (48 [interquartile range (IQR), 0-300] days vs 2 [IQR, 0-45] days; P=.001) and 2010 (14 [IQR, 0-196] days vs 0 [IQR, 0-29] days; P=.004) classification criteria and the median time from first joint swelling to the clinical diagnosis of RA (187 [IQR, 13-503] days vs 11 [IQR, 0-76] days; P<.001) were significantly longer in seronegative patients than in seropositive patients. The median time from first joint swelling to first prescribed DMARD therapy was significantly longer in seronegative patients (40 [IQR, 5-199] days vs 14 [IQR, 0-73] days; P=.01). Patients with seronegative RA were less likely to achieve remission (28% vs 50% at 5 years after fulfillment of the 2010 criteria; P=.007), but there was no difference when the patient global score was removed from the remission definition.

CONCLUSION

Patients with seronegative RA experienced a delay in diagnosis, according to both the 1987 and 2010 classification criteria, as well as a delay in the initiation of DMARD therapy. Patients with seronegative RA were also less likely to attain remission, suggesting that the window of opportunity for intervention may be more frequently missed in this group.

Polymyalgia Rheumatica and Seronegative Elderly-Onset Rheumatoid Arthritis: Two Different Diseases with Many Similarities

Polymyalgia rheumatica (PMR) and seronegative elderly-onset rheumatoid arthritis (SEORA) are two of the most frequent inflammatory rheumatologic diseases in elderly patients. At first presentation, there are many similarities between PMR and SEORA, that may lead to a real diagnostic conundrum. The most relevant similarities and differences between PMR and SEORA are discussed in this review. In addition to the acute involvement of the shoulder joints, important features characterising both diseases are morning stiffness longer than 45 minutes, raised erythrocyte sedimentation rate, and a good response to low doses of prednisone. Some findings (such as erosive arthritis or symmetrical involvement of metacarpophalangeal and/or proximal interphalangeal joints) can help to make the diagnosis of SEORA, whereas shoulder and hip ultrasonography and 18-FDG PET/CT seem to be less specific. However, in several patients only long-term follow-ups confirm the initial diagnosis. A definite diagnosis of PMR or SEORA has significant therapeutic implications, since patients with PMR should be treated with long-term glucocorticoids, and sometimes throughout life, which predisposes the patients to serious side effects. On the contrary, in patients with SEORA, short-term treatment with glucocorticoids should be considered when initiating or changing disease modifying antirheumatic drugs, followed by rapid tapering.

Malondialdehyde-Acetaldehyde Adducts and Antibody Responses in Rheumatoid Arthritis-Associated Interstitial Lung Disease

OBJECTIVE

To compare serum anti-malondialdehyde-acetaldehyde (anti-MAA) antibody levels and MAA expression in lung tissue from patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD) to those found in controls.

METHODS

Anti-MAA antibody (IgA, IgM, IgG) concentrations were measured in patients with RA-ILD and compared to those of RA patients with chronic obstructive pulmonary disease (COPD) and RA patients without lung disease. Associations between anti-MAA antibody with RA-ILD were assessed using multivariable logistic regression. Lung tissue from patients with RA-ILD, other ILD, or emphysema, and from controls (n = 3 per group) were stained for MAA, citrulline, macrophages (CD68), T cells (CD3), B cells (CD19/CD27), and extracellular matrix proteins (type II collagen, fibronectin, vimentin). Tissue expression and colocalization with MAA were quantified and compared.

RESULTS

Among 1,823 RA patients, 90 had prevalent RA-ILD. Serum IgA and IgM anti-MAA antibody concentrations were higher in RA-ILD than in RA with COPD or RA alone (P = 0.005). After adjustment for covariates, the highest quartiles of IgA anti-MAA antibody concentration (odds ratio 2.09 [95% confidence interval 1.11-3.90]) and IgM (odds ratio 2.23 [95% confidence interval 1.19-4.15]) were significantly associated with the presence of RA-ILD. MAA expression in RA-ILD lung tissue was greater than in tissue from all other groups (P < 0.001), and it colocalized with citrulline (r = 0.79), CD19+ B cells (r = 0.78), and extracellular matrix proteins (type II collagen [r = 0.72] and vimentin [r = 0.77]) to the greatest degree in RA-ILD.

CONCLUSION

Serum IgA and IgM anti-MAA antibody is associated with ILD among RA patients. MAA is highly expressed in RA-ILD lung tissue, where it colocalizes with other RA autoantigens, autoreactive B cells, and extracellular matrix proteins, highlighting its potential role in the pathogenesis of RA-ILD.

Potential involvement of OX40 in the regulation of autoantibody sialylation in arthritis

OBJECTIVE

An increased proportion of circulating follicular helper T (Tfh) cells was reported in rheumatoid arthritis (RA), but it remains uncertain how Tfh cells affect antibody hyposialylation. We investigated the regulation of autoantibody hyposialylation by Tfh cells in RA using murine model.

METHODS

Behaviours of Tfh cells and their function on B cell promotion were analysed. Change of arthritogenicity and sialylation of autoantibodies during the course of arthritis was examined by mass spectrometry. Tfh-mediated regulation of hyposialylation was investigated, and the responsible cell surface molecule was specified both in vitro and in vivo. The relation between circulating Tfh cells and hyposialylation was analysed in patients with RA.

RESULTS

An increase in Tfh, particularly interleukin-17 producing Tfh (Tfh17) cells, at the onset of arthritis and their enhancement of autoantibody production were found. Autoantibodies at the onset phase demonstrated stronger inflammatory properties than those at the resolution phase, and mass spectrometric analysis revealed their difference in sialylation. In vitro coculture showed enhanced hyposialylation by the Tfh cells via OX40, which was highly expressed in the Tfh and Tfh17 cells. Blockade of OX40 prevented the development of arthritis with reduction in Tfh17 cells and recovery of autoantibody sialylation. Analysis of patients with RA showed abundance of OX40-overexpressing Tfh17 cells, and their proportion correlated negatively with the expression of α2,6-sialyltransferase 1, an enzyme responsible for sialylation.

CONCLUSIONS

OX40 expressed on Tfh cells can regulate autoantibody sialylation and play a crucial role in the development of autoimmune arthritis.

Association of Changes in Anticitrullinated Protein Antibody Levels With Resource Use and Disease Activity Measures in Rheumatoid Arthritis Patients a US Observational Cohort

PURPOSE

Anticitrullinated protein antibody (ACPA) concentration, beyond ACPA positivity, is indicative of more aggressive radiographic progression in patients with rheumatoid arthritis (RA). However, there is limited information on the association of changes in ACPA with resource use measures and/or disease activity measures. We evaluate associations between changes in levels of ACPA and outcomes, including durable medical equipment (DME) use, hospitalizations, and disease activity, in patients with established RA.

METHODS

Patients from the Brigham and Women's Hospital Rheumatoid Arthritis Sequential Study who had ACPA measurements at baseline and month 12 were included. Changes in ACPA levels from baseline to month 12 were categorized as a decrease (<-10%), no change (-10% to +10%), or increase (>+10%). DME use and hospitalizations were assessed twice yearly using patient questionnaires; disease activity was assessed annually. Binary multivariate logistic regression was used to analyze the association between changes in ACPA levels and DME use and hospitalizations; linear regression was used to assess the association with disease activity.

FINDINGS

Of 840 patients included in the analysis, 291 (34.6%), 266 (31.7%), and 283 (33.7%) had a decrease, no change, or increase in ACPA levels, respectively. A decrease in ACPA levels was associated with a reduction in DME use (adjusted odds ratio [aOR] = 0.64; 95% CI, 0.44-0.93; P = 0.02) and hospitalizations (aOR = 0.62; 95% CI, 0.41-0.95; P = 0.03) versus no change or increase. Adjusted mean changes in disease activity score in 28 joints (C-reactive protein), total and swollen joint counts, and pain scores were significantly greater in patients with decreased ACPA levels versus those with no change or increase (P < 0.05).

IMPLICATIONS

Among patients with RA, reductions in ACPA levels of >10% were associated with reductions in DME use, hospitalizations, and disease activity. ClinicalTrials.gov identifier: NCT01793103.

Serum Citrulline Levels Exhibit Circadian Variation and Fluctuations in Relation to Food Intake in Mice

Background

Plasma citrulline is a nonessential amino acid synthesized almost exclusively by enterocytes of the small intestine. Correlation between post-operative plasma citrulline levels and remnant small bowel mass and function has led to its use as a simple biomarker of functional intestinal mass in adults and children, with a proposed prognostic value for achieving enteral autonomy in the setting of intestinal failure. While it is standard to measure fasting levels in humans, the optimal timing of blood draws in relation to food intake and time of day has not been standardized and is poorly studied in animal models. We hypothesize that serum citrulline levels vary both throughout the day and with relation to food intake in mice.

Methods

Serum citrulline levels were measured from 12 C57BL/6 mice (6 - 9 weeks old) in the mornings and evenings, either after ad libitum food intake or after 8 - 12 h of access to water only. Blood draws for each experimental set-up were performed 1 week apart according to our Institutional Animal Care and Use Committee (IACUC) guidelines for acceptable blood collection volumes for survival procedures. At the end of the experiment, mice were euthanized and small intestine was harvested for morphometric measurements. Group means were compared using Student’s t-test with significance assumed for P < 0.05.

Results

After withholding chow for 8 - 12 h, serum citrulline levels were significantly greater in the morning compared to levels drawn in the evening. When mice were allowed ad libitum chow, there was no significant difference in serum citrulline levels drawn in the morning compared to the evening. There was no difference detected in villus height across the different experimental conditions.

Conclusions

Serum citrulline levels exhibit circadian variation and fluctuations in relation to food intake in mice, without apparent concurrent changes in enterocyte mass. There was no diurnal variation of serum citrulline levels in fed mice whereas fasted mice had significantly higher levels of serum citrulline in the morning compared to the evening. These findings underscore the paramount importance of consistent sample collection strategies in the setting of translational research.

Economic Evaluation of Anticyclic Citrullinated Peptide Positivity in Rheumatoid Arthritis

BACKGROUND

Anticyclic citrullinated peptide (anti-CCP) positivity may be a strong predictor of joint erosion and a potential biomarker for guiding treatment decisions for rheumatoid arthritis (RA). However, limited studies are currently available on the effect of anti-CCP positivity on health care utilization and/or medical costs of RA patients.

OBJECTIVE

To investigate short-term and long-term direct health care expenditures associated with anti-CCP positivity in newly diagnosed RA patients.

METHODS

A retrospective cohort study was conducted in adult RA patients within a U.S. integrated health care delivery system (January 1, 2007-June 30, 2015). Patients were required to have 2 RA diagnoses and treatment with a conventional or biologic disease-modifying antirheumatic drug (DMARD) within 12 months. The first RA diagnosis date was labeled as the index date, and patients were followed until they left the health plan, died, or reached the end of the study period. Patient demographics, anti-CCP results, comorbid conditions, and health care resource utilization during baseline (12 months before the index date) and follow-up periods were collected. Nationally recognized direct medical costs were assigned to health care utilization to calculate health care costs in 2015 U.S. dollars. The baseline differences between anti-CCP positivity and negativity and differences in censoring during follow-up were addressed using propensity scores. The mean differences in costs were estimated using recycled prediction methods.

RESULTS

2,448 newly diagnosed RA patients were identified and followed for a median of 3.7 years (range = 1-8 years). At baseline, 65.8% of patients were anti-CCP positive. Anti-CCP-positive patients had fewer comorbid conditions at baseline. During the first 12 months of follow-up, median (interquartile range) total health care expenditures for anti-CCP-positive and anti-CCP-negative patients were $6,200 ($3,563-$13,260) and $7,022 ($3,885-$12,995), respectively. After adjusting for baseline differences, total incremental mean cost associated with anti-CCP positivity during the first 12 months was estimated to be $2,163 per patient (P = 0.001). The annual incremental costs in anti-CCP-positive patients became progressively larger over time, from $2,163 during the first year to $5,062 during the fourth year. Anti-CCP positivity was associated with higher prescription, laboratory testing, and rheumatologist utilization. A higher percentage of anti-CCP-positive patients received 1 or more biologic DMARDs (11.6% for anti-CCP-positive vs. 5.7% for anti-CCP negative; P < 0.001) compared with anti-CCP-negative patients during the 12-month follow-up, which resulted in $2,499 in incremental prescription costs (P < 0.001). Total additional burden associated with anti-CCP positivity during the first 4 years was estimated to be $14,089 per patient.

CONCLUSIONS

In newly diagnosed RA patients, higher economic burden associated with anti-CCP positivity was mainly driven by prescription costs.

DISCLOSURES

This research and manuscript were funded by Bristol-Myers Squibb (BMS). Alemao and Connolly are employees and shareholders of BMS and participated in the design of the study, interpretation of the data, review/revision of the manuscript, and approval of the final version of the manuscript. An and Cheetham received a grant from BMS for this research. At the time of this study, An was employed by Western University of Health Sciences, and Cheetham was employed by Kaiser Permanente Southern California. Bider-Canfield, Kang, and Lin have nothing to disclose. Some study results were presented as a poster at the American College of Rheumatology Annual Meeting; November 5, 2017; San Diego, CA, and at the International Society for Pharmacoeconomics and Outcomes Research Meeting; May 19, 2018; Baltimore, MD.

Cardiac phenotype in mouse models of systemic autoimmunity

Patients suffering from systemic autoimmune diseases are at significant risk of cardiovascular complications. This can be due to systemically increased levels of inflammation leading to accelerated atherosclerosis, or due to direct damage to the tissues and cells of the heart. Cardiac complications include an increased risk of myocardial infarction, myocarditis and dilated cardiomyopathy, valve disease, endothelial dysfunction, excessive fibrosis, and bona fide autoimmune-mediated tissue damage by autoantibodies or auto-reactive cells. There is, however, still a considerable need to better understand how to diagnose and treat cardiac complications in autoimmune patients. A range of inducible and spontaneous mouse models of systemic autoimmune diseases is available for mechanistic and therapeutic studies. For this Review, we systematically collated information on the cardiac phenotype in the most common inducible, spontaneous and engineered mouse models of systemic lupus erythematosus, rheumatoid arthritis and systemic sclerosis. We also highlight selected lesser-known models of interest to provide researchers with a decision framework to choose the most suitable model for their study of heart involvement in systemic autoimmunity.