Cytokines, autoantibodies and viral antibodies in premorbid and postdiagnostic sera from patients with rheumatoid arthritis: case-control study nested in a cohort of Norwegian blood donors

The course of cytokine and chemokine gene expression in clinically suspect arthralgia patients during progression to inflammatory arthritis

OBJECTIVES

Autoantibody responses increase years before the onset of inflammatory arthritis (IA) and are stable during transitioning from clinically suspect arthralgia (CSA) to IA. Cytokine and chemokine levels also increase years before IA onset. However, the course in the at-risk stage of CSA during progression to disease or non-progression is unknown. To increase the understanding of processes mediating disease development, we studied the course of cytokine, chemokine and related receptors gene expression in CSA patients during progression to IA and in CSA patients who ultimately did not develop IA.

METHODS

Whole-blood RNA expression of 37 inflammatory cytokines, chemokines and related receptors was determined by dual-colour reverse transcription multiplex ligation-dependent probe amplification in paired samples of CSA patients at CSA onset and either at IA development or after 24 months without IA development. ACPA-positive and ACPA-negative CSA patients developing IA were compared at CSA onset and during progression to IA. Generalised estimating equations tested changes over time. A false discovery rate approach was applied.

RESULTS

None of the cytokine/chemokine genes significantly changed in expression between CSA onset and IA development. In CSA patients without IA development, G-CSF expression decreased (P = 0.001), whereas CCR6 and TNIP1 expression increased (P < 0.001 and P = 0.002, respectively) over a 2 year period. Expression levels in ACPA-positive and ACPA-negative CSA patients who developed IA were similar.

CONCLUSION

Whole-blood gene expression of assessed cytokines, chemokines and related receptors did not change significantly from CSA to IA development. This suggests that changes in expression of these molecules may not be related to the final process of developing chronicity and may have occurred preceding CSA onset. Changes in gene expression in CSA patients without IA development may provide clues for processes related to resolution.

Exploring the causal relationship between inflammatory cytokines and inflammatory arthritis: A Mendelian randomization study

OBJECTIVES

Previous studies have reported an association between inflammatory cytokines and inflammatory arthritis, including Ankylosing spondylitis (AS), rheumatoid arthritis (RA), and psoriatic arthritis (PsA). This study aims to explore the causal relationship between inflammatory cytokines and AS, RA, and PsA using Mendelian randomization (MR).

METHODS

We conducted a bidirectional two-sample MR analysis using genetic summary data from a publicly available genome-wide association study (GWAS) that included 41 genetic variations of inflammatory cytokines, as well as genetic variant data for AS, RA, and PsA from the FinnGen consortium. The main analysis method used was Inverse variance weighted (IVW) to investigate the causal relationship between exposure and outcome. Additionally, other methods such as MR Egger, weighted median (WM), simple mode, and weighted mode were employed to strengthen the final results. Sensitivity analysis was also performed to ensure the reliability of the findings.

RESULTS

The results showed that macrophage colony-stimulating factor (MCSF) was associated with an increased risk of AS (OR = 1.163, 95 % CI = 1.016-1.33, p = 0.028). Conversely, high levels of TRAIL and beta nerve growth factor (β-NGF) were associated with a decreased risk of AS (OR = 0.892, 95 % CI = 0.81-0.982, p = 0.002; OR = 0.829, 95 % CI = 0.696-0.988, p = 0.036). Four inflammatory cytokines were found to be associated with an increased risk of PsA: vascular endothelial growth factor (VEGF) (OR = 1.161, 95 % CI = 1.057-1.275, p = 0.002); Interleukin 12p70 (IL12p70) (OR = 1.189, 95 % CI = 1.049-1.346, p = 0.007); IL10 (OR = 1.216, 95 % CI = 1.024-1.444, p = 0.026); IL13 (OR = 1.159, 95 % CI = 1.05-1.28, p = 0.004). Interleukin 1 receptor antagonist (IL-1rα) was associated with an increased risk of seropositive RA (OR = 1.181, 95 % CI = 1.044-1.336, p = 0.008). Similarly, genetic susceptibility to inflammatory arthritis was found to be causally associated with multiple inflammatory cytokines. Lastly, the sensitivity analysis supported the robustness of these findings.

CONCLUSIONS

This study provides additional insights into the relationship between inflammatory cytokines and inflammatory arthritis, and may offer new clues for the etiology, diagnosis, and treatment of inflammatory arthritis.

Comprehensive multi-omics analysis reveals the core role of glycerophospholipid metabolism in rheumatoid arthritis development

OBJECTIVES

Rheumatoid arthritis (RA) is a chronic autoimmune disease with complex causes and recurrent attacks that can easily develop into chronic arthritis and eventually lead to joint deformity. Our study aims to elucidate potential mechanism among control, new-onset RA (NORA) and chronic RA (CRA) with multi-omics analysis.

METHODS

A total of 113 RA patients and 75 controls were included in our study. Plasma and stool samples were obtained for 16S rRNA sequencing, internally transcribed spacer (ITS) sequencing and metabolomics analysis. And PBMCs were obtained for RNA sequencing. We used three models, logistic regression, least absolute shrinkage and selection operator (LASSO), and random forest, respectively, to distinguish NORA from CRA, and finally we validated model performance using an external cohort of 26 subjects.

RESULTS

Our results demonstrated intestinal flora disturbance in RA development, with significantly increased abundance of Escherichia-Shigella and Proteobacteria in NORA. We also found that the diversity was significantly reduced in CRA compared to NORA through fungi analysis. Moreover, we identified 29 differential metabolites between NORA and CRA. Pathway enrichment analysis revealed significant dysregulation of glycerophospholipid metabolism and phenylalanine metabolism pathways in RA patients. Next, we identified 40 differentially expressed genes between NORA and CRA, which acetylcholinesterase (ACHE) was the core gene and significantly enriched in glycerophospholipid metabolism pathway. Correlation analysis showed a strong negatively correlation between glycerophosphocholine and inflammatory characteristics. Additionally, we applied three approaches to develop disease classifier models that were based on plasma metabolites and gut microbiota, which effectively distinguished between new-onset and chronic RA patients in both discovery cohort and external validation cohort.

CONCLUSIONS

These findings revealed that glycerophospholipid metabolism plays a crucial role in the development and progression of RA, providing new ideas for early clinical diagnosis and optimizing treatment strategies.

Alteration of Gut Microbiota in Individuals at High-Risk for Rheumatoid Arthritis Associated With Disturbed Metabolome and the Initiation of Arthritis Through the Triggering of Mucosal Immunity Imbalance

OBJECTIVE

In this study, we aimed to decipher the gut microbiome (GM) and serum metabolic characteristic of individuals at high risk for rheumatoid arthritis (RA) and to investigate the causative effect of GM on the mucosal immune system and its involvement in the pathogenesis of arthritis.

METHODS

Fecal samples were collected from 38 healthy individuals and 53 high-risk RA individuals with anti-citrullinated protein antibody (ACPA) positivity (Pre-RA), 12 of 53 Pre-RA individuals developed RA within 5 years of follow-up. The differences in intestinal microbial composition between the healthy controls and Pre-RA individuals or among Pre-RA subgroups were identified by 16S ribosomal RNA sequencing. The serum metabolite profile and its correlation with GM were also explored. Moreover, antibiotic-pretreated mice that received GM from the healthy control or Pre-RA groups were then evaluated for intestinal permeability, inflammatory cytokines, and immune cell populations. Collagen-induced arthritis (CIA) was also applied to test the effect of fecal microbiota transplantation (FMT) from Pre-RA individuals on arthritis severity in mice.

RESULTS

Stool microbial diversity was lower in Pre-RA individuals than in healthy controls. The bacterial community structure and function significantly differed between healthy controls and Pre-RA individuals. Although there were differences to some extent in the bacterial abundance among the Pre-RA subgroups, no robust functional differences were observed. The metabolites in the serum of the Pre-RA group were dramatically different from those in the healthy controls group, with KEGG pathway enrichment of amino acid and lipid metabolism. Moreover, intestinal bacteria from the Pre-RA group increased intestinal permeability in FMT mice and zonula occludens-1 expression in the small intestine and Caco-2 cells. Moreover, Th17 cells in the mesenteric lymph nodes and Peyer's patches were also increased in mice receiving Pre-RA feces compared to healthy controls. The changes in intestinal permeability and Th17-cell activation prior to arthritis induction enhanced CIA severity in PreRA-FMT mice compared with HC-FMT mice.

CONCLUSION

Gut microbial dysbiosis and metabolome alterations already occur in individuals at high risk for RA. FMT from preclinical individuals triggers intestinal barrier dysfunction and changes mucosal immunity, further contributing to the development of arthritis.

Uncovering the Role of Epstein-Barr Virus Infection Markers for Remission in Rheumatoid Arthritis

Epstein-Barr virus (EBV) infection has been shown as a potential risk factor for the development of rheumatoid arthritis (RA). This prospective research aimed to investigate whether EBV infection markers changed during the six-month follow-up period in 133 RA patients (80 newly diagnosed on methotrexate (MTX)-RA-A, and 53 on biologic therapy-RA-B) and whether it was related to a disease outcome. Reduction of disease activity and inflammation was obtained. A significant decline in seroprevalence and titer for anti-VCA-IgM (p = 0.022 and p = 0.026) and anti-EA(D)-IgM (p = 0.022 and p = 0.006) in RA-A, and in seroprevalence and titer of anti-EA(D)-IgG in the RA-B subgroup (p = 0.021 and p = 0.006) were detected after the follow-up. A lower titer of anti-EBNA1-IgG could be considered a significant marker of RA remission in all RA patients regardless of age and gender (OR = 0.99, 95% CI OR = 0.98-0.99, p = 0.038), and also in RA-B patients separately (OR = 0.988, 95% CI OR = 0.98-0.99, p = 0.041). This study supported the basic hypothesis that the immune response to EBV infection is involved in the RA pathogenesis, at the beginning of the disease or during the RA evolution. Moreover, the potential influence of MTX or TNF-alpha inhibitors on the impairment of the host to control EBV infection was indirectly refuted.

Pathogenesis of rheumatoid arthritis and its treatment with anti-inflammatory natural products

Introduction Rheumatoid arthritis (RA) is a common autoimmune disease across the globe that is chronic and systemic as well. The disease is linked with autoantibodies and is inflammatory, eventually targeting several molecules along with certain modified self-epitopes. The disease majorly affects the joints of an individual. Rheumatoid arthritis is manifested clinically by polyarthritis linked with the dysfunction of the joints. This chiefly affects the synovial joint lining and is linked with progressive dysfunction, premature death, along with socioeconomic implications. The macrophage activation, along with the activation of certain defense cells, results in a response to self-epitopes that helps in providing a better understanding of the disease pathogenesis.  Material and methodology For this review article, papers have been retrieved and reviewed from database including PubMed, Scopus and Web of science. Relevant papers were taken fulfilling the criteria for writing this review article. Results This has resulted in the establishment of several new therapeutic techniques that serve as potential inhibitors of such cells. Researchers have gained an interest in understanding this disease to provide strategies for treatment in the last two decades. This also includes recognition followed by the treatment of the disease at its early stages. Various allopathic treatment approaches often have chronic and toxic teratogenic effects. However, to avoid this issue of toxicity followed by side effects, certain medicinal plants have been used in treating RA.  Conclusion Medicinal plants possess active phytoconstituents that entail antioxidants as well as anti-inflammatory properties, making them a helpful alternative to allopathic drugs that are often linked with highly toxic effects. This review paper entails a thorough discussion of the epidemiology, pathophysiology, diagnosis, and management of RA. The paper will also focus on the use of herbal plants in the treatment of the disease to avoid the side effects that generally occur in allopathic treatment.

Progression of pre-rheumatoid arthritis to clinical disease of joints: Potential role of mesenchymal stem cells

Rheumatoid arthritis (RA) related autoimmunity is developed at mucosal sites due to the interplay between genetic risk factors and environmental triggers. The pre-RA phase that leads to anti-citrullinated protein antibodies, rheumatoid factor, and other autoantibodies spread in the systemic circulation may not affect articular tissue for years until a mysterious second hit triggers the localization of RA-related autoimmunity in joints. Several players in the joint microenvironment mediate the synovial innate and adaptive immunological processes, eventually leading to clinical synovitis. There still exists a gap in the early phase of RA pathogenesis, i.e., the progression of diseases from the systemic circulation to joints. The lack of better understanding of these events results in the inability to answer questions about why only after a certain point of time the disease appears in joints and why in some cases, it simply remains latent and doesn't affect joints at all. In the current review, we focused on the immunomodulatory and regenerative role of mesenchymal stem cells and associated exosomes in RA pathology. We also highlighted the age-related dysregulations in activities of mesenchymal stem cells and how that might trigger homing of systemic autoimmunity to joints.

Predicting the onset of rheumatoid arthritis

Various scores have attempted to predict the onset of rheumatoid arthritis (RA). In particular, EULAR proposed a simple rule to identify new-onset arthralgia suspicious for progression to RA. However, its specificity would likely be higher if serological tests were included. In patients with clinical arthritis, reliable predictive criteria for progression to RA have also been identified. Overall, the validity of the available scores is still being debated. Such scores do not fully account for the interactions between risk factors in specific subpopulations. New technologies could help to overcome these limitations, but we need databases containing a sufficient number of RA and pre-RA patients, including pre-diagnostic monitoring. Today, the existing predictive rules cannot compete with expert opinions.

Mendelian randomization as a tool to gain insights into the mosaic causes of autoimmune diseases

Autoimmune diseases (ADs) are a broad range of disorders which are characterized by long-term inflammation and tissue damage arising from an immune response against one's own tissues. It is now widely accepted that the causes of ADs include environmental factors, genetic susceptibility and immune dysregulation. However, the exact etiology of ADs has not been fully elucidated to date. Because observational studies are plagued by confounding factors and reverse causality, no firm conclusions can be drawn about the etiology of ADs. Over the years, Mendelian randomization (MR) analysis has come into focus, offering unique perspectives and insights into the etiology of ADs and promising the discovery of potential therapeutic interventions. In MR analysis, genetic variation (alleles are randomly dispensed during meiosis, usually irrespective of environmental or lifestyle factors) is used instead of modifiable exposure to explore the link between exposure factors and disease or other outcomes. Therefore, MR analysis can provide a valuable method for exploring the causal relationship between different risk factors and ADs when its inherent assumptions and limitations are fully considered. This review summarized the recent findings of MR in major ADs, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), multiple sclerosis (MS), and type 1 diabetes mellitus (T1DM), focused on the effects of different risk factors on ADs risks. In addition, we also discussed the opportunities and challenges of MR methods in ADs research.

Genetically Determined Circulating Levels of Cytokines and the Risk of Rheumatoid Arthritis

Background: Accumulation of inflammatory leukocytes in articular tissues is the hallmark feature of rheumatoid arthritis (RA). Increasing evidence from observational studies has suggested that several cytokines may be involved in the development of RA. However, traditional observational studies are susceptible to bias from confounding and reverse causation; therefore, the potential causal relationships of individual cytokines with the risk of RA remain elusive.

Objective: In this study, we evaluated whether genetically determined circulating levels of cytokines were associated with the risk of RA by performing Mendelian randomization (MR).

Methods: We identified single nucleotide polymorphisms (SNPs) associated with circulating levels of cytokines and growth factors from a genome-wide association study (GWAS) including 8,293 participants of Finnish ancestry as instrumental variables (IVs). The association estimates of these IVs with the risk of RA were obtained from a GWAS meta-analysis including 14,361 RA cases and 43,923 controls of European ancestry. We conducted a series of MR analyses to assess the relationship between genetically determined circulating cytokines and the risk of RA, including the random-effects inverse variance-weighted, weighted-median, MR-Egger regression, and MR pleiotropy residual sum and outlier tests. For potential cytokine-RA associations supported by MR evidence, sensitivity analyses were further performed using restricted IV sets of SNPs with colocalization evidence and that excluding pleiotropic SNPs.

Results: In the primary MR analysis, there was a suggestive inverse association between genetically determined circulating level of macrophage inflammatory protein-1β (MIP-1b) and the risk of RA [odds ratio (OR): 0.95, 95% confidence interval (CI) = 0.92-0.99, p = 0.016]. The effect estimates were similar in alternative MR analyses. Among SNPs used as IVs for MIP-1b, we found 92 SNPs without documented pleiotropy and three SNPs with evidence of colocalization. The association of MIP-1b with RA from sensitivity analyses using these two sets of restricted IVs remained stable.

Conclusion: Our study suggests that genetically determined elevated circulating level of MIP-1b may be associated with a lower risk of RA. Further studies are warranted to determine how MIP-1b and related pathways may contribute to the development of RA.

Bridging Insights From Lymph Node and Synovium Studies in Early Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease of unknown etiology characterized by inflammation of the peripheral synovial joints leading to pannus formation and bone destruction. Rheumatoid Factor (RF) and anti-citrullinated protein antibodies (ACPA) are present years before clinical manifestations and are indicative of a break in tolerance that precedes chronic inflammation. The majority of studies investigating disease pathogenesis focus on the synovial joint as target site of inflammation while few studies explore the initial break in peripheral tolerance which occurs within secondary lymphoid organs such as lymph nodes. If explored during the earliest phases of RA, lymph node research may provide innovative drug targets for disease modulation or prevention. RA research largely centers on the role and origin of lymphocytes, such as pro-inflammatory T cells and macrophages that infiltrate the joint, as well as growing efforts to determine the role of stromal cells within the synovium. It is therefore important to explore these cell types also within the lymph node as a number of mouse studies suggest a prominent immunomodulatory role for lymph node stromal cells. Synovium and proximal peripheral lymph nodes should be investigated in conjunction with one another to gain understanding of the immunological processes driving RA progression from systemic autoimmunity toward synovial inflammation. This perspective seeks to provide an overview of current literature concerning the immunological changes present within lymph nodes and synovium during early RA. It will also propose areas that warrant further exploration with the aim to uncover novel targets to prevent disease progression.

Association between serum amyloid A and rheumatoid arthritis: A systematic review and meta-analysis

BACKGROUNDS

Consistent correlation of serum amyloid A (SAA) to rheumatoid arthritis (RA) is not completely established. The present study is to systematically summarize their relationship.

METHODS

Publications up to may 2021 were examined using key terms in the PubMed, Cochrane Library, Embase and China national knowledge infrastructure (CNKI) databases.

RESULTS

The total 33 studies, involving in 3524 RA cases and 3537 normal participants, were included. The pooled result indicated that the SAA level in the RA group was markedly higher than that in the control group [standardized mean difference (SMD) = 0.80, 95% CI (0.51, 1.08)]. By stratified analyses, the concentration of SAA was found to be gradually increased with the aggravation of RA. Additionally, the meta-analysis of correlation demonstrated that SAA levels were positively associated with the levels of disease activity score 28 (DAS28) [r = 0.55, 95% CI (0.15, 0.94)], erythrocyte sedimentation rate (ESR) [r = 0.65, 95% CI (0.53, 0.76)], C-reactive protein (CRP) [r = 0.92, 95% CI (0.57, 1.57)], rheumatoid factor (RF) [r = 0.24, 95% CI (0.09, 0.39)], interleukin 4 (IL-4) [r = 0.54, 95% CI (0.30, 0.78)], interleukin 6 (IL-6) [r = 0.46, 95% CI (0.27, 0.65)], interleukin 10 (IL-10) [r = 0.53, 95% CI (0.29, 0.77)], interleukin 17 (IL-17) [r = 0.52, 95% CI (0.27, 0.77)], and anti-cyclic citrullinated peptide antibody (A-CCP) [r = 0.32, 95% CI (0.15, 0.50)], but inversely linked with the levels of hemoglobin [r=-0.51, 95% CI (-0.84, -0.18)]. Furthermore, the allele of SAA 1.3 was actively related with increased risks of RA [OR=1.30, 95% CI (1.02, 1.65)] and of RA with amyloidosis [OR=2.06, 95% CI (1.63, 2.60)]. Besides, the genotype of SAA 1.3/1.3 was positively connected with the risks of RA [OR=1.56, 95% CI (1.00, 2.43)] and of RA with amyloidosis [OR=4.47, 95% CI (2.70, 7.41)].

CONCLUSIONS

High levels of SAA might be associated with elevated risk of RA, and the concentration of SAA might be gradually increased with the aggravation of RA. Moreover, high levels of SAA might play a vital role in RA by enhancing the levels of DAS28, ESR, CRP, RF, IL-4, IL-6, IL-10, IL-17 and A-CCP, or by attenuating hemoglobin levels. More importantly, the allele of SAA 1.3 and genotype of SAA 1.3/1.3 might be the risk factor of RA and of RA with amyloidosis.

Association of Parvovirus B19 with Rheumatic Diseases

Human parvovirus B19 infections are well reported to be associated with different autoimmune disorders. They can either mimic or trigger autoimmune diseases, such as systemic lupus erythematous (SLE), rheumatoid arthritis (RA), and vasculitis. A lack of awareness about this infection can result in delays in diagnosis and poor care. In this review, the basic biology and clinical aspects of the parvovirus, human immune response, and the pathogenesis in the rheumatic diseases are discussed.

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.

Neoepitopes in Type 1 Diabetes: Etiological Insights, Biomarkers and Therapeutic Targets

The mechanisms underlying type 1 diabetes (T1D) pathogenesis remain largely unknown. While autoantibodies to pancreatic beta-cell antigens are often the first biological response and thereby a useful biomarker for identifying individuals in early stages of T1D, their role in T1D pathogenesis is not well understood. Recognition of these antigenic targets by autoreactive T-cells plays a pathological role in T1D development. Recently, several beta-cell neoantigens have been described, indicating that both neoantigens and known T1D antigens escape central or peripheral tolerance. Several questions regarding the mechanisms by which tolerance is broken in T1D remain unanswered. Further delineating the timing and nature of antigenic responses could allow their use as biomarkers to improve staging, as targets for therapeutic intervention, and lead to a better understanding of the mechanisms leading to loss of tolerance. Multiple factors that contribute to cellular stress may result in the generation of beta-cell derived neoepitopes and contribute to autoimmunity. Understanding the cellular mechanisms that induce beta-cells to produce neoantigens has direct implications on development of therapies to intercept T1D disease progression. In this perspective, we will discuss evidence for the role of neoantigens in the pathogenesis of T1D, including antigenic responses and cellular mechanisms. We will additionally discuss the pathways leading to neoepitope formation and the cross talk between the immune system and the beta-cells in this regard. Ultimately, delineating the timing of neoepitope generation in T1D pathogenesis will determine their role as biomarkers as well as therapeutic targets.

Antibodies to Citrullinated Proteins (ACPA) Associate with Markers of Osteoclast Activation and Bone Destruction in the Bone Marrow of Patients with Rheumatoid Arthritis

Normalizing bone metabolism is a challenge in rheumatoid arthritis (RA). Studies in mice suggest that anti-citrullinated protein antibodies (ACPAs) can trigger osteoclast activation and bone resorption in the bone marrow. However, data on the presence and role of ACPAs in human bone marrow are scarce. We investigated whether ACPAs can contribute to osteoclast activation and bone erosion in RA bone marrow. Anti-cyclic citrullinated peptide antibodies (anti-CCP Abs), osteoclast activation indicators–the tartrate-resistant acid phosphatase 5b (TRAP5b) and cathepsin K, and bone degradation marker–C-terminal telopeptide of type I collagen (CTX-I) were measured in the bone marrow and peripheral blood of RA patients using ELISAs. We found that ACPAs present in RA bone marrow was associated with increased amounts of TRAP5b, cathepsin K and CTX-I in this location. Levels of IL-8, the key mediator of anti-citrullinated protein antibody (ACPA)-induced bone resorption, were also elevated in bone marrow containing anti-CCP Abs and positively correlated with TRAP5b and cathepsin K concentrations. Higher levels of TRAP5b, cathepsin K, CTX-I and IL-8 in bone marrow compared to peripheral blood indicate local generation of these molecules. Our results complement data from animal studies and highlight the relevance of ACPAs and bone marrow in bone resorption in RA.

Altered Antibody Response to Epstein-Barr Virus in Patients With Rheumatoid Arthritis and Healthy Subjects Predisposed to the Disease. A Twin Study

Objectives: To study Epstein-Barr virus (EBV) antibody patterns in twin individuals with rheumatoid arthritis (RA) and their healthy co-twins, and to determine the heritability of antibody responses against the EBV encoded EBNA1 protein.

Methods: Isotypes of EBNA1 antibodies were measured in 137 RA affected- and 150 healthy twin pairs. We estimated the effect of RA and RA predisposition, anti-citrullinated antibodies (ACPA), IgM rheumatoid factor (RF), the shared epitope (SE) and the PTPN22-T allele (PTPN22) on the level of EBNA1 antibodies. We also determined the heritability of EBNA1 antibody levels.

Results: IgA-EBNA1 antibody levels were increased in twins from RA discordant twin pairs irrespective of RA, ACPA or IgM-RF status. The IgG-EBNA1 antibody level was elevated in healthy co-twins from RA discordant twin pairs but not in RA affected twins. The IgM-EBNA1 antibody level was elevated in both RA twins and their healthy co-twins. The effect of RA on the IgA-EBNA1 antibody level was reversed when SE was present and with no effect of PTPN22. The heritability of IgA-, IgG- and IgM-EBNA1 antibody level was 40.6, 65.5, and 54.3%, with no effect of environment shared by the twins.

Conclusion: EBNA1 antibody levels are distinctively different between patients with RA and healthy subjects but also between relatives of RA strongly predisposed to RA and healthy subjects. The high level of IgA EBNA1 antibodies associated with RA and a family predisposition to RA is attributable to both genetics incl. the shared epitope and environmental variation.

Serum miRNA Signature in Rheumatoid Arthritis and "At-Risk Individuals"

Background

MicroRNAs (miRNAs) are small non-coding RNAs which have been implicated as potential biomarkers or therapeutic targets in autoimmune diseases. This study examines circulatory miRNAs in RA patients and further investigates if a serum miRNA signature precedes clinical manifestations of disease in arthralgia or “at-risk individuals”.

Methods

Serum was collected from HC subjects (N = 20), RA patients (N = 50), and arthralgia subjects (N = 10), in addition to a subgroup of the RA patients post-methotrexate (MTX) (N = 18). The FirePlex miRNA Immunology-V2 panel was selected for multiplex analysis of 68 miRNAs in each sample. DNA intelligent analysis (DIANA)-mirPath and Ingenuity Pathway Analysis (IPA) software were used to predict pathways targeted by the dysregulated miRNAs.

Results

8 miRNA (miR-126-3p, let-7d-5p, miR-431-3p, miR-221-3p, miR-24-3p, miR-130a-3p, miR-339-5p, let-7i-5p) were significantly elevated in RA serum compared to HC (all p < 0.01) and 1 miRNA (miR-17-5p) was significantly lower in RA (p < 0.01). High specificity and sensitivity were determined by receiver operating characteristic (ROC) curve analysis. Both miR-339-5p and let-7i-5p were significantly reduced post-MTX (both p < 0.01). MiR-126-3p, let-7d-5p, miR-431-3p, miR-221-3p, miR-24-3p, miR-130a-3p were also significantly elevated in subjects “at risk” of developing RA (all p < 0.05) compared to HC. IPA analysis of this miRNA signature identified downstream targets including key transcription factors NF-κB, STAT-1, STAT-3, cytokines IL-1β, TNF-α, and matrix-metalloproteases all importantly associated with RA pathogenesis.

Conclusion

This study identified six miRNAs that are altered in both RA and “at-risk individuals,” which potentially regulate key downstream pathways involved in regulating inflammation. These may have potential as predictive signature for disease onset and early progression.

Association of Lipid Mediators With Development of Future Incident Inflammatory Arthritis in an Anti-Citrullinated Protein Antibody-Positive Population

OBJECTIVE

To determine the association of polyunsaturated fatty acid (PUFA)-derived lipid mediators with progression from rheumatoid arthritis (RA)-related autoimmunity to inflammatory arthritis (IA).

METHODS

We conducted a prospective cohort study using data from the Studies of the Etiology of Rheumatoid Arthritis (SERA). SERA enrolled first-degree relatives (FDRs) of individuals with RA (FDR cohort) and individuals who screened positive for RA-related autoantibodies at health fairs (screened cohort). We followed up 133 anti-cyclic citrullinated peptide 3.1 (anti-CCP3.1)-positive participants, 29 of whom developed IA. Lipid mediators selected a priori were quantified from stored plasma samples using liquid chromatography tandem mass spectrometry. We fit multivariable Cox proportional hazards models for each lipid mediator as a time-varying variable. For lipid mediators found to be significantly associated with IA, we then examined interleukin-1β (IL-1β), IL-6, IL-8, and tumor necrosis factor (TNF) as potential statistical mediators.

RESULTS

For every 1 natural log pg/ml increase in the circulating plasma levels of proinflammatory 5-HETE, the risk of developing IA increased by 241% (hazard ratio 2.41 [95% confidence interval 1.43-4.07]) after adjusting for age at baseline, cohort (FDR or screened), and shared epitope status. The models examining 15-HETE and 17-HDHA had the same trend but did not reach significance. We did not find evidence that the association between 5-HETE and IA risk was influenced by the proinflammatory cytokines tested.

CONCLUSION

In a prospective cohort of anti-CCP-positive individuals, higher levels of 5-HETE, an important precursor to proinflammatory leukotrienes, is associated with subsequent IA. Our findings highlight the potential significance of these PUFA metabolites in pre-RA populations.

Early diagnosis and treatment for Sjögren's syndrome: current challenges, redefined disease stages and future prospects

There are some challenges and unmet needs in the early diagnosis and management of Sjögren's syndrome (SjS) such as prominent glandular dysfunction at diagnosis and long diagnostic delay. Those challenges are partly attributed to the lack of a good knowledge of the early stages of SjS, which is a major obstacle to delivering appropriate care to SjS patients. Findings from both clinical and experimental studies suggest the plausibility of a redefined SjS course consisting of 4 stages, which includes initiation stage, preclinical stage, asymptomatic SjS stage and overt SjS stage. More studies focusing on the pathological processes and changes during the early stages of SjS are needed. To enable early diagnosis and treatment for SjS, more useful biomarkers of the early stages of SjS need to be identified, and individuals at high risk of SjS development need to be identified. Appropriate screening can be performed to facilitate the early diagnosis of SjS among those high-risk individuals.

Autoantibodies are major predictors of arthritis development in patients with anti-citrullinated protein antibodies and musculoskeletal pain

Objectives: Predictors of arthritis development are highly warranted among patients with anti-citrullinated protein antibodies (ACPAs) and musculoskeletal symptoms to optimize clinical management. We aimed to identify clinical and laboratory predictors of arthritis development, including biochemically assessed alcohol consumption, among ACPA-positive patients with musculoskeletal pain.Method: 82 ACPA-positive individuals with musculoskeletal pain but no clinical arthritis were followed for a median of 72 months (interquartile range 57-81 months). We evaluated the prognostic value of baseline clinical and laboratory factors including smoking, symptom duration, age, gender, shared epitope, rheumatoid factor (RF), anti-carbamylated protein antibodies, ACPA levels, erythrocyte sedimentation rate, C-reactive protein levels, tender joint count, patient-reported general well-being, 28-joint Disease Activity Score, and alcohol consumption as measured by phosphatidyl ethanol (PEth) levels in whole blood.Results: During follow-up, 48% developed at least one arthritis. Multivariable analysis revealed an increased risk of arthritis development with RF positivity [hazard ratio (HR) = 2.3, 95% confidence interval (CI) 1.1-4.8, p = 0.028] and higher ACPA levels (HR = 1.0, 95% CI 1.000-1.001, p = 0.002). High levels of RF (HR = 4.4, 95% CI 1.7-11) entailed the highest HR in this ACPA-positive population. Neither clinical characteristics nor alcohol consumption measured by PEth conferred significant prognostic value.Conclusions: ACPA levels and concurrent presence of RF are independent predictors of arthritis development among ACPA-positive patients with musculoskeletal pain. The results are compatible with a dose-response relationship between RA-related autoantibodies and risk of arthritis development.

Anti-carbamylated protein and peptide antibodies as potential inflammatory joint biomarkers in the relatives of rheumatoid arthritis patients

OBJECTIVE

Antibodies against carbamylated proteins/peptide (CarP) have been associated with severity in rheumatoid arthritis (RA) patients. However, their role in risk groups, specific targets and relation with periodontal disease (PD) is uncertain yet. The aim of this study was evaluated the association between the levels of anti-CarP with clinical manifestation, human leukocyte antigen (HLA) alleles, periodontal activity markers, PD diagnosis, PD severity, and presence of Porphyromonas gingivalis (P gingivalis) in relatives of patients with RA.

METHODS

One hundred and twenty-four individuals with a family history of RA in first-degree relatives (FDR) and 124 healthy individuals gender- and age-matched, RA activity was assessed. Antibodies against carbamylated protein anti-FCS-Carp and 2 carbamylated peptides of fibrinogen were selected (anti-Ca-Fib2, anti-Ca-Fib3).

RESULTS

Anti-FCS-Carp-positive, anti-Ca-Fib2 and anti-Ca-Fib3 were more frequent in FDR than controls (25.0% vs 14.5%, 34.7% vs 15.3% and 33.1% vs 11.3%, respectively). Anti-FCS-CarP were associated with the HLA-DRB1-SE* 1402 allele (P = .035) and highly sensitive C-reactive protein levels (P = .016), the anti-Ca-Fib2 antibodies were associated with the HLA-DRB1-SE* 1501 allele (P = .03), with non-SE* 0901 allele (P = .01), the anti-Ca-Fib3 was associated with positive rheumatoid factor (P = .0012). The FDR condition was associated with the presence of anti-Ca-Fib3 (odds ratio [OR] =4.7; 95% CI = 1.8-11.7; P = .001) and painful joints (OR = 2.2; 95% CI = 1.01-4.68; P = .045); we also detected an important trend toward the presence of P gingivalis (OR = 1.9; 95% CI = 0.9-3.7; P = .062).

CONCLUSION

The presence of anti-FCS-Carp, anti-Ca-Fib3 and anti-Ca-Fib2 antibodies may have a role for these antibodies as early biomarkers in the development of RA, probably including additional mechanisms related with other non-SE alleles; the anti-peptide antibodies proposed in the present study may represent a simpler way to identify antibodies directed to a specific target.

Role of Viral Infections in the Pathogenesis of Sjögren's Syndrome: Different Characteristics of Epstein-Barr Virus and HTLV-1

Viruses are possible pathogenic agents in several autoimmune diseases. Sjögren’s syndrome (SS), which involves exocrine dysfunction and the appearance of autoantibodies, shows salivary gland- and lacrimal gland-oriented clinical features. Epstein-Barr virus (EBV) is the most investigated pathogen as a candidate that directly induces the phenotype found in SS. The reactivation of the virus with various stimuli induced a dysregulated form of EBV that has the potential to infect SS-specific B cells and plasma cells that are closely associated with the function of an ectopic lymphoid structure that contains a germinal center (GC) in the salivary glands of individuals with SS. The involvement of human T-cell leukemia virus type 1 (HTLV-1) in SS has been epidemiologically established, but the disease concept of HTLV-1-associated SS remains unexplained due to limited evidence from basic research. Unlike the cell-to-cell contact between lymphocytes, biofilm-like structures are candidates as the mode of HTLV-1 infection of salivary gland epithelial cells (SGECs). HTLV-1 can infect SGECs with enhanced levels of inflammatory cytokines and chemokines that are secreted from SGECs. Regardless of the different targets that viruses have with respect to affinitive lymphocytes, viruses are involved in the formation of pathological alterations with immunological modifications in SS.

Measuring ACPA in the general population or primary care: is it useful?

Rheumatoid arthritis (RA) is associated with a significant disease burden and high costs for society. Because the disease has identifiable preclinical stages, screening and prevention have become a possibility in RA. Anticitrullinated peptide antibodies (ACPAs) are arguably the most likely candidate biomarker to screen for RA. This paper reviews the evidence for the use of ACPAs as a screening test in the broader general population, to identify individuals at high risk of subsequent onset of RA. We will review the diagnostic properties of the test and its positive and negative predictive value in different settings. We will discuss how ACPA testing could effectively be integrated in a broader screening strategy for RA.

Oral Microbiota Perturbations Are Linked to High Risk for Rheumatoid Arthritis

Oral microbial dysbiosis is known to increase susceptibility of an individual to develop rheumatoid arthritis (RA). Individuals at-risk of RA may undergo different phases of disease progression. In this study, we aim to investigate whether and whereby the oral microbiome communities alter prior to symptoms of RA. Seventy-nine saliva samples were collected from 29 high-risk individuals, who were positive for anti-citrullinated protein antibodies (ACPA) and have no clinical arthritis, 27 RA patients and 23 healthy controls (HCs). The salivary microbiome was examined using 16S ribosomal RNA gene sequencing. Alpha and beta diversity analysis and the linear discriminant analysis were applied to examine the bacterial diversity, community structure and discriminatory taxa between three groups, respectively. The correlation between salivary bacteria and autoantibodies were analyzed. In the “pre-clinical” stages, salivary microbial diversity was significantly reduced comparing to RA patients and HCs. In contrast to HCs, like RA patients, individuals at high-risk for RA showed a reduction in the abundance of genus Defluviitaleaceae_UCG-011 and the species Neisseria oralis, but an expansion of Prevotella_6. Unexpectedly, the relative abundance of Porphyromonas gingivalis, reported as opportunistic pathogens for RA development, was significantly decreased in high-risk individuals. Additionally, we identified four genera in the saliva from high-risk individuals positively correlated with serum ACPA titers, and the other two genera inversely displayed. In summary, we observed a characteristic compositional change of salivary microbes in individuals at high-risk for RA, suggesting that oral microbiota dysbiosis occurs in the “pre-clinical” stage of RA and are correlated with systemic autoimmune features.

Detection of PLA2R Autoantibodies before the Diagnosis of Membranous Nephropathy

BACKGROUND

Circulating serum autoantibodies against the M-type phospholipase A2 receptor (PLA2R-AB) are a key biomarker in the diagnosis and monitoring of primary membranous nephropathy (MN). However, little is known about the appearance and trajectory of PLA2R-AB before the clinical diagnosis of MN.

METHODS

Using the Department of Defense Serum Repository, we analyzed PLA2R-AB in multiple, 1054 longitudinal serum samples collected before diagnosis of MN from 134 individuals with primary MN, 35 individuals with secondary MN, and 134 healthy volunteers. We evaluated the presence and timing of non-nephrotic range proteinuria (NNRP) and serum albumin measurements in relation to PLA2R-AB status.

RESULTS

Analysis of PLA2R-AB in longitudinal serum samples revealed seropositivity in 44% (59 out of 134) of primary MN cases, 3% (one out of 35) of secondary MN cases, and in 0% of healthy controls. Among patients with MN, PLA2R-AB were detectable at a median of 274 days before renal biopsy diagnosis (interquartile range, 71-821 days). Approximately one third of the participants became seropositive within 3 months of MN diagnosis. Of the 21 individuals with documented prediagnostic NNRP, 43% (nine out of 21) were seropositive before NNRP was first documented and 28.5% (six out of 21) were seropositive at the same time as NNRP; 66% (39 out of 59) of those seropositive for PLA2R-AB had hypoalbuminemia present at the time antibody was initially detected. Twelve participants (20%) were seropositive before hypoalbuminemia became apparent, and eight participants (14%) were seropositive after hypoalbuminemia became apparent.

CONCLUSIONS

Circulating PLA2R-AB are detectable months to years before documented NNRP and biopsy-proven diagnosis in patients with MN.

Shared and unique immune alterations in pre-clinical autoimmunity

Progression from health to a classified autoimmune disease is an evolving process that can happen rapidly in some diseases, but usually takes years to develop. Specific immune alterations predate pathogenic autoimmunity and can be used as disease biomarkers to identify high-risk individuals for prevention studies applied in the pre-clinical state. Here we discuss recent findings that illuminate specific immune pathways that are altered in the earliest phases of pre-clinical autoimmunity as well as those mediators more closely associated with later clinically apparent and classified disease onset.

Citrullination facilitates cross-reactivity of rheumatoid factor with non-IgG1 Fc epitopes in rheumatoid arthritis

Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPAs) are the two most prevalent autoantibodies in rheumatoid arthritis (RA), and are thought to have distinct autoantigen targets. Whilst RF targets the Fc region of antibodies, ACPAs target a far broader spectrum of citrullinated peptides. Here we demonstrate significant sequence and structural homology between proposed RF target epitopes in IgG1 Fc and the ACPA target fibrinogen. Two of the three homologous sequences were susceptible to citrullination, and this modification, which occurs extensively in RA, permitted significant cross-reactivity of RF+ patient sera with fibrinogen in both western blots and ELISAs. Crucially, this reactivity was specific to RF as it was absent in RF− patient and healthy control sera, and could be inhibited by pre-incubation with IgG1 Fc. These studies establish fibrinogen as a common target for both RF and ACPAs, and suggest a new mechanism in RF-mediated autoimmune diseases wherein RF may act as a precursor from which the ACPA response evolves.

Lifetime Pesticide Use and Antinuclear Antibodies in Male Farmers From the Agricultural Health Study

Farming and pesticide use have been associated with systemic autoimmune diseases, and while certain organochlorine insecticides and other pesticides are suspected to influence risk, the role of specific pesticides in the development of systemic autoimmunity is not known. We measured serum antinuclear autoantibodies (ANA) by immunofluorescence on Hep-2 cells in 668 male farmers in the study of Biomarkers of Exposure and Effect in Agriculture (BEEA; 2010-2013), an Agricultural Health Study (AHS) subcohort. We examined ANA in relation to lifetime use of 46 pesticides first reported at AHS enrollment (1993-1997) and updated at intervals through BEEA enrollment. Odds ratios (OR) and 95% confidence intervals (CI) were estimated after adjusting for age, state, education, season of blood draw, current pesticide use, and correlated pesticides. Having ANA antibodies (3 or 4+ intensity at a 1:80 dilution, 21% of study participants) was associated with a reported history of seeking medical care due to exposure to pesticides (OR 2.15; 95%CI 1.17, 3.95), use of the fumigant methyl bromide (OR 3.16; 95%CI 1.05, 9.5), and use of petroleum oil/distillates (OR 1.50; 95%CI 1.00, 2.25). Using a higher threshold (3 or 4+ at a 1:160 dilution, 9%) ANA positivity was associated with the carbamate insecticide aldicarb (OR 4.82; 95%CI 1.33, 17.5) and greater combined use of four cyclodiene organochlorine insecticides (top tertile of intensity-weighted lifetime days vs. no use; OR T3 3.20; 95%CI 1.10, 9.27). By contrast, greater use of non-cyclodiene organochlorine insecticides was inversely associated with ANA (1:80 dilution 3 or 4+, OR T3 0.24; 95%CI 0.08, 0.72). Specific autoantibodies (to extractable nuclear antigens and anti-dsDNA), measured on those with ANA detected at the 1:80 dilution 3 or 4+, were seen in 15 individuals (2%), and were associated with use of two or more cyclodiene organochlorine insecticides and several other pesticides (e.g., carbofuran, ethylene dibromide). These findings suggest that specific pesticide exposures may have long-term effects on ANA prevalence and support the hypothesis that certain organochlorine insecticides may increase the risk of developing systemic autoimmunity.

EBNA1 IgM-Based Discrimination Between Rheumatoid Arthritis Patients, Systemic Lupus Erythematosus Patients and Healthy Controls

Epstein-Barr Virus (EBV) has been associated with development of rheumatic connective tissue diseases like rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) in genetically susceptible individuals. Diagnosis of RA and SLE relies on clinical criteria in combination with the presence of characteristic autoantibodies. In addition, antibodies to several EBV antigens have been shown to be elevated in patients with these diseases compared to healthy controls (HC). Here, we elaborated improved enzyme-linked immunosorbent assays for antibodies (IgM, IgA, IgG) to the EBV proteins Epstein-Barr Virus nuclear antigen (EBNA)1 and early antigen diffuse (EAD) in order to determine their potential diagnostic role. We showed that especially EBNA1 IgM distinguished RA from SLE and HCs and also distinguished SLE from HCs. EBNA1 IgA was almost as effective in differentiating RA from SLE and HC, while EAD IgG and IgA were able to discern SLE patients from RA patients and HCs. Collectively, these findings illustrate the potential diagnostic use of antibodies to EBV proteins to diagnose RA and to differentiate SLE from RA.

Transcriptional signature associated with early rheumatoid arthritis and healthy individuals at high risk to develop the disease

Background

Little is known regarding the mechanisms underlying the loss of tolerance in the early and preclinical stages of autoimmune diseases. The aim of this work was to identify the transcriptional profile and signaling pathways associated to non-treated early rheumatoid arthritis (RA) and subjects at high risk. Several biomarker candidates for early RA are proposed.

Methods

Whole blood total RNA was obtained from non-treated early RA patients with <1 year of evolution as well as from healthy first-degree relatives of patients with RA (FDR) classified as ACCP+ and ACCP- according to their antibodies serum levels against cyclic citrullinated peptides. Complementary RNA (cRNA) was synthetized and hybridized to high-density microarrays. Data was analyzed in Genespring Software and functional categories were assigned to a specific transcriptome identified in subjects with RA and FDR ACCP positive. Specific signaling pathways for genes associated to RA were identified. Gene expression was evaluated by qPCR. Receiver operating characteristic (ROC) analysis was used to evaluate these genes as biomarkers.

Results

A characteristic transcriptome of 551 induced genes and 4,402 repressed genes were identified in early RA patients. Bioinformatics analysis of the data identified a specific transcriptome in RA patients. Moreover, some overlapped transcriptional profiles between patients with RA and ACCP+ were identified, suggesting an up-regulated distinctive transcriptome from the preclinical stages up to progression to an early RA state. A total of 203 pathways have up-regulated genes that are shared between RA and ACCP+. Some of these genes show potential to be used as progression biomarkers for early RA with area under the curve of ROC > 0.92. These genes come from several functional categories associated to inflammation, Wnt signaling and type I interferon pathways.

Conclusion

The presence of a specific transcriptome in whole blood of RA patients suggests the activation of a specific inflammatory transcriptional signature in early RA development. The set of overexpressed genes in early RA patients that are shared with ACCP+ subjects but not with ACCP- subjects, can represent a transcriptional signature involved with the transition of a preclinical to a clinical RA stage. Some of these particular up-regulated and down-regulated genes are related to inflammatory processes and could be considered as biomarker candidates for disease progression in subjects at risk to develop RA.

The role of anti-citrullinated protein antibodies (ACPA) in the pathogenesis of rheumatoid arthritis

The most specific autoimmunity known for rheumatoid arthritis (RA) is reflected by generation of anti-citrullinated protein antibodies (ACPA). Presence of ACPA in established RA is associated with disease severity, while generation of ACPA at early developmental phases of RA can have a strong predictive value for progressing to the full-blown disease. Hence, development of ACPA may be of crucial importance to the pathogenesis of RA. Therefore, a lot of effort has been put recently to investigate the feature of ACPA at early developmental stages of RA (before disease onset) and functional activities of these autoantibodies. Results of these studies enlarged the knowledge about the nature of ACPA, which is essential for planning the therapeutic or preventive strategies interfering with their development and pathogenic functions. In this review we describe recent evidence for a role of ACPA in the etiopathogenesis of RA and indicate key unresolved issues regarding ACPA biology that need to be clarified in the future.

Preventive Treatments for Rheumatoid Arthritis: Issues Regarding Patient Preferences

The detection of biomarkers in the preclinical phase of rheumatoid arthritis (RA) and recent therapeutic advances suggest that it may be possible to identify and treat persons at high risk and to prevent the development of RA. Several trials are ongoing to test the efficacy of a therapeutic intervention in primary prevention. This paper reviews potential populations that might be considered for preventative medication. Further, we review the medications that are being explored to treat individuals considered at high risk of developing RA. Finally, in a group of asymptomatic individuals at high risk of developing RA, we assessed which factors mattered most when considering a preventive therapeutic intervention and what type of preventive treatment would be most acceptable to them. Understanding subjects' perceptions of risks and benefits and willingness to undergo preventive therapy will be important in designing and implementing screening and preventive strategies.

The role of female hormonal factors in the development of rheumatoid arthritis

RA is the most common chronic systemic autoimmune disease, with a higher prevalence in women, suggesting female hormonal factors play a role in the development of the disease. However, many controversies still exist. The aim of this review was to appraise data from recent research concerning female hormonal factors and their association with RA disease development. The study of female hormonal factors is challenging because serum levels may differ throughout a woman's lifetime and interact with various environmental, immunological, genetic and endocrine factors influencing the development of autoimmunity. As some female hormonal factors may be potentially modifiable, understanding their impact on RA development is clinically relevant and may result in specific preventive interventions in high-risk populations.

Value of Biomarkers in the Prevention of Rheumatoid Arthritis

Recent diagnostic advances allow to identify persons in a pre-symptomatic stage of rheumatoid arthritis (RA), opening the way for a preventive therapeutic intervention, which may potentially be curative. We review and discuss existing biomarkers predictive of future onset of RA. A responsible use of biomarkers in clinical settings will require an integration of blood-based tests, imaging techniques, clinical history, environmental risk factors, and family history.

Presence of anticitrullinated protein antibodies in a large population-based cohort from the Netherlands

OBJECTIVES

To determine the prevalence of anticitrullinated protein antibodies (ACPAs) and their association with known rheumatoid arthritis (RA) risk factors in the general population.

METHODS

Lifelines is a multidisciplinary prospective population-based cohort study in the Netherlands. Cross-sectional data from 40 136 participants were used. The detection of ACPA was performed by measuring anti-CCP2 on the Phadia-250 analyser with levels ≥6.2 U/mL considered positive. An extensive questionnaire was taken on demographic and clinical information, including smoking, periodontal health and early symptoms of musculoskeletal disorders. RA was defined by a combination of self-reported RA, medication use for the indication of rheumatism and visiting a medical specialist within the last year.

RESULTS

Of the total 40 136 unselected individuals, 401 (1.0%) had ACPA level ≥6.2 U/mL. ACPA positivity was significantly associated with older age, female gender, smoking, joint complaints, RA and first degree relatives with rheumatism. Of the ACPA-positive participants, 22.4% had RA (15.2% had defined RA according to our criteria and 7.2% self-reported RA only). In participants without RA, 311 (0.8%) were ACPA-positive. In the non-RA group, older age, smoking and joint complaints remained significantly more frequently present in ACPA-positive compared with ACPA-negative participants.

CONCLUSIONS

In this large population-based study, the prevalence of ACPA levels ≥6.2 U/mL was 1.0% for the total group and 0.8% when excluding patients with RA. Older age, smoking and joint complaints were more frequently present in ACPA-positive Lifelines participants. To our knowledge, this study is the largest study to date on ACPA positivity in the general, mostly Caucasian population.

Analysis of serum immune markers in seropositive and seronegative rheumatoid arthritis and in high-risk seropositive arthralgia patients

Presence of autoantibodies precedes development of seropositive rheumatoid arthritis (SP RA) and seropositive arthralgia patients (SAP) are at risk of developing RA. The aims of the study are to identify additional serum immune markers discriminating between SP and seronegative (SN) RA, and markers identifying high-risk SAP. Sera from SAP (n = 27), SP RA (n = 22), SN RA (n = 11) and healthy controls (n = 20) were analyzed using the Human Cytokine 25-Plex Panel. Selected markers were validated in independent cohorts of SP RA (n = 35) and SN RA (n = 12) patients. Eleven of 27 SAP developed RA within 8 months (median follow-up time, range 1-32 months), and their baseline serum markers were compared to 16 non-progressing SAP. SAP and SP RA patients showed a marked overlap in their systemic immune profiles, while SN RA showed a distinct immune profile. Three of 4 markers discriminating between SP and SN RA (IL-1β, IL-15 and Eotaxin, but not CCL5) were similarly modulated in independent cohorts. SAP progressing to RA showed trends for increases in IL-5, MIP-1β, IL-1RA and IL-12 compared to non-progressing SAP. ROC analysis showed that serum IL-5 most accurately discriminated between the two SAP groups (AUC > 0.8), suggesting that baseline IL-5 levels may aid the identification of high-risk SAP.

How well do ACPA discriminate and predict RA in the general population: a study based on 12 590 population-representative Swedish twins

Objective

Anti-citrullinated protein antibodies (ACPA) are highly specific for rheumatoid arthritis (RA), but the diagnostic accuracy of ACPA in the general population has not been thoroughly assessed. We aimed to assess the diagnostic accuracy of ACPA for RA in the general population and to further characterise the citrullinated peptide recognition pattern.

Methods

Serum samples from a large population-representative twin cohort consisting of 12 590 individuals were analysed for the presence of ACPA using anti-CCP2 ELISA. All ACPA-positive samples were further tested on ELISAs for four peptide-specific ACPA. RA cases were identified by linkage to the Swedish National Patient Register at inclusion and after a median follow-up of 37 months (IQR 31–49).

Results

350 out of 12 590 individuals had a positive anti-CCP2 test, measuring ACPA. Of these, 103 had an RA diagnosis at the time of blood donation and inclusion. During a median follow-up of 3 years, an additional 21 of the remaining 247 ACPA-positive individuals developed RA. Overall, a positive anti-CCP2 test had a positive predictive value of 29% for prevalent RA at inclusion (negative predictive value of 99.6%). High titres (>3× cut-off) of anti-CCP2 increased the positive predictive value to 48% (negative predictive value of 99.5%). ACPA-positive individuals without RA had lower anti-CCP2 titres and fewer peptide-specific ACPA than ACPA-positive patients with RA and higher C reactive protein levels than ACPA-negative individuals without RA.

Conclusion

Presence of ACPA and especially high titres of anti-CCP2 have a high diagnostic accuracy for an RA diagnosis in a population setting.

Smoking and Air Pollution as Pro-Inflammatory Triggers for the Development of Rheumatoid Arthritis

INTRODUCTION

Smoking is now well recognized not only as a risk factor for rheumatoid arthritis (RA), but also as a determinant of disease activity, severity, response to therapy, and possibly mortality.

METHODS

Studies, mostly recent, which have provided significant insights into the molecular and cellular mechanisms which underpin the pathogenesis of smoking-related RA, as well as the possible involvement of other types of outdoor and indoor pollution form the basis of this review.

RESULTS

Smoking initiates chronic inflammatory events in the lungs. These, in turn, promote the release of the enzymes, peptidylarginine deiminases 2 and 4 from smoke-activated, resident and infiltrating pulmonary phagocytes. Peptidylarginine deiminases mediate conversion of various endogenous proteins to putative citrullinated autoantigens. In genetically susceptible individuals, these autoantigens trigger the production of anti-citrullinated peptide, pathogenic autoantibodies, an event which precedes the development of RA.

CONCLUSIONS

An increasing body of evidence has linked chronic inflammatory events in the lungs of smokers, to the production of anti-citrullinated peptide autoantibodies and development of RA. Creation of awareness of the associated risks, assessment of smoking status and implementation of compelling antismoking strategies must be included in the routine clinical management of patients presenting with suspected RA.

IMPLICATIONS

Chronic inflammatory mechanisms operative in the lungs of smokers lead to the production of anti-citrullinated protein antibodies which, in turn, drive the development of RA. These mechanistic insights not only reinforce the association between smoking and risk for RA, but also the necessity to increase the level of awareness in those at highest risk.

Autoantibodies in prediction of the development of rheumatoid arthritis among healthy relatives of patients with the disease

OBJECTIVE

Although blood bank-based studies have shown that rheumatoid arthritis (RA)-related autoantibodies are present before the onset of RA, information on their positive predictive value (PPV) for development of RA in healthy individuals is scarce. This study was undertaken to assess the 5-year PPV of serum IgM rheumatoid factor (IgM-RF) and anti-cyclic citrullinated peptide (anti-CCP) for the development of RA among healthy relatives of patients with RA.

METHODS

Healthy relatives of RA patients were invited to participate in a cohort study. At baseline, information on participants' medical history was obtained, and serum levels of IgM-RF and anti-CCP antibodies were determined (by nephelometry and second-generation anti-CCP enzyme-linked immunosorbent assay, respectively). The subjects were followed up every 4 months via a structured interview (Community Oriented Program for Control of Rheumatic Diseases [COPCORD] questionnaire). When the COPCORD questionnaire indicated possible arthritis, subjects underwent an in-office rheumatology assessment including joint count. The study end point was defined as fulfillment of the American College of Rheumatology criteria for RA.

RESULTS

Eight hundred nineteen initially healthy relatives of 252 patients with RA were included (69% female, 41% offspring, mean ± SD age 35 ± 12 years). Eleven (1.3%) were positive for both anti-CCP-2 and RF, 12 (1.5%) only for anti-CCP-2, and 16 (2%) only for RF. RA developed in 17 (2.1%) of the relatives during the 5-year followup (3,313 person-years for the seronegative group and 60.8 person-years for the anti-CCP-2-positive group). The PPV was 64% when both anti-CCP-2 and RF were positive and 58% when only anti-CCP-2 was positive. Offspring of patients with RA had an independent 3-fold increased risk of developing RA.

CONCLUSION

Results of the present study indicate that the magnitude of risk for developing RA in healthy relatives of patients with RA can be estimated using simple routine laboratory tests.

Self-rated health in women prior to clinical onset of multiple sclerosis: A study within the Danish National Birth Cohort

BACKGROUND

It has been suggested that onset of multiple sclerosis (MS) is preceded by a clinically silent period of up to 10 years.

OBJECTIVES

Examine whether such a period should be associated with poor self-rated health (SRH).

METHODS

Information on SRH before pregnancy was ascertained among 80,848 women participating in the Danish National Birth Cohort (DNBC) 1996-2002. Women were followed for MS from enrolment in DNBC in the 16th week of pregnancy until 31 December 2011. Associations between SRH and MS were evaluated by means of hazard ratios (HR) with 95% confidence intervals (CIs) using Cox proportional hazard models.

RESULTS

During on average 11.7 years of follow-up, 239 women were diagnosed with MS. Overall, neither women with fair (HR = 1.09 (95% CI = 0.83-1.41), n = 113) nor poor pre-pregnancy SRH (HR = 0.94 (95% CI = 0.47-1.87), n = 9) were at an increased risk of MS compared with women reporting very good pre-pregnancy SRH. Supplementary analyses showed no significant differences in MS risk in consecutive periods of follow-up.

CONCLUSION

In this first prospective cohort study assessing MS risk as a function of SRH, we found no indication of a long period of poor SRH prior to MS. Our findings based on pregnant women may not necessarily apply to all women.

T cell subsets: an immunological biomarker to predict progression to clinical arthritis in ACPA-positive individuals

Objectives

Anticitrullinated protein antibody (ACPA)+ individuals with non-specific musculoskeletal symptoms are at risk of inflammatory arthritis (IA). This study aims to demonstrate the predictive value of T cell subset quantification for progression towards IA and compare it with previously identified clinical predictors of progression.

Methods

103 ACPA+ individuals without clinical synovitis were observed 3-monthly for 12 months and then as clinically indicated. The end point was the development of IA. Naïve, regulatory T cells (Treg) and inflammation related cells (IRCs) were quantified by flow cytometry. Areas under the ROC curve (AUC) were calculated. Adjusted logistic regressions and Cox proportional hazards models for time to progression to IA were constructed.

Results

Compared with healthy controls (age adjusted where appropriate), ACPA+ individuals demonstrated reduced naïve (22.1% of subjects) and Treg (35.8%) frequencies and elevated IRC (29.5%). Of the 103 subjects, 48(46.6%) progressed. Individually, T cell subsets were weakly predictive (AUC between 0.63 and 0.66), although the presence of 2 T cell abnormalities had high specificity. Three models were compared: model-1 used T cell subsets only, model-2 used previously published clinical parameters, model-3 combined clinical data and T cell data. Model-3 performed the best (AUC 0.79 (95% CI 0.70 to 0.89)) compared with model-1 (0.75 (0.65 to 0.86)) and particularly with model-2 (0.62 (0.54 to 0.76)) demonstrating the added value of T cell subsets. Time to progression differed significantly between high-risk, moderate-risk and low-risk groups from model-3 (p=0.001, median 15.4 months, 25.8 months and 63.4 months, respectively).

Conclusions

T cell subset dysregulation in ACPA+ individuals predates the onset of IA, predicts the risk and faster progression to IA, with added value over previously published clinical predictors of progression.