A new model for an etiology of rheumatoid arthritis: smoking may trigger HLA-DR (shared epitope)-restricted immune reactions to autoantigens modified by citrullination

Crosstalk between B cells and neutrophils in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease without known cure that primarily affects synovial joints. RA has a prevalence of approximately 1% of the population worldwide. A vicious circle between two critical immune cell types, B cells and neutrophils, develops and promotes disease. Pathogenic anti‐citrullinated protein antibodies (ACPA) directed against a range of citrullinated epitopes are abundant in both plasma and synovial fluid of RA patients. In addition to stimulating numerous cell types, ACPA and other autoantibodies, notably rheumatoid factor, form immune complexes (ICs) that potently activate neutrophils. Attracted to the synovium by abundant chemokines, neutrophils are locally stimulated by ICs. They generate cytokines and release cytotoxic compounds including neutrophil extracellular traps (NETs), strands of decondensed chromatin decorated with citrullinated histones and granule‐derived neutrophil proteins, which are particularly abundant in the synovial fluid. In this way, neutrophils generate citrullinated epitopes and release peptidylarginine deiminase (PAD) enzymes capable of citrullinating extracellular proteins in the rheumatic joint, contributing to renewed ACPA generation. This review article focusses on the central function of citrullination, a post‐translational modification of arginine residues in RA. The discussion includes ACPA and related autoantibodies, somatic hypermutation‐mediated escape from negative selection by autoreactive B cells, promotion of the dominance of citrullinated antigens by genetic and lifestyle susceptibility factors and the vicious circle between ACPA‐producing pathogenic B cells and NET‐producing neutrophils in RA.

Cardiovascular risk factors in gout, psoriatic arthritis, rheumatoid arthritis and ankylosing spondylitis: a cross-sectional survey of patients in Western Sweden

Objectives

We aimed to compare traditional (trad) cardiovascular risk factors (CVRFs) among patients with gout, psoriatic arthritis (PsA), rheumatoid arthritis (RA) and ankylosing spondylitis (AS) stratified by sex.

Methods

A survey was sent to patients with gout (n=1589), PsA (n=1200), RA (n=1246) and AS (n=1095). Patients were retrieved from Sahlgrenska University Hospital, the hospitals of Uddevalla and Skövde, and 12 primary care centres in Western Sweden. The prevalence of self-reported trad-CVRFs was compared between diagnoses by age standardisation with the 2018 population of Sweden as the standard population.

Results

In total, 2896 (56.5%) of 5130 patients responded. Hypertension was the most frequently found comorbidity, reported by 65% of patients with gout, 41% with PsA, 43% with RA and 29% with AS. After age standardisation, women and men with gout had significantly more obesity (body mass index ≥30 kg/m²), hypertension, diabetes, hyperlipidaemia and multiple trad-CVRFs, compared with those with PsA, RA and AS. Obesity was significantly more common in PsA than in RA. In women, obesity, hypertension and multiple trad-CVRFs were more frequently reported in PsA than in RA and AS, whereas similar prevalence of CVRFs and coexistence of multiple trad-CVRFs were found in men with PsA, RA and AS.

Conclusions

Women and men with gout had the highest prevalence of trad-CVRFs. Differences in occurrence of CVRFs by sex were found in patients with PsA, RA and AS. In women, patients with PsA had higher occurrence of trad-CVRFs than those with RA and AS, whereas in men the distribution of CVRFs was similar in PsA, RA and AS.

Acetylated Diacylglycerol 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol in Autoimmune Arthritis and Interstitial Lung Disease in SKG Mice

Acetylated diacylglycerol 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) is a lipid molecule from the antlers of sika deer that might reduce inflammation by effectively controlling neutrophil infiltration, endothelial permeability and inflammatory chemokine production. Therefore, we evaluated the modulatory effect of PLAG on arthritis and interstitial lung disease (ILD) in an autoimmune arthritis model. We injected curdlan into SKG mice and PLAG was orally administered every day from 3 weeks to 20 weeks after the curdlan injection. The arthritis score was measured every week after the curdlan injection. At 20 weeks post-injection, the lung specimens were evaluated with H&E, Masson's trichrome and multiplexed immunofluorescent staining. Serum cytokines were also analyzed using a Luminex multiple cytokine assay. PLAG administration decreased the arthritis score until 8 weeks after the curdlan injection. However, the effect was not sustained thereafter. A lung histology revealed severe inflammation and fibrosis in the curdlan-induced SKG mice, which was attenuated in the PLAG-treated mice. Furthermore, immunofluorescent staining of the lung tissue showed a GM-CSF+ neutrophil accumulation and a decreased citrullinated histone 3 expression after PLAG treatment. PLAG also downregulated the levels of IL-6 and TNF-α and upregulated the level of sIL-7Rα, an anti-fibrotic molecule. Our results indicate that PLAG might have a preventative effect on ILD development through the resolution of NETosis in the lung.

Haplotype-Specific Expression Analysis of MHC Class II Genes in Healthy Individuals and Rheumatoid Arthritis Patients

HLA-DRB1 alleles have been associated with several autoimmune diseases. For anti-citrullinated protein antibody positive rheumatoid arthritis (RA), HLA-DRB1 shared epitope (SE) alleles are the major genetic risk factors. In order to study the genetic regulation of major histocompatibility complex (MHC) Class II gene expression in immune cells, we investigated transcriptomic profiles of a variety of immune cells from healthy individuals carrying different HLA-DRB1 alleles. Sequencing libraries from peripheral blood mononuclear cells, CD4+ T cells, CD8+ T cells, and CD14+ monocytes of 32 genetically pre-selected healthy female individuals were generated, sequenced and reads were aligned to the standard reference. For the MHC region, reads were mapped to available MHC reference haplotypes and AltHapAlignR was used to estimate gene expression. Using this method, HLA-DRB and HLA-DQ were found to be differentially expressed in different immune cells of healthy individuals as well as in whole blood samples of RA patients carrying HLA-DRB1 SE-positive versus SE-negative alleles. In contrast, no genes outside the MHC region were differentially expressed between individuals carrying HLA-DRB1 SE-positive and SE-negative alleles, thus HLA-DRB1 SE alleles have a strong cis effect on gene expression. Altogether, our findings suggest that immune effects associated with different allelic forms of HLA-DR and HLA-DQ may be associated not only with differences in the structure of these proteins, but also with differences in their expression levels.

Sputum Neutrophil Extracellular Trap Subsets Associate with IgA Anti-Citrullinated Protein Antibodies in Subjects At-Risk for Rheumatoid Arthritis

Objective

Mechanisms leading to anti–citrullinated protein antibody (ACPA) generation in rheumatoid arthritis (RA) are hypothesized to originate in the lung. We undertook this study to understand associations between neutrophil extracellular trap (NET) formation in the lung and local ACPA generation in subjects at risk of developing RA.

Methods

Induced sputum was collected from 49 subjects at risk of developing RA, 12 patients with RA, and 18 controls. Sputum neutrophils were tested for ex vivo NET formation, and sputum‐induced NET formation of control neutrophils was measured using immunofluorescence imaging. Sputum macrophages were tested for ex vivo endocytosis of apoptotic and opsonized cells. Levels of ACPA, NET remnants, and inflammatory proteins were quantified in sputum supernatant.

Results

Spontaneous citrullinated histone H3 (Cit‐H3)–expressing NET formation was higher in sputum neutrophils from at‐risk subjects and RA patients compared to controls (median 12%, 22%, and 0%, respectively; P < 0.01). In at‐risk subjects, sputum IgA ACPA correlated with the percentage of neutrophils that underwent Cit‐H3+ NET formation (r = 0.49, P = 0.002) and levels of Cit‐H3+ NET remnants (r = 0.70, P < 0.001). Reduced endocytic capacity of sputum macrophages was found in at‐risk subjects and RA patients compared to controls. Using a mediation model, we found that sputum inflammatory proteins were associated with sputum IgA ACPA through a pathway mediated by Cit‐H3+ NET remnants. Sputum‐induced Cit‐H3+ NET formation also correlated with sputum levels of interleukin‐1β (IL‐1β), IL‐6, and tumor necrosis factor in at‐risk subjects, suggesting a causal relationship.

Conclusion

These data support a potential mechanism for mucosal ACPA generation in subjects at risk of developing RA, whereby inflammation leads to increased citrullinated protein–expressing NETs that promote local ACPA generation.

The therapeutic dilemma of idiopathic granulomatous mastitis

INTRODUCTION

Idiopathic granulomatous mastitis (IGM) is a rare, benign, chronic breast condition that can cause repeated abscesses or mass formation in bilateral breasts. The condition can severely impact the quality of life of affected women. This study aims to evaluate effective treatment modalities, as well as understand the demographics and clinical presentation of patients with IGM.

METHODS

An 11-year retrospective review was performed of patients diagnosed with IGM from 1 January 2008 to 31 December 2018 at a tertiary breast unit.

RESULTS

A total of 77 patients were included in the study. The median age at presentation was 36 years old. IGM presented most commonly as a breast lump (98.1%). The median number of flares was 2 (1-12). Of the 77 patients, 68.8% (53) were treated with antibiotics, 50.6% (39) with steroids, and 44.2% (34) underwent surgery, in the course of their IGM treatment. Forty-five (59.2%) of the 76 patients with IGM required a multimodal treatment approach to achieve remission. There was no significant difference in the number of flares no matter the initial treatment (P=0.411), or subsequent treatment modality (P=0.343). Smokers had 10 times greater odds of having a "high flare" of IGM compared to those who did not smoke (P=0.031, odds ratio 10.444, 95% confidence interval 1.092-99.859).

CONCLUSION

IGM is a clinical diagnosis. It is a rare, relapsing breast inflammatory condition that affects young females with no superior treatment modality. Smoking is associated with higher number of flares of IGM and should be discouraged in IGM patients.

Specificity of Anti-Citrullinated Protein Antibodies to Citrullinated α-Enolase Peptides as a Function of Epitope Structure and Composition

Rheumatoid arthritis (RA) is an autoimmune disease affecting approximately 1-2% of the world population. In addition to the first discovered serologic markers for RA, the rheumatoid factors (RFs), anti-citrullinated protein antibodies (ACPAs) are even more specific for the disease compared to RFs and are found in 70-80% of RA patient sera. RA etiopathogenesis still needs to be elucidated, as different factors are proposed to be involved, such as Epstein-Barr virus infection. Hence, understanding the interaction between ACPAs and their citrullinated peptide targets is relevant for a better knowledge of RA pathophysiology and for diagnostic purposes. In this study, a cohort of RA sera, healthy control sera and multiple sclerosis sera were screened for reactivity to a variety of citrullinated peptides originating from α-enolase, pro-filaggrin, proteoglycan and Epstein-Barr nuclear antigen-2 by enzyme-linked immunosorbent assay. ACPA reactivity to citrullinated α-enolase peptides was found to depend on peptide length and peptide conformation, favouring cyclic (disulfide bond) conformations for long peptides and linear peptides for truncated ones. Additional investigations about the optimal peptide conformation for ACPA detection, employing pro-filaggrin and EBNA-2 peptides, confirmed these findings, indicating a positive effect of cyclization of longer peptides of approximately 20 amino acids. Moreover, screening of the citrullinated peptides confirmed that ACPAs can be divided into two groups based on their reactivity. Approximately 90% of RA sera recognize several peptide targets, being defined as cross-reactive or overlapping reactivities, and whose reactivity to the citrullinated peptide is considered primarily to be backbone-dependent. In contrast, approximately 10% recognize a single target and are defined as nonoverlapping, primarily depending on the specific amino acid side-chains in the epitope for a stable interaction. Collectively, this study contributed to characterize epitope composition and structure for optimal ACPA reactivity and to obtain further knowledge about the cross-reactive nature of ACPAs.

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

INTRODUCTION

Autoantibodies such as IgM rheumatoid factor (RF) and anti-citrullinated proteins/peptides antibodies (ACPA) have previously been incriminated in systemic bone loss in rheumatoid arthritis (RA). There are, however, no data describing association of IgA RF and IgG RF with systemic bone loss.

OBJECTIVE

This study was aimed to investigate the association of RF isotypes with systemic bone loss among patients with RA.

METHODS

RF isotypes and ACPA were measured by enzyme-linked immunosorbent assay among 153 patients with RA. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry.

RESULTS

Ninety-four (61.4%) patients had positive IgA RF, 89 (58.2%) had positive IgG RF, 109 (71.2%) had positive IgM RF, whereas 122 (80.3%) RA patients tested positive for ACPA. Compared to the IgA RF-negative patients, IgA RF-positive patients exhibited higher disease activity and had higher RF titers. Seven (4.6%) patients had low BMD at femoral neck, 12 (7.8%) at total femur, and 47 (30.7%) at lumbar spine. IgA RF was found to be associated with protection against low BMD at spine (OR = 0.47, 95% CI = 0.23-0.95, p = 0.034). This association was further confirmed in the multivariate regression analysis taking into account several potential confounding factors (OR = 0.21, 95% CI = 0.06-0.65, p = 0.039). No association between low BMD and the presence of IgG RF or IgM RF or ACPA was found.

CONCLUSION

IgA RF for the first time ever was shown to be associated with BMD preservation at spine in RA. Key points • IgA RF was associated with protection against low spinal BMD. • No association between low BMD and the presence of IgG RF or IgM RF was found.

Cohort profile: SCREEN-RA: design, methods and perspectives of a Swiss cohort study of first-degree relatives of patients with rheumatoid arthritis

PURPOSE

Rheumatoid arthritis (RA) is an insidious autoimmune disease, with an immunological onset years before diagnosis. Early interventions in preclinical stages could prevent or minimise the progression towards irreversible joint damage. The SCREEN-RA cohort (Evaluation of a SCREENing strategy for Rheumatoid Arthritis) aims to characterise the preclinical stages of the disease, to identify environmental risk factors, and to discover or validate novel biomarkers predictive for RA development.

PARTICIPANTS

SCREEN-RA includes an at-risk population for RA, namely first-degree relatives of patients with established RA.

FINDINGS TO DATE

The cohort started in 2009 is composed of mostly asymptomatic healthy individuals (total n=1458, 7262 person-years), with a mean age of 44 years at enrolment, 74% female and 91% Caucasian ethnicity. During the study period, 16 participants have developed RA. All participants provide baseline serum, DNA and RNA samples, and in a subset, stool samples and oral examination are performed for microbiota assessment. At enrolment, 10% of participants had asymptomatic autoimmunity associated with RA (n=147), 10% presented 'clinically suspect arthralgias' (n=143) and 3% reported arthralgias in conjunction with autoimmunity or high genetic risk (n=51). Studies with this cohort have uncovered risk factors for RA development, such as female hormonal factors, poor oral health or intestinal dysbiosis.

FUTURE PLANS

Future directions include immunological and 'multiomics' approaches to discover new biological markers of progression towards RA, as well as testing preventive interventions in 'high-risk' population.

Citrullinated vimentin mediates development and progression of lung fibrosis

The mechanisms by which environmental exposures contribute to the pathogenesis of lung fibrosis are unclear. Here, we demonstrate an increase in cadmium (Cd) and carbon black (CB), common components of cigarette smoke (CS) and environmental particulate matter (PM), in lung tissue from subjects with idiopathic pulmonary fibrosis (IPF). Cd concentrations were directly proportional to citrullinated vimentin (Cit-Vim) amounts in lung tissue of subjects with IPF. Cit-Vim amounts were higher in subjects with IPF, especially smokers, which correlated with lung function and were associated with disease manifestations. Cd/CB induced the secretion of Cit-Vim in an Akt1- and peptidylarginine deiminase 2 (PAD2)-dependent manner. Cit-Vim mediated fibroblast invasion in a 3D ex vivo model of human pulmospheres that resulted in higher expression of CD26, collagen, and α-SMA. Cit-Vim activated NF-κB in a TLR4-dependent fashion and induced the production of active TGF-β1, CTGF, and IL-8 along with higher surface expression of TLR4 in lung fibroblasts. To corroborate ex vivo findings, mice treated with Cit-Vim, but not Vim, independently developed a similar pattern of fibrotic tissue remodeling, which was TLR4 dependent. Moreover, wild-type mice, but not PAD2^-/- and TLR4 mutant (MUT) mice, exposed to Cd/CB generated high amounts of Cit-Vim, in both plasma and bronchoalveolar lavage fluid, and developed lung fibrosis in a stereotypic manner. Together, these studies support a role for Cit-Vim as a damage-associated molecular pattern molecule (DAMP) that is generated by lung macrophages in response to environmental Cd/CB exposure. Furthermore, PAD2 might represent a promising target to attenuate Cd/CB-induced fibrosis.

Towards prevention of autoimmune diseases: The example of rheumatoid arthritis

Prevention is the ultimate aim for clinicians and scientists concerned with severe diseases, like many immune-mediated conditions. Here, we describe recent progress in the understanding of etiology and molecular pathogenesis of rheumatoid arthritis (RA), which make this disease a potential prototype for prevention that may include both public health measures and targeted and personalized approaches that we call "personalized prevention." Critical components of this knowledge are (i) better understanding of the dynamics of the RA-associated autoimmunity that may begin many years before onset of joint inflammation; (ii) insights into how this immunity may be triggered at mucosal surfaces after distinct environmental challenges; (iii) better understanding of which features of the pre-existing immunity may cause symptoms that precede joint inflammation and predict a high risk for imminent arthritis development; and (iv) how molecular events occurring before onset of inflammation might be targeted by existing or future therapies, ultimately by specific targeting of Major histocompatibility complex (MHC) class II restricted and RA-specific immunity. Our main conclusion is that studies and interventions in the phase of autoimmunity preceding RA offer new opportunities to prevent the disease and thereby also understand the molecular pathogenesis of its different variants.

Association between number and type of different ACPA fine specificities with lung abnormalities in early, untreated rheumatoid arthritis

Background

Rheumatoid arthritis (RA)-associated anticitrullinated protein/peptide antibodies (ACPA) might originate at mucosal sites such as the lungs. We aimed to examine the relationship between the ACPA repertoire and lung abnormalities on high-resolution CT (HRCT) in patients with earlyuntreated RA.

Methods

106 patients with newly diagnosed untreated RA were examined with HRCT of the lungs. Blood samples were analysed for presence of rheumatoid factor (RF) and ACPA using either a CCP2 detection kit or an immunochip containing 10 different citrullinated peptides. Association between HRCT findings and the antibody repertoire was assessed by logistic regression analysis.

Results

The number (%) of patients with HRCT abnormalities was 58 (54.7%) for parenchymal abnormalities and 68 (64.2%) for airway abnormalities. CCP2 IgG, RF IgA and antibodies against citrullinated fibrinogen were associated with the presence of parenchymal lung abnormalities. Interestingly, a high number of ACPA fine specificities gave a high risk of having parenchymal lung abnormalities at the time of RA diagnosis. No significant signals were identified between ACPA specificities and risk for airway abnormalities.

Conclusions

The presence of RF and ACPAs (especially against citrullinated fibrinogen peptides) as well as high number of ACPAs fine specificities are associated with parenchymal lung abnormalities in patients with early, untreated RA. This provides further support for an important pathogenic link between the lung and systemic autoimmunity, contributing to RA development.

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

Association between HLA alleles and Epstein-Barr virus Zta-IgA serological status in healthy males from southern China

Background

Nasopharyngeal carcinoma (NPC), an Epstein–Barr virus (EBV) associated cancer, exhibits an extremely high incidence in southern Chinese. Given that human leukocyte antigen (HLA) plays critical roles in antigen presentation and relates to NPC susceptibility, it is speculated that certain HLA variants may affect EBV reactivation, which is a key pathogenic factor of NPC. Therefore, we attempted to identify HLA alleles associated with the indicator of EBV reactivation, Zta‐IgA, in healthy males from NPC endemic area.

Methods

HLA alleles of 1078 healthy males in southern China from the 21‐RCCP study were imputed using genome‐wide single nucleotide polymorphism data. EBV Zta‐IgA in blood samples were measured using an enzyme‐linked immunosorbent assay. Multiple logistic regression analysis was used to evaluate the effect of HLA allele on Zta‐IgA serological status and its potential joint association with smoking. The binding affinity for Zta‐peptide was predicted using NetMHCIIpan 4.0.

Results

HLA‐DRB1*09:01 was found to be associated with a higher risk of Zta‐IgA seropositivity (odds ratio = 1.80, 95% confidence interval = 1.32–2.45; p = 1.82 × 10⁻⁴). Compared with non‐smokers without HLA‐DRB1*09:01, the effect size increased to 2.19‐ and 3.70‐fold for the light and heavy smokers carrying HLA‐DRB1*09:01, respectively. Furthermore, HLA‐DRB1*09:01 showed a stronger binding affinity to Zta peptide than other HLA‐DRB1 alleles.

Conclusions

Our study highlighted the pivotal role of genetic HLA variants in EBV reactivation and the etiology of NPC. Smokers with HLA‐DRB1*09:01 have a significantly higher risk of being Zta‐IgA seropositive, which indicates the necessity of smoking cessation in certain high‐risk populations and also provide clues for further research on the etiology of NPC.

Indoor solid fuel use and incident arthritis among middle-aged and older adults in rural China: A nationwide population-based cohort study

BACKGROUND

Many households in developing countries, including China, rely on the traditional use of solid fuels for cooking and heating. Arthritis is highly prevalent in middle-aged and older adults and is a major cause of disability. However, evidence linking indoor solid fuel use with arthritis is scarce in this age group (≥45 years) in developing countries.

OBJECTIVES

To investigate whether exposure to indoor solid fuel for cooking and heating is associated with arthritis in middle-aged and older adults in rural China.

METHODS

Data for the present study were extracted from the China Health and Retirement Longitudinal Study (CHARLS), a longitudinal national prospective study of adults aged 45 years and older enrolled in 2010 and followed up through 2015. We included 7807 rural participants without arthritis at baseline, of whom 1548 living in a central heating area in winter were included in the heating analysis (taking the Qinling-Huaihe line as the heating boundary). Cox proportional hazards models were used to examine the association between indoor solid fuel use and arthritis, controlling for age, sex, education, marital status, smoking status, drinking status, self-reported socioeconomic status, BMI, sleep time, napping time, independent cooking, hypertension, diabetes, dyslipidemia, heart problems and stroke. We also investigated the effect of switching primary fuels and using solid fuels for both cooking and heating on arthritis risk.

RESULTS

The mean (SD) age of the study participants was 59.2 (10.0) years old, and 48.0% of participants were women. A total of 64.8% and 63.0% of the participants reported primarily using solid fuel for cooking and heating, respectively. Arthritis incidence rates were lower among clean fuel users than solid fuel users. Compared to those using clean fuels, cooking and heating solid fuel users had a higher risk of arthritis, with hazard ratios (HRs) of 1.22 (95% confidence interval (CI): 1.01, 1.49) and 1.76 (95% CI: 1.07, 2.89), respectively. Switching from clean fuels to solid fuels for heating (HR: 3.28, 95% CI: 1.21, 7.91) and using solid fuels for both cooking and heating (HR, 1.71, 95% CI, 1.01-2.79) increased the risk of arthritis.

CONCLUSIONS

Long-term solid fuel use for indoor cooking and heating is associated with an increased risk of arthritis events among adults aged 45 years and older in rural China. The potential benefits of reducing indoor solid fuel use in groups at high risk for arthritis merit further exploration.

Hydroquinone Exposure Worsens Rheumatoid Arthritis through the Activation of the Aryl Hydrocarbon Receptor and Interleukin-17 Pathways

Rheumatoid arthritis (RA) development is strongly associated with cigarette smoke exposure, which activates the aryl hydrocarbon receptor (AhR) as a trigger for Th17 inflammatory pathways. We previously demonstrated that the exposure to hydroquinone (HQ), one of the major compounds of cigarette tar, aggravates the arthritis symptomatology in rats. However, the mechanisms related to the HQ-related RA still remain elusive. Cell viability, cytokine secretion, and gene expression were measured in RA human fibroblast-like synoviocytes (RAHFLS) treated with HQ and stimulated or not with TNF-α. Antigen-induced arthritis (AIA) was also elicited in wild type (WT), AhR ^−/− or IL-17R ^−/− C57BL/6 mice upon daily exposure to nebulized HQ (25ppm) between days 15 to 21. At day 21, mice were challenged with mBSA and inflammatory parameters were assessed. The in vitro HQ treatment up-regulated TNFR1, TNFR2 expression, and increased ROS production. The co-treatment of HQ and TNF-α enhanced the IL-6 and IL-8 secretion. However, the pre-incubation of RAHFLS with an AhR antagonist inhibited the HQ-mediated cell proliferation and gene expression profile. About the in vivo approach, the HQ exposure worsened the AIA symptoms (edema, pain, cytokines secretion and NETs formation) in WT mice. These AIA effects were abolished in HQ-exposed AhR ^−/− and IL-17R ^−/− animals though. Our data demonstrated the harmful HQ influence over the onset of arthritis through the activation and proliferation of synoviocytes. The HQ-related RA severity was also associated with the activation of AhR and IL-17 pathways, highlighting how cigarette smoke compounds can contribute to the RA progression.

Tumour necrosis factor inhibitors reduce aortic stiffness progression in patients with long-standing rheumatoid arthritis

BACKGROUND

Aortic stiffness index (AoSI) has to be considered a proxy outcome measure in patients with rheumatoid arthritis (RA). The aim of this study was to comparatively describe AoSI progression in two groups of RA patients on long-term treatment with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) with or without tumour necrosis factor inhibitors (TNFi).

METHODS

AoSI was evaluated by Doppler echocardiography at the level of the aortic root, using a two-dimensional guided M-mode evaluation. Eligible participants were assessed at baseline and after 12 months. Changes in serum lipids, glucose and arterial blood pressure were assessed. All patients who did not change DMARD treatment during follow-up were consecutively selected for this study.

RESULTS

We included 107 (64 TNFi and 43 csDMARDs) RA patients. Most patients (74%) were in remission or low disease activity and had some CVD risk factors (45.8% hypertension, 59.8% dyslipidaemia, 45.3% smoking). The two groups did not differ significantly for baseline AoSI (5.95±3.73% vs 6.08±4.20%, p=0.867). Follow-up AoSI was significantly increased from baseline in the csDMARDs group (+1.00%; p<0.0001) but not in the TNFi group (+0.15%, p=0.477). Patients on TNFi had significantly lower follow-up AoSI from baseline than the csDMARDs group (-1.02%, p<0.001; ANCOVA corrected for baseline AoSI, age and systolic blood pressure). Furthermore, follow-up AoSI was significantly lower in TNFi than in csDMARDs users with an increasing number of CVD risk factors.

CONCLUSION

Long-term treatment with TNFi was associated with reduced aortic stiffness progression in patients with established RA and several CVD risk factors.

Association Between Baseline Anti-cyclic Citrullinated Peptide Antibodies and 6-Month Clinical Response Following Abatacept or TNF Inhibitor Treatment: A Real-World Analysis of Biologic-Experienced Patients with RA

INTRODUCTION

Anti-cyclic citrullinated peptide (anti-CCP) antibodies are associated with poor prognosis in patients with rheumatoid arthritis (RA). Previous data from randomized controlled trials and clinical practice have shown anti-CCP-positive (+) patients had a better response to treatment with abatacept or tumor necrosis factor inhibitor (TNFi) treatment than those who were anti-CCP negative. This study assessed the association between baseline anti-CCP2 [a surrogate for anti-citrullinated protein antibody (ACPA)] concentration and 6-month treatment responses to abatacept or TNFi in patients with RA.

METHODS

This real-world analysis included biologic-experienced patients from CERTAIN (Comparative Effectiveness Registry to study Therapies for Arthritis and Inflammatory CoNditions) who initiated abatacept or TNFi, had prior biologic disease-modifying drug exposure and baseline anti-CCP2 concentration/serostatus and serum samples (baseline and 6 months). Baseline demographics and disease characteristics were compared. Change from baseline at 6 months in Clinical Disease Activity Index (CDAI) score and patient-reported outcomes [PROs: pain, fatigue, patient global assessment (PtGA), modified Health Assessment Questionnaire (mHAQ) score], by baseline anti-CCP2 quartile and binary cut-off (> 10-250 and > 250 U/ml), were evaluated separately in the abatacept and TNFi groups using a linear regression model adjusted for age, sex, CDAI/PROs, comorbidity index, and methotrexate use.

RESULTS

Included were 138 abatacept and 137 TNFi initiators who were anti-CCP2+. At baseline, there were significant differences between anti-CCP2 quartiles and mean CDAI, swollen joint count 28, C-reactive protein (CRP), Disease Activity Score 28 (CRP), rheumatoid factor (RF), mHAQ and physician global assessment among abatacept initiators, and in mean RF, mHAQ, and PtGA among TNFi initiators. Among abatacept (but not TNFi) initiators, CDAI numerically improved (p = 0.208) and PROs significantly improved (p < 0.05) with increasing baseline anti-CCP2.

CONCLUSIONS

In patients treated with abatacept, not TNFi, higher anti-CCP2 concentrations at baseline were associated with numerically greater improvements in CDAI and significant improvements in PROs after 6 months.

CLINICAL TRIAL NUMBER

NCT01625650.

Adaptive immunity in the joint of rheumatoid arthritis

Adaptive immunity plays central roles in the pathogenesis of rheumatoid arthritis (RA), as it is regarded as an autoimmune disease. Clinical investigations revealed infiltrations of B cells in the synovium, especially those with ectopic lymphoid neogenesis, associate with disease severity. While some B cells in the synovium differentiate into plasma cells producing autoantibodies such as anti-citrullinated protein antibody, others differentiate into effector B cells producing proinflammatory cytokines and expressing RANKL. Synovial B cells might also be important as antigen-presenting cells. Synovial T cells are implicated in the induction of antibody production as well as local inflammation. In the former, a recently identified CD4 T cell subset, peripheral helper T (Tph), which is characterized by the expression of PD-1 and production of CXCL13 and IL-21, is implicated, while the latter might be mediated by Th1-like CD4 T cell subsets that can produce multiple proinflammatory cytokines, including IFN-γ, TNF-α, and GM-CSF, and express cytotoxic molecules, such as perforin, granzymes and granulysin. CD8 T cells in the synovium are able to produce large amount of IFN-γ. However, the involvement of those lymphocytes in the pathogenesis of RA still awaits verification. Their antigen-specificity also needs to be clarified.

Challenges and Opportunities of Targeted Behavioral Interventions for Groups at Risk for Developing Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA) is a serious autoimmune disease which causes painful, swollen joints and can impact quality of life and increase morbidity and mortality. There are several preclinical stages of RA that correspond to at-risk groups that include: genetic risk, risk from behaviors, elevation of RA-related autoantibodies, and early clinical disease manifestations such as undifferentiated arthritis. Early interventions are crucial to slowing progression to and potentially preventing RA onset. Modification of behaviors among at-risk individuals may decrease RA risk. There are several challenges and opportunities in implementing preventative behavioral interventions, which may vary within different at-risk groups. Methods: We performed a narrative review of the literature, including meta-analyses focused on RA risk-related behaviors as well as publications investigating the potential efficacy of behavioral modifications on RA risk. Results: There are multiple behavioral risk factors associated with RA, including smoking, obesity, low physical activity, low quality diet, and poor dental hygiene, which may contribute to progression to clinical RA. Meta-analyses have been performed for smoking, excess body weight, and physical activity. Likelihood of adopting behavioral modifications may increase as RA risk increases. Conclusions: Clinicians may be able to tailor preventative approaches to various RA at-risk groups to help reduce RA risk, but further research is needed. A better understanding of the relationship of behaviors with RA risk and optimized approaches to implementing behavioral changes may allow for clinicians to tailor their preventative approaches for at-risk individuals.

Interplay of Microbiota and Citrullination in the Immunopathogenesis of Rheumatoid Arthritis

Microbiota is a balanced ecosystem that has important functions to the host health including development, defense, digestion, and absorption of dietary fibers and minerals, vitamin synthesizes, protection, and training the host immune system. On the other hand, its dysbiosis is linked to many human diseases such as rheumatoid arthritis (RA). The RA is an inflammatory autoimmune disorder caused by genetic and environmental factors; microbiota may be considered as a risk environmental factor for it. Citrullination is a post-translation modification (PMT) that converts the amino acid arginine to amino acid citrulline in certain proteins. These citrullinated proteins are recognized as a foreign antigen by the immune system resulting in the upregulation of inflammatory action such as in RA. The current work highlights the effect of both gut and oral microbiota dysbiosis on the development of RA, as well as discusses how the alteration in microbiota composition leads to the overgrowth of some bacterial species that entangled in RA pathogenicity. The evidence suggested that some oral and gut microbial species such as Porphyromonas gingivalis and Prevotella copri, respectively, contribute to RA pathogenesis. During dysbiosis, these bacteria can mediate the citrullination of either human or bacteria proteins to trigger an immune response that leads to the generation of autoantibodies.

Antigen-driven autoantibody production in lungs of interstitial lung disease with autoimmune disease

Interstitial lung disease (ILD) sometimes becomes a life-threatening complication of systemic autoimmune diseases; however, little is known about the immune response in lung lesions. We aimed to investigate humoural immunity in ILD associated with rheumatoid arthritis (RA), sjögren's syndrome (SjS), and mixed connective tissue disease (MCTD), using bronchoalveolar fluid (BALF) and serum samples from 15 patients with autoimmune disease associated-ILD. We first showed that BALF contained higher titers of disease-related autoantibodies than serum, suggesting the possibility of autoantibody production in lungs. Next, we produced 326 monoclonal antibodies from antibody-secreting cells in BALF, and the reactivity and their revertants, in which somatic hypermutations were reverted to germline, were analyzed. Among 123 antibodies from RA-ILD, 16 disease-related antibodies (anti-modified protein antibodies and rheumatoid factors) were identified, of which one antibody had both properties. The revertant antibodies changed their target modification in a complicated manner, suggesting that the antibodies were selected against various modifications in lungs. Among 146 antibodies from SjS-ILD and/or MCTD-ILD, seven anti-SSA/Ro60 antibodies and 15 anti-RNP antibodies were identified. Some of the anti-RNP antibodies recognized multiple RNP constituent proteins simultaneously, indicating that epitope spreading may progress in lungs. Our results revealed the existence of an active autoimmunity in the lungs of autoimmune disease associated-ILD.

Probiotics and Amelioration of Rheumatoid Arthritis: Significant Roles of Lactobacillus casei and Lactobacillus acidophilus

Rheumatoid arthritis is a chronic autoimmune disorder that can lead to disability conditions with swollen joints, pain, stiffness, cartilage degradation, and osteoporosis. Genetic, epigenetic, sex-specific factors, smoking, air pollution, food, oral hygiene, periodontitis, Prevotella, and imbalance in the gastrointestinal microbiota are possible sources of the initiation or progression of rheumatoid arthritis, although the detailed mechanisms still need to be elucidated. Probiotics containing Lactobacillus spp. are commonly used as alleviating agents or food supplements to manage diarrhea, dysentery, develop immunity, and maintain general health. The mechanism of action of Lactobacillus spp. against rheumatoid arthritis is still not clearly known to date. In this narrative review, we recapitulate the findings of recent studies to understand the overall pathogenesis of rheumatoid arthritis and the roles of probiotics, particularly L. casei or L. acidophilus, in the management of rheumatoid arthritis in clinical and preclinical studies.

Association of AFF3 Gene Polymorphism rs10865035 with Rheumatoid Arthritis: A Population-Based Case-Control Study on a Pakistani Cohort

Rheumatoid arthritis (RA) is one of the complex diseases with the involvement of the genetic as well as environmental factors in its onset and severity. Different genome-wide association and candidate gene studies have shown the role of several genetic variants in multiple loci/genes with ethnical and geographical variations. This study was designed to detect the association of a single-nucleotide polymorphism (SNP) rs10865035 in the AFF3 gene with the genetic background of rheumatoid arthritis (RA) in the Pakistani cohort. A total of 703 individuals, including 409 RA patients and 294 healthy controls, were genotyped using TaqMan assay and Tri primer ARMS-PCR (amplification-refractory mutation system-polymerase chain reaction) methods. The association of rs10865035 with the RA was statistically determined using different models. Interestingly, besides the homozygous recessive model (G/G vs. A/G + A/A) (OR = 1.693(1.06-2.648); P = 0.025), all other models, which included the codominant (χ 2 = 5.169; P = 0.075), homozygous dominant (A/A vs. G/G + A/G) (OR = 0.867 (0.636-1.187); P = 0.41), heterozygous (A/G vs. A/A + GG) (OR = 0.491 (0.667-1.215); P = 0.49), and additive model (OR = 0.826 (0.665-1.027); P = 0.08) showed insignificant distribution of the genotypes among the cases and controls. These findings suggest that the AFF3 gene (rs10865035) has no significant role in the onset of RA in the Pakistani population.

Autoantibodies in Rheumatoid Arthritis - Laboratory and Clinical Perspectives

Measurement of two groups of autoantibodies, rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPA) have gained increasing significance in the diagnosis and classification of rheumatoid arthritis (RA) over the last 65 years. Despite this rising importance of autoimmune serology in RA, there is a palpable lack of harmonization between different commercial RF and ACPA tests. While a minimal diagnostic specificity has been defined for RF tests, which almost always are related to an international reference preparation, neither of this applies to ACPA. Especially assays with low diagnostic specificity are associated with very low positive predictive values or post-test probabilities in real world settings. In this review we focus on issues of practical bearing for the clinical physician diagnosing patients who potentially have RA, or treating patients diagnosed with RA. We advocate that all clinically used assays for RF and ACPA should be aligned to a common diagnostic specificity of 98-99% compared to healthy controls. This high and rather narrow interval corresponds to the diagnostic specificity seen for many commercial ACPA tests, and represents a specificity that is higher than what is customary for most RF assays. Data on antibody occurrence harmonized in this way should be accompanied by test result-specific likelihood ratios for the target diagnosis RA on an ordinal or interval scale, which will provide the clinical physician with more granular and richer information than merely relating numerical values to a single cut-off point. As many physicians today are used to evaluate autoantibodies as positive or negative on a nominal scale, the introduction of test result-specific likelihood ratios will require a change in clinical mindset. We also discuss the use of autoantibodies to prognosticate future arthritis development in at-risk patients as well as predict severe disease course and outcome of pharmacological treatment.

Elevated Anti-Citrullinated Protein Antibodies Prior to Rheumatoid Arthritis Diagnosis and Risks for Chronic Obstructive Pulmonary Disease or Asthma

OBJECTIVE

To investigate elevation of anti-citrullinated protein antibodies (ACPAs) before diagnosis of rheumatoid arthritis (RA) and risks for chronic obstructive pulmonary disease (COPD) or asthma.

METHODS

We performed a matched cohort study nested within the Nurses' Health Studies among women who donated blood. Women with incident RA after blood draw (self-reported, then confirmed by medical records) were each matched to 3 controls by age, cohort, year, and menopausal factors. Pre-RA ACPA positivity was defined as >99th percentile of control distribution by a research assay or by cyclic citrullinated peptide in a subset. Incident COPD and asthma after index date (date of blood draw) were identified by questionnaires. Cox regression estimated hazard ratios (HRs) for incident COPD or asthma (in separate analyses) associated with pre-RA, pre-RA ACPA+, or pre-RA ACPA- phenotypes each compared to their matched non-RA controls.

RESULTS

We analyzed 283 women who were pre-RA and 842 controls; blood was donated a mean ± SD of 9.7 ± 5.8 years before RA diagnosis. Fifty-nine women (20.8%) were pre-RA ACPA+. There were 107 cases of incident COPD and 105 incident asthma cases during 21,489 person-years of follow-up. Pre-RA ACPA+ was associated with increased COPD risk (HR 3.04 [95% confidence interval (95% CI) 1.33-7.00]) after adjusting for covariates including smoking pack-years. Pre-RA ACPA+ had an HR for asthma of 1.74 (multivariable 95% CI 0.72-4.24), similar to the risk of asthma for pre-RA ACPA- (HR 1.65 [95% CI 1.11-2.46]).

CONCLUSION

Women with elevated ACPA before RA diagnosis had increased risk for developing COPD compared to controls. Women who later developed RA were more likely to develop asthma than controls, regardless of pre-RA ACPA status.

The gut-joint axis in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disorder that primarily affects the joints. One hypothesis for the pathogenesis of RA is that disease begins at mucosal sites as a consequence of interactions between the mucosal immune system and an aberrant local microbiota, and then transitions to involve the synovial joints. Alterations in the composition of the microbial flora in the lungs, mouth and gut in individuals with preclinical and established RA suggest a role for mucosal dysbiosis in the development and perpetuation of RA, although establishing whether these alterations are the specific consequence of intestinal involvement in the setting of a systemic inflammatory process, or whether they represent a specific localization of disease, is an ongoing challenge. Data from mouse models of RA and investigations into the preclinical stages of disease also support the hypothesis that these alterations to the microbiota predate the onset of disease. In addition, several therapeutic options widely used for the treatment of RA are associated with alterations in intestinal microbiota, suggesting that modulation of intestinal microbiota and/or intestinal barrier function might be useful in preventing or treating RA.

The pre-clinical phase of rheumatoid arthritis: From risk factors to prevention of arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease considered as a multistep process spanning from the interaction of genetic (e.g., shared epitope or non-HLA loci), environmental and behavioral risk factors (e.g., smoking) leading to breaking immune tolerance and autoimmune processes such as the production of autoantibodies (e.g., antibodies against citrullinated proteins ACPA or rheumatoid factors, RF), development of the first symptoms without clinical arthritis, and, finally, the manifestation of arthritis. Despite the typical joint involvement in established RA, the pathogenesis of the disease likely begins far from joint structures: in the lungs or periodontium in association with citrullination, intestinal microbiome, or adipose tissue, which supports normal findings in synovial tissue in ACPA+ patients with arthralgia. The presence of ACPA is detectable even years before the first manifestation of RA. The pre-clinical phase of RA is the period preceding clinically apparent RA with ACPA contributing to the symptoms without subclinical inflammation. While the combination of ACPA and RF increases the risk of progression to RA by up to 10 times, increasing numbers of novel autoantibodies are to be investigated to contribute to the increased risk and pathogenesis of RA. With growing knowledge about the course of RA, new aspiration emerges to cure and even prevent RA, shifting the "window of opportunity" to the pre-clinical phases of RA. The clinical definition of individuals at risk of developing RA (clinically suspect arthralgia, CSA) makes it possible to unify these at-risk individuals' clinical characteristics for "preventive" treatment in ongoing clinical trials using mostly biological or conventional synthetic disease-modifying drugs. However, the combination of symptoms, laboratory, and imaging biomarkers may be the best approach to select the correct target at-risk population. The current review aims to explore different phases of RA and discuss the potential of (non)pharmacological intervention aiming to prevent RA.

Biological classification of childhood arthritis: roadmap to a molecular nomenclature

Chronic inflammatory arthritis in childhood is heterogeneous in presentation and course. Most forms exhibit clinical and genetic similarity to arthritis of adult onset, although at least one phenotype might be restricted to children. Nevertheless, paediatric and adult rheumatologists have historically addressed disease classification separately, yielding a juvenile idiopathic arthritis (JIA) nomenclature that exhibits no terminological overlap with adult-onset arthritis. Accumulating clinical, genetic and mechanistic data reveal the critical limitations of this strategy, necessitating a new approach to defining biological categories within JIA. In this Review, we provide an overview of the current evidence for biological subgroups of arthritis in children, delineate forms that seem contiguous with adult-onset arthritis, and consider integrative genetic and bioinformatic strategies to identify discrete entities within inflammatory arthritis across all ages.

Shared epitope and polymorphism of MICA and NKG2D encoding genes in Greek and Polish patients with rheumatoid arthritis

The present study aimed to analyse and compare the distribution of MICA (rs1051792) and NKG2D/KLRK1 (rs1154831, rs1049174, rs2255336) polymorphisms in 61 Greek and 100 Polish patients with rheumatoid arthritis in relation to the presence of the HLA-DRB1 shared epitope and clinical parameters. Genotyping of selected polymorphism was performed using real-time PCR. HLA-DRB1 shared epitope alleles segregated differently in Greek and Polish patients but in both populations were detected in over 60% of cases. The rs1051792-A variant was more common among SE-positive Polish patients (p = 0.003) while the rs1049174-G allele was more frequently observed in Greeks than in Poles (p < 0.001). Moreover, among Greek patients, the rs1051792-GG homozygotes more frequently presented with anti-CCP antibodies and rheumatoid factor (RF), while carriers of the rs1049174-G variant and rs1154831-CC homozygotes were characterized by lower disease activity scores (p < 0.05 in all cases). These results imply that, in addition to the HLA-DRB1 SE alleles, MICA and NKG2D polymorphisms may also play a role in rheumatoid arthritis.

Association of Agricultural, Occupational, and Military Inhalants With Autoantibodies and Disease Features in US Veterans With Rheumatoid Arthritis

OBJECTIVE

To determine the association of inhalant exposures with rheumatoid arthritis (RA)-related autoantibodies and severity in US veterans.

METHODS

Participants in the Veterans Affairs Rheumatoid Arthritis (VARA) registry were mailed surveys assessing occupational, agricultural, and military inhalant exposures. Demographic characteristics, disease activity, functional status, and extraarticular features were obtained from the VARA registry, while HLA-DRB1 shared epitope (SE) status, anti-cyclic citrullinated peptide (anti-CCP) antibodies, and rheumatoid factor (RF) were measured using banked DNA/serum from enrollment. Associations between inhalant exposures and RA-related factors (autoantibodies, severity, and extraarticular features) were assessed using multivariable linear and logistic regression models adjusted for age, sex, race, and tobacco use and stratified by SE status. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Questionnaires were returned by 797 of 1,566 participants (50.9%). Survey respondents were older, more often White or male, and less frequently smokers, and had lower disease activity compared to nonrespondents. Anti-CCP positivity was more common among veterans exposed to burn pits (OR 1.66 [95% CI 1.02, 2.69]) and military waste disposal (OR 1.74 [95% CI 1.04, 2.93]) independent of other factors. Among participants who were positive for SE alleles, burn pit exposure (OR 5.69 [95% CI 2.73, 11.87]) and military waste disposal exposure (OR 5.05 [95% CI 2.42, 10.54]) were numerically more strongly associated with anti-CCP positivity. Several inhalant exposures were associated with the presence of chronic lung disease, but not with the presence of RF or the level of disease activity.

CONCLUSION

Military burn pit exposure and military waste disposal exposure were independently associated with the presence of anti-CCP antibodies in RA patients. These findings are consistent with emerging evidence that various inhalant exposures influence autoantibody expression and RA risk.

Rheumatic Complications of Immune Checkpoint Inhibitors

Immune checkpoint inhibitors activate the immune system to combat cancer. In doing so, however, they can cause immune-related adverse events (irAEs), including rheumatic syndromes, such as inflammatory arthritis, polymyalgia rheumatica, and myositis. This article reviews rheumatic irAEs that may be encountered in the general medicine practice and provides guidance to support prompt recognition, referral, and treatment of these patients.

Etiologies of Rheumatoid Arthritis: Update on Mucosal, Genetic, and Cellular Pathogenesis

Purpose of Review

Over the last few years, the scientific community has made significant progress in understanding the etiology of rheumatoid arthritis (RA). In this review, we summarize those key findings and trends.

Recent Findings

New data strongly implicates respiratory exposures, obesity, diet and microbiome, genetics, and their interactions in the etiology of RA. Furthermore, anti-posttranslationally modified protein antibodies (AMPAs) and abnormal glycosylation may be additional biomarkers for RA. Finally, functional genomics techniques implicate loss of certain macrophage populations and proliferation of synovial fibroblasts in RA.

Summary

These findings support the notion that RA originates at mucosal sites, augmented by genetic predisposition, and mediated by certain cell types including macrophages and fibroblasts. Weight loss, physical activity, and diet are additional modifiable factors beyond smoking cessation that can reduce risk of RA. Future epidemiologic and translational studies leveraging multi-omics approaches will help map the precise sequence of events in RA pathogenesis.

Does smoking affect level of seropositivity in RA? A post-HOC global and inter-country analysis of COMORA cohort

To study the association of smoking status and the level of seropositivity in RA patients from COMORA Cohort. A post hoc analysis of COMORA database included 3439 RA patients was performed. Current smokers or recently quitted (< 3 years) were initially compared to those who never smoked or stopped > 3 years (Group I vs. II) regarding their seropositivity status (high positive, low positive and negative) for Rheumatoid Factor (RF) or Anti-citrullinated antibodies (ACPA). A further comparison was made between current smokers (Group III) and never smoked patients (Group IV). Analysis was also done on the individual country level for the 17 countries included in the COMORA study. Out of 3439 RA patients, 705 (20.5%) were smokers (group I), and 2734 (79.5%) were non-smokers (group II). Significantly more patients in group I, 442 (62.7%), had high levels of seropositivity than those in group II, 1556 (56.9%), [P = 0.006, OR 1.27 (95% CI, 1.07-1.5)]. More current smoker patients (group III-286 out of 456 "62.7%") had high levels of seropositivity than never smoked patients (group IV-1236 out of 2191 "56.4%"), with significant difference [P = 0.013, OR 1.3 (95% CI, 1.06-1.6)]. In 11 countries, higher proportions of patients with high level of seropositivity in group I was found, with statistical significance in four countries. Smoking was associated with higher level of seropositivity in patients with RA in this post hoc analysis, both on a global level and in certain individual countries. As smoking is a modifiable risk factor, studying the effects of quitting smoking on level of seropositivity and other disease parameters is warranted.

Human Cytomegalovirus and Autoimmune Diseases: Where Are We?

Human cytomegalovirus (HCMV) is a ubiquitous double-stranded DNA virus belonging to the β-subgroup of the herpesvirus family. After the initial infection, the virus establishes latency in poorly differentiated myeloid precursors from where it can reactivate at later times to cause recurrences. In immunocompetent subjects, primary HCMV infection is usually asymptomatic, while in immunocompromised patients, HCMV infection can lead to severe, life-threatening diseases, whose clinical severity parallels the degree of immunosuppression. The existence of a strict interplay between HCMV and the immune system has led many to hypothesize that HCMV could also be involved in autoimmune diseases (ADs). Indeed, signs of active viral infection were later found in a variety of different ADs, such as rheumatological, neurological, enteric disorders, and metabolic diseases. In addition, HCMV infection has been frequently linked to increased production of autoantibodies, which play a driving role in AD progression, as observed in systemic lupus erythematosus (SLE) patients. Documented mechanisms of HCMV-associated autoimmunity include molecular mimicry, inflammation, and nonspecific B-cell activation. In this review, we summarize the available literature on the various ADs arising from or exacerbating upon HCMV infection, focusing on the potential role of HCMV-mediated immune activation at disease onset.

Female hormonal exposures and risk of rheumatoid arthritis in the French E3N-EPIC cohort study

OBJECTIVE

To assess the relationships between female hormonal exposures and risk of RA in a prospective cohort of French women.

METHODS

E3N (Etude Epidémiologique auprès des femmes de la Mutuelle générale de l'Education Nationale) is an on-going French prospective cohort that included 98 995 women aged 40-65 years in 1990. Every 2-3 years, women completed mailed questionnaires on their lifestyles, reproductive factors and health conditions. Cox proportional hazards regression models were used to determine factors associated with risk of incident RA, with age as the time scale, adjusted for known risk factors of RA, and considering endogenous and exogenous hormonal factors. Hazard ratios (HRs) and 95% CIs were estimated. Effect modification by smoking history was investigated.

RESULTS

A total of 698 incident cases of RA were ascertained among 78 452 women. In multivariable-adjusted Cox regression models, risk of RA was increased with early age at first pregnancy (<22 vs ≥27 years; HR = 1.34; 95% CI 1.0, 1.7) and menopause (≤45 vs ≥53 years; HR = 1.40; 95% CI 1.0, 1.9). For early menopause, the association was of similar magnitude in ever and never smokers, although the association was statistically significant only in ever smokers (HR = 1.54; 95% CI 1.0, 2.3). We found a decreased risk in nulliparous women never exposed to smoking (HR = 0.44; 95% CI 0.2, 0.8). Risk of RA was inversely associated with exposure to progestogen only in perimenopause (>24 vs 0 months; multi-adjusted HR = 0.77; 95% CI 0.6, 0.9).

CONCLUSIONS

These results suggest an effect of both endogenous and exogenous hormonal exposures on RA risk and phenotype that deserves further investigation.

Current Smoking Negatively Affects the Response to Methotrexate in Rheumatoid Arthritis in a Dose-responsive Way, Independently of Concomitant Prednisone Use

OBJECTIVE

Current smoking reduces clinical response to several disease-modifying antirheumatic drugs. It is unknown if this is also the case for prednisone. We aimed to determine whether current smoking affects the clinical response to concomitant prednisone in a methotrexate (MTX)-based treatment strategy.

METHODS

In the CAMERA-II trial (isrctn.com identifier: 70365169), patients with early rheumatoid arthritis (RA) initiated an MTX-based strategy and were randomized to concomitant prednisone (MTX + pred) or placebo (MTX + PBO) for 24 months. Linear mixed modeling was performed with Disease Activity Score assessing 28 joints (DAS28) as the dependent variable, and strategy group and current smoking status as independent variables, correcting for relevant covariates. The interaction between current smoking and strategy was tested to find out whether the effect of current smoking on clinical response was different between the strategy groups with prednisone or PBO.

RESULTS

Current smoking was significantly associated with higher DAS28 over time (mean difference with nonsmokers 0.57 [95% CI 0.22-0.92, P < 0.01]). This association was not different between the strategy groups with prednisone or PBO (P = 0.73). The negative effect of current smoking on DAS28 was dose dependent.

CONCLUSION

Current smoking in patients with early RA significantly reduces the clinical effect of an MTX-based strategy, independent of whether concomitant prednisone is used. This effect is dose dependent.

Rheumatoid Arthritis Pathogenesis, Prediction, and Prevention: An Emerging Paradigm Shift

Rheumatoid arthritis (RA) is currently diagnosed and treated when an individual presents with signs and symptoms of inflammatory arthritis (IA) as well as other features, such as autoantibodies and/or imaging findings, that provide sufficient confidence that the individual has RA-like IA (e.g., meeting established classification criteria) that warrants therapeutic intervention. However, it is now known that there is a stage of seropositive RA during which circulating biomarkers and other factors (e.g., joint symptoms) can be used to predict if and when an individual who does not currently have IA may develop future clinically apparent IA and classifiable RA. Indeed, the discovery of the "pre-RA" stage of seropositive disease has led to the development of several clinical trials in which individuals are studied to identify ways to delay or prevent the onset of clinically apparent IA/RA. This review focuses on several issues pertinent to understanding the prevention of RA. These include discussion of the pathogenesis of pre-RA development, prediction of the likelihood and timing of future classifiable RA, and a review of completed and ongoing clinical trials in RA prevention. Furthermore, this review discusses challenges and opportunities to be addressed to effect a paradigm shift in RA, where in the near future, proactive risk assessment focused on prevention of RA will become a public health strategy in much the same manner as cardiovascular disease is managed today.

The spectrum of association in HLA region with rheumatoid arthritis in a diverse Asian population: evidence from the MyEIRA case-control study

BACKGROUND

Fine-mapping of human leukocyte antigen (HLA) region for rheumatoid arthritis (RA) risk factors has identified several HLA alleles and its corresponding amino acid residues as independent signals (i.e., HLA-A, HLA-B, HLA-DPB1, and HLA-DQA1 genes), in addition to the well-established genetic factor in HLA-DRB1 gene. However, this was mainly performed in the Caucasian and East Asian populations, and data from different Asian regions is less represented. We aimed to evaluate whether there are independent RA risk variants in both anti-citrullinated protein antibody (ACPA)-positive and ACPA-negative RA patients from the multi-ethnic Malaysian population, using the fine-mapping of HLA region strategy.

METHODS

We imputed the classical HLA alleles, amino acids, and haplotypes using the Immunochip genotyping data of 1260 RA cases (i.e., 530 Malays, 259 Chinese, 412 Indians, and 59 mixed ethnicities) and 1571 controls (i.e., 981 Malays, 205 Chinese, 297 Indians, and 87 mixed ethnicities) from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) population-based case-control study. Stepwise logistic regression was performed to identify the independent genetic risk factors for RA within the HLA region.

RESULTS

We confirmed that the HLA-DRB1 amino acid at position 11 with valine residue conferred the strongest risk effect for ACPA-positive RA (OR = 4.26, 95% CI = 3.30-5.49, P_GWAS = 7.22 × 10^-29) in the Malays. Our study also revealed that HLA-DRB1 amino acid at position 96 with histidine residue was negatively associated with the risk of developing ACPA-positive RA in the Indians (OR = 0.48, 95% CI = 0.37-0.62, P_GWAS = 2.58 × 10^-08). Interestingly, we observed that HLA-DQB1*03:02 allele was inversely related to the risk of developing ACPA-positive RA in the Malays (OR = 0.17, 95% CI = 0.09-0.30, P_GWAS = 1.60 × 10^-09). No association was observed between the HLA variants and risk of developing ACPA-negative RA in any of the three major ethnic groups in Malaysia.

CONCLUSIONS

Our results demonstrate that the RA-associated genetic factors in the multi-ethnic Malaysian population are similar to those in the Caucasian population, despite significant differences in the genetic architecture of HLA region across populations. A novel and distinct independent association between the HLA-DQB1*03:02 allele and ACPA-positive RA was observed in the Malays. In common with the Caucasian population, there is little risk from HLA region for ACPA-negative RA.

Lifestyle factors associated with incidence of rheumatoid arthritis in US adults: analysis of National Health and Nutrition Examination Survey database and meta-analysis

OBJECTIVE

To quantify rheumatoid arthritis (RA) cases attributable to selected non-genetic risk factors.

DESIGN

National Health and Nutrition Examination Survey (NHANES) and meta-analysis.

PARTICIPANTS

US adults.

DATA SOURCES

The prevalence of exposure was obtained from NHANES. Weighted analysis was performed to account for the complex sampling design in NHANES. PubMed and Web of Science up to 31 March 2019 were searched to identify epidemiological studies reported the association between non-genetic risk factors and RA in US adults. Relative risk (RR) value and the corresponding CI were pooled by meta-analysis to evaluate the associations between modifiable risk factors and RA. Population attributable fraction (PAF) was calculated based on the prevalence and RR data.

RESULTS

The weighted percentages of former smokers, current smokers and overweight or obese people were 24.84%, 23.93% and 63.97%, and the average alcohol consumption was 51.34 g/week. In the meta-analysis, we found that former smokers (RR 1.22, 95% CI 1.10 to 1.36) and current smokers (RR 1.47, 95% CI 1.29 to 1.68) had higher risks of RA. Overweight and obese individuals had 1.27-fold (95% CI 1.09 to 1.48) increased risk of RA. Each per 50 g/week increment of alcohol consumption was associated with 8% (95% CI 0% to 16%) reduction in the risk of RA. Therefore, PAF value of smoking was 14.00% (95% CI 8.13% to 23.33%). Excess body mass index (BMI) was found to account for 14.73% (95% CI 5.45% to 23.50%) of RA incidence. The fraction of RA risk attributed by low alcohol intake was 8.21% (95% CI 0.31% to 16.39%). Collectively, we found that 32.69% (95% CI 13.41% to 50.96%) of RA cases were attributable to smoking, overweight or obesity and low alcohol drinking.

CONCLUSION

Nearly 33% of RA incidence was attributed to smoking, excess BMI and low alcohol drinking in USA. Our findings could provide a basis for developing guidelines of RA prevention and control in USA.

The Role of Nutritional Factors and Intestinal Microbiota in Rheumatoid Arthritis Development

Evidence about the role of nutritional factors and microbiota in autoimmune diseases, and in rheumatoid arthritis (RA) in particular, has grown in recent years, however many controversies remain. The aim of this review is to summarize the role of nutrition and of the intestinal microbiota in the development of RA. We will focus on selected dietary patterns, individual foods and beverages that have been most consistently associated with RA or with the occurrence of systemic autoimmunity associated with RA. We will also review the evidence for a role of the intestinal microbiota in RA development. We propose that diet and digestive microbiota should be considered together in research, as they interact and may both be the target for future preventive interventions in RA.

Beyond the joints, the extra-articular manifestations in rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory disease typically affecting the joints, but the systemic inflammatory process may involve other tissues and organs. Many extra-articular manifestations are recognized, which are related to worse long outcomes. Rheumatoid nodules are the most common extra-articular feature, found in about 30% of patients. Secondary Sjögren's syndrome and pulmonary manifestations are observed in almost 10% of patients, also in the early disease. Active RA with high disease activity has been associated with an increased risk of such features. Male gender, smoking habit, severe joint disease, worse function, high pro-inflammatory markers levels, high titer of rheumatoid factor, and HLA-related shared epitope have been reported as clinical predictors of occurrence of these rheumatoid complications. In addition, there is a little evidence deriving from randomized controlled trials in this field, thus the therapeutic strategy is mainly empiric and based on small case series and retrospective studies. However, considering that these extra-articular manifestations are usually related to the more active and severe RA, an aggressive therapeutic strategy is usually employed in view of the poor outcomes of these patients. The extra-articular features of RA remain, despite the improvement of joint damage, a major diagnostic and therapeutic challenge, since these are associated with a poor prognosis and need to be early recognized and promptly managed.

Influence factors of extra-articular manifestations in rheumatoid arthritis

Background and objective

Extra-articular manifestations (EAMs) are serious outcomes or complications of rheumatoid arthritis (RA) with increasing mortality and morbidity. The purpose was to explore the factors influencing EAMs, tissue-specific/systemic EAMs, and the concurrence of several EAMs.

Patients and methods

In total, 519 inpatients with RA were enrolled. The clinical characteristics, laboratory parameters, and medications of RA patients and the details of EAMs were recorded carefully. Differences between groups were examined by a Chi-square test, independent samples t test, one-way analysis of variance, Mann-Whitney U test, and Kruskal-Wallis H test. Binary and ordinal logistic regression analyses were performed to determine the relationship between influential factors and EAMs, tissue-specific/systemic EAMs, and the concurrence of several EAMs.

Results

The morbidity of EAMs was 44.70%. Male sex, age, and traditional Chinese medicine (TCM) were independent influential factors of EAMs, and a number of statistically significant influence factors were found in the multivariate analysis of tissue-specific/systemic EAMs. Finally, age, CRP levels, number of RA-affected types of joints, and TCM were the factors that independently influenced the concurrence of several EAMs.

Conclusion

Influential factors identified in this study could be recommended in clinical work, which is hopeful to decrease the morbidity and mortality of EAMs in RA.

Persistent inflammatory and non-inflammatory mechanisms in refractory rheumatoid arthritis

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

Respiratory Diseases as Risk Factors for Seropositive and Seronegative Rheumatoid Arthritis and in Relation to Smoking

OBJECTIVE

The link and interplay between different airway exposures and rheumatoid arthritis (RA) risk are unclear. This study was undertaken to determine whether respiratory disease is associated with development of RA, and specifically to examine this relationship by RA serostatus and smoking exposure.

METHODS

Using data from the Epidemiological Investigation of Rheumatoid Arthritis study, this analysis included 1,631 incident RA cases and 3,283 matched controls recruited from 2006 to 2016. Linking these individuals to the National Patient Register provided information on past acute or chronic, upper or lower respiratory disease diagnoses. For each disease group, we estimated adjusted odds ratios (OR_adj ) with 95% confidence intervals (95% CI) for RA, using logistic regression models adjusted for age, sex, residential area, body mass index, and education both overall and stratified by anti-citrullinated protein antibody (ACPA)/rheumatoid factor (RF) status and by smoking status.

RESULTS

Respiratory disease diagnoses were associated with risk of RA, with an OR_adj of 1.2 for acute upper respiratory disease (95% CI 0.8-1.7), 1.4 for chronic upper respiratory disease (95% CI 1.1-1.9), 2.4 for acute lower respiratory disease (95% CI 1.5-3.6), and 1.6 for chronic lower respiratory disease (95% CI 1.5-3.6). These associations were present irrespective of RF or ACPA status, though the association was somewhat stronger for ACPA/RF-positive than ACPA/RF-negative RA. The association between any respiratory disease and RA was stronger for nonsmokers (OR_adj 2.1 [95% CI 1.5-2.9]) than for smokers (OR_adj 1.2 [95% CI 0.9-1.5]).

CONCLUSION

Respiratory diseases increase the risk for both seropositive and seronegative RA, but only among nonsmokers. These findings raise the hypothesis that smoking and airway disease are associated with RA development through partly different mechanisms.

Presence of salivary IgA anti-citrullinated protein antibodies associate with higher disease activity in patients with rheumatoid arthritis

Background

Circulating IgA anti-citrullinated protein antibodies (ACPA) associate with more active disease, but a previous study implied that salivary IgA ACPA is related to a less severe disease. Therefore, we aimed to characterize the IgA ACPA response in the saliva and serum in relation to clinical picture and risk factors among patients with rheumatoid arthritis (RA).

Methods

RA patients (n = 196) and healthy blood donors (n = 101), included in the cross-sectional study “Secretory ACPA in Rheumatoid Arthritis” (SARA), were analyzed for ACPA of IgA isotype, and for subclasses IgA1 and IgA2 ACPA in paired saliva and serum samples using modified enzyme-linked immunosorbent assays (ELISA) targeting reactivity to a cyclic citrullinated peptide (anti-CCP). Cutoff levels for positive tests were set at the 99th percentile for blood donors. Antibody levels were related to clinical characteristics, radiographic damage, smoking habits, and carriage of HLA-DRB1/shared epitope (SE).

Results

IgA ACPA in the saliva was found in 12% of RA patients, IgA1 occurred in 10%, and IgA2 in 9%. In serum, IgA ACPA was found in 45% of the patients, IgA1 in 44%, and IgA2 in 39%. Levels of IgA ACPA in the saliva correlated significantly with serum levels of IgA (r = 0.455). The presence of salivary IgA ACPA was associated with a higher erythrocyte sedimentation rate (ESR), 28-joint disease activity score, tender joint count, and patient global assessment at the time of sampling. None of the antibodies was associated with smoking, SE, or radiographic damage.

Conclusion

Salivary IgA ACPAs were detected in a subset of RA patients in association with higher disease activity. This suggests that mucosal ACPA responses in the oral cavity may contribute to disease-promoting processes in RA.

Revisiting B cell tolerance and autoantibodies in seropositive and seronegative autoimmune rheumatic disease (AIRD)

Autoimmune rheumatic diseases (AIRD) are categorized seropositive or seronegative, dependent upon the presence or absence of specific autoreactive antibodies, including rheumatoid factor and anti-citrullinated protein antibodies. Autoantibody-based diagnostics have proved helpful in patient care, not only for diagnosis but also for monitoring of disease activity and prediction of therapy responsiveness. Recent work demonstrates that AIRD patients develop autoantibodies beyond those contained in the original categorization. In this study we discuss key mechanisms that underlie autoantibody development in AIRD: defects in early B cell development, genetic variants involved in regulating B cell and T cell tolerance, environmental triggers and antigen modification. We describe how autoantibodies can directly contribute to AIRD pathogenesis through innate and adaptive immune mechanisms, eventually culminating in systemic inflammation and localized tissue damage. We conclude by discussing recent insights that suggest distinct AIRD have incorrectly been denominated seronegative.

The global prevalence of rheumatoid arthritis: a meta-analysis based on a systematic review

The objective is to determine the global population prevalence of rheumatoid arthritis (RA) based on population-based studies and assess factors that influence RA prevalence estimates. Four electronic databases were searched (ProQuest Central, MEDLINE, Web of Science, and EMBASE) for peer-reviewed English publications that report prevalence estimates of RA from 1980 and 2019. We included case-control studies, cross-sectional studies, and prospective or retrospective cohort studies in our search strategy. A random-effect meta-analysis model was used to produce the pooled prevalence estimates. The potential between-study heterogeneity was identified using sensitivity analysis, sub-group and meta-regression analyses. A total of 67 studies were included in the meta-analysis, containing 742,246 RA patients and 211,592,925 healthy controls in the study period. The global RA prevalence estimate was 0.46% (95% confidence interval [CI] 0.39-0.54; I² = 99.9%) with a 95% prediction interval (0.06-1.27). The RA point-prevalence was 0.45% (95% CI 0.38-0.53%) between 1986 and 2014, while the pooled period-prevalence was 0.46% (95% CI 0.36% and 0.57%) from 1955 to 2015. The highest RA pooled prevalence (0.69%; 95% CI 0.47-0.95) was derived from linked data source studies. Based on meta-regression, the factors that explain the studies' heterogeneity of RA prevalence, including geographical location, the risk bias assessment of studies and sample size. The global prevalence of RA between 1980 and 2019 was 460 per 100,000 population, with variations due to geographical location and study methodology. Linked data are the preferred method to estimate RA population prevalence as they provide the best case ascertainment.

Mini-Review: Human Microbiome and Rheumatic Diseases

Rheumatoid arthritis and spondyloarthropathy are the most common inflammatory rheumatic diseases. As the human microbiome is involved in the immune homeostasis, it has the potential to be a key factor in the development of autoimmune diseases and rheumatic diseases. In this article, we review the role of various human microbiota on the pathogenesis of rheumatic diseases, focusing on spondylarthritis and rheumatoid arthritis.