Associations of Smoking and Age With Inflammatory Joint Signs Among Unaffected First-Degree Relatives of Rheumatoid Arthritis Patients: Results From Studies of the Etiology of Rheumatoid Arthritis

Associations of the MUC5B promoter variant with timing of interstitial lung disease and rheumatoid arthritis onset

OBJECTIVES

To investigate the associations of the common MUC5B promoter variant with timing of RA-associated interstitial lung disease (RA-ILD) and RA onset.

METHODS

We identified patients with RA meeting 2010 ACR/EULAR criteria and available genotype information in the Mass General Brigham Biobank, a multihospital biospecimen and clinical data collection research study. We determined RA-ILD presence by reviewing all RA patients who had CT imaging, lung biopsy or autopsy results. We determined the dates of RA and RA-ILD diagnoses by manual records review. We examined the associations of the MUC5B promoter variant (G>T at rs35705950) with RA-ILD, RA-ILD occurring before or within 2 years of RA diagnosis and RA diagnosis at age >55 years. We used multivariable logistic regression to estimate odds ratios (ORs) for each outcome by MUC5B promoter variant status, adjusting for potential confounders including genetic ancestry and smoking.

RESULTS

We identified 1005 RA patients with available genotype data for rs35705950 (mean age 45 years, 79% female, 81% European ancestry). The MUC5B promoter variant was present in 155 (15.4%) and was associated with RA-ILD [multivariable OR 3.34 (95% CI 1.97, 5.60)], RA-ILD before or within 2 years of RA diagnosis [OR 4.01 (95% CI 1.78, 8.80)] and RA onset after age 55 years [OR 1.52 (95% CI 1.08, 2.12)].

CONCLUSIONS

The common MUC5B promoter variant was associated with RA-ILD onset earlier in the RA disease course and older age of RA onset. These findings suggest that the MUC5B promoter variant may impact RA-ILD risk early in the RA disease course, particularly in patients with older-onset RA.

A Roadmap for Investigating Preclinical Autoimmunity Using Patient-Oriented and Epidemiologic Study Designs: Example of Rheumatoid Arthritis

Background & Aims

Rheumatoid arthritis (RA) is a prototypic autoimmune disease causing inflammatory polyarthritis that affects nearly 1% of the population. RA can lead to joint destruction and disability along with increased morbidity and mortality. Similar to other autoimmune diseases, RA has distinct preclinical phases corresponding to genetic risk, lifestyle risk factors, autoantibody development, and non-specific symptoms prior to clinical diagnosis. This narrative review will detail observational studies for RA risk and clinical trials for RA prevention as a roadmap to investigating preclinical autoimmunity that could be applied to other diseases.

Methods

In this narrative review, we summarized previous and ongoing research studies investigating RA risk and prevention, categorizing them related to their design and preclinical phases.

Results

We detailed the following types of studies investigating RA risk and prevention: retrospective population-based and administrative datasets; prospective studies (case-control and cohort; some enrolling based on genetics, first-degree relative status, elevated biomarkers, or early symptoms/arthritis); and randomized clinical trials. These correspond to all preclinical RA phases (genetic, lifestyle, autoimmunity, early signs/symptoms). Previous and ongoing randomized controlled trials have enrolled individuals at very elevated risk for RA based on biomarkers, symptoms, imaging abnormalities, or early signs/symptoms.

Conclusion

We detailed the rich variety of study designs that is necessary to investigate distinct preclinical phases of an autoimmune disease such as RA. However, further progress is needed to fully elucidate the pathogenesis of RA that may ultimately lead to prevention or delay of disease onset.

Potential Target Analysis of Triptolide Based on Transcriptome-Wide m6A Methylome in Rheumatoid Arthritis

Triptolide (TP), a major active component of the herb Tripterygium wilfordii Hook F (TwHF), has been shown to exert therapeutic potential against rheumatoid arthritis (RA). However, its molecular mechanism of action has not been fully elucidated. This study aimed to analyze the potential target of TP based on the discovery of differentially methylated and expressed genes (DMEGs) in RA using methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq). Five RA samples and ten control samples were obtained from China-Japan Friendship Hospital. The various levels of m⁶A methylation and genes expressed in the RA and control groups were compared by MeRIP-seq and RNA-seq. Bioinformatics explorations were also performed to explore the enriched biological roles and paths of the differentially expressed m⁶A methylation and genes. Molecular networks between TP target proteins and DMEGs were performed using Ingenuity Pathway Analysis (IPA) software. Potential target of TP was determined with Gene Expression Omnibus (GEO) database mining, molecular docking, and in vitro experiment validation. In total, 583 dysregulated m⁶A peaks, of which 295 were greatly upregulated and 288 were greatly downregulated, were identified. Similarly, 1,570 differentially expressed genes were identified by RNA-seq, including 539 upregulated and 1,031 downregulated genes. According to the deeper joint exploration, the m⁶A methylation and mRNA expression degrees of 35 genes varied greatly. Molecular networks between TP target proteins and DMEGs were constructed, and the results revealed that tubulin beta-2A chain (TUBB2A), insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3), cytoplasmic dynein 1 intermediate chain 1 (DYNC1I1), and FOS-like 1 (FOSL1) were the most relevant genes that correlated with the target proteins of TP. The results of the GEO database showed that the gene expression of IGF2BP3 was increased in RA synovial tissue and consistent with the trend of our sequencing results of RA PBMCs. Molecular docking and in vitro experiment suggested that TP and IGF2BP3 had a high binding affinity and TP could decrease the mRNA expression of IGF2BP3 in PBMCs and MH7A.This research established a transcriptional map of m⁶A in RA PBMCs and displayed the hidden association between RNA methylation alterations and associated genes in RA. IGF2BP3 might be a potential therapeutic target of TP during RA treatment.

Evaluating associations of joint swelling, joint stiffness and joint pain with physical activity in first-degree relatives of patients with rheumatoid arthritis: Studies of the Aetiology of Rheumatoid Arthritis (SERA), a prospective cohort study

OBJECTIVE

Physical activity (PA) in preclinical rheumatoid arthritis (RA) is associated with lower RA risk and disease severity. As joint signs and symptoms of inflammatory arthritis serve as a barrier to PA in RA, it is important to consider whether they affect PA in the time prior to RA. Therefore, we investigated whether joint swelling, stiffness or pain were associated with PA in first-degree relatives (FDRs) of patients with RA, a population at higher risk for future RA.

DESIGN

Prospective study design.

SETTING

We recruited FDRs of patients with RA from academic centres, Veterans' hospitals and rheumatology clinics or through responses to advertising from six sites across the USA.

PARTICIPANTS

We evaluated associations of joint stiffness, joint swelling and joint pain with PA time in 268 FDRs with ≥2 visits over an average 1.2 years. Clinicians confirmed joint swelling. Participants self-reported joint stiffness and/or pain.

PRIMARY OUTCOME MEASURES

PA during a typical 24-hour day was quantified via questionnaire, weighted to reflect metabolic expenditure, where 24 hours was the minimum PA time. Linear mixed models evaluated associations between symptoms and change in PA over time, adjusting for age, sex, race, body mass index, smoking and RA-related autoantibodies.

RESULTS

Average weighted PA time was 37±7 hours. In the cross-sectional analysis, PA time was 1.3±0.9 hours higher in FDRs reporting joint pain (p=0.15); and 0.8±1.6 and 0.4±1 hours lower in FDRs with joint swelling (p=0.60) and stiffness (p=0.69), respectively. Longitudinally, adjusting for baseline PA time, baseline symptoms were not significantly associated with changes in PA time. However, on average over time, joint stiffness and pain were associated with lower PA time (p_interaction=0.0002, p_interaction=0.002), and joint swelling was associated with higher PA time (p_interaction <0.0001).

CONCLUSION

Baseline symptoms did not predict future PA time, but on average over time, joint symptoms influenced PA time.

Symptoms in first-degree relatives of patients with rheumatoid arthritis: evaluation of cross-sectional data from the symptoms in persons at risk of rheumatoid arthritis (SPARRA) questionnaire in the PRe-clinical EValuation of Novel Targets in RA (PREVeNT-RA) Cohort

BACKGROUND

First-degree relatives (FDRs) of people with rheumatoid arthritis (RA) have a fourfold increased risk of developing RA. The Symptoms in Persons At Risk of Rheumatoid Arthritis (SPARRA) questionnaire was developed to document symptoms in persons at risk of RA. The aims of this study were (1) to describe symptoms in a cohort of FDRs of patients with RA overall and stratified by seropositivity and elevated CRP and (2) to determine if patient characteristics were associated with symptoms suggestive of RA.

METHODS

A cross-sectional study of FDRs of patients with RA, in the PREVeNT-RA study, who completed a study questionnaire, provided a blood sample measured for rheumatoid factor, anti-CCP and CRP and completed the SPARRA questionnaire. Moderate/severe symptoms and symmetrical, small and large joint pain were identified and described. Symptoms associated with both seropositivity and elevated CRP were considered suggestive of RA. Logistic regression was used to determine if symptoms suggestive of RA were associated with patient characteristics.

RESULTS

Eight hundred seventy participants provided all data, 43 (5%) were seropositive and 122 (14%) had elevated CRP. The most frequently reported symptoms were sleep disturbances (20.3%) and joint pain (17.9%). Symmetrical and small joint pain were 11.3% and 12.8% higher, respectively, in those who were seropositive and 11.5% and 10.7% higher in those with elevated CRP. In the logistic regression model, seropositivity, older age and feeling depressed were associated with increased odds of small and symmetrical joint pain.

CONCLUSIONS

This is the first time the SPARRA questionnaire has been applied in FDRs of patients with RA and has demonstrated that the presence of symmetrical and small joint pain in this group may be useful in identifying people at higher risk of developing RA.

Determining in which pre-arthritis stage HLA-shared epitope alleles and smoking exert their effect on the development of rheumatoid arthritis

OBJECTIVES

The human leukocyte antigen-shared epitope (HLA-SE) alleles and smoking are the most prominent genetic and environmental risk factors for rheumatoid arthritis (RA). However, at which pre-arthritis stage (asymptomatic/symptomatic) they exert their effect is unknown. We aimed to determine whether HLA-SE and smoking are involved in the onset of autoantibody positivity, symptoms (clinically suspect arthralgia (CSA)) and/or progression to clinical arthritis.

METHODS

We performed meta-analyses on results from the literature on associations of HLA-SE and smoking with anti-citrullinated protein antibodies (ACPAs) in the asymptomatic population. Next, we studied associations of HLA-SE and smoking with autoantibody positivity at CSA onset and with progression to clinical inflammatory arthritis (IA) during follow-up. Associations in ACPA-positive patients with CSA were validated in meta-analyses with other arthralgia cohorts. Analyses were repeated for rheumatoid factor (RF), anti-carbamylated protein antibodies (anti-CarP) and anti-acetylated protein antibodies (AAPA).

RESULTS

Meta-analyses showed that HLA-SE is not associated with ACPA positivity in the asymptomatic population (OR 1.06 (95% CI:0.69 to 1.64)), whereas smoking was associated (OR 1.37 (95% CI: 1.15 to 1.63)). At CSA onset, both HLA-SE and smoking associated with ACPA positivity (OR 2.08 (95% CI: 1.24 to 3.49), OR 2.41 (95% CI: 1.31 to 4.43)). During follow-up, HLA-SE associated with IA development (HR 1.86 (95% CI: 1.23 to 2.82)), in contrast to smoking. This was confirmed in meta-analyses in ACPA-positive arthralgia (HR 1.52 (95% CI: 1.08 to 2.15)). HLA-SE and smoking were not associated with RF, anti-CarP or AAPA-positivity at CSA onset. Longitudinally, AAPA associated with IA development independent from ACPA and RF (HR 1.79 (95% CI: 1.02 to 3.16)), anti-CarP did not.

CONCLUSIONS

HLA-SE and smoking act at different stages: smoking confers risk for ACPA and symptom development, whereas HLA-SE mediates symptom and IA development. These data enhance the understanding of the timing of the key risk factors in the development of RA.

Risk Factors for Developing Rheumatoid Arthritis in Patients With Undifferentiated Arthritis and Inflammatory Arthralgia

Currently, there is an increasing interest in treating patients at risk of rheumatoid arthritis (RA) to prevent the development of this chronic disease. In this sense, research has focused attention on the early identification of predictive factors of this disease. Autoantibodies and markers of systemic inflammation can be present before clinical arthritis and RA development. So, the phase of inflammatory arthralgia preceding clinical arthritis is an important part of the window of opportunity and, starting treatment might prevent progression to chronic arthritis. Additionally, the early diagnosis and treatment initiation, in patients with inflammatory arthritis at risk of persistence and/or erosive progression, are fundamental because may allow optimal clinical responses, better chances of achieving sustained remission, preventing irreversible organ damage and optimizing long-term outcomes. This review aims to give an overview of clinical risk factors for developing RA, both in suspected arthralgia and in undifferentiated arthritis. Besides taking into consideration the role of serological markers (immunological and acute phase reactants) and clinical features assessed at consultation such as: articular affection and patient's clinical perception. Other features as sociodemographic and environmental factors (lifestyle habits, microbiota, periodontal disease among others), have been included in this revision to give an insight on strategies to prevent development of RA and/or to treat it in early stages.

Rethink About the Role of Rheumatoid Factor and Anti-citrullinated Protein Antibody in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by joint inflammation and extra-articular manifestations. Many questions in the pathogenesis, clinical manifestation, and disease spectrum are answered after the discovery of the first autoantibody namely rheumatoid factor (RF). The finding of the second autoantibody named anti-citrullinated protein antibody (ACPA), which unearths the importance of protein citrullination process. It further provides the insight how immune cells and complement interact to perpetuate the inflammatory response. These two autoantibodies pave the way for our better understanding of RA. This review article focuses on the history, pathophysiology, and clinical association of these two autoantibodies in RA.

Factors associated with progression to inflammatory arthritis in first-degree relatives of individuals with RA following autoantibody positive screening in a non-clinical setting

OBJECTIVES

Little is known about the likelihood of developing inflammatory arthritis (IA) in individuals who screen autoantibody positive (aAb+) in a non-clinical research setting.

METHODS

We screened for serum cyclic citrullinated peptide antibody (anti-CCP) and rheumatoid factor isotype aAbs in subjects who were at increased risk for rheumatoid arthritis (RA) because they are a first-degree relative of an individual with classified RA (n=1780). We evaluated combinations of aAbs and high titre aAbs, as defined by 2-times (2 x) the standard cut-off and an optimal cut-off, as predictors of our two outcomes, aAb+ persistence and incident IA.

RESULTS

304 subjects (17.1%) tested aAb+; of those, 131 were IA-free and had at least one follow-up visit. Sixty-four per cent of these tested aAb+ again on their next visit. Anti-CCP+ at levels ≥2 x the standard cut-off was associated with 13-fold higher likelihood of aAb +persistence. During a median of 4.4 years (IQR: 2.2-7.2), 20 subjects (15.3%) developed IA. Among subjects that screened anti-CCP+ at ≥ 2 x or ≥an optimal cut-off, 32% and 26% had developed IA within 5 years, respectively. Both anti-CCP cut-offs conferred an approximate fourfold increased risk of future IA (HR 4.09 and HR 3.95, p<0.01).

CONCLUSIONS

These findings support that aAb screening in a non-clinical setting can identify RA-related aAb+ individuals, as well as levels and combinations of aAbs that are associated with higher risk for future IA. Monitoring for the development of IA in aAb+ individuals and similar aAb testing approaches in at-risk populations may identify candidates for prevention studies in RA.

Family History of Rheumatic, Autoimmune, and Nonautoimmune Diseases and Risk of Rheumatoid Arthritis

OBJECTIVE

Since comorbidities such as autoimmune diseases may be associated with rheumatoid arthritis (RA) risk, we hypothesized that a family history of these other conditions might also predict RA. Therefore, we aimed to determine the association between family history of 79 comorbidities and RA.

METHODS

This case-control study identified 821 cases of RA in the Mayo Clinic Biobank (positive predictive value 95%) and matched 3 controls to each case based on age, sex, recruitment year, and location. Patients self reported family history and characteristics (adjusted). Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) for RA risk according to the presence of family history for each comorbidity, adjusted for body mass index, race, and smoking.

RESULTS

Family history of several conditions was associated with developing RA, including rheumatic autoimmune diseases (ORadj 1.89 [95% CI 1.41-2.52]), pulmonary fibrosis (ORadj 2.12 [95% CI 1.16-3.80]), inflammatory bowel disease (ORadj 1.45 [95% CI 1.05-1.98]), hyper/hypothyroidism (ORadj 1.34 [95% CI 1.10-1.63]), and obstructive sleep apnea (ORadj 1.28 [95% CI 1.05-1.55]). Parkinson's disease and type 2 diabetes mellitus were associated with a statistically decreased risk of RA that did not reach the prespecified significance threshold of P < 0.01 (ORadj 0.70 [95% CI 0.49-0.98] and ORadj 0.81 [95% CI 0.67-0.97], respectively). Analyses among 143 cases of incident RA were similar and also suggested an association with a family history of autism (OR 10.5 [95% CI 2.51-71.3]).

CONCLUSION

Family history of several autoimmune and nonautoimmune comorbidities was associated with increased risk of RA, providing an opportunity to identify novel populations at risk for RA.

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.

Reinterpreting Evidence of Rheumatoid Arthritis-Associated Interstitial Lung Disease to Understand Etiology

Interstitial Lung Disease (ILD) is a well-known complication of rheumatoid arthritis (RA) which often results in significant morbidity and mortality. It is often diagnosed late in the disease process via descriptive criteria. Multiple subtypes of RA-ILD exist as defined by chest CT and histopathology. In the absence of formal natural history studies and definitive diagnostics, a conventional dogma has emerged that there are two major subtypes of RA-ILD (nonspecific interstitial pneumonia (NSIP) and Usual Interstitial Pneumonia (UIP)). These subtypes are based on clinical experience and correlation studies. However, recent animal model data are incongruous with established paradigms of RA-ILD and beg reassessment of the clinical evidence in order to better understand etiology, pathogenesis, prognosis, and response to therapy. To this end, here we: 1) review the literature on epidemiology, radiology, histopathology and clinical outcomes of the various RAILD subtypes, existing animal models, and current theories on RA-ILD pathogenesis; 2) highlight the major gaps in our knowledge; and 3) propose future research to test an emerging theory of RAILD that posits initial rheumatic lung inflammation in the form of NSIP-like pathology transforms mesenchymal cells to derive chimeric disease, and subsequently develops into frank UIP-like fibrosis in some RA patients. Elucidation of the pathogenesis of RA-ILD is critical for the development of effective interventions for RA-ILD.

Impact of Cyclic Citrullinated Peptide Antibody Level on Progression to Rheumatoid Arthritis in Clinically Tested Cyclic Citrullinated Peptide Antibody-Positive Patients Without Rheumatoid Arthritis

OBJECTIVE

To investigate the risk of progression to rheumatoid arthritis (RA) in patients who were cyclic citrullinated peptide (CCP) antibody positive without RA at initial presentation.

METHODS

We performed a retrospective cohort study of CCP+ individuals seen at a US tertiary care system between 2009 and 2018 who were without RA or other systemic rheumatic disease by medical record review at the time of CCP antibody positivity. Progression to classifiable RA was determined through medical record review. We investigated the risk of progression to RA overall and stratified by CCP antibody level (low: >1 to 2× the upper limit of normal [ULN]; medium: >2 to 3× ULN; high: >3× ULN). Multivariable Cox regression estimated the hazard ratio (HR) and 95% confidence interval (95% CI) for RA by CCP antibody level.

RESULTS

We identified 340 CCP+ patients who were without RA or other rheumatic disease at baseline. During 1,047 person-years of follow-up, 73 patients (21.5%) developed RA. The risk of progression to RA increased with CCP antibody level, with 46.0% (95% CI 34.7-55.3) of patients with high-level CCP antibodies progressing to RA by 5 years. Compared to low CCP antibody level, medium (HR 3.00 [95% CI 1.32-6.81]) and high (HR 4.83 [95% CI 2.51-9.31]) CCP antibody levels were strongly associated with progression to RA, adjusting for age, sex, body mass index, smoking, family history of RA, and rheumatoid factor level.

CONCLUSION

Among CCP+ patients without RA, the risk for progression to RA increased substantially with increasing CCP antibody level. This study provides further support for close monitoring for development of RA among CCP+ patients and identifying strategies to mitigate this risk.

Quercetin suppresses migration and invasion by targeting miR-146a/GATA6 axis in fibroblast-like synoviocytes of rheumatoid arthritis

Background: Rheumatoid arthritis (RA) is a systematic autoimmune disease which may lead to joint dysfunction and disability. Aberrant migration and invasion of fibroblast-like synoviocytes (FLSs) is one of the most predominant etiopathogenesis of RA. Quercetin is a bioflavonoid which is implicated in the development of RA, yet its role in regulating the migration and invasion of FLSs is still elusive. The aim of this study is to investigate the impact of quercetin treatment on migration and invasion of FLSs and the underlying mechanism.Methods: Capacity of migration and invasion of FLSs were assessed using transwell assay. Immunofluorescence assay was used to determine the expression of F-actin. The RNA levels of miR-146a and GATA transcription factor 6 (GATA6) were measured using quantitative real-time PCR. Western blot was used to examine the protein level of GATA6. The correlation between miR-146a and GATA6 was validated using luciferase reporter assay.Results: Transwell assay revealed that the migration and invasion of FLSs were significantly inhibited after quercetin treatment, which was also proved by decreased expression of F-actin. The RNA level of miR-146a was decreased in RA tissues and was negatively related to the expression of GATA transcription factor 6 (GATA6). Quercetin treatment elevated the RNA level of miR-146a, but suppressed the expression of GATA6 in FLSs. Further luciferase reporter assay validated that GATA6 is a downstream target of miR-146a. Besides, miR-146a inhibited the migration and invasion of FLSs, and further GATA6 over-expression abrogated the miR-146a-induced inhibition. In addition, specific anti-miR-146a inhibitor abolished quercetin-mediated suppression of migration and invasion of FLSs.Conclusion: Our study suggested that quercetin suppresses the migration and invasion of FLSs via regulating the miR-146a/GATA6 axis.

Precision medicine in the care of rheumatoid arthritis: Focus on prediction and prevention of future clinically-apparent disease

There is an emerging understanding that an individual's risk for future rheumatoid arthritis (RA) can be determined using a combination of factors while they are still in a state where clinically-apparent inflammatory arthritis (IA) is not yet present. Indeed, this concept has underpinned several completed and ongoing prevention trials in RA. Importantly, risk factors can be divided into modifiable (e.g. smoking, exercise, dental care and diet) and non-modifiable factors (e.g. genetics, sex, age). In addition, there are now several biomarkers including autoantibodies, inflammatory markers and imaging techniques that are highly predictive of future clinically-apparent IA/RA. Although none of the prevention studies have yet provided major breakthroughs, several of them have provided valuable insights that can help to improve the design of future clinical trials and enable RA prevention. In aggregate, these findings suggest that the most accurate disease prediction models will require the combination of demographic and clinical information, biomarkers and potentially medical imaging data to identify individuals for intervention. This review summarizes some of the key aspects around precision medicine in RA with special focus on disease prediction and prevention.

Is the prevention of rheumatoid arthritis possible?

Preclinical phases of rheumatoid arthritis (RA) have been described, genetic and environmental risk factors for RA development have been identified, and several biomarkers of RA have been detected long before the clinical onset of the disease; all of which have opened the possibility for preventive interventions. Several studies are currently exploring pharmacological and non-pharmacological interventions to prevent the development of RA. We will review the evidence for prevention of RA and discuss key challenges for preventive interventions, including identification of the adequate target population, the risks of applying potentially harmful and expensive therapies to asymptomatic at-risk individuals, and the importance of taking into account the preferences of individuals at risk regarding preventive treatment options.

Epigenetics in rheumatoid arthritis; fibroblast-like synoviocytes as an emerging paradigm in the pathogenesis of the disease

Rheumatoid arthritis (RA) is characterized by immune dysfunctions and chronic inflammation that mainly affects diarthrodial joints. Genetics has long been surveyed in searching for the etiopathogenesis of the disease and partially clarified the conundrums within this context. Epigenetic alterations, such as DNA methylation, histone modifications, and noncoding RNAs, which have been considered to be involved in RA pathogenesis, likely explain the nongenetic risk factors. Epigenetic modifications may influence RA through fibroblast-like synoviocytes (FLSs). It has been shown that FLSs play an essential role in the onset and exacerbation of RA, and therefore, they may illustrate some aspects of RA pathogenesis. These cells exhibit a unique DNA methylation profile in the early stage of the disease that changes with disease progression. Histone acetylation profile in RA FLSs is disrupted through the imbalance of histone acetyltransferases and histone deacetylase activity. Furthermore, dysregulation of microRNAs (miRNAs) is immense. Most of these miRNAs have shown an aberrant expression in FLSs that are involved in proliferation and cytokine production. Besides, dysregulation of long noncoding RNAs in FLSs has been revealed and attributed to RA pathogenesis. Further investigations are needed to get a better view of epigenetic alterations and their interactions. We also discuss the role of these epigenetic alterations in RA pathogenesis and their therapeutic potential.

An Overview of the Intrinsic Role of Citrullination in Autoimmune Disorders

A protein undergoes many types of posttranslation modification. Citrullination is one of these modifications, where an arginine amino acid is converted to a citrulline amino acid. This process depends on catalytic enzymes such as peptidylarginine deiminase enzymes (PADs). This modification leads to a charge shift, which affects the protein structure, protein-protein interactions, and hydrogen bond formation, and it may cause protein denaturation. The irreversible citrullination reaction is not limited to a specific protein, cell, or tissue. It can target a wide range of proteins in the cell membrane, cytoplasm, nucleus, and mitochondria. Citrullination is a normal reaction during cell death. Apoptosis is normally accompanied with a clearance process via scavenger cells. A defect in the clearance system either in terms of efficiency or capacity may occur due to massive cell death, which may result in the accumulation and leakage of PAD enzymes and the citrullinated peptide from the necrotized cell which could be recognized by the immune system, where the immunological tolerance will be avoided and the autoimmune disorders will be subsequently triggered. The induction of autoimmune responses, autoantibody production, and cytokines involved in the major autoimmune diseases will be discussed.

Investigating Asthma, Allergic Disease, Passive Smoke Exposure, and Risk of Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is postulated to originate at mucosal surfaces, particularly the airway mucosa. To investigate this hypothesis, we determined the association between RA and asthma, passive smoke exposure, and age at start of smoking.

METHODS

For this case-control study, we identified 1,023 cases of RA (175 incident) within a single-center biobank population, using a rules-based algorithm that combined self-report with 2 diagnostic codes. Exposures were self-reported on biobank questionnaires. Logistic regression models were used to calculate the association of exposures with RA, adjusting for potential confounders. Odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated.

RESULTS

After adjustment for allergies, urban environment, and passive smoke exposure, asthma was found to be associated with RA in the full cohort (OR 1.28 [95% CI 1.04-1.58; P = 0.02]) but not the incident RA cohort (OR 1.17 [95% CI 0.66-2.06; P = 0.60]). History of allergic disease was associated with RA in both the full cohort (OR 1.30 [95% CI 1.12-1.51; P < 0.001]) and the incident RA cohort (OR 1.61 [95% CI 1.11-2.33; P = 0.01]), especially food allergy, which was significantly associated with RA in the full cohort (OR 1.38 [95% CI 1.08-1.75; P = 0.01]) and showed a trend toward significance in the incident RA cohort (OR 1.83 [95% CI 0.97-3.45; P = 0.06]). Passive smoke exposure at home or work was not associated with RA. Finally, age at start of smoking was not associated with increased odds of developing RA in either the full cohort (OR 1.03 [95% CI 1.00-1.06; P = 0.03]) or the incident RA cohort (OR 1.00 [95% CI 0.92-1.08; P = 0.98]).

CONCLUSION

Asthma and allergies may be associated with increased risk of RA. Passive smoke exposure and early age at start of smoking do not appear to influence risk of RA.

Potential of Lifestyle Changes for Reducing the Risk of Developing Rheumatoid Arthritis: Is an Ounce of Prevention Worth a Pound of Cure?

PURPOSE

Lifestyle may be important in the development of rheumatoid arthritis (RA). Therefore, changing behaviors may delay or even prevent RA onset. This article reviews the evidence basis for the associations of lifestyle factors with RA risk and considers future directions for possible interventions to reduce RA risk.

METHODS

The literature was reviewed for cross-sectional studies, case-control studies, cohort studies, and clinical trials investigating potentially modifiable lifestyle factors and RA risk or surrogate outcomes on the path toward development such as RA-related autoimmunity or inflammatory arthritis. The evidence related to cigarette smoking, excess weight, dietary intake, physical activity, and dental health for RA risk were summarized.

FINDINGS

Cigarette smoking has the strongest evidence base as a modifiable lifestyle behavior for increased seropositive RA risk. Smoking may increase seropositive RA risk through gene-environment interactions, increasing inflammation and citrullination locally in pulmonary/oral mucosa or systemically, thereby inducing RA-related autoimmunity. Prolonged smoking cessation may reduce seropositive RA risk. Evidence suggests that excess weight can increase RA risk, although this effect may differ according to sex, serologic status, and age at RA onset. TDietary intake may also affect RA risk: overall healthier patterns, high fish/omega-3 polyunsaturated fatty acid consumption, and moderate alcohol intake may reduce RA risk, whereas caffeine and sugar-sweetened soda consumption might increase RA risk. The impact of physical activity is less clear, but high levels may reduce RA risk. Periodontal disease might induce citrullination and RA-related autoimmunity, but the effect of dental hygiene behaviors on RA risk is unclear. Although the effect size estimates for these lifestyle factors on RA risk are generally modest, there may be relatively large public health benefits for targeted interventions given the high prevalence of these unhealthy behaviors. With the exception of smoking cessation, the impact of behavior change of these lifestyle factors on subsequent RA risk has not been established. Nearly all of the evidence for lifestyle factors and RA risk were derived from observational studies.

IMPLICATIONS

There are many potentially modifiable lifestyle factors that may affect RA risk. Improving health behaviors could have large public health benefits for RA risk given the high prevalence of many of the RA risk-related lifestyle factors. However, future research is needed to establish the effects of lifestyle changes on RA risk or surrogate outcomes such as RA-related autoimmunity or inflammatory arthritis.

Sequencing of the MHC region defines HLA-DQA1 as the major genetic risk for seropositive rheumatoid arthritis in Han Chinese population

OBJECTIVE

The strong genetic contribution of the major histocompatibility complex (MHC) region to rheumatoid arthritis (RA) has been generally attributed to human leukocyte antigen (HLA)-DRB1. However, due to the high polymorphisms and linkage disequilibrium within MHC, it is difficult to define novel and/or independent genetic risks using conventional HLA genotyping or chip-based microarray technology. This study aimed to identify novel RA risk variants by performing deep sequencing for MHC.

METHODS

We first conducted target sequencing for the entire MHC region in 357 anticitrullinated protein antibodies (ACPA)-positive patients with RA and 1001 healthy controls, and then performed HLA typing in an independent case-control cohort consisting of 1415 samples for validation. All study subjects were Han Chinese. Genetic associations for RA susceptibility and severity were analysed. Comparative modelling was constructed to predict potential functions for the newly discovered RA association variants.

RESULTS

HLA-DQα1:160D conferred the strongest and independent susceptibility to ACPA-positive RA (p=6.16×10^-36, OR=2.29). DRβ1:37N had an independent protective effect (p=5.81×10^-16, OR=0.49). As predicted by comparative modelling, the negatively charged DQα1:160D stabilises the dimer of dimers, thus may lead to an increased T cell activation. The negatively charged DRβ1:37N encoding alleles preferentially bind with epitope P9 arginine, thus may result in a decreased RA susceptibility.

CONCLUSIONS

We provide the first evidence that HLA-DQα1:160D, instead of HLA-DRB1*0405, is the strongest and independent genetic risk for ACPA-positive RA in Han Chinese. Our study also illustrates the value of deep sequencing for fine-mapping disease risk variants in the MHC region.

Association of fish intake and smoking with risk of rheumatoid arthritis and age of onset: a prospective cohort study

Background

Prior studies suggest that fish may be protective for rheumatoid arthritis (RA) risk perhaps through the anti-inflammatory effect of omega-3 fatty acid, but this relationship has not been clearly established. Therefore, we investigated fish intake and RA risk by serologic status, age of onset, and smoking using a prospective cohort study with large sample size, repeated measures of dietary intake, and lengthy follow-up.

Methods

We studied fish intake and RA risk among 166,013 women in two prospective cohorts, the Nurses’ Health Study (NHS, 1984–2014) and NHSII (1991–2015). Fish intake was assessed using food frequency questionnaires at baseline and every 4 years. Incident RA during follow-up and serologic status were determined by medical record review. Pooled Cox regression models estimated hazard ratios (HR) and 95% confidence intervals (CI) for RA (overall and by serologic status and age at diagnosis) for fish intake frequency. We tested for a smoking-fish interaction for RA risk.

Results

During 3,863,909 person-years of follow-up, we identified 1080 incident RA cases. Increasing fish intake was not associated with all RA (≥4 servings/week: multivariable HR 0.93 [95%CI 0.67–1.28] vs. < 1 serving/month; p for trend = 0.42), seropositive RA (p for trend = 0.66), or seronegative RA (p for trend = 0.45), but had increased risk for RA diagnosed > 55 years old (p for trend = 0.037). Among women ≤55 years old, frequent fish intake (vs. infrequent) had HRs (95%CIs) of: 0.73 (0.52–1.02) for all RA, 0.85 (0.55–1.32) for seropositive RA, and 0.55 (0.32–0.94) for seronegative RA. Ever smokers with infrequent fish intake had highly elevated risk for RA onset ≤55 years (HR 2.59, 95%CI 1.65–4.06), while ever smokers with frequent fish intake had modestly elevated RA risk (HR 1.29, 95%CI 1.07–1.57; vs. never smokers/frequent fish intake; p for smoking-fish interaction = 0.039).

Conclusion

In this large prospective cohort study, we found no clear protective effect of fish or marine omega-3 fatty acid intake on RA risk, overall or by serologic status. We found that fish intake attenuated the strong association of smoking for RA diagnosed ≤55 years of age, but this requires further study.

Prevalence and Incidence of Upper Respiratory Tract Infection Events Are Elevated Prior to the Development of Rheumatoid Arthritis in First-Degree Relatives

Introduction: The aim of this study was to characterize infection events in a longitudinal cohort of first-degree relatives (FDR) of probands with rheumatoid arthritis (RA) and explore their associations with RA development. To this end, newly diagnosed RA patients (n = 283), unaffected related FDR and age-matched healthy women were ascertained from the Caucasian triple women prospective Tatarstan cohort. Methods: In this cohort initiated in 1997, 26/283 (9.2%) FDR developed RA (incidence: 9.1 cases/1,000/year). At baseline and during the follow-up, information regarding infectious events (prevalence) and their incidence and duration per year were collected from all individuals. Results: Results reveal in the unaffected FDR developing RA subgroup: (i) a higher prevalence and/or incidence at baseline of upper respiratory infections (URI), otitis, tonsillitis, herpes reactivation, and skin infections; (ii) Mycoplasma sp detection was increased during pregnancy; (iii) a peak of infections started in the 3 years preceding RA onset, and thereafter decreased following RA diagnosis and treatment initiation with disease-modifying anti-rheumatic drugs (DMARDs) when considering URI, and acute tonsillitis; (iv) herpes virus reactivation, at baseline, was associated with a higher report of morning stiffness and arthralgia while independent from rheumatoid factors and anti-citrullinated peptide (CCP)2 Ab positivity; and (v) infection events represent an independent environmental factor associated with RA development. Conclusion: In conclusion, an annual increase of respiratory tract infections was found at the pre-clinical stage of RA. This could be due to alterations in the immune system that result in susceptibility to infection, controlled by DMARDs, or that the infectious events predispose to RA.

The Utilization of Autoantibodies in Approaches to Precision Health

Precision health (PH) applied to autoimmune disease will need paradigm shifts in the use and application of autoantibodies and other biomarkers. For example, autoantibodies combined with other multi-analyte “omic” profiles will form the basis of disease prediction allowing for earlier intervention linked to disease prevention strategies, as well as earlier, effective and personalized interventions for established disease. As medical intervention moves to disease prediction and a model of “intent to PREVENT,” diagnostics will include an early symptom/risk-based, as opposed to a disease-based approach. Newer diagnostic platforms that utilize emerging megatrends such as deep learning and artificial intelligence and close the gaps in autoantibody diagnostics will benefit from paradigm shifts thereby facilitating the PH agenda.

The Effect of Tobacco Smoking on Musculoskeletal Health: A Systematic Review

This systematic review explored associations between smoking and health outcomes involving the musculoskeletal system. AMSTAR criteria were followed. A comprehensive search of PubMed, Web of Science, and Science Direct returned 243 articles meeting inclusion criteria. A majority of studies found smoking has negative effects on the musculoskeletal system. In research on bones, smoking was associated with lower BMD, increased fracture risk, periodontitis, alveolar bone loss, and dental implant failure. In research on joints, smoking was associated with increased joint disease activity, poor functional outcomes, and poor therapeutic response. There was also evidence of adverse effects on muscles, tendons, cartilage, and ligaments. There were few studies on the musculoskeletal health outcomes of secondhand smoke, smoking cessation, or other modes of smoking, such as waterpipes or electronic cigarettes. This review found evidence that suggests tobacco smoking has negative effects on the health outcomes of the musculoskeletal system. There is a need for further research to understand mechanisms of action for the effects of smoking on the musculoskeletal system and to increase awareness of healthcare providers and community members of the adverse effects of smoking on the musculoskeletal system.

Rheumatoid arthritis and risk of chronic obstructive pulmonary disease or asthma among women: A marginal structural model analysis in the Nurses' Health Study

OBJECTIVE

We investigated whether RA increases risk for chronic obstructive pulmonary disease (COPD) or asthma independent of factors occurring before RA onset or mediating these respiratory morbidities after diagnosis, such as cigarette smoking.

METHODS

Within the prospective Nurses' Health Study (n = 121,701 women; 1976-2014), we identified an incident RA cohort and matched each woman with RA to 10 comparators without RA by age and year at index date of RA diagnosis, excluding women with COPD or asthma at baseline. Data were obtained through biennial questionnaires and medical records. We used marginal structural models to determine the independent effect of RA on incident COPD or asthma adjusting for confounders and time-varying mediators through inverse probability weighting.

RESULTS

We identified 843 women with RA, matched to 8,399 comparators without RA. Mean age was 59.8 years and mean follow-up after index date was 18.6 years (SD = 9.0) for women with RA, and 18.8 years (SD = 9.5) for comparators. We identified 68 (8.1%) incident COPD and 40 (4.7%) asthma cases among women with RA, and 459 (5.5%) COPD and 268 (3.2%) asthma cases among comparators. RA was associated with increased risk of COPD (HR = 1.52, 95% CI: 1.17-1.97) and asthma (HR = 1.55, 95% CI: 1.11-2.16) compared to comparators adjusted for the matching factors of age and calendar year at index date. After further adjustment for confounders and time-varying mediators occurring after index date, including smoking, RA was significantly associated with COPD (HR = 1.68, 95% CI: 1.36-2.07), but not asthma (HR = 1.11, 95% CI: 0.59-2.09) compared to non-RA comparators. Women with seropositive RA (HR = 1.60, 95% CI: 1.17-2.19) and seronegative RA (HR = 1.62, 95% CI: 1.09-2.40) had similar increased risk for COPD compared to non-RA comparators.

CONCLUSION

In this prospective cohort study, RA was associated with increased risk for incident COPD, independent of lifestyle confounders and mediators after diagnosis, including smoking.

Vasoactive intestinal peptide gene polymorphisms, associated with its serum levels, predict treatment requirements in early rheumatoid arthritis

We previously reported that early arthritis (EA) patients with low vasoactive intestinal peptide (VIP) serum levels demonstrate a worse clinical disease course. In this study, we analysed whether variants in the VIP gene correlated with its serum levels and clinical EA parameters. The VIP gene was sequenced in patients with extremely high/low VIP levels, measured by enzyme immunoassay. Sixteen single nucleotide polymorphisms (SNPs) were differentially distributed between both groups, which were subsequently genotyped in two patients’ sets. We observed that patients with rs688136 CC genotype showed higher VIP levels in both discovery (n = 91; p = 0.033) and validation populations (n = 131; p = 0.007). This effect was attenuated by the presence of minor alleles rs35643203 and rs12201140, which showed a clear trend towards low VIP level association (p = 0.118 and p = 0.049, respectively). Functional studies with miR-205-5p, which has a target site in the 3′ UTR close to rs688136, revealed a miRNA-mediated regulatory mechanism explaining the higher VIP gene expression in homozygous patients. Moreover, patients with an rs688136 CC genotype and no minor alleles of the other polymorphisms required less treatment (p = 0.009). We concluded that the identification of polymorphisms associated with VIP serum levels would complement the clinical assessment of the disease severity in rheumatoid arthritis patients.

PATHOGENESIS OF RHEUMATOID ARTHRITIS: THE INTERSECTION OF GENETICS AND EPIGENETICS

Rheumatoid arthritis is a synovial inflammatory disease marked by joint infiltration by immune cells and damage to the extracellular matrix. Although genetics plays a critical role in heritability and its pathogenesis, the relative lack of disease concordance in identical twins suggests that noncoding influences can affect risk and severity. Environmental stress, which can be reflected in the genome as altered epigenetic marks, also contributes to gene regulation and contributes to disease mechanisms. Studies on DNA methylation suggest that synovial cells, most notably fibroblast-like synoviocytes, are imprinted in rheumatoid arthritis with epigenetic marks and subsequently assume an aggressive phenotype. Even more interesting, the synoviocyte marks are not only disease specific but can vary depending on the joint of origin. Understanding the epigenetic landscape using unbiased methods can potentially identify nonobvious pathways and genes that that are responsible for synovial inflammation as well as the diversity of responses to targeted agents. The information can also be leveraged to identify novel therapeutic approaches.

Smoking Behavior Changes in the Early Rheumatoid Arthritis Period and Risk of Mortality During Thirty-Six Years of Prospective Followup

OBJECTIVE

To investigate whether rheumatoid arthritis (RA) diagnosis influences smoking behavior changes and whether these changes were associated with mortality.

METHODS

We identified an incident RA cohort in the Nurses' Health Study (NHS; 1976-2012). Behavioral data were collected through biennial questionnaires. We created a comparison cohort, matching RA cases to women without RA by age and calendar year at the index date of RA diagnosis. To investigate smoking behavior changes in the early RA period, sustained cessation was defined as permanently quitting within 4 years of the RA/index date. We used Cox regression to obtain hazard ratios (HRs) for mortality, comparing sustained smoking cessation to continued smoking.

RESULTS

Among 121,700 women in the NHS, we identified 938 with incident RA matched to 8,951 non-RA comparators. Among current smokers, 40.0% with RA permanently quit smoking in the early RA period, compared to 36.1% of comparators (odds ratio for sustained cessation 1.18 [95% confidence interval (95% CI) 0.88, 1.58]). There were 313 deaths (33.4%) in the RA cohort and 2,042 (22.8%) among comparators. Compared to continued smoking, sustained cessation was associated with similarly decreased mortality in both the RA (HR 0.58 [95% CI 0.33, 1.01]) and comparison (HR 0.47 [95% CI 0.39, 0.58]) cohorts. Women with RA had higher mortality for >5 post-RA pack-years (HR 3.67 [95% CI 2.80, 4.81]) than comparators with >5 post-index pack-years (HR 1.88 [95% CI 1.62, 2.17]; P < 0.001 for interaction; reference: ever-smoker non-RA women with 0 post-index pack-years).

CONCLUSION

Sustained smoking cessation within 4 years of RA diagnosis reduced mortality risk, with a similar effect observed among non-RA comparators. Smoking >5 pack-years after RA diagnosis significantly increased mortality beyond the risk of non-RA comparators.

The association between omega-3 fatty acid biomarkers and inflammatory arthritis in an anti-citrullinated protein antibody positive population

Objectives

Higher circulating omega-3 fatty acids (n-3 FAs) are associated with a lower prevalence of anti-CCP antibodies and RF in subjects without RA. We examined whether, in anti-CCP+ subjects, n-3 FAs also play a role in development of inflammatory arthritis (IA).

Methods

At Colorado-based health fairs from 2008 to 2014, participants without a previous diagnosis of RA who were anti-CCP3+ (n = 47) were recruited into a follow-up study; symptom assessments and joint examinations were conducted every 6 months for the determination of IA. We measured n-3 FAs as a percentage of total lipids in red blood cell membranes (n-3 FA%) at each visit.

Results

We detected IA in 10 anti-CCP3+ subjects (21%) at the baseline visit. Increased total n-3 FA% in red blood cell membranes [odds ratio (OR) = 0.09, 95% CI: 0.01, 0.76], specifically docosapentaenoic acid (OR = 0.16, 95% CI: 0.03, 0.83) and docosahexaenoic acid (OR = 0.23, 95% CI: 0.06, 0.86), was associated with a lower odds of IA at the baseline visit, adjusting for n-3 FA supplement use, current smoking, RF+, elevated CRP+ and shared epitope. We followed 35 of the anti-CCP3+ subjects who were IA negative at baseline and detected 14 incident IA cases over an average of 2.56 years of follow-up. In a time-varying survival analysis, increasing docosapentaenoic acid significantly decreased risk of incident IA (hazard ratio = 0.52, 95% CI: 0.27, 0.98), adjusting for age at baseline, n-3 FA supplement use, RF+, CRP+ and shared epitope.

Conclusion

n-3 FAs may potentially lower the risk of transition from anti-CCP positivity to IA, an observation that warrants further investigation.

Epigenetic alterations in rheumatoid arthritis fibroblast-like synoviocytes

Rheumatoid arthritis is an immune-mediated disease that primarily affects diarthrodial joints. Susceptibility and severity of this disease are influenced by nongenetic factors, such as environmental stress, suggesting an important role of epigenetic changes. In this review, we summarize the epigenetic changes (DNA methylation, histone modification and miRNA expression) in fibroblast-like synoviocytes, which are the joint-lining mesenchymal cells that play an important role in joint inflammation and damage. We also review the effects of these epigenetic changes on rheumatoid arthritis pathogenesis and discuss their therapeutic potential.

Effect of Tobacco Smoking on The Clinical, Histopathological, and Serological Manifestations of Sjögren's Syndrome

Objectives

To assess the association of smoking habits with the clinical, serological, and histopathological manifestations of Sjögren’s syndrome (SS) and non-Sjögren’s sicca (non-SS sicca).

Methods

Cross-sectional case-control study of 1288 patients with sicca symptoms (587 SS and 701 non-SS sicca) evaluated in a multi-disciplinary research clinic. Smoking patterns were obtained from questionnaire data and disease-related clinical and laboratory data were compared between current, past, ever, and never smokers.

Results

Current smoking rates were 4.6% for SS patients compared to 14.1% in non-SS sicca (p = 5.17x10E-09), 18% in a local lupus cohort (p = 1.13x10E-14) and 16.8% in the community (p = 4.12x10E-15). Current smoking was protective against SS classification (OR 0.35, 95%CI 0.22–0.56, FDR q = 1.9E10-05), focal lymphocytic sialadenitis (OR 0.26, 95%CI 0.15–0.44, FDR q = 1.52x10E-06), focus score ≥1 (OR 0.22, 95%CI 0.13–0.39, FDR q = 1.43x10E-07), and anti-Ro/SSA(+) (OR 0.36, 95%CI 0.2–0.64, FDR q = 0.0009); ever smoking was protective against the same features and against anti-La/SSB(+) (OR 0.52, 95%CI 0.39–0.70, FDR q = 5.82x10E-05). Duration of smoking was inversely correlated with SS even after controlling for socioeconomic status, BMI, alcohol and caffeine consumption.

Conclusions

Current tobacco smoking is negatively and independently associated with SS, protecting against disease-associated humoral and cellular autoimmunity. The overall smoking rate amongst SS patients is significantly lower than in matched populations and the effects of smoking are proportional to exposure duration.

In spite of the protective effects of tobacco on SS manifestations, it is associated with other serious comorbidities such as lung disease, cardiovascular risk and malignancy, and should thus be strongly discouraged in patients with sicca.

Genetic and environmental risk factors for rheumatoid arthritis

Multiple genetic and environmental factors have been associated with an increased risk for rheumatoid arthritis (RA). Of these, the strongest associations have been seen with female sex, a family history of RA, the genetic factor the "shared epitope," and exposure to tobacco smoke. There is also renewed interest in mucosal inflammation and microbial factors as contributors to the development of RA. However, the identification of a "preclinical" period of RA that can be defined as local or systemic autoimmunity as measured by autoantibodies and other biomarkers prior to the development of clinically apparent synovitis suggests that the risk factors for RA are acting long prior to first clinical evidence of IA. As such, a major challenge to the field will be to investigate the full spectrum of the development of RA, from initiation and propagation of autoimmunity during preclinical RA and transition to clinically apparent synovitis and classifiable RA, to determine which genetic and environmental factors are important at each stage of disease development. Understanding the exact role and timing of action of risk factors for RA is especially important given the advent of prevention trials in RA, and the hope that a full understanding of genetic and environmental factors in RA could lead to effective preventive interventions.

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.

Gender differences in systemic sclerosis: relationship to clinical features, serologic status and outcomes

INTRODUCTION

There is a strong female preponderance reported in many connective tissue diseases and in almost all systemic sclerosis (SSc) case series.

METHODS

We compared gender differences in SSc patients in a large single-center cohort, including demographic features, disease subtype, environmental exposures, disease-specific serum autoantibodies, organ system involvement (frequency and severity) and survival. Adjustment for cutaneous subset (diffuse cutaneous [dc] and limited cutaneous [lc]) was performed.

RESULTS

We identified key characteristics which distinguished female from male SSc patients. Females were more frequently younger at disease onset with a longer disease duration at the time of their first visit. Females more often had lcSSc and, if an overlap syndrome was present, it was most often systemic lupus erythematosus. In contrast, males more frequently had dcSSc and overlap with myositis. Females more frequently had peripheral vascular involvement but in males it was more often severe. Males were more often cigarette smokers and more frequently had environmental exposures. Males more frequently had interstitial lung disease (ILD or pulmonary fibrosis) which was more severe. Females had a significantly increased frequency of anti-centromere antibody and males anti-topoisomerase I and anti-U3RNP antibody. Males had significantly reduced survival (73% at 5 years and 45% at 10 years after onset of SSc). The most frequent causes of death were ILD in males and pulmonary hypertension in females.

CONCLUSIONS

Gender differences may be important clues to understanding the natural history and pathogenesis of SSc.

The Roles of Cigarette Smoking and the Lung in the Transitions Between Phases of Preclinical Rheumatoid Arthritis

While the etiology of rheumatoid arthritis (RA) remains to be fully elucidated, recent research has advanced the understanding of RA pathogenesis to the point where clinical trials for RA prevention are underway. The current paradigm for RA pathogenesis is that individuals progress through distinct preclinical phases prior to the onset of clinically apparent RA. These preclinical RA phases consist of genetic risk, local inflammation, presence of RA-related autoantibodies, asymptomatic systemic inflammation, and early non-specific symptoms prior to clinical seropositive RA. Epidemiologic studies have been important in forming hypotheses related to the biology occurring in preclinical RA. Specifically, studies associating cigarette smoking with overall RA risk as well as transitions between phases of preclinical RA were vital in helping to establish the lung as a potential important initiating site in the pathogenesis of seropositive RA. Herein, we review the epidemiology associating smoking with transitions in preclinical phases of RA as well as the recent literature supporting the lung as a critical site in RA pathogenesis.