Silica exposure is associated with increased risk of developing rheumatoid arthritis: results from the Swedish EIRA study

[Influence of smoking, nutrition and other modifiable environmental factors on rheumatoid arthritis]

Numerous reports in recent years have focused on the influence of environmental factors on rheumatoid arthritis. This article provides an overview of the current study situation on the influence of modifiable environmental factors on the development and course of rheumatoid arthritis. Lifestyle factors, such as cigarette smoking, diet, exercise and body weight can be individually influenced. Factors such as air pollution and socioeconomic status can be influenced by environmental and sociopolitical measures at a public level. Epidemiological studies have identified nicotine abuse, an unhealthy diet and obesity as well as a low level of education and social status as risk factors for the development of rheumatoid arthritis. Numerous factors are also associated with a poorer response to treatment and a worse prognosis. As randomized interventional studies on most environmental factors are hardly feasible, the causal relationship of the individual factors to the incidence and progression of rheumatoid arthritis is difficult to quantify. Nevertheless, the current evidence already enables the provision of appropriate counselling to patients with rheumatoid arthritis with respect to a healthy lifestyle including abstaining from cigarette smoking, maintaining a healthy diet, physical activity and avoiding obesity.

The Lung in Rheumatoid Arthritis-Friend or Enemy?

Rheumatoid arthritis (RA) is a chronic autoimmune condition frequently found in rheumatological patients that sometimes raises diagnosis and management problems. The pathogenesis of the disease is complex and involves the activation of many cells and intracellular signaling pathways, ultimately leading to the activation of the innate and acquired immune system and producing extensive tissue damage. Along with joint involvement, RA can have numerous extra-articular manifestations (EAMs), among which lung damage, especially interstitial lung disease (ILD), negatively influences the evolution and survival of these patients. Although there are more and more RA-ILD cases, the pathogenesis is incompletely understood. In terms of genetic predisposition, external environmental factors act and subsequently determine the activation of immune system cells such as macrophages, neutrophils, B and T lymphocytes, fibroblasts, and dendritic cells. These, in turn, show the ability to secrete molecules with a proinflammatory role (cytokines, chemokines, growth factors) that will produce important visceral injuries, including pulmonary changes. Currently, there is new evidence that supports the initiation of the systemic immune response at the level of pulmonary mucosa where the citrullination process occurs, whereby the autoantibodies subsequently migrate from the lung to the synovial membrane. The aim of this paper is to provide current data regarding the pathogenesis of RA-associated ILD, starting from environmental triggers and reaching the cellular, humoral, and molecular changes involved in the onset of the disease.

Immune response to post-translationally modified proteins in rheumatoid arthritis: what makes it special?

Rheumatoid arthritis (RA) exhibits common characteristics with numerous other autoimmune diseases, including the presence of susceptibility genes and the presence of disease-specific autoantibodies. Anti-citrullinated protein antibodies (ACPA) are the hallmarking autoantibodies in RA and the anti-citrullinated protein immune response has been implicated in disease pathogenesis. Insight into the immunological pathways leading to anti-citrullinated protein immunity will not only aid understanding of RA pathogenesis, but may also contribute to elucidation of similar mechanisms in other autoantibody-positive autoimmune diseases. Similarly, lessons learnt in other human autoimmune diseases might be relevant to understand potential drivers of RA. In this review, we will summarise several novel insights into the biology of the anti-citrullinated protein response and their clinical associations that have been obtained in recent years. These insights include the identification of glycans in the variable domain of ACPA, the realisation that ACPA are polyreactive towards other post-translational modifications on proteins, as well as new awareness of the contributing role of mucosal sites to the development of the ACPA response. These findings will be mirrored to emerging concepts obtained in other human (autoimmune) disease characterised by disease-specific autoantibodies. Together with an updated understanding of genetic and environmental risk factors and fresh perspectives on how the microbiome could contribute to antibody formation, these advancements coalesce to a progressively clearer picture of the B cell reaction to modified antigens in the progression of RA.

Food-derived bioactive peptides potentiating therapeutic intervention in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that affects the joints of the human body and is projected to have a prevalence age-standardized rate of 1.5 million new cases worldwide by 2030. Several conventional and non-conventional preventive and therapeutic interventions have been suggested but they have their side effects including nausea, abdominal pain, liver damage, ulcers, heightened blood pressure, coagulation, and bleeding. Interestingly, several food-derived peptides (FDPs) from both plant and animal sources are increasingly gaining a reputation for their potential in the management or therapy of RA with little or no side effects. In this review, the concept of inflammation, its major types (acute and chronic), and RA identified as a chronic type were discussed based on its pathogenesis and pathophysiology. The conventional treatment options for RA were briefly outlined as the backdrop of introducing the FDPs that potentiate therapeutic effects in the management of RA.

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

INTRODUCTION

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

OBJECTIVE

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

DESIGN

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

RESULTS

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

CONCLUSION

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

No causal association between pneumoconiosis and three inflammatory immune diseases: a Mendelian randomization study

Objectives

To investigate the causal relationships between pneumoconiosis and rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and gout.

Methods

The random-effects inverse variance weighted (IVW) approach was utilized to explore the causal effects of the instrumental variables (IVs). Sensitivity analyses using the MR-Egger and weighted median (WM) methods were did to investigate horizontal pleiotropy. A leave-one-out analysis was used to avoid the bias resulting from single-nucleotide polymorphisms (SNPs).

Results

There was no causal association between pneumoconiosis and SLE, RA or gout in the European population [OR = 1.01, 95% CI: 0.94-1.10, p = 0.74; OR = 1.00, 95% CI: 0.999-1.000, p = 0.50; OR = 1.00, 95% CI: 1.000-1.001, p = 0.55]. Causal relationships were also not found in pneumoconiosis due to asbestos and other mineral fibers and SLE, RA and gout [OR = 1.01, 95% CI: 0.96-1.07, p = 0.66; OR = 1.00, 95% CI: 1.00-1.00, p = 0.68; OR = 1.00, 95% CI: 1.00-1.00, p = 0.20].

Conclusion

Our study suggests that pneumoconiosis may have no causal relationship with the three inflammatory immune diseases.

Rheumatoid arthritis and the intestinal microbiome: probiotics as a potential therapy

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by swollen joints, discomfort, stiffness, osteoporosis, and reduced functionality. Genetics, smoking, dust inhalation, high BMI, and hormonal and gut microbiota dysbiosis are all likely causes of the onset or development of RA, but the underlying mechanism remains unknown. Compared to healthy controls, patients with RA have a significantly different composition of gut microbiota. It is well known that the human gut microbiota plays a key role in the initiation, maintenance, and operation of the host immune system. Gut microbiota dysbiosis has local or systematic adverse effects on the host immune system, resulting in host susceptibility to various diseases, including RA. Studies on the intestinal microbiota modulation and immunomodulatory properties of probiotics have been reported, in order to identify their potential possibility in prevention and disease activity control of RA. This review summarized current studies on the role and potential mechanisms of gut microbiota in the development and progression of RA, as well as the preventative and therapeutic effects and potential mechanisms of probiotics on RA. Additionally, we proposed the challenges and difficulties in the application of probiotics in RA, providing the direction for the research and application of probiotics in the prevention of RA.

Association between sinusitis and incident rheumatic diseases: a population-based study

OBJECTIVES

To determine whether antecedent sinusitis is associated with incident rheumatic disease.

METHODS

This population-based case-control study included all individuals meeting classification criteria for rheumatic diseases between 1995 and 2014. We matched three controls to each case on age, sex and length of prior electronic health record history. The primary exposure was presence of sinusitis, ascertained by diagnosis codes (positive predictive value 96%). We fit logistic regression models to estimate ORs for incident rheumatic diseases and disease groups, adjusted for confounders.

RESULTS

We identified 1729 incident rheumatic disease cases and 5187 matched controls (mean age 63, 67% women, median 14 years electronic health record history). After adjustment, preceding sinusitis was associated with increased risk of several rheumatic diseases, including antiphospholipid syndrome (OR 7.0, 95% CI 1.8 to 27), Sjögren's disease (OR 2.4, 95% CI 1.1 to 5.3), vasculitis (OR 1.4, 95% CI 1.1 to 1.9) and polymyalgia rheumatica (OR 1.4, 95% CI 1.0 to 2.0). Acute sinusitis was also associated with increased risk of seronegative rheumatoid arthritis (OR 1.8, 95% CI 1.1 to 3.1). Sinusitis was most associated with any rheumatic disease in the 5-10 years before disease onset (OR 1.7, 95% CI 1.3 to 2.3). Individuals with seven or more codes for sinusitis had the highest risk for rheumatic disease (OR 1.7, 95% CI 1.3 to 2.4). In addition, the association between sinusitis and incident rheumatic diseases showed the highest point estimates for never smokers (OR 1.7, 95% CI 1.3 to 2.2).

CONCLUSIONS

Preceding sinusitis is associated with increased incidence of rheumatic diseases, suggesting a possible role for sinus inflammation in their pathogenesis.

Detection of Mycobacterium avium Subspecies paratuberculosis in the Blood of Patients with Rheumatoid Arthritis by Using Serological and Molecular Techniques

The role of Mycobacterium avium subspecies paratuberculosis (MAP) in triggering rheumatoid arthritis (RA) could be a population-specific phenomenon. This study explored the relationship between MAP and RA using serological and molecular techniques; In this case-control study, 239 Iranian participants, including 120 RA patients and 119 controls, were enrolled. The indirect ELISA was designed to diagnose antibodies against MAP3865c125-133 and Zinc transporter 8 (ZnT8)178-186. The Nested-Polymerase Chain Reaction (PCR) detected MAP in blood; The frequency of MAP in RA patients and controls was 31.9% and 12.5%, respectively (P = 0.002). The antibodies against MAP3865c125-133 and ZnT8178-186 were 42.9% and 37% in RA patients and 14.2% and 11.7% in the controls, respectively (P < 0.0001). Interestingly, positive ELISA results in previously diagnosed (PD) RA were more common than newly diagnosed (ND) RA patients (P < 0.05).; The findings showed a higher frequency of MAP and its antibodies in the RA patients than in the controls. This data indicated MAP as one of RA's predisposing factors. Also, this first report implies the high positivity of MAP in Iranian RA patients.

Advancement in nanotechnology for treatment of rheumatoid arthritis: scope and potential applications

Rheumatoid arthritis is a hyperactive immune disorder that results in severe inflammation in synovial joints, cartilage, and bone deterioration, resulting in immobilization of joints. Traditional approaches for the treatment of rheumatoid arthritis are associated with some limiting factors such as suboptimal patient compliance, inability to control the progression of disorder, and safety concerns. Therefore, innovative drug delivery carriers for efficient therapeutic delivery at inflamed synovial sites with better safety assessment are urgently needed to address these issues. From this perspective, nanotechnology is an outstanding alternative to traditional drug delivery approaches, and it has shown great promise in developing novel carriers to treat rheumatoid arthritis. Considering the current research and future application of nanocarriers, it is believed that nanocarriers can be a crucial element in rheumatoid arthritis treatment. This paper covers all currently available pathophysiological aspects of rheumatoid arthritis and treatment options. Future research for the reduction of synovial inflammation should focus on developing multifunction nanoparticles capable of delivering therapeutic agents with improved safety, efficacy, and cost-effectiveness to be commercialized.

Etiology and Pathogenesis of Rheumatoid Arthritis-Interstitial Lung Disease

Interstitial lung disease (ILD) is one of the most serious extra-articular complications of rheumatoid arthritis (RA), which increases the mortality of RA. Because the pathogenesis of RA-ILD remains poorly understood, appropriate therapeutic strategies and biomarkers have not yet been identified. Thus, the goal of this review was to summarize and analyze the reported data on the etiology and pathogenesis of RA-ILD. The incidence of RA-ILD increases with age, and is also generally higher in men than in women and in patients with specific genetic variations and ethnicity. Lifestyle factors associated with an increased risk of RA-ILD include smoking and exposure to pollutants. The presence of an anti-cyclic citrullinated peptide antibody, high RA disease activity, and rheumatoid factor positivity also increase the risk of RA-ILD. We also explored the roles of biological processes (e.g., fibroblast-myofibroblast transition, epithelial-mesenchymal transition, and immunological processes), signaling pathways (e.g., JAK/STAT and PI3K/Akt), and the histopathology of RA involved in RA-ILD pathogenesis based on published preclinical and clinical models of RA-ILD in animal and human studies.

Association between exposure to external airborne agents and autoimmune disease

The etiology of autoimmune disease pathogeneses remains obscure, and the impact of general environmental or occupational exposure to external airborne agents (EAA) on autoimmune diseases remains understudied. This study was conducted to elucidate the association between exposure to EAA and the risk of autoimmune diseases according to exposure type. From the NHIS-NSC (2002-2019), 17,984,963 person-years were included in the data analysis. Autoimmune diseases were categorized based on the InterLymph classification. We estimated the incidence and rate ratio of autoimmune diseases according to the EAA exposure. Association between exposure and autoimmune diseases was investigated using logistic regression analysis, adjusted for potential confounders. Of the 1,082,879 participants, 86,376 (8.0%) were diagnosed with autoimmune diseases. Among these, 208 (14.1%) experienced severe exposure to EAA. Total EAA exposure was significantly associated with any autoimmune disease (OR: 1.29, 95% CI: 1.11-1.49) and organ-specific diseases (OR: 1.28, 95% CI: 1.08-1.53). Inorganic dust exposure was associated with organ-specific diseases (OR, 1.38; 95% CI: 1.01-1.81). Exposure to other dust was significantly associated with any autoimmune disease (OR: 1.35, 95% CI: 1.10-1.66), connective tissue diseases (OR: 1.43, 95% CI: 1.03-1.99), and organ-specific diseases (OR: 1.28, 95% CI: 1.00-1.65). Exposure to EAA was predominantly related to psoriasis, rheumatoid arthritis (RA), and type 1 diabetes (T1DM). We found that exposure to EAA is a potential risk factor for autoimmune diseases, especially psoriasis, RA, and T1DM. Our findings provide insight into the role of exposure to severe airborne agents in the pathogenesis of autoimmune diseases.

Are cleaning activities a source of exposure to crystalline silica in women with rheumatoid arthritis? A case-control study

INTRODUCTION

Inhalation of crystalline silica (silicon dioxide, SiO2) is associated with a wide range of acute and chronic diseases, including rheumatoid arthritis (RA). The objectives of this work were to identify the main sources of exposure to SiO2 in a series of patients with RA not selected on the basis of their professional activity, compared with a representative sample of the French general population, and to assess the association between silica exposure and disease features.

METHODS

The Dust Exposure Life-Course Questionnaire (DELCQ) is a tool that enables retrospective quantification of both occupational and non-occupational lifetime exposure to SiO2. DELCQ-previously validated in a large representative sample of the French general population-was administered to 97 consecutive RA patients, and exposure scores were compared between cases and age, gender and smoking status-matched controls (1:4). The main sources of SiO2 exposure were identified in cases and controls, and source-specific exposure levels were compared. The association between DELCQ scores and disease variables in cases was tested via univariable and multivariable analyses.

RESULTS

In women with RA, the main sources of SiO2 exposure were cleaning activities and dusty clothes laundry, with higher exposure levels from these sources versus the general population (p<0.005). Across the whole series of RA patients, high SiO2 exposure was independently associated with mediastinal lymphadenopathy (OR 6.3, 95% CI 1.4 to 27.7).

CONCLUSION

Cleaning activities and dusty clothes laundry may be underestimated sources of SiO2 exposure in women with RA.

Lifestyle Factors and Their Influence on Rheumatoid Arthritis: A Narrative Review

In recent years, a possible association of lifestyle factors with rheumatoid arthritis (RA) has attracted increasing public interest. The aim of this review is to provide an overview of the extent and the limitations of current evidence regarding lifestyle factors and RA. The PubMed medical database was screened for epidemiological and prospective studies investigating the contribution of lifestyle factors to the development and the course of the disease. Large epidemiological studies have identified smoking, unhealthy diet and adiposity, as well as a low educational level and low socioeconomic status, as factors that increase the incidence of RA. In addition, several lifestyle habits influence the response of RA to antirheumatic drugs. Among others, smoking, obesity and poor physical activity are associated with a worse treatment outcome. Methodological problems often impair firm conclusions with respect to the causal role of these factors in the risk and the course of RA. However, current evidence is sufficient to recommend a healthy diet, the prevention of obesity, the cessation of smoking and the maintenance of a high level of physical activity to support the effectivity of modern antirheumatic medication.

Epidemiologic Opportunities and Challenges in Studying Environmental Risk Factors for Rheumatic Diseases

Most rheumatic diseases have a stronger environmental than hereditary etiology. This article summarizes the key environmental risk factors for rheumatic diseases, the data sources that generated these findings, and the key pitfalls with existing research that every rheumatology clinician should know. Emerging research opportunities hold promise to revolutionize this field, and soon.

Ocular manifestations of rheumatoid arthritis

PURPOSE OF REVIEW

This article summarizes the pathophysiology of rheumatoid arthritis and common ocular manifestations that it is associated with: keratoconjunctivitis sicca, episcleritis, scleritis, and peripheral ulcerative keratitis.

RECENT FINDINGS

Newer biologic agents are being used to effectively treat rheumatoid arthritis and its ocular manifestations.

SUMMARY

The eye is a frequent extra-articular site of inflammation in patients with rheumatoid arthritis. Ocular involvement can range from more benign conditions such as keratoconjunctivitis sicca and episcleritis, to potentially vision and globe-threatening diseases like scleritis and peripheral ulcerative keratitis. Clinicians should be aware of these ophthalmic manifestations and the various treatment options that are available. Coordination between ophthalmology and rheumatology is helpful in the treatment of these patients.

A Retrospective Study of the Clinical, Radiological, and Pathological Characteristics of Patients with Interstitial Pneumonia Preceding Rheumatoid Arthritis

Objective Interstitial lung disease (ILD) is the most critical manifestation in patients with rheumatoid arthritis (RA). In some cases, ILD may appear before the RA onset. Some patients with an initial diagnosis of idiopathic interstitial pneumonia (IIPs) develop RA; however, few studies have reported on its features, and the details remain unknown. In the present study, the clinical, radiological, and pathological features were evaluated in patients with ILD preceding RA. Methods The clinical, radiological, and pathological features of patients with ILD preceding RA were retrospectively reviewed using the medical records. Patients Ten patients with ILD preceding RA out of 883 IIP patients who underwent a surgical lung biopsy at our hospital from 2004 to 2018 were retrospectively examined. Results The median patient age was 59 (range 50-76) years old, and 7 of the patients were women. The median time from the ILD diagnosis to the RA onset was 50 (range 33-65) months. Regarding the high-resolution computed tomography pattern, the "indeterminate for UIP" pattern was the most popular, and cysts were seen in all cases. Attenuation around the cyst was prominent. Pathological findings showed plasma cell infiltration, bronchus-associated lymphoid tissue (BALT), and bronchiolitis in the lobules. Cellular and destructive bronchiolitis was noticeable in many patients with ILD preceding RA and contributed to the destruction and dilation of the bronchiole. Conclusion In ILD patients with IIP, radiological and pathological findings with increased attenuation around the cysts, prominent inflammatory cell infiltration (especially in plasma cells), an increase in the BALT number, and cellular and destructive bronchiolitis might serve as helpful RA development indicators.

Evidence-based core information for health communication of tobacco control: The effect of smoking on risks of female disease

Objective

Cigarettes have become the the biggest killer of contemporary female's health and beauty. What kind of health information is suitable for the general public is an important issue to be discussed globally. The purpose of this study is to generate systematic, rigorous, public-demand-oriented and appropriate core information relevant to tobacco control based on the best available evidence, combined with audience preferences and pre-dissemination content review from multidisciplinary expertise in order to improve the effectiveness of health communication of tobacco control.

Methods

Relevant systematic reviews meta-analysis that reported smoking on risks of female disease were identified by searching PubMed, Embase, the Cochrane Library, Web of Science, Clinical Trials.gov, and the International Clinical Trial Registry Platform. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) process was applied to assess the evidence in order to make rigorous core information. The audience prevalence survey was conducted to ensure that core information was targeted and tailored. Finally, the expert assessment was used for a pre-dissemination content review and to evaluate whether the core information was appropriate or not.

Results

The final core information consisted of eight parts concerning the effects of smoking and female cardiovascular disease, diabetes, rheumatoid arthritis, respiratory disease, digestive system disease, mental disease, non-pregnant female reproductive system disease, as well as pregnant women and their fetuses. A total of 35 items of core information suitable for dissemination was included and the quality of evidence, the degree of public demand and the outcome of pre-dissemination content review were reported.

Conclusion

The core information related to female cardiovascular system diseases, as well as liver cancer and upper gastrointestinal cancer is the preferred content for health communication of tobacco control. The quality of evidence for core information related to pregnant women and their infants, as well as diseases of reproductive system, respiratory system, and diabetes needs to be improved to meet high public demand. The core information related to mental disease is more suitable for dissemination to patients with mental illness than to the general public. Besides, dissemination of core information should be individualized. Evidence-based Core Information for Health Communication of Tobacco Control would be helpful to provide evidence support for health communication related to tobacco control and enhance public health literacy for international communities that have high smoking prevalence and related disease burden.

Beef intake and risk of rheumatoid arthritis: Insights from a cross-sectional study and two-sample Mendelian randomization

Background

Beef is common in daily diet, but its association with the risk of rheumatoid arthritis (RA) remains uncertain. The objective of this study is to explore the relationship between beef intake and the risk of RA.

Materials and methods

We investigated the association between beef intake and risk of RA by multivariate logistic regression, based on the National Health and Nutrition Examination Survey (NHANES) 1999–2016 involving 9,618 participants. The dose–response relationship between beef intake and RA was explored as well. Furthermore, we performed Mendelian randomization (MR) analysis to examine the causal effect of beef intake on RA. Genetic instruments for beef intake were selected from a genome-wide association study (GWAS) including 335,576 individuals from the UK Biobank study, and summary statistics relating to RA were obtained from a GWAS meta-analysis of 14,361 RA patients and 43,923 controls. The inverse-variance weighted (IVW) approach was used to estimate the causal association, and MR-Egger regression and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) test were applied to evaluate the pleiotropy and outliers.

Results

Compared with the lowest quintile (0 to ≤33.50 g/d), beef intake was found to be significantly associated with the risk of RA [odds ratio (OR): 1.94; 95% confidence interval (CI): 1.20–3.12] in the third quintile (50.26 to ≤76.50 g/d). Moreover, a reversed “U” dose–response relationship between beef and RA (Pnon–linearity = 0.023) was found. In the MR analysis, beef intake was associated with an increased risk of RA (OR: 3.05; 95% CI: 1.11–8.35; P = 0.030) by the IVW method. The results from MR-Egger regression and MR-PRESSO test showed that there were no pleiotropic variations and outliers.

Conclusion

This study indicated that there is suggestive evidence to support the causal effect of beef intake on the risk of RA, while further studies are warranted to elucidate the exact association.

Disease mechanisms in preclinical rheumatoid arthritis: A narrative review

In the last decades, the concept of preclinical rheumatoid arthritis (RA) has become established. In fact, the discovery that disease mechanisms start years before the onset of clinical RA has been one of the major recent insights in the understanding of RA pathogenesis. In accordance with the complex nature of the disease, preclinical events extend over several sequential phases. In a genetically predisposed host, environmental factors will further increase susceptibility for incident RA. In the initial steps of preclinical disease, immune disturbance mechanisms take place outside the joint compartment, namely in mucosal surfaces, such as the lung, gums or gut. Herein, the persistent immunologic response to altered antigens will lead to breach of tolerance and trigger autoimmunity. In a second phase, the immune response matures and is amplified at a systemic level, with epitope spreading and widening of the autoantibody repertoire. Finally, the synovial and bone compartment are targeted by specific autoantibodies against modified antigens, initiating a local inflammatory response that will eventually culminate in clinically evident synovitis. In this review, we discuss the elaborate disease mechanisms in place during preclinical RA, providing a broad perspective in the light of current evidence.

A toxicological profile of silica nanoparticles

Humans are regularly exposed to silica nanoparticles in environmental and occupational contexts, and these exposures have been implicated in the onset of adverse health effects. Existing reviews on silica nanoparticle toxicity are few and not comprehensive. There are natural and synthetic sources by which crystalline and amorphous silica nanoparticles are produced. These processes influence physiochemical properties, which are factors that can dictate toxicological effects. Toxicological assessment includes exposure scenario (e.g. environmental, occupational), route of exposure, toxicokinetics, and toxicodynamics. Broader considerations include pathology, risk assessment, regulation, and treatment after injury. This review aims to consolidate the most relevant and up-to-date research in these areas to provide an exhaustive toxicological profile of silica nanoparticles.

The Effect of Inhaled Air Particulate Matter SRM 1648a on the Development of Mild Collagen-Induced Arthritis in DBA/J Mice

Air pollution is considered to be one of a risk factor for rheumatoid arthritis (RA). Collagen-induced arthritis (CIA) is commonly used as a mouse model of human RA. However, the impact of specific particulate matter (PM) components on the incidence and severity of RA has still not been established. The aim of this study was to develop an experimental model of CIA suitable to test arthritogenicity of inhaled PM. A mild form of CIA was induced in DBA1/J mice inhaled with various components of SRM 1648a PM. The incidence and severity of arthritis was assessed, and the selected serum markers of autoimmunity and inflammation were determined. Clinical arthritis was observed from the booster CII immunisation onward. Anti-cyclic citrullinated peptide antibodies, a diagnostic marker of RA, were detected in serum of these mice. All inhaled pollutants, crude PM, PM with reduced organic content, ferric, and silica nanoparticles markedly increased CIA incidence and severity. The fastest progression of CIA development was caused by crude PM and was linked to enhanced serum levels of anti-CII IgG, the prominent arthritogenic autoantibodies. On the other hand, inhaled nanoparticles enhanced serum levels of TNFα, a major proinflammatory arthritogenic cytokine. We recommend this experimental model of mild CIA to test the mechanisms of arthritis exacerbation by inhaled air pollutants. Further studies are necessary to determine whether PM-aggravated arthritis is caused by inflammatory mediators translocated from inflamed lung into systemic circulation or whether PM translocated into the bloodstream directly exacerbate joint inflammation.

Interplay of Environmental, Individual and Genetic Factors in Rheumatoid Arthritis Provocation

In this review, we explore systemization of knowledge about the triggering effects of non-genetic factors in pathogenic mechanisms that contribute to the development of rheumatoid arthritis (RA). Possible mechanisms involving environmental and individual factors in RA pathogenesis were analyzed, namely, infections, mental stress, sleep deprivation ecology, age, perinatal and gender factors, eating habits, obesity and smoking. The non-genetic factors modulate basic processes in the body with the impact of these factors being non-specific, but these common challenges may be decisive for advancement of the disease in the predisposed body at risk for RA. The provocation of this particular disease is associated with the presence of congenital loci minoris resistentia. The more frequent non-genetic factors form tangles of interdependent relationships and, thereby, several interdependent external factors hit one vulnerable basic process at once, either provoking or reinforcing each other. Understanding the specific mechanisms by which environmental and individual factors impact an individual under RA risk in the preclinical stages can contribute to early disease diagnosis and, if the factor is modifiable, might be useful for the prevention or delay of its development.

Preclinical Autoimmune Disease: a Comparison of Rheumatoid Arthritis, Systemic Lupus Erythematosus, Multiple Sclerosis and Type 1 Diabetes

The preclinical phase of autoimmune disorders is characterized by an initial asymptomatic phase of varying length followed by nonspecific signs and symptoms. A variety of autoimmune and inflammatory manifestations can be present and tend to increase in the last months to years before a clinical diagnosis can be made. The phenotype of an autoimmune disease depends on the involved organs, the underlying genetic susceptibility and pathophysiological processes. There are different as well as shared genetic or environmental risk factors and pathophysiological mechanisms between separate diseases. To shed more light on this, in this narrative review we compare the preclinical disease course of four important autoimmune diseases with distinct phenotypes: rheumatoid arthritis (RA), Systemic Lupus Erythematosus (SLE), multiple sclerosis (MS) and type 1 diabetes (T1D). In general, we observed some notable similarities such as a North-South gradient of decreasing prevalence, a female preponderance (except for T1D), major genetic risk factors at the HLA level, partly overlapping cytokine profiles and lifestyle risk factors such as obesity, smoking and stress. The latter risk factors are known to produce a state of chronic systemic low grade inflammation. A central characteristic of all four diseases is an on average lengthy prodromal phase with no or minor symptoms which can last many years, suggesting a gradually evolving interaction between the genetic profile and the environment. Part of the abnormalities may be present in unaffected family members, and autoimmune diseases can also cluster in families. In conclusion, a promising strategy for prevention of autoimmune diseases might be to address adverse life style factors by public health measures at the population level.

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.

The Relationship between 9/11 Exposure, Systemic Autoimmune Disease, and Post-Traumatic Stress Disorder: A Mediational Analysis

The relationship between 9/11 exposure, systemic autoimmune disease (SAD) and mental health remains poorly understood. This report builds on a prior analysis of World Trade Center Health Registry data to determine whether 9/11 exposure is associated with higher risk of SAD, and if so, whether post-traumatic stress disorder (PTSD) is a mediating factor and whether the association varies by responder/community member status. The final analytic sample comprised 41,656 enrollees with 123 cases of SAD diagnosed post 9/11 through November 2017. SAD diagnosis was ascertained from survey responses and confirmed by medical record review or physician survey. Logistic regression models were constructed to determine the relationship between 9/11 exposure and PTSD and SAD. Causal mediation analysis was used to determine the mediational effect of PTSD. Each analysis was stratified by 9/11 responder/community member status. Rheumatoid arthritis (n = 75) was the most frequent SAD, followed by Sjögren’s syndrome (n = 23), systemic lupus erythematosus (n = 20), myositis (n = 9), mixed connective tissue disease (n = 7), and scleroderma (n = 4). In the pooled cohort, those with 9/11-related PTSD had 1.85 times the odds (95% CI: 1.21–2.78) of SAD. Among responders, those with dust cloud exposure had almost twice the odds of SAD, while among community members, those with 9/11-related PTSD had 2.5 times the odds of SAD (95% CI: 1.39, 4.39). PTSD was not a significant mediator. Although emerging evidence suggests 9/11 exposure may be associated with SAD, more research is needed, particularly using pooled data sources from other 9/11-exposed cohorts, to fully characterize this relationship.

Antibodies to cartilage oligomeric matrix protein are pathogenic in mice and may be clinically relevant in rheumatoid arthritis

Objective

Cartilage oligomeric matrix protein (COMP) is an autoantigen in rheumatoid arthritis (RA) and experimental models of arthritis. This study was undertaken to investigate the structure, function, and relevance of anti‐COMP antibodies.

Methods

We investigated the pathogenicity of monoclonal anti‐COMP antibodies in mice using passive transfer experiments, and we explored the interaction of anti‐COMP antibodies with cartilage using immunohistochemical staining. The interaction of the monoclonal antibody 15A11 in complex with its specific COMP epitope P6 was determined by x‐ray crystallography. An enzyme‐linked immunosorbent assay and a surface plasma resonance technique were used to study the modulation of calcium ion binding to 15A11. The clinical relevance and value of serum IgG specific to the COMP P6 epitope and its citrullinated variants were evaluated in a large Swedish cohort of RA patients.

Results

The murine monoclonal anti‐COMP antibody 15A11 induced arthritis in naive mice. The crystal structure of the 15A11–P6 complex explained how the antibody could bind to COMP, which can be modulated by calcium ions. Moreover, serum IgG specific to the COMP P6 peptide and its citrullinated variants was detectable at significantly higher levels in RA patients compared to healthy controls and correlated with a higher disease activity score.

Conclusion

Our findings provide the structural basis for binding a pathogenic anti‐COMP antibody to cartilage. The recognized epitope can be citrullinated, and levels of antibodies to this epitope are elevated in RA patients and correlate with higher disease activity, implicating a pathogenic role of anti‐COMP antibodies in a subset of RA patients.

Rheumatoid Arthritis: Pathogenic Roles of Diverse Immune Cells

Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease associated with synovial tissue proliferation, pannus formation, cartilage destruction, and systemic complications. Currently, advanced understandings of the pathologic mechanisms of autoreactive CD4+ T cells, B cells, macrophages, inflammatory cytokines, chemokines, and autoantibodies that cause RA have been achieved, despite the fact that much remains to be elucidated. This review provides an updated pathogenesis of RA which will unveil novel therapeutic targets.

Increased susceptibility to organic dust exposure-induced inflammatory lung disease with enhanced rheumatoid arthritis-associated autoantigen expression in HLA-DR4 transgenic mice

Immunogenetic as well as environmental and occupational exposures have been linked to the development of rheumatoid arthritis (RA), RA-associated lung disease, and other primary lung disorders. Importantly, various inhalants can trigger post-translational protein modifications, resulting in lung autoantigen expression capable of stimulating pro-inflammatory and/or pro-fibrotic immune responses. To further elucidate gene-environment interactions contributing to pathologic lung inflammation, we exploited an established model of organic dust extract (ODE) exposure with and without collagen-induced arthritis (CIA) in C57BL/6 wild type (WT) versus HLA-DR4 transgenic mice. ODE-induced airway infiltration driven by neutrophils was significantly increased in DR4 versus WT mice, with corresponding increases in bronchoalveolar lavage fluid (BALF) levels of TNF-⍺, IL-6, and IL-33. Lung histopathology demonstrated increased number of ectopic lymphoid aggregates comprised of T and B cells following ODE exposure in DR4 mice. ODE also induced citrullination, malondialdehyde acetaldehyde (MAA) modification, and vimentin expression that co-localized with MAA and was enhanced in DR4 mice. Serum and BALF anti-MAA antibodies were strikingly increased in ODE-treated DR4 mice. Coupling ODE exposure with Type II collagen immunization (CIA) resulted in similarly augmented pro-inflammatory lung profiles in DR4 mice (relative to WT mice) that was accompanied by a profound increase in infiltrating lung CD4⁺ and CD8⁺ T cells as well as CD19⁺CD11b⁺ autoimmune B cells. Neither modeling strategy induced significant arthritis. These findings support a model in which environmental insults trigger enhanced post-translational protein modification and lung inflammation sharing immunopathological features with RA-associated lung disease in the selected immunogenetic background of HLA-DR4 mice.

Etiology and Risk Factors for Rheumatoid Arthritis: A State-of-the-Art Review

Rheumatoid arthritis (RA) is the most common systemic inflammatory rheumatic disease. It is associated with significant burden at the patient and societal level. Extensive efforts have been devoted to identifying a potential cause for the development of RA. Epidemiological studies have thoroughly investigated the association of several factors with the risk and course of RA. Although a precise etiology remains elusive, the current understanding is that RA is a multifactorial disease, wherein complex interactions between host and environmental factors determine the overall risk of disease susceptibility, persistence and severity. Risk factors related to the host that have been associated with RA development may be divided into genetic; epigenetic; hormonal, reproductive and neuroendocrine; and comorbid host factors. In turn, environmental risk factors include smoking and other airborne exposures; microbiota and infectious agents; diet; and socioeconomic factors. In the present narrative review, aimed at clinicians and researchers in the field of RA, we provide a state-of-the-art overview of the current knowledge on this topic, focusing on recent progresses that have improved our comprehension of disease risk and development.

Rheumatoid Arthritis in Silica-Exposed Workers

Few studies have examined rheumatoid arthritis (RA) risk and severity in Korean workers exposed to silica. We compared the hospitalization risk of RA between silica-exposed workers and the general Korean population. The study cohort consisted of male workers exposed to silica who had undergone at least one silica-associated special medical examination between 1 January 2000 and 31 December 2004 (N = 149,948). The data were from the Korea Occupation Safety and Health Agency. RA morbidity based on hospital admission records was estimated from 2000 to 2005 using the Korea National Health Insurance Service claims data. The standardized admission ratio (SAR) was calculated by dividing the observed number of admissions in silica-exposed workers by the expected number of admissions in the general reference population. For the sum of “Seropositive rheumatoid arthritis” (M05) and “Other rheumatoid arthritis” (M06), the SAR was higher in the silica-exposed group (1.34, 95% CI 1.08–1.64). For M05, workers with <10 years of silica exposure had a significantly higher SAR (2.54, 95% CI 1.10–5.01) than the general population. More silica-exposed workers without a diagnosis of pneumoconiosis were hospitalized for RA than the general population. Our analysis reaffirms the link between silica exposure and RA and suggests that the severity of RA is increased by silica. Further studies of silica-exposed workers with longer follow-up are needed.

Nanotechnology as a promising platform for rheumatoid arthritis management: Diagnosis, treatment, and treatment monitoring

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that develops in about 5 per 1000 people. Over the past years, substantial progresses in knowledge of the disease's pathophysiology, effective diagnosis methods, early detection, and efficient treatment strategies have been made. Notably, nanotechnology has emerged as a game-changer in the efficacious management of many diseases, especially for RA. Joint replacement, photothermal therapy (PTT), photodynamic therapy (PDT), RA diagnosis, and treatment monitoring are nano-based avenues in RA management. Here, we present a brief overview of the pathogenesis of RA, risk factors, conventional diagnostic methods and treatment approaches, and then discuss the role of nanomedicine in RA diagnosis, treatment, and treatment monitoring with an emphasis on functional characteristics distinctive from other RA therapeutics.

Silica Dust Exposure Increases Risk for Rheumatoid Arthritis: A Swedish National Registry Case-Control Study

OBJECTIVE

Rheumatoid arthritis (RA) is an inflammatory disease with unknown etiology. This study examines if silica dust exposure increases the risk for seropositive and seronegative RA.

METHODS

A nationwide registry case-control study was conducted that included all cases of RA in Sweden between 2005 and 2016. In total, 31,139 cases with two matched controls were included. A JEM was used to estimate exposure.

RESULTS

Silica dust exposure was associated with a statistically significant increase in odds ratio (OR) for seropositive (OR 1.22, 95% CI 1.05 to 1.40) and seronegative (OR 1.23, 95% CI 1.04 to 1.46) RA among men.

CONCLUSION

This study found an increased OR for RA in silica-exposed men. The OR was equal for seropositive and seronegative RA. These findings further support the hypothesis that silica dust may be a trigger for RA.

Enhancing extracellular vesicles for therapeutic treatment of arthritic joints

Extracellular vesicles are small membrane-derived packages of information that are released from virtually all cell types. These nano-packages contain regulatory material including proteins, lipids, mRNA and microRNA and are a key mechanism of paracellular communication within a given microenvironment. Encompassed with a lipid bilayer, these organelles have been attributed numerous roles in regulating both physiological and pathological functions. Herein, we describe the role of EVs in the context of Rheumatoid and Osteoarthritis and explore how they could be harnessed to treat inflammatory and degenerative joint conditions. These structures offer a promising therapeutic strategy for treating musculoskeletal diseases due to their bioactive content, stability, small size and intrinsic ability to enter the avascular cartilage, a notoriously challenging tissue to target. We also discuss how EVs can be manipulated to load therapeutic cargo or present additional targeting moieties to enhance their beneficial actions and tissue regenerative properties.

The impact of airborne endotoxin exposure on rheumatoid arthritis-related joint damage, autoantigen expression, autoimmunity, and lung disease

Airborne biohazards are risk factors in the development and severity of rheumatoid arthritis (RA) and RA-associated lung disease, yet the mechanisms explaining this relationship remain unclear. Lipopolysaccharide (LPS, endotoxin) is a ubiquitous inflammatory agent in numerous environmental and occupational air pollutant settings recognized to induce airway inflammation. Combining repetitive LPS inhalation exposures with the collagen induced arthritis (CIA) model, DBA1/J mice were assigned to either: sham (saline injection/saline inhalation), CIA (CIA/saline), LPS (saline/LPS 100 ng inhalation), or CIA + LPS for 5 weeks. Serum anti-citrullinated (CIT) protein antibody (ACPA) and anti-malondialdehyde-acetaldehyde (MAA) antibodies were strikingly potentiated with co-exposure (CIA + LPS). CIT- and MAA-modified lung proteins were increased with co-exposure and co-localized across treatment groups. Inhaled LPS exacerbated arthritis with CIA + LPS > LPS > CIA versus sham. Periarticular bone loss was demonstrated in CIA and CIA + LPS but not in LPS alone. LPS induced airway inflammation and neutrophil infiltrates were reduced with co-exposure (CIA + LPS). Potentially signaling transition to pro-fibrotic processes, there were increased infiltrates of activated CD11c+CD11b+ macrophages and transitioning CD11c+CD11bint monocyte-macrophage populations with CIA + LPS. Moreover, several lung remodeling proteins including fibronectin and matrix metalloproteinases as well as complement C5a were potentiated with CIA + LPS compared to other treatment groups. IL-33 concentrations in lung homogenates were enhanced with CIA + LPS with IL-33 lung staining driven by LPS. IL-33 expression was also significantly increased in lung tissues from patients with RA-associated lung disease (N = 8) versus controls (N = 7). These findings suggest that patients with RA may be more susceptible to developing interstitial lung disease following airborne biohazard exposures enriched in LPS.

Inorganic Dust Exposure During Military Service as a Predictor of Rheumatoid Arthritis and Other Autoimmune Conditions

OBJECTIVE

Rheumatoid arthritis (RA) and other autoimmune (AI) conditions are associated with inorganic dust exposure. Many military activities are likely to entail inorganic dust exposures. We wished to identify associations between prior military dust exposure and RA and other AI conditions.

METHODS

We studied persons from a roster of Army, Navy, Air Force, or Marine Corps personnel who had served in Operation Enduring Freedom and Operations Iraqi Freedom and New Dawn. We linked military occupational codes to a job exposure matrix assigning dust exposure likelihood. We used the Veterans Affairs Health Care System (VAHCS) electronic health care records to identify cases of RA, systemic lupus erythematosus (SLE), systemic sclerosis (SSc), vasculitis, and inflammatory myositis. Generalized estimating equations modeled risk of RA and other AI conditions associated with dust exposure, taking into account military service branch, age at first VAHCS encounter, sex, race/ethnicity, smoking status, and years of military service.

RESULTS

Of 438 086 veterans (68% ever-smokers), 44% were classified with likely or somewhat likely dust exposure. Cases included 1139 cases with RA, 467 cases with SLE, and 180 cases with other AI diseases (SSc, vasculitis, or inflammatory myositis). Military dust exposure was associated with increased odds of RA (odds ratio [OR] = 1.10; 95% confidence interval [CI] = 1.003-1.20) and increased odds of SSc, vasculitis, or inflammatory myositis (OR = 1.23; 95% CI = 1.14-1.34) but was protective for SLE (OR = 0.81; 95% CI = 0.76-0.88).

CONCLUSION

Dust exposure during past military service comprises an occupational and environmental risk factor for RA and other AI diseases. This is potentially relevant for prevention activities.

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.

Systematic Review and Meta-analysis on the Association of Occupational Exposure to Free Crystalline Silica and Rheumatoid Arthritis

• Occupational exposure to free crystalline silica and tobacco smoking are associated with an increased risk rheumatoid arthritis, with the evidence of an interaction in seropositive subjects.

• Further studies in the field are needed to support such association

We carried out a systematic search for all published epidemiological studies concerning the association between occupational exposure to free crystalline silica (FCS) and subsequent development of rheumatoid arthritis (RA). A meta-analysis was conducted on relevant studies. We searched PubMed and Embase, search engines, for original articles published (from 1960 to November 2019) in any language. In addition, we also searched reference lists of included studies manually for additional relevant articles. Finally, twelve studies were included in the meta-analysis (seven case-control cases and five cohort studies). The odds risks and 95% confidence interval (CI) were calculated using a random effect meta-analysis. A primary meta-analysis (using a random effect model)—regarding RA risk in subjects exposed to FCS—yelled to an overall OR of 1.94 (95% CI 1.46–2.58). We also conducted three further meta-analysis, taking into account the presence of autoantibodies (anti-RF or anti-ACPA) and smoking habits and found a significant association between FCS and RA in both seropositive and seronegative subjects (OR 1.74, 95% CI 1.35–2.25 and OR 1.23, 95% CI 1.06–1.4, respectively) and in seropositive subjects which were smokers (OR 3.30, 95% CI 2.40–4.54). The studies that have investigated the association between RA and occupatational exposure to FCS are still scarce and the heterogeneity between the studies remains high. Some critical limitations have been identified within studies, among which, the methods for assessing exposure stand out. Although with due caution, our results confirm the hypothesis of an association between occupational exposure to FCS and RA development. There was an interaction between FCS and tobacco smoking in RA seropositive workers.

Sexual Dimorphism in the Expression of Pain Phenotype in Preclinical Models of Rheumatoid Arthritis

Rheumatoid arthritis is one of most frequent rheumatic diseases, affecting around 1% of the population worldwide. Pain impacting the quality of life for the patient with rheumatoid arthritis, is often the primary factor leading them to seek medical care. Although sex-related differences in humans and animal models of rheumatoid arthritis are described, the correlation between pain and sex in rheumatoid arthritis has only recently been directly examined. Here we review the literature and explore the mechanisms underlying the expression of the pain phenotype in females and males in preclinical models of rheumatoid arthritis.

Inhalants other than personal cigarette smoking and risk for developing rheumatoid arthritis

PURPOSE OF REVIEW

The current review summarizes the current evidence on inhalants other than personal cigarette smoking and risk for developing rheumatoid arthritis (RA).

RECENT FINDINGS

Personal cigarette smoking has been implicated as an environmental risk factor for seropositive RA, perhaps by inducing autoimmunity at pulmonary mucosa. Since many patients with RA are nonsmokers, other inhalants are being investigated as potential RA risk factors. Recent case-control and cohort studies have investigated passive cigarette smoking, air pollution, inhalant-related occupations, silica, pesticides, household environment, and allergic inhalants as inhalant exposures for RA risk. Inhalant-related occupations and silica inhalants have the most consistent evidence for associations with increased RA risk. However, most studies relied on retrospective designs and had limited ability to adjust for personal cigarette smoking or investigate associations among nonsmokers.

SUMMARY

Several inhalants other than personal cigarette smoking may be associated with increased risk for developing RA. These results support the hypothesis that inhalants, pulmonary mucosal inflammation, and RA pathogenesis may be linked. Future studies are needed to firmly establish the independence of these findings from personal cigarette smoking and to determine the specific inhalants and biologic mechanisms related to RA pathogenesis.

Association between traffic-related air pollution and hospital readmissions for rheumatoid arthritis in Hefei, China: A time-series study

Air pollution is an important risk factor for autoimmune diseases, but its association with the recurrence of rheumatoid arthritis (RA) remains unclear so far. This study aimed to investigate the short-term association between traffic-related air pollutants and hospital readmissions for RA in Hefei, China. Data on daily hospital readmissions for RA and traffic-related air pollutants, including particulate matter (PM_2.5 and PM₁₀), nitrogen dioxide (NO₂), and carbon monoxide (CO), from 2014 to 2018 were retrieved. A time-series approach using generalized linear regression model was employed. The analysis was further stratified by sex, age and season. A total of 1153 readmissions for RA were reported during the study period. A significant association between high-concentration PM_2.5 (90th percentile) and RA readmissions was observed on lag1 (relative risk (RR) = 1.09, 95% confidence interval (CI): 1.01-1.19) and lasted until lag3 (RR = 1.06, 95%CI: 1.01-1.12). From lag2 to lag5, high-concentration NO₂ (90th percentile) was associated with increased risk of RA readmissions, with the highest RR observed at lag 4 (1.11, 95%CI: 1.05-1.17). Stratified analyses indicated that females and the elderly appeared to be more vulnerable to high-concentration PM_2.5 and NO₂ exposure. High-concentration PM_2.5 and NO₂ in cold seasons were consistently significantly associated with increased risk of RA readmissions. Exposure to high-concentration PM_2.5 and NO₂ was associated with increased risk of RA readmissions. Protective measures against the exposure to high-concentration PM_2.5 and NO₂ should be taken to reduce the recurrence risk in RA patients, especially in females, the elderly and during cold seasons.

Rheumatological Diseases in Denim Sandblasters with Silicosis: What Should Pulmonologists Look for?

OBJECTIVE

Silica exposure is not only the cause of silicosis, also associated rheumatological diseases like rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and systemic sclerosis (SSc). This report will reveal the rheumatological diseases of silicosis patients who were exposed to silica while working as denim sandblasters. Additionally, we will describe some clinical and laboratory findings that will help pulmonologist suspect, recognize and manage rheumatological diseases related to silica exposure in patients with silicosis.

MATERIAL AND METHODS

We reviewed the records of 142 sandblasters diagnosed with silicosis and found ten silicosis cases who also had rheumatological diseases between the years 2009 and 2017. The occupational characteristics, serological, functional and radiological data, were collected for patients of silicosis with rheumatological diseases.

RESULTS

Ten silicosis patients with concomitant rheumatological diseases were found. Six patients among our cases had diagnosed SSc (4.2%), three of them had RA (2.1%), and one of them was being monitored for SLE (0.7%). The mean silica exposure time of the cases was 4.3±1.9 years (min: 1 max: 8). We also found elevated LD, sedimentation and CRP levels in our cases.

CONCLUSION

It should be kept in mind that, in silicosis cases with arthralgia, joint tenderness or sclerosis at the fingertips may be indicative of rheumatological diseases related to silica exposure, and in these cases, the unexplained elevations of sedimentation and CRP levels may also be a result of silica-induced rheumatological diseases.

Environment and Lifestyle: Their Influence on the Risk of RA

Background: Rheumatoid arthritis (RA) is a complex disease in which environmental agents are thought to interact with genetic factors that lead to triggering of autoimmunity. Methods: We reviewed environmental, hormonal, and dietary factors that have been suggested to be associated with the risk of RA. Results: Smoking is the most robust factor associated with the risk of RA, with a clear gene–environment interaction. Among other inhalants, silica may increase the risk of RA in men. There is less evidence for pesticides, pollution, and other occupational inhalants. Regarding female hormonal exposures, there is some epidemiological evidence, although not consistent in the literature, to suggest a link between hormonal factors and the risk of RA. Regarding dietary factors, available evidence is conflicting. A high consumption of coffee seems to be associated with an increased risk of RA, whereas a moderate consumption of alcohol is inversely associated with the risk of RA, and there is less evidence regarding other food groups. Dietary pattern analyses (Mediterranean diet, the inflammatory potential of the diet, or diet quality) suggested a potential benefit of dietary modifications for individuals at high risk of RA. Conclusion: To date, smoking and silica exposure have been reproducibly demonstrated to trigger the emergence of RA. However, many other environmental factors have been studied, mostly with a case-control design. Results were conflicting and studies rarely considered potential gene–environment interactions. There is a need for large scale prospective studies and studies in predisposed individuals to better understand and prevent the disease and its course.

Systemic Autoimmune Disease Among Adults Exposed to the September 11, 2001 Terrorist Attack

Objective

Autoimmune disease is an emerging condition among persons exposed to the September 11, 2001 attack on the World Trade Center (WTC). Components of the dust cloud resulting from the collapse of the WTC have been associated with development of a systemic autoimmune disease, as has posttraumatic stress disorder (PTSD). We undertook this study to determine whether dust exposure and PTSD were associated with an increased risk of systemic autoimmune disease in a 9/11‐exposed cohort.

Methods

Among 43,133 WTC Health Registry enrollees, 2,786 self‐reported having a post‐9/11 systemic autoimmune disease. We obtained informed consent to review medical records to validate systemic autoimmune disease diagnoses for 1,041 enrollees. Diagnoses of systemic autoimmune diseases were confirmed by classification criteria, rheumatologist diagnosis, or having been prescribed systemic autoimmune disease medication. Controls were enrollees who denied having an autoimmune disease diagnosis (n = 37,017). We used multivariable log‐binomial regression to examine the association between multiple 9/11 exposures and risk of post‐9/11 systemic autoimmune disease, stratifying by responders (rescue, recovery, and clean‐up workers) and community members (e.g., residents, area workers).

Results

We identified 118 persons with systemic autoimmune disease. Rheumatoid arthritis was most frequent (n = 71), followed by Sjӧgren's syndrome (n = 22), systemic lupus erythematosus (n = 20), myositis (n = 9), mixed connective tissue disease (n = 7), and scleroderma (n = 4). Among 9/11 responders, those with intense dust cloud exposure had almost twice the risk of systemic autoimmune disease (adjusted risk ratio 1.86 [95% confidence interval 1.02–3.40]). Community members with PTSD had a nearly 3‐fold increased risk of systemic autoimmune disease.

Conclusion

Intense dust cloud exposure among responders and PTSD among community members were associated with a statistically significant increased risk of new‐onset systemic autoimmune disease. Clinicians treating 9/11 survivors should be aware of the potential increased risk of systemic autoimmune disease in this population.

The association Between Occupational Exposure to silica and Risk of Developing Rheumatoid Arthritis: A Meta-Analysis

Background

Rheumatoid arthritis (RA) is an autoimmune disease with systemic inflammatory arthritis. This meta-analysis was conducted to examine the association between occupational exposure to silica and the risk of developing RA among different workers.

Methods

In this meta-analysis, we searched relevant published studies using major electronic databases including Scopus, PubMed, ISI Web of Science, and Google Scholar search engine up to October 2019, and the references of retrieved articles were also checked for further possible sources. A random-effects model was used to account for heterogeneity among the results of the studies using the pooled odds ratios (ORs) and their 95% confidence intervals (CIs). The Q-statistic and I² tests were calculated to assess heterogeneity between the studies.

Results

The pooled calculation of OR indicated a significant association between occupational exposure to silica and risk of developing RA among different workers (OR = 2.59, 95% CI = 1.73 to 3.45). In addition, the pooled estimates of OR in smokers were statistically significant (OR = 2.49, 95% CI = 1.13 to 3.86).

Conclusions

The findings of the present study reveal that occupational exposure to silica may be associated with increased risk of developing RA.

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.

T Cell Dysregulation in Non-silicotic Silica Exposed Workers: A Step Toward Immune Tolerance Breakdown

Background: Chronic silica exposure can lead to silicosis, complicated or not by autoimmune diseases (AID). The pathophysiology of silica-induced AID remains not fully understood, especially immune mechanisms that may develop in patients without yet established silicosis. We conducted a prospective clinical study to analyze the impact of crystalline silica (CS) on T cell phenotype and regulatory T cells (Tregs) frequency, as well as on auto-antibodies development in non-silicotic workers exposed to CS.

Methods: Workers with moderate to high exposure level to CS and aged between 30 and 60 years-old were considered for inclusion. Peripheral blood mononuclear cells were analyzed by flow cytometry. Auto-antibodies were screened in serum by immunofluorescence. Blood from 42 and 45 healthy subjects (HC) was used as control for T cell phenotype and serum analyses, respectively.

Results: Among the 63 included workers exposed to CS, 55 had full data available and were analyzed. Ten were exposed to CS for <5 years, 18 for 5–10 years and 27 for more than 10 years. The frequency of Tregs (CD4⁺CD25⁺CD127⁻FoxP3⁺) was significantly lower in CS exposed workers as compared to HC. We found an increased expression of the activation marker HLA-DR on T cells (CD3⁺, CD4⁺, and CD8⁺) of CS exposed workers as compared to HC. Tregs to activated T cells ratio was also lower in exposed subjects. In the latter, HLA-DR expression level and Tregs frequency were significantly associated with CS exposure duration. Serum autoantibody detection was significantly higher in CS exposed workers as compared to HC. Especially, among workers exposed more than 10 years, antinuclear antibodies and ANCA were detected in 44 and 22% among them, as compared to 5 and 2.5% in HC, respectively.

Conclusion: This work shows that CS exposure is associated with a decrease of Tregs frequency, an increase of T cell activation status, and a tolerance breakdown against auto-antigens. These results show that alterations of the T cell compartment can be detected early over the course of CS exposure, preceding silicosis development or AID onset.

Occupational exposure to organic dusts and risk of developing rheumatoid arthritis: findings from a Swedish population-based case-control study

Objectives

We estimated the association between occupational exposures to five different organic dusts: wood, animal, paper, textile and flour dust and the risk of developing rheumatoid arthritis (RA).

Methods

This population-based case–control study analysed 12 582 incident cases and 129 335 controls. Participants were identified from national public authority and quality registers. Census data on occupations were collected 1960–2010 and we estimated the exposure to organic dust with the help of job-exposure matrices. We used logistic regression to assess the OR of seropositive or seronegative RA. Estimates were adjusted for the matching variables (sex, county, age and index year), education and occupational silica exposure.

Results

Exposure to animal dust was associated with an increased risk of RA among both men and women. The OR was 1.2 (95% CI=1.1 to 1.4) for seropositive RA and 1.3 (95% CI=1.1 to 1.5) for seronegative RA among ever exposed participants compared with unexposed. The risk increased with duration of exposure for seropositive RA, and participants who had been exposed in five or more censuses had an OR of 1.6 (95% CI=1.1 to 2.2, p for trend=0.003). Exposure to textile dust also generated a significant dose–response relationship for seropositive RA (p for trend=0.014). We detected no association between exposure to wood, paper or flour dust and risk of RA.

Conclusions

Overall, exposure to animal dust and textile dust was associated with an increased risk of developing RA. These observations give further support to the notion that airborne exposures are involved in the aetiology of RA.