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

Occupational dust and chemical exposures and the development of autoimmune rheumatic diseases

Although the association between certain occupational exposures and the development of autoimmune rheumatic disease was first described over a century ago, this association has only become more widely recognized in the past 10 years because of the use of high-silica-content engineered stone in construction and home renovation. There is now a substantial and growing body of evidence that occupational dust and chemical exposure, be it through mining, stonemasonry, building or other trades, increases the risk of various systemic autoimmune rheumatic diseases (SARDs) including rheumatoid arthritis and systemic sclerosis. Although the pathogenic mechanisms of silica-induced autoimmunity are not fully elucidated, it is thought that alveolar macrophage ingestion of silica and the ensuing phagosomal damage is an initiating event that ultimately leads to production of autoantibodies and immune-mediated tissue injury. The purportedly causal association between occupational exposure to chemicals, such as organic solvents, and an increased risk of SARDs is less frequently recognized compared with silica dust, and its immunopathogenesis is less well understood. An appreciation of the importance of occupational dust and chemical exposures in the development of SARDs has implications for workplace health and safety regulations and offers a unique opportunity to better understand autoimmune disease pathogenesis and implement preventative strategies.

Airborne culprits: A comprehensive review of PM, silica, and TCDD in autoimmune diseases

Autoimmune diseases (ADs) are immunological disorders arising from the breakdown of immune tolerance, influenced by various internal and external factors. Persistent exposure to environmental factors, particularly air pollution, is linked to systemic inflammation, oxidative stress, and apoptosis, which contribute to the development of ADs. This review examines the impact of air pollutants, including particulate matter, silica, and TCDD, by analyzing epidemiological studies, animal models, and in vitro assays. It focuses on how air pollution disrupts the immune system, leading to apoptosis, increased oxidative stress, cytokine production, autoantigen release, autoantibody production, and autoreactivity, which are particularly significant in ADs like rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, and systemic sclerosis. In essence, this approach aims to provide a profound understanding of how exposure to air pollution can initiate or contribute to ADs, offering potential avenues for more targeted preventive and therapeutic strategies.

Trends and future projections of incidence rate and mortality of rheumatoid arthritis in China: a systematic analysis based on GBD 2021 data

This study aims to evaluate the trends in rheumatoid arthritis (RA) in China from 1990 to 2021 by analyzing data from the Global Burden of Disease (GBD) 2021 study and to predict the trends for the next 25 years. Age-standardized incidence rates (ASIR) and age-standardized mortality rates (ASMR) were calculated, and the estimated annual percentage change was used to illustrate differences in age distribution among various populations. Age-period-cohort (APC) analysis and Bayesian APC (BAPC) models were employed to forecast the burden of RA in China from 2022 to 2046. From 1990 to 2021, the ASIR of RA in China increased from 11.6 to 13.7, with a significantly higher ASIR in females than in males. Despite the increase in incidence, the ASMR related to RA decreased from 0.7 to 0.5. Predictions using the BAPC model indicate that the incidence of RA will continue to rise, with an expected ASIR of approximately 16.4 by 2046, and the total number of RA cases is projected to reach around 342,000. In terms of mortality, the ASMR is expected to decline to 0.3 by 2046, although the total number of deaths might reach about 40,000. The incidence of RA in China has significantly increased over the past 30 years. Although the incidence rate and the total number of RA cases may continue to rise in the future, the mortality rate of RA has been consistently declining. Key Points • Over the past 30 years, the incidence of RA in China has significantly increased; although the incidence rate and total number of cases may continue to rise, the mortality rate has been consistently declining.

Exposome and unhealthy aging: environmental drivers from air pollution to occupational exposures

The aging population worldwide is facing a significant increase in age-related non-communicable diseases, including cardiovascular and brain pathologies. This comprehensive review paper delves into the impact of the exposome, which encompasses the totality of environmental exposures, on unhealthy aging. It explores how environmental factors contribute to the acceleration of aging processes, increase biological age, and facilitate the development and progression of a wide range of age-associated diseases. The impact of environmental factors on cognitive health and the development of chronic age-related diseases affecting the cardiovascular system and central nervous system is discussed, with a specific focus on Alzheimer's disease, Parkinson's disease, stroke, small vessel disease, and vascular cognitive impairment (VCI). Aging is a major risk factor for these diseases. Their pathogenesis involves cellular and molecular mechanisms of aging such as increased oxidative stress, impaired mitochondrial function, DNA damage, and inflammation and is influenced by environmental factors. Environmental toxicants, including ambient particulate matter, pesticides, heavy metals, and organic solvents, have been identified as significant contributors to cardiovascular and brain aging disorders. These toxicants can inflict both macro- and microvascular damage and many of them can also cross the blood-brain barrier, inducing neurotoxic effects, neuroinflammation, and neuronal dysfunction. In conclusion, environmental factors play a critical role in modulating cardiovascular and brain aging. A deeper understanding of how environmental toxicants exacerbate aging processes and contribute to the pathogenesis of neurodegenerative diseases, VCI, and dementia is crucial for the development of preventive strategies and interventions to promote cardiovascular, cerebrovascular, and brain health. By mitigating exposure to harmful environmental factors and promoting healthy aging, we can strive to reduce the burden of age-related cardiovascular and brain pathologies in the aging population.

Airborne occupational exposures associated with pulmonary sarcoidosis: a systematic review and meta-analysis

The aetiology and pathophysiology of sarcoidosis is ill defined-current hypotheses centre on complex genetic-immune-environmental interactions in an individual, triggering a granulomatous process. The aim of this systematic review is to define and describe which airborne occupational exposures (aOE) are associated with and precede a diagnosis of pulmonary sarcoidosis. The methodology adopted for the purpose was systematic review and meta-analyses of ORs for specified aOE associated with pulmonary sarcoidosis (DerSimonian Laird random effects model (pooled log estimate of OR)). Standard search terms and dual review at each stage occurred. A compendium of aOE associated with pulmonary sarcoidosis was assembled, including mineralogical studies of sarcoidosis granulomas. N=81 aOE were associated with pulmonary sarcoidosis across all study designs. Occupational silica, pesticide and mould or mildew exposures were associated with increased odds of pulmonary sarcoidosis. Occupational nickel and aluminium exposure were associated with a non-statistically significant increase in the odds of pulmonary sarcoidosis. Silica exposure associated with pulmonary sarcoidosis was reported most frequently in the compendium (n=33 studies) and was the most common mineral identified in granulomas. It was concluded that aOE to silica, pesticides and mould or mildew are associated with increased odds of pulmonary sarcoidosis. Equipoise remains concerning the association and relationship of metal dusts with pulmonary sarcoidosis.

Modifiable risk factors linked to the development of rheumatoid arthritis: evidence, immunological mechanisms and prevention

Rheumatoid Arthritis (RA) is a common autoimmune disease that targets the synovial joints leading to arthritis. Although the etiology of RA remains largely unknown, it is clear that numerous modifiable risk factors confer increased risk to developing RA. Of these risk factors, cigarette smoking, nutrition, obesity, occupational exposures and periodontal disease all incrementally increase RA risk. However, the precise immunological mechanisms by which these risk factors lead to RA are not well understood. Basic and translational studies have provided key insights into the relationship between inflammation, antibody production and the influence in other key cellular events such as T cell polarization in RA risk. Improving our general understanding of the mechanisms which lead to RA will help identify targets for prevention trials, which are underway in at-risk populations. Herein, we review the modifiable risk factors that are linked to RA development and describe immune mechanisms that may be involved. We highlight the few studies that have sought to understand if modification of these risk factors reduces RA risk. Finally, we speculate that modification of risk factors may be an appealing avenue for prevention for some at-risk individuals, specifically those who prefer lifestyle interventions due to safety and economic reasons.

Polymer nanotherapeutics: A versatile platform for effective rheumatoid arthritis therapy

Rheumatoid arthritis is an aggressive and severely debilitating disorder that is characterized by joint pain and cartilage damage. It restricts mobility in patients, leaving them unable to carry out simple tasks. RA presents itself with severe lasting pain, swelling and stiffness in the joints and may cause permanent disability in patients. Treatment regimens currently employed for rheumatoid arthritis revolve around keeping clinical symptoms like joint pain, inflammation, swelling and stiffness at bay. The current therapeutic interventions in rheumatoid arthritis involve the use of non-steroidal anti-inflammatory drugs, glucocorticoids, disease-modifying anti-rheumatic drugs and newer biological drugs that are engineered for inhibiting the expression of pro-inflammatory mediators. These conventional drugs are plagued with severe adverse effects because of their higher systemic distribution, lack of specificity and higher doses. Oral, intra-articular, and intravenous routes are routinely used for drug delivery which is associated with decreased patient compliance, high cost, poor bioavailability and rapid systemic clearance. All these drawbacks have enticed researchers to create novel strategies for drug delivery, the main approach being nanocarrier-based systems. In this article, we aim to consolidate the remarkable contributions of polymeric carrier systems including microneedle technology and smart trigger-responsive polymeric carriers in the management of rheumatoid arthritis along with its detailed pathophysiology. This review also briefly describes the safety and regulatory aspects of polymer therapeutics.

Dusty trades and associated rheumatoid arthritis in a population-based study in the coal mining counties of Appalachia

OBJECTIVES

We previously showed increased coal mining-associated risk of rheumatoid arthritis (RA). Using additional survey data, we sought to delineate this risk further.

METHODS

We used data from two cross-sectional, random-digit-dial, population-based surveys (males;≥50 years) in selected counties in the Appalachian region of the inland, mid-Atlantic USA with elevated pneumoconiosis mortality. Surveys ascertained age, smoking, coal mining and non-coal silica exposure jobs. In a subset, we surveyed ergonomic exposures, scored by intensity. We queried diagnosis of RA, corticosteroid use, and, in a subset, use of disease modifying antirheumatic drugs (DMARDs). Multivariable logistic regression modelled RA risk (defined by glucocorticoid or DMARDs use) associated with coal mining employment, other silica exposure, smoking status, and age and ergonomic exposures.

RESULTS

We analysed data for 2981 survey respondents (mean age 66.6 years; 15% current, 44% ex-smokers). The prevalence of glucocorticoid-treated and DMARD-treated RA was 11% and 4%, respectively. Glucocorticoid-treated RA was associated with coal mining (OR 3.5; 95% CI 2.5 to 4.9) and non-coal mining silica exposure (OR 3.2; 95% CI 2.4 to 4.4). For DMARD-treated RA, the odds associated with coal mining and other silica remained elevated: OR 2.3 (95% CI 1.18, 4.5) and OR 2.7 (95% CI 1.51, 5.0), respectively. In the same model, the highest intensity ergonomic exposure also was associated with increased odds of RA (OR 4.3; 95% CI 1.96 to 9.6).

CONCLUSIONS

We observed a strong association between coal mining and other silica-exposing dusty trades and RA. Clinicians and insurers should consider occupational histories in the aetiology of RA.

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.