Serum immunoglobulins, rheumatoid factor, and pneumoconiosis in coal miners with rheumatoid arthritis

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.

Association of Silicosis and Dermatomyositis: Case Report and Literature Review

The association between silicosis and autoimmune diseases is not uncommon. Silicosis is well correlated with rheumatoid arthritis and systemic lupus erythematosus. However, cases of dermatomyositis associated with silicosis are relatively understudied. We report a case of a 59-year-old man with a history of cardiac, respiratory, and systemic symptoms for the duration of a year, who present to the ER with acute dyspnea, fever, chest pain, and dry cough, and was diagnosed with silicosis and dermatomyositis. In this case report, we discuss the workup done in order to reach the diagnosis, as well as the pathological mechanism that might have led to the emergence of those two entities in the same patient.

Prevalence of Arthritis and Rheumatoid Arthritis in Coal Mining Counties of the United States

OBJECTIVE

Exposure to inhaled mineral dust, in particular silica, is associated with increased odds of rheumatoid arthritis (RA) and other autoimmune diseases. We studied the association of RA with work-related coal and silica exposure in the Appalachian region of the US.

METHODS

We carried out a random-digit dialed telephone survey in selected counties in Appalachia that had elevated coal workers' pneumoconiosis mortality. Our study cohort included men ages ≥50 with any employment history, and we assessed exposure to coal mining employment, other work-related dust, and ergonomic factors. We ascertained self-reported physician diagnosis of any arthritis and of RA with glucocorticoid treatment. We used multivariable logistic regression analysis to estimate the odds ratios (ORs) and associated population attributable fraction (PAF) estimates.

RESULTS

Among the 973 men who met study entry criteria (mean ± SD ages 66 ± 10 years; 54% ever smokers), 266 (27%) reported coal mining work and 189 (19%) reported other work-related silica exposure. There were 517 men (53%), who reported any arthritis and 112 (12%) whose disease met the study definition of RA. Adjusting for covariates, coal mining was associated with elevated odds of RA (OR 3.6 [95% confidence interval (95% CI) 2.1-6.2]), which accounted for a PAF of 33% (95% CI 26-40%) of the men studied. For any arthritis, the coal mining-associated OR was 2.3 (95% CI 1.6-3.2), with an associated PAF of 20% (95% CI 14-25%).

CONCLUSION

In this population of older males living in a coal mining region, we estimated that 20% of arthritis and 33% of RA may be attributable to coal mining work.

Does dust-associated pulmonary alveolar proteinosis represent an autoimmune disorder?

The role of autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF) in the development of secondary pulmonary alveolar proteinosis (PAP) in patients exposed to occupational and environmental dust remains unclear. Herein, we describe two cases of secondary PAP who had GM-CSF antibodies and absence of STAT5 phosphorylation index, suggestive of a potential relationship between the appearance of GM-CSF antibodies and environmental dust exposure. However, whether the presence of GM-CSF antibodies is a part of the pathological process or represents an epiphenomenon is currently unknown. In this report, we would like to present two cases supporting these new data and briefly discuss the possible role of autoimmune mechanisms in the development of secondary PAP. Am. J. Ind. Med. 60:591-597, 2017. © 2017 Wiley Periodicals, Inc.

Silicosis and coal workers' pneumoconiosis

Exposure to coal mine dust and/or crystalline silica results in pneumoconiosis with initiation and progression of pulmonary fibrosis. This review presents characteristics of simple and complicated coal workers' pneumoconiosis (CWP) as well as pathologic indices of acute and chronic silicosis by summarizing results of in vitro, animal, and human investigations. These results support four basic mechanisms in the etiology of CWP and silicosis: a) direct cytotoxicity of coal dust or silica, resulting in lung cell damage, release of lipases and proteases, and eventual lung scarring; b) activation of oxidant production by pulmonary phagocytes, which overwhelms the antioxidant defenses and leads to lipid peroxidation, protein nitrosation, cell injury, and lung scarring; c) activation of mediator release from alveolar macrophages and epithelial cells, which leads to recruitment of polymorphonuclear leukocytes and macrophages, resulting in the production of proinflammatory cytokines and reactive species and in further lung injury and scarring; d) secretion of growth factors from alveolar macrophages and epithelial cells, stimulating fibroblast proliferation and eventual scarring. Results of in vitro and animal studies provide a basis for proposing these mechanisms for the initiation and progression of pneumoconiosis. Data obtained from exposed workers lend support to these mechanisms.

Multiple clinical and biological autoimmune manifestations in 50 workers after occupational exposure to silica

OBJECTIVES

A self referred group of four workers from a factory producing scouring powder with a high silica content showed a surprisingly high number of features compatible with a connective tissue disease. Further subjects working at the same factory were subsequently studied to evaluate the relation between this exposure and the development of autoimmune processes.

METHODS

A total of 50 subjects (44 women, six men; mean (SD) age 43.7 (5.5) years; mean duration of employment 6.1 years) underwent a prospective study including clinical history and physical examination, an immunobiological study, HLA typing, radiological and functional oesophageal and respiratory examination, ophthalmological examination, and isotopic testing of salivary glands.

RESULTS

Symptoms of a systemic illness were present in 32 (64%) subjects: six with Sjögren's syndrome; five with the criteria for systemic sclerosis; three with systemic lupus erythematosus (SLE); five with an 'overlap syndrome'; and 13 with undifferentiated findings not meeting the criteria for a defined disease. Antinuclear antibodies were present in 36 (72%) subjects; four had antibodies to native DNA, including two subjects with SLE, one with systemic sclerosis associated with secondary Sjögren's syndrome, and one with overlap syndrome. Anticentromere antibodies were not detected. The frequency of HLA-DR3 was increased in the clinically affected subjects, but did not reach statistical significance.

CONCLUSIONS

This descriptive study emphasises the high probability of workers occupationally exposed to silica developing a multiple spectrum of clinical and serological autoimmune manifestations.