Systemic lupus erythematosus after heavy exposure to quartz dust in uranium mines: clinical and serological characteristics

Serum autoantibodies and exploratory molecular pathways in rural miners: A pilot study

Introduction

The Southwestern United States (SWUS) has an extensive history of coal and metal mining, including uranium (U) mining. Lung diseases, including but not limited to, lung cancer and pulmonary fibrosis, have been studied extensively in miners due to occupational, dust-related exposures. However, high-throughput autoimmune biomarkers are largely understudied in miners, despite the fact that ore miners, such as U-miners, are at an increased risk for the development of autoimmune diseases such as systemic sclerosis and systemic lupus erythematosus (SLE). Additionally, there are current gaps in knowledge regarding which signaling pathways may play a role in occupational exposure-associated autoimmunity.

Methods

Most current and former miners in the SWUS live close to their previous workplaces, in remote areas, with limited access to healthcare. In this pilot study, by leveraging a mobile clinical platform for patient care and clinical outreach, we recruited 44 miners who self-identified as either U (n = 10) or non-U miners (n = 34) and received health screenings. Serum IgG and IgM autoantibodies against 128 antigens were assessed using a high-throughput molecular technique, as a preliminary health screening opportunity.

Results

Even when adjusting for age as a covariate, there was a significant (p < 0.05) association between self-reported U-mining exposure and biomarkers including IgM alpha-actinin, histones H2B, and H4, myeloperoxidase (MPO) and myelin basic protein. However, adjusting for age did not result in significant associations for IgG autoantibody production in U-miners. Bioinformatic pathway analysis revealed several altered signaling pathways between IgM and IgG autoantibodies among both U and non-U miners.

Conclusions

Further research is warranted regarding the mechanistic connection between U-exposure and autoantibody development, especially regarding histone-related alterations and IgM autoantibody production.

The immunotoxicity of natural and depleted uranium: From cells to people

Uranium is a naturally occurring element found in the environment as a mixture of isotopes with differing radioactive properties. Enrichment of mined material results in depleted uranium waste with substantially reduced radioactivity but retains the capacity for chemical toxicity. Uranium mine and milling waste are dispersed by wind and rain leading to environmental exposures through soil, air, and water contamination. Uranium exposure is associated with numerous adverse health outcomes in humans, yet there is limited understanding of the effects of depleted uranium on the immune system. The purpose of this review is to summarize findings on uranium immunotoxicity obtained from cell, rodent and human population studies. We also highlight how each model contributes to an understanding of mechanisms that lead to immunotoxicity and limitations inherent within each system. Information from population, animal, and laboratory studies will be needed to significantly expand our knowledge of the contributions of depleted uranium to immune dysregulation, which may then inform prevention or intervention measures for exposed communities.

Hazardous dusts from the fabrication of countertop: a review

Artificial countertop materials, including solid surface composites (SSC) and engineered stone (ES) may pose significant pulmonary health risks for workers who manipulate them. These materials have rapidly become popular in the multibillion-dollar countertop industry, rivaling that of natural materials such as granite and marble due to their variety of desirable esthetic qualities and reduced costs. Both SSC and ES consist of a mineral substrate bound together in a polymer matrix. For SSC the mineral is about 70% aluminum trihydrate (ATH) while ES contains up to 95% crystalline silica by weight. Both materials emit airborne dusts when being manipulated with power tools during the fabrication process. Several deaths and dozens of cases of silicosis have been identified worldwide in workers who fabricate ES, while a single case of fatal pulmonary fibrosis has been associated with SCC dust exposure. This review examines the current state of knowledge for both SSC and ES regarding the composition, particle emission characteristics, workplace exposure data, particle constituent toxicity, and possible methods for reducing worker exposure.

Silica-associated systemic lupus erythematosus with lupus nephritis and lupus pneumonitis: A case report and a systematic review of the literature

INTRODUCTION

Several epidemiological studies have shown that silica exposure triggers the onset of systemic lupus erythematosus (SLE); however, the clinical characteristics of silica-associated SLE have not been well studied.

PATIENT CONCERNS

A 67-year-old man with silicosis visited a primary hospital because of a fever and cough. His respiratory condition worsened, regardless of antibiotic medication, and he was referred to our hospital.

DIAGNOSIS

The patient showed leukopenia, lymphopenia, serum creatinine elevation with proteinuria and hematuria, decreased serum C3 level, and was positive for anti-double stranded DNA antibody, anti-nuclear antibody, and direct Coombs test. He was diagnosed with SLE. Renal biopsy was performed, and the patient was diagnosed with lupus nephritis (class IV-G(A/C) + V defined by the International Society of Nephrology/Renal Pathology Society classification). Computed tomography revealed acute interstitial pneumonitis, bronchoalveolar lavage fluid showed elevation of the lymphocyte fraction, and he was diagnosed with lupus pneumonitis.

INTERVENTIONS

Prednisolone (50 mg/day) with intravenous cyclophosphamide (500 mg/body) were initiated.

OUTCOMES

The patient showed a favorable response to these therapies. He was discharged from our hospital and received outpatient care with prednisolone slowly tapered off. He had cytomegalovirus and herpes zoster virus infections during treatment, which healed with antiviral therapy.

REVIEW

We searched for the literature on sSLE, and selected 11 case reports and 2 population-based studies. The prevalence of SLE manifestations in sSLE patients were comparative to that of general SLE, particularly that of elderly-onset SLE. Our renal biopsy report and previous reports indicate that lupus nephritis of sSLE patients show as various histological patterns as those of general SLE patients. Among the twenty sSLE patients reported in the case articles, three patients developed lupus pneumonitis and two of them died of it. Moreover, two patients died of bacterial pneumonia, one developed aspergillus abscesses, one got pulmonary tuberculosis, and one developed lung cancer.

CONCLUSION

Close attention is needed, particularly for respiratory system events and infectious diseases, when treating patients with silica-associated SLE using immunosuppressive therapies.

Exposure to silicates and systemic autoimmune-related outcomes in rodents: a systematic review

BACKGROUND

Autoimmunity can result from the interplay between genetic background and effects of environmental and/or occupational exposure to hazardous materials. Several compounds, including silica dust, have been linked with systemic autoimmunity and systemic autoimmune diseases, based on epidemiological evidence. For asbestos, a strong link with systemic autoimmune diseases does not yet exist, however, several studies have documented features of autoimmunity following asbestos exposure. Even so, human studies are limited in their ability to identify and examine isolated exposures, making it difficult to demonstrate causation or to assess pathogenic mechanisms. Therefore, this systematic review examines the existing animal evidence regarding autoimmunity and exposure to silicates (silica and asbestos).

METHODS

PubMed and EMBASE were systematically searched for peer-reviewed studies examining systemic autoimmune disease-related outcomes after silicate exposure in rodents. Literature databases were searched up to September 2021 for studies written in English and where the full text was available. Search strings were established based on a PECO (Population, Exposure, Comparator, Outcome) format. After title, abstract, and full-text screening, thirty-four studies were identified for further analysis. Quality assessment through ToxR tool and qualitative analysis of the results was performed.

RESULTS

Although there was significant heterogeneity in the included studies in terms of exposure protocol and genetic background of the rodent models used, it was noted that both genetic background and exposure to silicates [(crystalline) silica and asbestos] are highly relevant to the development of (sub-) clinical systemic autoimmune disease.

CONCLUSION

Parallels were observed between the findings from the animal (this review) and human (epidemiological) studies, arguing that experimental animal models are valuable tools for examining exacerbation or development of autoimmune disease after silicate exposure. However, genetic background and synergism between exposures should be considered in future studies.

[Environment and immunity-Allergies and autoimmune diseases from epidemiological perspective]

Immunity, which denotes the protection of multicellular organisms against various bacterial and viral infections, is an essential protective mechanism for living organisms. Allergy is a reaction to a foreign substance existing in the environment that is basically not a component of the self. Additionally, autoimmune diseases are associated with the dysfunction in the recognition of self and non-self, and are pathological conditions caused by immune cells attacking their own tissues and cells. In this paper, we outline the current status of immunity with respect to the environment from the epidemiological perspective with regard to the following: (1) evolution and immunity, (2) allergy, (3) autoantibodies, (4) autoimmune diseases, (5) relationships of immunity with the environment, allergy, autoantibodies, and autoimmune diseases, and (6) celiac disease.

Mechanisms of Environment-Induced Autoimmunity

Although numerous environmental exposures have been suggested as triggers for preclinical autoimmunity, only a few have been confidently linked to autoimmune diseases. For disease-associated exposures, the lung is a common site where chronic exposure results in cellular toxicity, tissue damage, inflammation, and fibrosis. These features are exacerbated by exposures to particulate material, which hampers clearance and degradation, thus facilitating persistent inflammation. Coincident with exposure and resulting pathological processes is the posttranslational modification of self-antigens, which, in concert with the formation of tertiary lymphoid structures containing abundant B cells, is thought to promote the generation of autoantibodies that in some instances demonstrate major histocompatibility complex restriction. Under appropriate gene-environment interactions, these responses can have diagnostic specificity. Greater insight into the molecular and cellular requirements governing this process, especially those that distinguish preclinical autoimmunity from clinical autoimmunedisease, may facilitate determination of the significance of environmental exposures in human autoimmune disease.

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.

Silica exposure and chronic virus infection synergistically promote lupus-like systemic autoimmunity in mice with low genetic predisposition

Considerable evidence indicates that autoimmune disease expression depends on both genetic and environmental factors. Among potential environmental triggers, occupational airway exposure to crystalline silica and virus infections have been linked to lupus and other autoimmune diseases in both humans and mouse models. Here, we hypothesized that combined silica and virus exposures synergize and induce autoimmune manifestations more effectively than single exposure to either of these factors, particularly in individuals with low genetic predisposition. Accordingly, infection with the model murine pathogen lymphocytic choriomenigitis virus (LCMV) in early life, followed by airway exposure to crystalline silica in adult life, induced lupus-like autoantibodies to several nuclear self-antigens including chromatin, RNP and Sm, concurrent with kidney lesions, in non-autoimmune C57BL/6 (B6) mice. In contrast, given individually, LCMV or silica were largely ineffectual in this strain. These results support a multihit model of autoimmunity, where exposure to different environmental factors acting on distinct immunostimulatory pathways complements limited genetic predisposition and increases the risk of autoimmunity above a critical threshold.

Silicosis and Silica-Induced Autoimmunity in the Diversity Outbred Mouse

Epidemiological studies have confidently linked occupational crystalline silica exposure to autoimmunity, but pathogenic mechanisms and role of genetic predisposition remain poorly defined. Although studies of single inbred strains have yielded insights, understanding the relationships between lung pathology, silica-induced autoimmunity, and genetic predisposition will require examination of a broad spectrum of responses and susceptibilities. We defined the characteristics of silicosis and autoimmunity and their relationships using the genetically heterogeneous diversity outbred (DO) mouse population and determined the suitability of this model for investigating silica-induced autoimmunity. Clinically relevant lung and autoimmune phenotypes were assessed 12 weeks after a transoral dose of 0, 5, or 10 mg crystalline silica in large cohorts of DO mice. Data were further analyzed for correlations, hierarchical clustering, and sex effects. DO mice exhibited a wide range of responses to silica, including mild to severe silicosis and importantly silica-induced systemic autoimmunity. Strikingly, about half of PBS controls were anti-nuclear antibodies (ANA) positive, however, few had disease-associated specificities, whereas most ANAs in silica-exposed mice showed anti-ENA5 reactivity. Correlation and hierarchical clustering showed close association of silicosis, lung biomarkers, and anti-ENA5, while other autoimmune characteristics, such as ANA and glomerulonephritis, clustered separately. Silica-exposed males had more lung inflammation, bronchoalveolar lavage fluid cells, IL-6, and autoantibodies. DO mice are susceptible to both silicosis and silica-induced autoimmunity and show substantial individual variations reflecting their genetic diverseness and the importance of predisposition particularly for autoimmunity. This model provides a new tool for deciphering the relationship between silica exposure, genes, and disease.

Development of autoantibodies precedes clinical manifestations of autoimmune diseases: A comprehensive review

The etiology of autoimmune diseases is due to a combination of genetic predisposition and environmental factors that alter the expression of immune regulatory genes through various mechanisms including epigenetics. Both humoral and cellular elements of the adaptive immune system play a role in the pathogenesis of autoimmune diseases and the presence of autoantibodies have been detected in most but not all autoimmune diseases before the appearance of clinical symptoms. In some cases, the presence or levels of these autoantibodies portends not only the risk of developing a corresponding autoimmune disease, but occasionally the severity as well. This observation is intriguing because it suggests that we can, to some degree, predict who may or may not develop autoimmune diseases. However, the role of autoantibodies in the pathogenesis of autoimmune diseases, whether they actually affect disease progression or are merely an epiphenomenon is still not completely clear in many autoimmune diseases. Because of these gaps in our knowledge, the ability to accurately predict a future autoimmune disease can only be considered a relative risk factor. Importantly, it raises the critical question of defining other events that may drive a patient from a preclinical to a clinical phase of disease.

Environmental Basis of Autoimmunity

The three common themes that underlie the induction and perpetuation of autoimmunity are genetic predisposition, environmental factors, and immune regulation. Environmental factors have gained much attention for their role in triggering autoimmunity, with increasing evidence of their influence as demonstrated by epidemiological studies, laboratory research, and animal studies. Environmental factors known to trigger and perpetuate autoimmunity include infections, gut microbiota, as well as physical and environmental agents. To address these issues, we will review major potential mechanisms that underlie autoimmunity including molecular mimicry, epitope spreading, bystander activation, polyclonal activation of B and T cells, infections, and autoinflammatory activation of innate immunity. The association of the gut microbiota on autoimmunity will be particularly highlighted by their interaction with pharmaceutical agents that may lead to organ-specific autoimmunity. Nonetheless, and we will emphasize this point, the precise mechanism of environmental influence on disease pathogenesis remains elusive.

The global burden of SLE: prevalence, health disparities and socioeconomic impact

Systemic lupus erythematosus (SLE) is a multisystem autoimmune disease that can potentially lead to serious organ complications and even death. Its global burden - in terms of incidence and prevalence, differential impact on populations, economic costs and capacity to compromise health-related quality of life - remains incompletely understood. The reported worldwide incidence and prevalence of SLE vary considerably; this variation is probably attributable to a variety of factors, including ethnic and geographic differences in the populations being studied, the definition of SLE applied, and the methods of case identification. Despite the heterogeneous nature of the disease, distinct patterns of disease presentation, severity and course can often be related to differences in ethnicity, income level, education, health insurance status, level of social support and medication compliance, as well as environmental and occupational factors. Given the potential for the disease to cause such severe and widespread organ damage, not only are the attendant direct costs high, but these costs are sometimes exceeded by indirect costs owing to loss of economic productivity. As an intangible cost, patients with SLE are, not surprisingly, likely to endure considerably reduced health-related quality of life.

Overlap syndrome with Sjögren's syndrome and systemic sclerosis in a steel rolling mill worker: a case report

BACKGROUND

There are few reports about work-related factors associated with Sjögren's syndrome. We report a case of overlap syndrome with Sjögren's syndrome and systemic sclerosis.

CASE PRESENTATION

A 54-year-old man was admitted due to dyspnea on exertion. The results of physical examination and laboratory findings were compatible with Sjögren's syndrome with systemic sclerosis. The patient had no pre-existing autoimmune disease, and denied family history of autoimmune disease. The patient worked in the large-scale rolling department of a steel manufacturing company for 25 years. Hot rolling is a rolling process performed at between 1100 °C and 1200 °C, generating a high temperature and a large amount of fumes, involving jet-spraying of water throughout the process to remove the instantaneously generated oxide film and prevent the high generation of fumes. In this process, workers could be exposed to silica produced by thermal oxidation. Other potential toxic substances including nickel and manganese seemed to be less likely associated with the patient's clinical manifestations.

CONCLUSIONS

Occupational exposure to silica seemed to be associated with the patient's clinical manifestations of overlap syndrome with Sjögren's syndrome and systemic sclerosis. Although the underlying mechanism is still unclear, autoimmune disease including Sjögren's syndrome affects women more often than men and there was no family history of autoimmune disease. These suggested that there was an association between occupational silica exposure and the disease of the patient. Future research about the association between long-term low dose exposure to silica and the development of autoimmune diseases should be encouraged.

Histone H2AX phosphorylation as a measure of DNA double-strand breaks and a marker of environmental stress and disease activity in lupus

Objective

Defective or inefficient DNA double-strand break (DSB) repair results in failure to preserve genomic integrity leading to apoptotic cell death, a hallmark of systemic lupus erythematosus (SLE). Compelling evidence linked environmental factors that increase oxidative stress with SLE risk and the formation of DSBs. In this study, we sought to further explore genotoxic stress sensitivity in SLE by investigating DSB accumulation as a marker linking the effect of environmental stressors and the chromatin microenvironment.

Methods

DSBs were quantified in peripheral blood mononuclear cell subsets from patients with SLE, healthy controls, and patients with rheumatoid arthritis (RA) by measuring phosphorylated H2AX (phospho-H2AX) levels with flow cytometry. Phospho-H2AX levels were assessed in G0/G1, S and G2 cell-cycle phases using propidium iodide staining, and after oxidative stress using 0.5 µM hydrogen peroxide exposure for 0, 2, 5, 10, 30 and 60 min.

Results

DSB levels were significantly increased in CD4+ T cells, CD8+ T cells and monocytes in SLE compared with healthy controls (p=2.16×10⁻⁴, 1.68×10⁻³ and 4.74×10⁻³, respectively) and RA (p=1.05×10⁻³, 1.78×10⁻³ and 2.43×10⁻², respectively). This increase in DSBs in SLE was independent of the cell-cycle phase, and correlated with disease activity. In CD4+ T cells, CD8+ T cells and monocytes, oxidative stress exposure induced significantly higher DSB accumulation in SLE compared with healthy controls (60 min; p=1.64×10⁻⁶, 8.11×10⁻⁷ and 2.04×10⁻³, respectively).

Conclusions

Our data indicate that SLE T cells and monocytes have increased baseline DSB levels and an increased sensitivity to acquiring DSBs in response to oxidative stress. Although the mechanism underlying DSB sensitivity in SLE requires further investigation, accumulation of DSB may serve a biomarker for disease activity in SLE and help explain increased apoptotic cell accumulation in this disease.

Silica, Silicosis, and Autoimmunity

Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response, which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements, suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, and autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However, numerous questions remain unanswered.

Silica Triggers Inflammation and Ectopic Lymphoid Neogenesis in the Lungs in Parallel with Accelerated Onset of Systemic Autoimmunity and Glomerulonephritis in the Lupus-Prone NZBWF1 Mouse

Genetic predisposition and environmental factors influence the development of human autoimmune disease. Occupational exposure to crystalline silica (cSiO₂) has been etiologically linked to increased incidence of autoimmunity, including systemic lupus erythematosus (SLE), but the underlying mechanisms are poorly understood. The purpose of this study was to test the hypothesis that early repeated short-term cSiO₂ exposure will modulate both latency and severity of autoimmunity in the lupus-prone female NZBWF1 mouse. Weekly intranasal exposure to cSiO₂ (0.25 and 1.0 mg) for 4 wk beginning at 9 wk of age both reduced latency and increased intensity of glomerulonephritis. cSiO₂ elicited robust inflammatory responses in the lungs as evidenced by extensive perivascular and peribronchial lymphoplasmacytic infiltration consisting of IgG-producing plasma cells, and CD45R+ and CD3+ lymphocytes that were highly suggestive of ectopic lymphoid tissue (ELT). In addition, there were elevated concentrations of immunoglobulins and the cytokines MCP-1, TNF-α and IL-6 in bronchoalveolar lavage fluid. cSiO₂-associated kidney and lung effects paralleled dose-dependent elevations of autoantibodies and proinflammatory cytokines in plasma. Taken together, cSiO₂-induced pulmonary inflammation and ectopic lymphoid neogenesis in the NZBWF1 mouse corresponded closely to systemic inflammatory and autoimmune responses as well as the early initiation of pathological outcomes in the kidney. These findings suggest that following airway exposure to crystalline silica, in mice genetically prone to SLE, the lung serves as a platform for triggering systemic autoimmunity and glomerulonephritis.

Environmental influences on systemic lupus erythematosus expression

The etiology of systemic lupus erythematosus (SLE) is unknown, but multiple genetic, epigenetic, and environmental risk factors have been implicated. The inheritance of genes alone is not sufficient for developing SLE, suggesting the influence of environmental triggers on disease expression. Despite the tremendous amount of progress in elucidating potential environmental risk factors for SLE, much more needs to be done. An interdisciplinary approach to studies of the causes and, ultimately, prevention of SLE is needed. This article reviews what is understood about the epidemiology of the relationship between environmental exposures and SLE, in addition to emerging areas of study.

Association of systemic lupus erythematosus with uranium exposure in a community living near a uranium-processing plant: a nested case-control study

OBJECTIVE

To explore the hypothesis that cases of systemic lupus erythematosus (SLE) would be found more frequently in community members with high prior uranium exposure in the Fernald Community Cohort (FCC).

METHODS

A nested case-control study was performed using data from the FCC, a volunteer population of individuals who had resided near a uranium ore-processing plant in Fernald, Ohio during the years of plant operation; uranium plant workers were excluded. Members of the FCC were monitored for 18 years. SLE cases were identified using the American College of Rheumatology 1997 revised classification criteria, laboratory testing, and medical record review. Each case was matched to 4 controls by age, race, and sex. Sera from potential cases and controls were screened for autoantibodies. Cumulative exposure to uranium particulates was calculated using a dosimetry model. Logistic regression with covariates was used to calculate the odds ratios (ORs) with 95% confidence intervals (95% CIs) for the probability of an association between uranium exposure and SLE.

RESULTS

The FCC comprised 4,187 individuals with minimal levels of uranium exposure, 1,273 with moderate exposure, and 2,756 with high exposure. The diagnosis of SLE was confirmed in 23 of 31 individuals who had been assigned International Classification of Diseases, Ninth Revision codes for lupus, and was also confirmed in 2 of 43 individuals who had been prescribed hydroxychloroquine. The female to male ratio was 5.25:1. Of the 25 confirmed SLE cases, 12 were in the high exposure group. The presence of SLE was associated with higher levels of uranium exposure (OR 3.92, 95% CI 1.13-13.59; P = 0.031).

CONCLUSION

High uranium exposure is associated with SLE, as compared to matched controls, in this sample of uranium-exposed individuals. Potential explanations for this relationship include possible autoimmune or estrogen effects of uranium, somatic mutation, epigenetic effects, or effects of some other unidentified accompanying exposure.

Expert panel workshop consensus statement on the role of the environment in the development of autoimmune disease

Autoimmune diseases include 80 or more complex disorders characterized by self-reactive, pathologic immune responses in which genetic susceptibility is largely insufficient to determine disease onset. In September 2010, the National Institute of Environmental Health Sciences (NIEHS) organized an expert panel workshop to evaluate the role of environmental factors in autoimmune diseases, and the state of the science regarding relevant mechanisms, animal models, and human studies. The objective of the workshop was to analyze the existing data to identify conclusions that could be drawn regarding environmental exposures and autoimmunity and to identify critical knowledge gaps and areas of uncertainty for future study. This consensus document summarizes key findings from published workshop monographs on areas in which “confident” and “likely” assessments were made, with recommendations for further research. Transcribed notes and slides were reviewed to synthesize an overview on exposure assessment and questions addressed by interdisciplinary panels. Critical advances in the field of autoimmune disease research have been made in the past decade. Collaborative translational and interdisciplinary research is needed to elucidate the role of environmental factors in autoimmune diseases. A focus on exposure assessment methodology is needed to improve the effectiveness of human studies, and more experimental studies are needed to focus on causal mechanisms underlying observed associations of environmental factors with autoimmune disease in humans.

Relationship of environmental exposures and ankylosing spondylitis and spinal mobility: US NHAENS, 2009-2010

It was aimed to study the relationships of different sets of urinary environmental chemical concentrations and ankylosing spondylitis in a national and population-based setting. Data were extracted from United States National Health and Nutrition Examination Surveys, 2009-2010. Information on demographics was obtained by household interview and ankylosing spondylitis clinical measures and urines were taken at examination. People with abnormal occiput-to-wall distance were found to have higher urinary cadmium (OR 2.17, 95 % CI 1.34-3.52, p = 0.004), antimony (OR 1.74, 95 % CI 1.15-2.62, p = 0.012), tungsten (OR 1.91, 95 % CI 1.39-2.64, p = 0.001), uranium (OR 1.49, 95 % CI 1.03-2.15, p = 0.036), and trimethylarsine oxide (OR 5.01, 95 % CI 2.34-10.71, p < 0.001) concentrations. Moreover, people who resided in older households tended to have abnormal ankylosing spondylitis clinical measures, compared to those who resided in households that were built in 1990 or after. The odds were 1.74 for households built in 1978-1989 and 1.81 for those built in 1940 or earlier.

Requirements for innate immune pathways in environmentally induced autoimmunity

There is substantial evidence that environmental triggers in combination with genetic and stochastic factors play an important role in spontaneous autoimmune disease. Although the specific environmental agents and how they promote autoimmunity remain largely unknown, in part because of diverse etiologies, environmentally induced autoimmune models can provide insights into potential mechanisms. Studies of idiopathic and environmentally induced systemic autoimmunity show that they are mediated by common adaptive immune response genes. By contrast, although the innate immune system is indispensable for autoimmunity, there are clear differences in the molecular and cellular innate components that mediate specific systemic autoimmune diseases, suggesting distinct autoimmune-promoting pathways. Some of these differences may be related to the bifurcation of toll-like receptor signaling that distinguishes interferon regulatory factor 7-mediated type I interferon production from nuclear factor-κB-driven proinflammatory cytokine expression. Accordingly, idiopathic and pristane-induced systemic autoimmunity require both type I interferon and proinflammatory cytokines whereas the less aggressive mercury-induced autoimmunity, although dependent on nucleic acid-binding toll-like receptors, does not require type I interferon but needs proinflammatory cytokines. Scavenger receptors and the inflammasome may contribute to silica-induced autoimmunity. Greater understanding of the innate mechanisms responsible for idiopathic and environmentally induced autoimmunity should yield new information into the processes that instigate and drive systemic autoimmunity.

Epidemiology of environmental exposures and human autoimmune diseases: findings from a National Institute of Environmental Health Sciences Expert Panel Workshop

Autoimmune diseases (AID) are a collection of many complex disorders of unknown etiology resulting in immune responses to self-antigens and are thought to result from interactions between genetic and environmental factors. Here we review the epidemiologic evidence for the role of environmental factors in the development of human AID, the conclusions that can be drawn from the existing data, critical knowledge gaps, and research needed to fill these gaps and to resolve uncertainties. We specifically summarize the state of knowledge and our levels of confidence in the role of specific agents in the development of autoimmune diseases, and we define the areas of greatest impact for future investigations. Among our consensus findings we are confident that: 1) crystalline silica exposure can contribute to the development of several AID; 2) solvent exposure can contribute to the development of systemic sclerosis; 3) smoking can contribute to the development of seropositive rheumatoid arthritis; and 4) an inverse association exists between ultraviolet radiation exposure and the risk of development of multiple sclerosis. We suggest that more studies of phenotypes, genotypes, and multiple exposures are needed. Additional knowledge gaps needing investigation include: defining important windows in the timing of exposures and latencies relating to age, developmental state, and hormonal changes; understanding dose-response relationships; and elucidating mechanisms for disease development. Addressing these essential issues will require more resources to support research, particularly of rare AID, but knowledge of the risks conferred by environmental factors in specific genetic contexts could pave the way for prevention of AID in the future.

Gender differences in autoimmunity associated with exposure to environmental factors

Autoimmunity is thought to result from a combination of genetics, environmental triggers, and stochastic events. Gender is also a significant risk factor with many diseases exhibiting a female bias. Although the role of environmental triggers, especially medications, in eliciting autoimmunity is well established less is known about the interplay between gender, the environment and autoimmunity. This review examines the contribution of gender in autoimmunity induced by selected chemical, physical and biological agents in humans and animal models. Epidemiological studies reveal that environmental factors can be associated with a gender bias in human autoimmunity. However many studies show that the increased risk of autoimmunity is often influenced by occupational exposure or other gender biased activities. Animal studies, although often prejudiced by the exclusive use of female animals, reveal that gender bias can be strain specific suggesting an interaction between sex chromosome complement and background genes. This observation has important implications because it argues that within a gender biased disease there may be individuals in which gender does not contribute to autoimmunity. Exposure to environmental factors, which encompasses everything around us, adds an additional layer of complexity. Understanding how the environment influences the relationship between sex chromosome complement and innate and adaptive immune responses will be essential in determining the role of gender in environmentally-induced autoimmunity.

Air pollution in autoimmune rheumatic diseases: a review

Air pollution consists of a heterogeneous mixture of gasses and particles that include carbon monoxide, nitrates, sulfur dioxide, ozone, lead, toxic by-product of tobacco smoke and particulate matter. Oxidative stress and inflammation induced by inhaled pollutants may result in acute and chronic disorders in the respiratory system, as well as contribute to a state of systemic inflammation and autoimmunity. This paper reviews the mechanisms of air contaminants influencing the immune response and autoimmunity, and it focuses on studies of inhaled pollutants triggering and/or exacerbating rheumatic diseases in cities around the world. Remarkably, environmental factors contribute to the onset of autoimmune diseases, especially smoking and occupational exposure to silica in rheumatoid arthritis and systemic lupus erythematosus. Other diseases such as scleroderma may be triggered by the inhalation of chemical solvents, herbicides and silica. Likewise, primary vasculitis associated with anti-neutrophil cytoplasmic antibody (ANCA) may be triggered by silica exposure. Only few studies showed that air pollutants could trigger or exacerbate juvenile idiopathic arthritis and systemic lupus erythematosus. In contrast, no studies of tropospheric pollution triggering inflammatory myopathies and spondyloarthropathies were carried out. In conclusion, air pollution is one of the environmental factors involved in systemic inflammation and autoimmunity. Further studies are needed in order to evaluate air pollutants and their potentially serious effects on autoimmune rheumatic diseases and the mechanisms involved in the onset and the exacerbation of these diseases.

Prevalence of connective tissue disease in silicosis (1985-2006)-a report from the state of Michigan surveillance system for silicosis

BACKGROUND

The risk of developing clinical connective tissue disease (CTD) has been reported to be increased among individuals with silica exposure.

METHODS

We reviewed the medical records of individuals reported to the Michigan Silicosis Surveillance system from 1985 to 2006 to confirm the diagnosis of silicosis and determine the presence of CTDs.

RESULTS

From 1985 to 2006, 1,022 cases were confirmed to have silicosis. Medical records of 790 cases were available. Thirty-three individuals had rheumatoid arthritis (RA) [prevalence 4.2% (prevalence ratio (RR) ranged from 2.26, 95% CI: 1.57-3.25 to 6.96, 95% CI: 2.93-16.53) depending on the reference rate used], two had scleroderma [prevalence 0.3% (RR 28.3, 95% CI: 6.09-129.98)], one had systemic lupus erythematosus [prevalence 0.1% (RR 2.53, 95% CI: 0.30-21.64)], two had Sjogrens syndrome [prevalence 0.3% (RR 0.42, 95% CI: 0.09-2.08)], and six had anti-neutrophil cytoplasm antibody (ANCA) vasculitis [prevalence 0.8% (RR 25.3, 95% CI: 6.34-101.04)]. There was no difference between those with and without CTD with respect to age, race, industry type, history of tuberculosis, application for workers' compensation, or severity of fibrotic changes on chest X-ray.

CONCLUSIONS

A two- to eightfold risk for RA and systemic lupus erythematosus, with a greater than 24-fold risk for scleroderma and ANCA vasculitis was found in individuals with silicosis. The most common CTD among silicotics in the Michigan disease registry was RA. Though not classically included in the category of CTD, ANCA-associated vasculitis was found to have a much greater prevalence amongst silicosis patients than the general population.

Autoimmune diseases and autoantibodies in the first degree relatives of patients with systemic sclerosis

OBJECTIVE

To determine aggregation of autoimmune diseases in the first degree relatives (FDR) of patients with systemic sclerosis (SSc) and to investigate frequencies of antinuclear antibodies (ANA) and other autoantibodies in the FDRs and spouses of patients with SSc.

METHODS

Information on FDRs including history of autoimmune disease was obtained from unrelated SSc probands in the Scleroderma Family Registry and DNA Repository. FDRs were contacted to verify any reported autoimmune diseases. The prevalence of autoimmune disease in probands' families was compared with the corresponding prevalence in controls' families as reported in the literature. Furthermore, sera from probands' FDRs and spouses in addition to unrelated controls were investigated for the presence of autoantibodies (ANA).

RESULTS

We investigated 4612 FDRs of 1071 SSc probands. SSc probands with anti-centromere antibodies (ACA) and limited disease type were more likely to report familial autoimmunity (p=0.022 and p=0.041, respectively). The four most prevalent autoimmune diseases among SSc probands' FDRs were hypothyroidism (4%), Rheumatoid arthritis (1.5%), hyperthyroidism (1.3%) and systemic lupus erythematosus-SLE (0.4%). Compared to control families, SLE, hypothyroidism and hyperthyroidism were more common in SSc probands' families. The most striking increase for familial prevalence was observed in SLE (OR=16.98, 95% CI=1.02-227.82, p=0.004). ANA was present in 14.2% of probands' FDR's and 8.6% of spouses and did not differ from the prevalence of ANA among controls (p=0.124 and p=0.477, respectively). Only two FDRs of probands had ACA while none had anti-topoisomerase antibodies.

CONCLUSION

Our study implies varying degrees of risk for familial autoimmunity among subtypes of SSc and provides further support for common genetic and potentially environmental factors leading to SSc and SLE.

Silica exposure, smoking, silicosis and lung cancer--complex interactions

BACKGROUND

Establishing a clear relationship between workplace exposures and cancer is often difficult. The latent period for cancer development can make it difficult to establish a definite cause-effect relationship. The picture is further complicated by variable job histories, concomitant exposure to other carcinogens and other factors such as genetic susceptibility and poor nutrition. The lack of accurate and detailed record keeping may potentially mask informative differences among group of workers. Removing or reducing exposures to probable and known carcinogens, however, can prevent workplace cancer.

AIM

This paper gives an overview of the literature reporting investigations of the relationship between exposure to silica and development of lung cancer with a focus on the controversy concerning the roles of silicosis and smoking in the development of cancer.

METHOD

A literature search was conducted to identify epidemiologic papers on silica, silicosis and lung cancer using electronic databases (MEDLINE, PubMed, Web of Science) from 1996 onwards and paper bibliographies.

RESULTS

If silicosis were the necessary step leading to lung cancer, enforcing the current silica standards would protect workers against lung cancer risk as well. Alternatively, a direct silica-lung cancer association that has been suggested implies that regulatory standards should be revised accordingly.

CONCLUSION

Further research is needed in order to understand the complex pattern of interactions leading to lung cancer among silica-exposed workers (and cancers and workplace exposures in general) and to understand whether and to what extent other workplace lung carcinogens, total respirable dust and total surface size and age of silica particles affect the carcinogenic potential of silica. In addition, the apparent paradox of a lower lung cancer risk in some workplaces with high-level silica exposure needs further investigation.

Occupational exposures and risk of systemic lupus erythematosus

This review summarizes the growing body of epidemiologic and experimental research pertaining to the relationship between SLE and occupational exposures, such as crystalline silica, solvents, and pesticides. Epidemiologic studies, using different designs in different settings, have demonstrated moderate to strong associations between occupational silica exposure and SLE. Recent experimental studies of silica in lupus-prone mice provide support for the idea that, in addition to its known adjuvant effect, silica exposure increases the generation of apoptotic material, an important source of self-antigen. Despite compelling experimental studies of the organic solvent trichloroethylene (TCE) in lupus-prone mice, there is little evidence of an overall association of SLE and occupational exposure to a broad classification of solvents in humans. However, there is a lack of data on SLE in occupational cohorts with exposures to TCE or other specific solvents. One epidemiologic study reported an association of pesticide mixing and SLE, while a recent experimental study reported accelerated disease in pesticide-treated lupus-prone mice. Other occupational exposures worth investigating include asbestos, metals, and UV radiation. Attention should also be given to the role of gene-environment interactions, which may require large, multi-site studies that collect both genetic material and occupational exposure data. The quality of exposure assessment is an important consideration in designing and evaluating these studies. The use of pre-clinical endpoints (e.g. high-titer autoantibodies) in occupational cohorts with well-characterized exposure histories may reveal occupational risk factors for autoimmunity, and may also provide baseline data for studies of determinants of progression to SLE.

A role for Fli-1 in B cell proliferation: implications for SLE pathogenesis

Transgenic overexpression of Fli-1 in normal mice leads to SLE-like disease and increased expression was reported in SLE-affected human and murine lymphocytes. Reducing Fli-1 expression in MRL/lpr mice decreased antibody production, proteinuria, renal pathology, and mortality. Compared to those with wild-type expression of Fli-1, we report here that proliferative responses of Fli-1-deficient naïve B cells to several mitogens were reduced in lupus-prone and control mice. Expression of mitogen receptors, including BCR, TLR4, and TLR9, was not significantly impacted in Fli-1-deficient naïve B cells. IL12a transcripts were upregulated and NFAT transcripts were downregulated in Fli-1-deficient MRL/lpr B cells. These results demonstrate that Fli-1 deficiency affects B cell proliferative responses to mitogens, independent of BCR and TLR expression. IL12a and NFAT, known to influence proliferation, were identified as potential mediators of this effect. This may be a mechanism by which overexpression of Fli-1 contributes to B cell hyperactivity and subsequent SLE pathogenesis.

State-of-the-science review of the occupational health hazards of crystalline silica in abrasive blasting operations and related requirements for respiratory protection

Excessive exposures to airborne crystalline silica have been known for over 100 years to pose a serious health hazard. Work practices and regulatory standards advanced as the knowledge of the hazards of crystalline silica evolved. This article presents a comprehensive historical examination of the literature on exposure, health effects, and personal protective equipment related to silica and abrasive blasting operations over the last century. In the early 1900s, increased death rates and prevalence of pulmonary disease were observed in industries that involved dusty operations. Studies of these occupational cohorts served as the basis for the first occupational exposure limits in the 1930s. Early exposure studies in foundries revealed that abrasive blasting operations were particularly hazardous and provided the basis for many of the engineering control and respiratory protection requirements that are still in place today. Studies involving abrasive blasters over the years revealed that engineering controls were often not completely effective at reducing airborne silica concentrations to a safe level; consequently, respiratory protection has always been an important component of protecting workers. During the last 15-20 yr, quantitative exposure-response modeling, experimental animal studies, and in vitro methods were used to better understand the relationship between exposure to silica and disease in the workplace. In light of Occupational Safety and Health Administration efforts to reexamine the protectiveness of the current permissible exposure limit (PEL) for crystalline silica and its focus on protecting workers who are known to still be exposed to silica in the workplace (including abrasive blasters), this state-of-the-science review of one of the most hazardous operations involving crystalline silica should provide useful background to employers, researchers, and regulators interested in the historical evolution of the recognized occupational health hazards of crystalline silica and abrasive blasting operations and the related requirements for respiratory protection.

Occupational exposures and risk of systemic lupus erythematosus: a review of the evidence and exposure assessment methods in population- and clinic-based studies

Epidemiologic and experimental research suggests a potential role of occupational exposures in the development of systemic lupus erythematosus (SLE). A plausible association has been identified in studies of occupational silica exposure and SLE, complemented by experimental studies in lupus-prone mice exploring potential mechanisms related to apoptosis and immune dysregulation. Experimental studies of the solvent trichloroethylene in lupus-prone mice provide evidence of effects on immune function, including increased production of autoantibodies and activation of CD4+ T cells. However, few studies of occupational solvent exposure and SLE have been conducted, and those that are available show little evidence of an association. There is some suggestion from the available studies of the potential influence of pesticides on SLE, but as with solvents, the specific type of pesticides that may be implicated is not known. Our understanding of the role of occupational exposures in SLE could be advanced by the development of larger, multisite or parallel studies that utilize similar questionnaire and exposure evaluation methods. Multiple studies using comparable exposure measures are needed to provide sufficient sample size for examining gene-environment interactions. We provide a general overview of data requirements and methods available for the assessment and evaluation of occupational exposures in clinical and population-based studies of SLE.

Silica-associated systemic lupus erythematosus in an elderly man

The predominantly young woman-orientated systemic lupus erythematosus (SLE) is a disease that involves an extremely complicated and multifactorial interaction of various genetic and environmental factors. Crystalline silica (Si) may act as an immunoadjuvant to increase secretions of inflammatory endogenous substances and antibody production. In addition, previous studies have suggested that exposure to Si may induce SLE. Although the biologic mechanism of Si in SLE is unclear, defective apoptosis leading to the prolonged survival of pathogenic lymphocytes was thought to be one of mechanisms of Si-associated SLE (sSLE). In the present study, a rare case of an elderly man suffering from sSLE responded well to glucocorticoid therapy. The present findings were reviewed with reference to previous literature.

Environment and systemic lupus erythematosus: an overview

Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology that manifests as a pleomorphic systemic disease mainly affecting females. The variety of autoantibodies found in the serum of patients indicate that SLE is an autoimmune disease, but the mechanisms leading to the aberrant responses are not clearly understood although it is thought that a number of genetic and environmental factors may be involved. Environmental (or non-genetic) exposures could include infectious agents, chemicals or other compounds capable of modulating immune responses such as occupational/environmental pollutants or drugs, and behavioural factors such as smoking and diet. Environmental exposures may lead to the production of autoreactive T cells and autoantibodies, the stimulation of pro- and antiinflammatory cytokines, and target end-organ damage, but are not so convincing as agents causing SLE. Exposure to viruses increases antibody titres, but these may be the result of polyclonal B cell activation. The amount and timing of exposure to different environmental factors may play a significant and complex role in the pathogenesis of SLE and other autoimmune diseases. A better understanding of the etiopathogenetic mechanism of SLE is required in order to clarify the multiple interactions between environmental exposures and genetic factors.

Occupational silica and solvent exposures and risk of systemic lupus erythematosus in urban women

OBJECTIVE

To assess the risk of systemic lupus erythematosus (SLE) associated with occupational exposure to silica dust and organic solvents in an urban population.

METHODS

Women with SLE were identified through both community screening and hospital databases in 4 predominantly African American neighborhoods in Boston. Female control patients were volunteers from the same communities and were screened for the absence of connective tissue disease. Demographic factors, smoking history, and a detailed occupational history, including exposures to specific chemicals, were obtained by in-person interviews. The exposure assessment was based on independent evaluation of the occupational history by 2 reviewers who were blinded to each subject's disease status. The risks associated with exposure to silica and solvents were analyzed using multivariate conditional logistic regression models, adjusted for potential confounders.

RESULTS

Ninety-five patients and 191 age- and race-matched controls were included in this analysis. Exposure to silica for longer than 1 year was associated with SLE (odds ratio [OR] 4.3, 95% confidence interval [95% CI] 1.7-11.2). An exposure-response effect was seen for longer duration of exposures to silica (P for trend = 0.01). The association between occupational exposure to organic solvents and SLE was not statistically significant (OR 1.04, 95% CI 0.34-3.2).

CONCLUSION

Silica exposure from a variety of industrial occupations in urban areas is associated with an increased risk of SLE. A longer duration of exposure to silica dust is associated with greater risks. This study provides further impetus for additional research into the influence of modifiable exposures on the pathogenesis of SLE.

Occupational and environmental exposures as risk factors for systemic lupus erythematosus

Although genetic susceptibility plays a strong role in the etiology of systemic lupus erythematosus (SLE), recent research has provided new evidence of the potential influence of environmental factors in the risk for this disease. This paper describes epidemiologic and experimental research pertaining to occupational and environmental sources of exposure to respirable crystalline silica, solvents and pesticides, and two "lifestyle" factors (smoking and hair dye use). As has been seen with other systemic autoimmune diseases (eg, systemic sclerosis and rheumatoid arthritis), a series of epidemiologic studies, using different designs in different settings, have demonstrated relatively strong and consistent associations between occupational silica exposure and SLE. The type and quality of exposure assessment is an important consideration in evaluating these studies. Recent experimental studies examined the effect of trichloroethylene exposure in MRL+/+ mice, but to date there have been few epidemiologic studies of solvents and SLE. There are numerous avenues with respect to environmental factors in SLE that need additional research.

Comparing Questionnaire-Based Methods to Assess Occupational Silica Exposure

BACKGROUND

Epidemiologic assessment of occupational exposure to silica is typically limited to long-term work in the dusty trades, primarily in jobs held by men. We compared alternative questionnaire-based methods to assess silica exposure in a recent case-control study of 265 patients with systemic lupus erythematosus (mostly women) and 355 controls randomly selected from state driver's license registries and frequency-matched by age and sex.

METHODS

In-person interviews included a job history (all jobs held at least 12 months) and checklist of silica-related jobs and tasks (work of at least 2 weeks). Three industrial hygienists reviewed job descriptions without knowing case-control status. Potential high- or moderate-intensity exposures were confirmed or revised based on follow-up telephone interviews.

RESULTS

In the full assessment including all work of at least 2 weeks, 9% of cases and 4% of controls were classified as medium or high silica exposure (odds ratio of disease = 2.9; 95% confidence interval = 1.3-6.4). In contrast, only 4% of cases and 9% of controls were identified by the standardized code groups index as having worked in silica-related industries or occupations for at least 12 months, providing a much lower risk estimate for disease (0.4; 0.2-0.9).

CONCLUSIONS

Specific task-based questions must be included to assess the full potential of occupational silica exposure. These findings highlight the limitations of using standardized code groups to define exposure or to select jobs for industrial hygienist review.

Lupus erythematosus induced by medications, ultraviolet radiation, and other exogenous agents: A review, with special focus on the development of subacute cutaneous lupus erythematosus in a genetically predisposed individual

Exogenous agents implicated in or suspected of precipitating subacute cutaneous lupus erythematosus (SCLE) and lupus erythematosus (LE) are reviewed. An illustrative case of environmentally induced SCLE is presented. A previously healthy 30-year male homozygous for the tumor necrosis factor-alpha (TNF-alpha) 308. A promoter allele developed SCLE after spending several hours removing fertilizer- and pesticide-containing hay from an agricultural barn in the springtime. The cutaneous eruption soon resolved, only to reappear 3 weeks later on the day the patient re-entered the barn. An environmental agent present in the barn, coupled with springtime ultraviolet light, likely triggered the disease in this immunogenetically susceptible individual.

Occupational silica exposure and risk of various diseases: an analysis using death certificates from 27 states of the United States

BACKGROUND

Although crystalline silica exposure is associated with silicosis, lung cancer, pulmonary tuberculosis, and chronic obstructive pulmonary disease (COPD), there is less support for an association with autoimmune disease, and renal disease.

METHODS

Using data from the US National Occupational Mortality Surveillance (NOMS) system, a matched case-control design was employed to examine each of several diseases (including silicosis, lung cancer, stomach cancer, oesophageal cancer, COPD, pulmonary tuberculosis, sarcoidosis, systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, and various types of renal disease). Cases were subjects whose death certificate mentioned the disease of interest. A separate control group for each of the diseases of interest was selected from among subjects whose death certificate did not mention the disease of interest or any of several diseases reported to be associated with crystalline silica exposure. Subjects were assigned into a qualitative crystalline silica exposure category based on the industry/occupation pairing found on their death certificate. We also investigated whether silicotics had a higher risk of disease compared to those without silicosis.

RESULTS

Those postulated to have had detectable crystalline silica exposure had a significantly increased risk for silicosis, COPD, pulmonary tuberculosis, and rheumatoid arthritis. In addition, a significant trend of increasing risk with increasing silica exposure was observed for these same conditions and for lung cancer. Those postulated to have had the greatest crystalline silica exposure had a significantly increased risk for silicosis, lung cancer, COPD, and pulmonary tuberculosis only. Finally, those with silicosis had a significantly increased risk for COPD, pulmonary tuberculosis, and rheumatoid arthritis.

CONCLUSIONS

This study corroborates the association between crystalline silica exposure and silicosis, lung cancer, COPD, and pulmonary tuberculosis. In addition, support is provided for an association between crystalline silica exposure and rheumatoid arthritis.

Environmental chemicals and autoimmune disease: cause and effect

Many important clues have been provided by the relationship of certain medications to lupus and other autoimmune syndromes. These are temporary conditions that resolve when the medication is removed. There are now over 70 such medications which have been reported related to these autoimmune conditions. Interest continues to grow in the potential for environmental substances to cause these syndromes. Among those under suspicion are hydrazines, tartrazines, hair dyes, trichloroethylene, industrial emissions and hazardous wastes. Other possible associations include silica, mercury, cadmium, gold and L canavanine. Two recognised outbreaks include 'toxic oil syndrome' related to contaminated rape seed oil in Spain in 1981 and exposure to a contaminated environmental substance associated with an autoimmune attack on muscle tissue in 1989. Recently, there have been proposals made for the definition and identification of environmentally associated immune disorders. The World Health Organisation (WHO) has also provided recent publications for other environmentally related problems. All these aspects will be presented and reviewed in detail.

Occupational exposure to crystalline silica and risk of systemic lupus erythematosus: a population-based, case-control study in the southeastern United States

OBJECTIVE

Crystalline silica may act as an immune adjuvant to increase inflammation and antibody production, and findings of occupational cohort studies suggest that silica exposure may be a risk factor for systemic lupus erythematosus (SLE). We undertook this population-based study to examine the association between occupational silica exposure and SLE in the southeastern US.

METHODS

SLE patients (n = 265; diagnosed between January 1, 1995 and July 31, 1999) were recruited from 4 university rheumatology practices and 30 community-based rheumatologists in 60 contiguous counties. Controls (n = 355), frequency-matched to patients by age, sex, and state of residence, were randomly selected from driver's license registries. The mean age of the patients at diagnosis was 39 years; 91% were women and 60% were African American. Detailed occupational and farming histories were collected by in-person interviews. Silica exposure was determined through blinded assessment of job histories by 3 industrial hygienists, and potential medium- or high-level exposures were confirmed through followup telephone interviews. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression.

RESULTS

More patients (19%) than controls (8%) had a history of medium- or high-level silica exposure from farming or trades. We observed an association between silica and SLE (medium exposure OR 2.1 [95% CI 1.1-4.0], high exposure OR 4.6 [95% CI 1.4-15.4]) that was seen in separate analyses by sex, race, and at different levels of education.

CONCLUSION

These results suggest that crystalline silica exposure may promote the development of SLE in some individuals. Additional research is recommended in other populations, using study designs that minimize potential selection bias and maximize the quality of exposure assessment.

Occupational exposures and autoimmune diseases

Autoimmune diseases are pathologic conditions defined by abnormal autoimmune responses and characterized by immune system reactivity in the form of autoantibodies and T cell responses to self-structures. Here we review the limited but growing epidemiologic and experimental literature pertaining to the association between autoimmune diseases and occupational exposure to silica, solvents, pesticides, and ultraviolet radiation. The strongest associations (i.e., relative risks of 3.0 and higher) have been documented in investigations of silica dust and rheumatoid arthritis, lupus, scleroderma and glomerulonephritis. Weaker associations are seen, however, for solvent exposures (in scleroderma, undifferentiated connective tissue disease, and multiple sclerosis) and for farming or pesticide exposures (in rheumatoid arthritis). Experimental studies suggest two different effects of these exposures: an enhanced proinflammatory (TH1) response (e.g., TNF-alpha and IL-1 cytokine production with T cell activation), and increased apoptosis of lymphocytes leading to exposure to or modification of endogenous proteins and subsequent autoantibody formation. The former is a general mechanism that may be relevant across a spectrum of autoimmune diseases, whereas the latter may be a mechanism more specific to particular diseases (e.g., ultraviolet radiation, Ro autoantibodies, and lupus). Occupational exposures are important risk factors for some autoimmune diseases, but improved exposure assessment methods and better coordination between experimental/animal models and epidemiologic studies are needed to define these risks more precisely.

Pulmonary silicosis and systemic lupus erythematosus in men: a report of two cases

We reporttwo cases of coexistence of pulmonary silicosis and systemic lupus erythematosus (SLE). The patients are two men with SLE exposed to silica for 20 years. The hypothesis that silica exposure is linked to a wide variety of known or suspected autoimmune diseases, including SLE, has been discussed in the last decade but few cases of pulmonary silicosis and SLE were reported. Our purpose was to bring attention to the increasing evidence that silica may also cause or stimulate SLE, and to suggest that the researchers look for occupational exposure, mainly in male SLE patients.

Antimalarials

Antimalarial medications have become the parenteral drugs of choice for treating the cutaneous manifestations of lupus erythematosus. The immune-modulating activity of these agents makes them useful in a variety of other dermatoses. With prudent dosage and monitoring, these agents can be used safely and effectively in the treatment and management of dermatologic disease.