Silica exposure and altered regulation of autoimmunity

A toxicological profile of silica nanoparticles

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

Antibrush Border Antibody Disease: A Case Report and Literature Review

Anti-brush border antibody (ABBA) disease, also called anti-low-density lipoprotein receptor-related protein 2 (anti-LRP2) nephropathy, occurs due to the formation of antibodies against brush border antigens of the renal proximal convoluted tubule. We report a case of ABBA disease in a male farmer in his 30s who presented with 2 years of polyuria, dysuria, nocturia, and urinary urgency. He described a history of long-term occupational exposure to pesticides and silica, evolving into possible pneumoconiosis, and prior pulmonary tuberculosis. At presentation, he had reduced kidney function (serum creatinine 3.6 mg/dL) with hyponatremia, hypokalemia, hypophosphatemia, a normal anion gap, metabolic acidosis, and respiratory acidosis, and 2.2 g/day of urine proteinuria. The kidney biopsy was consistent with ABBA, showing amorphous immune-deposits in the tubular basement membrane and strong positivity on indirect immunofluorescence in the brush border of the proximal tubules. The trigger for production of ABBA is still unknown, but it may be associated with chronic conditions such as pulmonary tuberculosis and occupational exposures such as silica and pesticides, as seen in the patient in this report. Most cases do not respond to immunosuppression, and the prognosis is poor.

Regulation of crystal induced inflammation: current understandings and clinical implications

Introduction: Accumulation of abnormal crystals in the body, derived from endogenous or exogenous materials can drive a wide spectrum of inflammatory disease states. It is well established that intra-articular deposition of monosodium urate (MSU) and calcium pyrophoshate (CPP) crystals contributes to joint destruction through pro-inflammatory processes.Areas covered: This review will focus on current understanding and recent novelty about the mechanisms and the clinical implications of the inflammation induced by MSU and CPP crystals.Expert opinion: Advances in molecular biology reveal that at the base of the inflammatory cascade, stimulated by MSU or CPP crystals, there are many complex cellular mechanisms mainly involving the NLRP3 inflammasome, the hallmark of autoinflammatory syndromes. The extensive studies carried out through in vitro and in vivo models along with a better clinical definition of the disease has led to an optimized use of existing drugs and the introduction of novel therapeutic strategies. In particular, the identification of IL-1 as the most important target in gout and pseudogout has made it possible to expand the pharmacological indications of anti-IL-1 biological drugs, opening new therapeutic perspectives for patients.

Occupational Exposures and Smoking in Eosinophilic Granulomatosis With Polyangiitis: A Case-Control Study

OBJECTIVE

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Environmental agents and occupational exposures may confer susceptibility to EGPA, but data are scarce. This study was undertaken to investigate the association between occupational exposures (e.g., silica, farming, asbestos, and organic solvents) and other environmental agents (e.g., smoking) and the risk of EGPA.

METHODS

Patients with newly diagnosed EGPA (n = 111) and general population controls (n = 333) who were matched for age, sex, and geographic area of origin were recruited at a national referral center for EGPA. Exposures were assessed using a dedicated questionnaire administered by a specialist in occupational medicine, under blinded conditions. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Exposures to silica (OR 2.79 [95% CI 1.55-5.01], P = 0.001), organic solvents (OR 3.19 [95% CI 1.91-5.34], P < 0.001), and farming (OR 2.71 [95% CI 1.71-4.29], P < 0.001) were associated with an increased risk of EGPA. Co-exposure to silica and farming yielded an OR of 9.12 (95% CI 3.06-27.19, P < 0.001), suggesting a multiplicative effect between these 2 exposures. Smoking (current and former smokers combined) was significantly less frequent among patients with EGPA compared to controls (OR 0.49 [95% CI 0.29-0.70], P < 0.001). The pack-year index was also lower among patients with EGPA (OR 0.96 [95% CI 0.94-0.98], P < 0.001). The association of silica and farming was primarily aligned with ANCA-positive EGPA, while the association of smoking status and organic solvents was primarily aligned with ANCA-negative EGPA.

CONCLUSION

The environment can influence susceptibility to EGPA. Exposure to silica, farming, or organic solvents is associated with an increased risk of EGPA, while smoking is associated with a lower risk. These exposures seem to have distinct effects on different EGPA subsets.

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

OBJECTIVE

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSION

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

The Effects of Asbestos Fibers on Human T Cells

Asbestos exposure causes malignant tumors such as lung cancer and malignant mesothelioma. The effects of asbestos fibers on immunocompetent cells, however, have not been well studied. Asbestos physically comprises a fibrous substance, which differs from silica particles which are a particulate substance, although chemically it is a mineral silicate. Since silicosis patients previously exposed to silica particles often suffer from lung and autoimmune diseases, it is clear that silica exposure impairs immune tolerance. Similarly, asbestos may alter the immune system in asbestos-exposed individuals. Given that malignant tumors can result following exposure to asbestos, the attenuation of anti-tumor immunity in cases of asbestos exposure is an important area of investigation. We observed the effect of asbestos fibers on T lymphocytes, such as CD8+ cytotoxic T lymphocytes (CTLs), CD4+ helper T (Th), and regulatory T (Treg) cells, and showed that anti-tumor immunity was attenuated, as demonstrated in a system that stimulates fresh cells isolated from peripheral blood in vitro and a system that is continuously exposed to a cell line. In this manuscript, we introduce the experiments and results of studies on CTLs, as well as Th and Treg cells, and discuss how future changes in immunocompetent cells induced by asbestos fibers can be clinically linked.

Transcriptome profile analysis reveals a silica-induced immune response and fibrosis in a silicosis rat model

Silicosis is a type of pneumoconiosis caused by the inhalation of silica dust. It is characterized by inflammation and fibrosis of the lung. Although many studies have reported that crystalline silica-inhalation into the lung initiates the immune response, activating effector cells and triggering the inflammatory cascade with subsequent elaboration of the extracellular matrix and fibrosis, the mechanism of silicosis pathogenesis remains unclear. In the present study, we established a silica inhalation-induced silicosis rat model validated by histological and cytokine analyses. RNA-seq and bioinformatic analyses showed that 600 genes were upregulated and 537 genes were downregulated in the silica-treated group. GO enrichment analysis indicates that these differentially expressed genes are enriched in several biological processes including immune response and organism remodeling. KEGG enrichment analysis showed that 53 enriched pathways were mainly associated with human diseases, immune response, signal transduction, and fibrosis process. Since alternative splicing of pre-mRNAs is also essential for the regulation of gene expression, we identified several alternative pre-mRNA splicing events in the fibrotic process. This study will provide a foundation to understand the molecular mechanism of the pulmonary fibrosis caused by silica.

Imaging flow cytometry methods for quantitative analysis of label-free crystalline silica particle interactions with immune cells

Exposure to respirable fractions of crystalline silica quartz dust particles is associated with silicosis, cancer and the development of autoimmune conditions. Early cellular interactions are not well understood, partly due to a lack of suitable technological methods. Improved techniques are needed to better quantify and study high-level respirable crystalline silica exposure in human populations. Techniques that can be applied to complex biological matrices are pivotal to understanding particle-cell interactions and the impact of particles within real, biologically complex environments. In this study, we investigated whether imaging flow cytometry could be used to assess the interactions between cells and crystalline silica when present within complex biological matrices. Using the respirable-size fine quartz crystalline silica dust Min-u-sil® 5, we first validated previous reports that, whilst associating with cells, crystalline silica particles can be detected solely through their differential light scattering profile using conventional flow cytometry. This same property reliably identified crystalline silica in association with primary monocytic cells in vitro using an imaging flow cytometry assay, where darkfield intensity measurements were able to detect crystalline silica concentrations as low as 2.5 μg/mL. Finally, we ultilised fresh whole blood as an exemplary complex biological matrix to test the technique. Even after the increased sample processing required to analyse cells within whole blood, imaging flow cytometry was capable of detecting and assessing silica-association to cells. As expected, in fresh whole blood exposed to crystalline silica, neutrophils and cells of the monocyte/macrophage lineage phagocytosed the particles. In addition to the use of this technique in in vitro exposure models, this method has the potential to be applied directly to ex vivo diagnostic studies and research models, where the identification of crystalline silica association with cells in complex biological matrices such as bronchial lavage fluids, alongside additional functional and phenotypic cellular readouts, is required.

Role of Nephronectin in Pathophysiology of Silicosis

Silicosis is a typical form of pneumoconiosis and is characterized as a type of lung fibrosis. Silica particles are captured and recognized upon by alveolar macrophages via the macrophage receptor with collagenous structure (MARCO) scavenger receptor, and thereafter the inflammasome is activated. Thereafter, various chemokines/cytokines play their roles to eventually form fibrosis. Additionally, silica particles chronically activate T helper cells which sets the background for the formation of silicosis-associated autoimmune disturbances. The occurrence and progression of lung fibrosis, the extracellular matrix-related molecules such as integrins and their ligands including fibronectin, vitronectin, laminin, and collagens, all play important roles. Here, the roles of these molecules in silicosis-related lung fibrosis are reviewed from the literature. Additionally, the measurement of serum nephronectin (Npnt), a new member of the integrin family of ligands, is discussed, together with investigations attempting to delineate the role of Npnt in silica-induced lung fibrosis. Serum Npnt was found to be higher in silicosis patients compared to healthy volunteers and seems to play a role in the progression of fibrosis with other cytokines. Therefore, serum Npnt levels may be employed as a suitable marker to monitor the progression of fibrosis in silicosis patients.

Silica Particles Mediate Phenotypic and Functional Alteration of Dendritic Cells and Induce Th2 Cell Polarization

During silicosis, immune cells, including macrophages, T cells, B cells, and NK cells, participate in fibrosis development through alteration of the immune status. Dendritic cells (DCs) are professional antigen-presenting cells (APCs) with a key role in initiating immune responses and sustaining immune tolerance to maintain homeostasis. The relative contribution of DCs to silicosis progression is not well-documented. In the current study, we investigated the phenotypic and functional alterations of peripheral blood mononuclear cell (PBMC)-derived DCs of Sprague-Dawley (SD) rat during immune responses to silica exposure. We established models for direct and indirect exposure of DCs to silica by either treating DCs with silica or coculturing them with alveolar macrophages (AMs) treated with silica, respectively. The functional activity of DCs was analyzed by measuring their expression of costimulatory molecules, fluorescent microparticle uptake, cytokine production, and ability to mediate T cell polarization in vitro. In vivo, we demonstrated that silica could induce DC migration in response to silica exposure. Our results show that cytokine production by DCs was increased in response to direct silica direct exposure, while indirect silica exposure led to reduced cytokine levels. Moreover, the phagocytic capacity of DCs increased in cocultures after silica exposure. Gene and protein expression analyses showed that silica exposure altered the expression levels of Toll-like receptor pathway proteins and inflammatory factors. DC surface expression of the costimulatory molecules, CD80, CD86, and major histocompatibility complex, was inhibited by exposure to silica, which mediated a Th2-polarizing response in vitro. In rats, silica exposure induced migration of DCs from the peripheral blood into the alveoli. These results demonstrate that direct and indirect exposure to silica particles alter the phenotype and function of DCs, thereby regulating immune responses. Such changes may contribute to the development of silicosis by altering DC phenotype, function, and migration and by influencing the balance between Th1 and Th2 cells.

Effects of Silicon Compounds on Biomineralization, Osteogenesis, and Hard Tissue Formation

Bioinspired stem cell-based hard tissue engineering includes numerous aspects: The synthesis and fabrication of appropriate scaffold materials, their analytical characterization, and guided osteogenesis using the sustained release of osteoinducing and/or osteoconducting drugs for mesenchymal stem cell differentiation, growth, and proliferation. Here, the effect of silicon- and silicate-containing materials on osteogenesis at the molecular level has been a particular focus within the last decade. This review summarizes recently published scientific results, including material developments and analysis, with a special focus on silicon hybrid bone composites. First, the sources, bioavailability, and functions of silicon on various tissues are discussed. The second focus is on the effects of calcium-silicate biomineralization and corresponding analytical methods in investigating osteogenesis and bone formation. Finally, recent developments in the manufacturing of Si-containing scaffolds are discussed, including in vitro and in vivo studies, as well as recently filed patents that focus on the influence of silicon on hard tissue formation.

Search for biomarkers of asbestos exposure and asbestos-induced cancers in investigations of the immunological effects of asbestos

The immunological effects of asbestos exposure on various lymphocytes such as the regulatory T cell (Treg), responder CD4+ T helper cell (Tresp), CD8+ cytotoxic T lymphocytes (CTL), and natural killer (NK) cells were investigated. Results show that asbestos exposure impairs antitumor immunity through enhancement of regulatory T cell function and volume, reduction of CXCR3 chemokine receptor in responder CD4+ T helper cells, and impairment of the killing activities of CD8+ cytotoxic T lymphocytes (CTL) and NK cells. These findings were used to explore biological markers associated with asbestos exposure and asbestos-induced cancers and suggested the usefulness of serum/plasma IL-10 and TGF-β, surface CXCR3 expression in Tresp, the secreting potential of IFN-γ in Tresp, intracellular perforin level in CTL, and surface expression NKp46 in NK cells. Although other unexplored cytokines in serum/plasma and molecules in these immunological cells, including Th17, should be investigated by experimental procedures in addition to a comprehensive analysis of screening methods, biomarkers based on immunological alterations may be helpful in clinical situations to screen the high-risk population exposed to asbestos and susceptible to asbestos-related cancers such as mesothelioma.

Silicosis, then microscopic polyangiitis-antineutrophil cytoplasmic antibodies-associated vasculitis may be work-related disease in patients with silicosis

A 74-year-old man with silicosis was admitted to the hospital because of prolonged fever. After referral to internal medicine for persistent fever and renal dysfunction, workup revealed antineutrophil cytoplasmic antibodies (ANCA) positivity. He was diagnosed with microscopic polyangiitis (MPA). After treatment with immunosuppressive therapy, his condition improved. Herein, we discuss silica exposure and the risk of ANCA-associated vasculitis (AAV), particularly in terms of work-related diseases. Silica exposure is a notorious risk factor for developing AAV, which is potentially lethal when not identified. When we see a silicosis patient with new-onset prolonged fever and generalized fatigue, AAV should be taken into consideration. This case report provides beneficial information to reliably assess patients at high risk of developing AAV in primary care settings.

Clinical evaluation of CENP-B and Scl-70 autoantibodies in silicosis patients

Silicosis patients (SIL) suffer from respiratory disorders and dysregulation of autoimmunity. Frequent complications such as rheumatoid arthritis, systemic sclerosis (SSc) and vasculitis are known in SIL. Furthermore, we reported previously that some SIL exhibited better respiratory conditions in association with a worse immunological status. In this study, the clinical roles of anti-CENP-B and Scl-70 autoantibodies in SIL were analyzed. The titer index (Log10) of anti-CENP-B autoantibody in SIL was higher than that of healthy volunteers (HV), and that of SSc was higher than those of HV and SIL. This titer index was positively correlated with an assumed immune status of 1 for HV, 2 for SIL, and 3 for SSc. Moreover, although factor analysis revealed that the titer index of the anti-CENP-B autoantibody formed the same factor with the anti-Scl-70 autoantibody, IgG value and age in SIL cases, another extracted factor indicated that the IgA value and anti-Scl-70 antibody were positively related, but anti-CENP-B showed an opposite pattern in the results of the factor analysis. These findings indicated that the titer index of anti-CENP-B autoantibody may be a biomarker for dysregulation in SIL cases. Future clinical follow-up of SIL may therefore require both respiratory and immunological assessment.

Preventing the development of SLE: identifying risk factors and proposing pathways for clinical care

Although challenging, developing evidence-based approaches to an early and accurate diagnosis of systemic lupus erythematosus is a key approach to preventing disease and lupus-associated morbidity and mortality. Advances in our understanding of preclinical and incomplete lupus erythematosus have enabled the identification of risk factors that may predict disease and the development of potential strategies aimed at primary prevention. Emerging data support the notion that there is a temporal disease progression from initial asymptomatic autoimmunity (preclinical lupus) through early clinical features of the disease (incomplete lupus erythematosus) to finally becoming fully classifiable systemic lupus erythematosus (complete lupus erythematosus). Here, we review the demographic, clinical, biomarker as well as genetic and environmental features that are reported to increase the risk of disease progression. Based on these risk factors, we propose a clinical care pathway for patients with early disease. We envisage that such a pathway, through early identification of disease, may improve patient outcomes, while reducing health care costs.

Mannan-binding lectin, a serum collectin, suppresses T-cell proliferation via direct interaction with cell surface calreticulin and inhibition of proximal T-cell receptor signaling

Mannan binding lectin (MBL), initially reported to activate the complement pathway, is also known to be involved in the pathogenesis of autoimmune diseases. We report a thus far unknown function of MBL as a suppressor of T-cell activation. MBL markedly inhibited T-cell proliferation induced by anti-CD3 and anti-CD28 antibodies. Moreover, the presence of MBL during T-cell priming interfered with proximal T-cell receptor signaling by decreasing phosphorylation of Lck, ZAP-70, and LAT. MBL bound to T cells through interaction between the collagen-like region of MBL and calreticulin (CRT) expressed on the T-cell surface. The neutralizing antibody against CRT abrogated MBL-mediated suppression of T-cell proliferation, suggesting that MBL down-modulates T-cell proliferation via cell surface CRT. We further demonstrated that the feature of MBL-mediated T-cell suppression is shared by other serum collectins (e.g., C1q and collectin 11). The concentrations of MBL correlated negatively with in vivo T-cell activation status in patients with early-stage silicosis. Furthermore, MBL efficiently inhibited activation and proliferation of autoreactive T cells derived from patients with silicosis, indicating that MBL serves as a negative feedback control of the T-cell responses.-Zhao, N., Wu, J., Xiong, S., Zhang, L., Lu, X., Chen, S., Wu, Q., Wang, H., Liu, Y., Chen, Z., Zuo, D. Mannan-binding lectin, a serum collectin, suppresses T-cell proliferation via direct interaction with cell surface calreticulin and inhibition of proximal T-cell receptor signaling.

Accelerated cell cycle progression of human regulatory T cell-like cell line caused by continuous exposure to asbestos fibers

Asbestos exposure causes malignant tumors such as lung cancer and malignant mesothelioma. Based on our hypothesis in which continuous exposure to asbestos of immune cells cause reduction of antitumor immunity, the decrease of natural killer cell killing activity with reduction of NKp46 activating receptor expression, inhibition of cytotoxic T cell clonal expansion, reduced CXCR3 chemokine receptor expression and production of interferon-γ production in CD4+ T cells were reported using cell line models, freshly isolated peripheral blood immune cells from health donors as well as asbestos exposed patients such as pleural plaque and mesothelioma. In addition to these findings, regulatory T cells (Treg) showed enhanced function through cell-cell contact and increased secretion of typical soluble factors, interleukin (IL)-10 and transforming growth factor (TGF)-β, in a cell line model using the MT-2 human polyclonal T cells and its sublines exposed continuously to asbestos fibers. Since these sublines showed a remarkable reduction of FoxO1 transcription factor, which regulates various cell cycle regulators in asbestos-exposed sublines, the cell cycle progression in these sublines was examined and compared with that of the original MT-2 cells. Results showed that cyclin D1 expression was markedly enhanced, and various cyclin-dependent kinase-inhibitors were reduced with increased S phases in the sublines. Furthermore, the increase of cyclin D1 expression was regulated by FoxO1. The overall findings indicate that antitumor immunity in asbestos-exposed individuals may be reduced in Treg through changes in the function and volume of Treg.

Diagnosis of perinuclear anti-neutrophil cytoplasmic antibody-associated microscopic polyangiitis in silicotics: case report

Background

An association between silica exposure and autoimmune diseases including rheumatoid arthritis, systemic sclerosis, systemic lupus erythematosus, and anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis has been made.

Case presentation

A 56-year-old male presented with silicosis and had an occupational history of precious metal processing for 30 years and a 30 pack-year smoking history. The patient was diagnosed with pneumoconiosis and received compensation. No other complications were reported for pneumoconiosis. The patient suddenly presented with a non-specific headache for several days and microscopic hematuria was identified upon examination in the outpatient clinic. Following several weeks, the patient presented with aggravated dyspnea and hemoptysis, and his Modification of Diet in Renal Disease estimated glomerular filtration rate indicated acute kidney injury. Diagnostic analysis revealed perinuclear ANCA-associated microscopic polyangiitis (p-ANCA-associated MPA).

Conclusion

Exposure to silica dust was likely one of the cause of p-ANCA-associated MPA. Possible pathogenic mechanisms of autoimmune diseases in silicotics and emphasis of the necessity for early diagnosis are discussed.

Two Cases of Tsunami Dust Pneumonia: Organizing Pneumonia Caused by the Inhalation of Dried Tsunami Sludge after the 2011 Great East Japan Earthquake

We report two cases of organizing pneumonia (OP) secondary to the inhalation of the dried tsunami sludge which formed during the 2011 Great East Japan Earthquake and the consequent tsunami. After the disaster, both of these patients had been engaged in the restoration work. About half a month later, they developed shortness of breath and pulmonary infiltrates. These patients were diagnosed with interstitial pneumonia. Their biopsy specimens revealed multifocal peribronchiolitis and OP. An electron probe microanalysis of these specimens demonstrated the presence of elements from the earth's crust in the inflammatory lesions. These two cases indicate that exposure to dried tsunami sludge can cause OP.

Environmental factors and human health: fibrous and particulate substance-induced immunological disorders and construction of a health-promoting living environment

Among the various scientific fields covered in the area of hygiene such as environmental medicine, epidemiology, public health and preventive medicine, we are investigating the immunological effects of fibrous and particulate substances in the environment and work surroundings, such as asbestos fibers and silica particles. In addition to these studies, we have attempted to construct health-promoting living conditions. Thus, in this review we will summarize our investigations regarding the (1) immunological effects of asbestos fibers, (2) immunological effects of silica particles, and (3) construction of a health-promoting living environment. This review article summarizes the 2014 Japanese Society for Hygiene (JSH) Award Lecture of the 85th Annual Meeting of the JSH entitled "Environmental health effects: immunological effects of fibrous and particulate matter and establishment of health-promoting environments" presented by the first author of this manuscript, Prof. Otsuki, Department of Hygiene, Kawasaki Medical School, Kurashiki, Japan, the recipient of the 2014 JSH award. The results of our experiments can be summarized as follows: (1) asbestos fibers reduce anti-tumor immunity, (2) silica particles chronically activate responder and regulatory T cells causing an unbalance of these two populations of T helper cells, which may contribute to the development of autoimmune disorders frequently complicating silicosis, and (3) living conditions to enhance natural killer cell activity were developed, which may promote the prevention of cancers and diminish symptoms of virus infections.

Association between environmental exposures and granulomatosis with polyangiitis in Canterbury, New Zealand

Introduction

Granulomatosis with polyangiitis (GPA) is a rare systemic vasculitis. While aetiology is unknown the prominent respiratory involvement suggests inhaled antigens may be involved. The aim of this study was to identify environmental risk factors associated with GPA in Canterbury, New Zealand.

Methods

A case-controlled study was undertaken. All GPA cases fulfilled American College of Rheumatology (ACR), Chapel Hill Consensus Criteria (CHCC) or the European Medicines Agency (EMA) criteria. Each case was gender matched with four controls - 2 musculoskeletal (osteoarthritis or fracture) and 2 respiratory (asthma or chronic obstructive pulmonary disease). One musculoskeletal control and one respiratory control were age matched with the case at the time of the interview (interview) and the remaining two controls were age matched at the time their case experienced the first symptom of vasculitis (index). A structured questionnaire to assess potential environmental agents was administered without blinding for case/control status. Data were analyzed using conditional logistic regression to allow for the individual matching of cases and controls to assess for association between environmental factors and GPA.

Results

49 cases and 196 controls were recruited. 53 % were male and the mean ± standard deviation (SD) age of the cases was 64.9 ± 12.4 years, interview controls 65.1 ± 12.4.years and index controls 53.9 ± 14.5 years. Any reported exposure to dust (specifically silica and grain dust) was associated with GPA, odds ratio (OR) 3.6 (95 % confidence interval (CI); 1.5–8.3, p = 0.003). Occupation as a farm worker was associated with GPA OR 3.43 (1.5–7.5, p = 0.002). Specific gardening activities were associated with GPA including digging (OR 3.2; 1.4–7.0; p = 0.003), mowing (OR 2.7; 1.3–5.8; p = 0.008) and planting (OR 2.6; 1.2–5.5; p = 0.013).

Conclusion

We have replicated findings from northern hemisphere studies identifying dust exposure as well as farm exposure as risk factors for the development of GPA. We have shown activities associated with exposure to inhaled antigens, in particular those related to farming or gardening activities may increase the risk of GPA.

Enhancement of regulatory T cell-like suppressive function in MT-2 by long-term and low-dose exposure to asbestos

Asbestos exposure causes lung fibrosis and various malignant tumors such as lung cancer and malignant mesothelioma. The effects of asbestos on immune cells have not been thoroughly investigated, although our previous reports showed that asbestos exposure reduced anti-tumor immunity. The effects of continuous exposure of regulatory T cells (Treg) to asbestos were examined using the HTLV-1 immortalized human T cell line MT-2, which possesses a suppressive function and expresses the Treg marker protein, Foxp3. Sublines were generated by the continuous exposure to low doses of asbestos fibers for more than one year. The sublines exposed to asbestos showed enhanced suppressive Treg function via cell-cell contact, and increased production of soluble factors such as IL-10 and transforming growth factor (TGF)-β1. These results also indicated that asbestos exposure induced the reduction of anti-tumor immunity, and efforts to develop substances to reverse this reduction may be helpful in preventing the occurrence of asbestos-induced tumors.

Prospective risk of rheumatologic disease associated with occupational exposure in a cohort of male construction workers

BACKGROUND

The association between occupational exposure and autoimmune disease is well recognized for silica, and suspected for other inhalants. We used a large cohort to estimate the risks of rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, and dermatomyositis associated with silica and other occupational exposures.

METHODS

We analyzed data for male Swedish construction industry employees. Exposure was defined by a job-exposure matrix for silica and for other inorganic dusts; those with other job-exposure matrix exposures but not to either of the 2 inorganic dust categories were excluded. National hospital treatment data were linked for International Classification of Diseases, 10(th) Revision-coded diagnoses of rheumatoid arthritis (seronegative and positive), systemic lupus erythematosus, systemic sclerosis, and dermatomyositis. The 2 occupational exposures were tested as independent predictors of prospective hospital-based treatment for these diagnoses using age-adjusted Poisson multivariable regression analyses to calculate relative risk (RR).

RESULTS

We analyzed hospital-based treatment data (1997 through 2010) for 240,983 men aged 30 to 84 years. There were 713 incident cases of rheumatoid arthritis (467 seropositive, 195 seronegative, 51 not classified) and 128 cases combined for systemic lupus erythematosus, systemic sclerosis, and dermatomyositis. Adjusted for smoking and age, the 2 occupational exposures (silica and other inorganic dusts) were each associated with increased risk of rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, and dermatomyositis combined: RR 1.39 (95% confidence interval [CI], 1.17-1.64) and RR 1.31 (95% CI, 1.11-1.53), respectively. Among ever smokers, both silica and other inorganic dust exposure were associated with increased risk of rheumatoid arthritis (RRs 1.36; 95% CI, 1.11-1.68 and 1.42; 95% CI, 1.17-1.73, respectively), while among never smokers, neither exposure was associated with statistically significant increased risk of rheumatoid arthritis.

CONCLUSION

This analysis reaffirms the link between occupational silica and a range of autoimmune diseases, while also suggesting that other inorganic dusts may also impart excess risk of such disease.

Sjögren's Syndrome and Silicosis - a Case Report

Sjögren’s syndrome is an autoimmune disease of unknown etiology where immune response to self-antigens is believed to result from interactions between genetic and environmental factors. We describe the case of a patient who has been diagnosed with Sjögren’s syndrome based on typical clinical and immunological parameters. The clinical picture was dominated by the respiratory symptoms, and radiographic and multislice computed tomography examination of the chest showed certain changes characteristic of pneumoconiosis. Given that the patient has worked in a foundry where he has been exposed to the silica dust, he was subject to examination by occupational health specialists under the suspicion of lung silicosis, who confirmed the silicosis. This case report points to the possible connection between a professional exposure to silica and Sjögren’s syndrome. Occupational exposure to silica is a possible risk factor for the development of autoimmune diseases, and in the evaluation of patients with connective tissue diseases it is important to consider work-related history.

Shoulder ring complaints as a rare first symptom of malignant pleural mesothelioma

The prevalence of malignant pleural mesothelioma is often encountered in the areas highly exposed to asbestos. The aim of this paper was a retrospective analysis of shoulder pain as a rare, first symptom of pleural mesothelioma, which constitutes an interdisciplinary diagnostic problem concerning both orthopedics and pulmonology. The research was based on a retrospective review of the patients' medical records. The considered period of time included the years 2006-2012. The study group included a total of 49 patients. Seven patients (14.3%) presented a complain of shoulder pain, as the first symptom of mesothelioma. The remaining 42 mesothelioma patients, without this symptom, constituted a reference group. The intensity of shoulder pain was, on average, 4/10 on an analog scale. A concomitant limitation of mobility was observed in five out of the seven subjects. In one case, limitation of motion and dysfunction of the shoulder joint were at an advanced stage. Neuralgia of upper limbs was found in two cases. We conclude that shoulder pain may be a manifesting symptom of malignant pleural mesothelioma. The neoplasm appears to have a pleiotropic effect on human body, reflected in different ways of its primary manifestation which may also include the motor system.