Search

Occupational silica exposure caused a serious disease burden of silicosis. There is currently a lack of sensitive and effective biomarkers for silicosis, and the pathogenesis of silicosis is unclear. Exosomes were significant in the pathogenesis of silicosis, and our study was carried out from exosomal proteomics and cytokine analysis. Firstly, the plasma levels of cytokines were detected using a Luminex multiplex assay, and the results indicated that the plasma levels of TNF-α, IL-6, CCL2, CXCL10, and PDGF-AB were significantly higher in silicosis patients than in silica-exposed workers and controls (p < 0.05). After correlation analysis, the plasma levels of cytokines were positively correlated with exosomal protein concentration. Secondly, data-independent acquisition (DIA) was performed on plasma-derived exosomes in the screening population, which identified 88, 151, 293, and 53 differentially expressed proteins (DEPs) in exposure/control, silicosis/control, silicosis/exposure, and silicosis stage Ⅲ/silicosis stage Ⅰ groups respectively. After parallel reaction monitoring (PRM) in an independent verification population, the results indicated that the changing trend of 15 DEPs was coincident in screening and verification results. The result of correlation analysis indicated that the plasma level of TNF-α was negatively correlated with the expression of exosomal DSP, KRT78, SERPINB12, and CALML5. The AUC of combined determination of TNF-α and CALML5 reached 0.900, with a sensitivity of 0.714 and a specificity of 0.933. Overall, our study revealed the exosomal proteomic profiling of silicosis patients, silica-exposed workers, and controls, indicating that exosomes were significant in the pathogenesis of silicosis. It also revealed that the combined of the plasma levels of cytokines and the expression of exosomal DEPs could increase determination efficiency. This study provided directions for the development of silicosis biomarkers and a scientific basis for the pathogenesis research of silicosis in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Introduction: Silicosis is an irreversible and incurable disease. Preventive measures to eliminate exposure are the only effective way to reduce morbidity and mortality. In such situations, having a biomarker for early diagnosis or to predict evolution would be very useful in order to improve control of the disease. The elevation of serum angiotensin-converting enzyme (sACE) in silicosis has been described in previous studies, although its relationship with severity and prognosis is not clear., Aims: To determine the levels of sACE in a cohort of patients with exposure to silica dust with and without silicosis, and to assess their impact on the prognosis of the aforementioned patients., Method: Prospective observational study on patients treated in a silicosis clinic from 2009 to 2018. sACE levels and pulmonary function tests were performed. Radiological progression was assessed in patients who had already had 2 X-rays of the thorax and / or two CT scans with at least a 1-year interval, from the time of inclusion in the study., Results: A total of 413 cases of silicosis were confirmed, as well as 73 with exposure to silica dust but without silicosis. The mean sACE level for healthy subjects was 27.5±7.3U/L, for exposed patients without silicosis it was 49.6±24.2U/L, for simple silicosis it was 57.8±31,3U/L and for complicated silicosis it was 74.5±38.6U/L. Patients with a higher sACE generally progressed radiologically during follow-up (73.3±38.0 vs. 60.4±33.7; p<.001) and so the category of silicosis changed (73,9±38.1 vs. 62.5±34.6; p<.021)., Conclusions: sACE was elevated in patients with silicosis, and the greater its severity, the higher it was, which is associated with disease progression measured radiologically or as a category change of silicosis., (Copyright © 2022 Sociedade Portuguesa de Pneumologia. Published by Elsevier España, S.L.U. All rights reserved.)

Silicosis caused by engineered stone (ES-silicosis) is an emerging worldwide issue characterized by inflammation and fibrosis in the lungs. To our knowledge, only a few reports have investigated leukocyte/lymphocyte subsets in ES-silicosis patients. The present study was designed to explore the proportions of the main lymphocyte subsets in ES-silicosis patients stratified into two groups, one with simple silicosis (SS) and the other with a more advanced state of the disease, defined as progressive massive fibrosis (PMF). The proportions of B (memory and plasmablasts) cells, T (helper, cytotoxic, regulatory) cells, and natural killer (NK) (regulatory and cytotoxic) cells were investigated by multiparameter flow cytometry in 91 ES-silicosis patients (53 SS patients and 38 PMF patients) and 22 healthy controls (HC). Although the total number of leukocytes did not differ between the groups studied, lymphopenia was observed in patients compared to healthy controls. Compared with those in healthy controls, the proportions of memory B cells, naïve helper T cells, and the CD4 + /CD8 + T cells' ratio in the peripheral blood of patients with silicosis were significantly decreased, while the percentages of plasma cells, memory helper T cells, and regulatory T cells were significantly increased. For the NK cell subsets, no significant differences were found between the groups studied. These results revealed altered cellular immune processes in the peripheral blood of patients with ES-silicosis and provided further insight into silicosis pathogenesis.

Objective: To investigate the influence of silica exposure on the expression of connective tissue growth factor (CTGF), transforming growth factor beta-1 (TGF- β 1), and platelet-derived growth factor (PDGF) in lung silicosis rat., Methods: Wistar rats were divided into an experimental group and a control group. In the experimental group, rats were exposed to silica by intratracheal instillation. In the control group, rats were exposed to physiological saline by intratracheal instillation. After 45 days, we compared the level of fibrosis and CTGF, TGF- β 1, and PDGF in the lungs by immunohistochemistry or reverse transcription-polymerase chain reaction between the two groups., Results: The results showed that the expression levels of CTGF, TGF- β 1, and PDGF mRNA were significantly higher in the experimental group than those in the control group ( P < 0.05). The positive staining of CTGF, TGF- β 1, and PDGF mRNA was found in the cytoplasm, especially in the silicotic nodules of the hyalinisation section and cell endochylema of the alveolar macrophages, type II pneumonocytes, and lung tracheal epithelium. There were significantly positive correlations between CTGF, TGF- β 1, and PDGF expressions ( P < 0.05). A protein-protein interaction analysis showed interactions between TGF- β 1, CTGF, and PDGF., Conclusions: TGF- β /CTGF signaling pathway plays an important role in silicosis. Silicon dioxide exposure can induce the expression of CTGF, TGF- β 1, and PDGF., Competing Interests: All of the authors had no any personal, financial, commercial, or academic conflicts of interest separately., (Copyright © 2021 Jie Jiao et al.)

Silicosis is an irreversible, incurable and progressive occupational disease caused by prolonged exposure to crystalline-silica dust while working in the relevant industries. Conventionally diagnosis is done by chest radiology, often in an advanced stage as early symptoms often go unnoticed. Early detection and necessary intervention (secondary prevention) could be a realistic possible control strategy for controlling silicosis as no effective treatment is available to stop and/or reverse the pathological process. Additionally, these patients are also vulnerable to pulmonary tuberculosis, which often becomes difficult to treat and with uncertain treatment outcome. Considering India has a huge burden of silicosis and silico-tuberculosis, a rapid and inexpensive screening method was realized to be an urgent need for early detection of silicosis among silica dust exposed workers. Serum club cell protein 16 (CC16) is evidenced to be a useful proxy screening marker for early detection of silicosis as evidenced from the recent research work of ICMR-National Institute of Occupational Health (ICMR-NIOH), India. In this study a lateral-flow assay for semi-quantitative estimation of serum CC16 level was developed. The detection was performed using gold nanoparticles conjugated anti-CC16 monoclonal antibodies. A sum of 106 serum samples was tested to do the performance evaluation of the assay. A concentration of 6 ng/ml or less produced one band, 6.1-9 ng/ml produced two bands, while more than 9 ng/ml produced all the three bands at the test zone. The sensitivity of the assay was 100% while the specificity was 95%. This assay may be used as a sensitive tool for periodic screening of silica dust exposed vulnerable workers for early detection of silicosis in them., (© 2021. The Author(s).)

Silicosis is a diffuse interstitial lung disease caused by sustained inhalation of silica and silicates. Several cytokines are activated by their inhalation and can mediate the process of pulmonary fibrosis. The identification of biomarkers could allow an early diagnosis before the development of radiological alterations and help monitor the evolution of patients. The objetive of this study was to determine the clinical significance of specific biomarkers, to estimate their association with the development, severity and/or progression of silicosis, and identify determinants of this evolution. We conducted a prospective observational study in patients attending the pulmonology clinic from 2009 to 2018. Serum levels of the following inflammatory mediators were assessed: interleukin-6 (IL-6), interleukin 2 receptor subunit alpha (IL2R) interleukin 1 beta (IL1B), interleukin-8 (IL-8), tumour necrosis factor-alpha (TNF-α), transforming growth factor-beta1 (TGF-β1), alpha-1 antitrypsin (AAT), C-reactive protein (CRP), lactate dehydrogenase (LDH) and ferritin in subjects exposed to silica, with and without silicosis. Association between those inflammatory mediators with lung function measurements and radiological severity of disease and their impact on prognosis were analysed. 337 exposed to silica (278 with silicosis) and 30 subjects in the control group were included. IL-8, α1AT, ferritin, CRP and LDH levels were higher in silicosis than in those exposed to silica without silicosis. IL-8, LDH and AAT levels were associated with progression of silicosis and IL-6, IL-8, LDH, AAT, ferritin, and CRP with vital status. The results of the ROC analysis indicated the potential of IL-8 as a biomarker in the presence of silicosis and for the prediction of mortality.

Background: Silicosis is a progressive pneumoconiosis characterized by interstitial fibrosis following exposure to silica dust. The role of metabolic dysregulation in the pathogenesis of silicosis has not been investigated in detail. This study aimed to identify different metabolic features in the plasma of patients with silicosis and dust-exposed workers without silicosis in metabolomics studies., Methods: Patients with silicosis, dust-exposed workers (DEWs) without silicosis and age-matched healthy controls were recruited in a case-control study. The metabolomics analyses by ultra-high performance liquid chromatography-mass spectrometry were conducted. Distinct metabolic features (DMFs) were identified in the pilot study and were validated in the validation study. The enriched signalling pathways of these DMFs were determined. The ability of DMFs to discriminate among the groups was analysed through receiver operating characteristic (ROC) curves. The correlations between DMFs and clinical features were also explored., Results: Twenty-nine DMFs and 9 DMFs were detected and had the same trend in the pilot study and the validation study in the plasma of the DEW and silicosis groups, respectively. Sphingolipid metabolism was the major metabolic pathway in the DEWs, and arginine and proline metabolism was associated with silicosis. Twenty DMFs in the DEWs and 3 DMFs in the patients with silicosis showed a discriminatory ability with ROC curve analysis. The abundance of kynurenine was higher in Stage III silicosis than in Stage I or Stage II silicosis. L-arginine and kynurenine were both negatively correlated with the percentage of forced vital capacity predicted in silicosis., Conclusions: Distinct metabolic features in the plasma of DEWs and the patients with silicosis were found to be different. Sphingolipid metabolism and arginine and proline metabolism were identified as the major metabolic pathway in the DEW and silicosis groups, respectively. L-arginine and kynurenine were correlated with the severity of silicosis.

Silicosis is a devastating disease caused by inhalation of silica dust that leads to inflammatory cascade and then scarring of the lung tissue. Increasing evidences indicate that soluble receptor for advanced glycation end products (sRAGE) is involved in inflammatory diseases. However, no data on the possible relationship between sRAGE and inflammation of silicosis are available. In this study, serum from subjects with silicosis ( n = 59) or from healthy controls (HC, n = 14) was analyzed for the secretion of sRAGE, tumor necrosis factor- α (TNF- α ), interleukin-1 β (IL-1 β ), interleukin-6 (IL-6), transforming growth factor- β 1 (TGF- β 1), and oxidized low-density lipoprotein (ox-LDL). The associations between sRAGE and cytokines and ox-LDL and lung function were assessed by Pearson's correlation analyses. Mean levels of serum sRAGE were lower in silicosis than those in controls ( p < 0.05). The subjects who had a longer term of occupational exposure had higher levels of sRAGE ( p < 0.05). The secretion of TNF- α , IL-1 β , IL-6, TGF- β 1, and ox-LDL was significantly higher in the silicosis group than that in the HC group ( p < 0.05). Furthermore, the levels of sRAGE were negatively correlated with TNF- α , IL-6, IL-1 β , and ox-LDL. There is no correlation between sRAGE and TGF- β 1 and lung function. The optimal point of sRAGE for differentiating silicosis from healthy controls was 14250.02 pg/ml by ROC curve analysis. A decrease in serum sRAGE and its association with inflammatory response might suggest a role for sRAGE in the pathogenesis of silicosis., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2020 Heliang Liu et al.)

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.

Objective: This study aims to investigate the changes in CD3 + , CD4 + and CD8 + expression in cells in peripheral blood of silicosis patients, and observe the immunoregulatory effect of thymalfasin., Methods: A total of 80 silicosis patients were enrolled in the study, randomly divided into two groups: treatment group and control group (n=40, each group). In addition, 40 healthy adults, who underwent physical examinations in our hospital, were enrolled into the health examination group. Patients in the control group and treatment group were given anti-infection treatment, according to their conditions. Patients in the treatment group additionally received thymalfasin. Then, the number of peripheral blood T lymphocyte subsets in subjects in all three groups before and after treatment was measured., Results: (1) Before treatment, CD3 + , CD4 + and CD8 + levels in cells were significantly lower in the treatment group and control group than in the health examination group, and the differences were statistically significant ( P <0.05). (2) In the treatment group, the number of CD4 + cells in peripheral blood was significantly higher after one week of treatment, when compared to that before treatment, and the difference was statistically significant ( P <0.05)., Conclusion: In silicosis patients, CD3 + , CD4 + and CD8 + cells in peripheral blood are decreased, and thymalfasin can significantly increase CD4 + cells in peripheral blood of silicosis patients., (© 2019 by the Association of Clinical Scientists, Inc.)

High-mobility group box-1 (HMGB-1) has been associated with fibrotic diseases. However, the role of HMGB-1 in silicosis is still uncertain. In this study, we conducted a case-control study involving 74 patients with silicosis and 107 age/gender-matched healthy controls in China. An Enzyme-linked immunosorbent assay (ELISA) was used to examine the concentrations of plasma HMGB-1 among all subjects. A logistic regression model and receiver operating characteristic curve (ROC) analysis were performed to assess the relationships between HMGB-1 and silicosis. We observed that plasma HMGB-1 concentrations were significantly increased in silicosis patients when compared with healthy controls ( p < 0.05). Each 1 ng/mL increase in plasma HMGB-1 was positively associated with increased odds of silicosis, and the odds ratio (OR) (95% confidence interval) was 1.86 (1.52, 2.27). Additionally, compared with subjects with lower HMGB-1 concentrations, increased odds of silicosis were observed in those with higher HMGB-1 concentrations, and the OR was 15.33 (6.70, 35.10). Nonlinear models including a natural cubic spline function of continuous HMGB-1 yielded similar results. In ROC analyses, we found that plasma HMGB-1 >7.419 ng/mL had 81.6% sensitivity and 80.4% specificity for silicosis, and the area under the curve (AUC) was 0.84. Our results demonstrated that elevated plasma HMGB-1 was positivity associated with increased OR of silicosis.

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.

Rationale: Phagocytosis of silicon dioxide (SiO 2 ) into lung cells causes an inflammatory cascade that results in fibroblast proliferation and migration, followed by fibrosis. Circular RNAs (circRNAs) are a subclass of non-coding RNAs detected within mammalian cells; however, researchers have not determined whether circRNAs are involved in the pathophysiological process of silicosis. The upstream molecular mechanisms and functional effects on cell apoptosis, proliferation and migration were investigated to elucidate the role of circRNAs in SiO 2 -induced inflammation in pulmonary macrophages. Methods: Primary cultures of alveolar macrophages from healthy donors and patients as well as the RAW264.7 macrophage cell line were used to explore the functions of circHECTD1 (HECT domain E3 ubiquitin protein ligase 1) in macrophage activation. Results: The results of the experiments indicated that 1) SiO 2 concomitantly decreased circHECTD1 levels and increased HECTD1 protein expression; 2) circHECTD1 and HECTD1 were involved in SiO 2 -induced macrophage activation via ubiquitination; and 3) SiO 2 -activated macrophages promoted fibroblast proliferation and migration via the circHECTD1/HECTD1 pathway. Tissue samples from silicosis patients confirmed the upregulation of HECTD1. Conclusions: Our study elucidated a link between SiO 2 -induced macrophage activation and the circHECTD1/HECTD1 pathway, thereby providing new insight into the potential use of HECTD1 in the development of novel therapeutic strategies for treating silicosis., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Background: Asbestosis and silicosis are progressive pneumoconioses characterized by interstitial fibrosis following exposure to asbestos or silica dust. We evaluated the potential diagnostic biomarkers for these diseases., Methods: The serum concentrations of Krebs von den Lungen-6 (KL-6), surfactant protein D (SP-D), and matrix metalloproteinase-2 (MMP-2), MMP-7, and MMP-9 were measured in 43 patients with asbestosis, 45 patients with silicosis, 40 dust-exposed workers (DEWs) without pneumoconiosis, and 45 healthy controls (HCs). Chest high-resolution computed tomography (HRCT) images were reviewed by experts blinded to the clinical data. According to the receiver operating characteristic (ROC) curve, the ideal level of each biomarker and its diagnostic sensitivity were obtained., Results: The serum KL-6 and MMP-2 concentrations were highest in patients with asbestosis, particularly in comparison with those in DEWs and HCs (P<0.05). The serum SP-D concentration was significantly higher in patients with asbestosis than in patients with silicosis, DEWs, and HCs (P<0.01), whereas no significant difference was noted among patients with silicosis, DEWs, and HCs. No significant difference in the serum MMP-7 or -9 concentration was found among patients with asbestosis, patients with silicosis, DEWs, or HCs. Among patients with asbestosis, the serum KL-6 concentration was significantly correlated with the lung fibrosis scores on HRCT and negatively correlated with the forced vital capacity (FVC) % predicted and diffusing capacity of the lung for carbon monoxide (DL CO ) % predicted. The serum SP-D and MMP-2 concentrations were negatively correlated with the DL CO % predicted (all P<0.05). The order of diagnostic accuracy according to the ROC curve was KL-6, SP-D, and MMP-2 in patients with asbestosis alone and in the combination of both patients with asbestosis and those with silicosis. The combination of all three biomarkers may increase the possibility of diagnosing asbestosis (sensitivity, 93%; specificity, 57%) and both asbestosis and silicosis (sensitivity, 83%; specificity, 62%)., Conclusions: KL-6, SP-D, and MMP-2 are available biomarkers for the adjuvant diagnosis of asbestosis and silicosis. The combination of all three biomarkers may improve the diagnostic sensitivity for asbestosis and silicosis.

Pulmonary silicosis is an irreversible and untreatable disease that is characterized by interstitial lesions and perpetual fibrosis in the lungs. This study was performed to determine whether mesenchymal stem cells (MSCs) and hepatocyte growth factor (HGF) could exhibit therapeutic effects on human silicosis. This non-randomized uncontrolled trial comprised four patients with pulmonary silicosis who had developed lung fibrosis and received autologous bone marrow MSCs previously transfected by a vector containing human HGF cDNA (MSCs/HGF). MSCs/HGF were intravenously administered weekly for three consecutive weeks at a dose of 2 x 10(6) cells/kg. Pulmonary function, high kilo-voltage chest X-ray radiography, computed tomography (CT) scan, and peripheral blood lymphocyte subset and serum IgG concentrations were evaluated after cell therapy. The treatment was found to be generally safe. Symptoms such as cough and chest distress gradually ameliorated at six months post-therapy, accompanied by the significant improvement of pulmonary function. The ratios of the peripheral CD4- and CD8- positive cell concentrations were increased (P < 0.05). Furthermore, the serum IgG levels in these patients were decreased and reached the normal range (P < 0.05). CT scans showed partial absorption of the nodular and reticulonodular lesions in the lungs during follow-up of at least 12 months. The effectiveness of this novel regimen observed in these patients suggests that a placebo-controlled clinical trial needs to be developed. This study carries trial registration No. NCT01977131 (ClinicalTrials.gov).

Silica particles and asbestos fibers, which are known as typical causatives of pneumoconiosis, induce lung fibrosis. Moreover, silicosis patients often complicate with autoimmune diseases, and asbestos-exposed patients suffer from malignant diseases such as pleural mesothelioma and lung cancer. We have been conducting experimental studies to investigate altered regulation of self-tolerance caused by silica exposure, including analyses using specimens such as plasma and immunocompetent cells obtained from silicosis patients, as a means of examining the supposition that silica exposure induces molecular and cellular biological alterations of immune cells. These approaches have resulted in the detection of several specific autoantibodies, alterations of CD95/Fas and its related molecules, and evidence of chronic activation of responder T cells and regulatory T cells following silica exposure. In this review, we present details of our investigations as an introduction to scientific approaches examining the immunological effects of environmental and occupational substances.

Prolonged exposure to silica dust causes an imbalance in the generation of free radicals and in the antioxidant system, thereby inducing oxidative stress. The antioxidant status of 113 silicosis patients and 116 control subjects without silicosis was examined. Serum superoxide dismutase (SOD) activity and serum levels of malondialdehyde (MDA) and glutathione (GSH) were significantly higher in silicosis patients than in controls. The GSH level in patients with stage I silicosis was higher than that in patients with other stages, but there was no difference in serum MDA level and SOD activity between disease stages. The GSH level of patients who worked with air drills was significantly lower than that of patients in other occupations, whereas the MDA level was significantly elevated in patients who used air drills. Serum SOD activity did not differ significantly according to the occupational group. It is concluded that the measurement of serum SOD, GSH and MDA levels could be beneficial in the clinical evaluation of serum antioxidant status in silicosis patients.

Angiogenesis has been implicated in the pathogenesis of interstitial lung diseases. A correlation between serum angiogenic cytokines level of patients with idiopathic pulmonary fibrosis and radiographic manifestations or functional pulmonary changes has been described, but the role of angiogenesis in the pathogenesis of other interstitial lung diseases such as silicosis and pulmonary Langerhans cell histiocytosis remains unclear. The aim of the study was to examine the effect of sera from silicosis and pulmonary Langerhans cell histiocytosis patients on angiogenesis induced by human mononuclear cells (MNC) in relation to pulmonary function. The study population consisted of 12 patients with silicosis, 12 patients with pulmonary Langerhans cell histiocytosis (PLH), and 14 healthy volunteers. Spirometry, whole-body plethysmography, static lung compliance (Cst), and diffusing capacity of the lung for CO (DL(CO)) were performed in all patients. As an angiogenic test, leukocyte induced angiogenesis assay according to Sidky and Auerbach was used. Sera from PLH patients exerted a significant inhibitory effect on angiogenesis (P<0.001). Sera from silicosis patients significantly (P<0.001) stimulated angiogenesis compared with sera from healthy donors. However, sera from healthy donors significantly stimulated the angiogenic activity of MNC compared with the control with PBS. The mean value of DL(CO) was significantly lower in the group of patients with PLH compared with patients with silicosis (P<0.05). A significant correlation between angiogenesis index and DL(CO) was observed (P<0.05). No significant correlation between the angiogenesis index and other functional parameters was found. Sera from interstitial lung diseases patients and healthy donors constitute a source of mediators modulating angiogenesis. Sera from silicosis patients stimulate neovascularization but sera from PLH patients exert an inhibitory effect on angiogenesis. A correlation between serum angiogenic activity and DL(CO) was found.

It is well established that patients with silicosis are at high risk for lung cancer; however, it is difficult to detect lung cancer by chest radiography during follow-up treatment of patients with silicosis because of preexisting diffuse pulmonary shadows. The purpose of this study is to evaluate the usefulness of detection of serum DNA methylation for early detection of lung cancer in silicosis. Serum samples from healthy controls (n = 20) and silicosis patients with (n = 11) and without (n = 67) lung cancer were tested for aberrant hypermethylation at the promoters of the DNA repair gene O(6)-methylguanine-DNA methyltransferase (MGMT), p16(INK4a), ras association domain family 1A (RASSF1A), the apoptosis-related gene death-associated protein kinase (DAPK) and retinoic acid receptor beta (RARbeta) by methylation-specific polymerase chain reaction. Aberrant promoter methylation in at least one of five tumor suppressor genes was detected more frequently in the serum DNA of silicosis patients with lung cancer than in that of patients without it (P = 0.006). Furthermore, the odds ratio of having lung cancer was 9.77 (P = 0.009) for those silicosis patients with methylation of at least one gene. Extended exposure to silica (>30 years) was correlated with an increased methylation frequency (P = 0.017); however, methylation status did not correlate with age, smoking history or radiographic findings of silicosis. These results suggest that testing for aberrant promoter methylation of tumor suppressor genes using serum DNA may facilitate early detection of lung cancer in patients with silicosis.

Susceptibility to silicosis and to disease severity is in part genetically determined. In this study, the role of IL-12B-3'UTR polymorphism in susceptibility and severity of silicosis and its influence on IL-12p40 and IL-12p70 serum level were investigated. The quantity of IL-12p40 and IL-12p70 was detected by enzyme-linked immunosorbent assay and the genotype of IL-12B was determined using the polymerase chain reaction-restriction fragment-length polymorphism method. We observed elevated IL-12p40 in contrast to IL-12p70 serum levels in a group of 62 silicosis patients compared with both control groups. In severe silicosis patients, we detected the highest IL-12p40 serum levels (129.1 +/- 67.7 pg mL(-1)); lower in patients with the moderate (94 +/- 41.6 pg mL(-1)), whereas in mild silicosis, the IL-12p40 levels (67 +/- 23.5 pg mL(-1)) was similar to these in healthy donors. According to IL-12B polymorphism, increased serum levels were observed in subjects with AA genotype (103.2 +/- 46.9 pg mL(-1)) compared to silicosis patients with AC genotype (82.7 +/- 38.3 pg mL(-1)). No significant differences of genotype and allele frequencies of the 3'UTR polymorphism were observed between silicosis patients and healthy controls. However, the heterozygous genotype was found approximately five times more frequently in patients with mild and moderate (48% and 52%) silicosis compared to patients with severe silicosis (11%), and that IL-12B polymorphism may contribute to silicosis severity rather than to susceptibility. Our data demonstrated that elevated serum IL-12p40, independently of IL-12p70 levels, is associated with severity of silicosis, and suggested that IL-12p40 profibrotic activity may contribute to silicosis severity.

Objective: Cement masons are known to have significant silica exposure, and silica exposure and silicosis are thought to increase risk of autoimmune disease. Because the mechanisms remain obscure, with inconclusive reports of systemic immune effects following silica exposure, our goal was to identify potential early markers of silica-related immunologic and respiratory effects., Methods: We conducted a cross-sectional study of cement mason apprentices and electrician (control) apprentices. Demographics, dust exposure history, symptoms, spirometry, exhaled nitric oxide, and blood (for immunoglobulins, cytokines, cell counts, and surface markers) were obtained from 11 cement mason apprentices and a comparison group of 21 electrician apprentices., Results: Masons had significantly higher (P < 0.05) masonry dust exposure (42 versus 9 dust-hour-years), serum interleukin-1beta (IL-1beta; 12 versus 9 pg/ml), IL-2 (20 versus 8 pg/ml), IL-4 (193 versus 67 pg/ml), IL-10 (44 versus 21 pg/ml), and interferon-gamma (139 versus 65 pg/ml) compared with electricians. In contrast, masons had significantly lower percentages of CD25+ (12% versus 20%) and CD69+ (4% versus 9%) lymphocytes., Conclusion: Mason apprentices had higher levels of serum proinflammatory cytokines and lower percentages of CD25+ and CD69+ lymphocytes than did electrician apprentices. These preliminary findings suggest that mason apprentices may be at greater risk of a systemic proinflammatory state that is potentially linked to immune dysregulation. Although distinct limitations of this preliminary data are recognized, this is consistent with early biologic effects leading to increased incidence of autoimmune disease among silica-exposed workers. Prospective studies are needed to validate these initial findings and clarify the temporal sequence of observed relationships.

An increased prevalence of autoimmune diseases such as rheumatoid arthritis has been demonstrated in silica-exposed patients. The aim of this study was to determine the peripheral blood lymphocyte phenotype in a population of silicotic workers employed in the slate mines of the district. Silicosis was assessed in 58 patients according to the International Labor Office's criteria. Clinical and biological data including flow cytometric evaluation of the lymphocyte subsets were compared with those from 41 healthy volunteers. The silicotic patients had a higher prevalence of autoimmune diseases (6/58 versus 0/41: P < 0.05) and of elevated antinuclear antibody titres compared to the control group. A very significant decrease of total lymphocyte count (P < 0.001) involving B, T and Natural Killer cells was found in silicotic patients as compared with matched healthy volunteers. A significant increase in the percentage of activated T cells (12.3%) was observed in the silicotic group as compared to 6.5% in the control group (P = 5 x 10(-5)). Our results show that in silicotic patients, the absolute number of circulating lymphocytes is diminished with an increased proportion of activated T cells. Whether these findings could predispose to the development of autoimmune disorders is discussed.

Certain patients with silicosis have been reported to exhibit immunological abnormalities such as the appearance of antinuclear antibodies and the occurrence of autoimmune diseases. Fas ligand (FasL) is a type II membrane protein which induces apoptosis by binding to its membrane receptor, Fas. FasL is converted to a soluble form by a metalloproteinase-like enzyme. We have already found serum soluble Fas (sFas) levels in silicosis patients as well as in patients with systemic lupus erythematosus (SLE) to be significantly higher than those in healthy volunteers. To examine further the role of the Fas/FasL system in silica-induced immunological abnormalities, we investigated serum soluble FasL (sFasL) levels in silicosis patients with no clinical symptoms of autoimmune diseases, using ELISA for sFasL. Although the serum sFasL levels in patients with SLE were significantly higher than those in healthy volunteers and showed a slight positive correlation with serum sFas levels, those in silicosis patients exhibited no significant difference from those in healthy volunteers, and there was no correlation with serum sFas levels. However, sFasL levels were elevated in silicosis patients with slight dyspnoea or normal PCO2 among various clinical parameters of silicosis. It may be speculated that the immunological disturbances presented by the abnormalities of apoptosis-related molecules in silicosis patients do not occur with a similar degree of respiratory involvement. Further studies are required to clarify which kinds of factors are involved in silicosis patients who exhibit immunological abnormalities.

To establish a new clinical index for immunological abnormalities occurring in silicosis, several clinical parameters related to Fas-mediated apoptosis; i.e., membrane Fas expression on peripheral blood lymphocytes (mFas), serum soluble Fas levels (sFas), serum soluble Fas ligand levels (sFasL), and soluble/membrane Fas mRNA expression ratios (s/mFas ExR) in peripheral blood mononuclear cells (PBMC) were investigated. Fifty-eight silicosis patients with no clinical symptoms of autoimmune diseases were the subjects of this study. Factor analysis was performed using 12 clinical parameters including four parameters related to Fas-mediated apoptosis. Two common factors were identified. Factor 1 which consisted of the following parameters; duration of exposure, symptomatic dyspnea, PO2, PCO2, and A-aDO2, should be designated as the respiratory factor for cases with silicosis. The parameters of factor 2 were serum IgG, sFas with high factor loading, titer of ANA, sFasL, and s/mFas ExR. These parameters of factor 2 are indicative of the immunological disorders occurring in silicosis cases. Some cases exhibited abnormalities in parameters of factor 2 but not factor 1. The factor analysis clearly demonstrated that the parameters related to Fas-mediated apoptosis should be the most beneficial for predicting the pre-clinical status of complicated autoimmune diseases in silicosis.

Soluble Fas (sFas) is produced as translation products of alternative mRNA splicing, and antagonizes the membranous Fas molecule in Fas/Fas ligand interactions. We investigated the serum sFas levels in 64 Japanese silicosis patients with no clinical symptoms of autoimmune diseases or malignant tumours, using ELISA for sFas. The serum sFas levels in the silicosis patients were significantly higher than those in healthy volunteers. Elevated serum sFas levels were also detected in patients with systemic lupus erythematosus but, unexpectedly, no difference was observed in sFas levels between progressive systemic sclerosis patients and healthy volunteers. On the other hand, there was no significant difference in the expression of Fas on peripheral blood lymphocytes between the patients with silicosis and age-matched healthy volunteers. These observations provided the first evidence that serum sFas levels are elevated in silicosis patients without clinical symptoms of autoimmune diseases or malignant tumours. It remains to be clarified whether patients with elevated sFas levels have a tendency to develop autoimmune diseases later, or whether some other distinct factor(s) is necessary to initiate the progression of autoimmune diseases.

Serum lactate dehydrogenase (LDH) activity, a marker of cell damage, is increased in several pulmonary disorders, especially when fibrosis is involved. In rats exposed to silica, high levels of LDH activity were found. A rise of serum LDH3 has been associated with lung tissue injury. The aim of this study was to investigate the serum LDH isoenzyme pattern after coal-dust exposure and the possible relation to pulmonary function tests. Ex-coalminers (n = 201), with a history of coal-dust exposure more than 20 yr ago, were admitted to the authors' hospital for a medical check-up and were included in the study. The serum LDH activity was found to be elevated in 79.1% of the ex-coalminers (634 +/- 245 U I-1). Moreover, in 196 of the 201 cases (97.5%), a high LDH3 level (31 +/- 4%) was demonstrated. A moderate negative relation was found between the forced expiratory volume in 1 s (FEV1) and the LDH activity (r = -0.26; P < 0.001), as well as between FEV1 and LDH3 activity (r = -0.23; P < 0.001), even in the subgroup (n = 42) with a normal LDH. All other liver function tests were within normal limits. These results suggest that coal-dust, even many years after the actual exposure, causes an increase in the total serum LDH activity and changes in the LDH-isoenzyme pattern, mainly characterized by a high LDH3 activity.

Objective: To determine the frequency and type of autoantibodies present in patients with systemic sclerosis (SSc) associated with an established environmental toxin., Methods: Clinical data and sera were available from 14 men with silica-associated SSc who had developed SSc after at least 2 years of exposure to silica at work. Controls included 27 men with silicosis without SSc. Autoantibodies were measured by immunodiffusion, immunoblotting, and functional inhibition of topoisomerase I (topo I)., Results: Nine of the 14 patients with silica-associated SSc had anti-topo I antibodies. All anti-topo I antibodies in the patients with silica-associated SSc and in 14 anti-topo I-positive patients with idiopathic SSc were directed at an active site of topo I, or at least sterically inhibited its function. One patient with silica-associated SSc had anticentromere antibodies. Unexpectedly, 2 patients with silicosis who had no symptoms of a connective tissue disease had autoantibodies to Ro/SS-A and La/SS-B autoantigens., Conclusion: Anti-topo I antibodies are the predominant autoantibodies present in silica-associated SSc. The generation of anti-topo I antibodies in genetically susceptible individuals may depend partly on the patient's sex and on the site of organ involvement, and may be triggered by silica particles acting as an immune adjuvant.

Silicosis is characterized by pulmonary fibrotic changes which consist primarily of an increase in collagen. In this study, anticollagen antibodies in the serum of 134 silicosis patients versus 40 normal subjects were examined and their relationship with immunoglobulin, autoantibodies, and procollagen III peptide (PIIIP) was investigated by enzyme-linked immunosorbent assay (ELISA). The mean levels of anti-human type I collagen (HI) and anti-human type III collagen (HIII) antibodies were significantly higher in the silicosis patients versus the normal subjects (P < 0.001). However, no differences were observed in the mean levels of anti-human type IV collagen (HIV) antibodies in the silicosis patients versus the normal subjects. Anticollagen antibodies in the sera of silicosis patients appear to be formed at an early stage of the disease. We observed a correlation between anticollagen antibodies and immunoglobulin. There was a tendency toward high values of anticollagen antibodies in the sera of patients positive for antinuclear antibodies (ANA) and rheumatoid factor (RF), both of which are autoantibodies. However, no correlation was observed between serum PIIIP and anticollagen antibodies. These observations suggest that, in silicosis, there is a relationship between anticollagen antibodies and immunoglobulins, as well as between anticollagen antibodies and autoantibodies. Measurement of anticollagen antibodies in the sera of silicosis patients offers a useful index for evaluating the prognosis of pulmonary fibrosis and autoimmune abnormality in silicosis.

A previous investigation has shown that family susceptibility and occupational and family histories have a decisive role in the development of byssinosis among workers exposed to flax dust. Results of investigation of silicosis in 814 male workers exposed to silica-bearing dust showed that family susceptibility has an important role in the development of silicosis among examined workers, and workers whose fathers had an occupational history of exposure to silica-bearing dust were more resistant to the development of the disease than those with non-exposed fathers. The degree of consanguinity of parents and individuals' blood groups, also, have a role. Workers with cousin parents were relatively highly susceptible to the development of silicosis as well as workers with blood groups "O" or "AB". It has been concluded that the investigated factors might have a role in the development of other occupational diseases and further investigations are indicated.

The relationship between rheumatoid arthritis and silicosis was studied by means of a case-control study in South African gold miners. One hundred and fifty seven miners with rheumatoid arthritis classified as "definite" (91) or "probable" (66) were individually matched by year of birth with miners who had no evidence of rheumatoid arthritis. Unmatched analysis of the case-control status for "probable" and "definite" cases yielded an odds ratio of 2.84 (p = 0.0001). Separate analyses yielded an odds ratio of 3.79 (p = 0.0006) for "definite" cases, a non-significant odds ratio for "probable" cases, and an odds ratio of 5.00 (p = 0.0003) for the presence of rheumatoid factor. These results could not be explained on the basis of cumulative dust exposure or intensity of exposure. The rate of progression of silicosis in both the "definite" and the "probable" groups was greater than for the control patients with silicosis, as was the probability of silicosis presenting at the start with larger nodules (type r).