Exploration study on serum metabolic profiles of Chinese male patients with artificial stone silicosis, silicosis, and coal worker's pneumoconiosis.

Long-term exposure to inhaled silica dust induces pneumoconiosis, which remains a heavy burden in developing countries. Modern industry provides new resources of occupational SiO2 leading to artificial stone silicosis especially in developed countries. This study aimed to characterize the serum metabolic profile of pneumoconiosis and artificial stone silicosis patients. Our case-control study recruited 46 pairs of pneumoconiosis patients and dust-exposed workers. Nontargeted metabolomics and lipidomics by ultra-high-performance liquid chromatography-tandem mass spectrometry platform were conducted to characterize serum metabolic profile in propensity score-matched (PSM) pilot study. 54 differential metabolites were screened, 24 of which showed good screening efficiency through receiver operating characteristics (ROC) in pilot study and validation study (both AUC > 0.75). 4 of the 24 metabolites can predict pneumoconiosis stages, which are 1,2-dioctanoylthiophosphatidylcholine, phosphatidylcholine(O-18:1/20:1), indole-3-acetamide and l-homoarginine. Kynurenine, N-tetradecanoylsphingosine 1-phosphate, 5-methoxytryptophol and phosphatidylethanolamine(22:6/18:1) displayed the potential as specific biomarkers for artificial stone silicosis. Taken together, our results confirmed that tryptophan metabolism is closely related to pneumoconiosis and may be related to disease progression. Hopefully, our results could supplement the biomarkers of pneumoconiosis and provide evidence for the discovery of artificial stone silicosis-specific biomarkers.

A rapid point of care CC16 kit for screening of occupational silica dust exposed workers for early detection of silicosis/silico-tuberculosis.

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.

Influence of Silica Exposure for Lung Silicosis Rat.

OBJECTIVE: To investigate the influence of silica exposure on the expression of connective tissue growth factor (CTGF), transforming growth factor beta-1 (TGF-ß1), 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-ß1, 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-ß1, 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-ß1, 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-ß1, and PDGF expressions (P < 0.05). A protein-protein interaction analysis showed interactions between TGF-ß1, CTGF, and PDGF. CONCLUSIONS: TGF-ß/CTGF signaling pathway plays an important role in silicosis. Silicon dioxide exposure can induce the expression of CTGF, TGF-ß1, and PDGF.

Serum levels of inflammatory mediators as prognostic biomarker in silica exposed workers.

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-ß1), 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.

Silicon, an important exposure marker in vivo in silicosis research.

PURPOSE: The degree of silicosis exposure is closely related to the progress of silicosis. At present, we use animal and human studies to explore whether silicon can be an important exposure marker in the development of silicosis. METHODS: Rats were randomly divided into 2 groups: (1) controls; and (2) silicosis. Rats in the silicosis group were killed at 4, 8, 12, 16, 24 h, 3, 7, 14, 21, and 28 days. Hematoxylin-eosin (HE) and immunohistochemistry (IHC) were performed to observe the histomorphology of lung tissue. The expression levels of CC16 and SP-D were detected using ELISA kits. In addition, we conducted a population study. Workers who have been selected to work in an iron mine for more than 1 year as research objects. The population was divided into four groups: silicosis exposure group (workers exposed to silica dust for more than 1 year in an iron mine were selected); patients group (silicosis patients); observation group (evidence of disease not meeting formal diagnostic criteria) and control group. Both the levels of trace silicon in the urine and blood of rats and human subjects were measured with ICP-MS. RESULTS: Serum levels of silicon were immediately increased in rats exposed to silicon dust. Similarly, our population study revealed that the silicon level in the silica exposure group and the observing group (exposed but no obvious symptoms) were significantly increased over that of the control group (P < 0.05). In subjects with extended exposure to silica, the serum and urine silicon level in exposed workers appeared to rapidly increase, reaching its peak in 1-5 years, followed by a gradual decline thereafter. Workers exposed to dust for less than 10 years were divided into subgroups by 2-year limit. The levels of serum silicon, urine silicon, TGF-ß1, and TNF-α were significantly higher than that of control group. CONCLUSION: Changes of the serum levels of silicon occurred earlier than the expression of cytokines such as TNF-α, TGF-ß1, CC16, and SP-D. The level of silicon in workers rapidly increased after exposure to silica, and the change occurred before the expression of TGF-ß1 and TNF-α. As a whole, the findings suggest that determining the level of silicon in vivo might be an effective exposure marker in the diagnosis and pathogenesis of silicosis.

Distinct metabolic features in the plasma of patients with silicosis and dust-exposed workers in China: a case-control study.

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.

Decreased Soluble Receptor of Advanced Glycation End Product Levels Correlated with Inflammation in 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-1ß (IL-1ß), interleukin-6 (IL-6), transforming growth factor-ß1 (TGF-ß1), 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-1ß, IL-6, TGF-ß1, 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-1ß, and ox-LDL. There is no correlation between sRAGE and TGF-ß1 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.

Evaluation of oxysterol levels of patients with silicosis by LC-MS/MS method.

Silicosis is one of the prolonged and irreversible occupational diseases. Crystalline silica dust, which has been linked with silicosis, occurs in different industrial areas such as constructions, ceramic, quarry, and pottery. There are significant numbers of newly diagnosed cases every year in Turkey. Patients with silicosis suffer from inflammatory respiratory disorders and silicosis-related complications such as rheumatoid arthritis, systemic sclerosis, and vasculitis. Oxysterols are defined as 27-carbon intermediates or end products of cholesterol. They are also implicated in the etiology of disease states such as atherosclerosis, neurodegenerative, and inflammatory diseases. The aim of the study is to evaluate cholesterol oxidation products in the patients with silicosis and determination of sphingosine-1-phosphate (S1P) levels which is a sphingolipid metabolite. In addition to these parameters, it is aimed to determine the possible lipid peroxidation by different parameters. For this purpose, blood samples and urine were collected from 47 patients and 30 healthy individual with their consents. In order to evaluate oxysterols, 7-ketocholesterol and cholestan 3ß,5α,6ß-triol levels were measured by LC-MS/MS method. The measured levels of 7-KC were 0.101 ± 0.005 µmol/l in patient and 0.050 ± 0.003 µmol/l in control plasma samples. Triol levels were measured as 0.038 ± 0.005 µmol/l in patient group and 0.033 ± 0.004 µmol/l in control group (p < 0.001). In addition, lipid peroxidation products were measured by human-8-isoprostane, human-4-hydroxynonenal (4-HNE), and human malondialdehyde (MDA) ELISA kits. The measured levels of HNE in the patient and control groups were 735.14 ± 288.80 pg/ml and 595.72 ± 108.62 pg/ml in plasma and 606.02 + 118.23 pg/ml and 531.84 + 107.18 pg/ml in urine, respectively (p < 0.05). F2-iP results of patients and controls were 450.0 + 101.40 pg/dl and 386.9 + 112.7 pg/ml for urine and 432.7 ± 188,8 pg/dl and 321.9 ± 69.4 pg/dl for plasma, respectively (p < 0.05). MDA levels of plasma were measured as 44.1 ± 14.6 nmol/ml in the patient and 31.9 ± 10.5 nmol/ml in the control (p < 0.05). Levels of MDA for urine samples were 30.15 + 5.06 nmol/ml and 25.15 + 6.07 nmol/ml in patients and controls, respectively (p < 0.05). S1P levels were decreased in patients compared to control group (49.05 ± 10.87 and 67.57 ± 16.25, p < 0.001). The results not only indicate a correlation between cholesterol oxidation, lipid peroxidation, and silicosis, but also provide better understanding of the role of the lipids in the mechanism of this inflammatory disease.

Inflammatory and oxidative stress biomarkers induced by silica exposure in crystal craftsmen.

BACKGROUND: Identification of biomarkers associated with the diagnosis and prognosis of silicosis would be highly advantageous in the clinical setting. The aim of this study is to evaluate inflammatory and oxidative stress biomarkers in subjects exposed to silica. METHODS: A cross-sectional study of crystal craftsmen currently (n = 34) or formerly (n = 35) exposed and a group of nonexposed subjects (n = 12) was performed. Personal respirable dust samples were collected. Plasma inflammatory mediators (bone morphogenetic protein- BMP2 and chemokines CXCL16, and CCL5), oxidative stress enzymes (thiobarbituric acid reactive substances [TBARs] and superoxide dismutase [SOD]), and nitrite (NO2- ) were analyzed in parallel with nitric oxide in exhaled breath (FeNO). RESULTS: Being currently or formerly exposed to silica was related to increased levels of CXCL16 and TBARs. Currently, exposed subjects showed decreased levels of SOD. Thirty-seven craftsmen with silicosis (26 formerly and 11 currently exposed) showed higher levels of CXCL16, which was positively associated with the radiological severity of silicosis. Compared with the nonexposed, subjects with silicosis had higher levels of TBARs and those with complicated silicosis had lower levels of SOD. In multivariate analysis, higher levels of CXCL16 were associated with exposure status and radiological severity of silicosis. Smoking was not a confounder. FeNO did not distinguish between the exposure status and the presence of silicosis. CONCLUSION: CXCL16 emerged as a potential biomarker that could distinguish both silica exposure and silicosis. TBARs were elevated in exposed individuals. However, their clinical applications demand further investigation in follow-up studies of representative samples.

[The effects of long-term exposure to silica dust on serum CC16 and KL-6 levels].

Objective: To investigate the effects of long-term exposure to silica dust on serum CC16 and KL-6 levels. Methods: The patients with stage I silicosis who were hospitalized in our hospital from April 2016 to April 2017 were treated as silicosis group. The silica dust exposed workers without silicosis who were taken the physical examination in our hospital were taken as a dust-exposed group. The healthy control group comes from in the same period of community physical examination did not touch the dust. The levels of CC16 and KL-6 in serum of all subjects were determined by enzyme-linked immunosorbent assay (ELISA) , and the levels of CC16 and KL-6 in serum were compared in three groups. Results: Compared with the control group, the serum levels of CC16 in the silicosis group (P<0.01) and the dust-exposed group (P<0.01) were significantly lower. Compared with the control group, the level of serum KL-6 in the silicosis group was significantly decreased (P<0.01) compared with the control group, while the level of KL-6 in the serum of the dust-exposed group was significantly increased (P<0.01) . The ROC area of CC16 for diagnosis of silicosis was 0.92 (P<0.01) , with a sensitivity of 81.37%, specificity of 92.63% and Kappa value of 0.74. Conclusion: Long-term exposure to silica dust may lead to a decrease in serum CC16 levels. Reduced serum CC16 levels may be useful in identifying the diagnosis of silicosis.

[Application value of heparin-binding protein in early diagnosis of severe infection in silicosis patients].

Objective: To explore the value of heparin-binding protein (HBP) in early diagnosis of severe infection in silicosis patients. Methods: From January 2017 to June 2018, fifty silicosis patients with severe infection and fity without infection were recruited in the Second Affiliated Hospital of Xuzhou Medical University. In the severe infection group, the time of patients diagnosed with severe infection was set as the reference point for time. Blood samples were selected from the hospital inspection system sample library at the time of 24, 48, and 72 hours prior to the reference point. In the non-infection group, blood samples were selected within 24 hours of admission. The blood samples were tested for the levels of HBP, C-reactive protein (CRP), procalcitonin (PCT), and white blood cell (WBC) count. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve, sensitivity, specificity and Youden index (YI) were used to evaluate the diagnostic efficacy of each indicator. Results: The HBP levels at 72, 48, 24, and 0 hours before the diagnosis in the severe infection group were significantly higher than those in the non-infection group (all of the P values <0.001), and decreased with the prolonged time before diagnosis. The ROC curve showed that the AUC of HBP at 72, 48, 24, and 0 h before the diagnosis in the severe infection group [0.828 (0.750-0.907), 0.966 (0.920-0.998), 0.967 (0.961-0.998), 0.997 (0.994-0.999)] was higher than that of PCT [0.563 (0.450-0.677), 0.687 (0.581-0.794), 0.726 (0.622-0.829), 0.982 (0.973-0.986)] and CRP [0.564 (0.449-0.680), 0.648 (0.535-0.761), 0.705 (0.594-0.817), 0.963 (0.924-0.983)] and WBC [0.492 (0.377-0.607), 0.497 (0.383-0.612), 0.628 (0.519-0.738), 0.700 (0.598-0.802)] at the corresponding time. The sensitivity, specificity and YI of HBP were 88.9%-97.6%, 77.1%-98.4% and 0.66-0.96 at 72, 36, 24 and 0 h before diagnosis, respectively. Conclusion: Heparin-binding protein can be used for early diagnosis of severe infection in silicosis patients.

CD3+, CD4+, and CD8+ Expression in Cells in Peripheral Blood of Silicosis Patients and Intervention Effect of Thymalfasin.

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.

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.

Highly Sensitive Lab on a Chip (LOC) Immunoassay for Early Diagnosis of Respiratory Disease Caused by Respirable Crystalline Silica (RCS).

Respirable crystalline silica (RCS) produced in mining and construction industries can cause life-threatening diseases such as silicosis, lung cancer, and chronic obstructive pulmonary disease (COPD). These diseases could be more effectively treated and prevented if RCS-related biomarkers were identified and measured at an early stage of disease progression, which makes development of a point of care test (POCT) platform extremely desirable for early diagnosis. In this work, a new, highly sensitive lab on a chip (LOC) immunoassay has been designed, developed, and characterized for tumor necrosis factor α (TNF-α), a protein biomarker that causes lung inflammation due to RCS exposure. The designed LOC device is composed of four reservoirs for sample, enzyme conjugated detection antibody, wash buffer, and chemiluminescence substrate in liquid form, along with three spiral reaction chambers for test, positive control, and negative control. All reservoirs and spiral microchannels were connected in series and designed to perform sequential delivery of immunoassay reagents with minimal user intervention. The developed LOC measured TNF-α concentrations as low as 16 pg/mL in plasma from RCS-exposed rats and also had a limit of detection (LOD) of 0.5 pg/mL in spiked artificial serum. In addition, the analysis time was drastically reduced to about 30 min, as opposed to hours in conventional methods. Successful implementation of a highly sensitive, chemiluminescence-based immunoassay on a preloaded LOC with proper quality control, as reported in this work, can pave the way toward developing a new rapid POCT platform for in-field clinical diagnosis.

Neutrophil to lymphocyte ratio and platelet to lymphocyte ratio as haematological indices of inflammatory response in ceramic workers' silicosis.

INTRODUCTION: Occupational exposure to crystalline silica over time may result in silicosis: a fatal, irreversible occupational disease leading to lung function impairment. A complex inflammatory process, excessive accumulation of mesenchymal cells and collagen production are the primary mechanisms underlying silicosis. Neutrophil to lymphocyte ratio (NLR) and the platelet to lymphocyte ratio (PLR) have emerged as representative indices of systemic inflammation. OBJECTIVES: The purpose of the present study was to investigate the relationship between NLR, PLR and silicosis. METHODS: We retrospectively analysed the demographic and laboratory data of ceramic workers who were referred to our Hospital between 2010 and 2018. Five hundred and seventy-three patients with silicosis and 222 ceramic workers without silicosis (controls) were included in the study. RESULTS: The radiographic ILO classification of silicosis patients was as follows: category 1 (71.5%), category 2 (19.2%), category 3 (7.5%). NLR and PLR in categories 2 and 3 were significantly higher when compared with the control group (P < .005). FEV1 , FEV1 %, FVC, FVC % and PEF were significantly lower in all silicosis patients and also in patients with subcategories (all P < .005). NLR showed a poor positive correlation with CRP (r = 0.095, P < .05) and ESR (r = 0.207, P = .000) while PLR only with ESR (r = 0.317, P = .000) in patients with silicosis. NLR and PLR showed negative correlations with FEV1 , FVC and PEF (all P < .005). CONCLUSION: We conclude that NLR and PLR have significant but poor correlations with pulmonary functions and severity of silicosis, especially in late radiographic profusion categories.

Association between Plasma HMGB-1 and Silicosis: A Case-Control Study.

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.

Inflammatory and oxidative stress parameters as potential early biomarkers for silicosis.

Workers involved in mining activities are exposed to crystalline silica, which leads to constant pulmonary inflammatory reactions and severe oxidative damage, resulting in silicosis. In this work, we aimed to evaluate inflammatory and oxidative stress parameters as potential early biomarkers of effect to assess crystalline silica toxicity in workers who had occupational exposure during mining. We enrolled 38 workers exposed to crystalline silica (WECS), 24 individuals with silicosis (IWS), and 30 occupationally unexposed workers (OUW), a total of 92 participants. The WECS were divided into 2 groups, according to the time of exposure: 19 workers with 1-15 years of occupational exposure (WECS I) and 19 workers with >16 years of occupational exposure (WECS II). The inflammatory parameters assessed were L-selectin, ß-2 integrin, and intercellular adhesion molecule-1 (ICAM-1) surface protein expression in lymphocytes and monocytes, complement C3 and C4, high sensitivity C-reactive protein (hsCRP), and adenosine deaminase (ADA) in serum. Plasma levels of malondialdehyde (MDA) and serum levels of vitamin C were determined as biomarkers of oxidative stress. Biochemical and hematological parameters were also investigated. L-selectin surface protein expression was significantly decreased in the WECS II group (p < 0.05), indicating the importance of this immune system component as a potential marker of crystalline-silica-induced toxicity. The MDA levels were significantly increased in the WECS I, WECS II, and IWS groups compared to the OUW group (p < 0.05). Vitamin C levels were decreased, while C3, hsCRP, ADA, and aspartate aminotransferase (AST) levels were increased in the IWS group compared to the OUW group (p < 0.05). Glucose and urea levels were significantly higher in the WECS I, II, and IWS groups compared to the OUW group (p < 0.05). Negative partial association was found between L-selectin and time of exposure (p < 0.001), supporting the relevance of this biomarker evaluation in long-term exposure to crystalline silica. Significant associations were also observed among inflammatory and oxidative stress biomarkers. Therefore, our results demonstrated the relevance of L-selectin as a potential peripheral biomarker for monitoring crystalline silica-induced toxicity in miners after chronic exposure, before silicosis has developed. However, more studies are necessary for better understanding of the use L-selectin as an early biomarker in exposed workers.

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.

circRNA Mediates Silica-Induced Macrophage Activation Via HECTD1/ZC3H12A-Dependent Ubiquitination.

Rationale: Phagocytosis of silicon dioxide (SiO2) 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 SiO2-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) SiO2 concomitantly decreased circHECTD1 levels and increased HECTD1 protein expression; 2) circHECTD1 and HECTD1 were involved in SiO2-induced macrophage activation via ubiquitination; and 3) SiO2-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 SiO2-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.