The Burden of Silicosis in Michigan: 1988-2016

Role of TRIM59 in regulating PPM1A in the pathogenesis of silicosis and the intervention effect of tanshinone IIA

This study examines the involvement of TRIM59 in silica-induced pulmonary fibrosis and explores the therapeutic efficacy of Tanshinone IIA (Tan IIA). In vivo experiments conducted on rats with silica-induced pulmonary fibrosis unveiled an increase in TRIM59 levels and a decrease in PPM1A levels. Subsequent investigations using in vitro silicosis cell models demonstrated that modulation of TRIM59 expression significantly impacts silicosis fibrosis, influencing the levels of PPM1A and activation of the Smad2/3 signaling pathway. Immunofluorescence and co-immunoprecipitation assays confirmed the interaction between TRIM59 and PPM1A in fibroblasts, wherein TRIM59 facilitated the degradation of PPM1A protein via proteasomal and ubiquitin-mediated pathways. Furthermore, employing a rat model of silica-induced pulmonary fibrosis, Tan IIA exhibited efficacy in mitigating lung tissue damage and fibrosis. Immunohistochemical analysis validated the upregulation of TRIM59 and downregulation of PPM1A in silica-induced pulmonary fibrosis, which Tan IIA alleviated. In vitro studies elucidated the mechanism by which Tan IIA regulates the Smad2/3 signaling pathway through TRIM59-mediated modulation of PPM1A. Treatment with Tan IIA in silica-induced fibrosis cell models resulted in concentration-dependent reductions in fibrotic markers and attenuation of relevant protein expressions. Tan IIA intervention in silica-induced fibrosis cell models mitigated the TRIM59-induced upregulation of fibrotic markers and enhanced PPM1A expression, thereby partially reversing Smad2/3 activation. Overall, the findings indicate that while overexpression of TRIM59 may activate the Smads pathway by suppressing PPM1A expression, treatment with Tan IIA holds promise in counteracting these effects by inhibiting TRIM59 expression.

Survival and disease burden analyses of occupational pneumoconiosis during 1958-2021 in Huangshi city, China: a retrospective cohort study

BACKGROUND

Pneumoconiosis, a chronic disease stemming from prolonged inhalation of dust particles, stands as a significant global burden of occupational diseases. This study aims to investigate the survival outcomes of pneumoconiosis patients in Huangshi city, China, while also evaluating the disease burden on afflicted patients.

METHODS

Data for this study were sourced from the Huangshi Center for Disease Control and Prevention. Survival analyses of pneumoconiosis patients were conducted employing life tables and the Kaplan-Meier method. The Cox proportional hazards models were deployed to identify factors influencing pneumoconiosis patients' survival duration. Competing risks models were employed to confirm the validity of the model outcomes. Additionally, in the disease burden assessment, disability-adjusted life years (DALYs) were computed for various demographic groups and time frames.

RESULTS

A total of 5,641 pneumoconiosis cases, diagnosed in Huangshi City, Hubei Province between 1958 and 2021, were incorporated into the cohort analysis. The probability of mortality and the risk ratio increased with advancing age. Notably, the median survival time of stage III pneumoconiosis patients was significantly shorter compared with those in stages I and II. The Cox proportional hazards model and competing risks analyses underscored several significant factors influencing survival time, including dust exposure duration (HR = 1.197, 95% CI: 1.104-1.298), age at first diagnosis (HR = 3.149, 95% CI: 2.961-3.349), presence of silicosis (HR = 1.378, 95% CI: 1.254-1.515), and stage II-III pneumoconiosis (HR = 1.456, 95% CI: 1.148-1.848). Cumulatively, DALYs amounted to 7,974.35 person-years, with an average of 1.41 person-years. The period between 2000 and 2019 witnessed the highest disease burden.

CONCLUSION

Our findings highlight the urgent need for improved prevention, earlier detection, and more effective management strategies for the occupational pneumoconiosis population. This study not only underscores the persistent issue of pneumoconiosis in industrial environments but also serves as a crucial call to action for policymakers and healthcare providers.

Association of smoking cessation with airflow obstruction in workers with silicosis: A cohort study

BACKGROUND

Studies in general population reported a positive association between tobacco smoking and airflow obstruction (AFO), a hallmark of chronic obstructive pulmonary disease (COPD). However, this attempt was less addressed in silica dust-exposed workers.

METHODS

This retrospective cohort study consisted of 4481 silicotic workers attending the Pneumoconiosis Clinic during 1981-2019. The lifelong work history and smoking habits of these workers were extracted from medical records. Spirometry was carried out at the diagnosis of silicosis (n = 4177) and reperformed after an average of 9.4 years of follow-up (n = 2648). AFO was defined as forced expiratory volume in one second (FEV1)/force vital capacity (FVC) less than lower limit of normal (LLN). The association of AFO with smoking status was determined using multivariate logistics regression, and the effect of smoking cessation on the development of AFO was evaluated Cox regression.

RESULTS

Smoking was significantly associated with AFO (current smokers: OR = 1.92, 95% CI 1.51-2.44; former smokers: OR = 2.09, 95% CI 1.65-2.66). The risk of AFO significantly increased in the first 3 years of quitting smoking (OR = 1.23, 95% CI 1.02-1.47) but decreased afterwards with increasing years of cessation. Smoking cessation reduced the risk of developing AFO no matter before or after the confirmation of silicosis (pre-silicosis cessation: HR = 0.58, 95% CI 0.46-0.74; post-silicosis cessation: HR = 0.62, 95% CI 0.48-0.79).

CONCLUSIONS

Smoking cessation significantly reduced the risk of AFO in the workers with silicosis, although the health benefit was not observed until 3 years of abstinence. These findings highlight the importance of early and long-term smoking cessation among silicotic or silica dust-exposed workers.

Analyzing the incidence of silicosis across various industries in Taiwan: a study of occupational disease surveillance by linking national-based workers' and medicoadministrative databases

OBJECTIVES

This study aimed to establish an occupational disease surveillance system by identifying high-risk industries for silicosis in Taiwan using a national database linkage approach.

METHODS

The study was based on a comprehensive analysis of benefit claims from the National Labor Insurance Research Database and medical records from the National Health Insurance Research Database between 2004 and 2020, providing coverage for more than 88.5% of the workforce and 99.9% of citizens. Silicosis was defined as having received compensation for labor insurance benefits or having received a diagnosis of silicosis (International Classification of Diseases, 10th Revision: J62 or International Classification of Diseases, Ninth Revision: 502). The study used the International Standard Industrial Classification of All Economic Activities for industry-specific classification. Cox proportional hazard models were used to compare the silicosis incidence and risk among each industry and identify high-risk industries for silicosis.

RESULTS

This study analyzed 1466 cases of silicosis between 2004 and 2020 and found that 28 industries had incidence rates of over 40 cases per 100,000 workers, indicating more than double the risk of developing silicosis. Of these industries, 14 were considered high risk (relative risk of over four times). Among these, this study identified industries rarely mentioned in the past, such as wholesale of brick, sand, cement, and products, artistic creation, landscape construction, and materials recovery. Stratification by years of work experience reveals those industries such as quarrying of stone, sand, clay, and other mining, construction of buildings, landscape construction, site preparation, foundation and structure construction, building completion and finishing, manufacture of ships, boats, and floating structures, and plumbing, heat, and air conditioning installation display higher hazard ratios for individuals with <10 years of work experience.

CONCLUSIONS

The current surveillance system has identified certain industries that are at a higher risk of developing silicosis, which could be used for future occupational epidemiological surveys and targeted preventive measures in these sectors.

Pneumoconiosis incidence and prevalence among US Medicare beneficiaries, 1999-2019

BACKGROUND

Pneumoconiosis is a group of occupational lung diseases caused by dust and fiber exposure. This study analyzes Medicare claims to estimate the burden of pneumoconiosis among fee-for-service (FFS; Medicare Parts A and B) Medicare beneficiaries during 1999-2019 in the United States.

METHODS

Claim and enrollment information from 81 million continuously enrolled FFS Medicare beneficiaries were analyzed. Beneficiaries with any pneumoconiosis and cause-specific pneumoconiosis (e.g., asbestosis, silicosis) were identified using three case definitions (broad, intermediate, and narrow) with varying diagnostic criteria based on claim International Classification of Diseases, Clinical Modification (ICD-CM) diagnosis codes and Healthcare Common Procedure Coding System codes. Results are presented as ranges of values for the three case definitions.

RESULTS

The 21-year prevalence range for any pneumoconiosis was 345,383-677,361 (412-833 per 100,000 beneficiaries) using the three case definitions. The highest prevalence was among those ≥75 years of age, males, Whites, and North American Natives. Most claims (70.0%-72.5%) included an ICD-CM diagnosis code for asbestosis. The broad pneumoconiosis prevalence rate increased significantly (p < 0.001) during 2002-2009 by 3%-10% annually and declined significantly by 3%-5% annually starting in 2009. The average annual broad incidence rate declined significantly by 7% annually during 2009-2019.

CONCLUSIONS

Despite the decline in rate for any pneumoconiosis among Medicare beneficiaries, which is primarily attributed to a decline in asbestosis, pneumoconiosis is prevalent among FFS Medicare beneficiaries.

Animal models of silicosis: fishing for new therapeutic targets and treatments

Silicosis as an occupational lung disease has been present in our lives for centuries. Research studies have already developed and implemented many animal models to study the pathogenesis and molecular basis of the disease and enabled the search for treatments. As all experimental animal models used to date have their advantages and disadvantages, there is a continuous search for a better model, which will not only accelerate basic research, but also contribute to clinical aspects and drug development. We review here, for the first time, the main animal models developed to date to study silicosis and the unique advantages of the zebrafish model that make it an optimal complement to other models. Among the main advantages of zebrafish for modelling human diseases are its ease of husbandry, low maintenance cost, external fertilisation and development, its transparency from early life, and its amenability to chemical and genetic screening. We discuss the use of zebrafish as a model of silicosis, its similarities to other animal models and the characteristics of patients at molecular and clinical levels, and show the current state of the art of inflammatory and fibrotic zebrafish models that could be used in silicosis research.

Silicosis, asbestosis, and pulmonary fibrosis in Ontario, Canada from 1996 to 2019

BACKGROUND

Silicosis is a fibrotic lung disease caused by exposure to respirable crystalline silica. Historically, silicosis was common among miners and other professions in the 20th century, and in recent decades has re-emerged in coal mining and appeared in new workplaces, including the manufacture of distressed jeans and artificial stone countertops.

METHODS

Physician billing data for the province of Ontario between 1992 and 2019 were analyzed across six time-periods (1993-1995, 1996-2000, 2001-2005, 2006-2010, 2011-2015, and 2016-2019). The case definition was two or more billing records within 24 months with a silicosis diagnosis code (ICD-9 502, ICD-10 J62). Cases from 1993 to 1995 were excluded as prevalent cases. Crude incidence rates per 100,000 persons were calculated by time-period, age, sex, and region. Analyses were repeated in parallel for pulmonary fibrosis (PF) (ICD-9 515, ICD-10 J84) and asbestosis (ICD-9 501; ICD-10 J61).

RESULTS

From 1996 to 2019, 444 cases of silicosis, 2719 cases of asbestosis and 59,228 cases of PF were identified. Silicosis rates decreased from 0.42 cases per 100,000 in 1996-2000 to 0.06 per 100,000 people in 2016-2019. A similar trend was observed for asbestosis (1.66 to 0.51 per 100,000 persons) but the incidence rate of PF increased from 11.6 to 33.9 per 100,000 persons. Incidence rates for all outcomes were higher among men and older adults.

CONCLUSIONS

A decreasing incidence of silicosis was observed in this analysis. However, the incidence of PF increased, consistent with findings from other jurisdictions. While cases of silicosis have been recorded among artificial stone workers in Ontario these cases do not seem to have impacted the population rates thus far. Ongoing, periodic surveillance of occupational diseases is helpful for tracking population-level trends over time.

Exploratory study on noninvasive biomarker of silicosis in exhaled breath by solid-phase microextraction-gas chromatography-mass spectrometry analysis

BACKGROUND

As a chronic occupational disease, silicosis could cause irreversible and incurable impair to the lung. The current diagnosis of silicosis relies on imaging of X-ray or CT, but these methods cannot detect lung lesions in the early stage of silicosis.

OBJECTIVE

To establish a regular screening and early diagnosis methods for silicosis, which could be helpful for the prevention and treatment of silicosis.

METHODS

A total of 161 subjects were enrolled in the study, including 69 patients with silicosis (SILs) and 92 healthy controls. The exhaled breath samples of the subjects were collected with breath sampler and Tedlar bag. The analysis of volatile organic compounds (VOCs) in exhaled breath was performed by solid-phase microextraction (SPME) combined with gas chromatography mass spectrometry (GC-MS).

RESULTS

After excluding the pollutants from sampling bags and instruments, 86 VOCs have been identified in the exhaled breath. The orthogonal partial least squares-discriminant analysis (OPLS-DA) was employed for the screening of potential biomarkers of silicosis. Those components that related to smoking were also excluded from the biomarkers. Finally, nine possible biomarkers for silicosis were screened out, including 2,3-butanedione, ethyl acetate, chlorobenzene, o-cymene, 4-ethylhex-2-ynal, 3,5-dimethyl-3-heptanol, hydroquinone, phthalic anhydride and 5-(2-methylpropyl)nonane. Based on these biomarkers screened, a predicted model for silicosis was generated with the accuracy of 89.61%.

CONCLUSION

The nine biomarkers in exhaled breath were preliminarily screened out for the early diagnosis of silicosis, which can be helpful to the establishment of a noninvasive screening method for silicosis. Follow-up studies should be conducted to further verify these markers.

MALAT1-miR-30c-5p-CTGF/ATG5 axis regulates silica-induced experimental silicosis by mediating EMT in alveolar epithelial cells

Epithelial-mesenchymal transdifferentiation of alveolar type Ⅱ epithelial cells is a vital source of pulmonary myofibroblasts, and myofibroblasts formation is recognized as an important phase in the pathological process of silicosis. miR-30c-5p has been determined to be relevant in the activation of the epithelial-mesenchymal transition (EMT) in numerous disease processes. However, elucidating the role played by miR-30c-5p in the silicosis-associated EMT process remains a great challenge. In this work, based on the establishment of mouse silicosis and A549 cells EMT models, miR-30c-5p was interfered with in vivo and in vitro models to reveal its effects on EMT and autophagy. Moreover, metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), connective tissue growth factor (CTGF), autophagy-related gene 5 (ATG5), and autophagy were further interfered with in the A549 cells models to uncover the possible molecular mechanism through which miR-30c-5p inhibits silicosis associated EMT. The results demonstrated the targeted binding of miR-30c-5p to CTGF, ATG5, and MALAT1, and showed that miR-30c-5p could prevent EMT in lung epithelial cells by acting on CTGF and ATG5-associated autophagy, thereby inhibiting the silicosis fibrosis process. Furthermore, we also found that lncRNA MALAT1 might competitively absorb miR-30c-5p and affect the EMT of lung epithelial cells. In a word, interfering with miR-30c-5p and its related molecules (MALAT1, CTGF, and ATG5-associated autophagy) may provide a reference point for the application of silicosis intervention-related targets.

Progressive massive fibrosis: An overview of the recent literature

This review provides an overview of literature addressing progressive massive fibrosis (PMF) from September 2009 to the present. Advances are described in understanding its pathophysiology, epidemiology of the occurrence of PMF and related conditions, the impact of PMF on pulmonary function, advances in imaging of PMF, and factors affecting progression of pneumoconiosis in dust-exposed workers to PMF. Basic advances in understanding the etiology of PMF are impeded by the lack of a well-accepted animal model for human PMF. Recent studies evaluating lung tissue samples and epidemiologic investigations support an important role for the silica component of coal mine dust in causing coal workers' pneumoconiosis and PMF in contemporary coal miners in the United States and for silica in causing silicosis and PMF in artificial stone workers throughout the world. Development of PMF is associated with substantial decline in pulmonary function relative to no disease or small opacity pneumoconiosis. In recent reports, computed tomography has had greater sensitivity for detecting PMF than chest x-ray. Magnetic resonance imaging shows promise in differentiating between PMF and lung cancer. Although PMF develops in dust-exposed workers without previously identified small opacity pneumoconiosis, the presence of small opacity pneumoconiosis increases the risk for progression to PMF, as does heavier dust exposure. Recent literature does not document any effective new treatments for PMF and new therapies to prevent and treat PMF are an important need.

Epidemiological characteristics and survival analysis on patients with occupational pneumoconiosis in Zhejiang Province from 1987 to 2019

Objective

To evaluate risk factors affecting survival in patients diagnosed with pneumoconiosis and propose strategies to improve the quality of life in these patients.

Methods

The basic patient information was obtained from the pneumoconiosis report card. Disease types, regions, and industry distribution of pneumoconiosis were analyzed. The Kaplan-Meier survival curves and the Cox proportional risk regression model was used for survival analysis.

Results

A total of 13,812 patients were diagnosed with pneumoconiosis in Zhejiang province from 1987 to 2019. The overall survival rate at the end of life table analysis was 83%. Kaplan-Meier analyses showed that there were significant differences between survival curves depending on the stage of first diagnosis, age at first diagnosis, type of pneumoconiosis, industry, and duration of dust exposure (P < 0.05). The results of Cox proportional hazards regression analysis showed that pneumoconiosis stage of first diagnosis, age at first diagnosis, industry, and duration of dust exposure were risk factors affecting patient survival (P < 0.05).

Conclusions

The patients with high stage of pneumoconiosis at first diagnosis, older age, and long duration of dust exposure should be followed up and monitored as key population, and the industries with high incidence of pneumoconiosis such as mining and construction should be supervised as key industries.

Demographic, exposure and clinical characteristics in a multinational registry of engineered stone workers with silicosis

OBJECTIVES

To investigate differences in workplace exposure, demographic and clinical findings in engineered stone (ES) workers from a multinational consortium using the Engineered Stone Silicosis Investigators (ESSI) Global Silicosis Registry.

METHODS

With ethics board approval in Israel, Spain, Australia and the USA, ES workers ages 18+ with a physician diagnosis of work-related silicosis were enrolled. Demographic, occupational, radiologic, pulmonary function and silica-related comorbidity data were compared cross-sectionally among countries using analysis of variance, Fisher's exact tests and logistic regression.

RESULTS

Among 169 ES workers with silicosis, most were men, with mean age 51.7 (±11.4) years. Mean work tenure in stone fabrication or masonry was 19.9 (±9.8) years. Different methods of case ascertainment explained some inter-country differences, for example, workers in Queensland, Australia with a state-based surveillance program were likely to be identified earlier and with shorter work tenure. Overall, 32.5% of workers had progressive massive fibrosis, the most severe form of dust-related pneumoconiosis, of whom 18.5% reported ≤10 years of work tenure. Lung function impairment including restriction, reduced diffusion capacity and hypoxaemia was common, as was autoimmunity.

CONCLUSIONS

Findings from a multinational registry represent a unique effort to compare demographic, exposure and clinical information from ES workers with silicosis, and suggest a substantial emerging population of workers worldwide with severe and irreversible silica-associated diseases. This younger worker population is at high risk for disease progression, multiple comorbidities and severe disability. The ESSI registry provides an ongoing framework for investigating epidemiological trends and developing prospective studies for prevention and treatment of these workers.

Secondary prevention of silicosis and silico-tuberculosis by periodic screening of silica dust exposed workers using serum club cell protein 16 as a proxy marker

BACKGROUND AND OBJECTIVES

Silicosis is a neglected and widely prevalent occupational disease in India and several other countries such as China, South Africa, Brazil, etc. It is an irreversible, incurable, and progressive disease with high morbidity and mortality, which is mostly caused by occupational exposure to silica dusts. Silicosis is usually detected at an advanced stage, when effective intervention is not possible. But early detection appears to be a cost-effective way to control it. There is a need for some suitable biomarker, which could detect silicosis at an early stage for further necessary intervention. This study aimed to estimate the lung damage in silicotic subjects and its relationship with serum CC16 as a proxy marker. The ultimate objective was to explore whether CC16 could be used as a screening tool for early detection of silicosis.

METHODOLOGY

Radiographs of 117 workers having radiological evidences of silicosis were evaluated in accordance with International Labour Organisation (ILO) Classification of chest radiographs and were categorized as mild, moderate, and severe lung damage using a lung damage scoring system, made for the purpose of this study. The concentration of CC16 in serum was determined by enzyme-linked immunosorbent assay.

RESULT

It was observed that serum CC16 values were significantly decreased in relation to increasing lung damage. The mean ± standard deviation (SD) serum CC16 value in mild lung damage group was 8.4 ± 0.87 ng/mL as compared to 4.0 ± 2.10 ng/mL in moderate and 0.7 ± 0.21 ng/mL in high lung damage groups. On the other hand, CC16 value of control (healthy) population was found to be 16.3 ± 3.8 ng/mL.

CONCLUSION

Result of the study concluded that serum CC16 might be used as a periodic screening tool for early detection of silicosis and for it's secondary prevention. It may be viewed as a new approach toward control of silicosis, and an appropriate policy may be adopted.

Silicosis, progressive massive fibrosis and silico-tuberculosis among workers with occupational exposure to silica dusts in sandstone mines of Rajasthan state: An urgent need for initiating national silicosis control programme in India

Context:

Silicosis is a progressive, irreversible and incurable respiratory morbidity and often becomes a cause for pre-mature mortality among occupationally silica dust-exposed workers in India and similar countries. It has a dual problem of associated silico-tuberculosis as a co-morbidity. The present study was done to assess the respiratory morbidity caused by silicosis in sandstone mine of Rajasthan, India.

Methods:

The chest X-rays of 529 subjects having history of employment in stone mines with respiratory morbidity were subjected for this study and evaluated in accordance with ILO Classification 2000. The X-rays were classified into various categories of silicosis and progressive massive fibrosis (PMF) in relation to years of work in stone mines.

Results:

Out of 529 chest radiographs evaluated, 275 (52%) showed radiological evidence of silicosis. Of them, 40 (7.5%) subjects showed large opacities suggestive of progressive massive fibrosis. Both silicosis and progressive massive fibrosis were associated with increasing duration of work in stone mines. Sixty-one (12.4%) subjects with silicosis also had associated pulmonary tuberculosis, termed as silico-tuberculosis.

Conclusion:

The present study showed a high prevalence of silicosis, progressive massive fibrosis and silico-tuberculosis among stone mine workers. It appears that that unless silicosis is controlled, elimination of tuberculosis is far from reality in the country. Hence, states and central authorities must work together towards control of both silicosis as well as silico-tuberculosis. Similarly, there is an urgent need of initiation of national silicosis control programme, similar to existing national tuberculosis control programme, considering the huge burden of silicosis in India

Health Disparities in Environmental and Occupational Lung Disease

Pulmonary health disparities disproportionately impact disadvantaged and vulnerable populations. This article focuses on disparities in disease prevalence, morbidity, and mortality for asthma, chronic obstructive pulmonary disease, pneumoconiosis, and lung cancer. Disparities are categorized by race, age, sex, socioeconomic status, and geographic region. Each category highlights differences in risk factors for the development and severity of lung disease. Risk factors include social, behavioral, economic, and biologic determinants of health (occupational/environmental exposures, psychosocial stressors, smoking, health literacy, health care provider bias, and health care access). Many of these risk factors are complex and inter-related; strategies proposed to decrease disparities require multilevel approaches.

Master Clinician and Public Health Practitioner: Selected Occupational and Environmental Pulmonary Cases

Occupational and environmental exposures contribute to the development and progression of most lung diseases, yet their impact is greatly under-recognized in clinical practice. Clinicians caring for patients with respiratory diseases should maintain a high index of suspicion for occupational and environmental contributing factors. Mastering occupational and environmental medicine clinical decision making requires specialized clinical skills. These skills include obtaining an appropriate work and exposure history; making an assessment of the magnitude and relevance of exposures and their contribution to a patient's respiratory disease; utilizing appropriate resources for evaluation and management of exposure-related disease; and considering socioeconomic and public health factors.

Astragaloside IV alleviates silica‑induced pulmonary fibrosis via inactivation of the TGF‑β1/Smad2/3 signaling pathway

The aim of the present study was to investigate the anti-fibrotic effects of astragaloside IV (ASV) in silicosis rats, and to further explore the potential underlying molecular mechanisms. A silica-induced rat model of pulmonary fibrosis was successfully constructed. Hematoxylin and eosin and Masson's trichrome staining were performed to observe the pathological changes in lung tissues. Immunohistochemical analysis was used to assess the expression levels of Collagen I, fibronectin and α-smooth muscle actin (α-SMA). A hemocytometer and Giemsa staining were used to evaluate the cytological characteristics of the bronchoalveolar lavage fluid. ELISA was used to detect the levels of the inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1β and IL-6. Reverse transcription-quantitative PCR and western blotting were performed to detect the mRNA and protein expression levels of genes associated with the transforming growth factor (TGF)-β1/Smad signaling pathway. ASV alleviated silica-induced pulmonary fibrosis, and reduced the expression of collagen I, fibronectin and α-SMA. In addition, the results of the present study suggested that the ASV-mediated anti-pulmonary fibrosis response may involve reduction of inflammation and oxidative stress. More importantly, ASV suppressed silica-induced lung fibroblast fibrosis via the TGF-β1/Smad signaling pathway, thereby inhibiting the progression of silicosis. In conclusion, the present study indicated that ASV may prevent silicosis-induced fibrosis by reducing the expression of Collagen I, fibronectin and α-SMA, and reducing the inflammatory response and oxidative stress, and these effects may be mediated by inhibiting the activation of the TGF-β1/Smad signaling pathway.

Causes of death among Federal Black Lung Benefits Program beneficiaries enrolled in Medicare, 1999-2016

BACKGROUND

Coal miners with totally disabling pneumoconiosis are eligible for benefits through the Federal Black Lung Benefits Program (FBLP). We identify the causes of death among Medicare beneficiaries with a claim for which the FBLP was the primary payer and compare these causes of death to all deceased Medicare beneficiaries to better understand elevated death and disease among miners with occupational respiratory exposures.

METHODS

From 1999 to 2016 Medicare data, we extracted beneficiary and National Death Index data for 28,003 beneficiaries with an FBLP primary payer claim. We summarized the International Classification of Diseases, Clinical Modification 10th revision-coded underlying causes of death and entity-axis multiple causes of death for 22,242 deceased Medicare beneficiaries with an FBLP primary payer Medicare claim and compared their causes of death to the deceased Medicare beneficiary population.

RESULTS

Among deceased FBLP beneficiaries, the three leading underlying causes of death were chronic obstructive pulmonary disease, unspecified (J44.9, 10.1%), atherosclerotic heart disease (I25.1, 9.3%), and coal workers' pneumoconiosis (CWP) (J60, 9.2%). All diseases of the respiratory system combined (J00-J99) were the underlying cause of death for 29.1% of all beneficiaries, with pneumoconioses (J60-J64) as the underlying cause for 11.0% of all beneficiaries.

CONCLUSIONS

Coal miners enrolled in Medicare with an FBLP primary payer claim were more likely to have specific respiratory and cardiovascular diseases listed as a cause of death than deceased Medicare beneficiaries overall, and were also more likely to die from CWP or any pneumoconioses.

Occupational lung diseases in the 21st century: the changing landscape and future challenges

PURPOSE OF REVIEW

Occupational exposures remain an underrecognized and preventable cause of lung disease in high-income countries. The present review highlights the emergence of cleaning-related respiratory disease and the re-emergence of silicosis as examples of trends in occupational lung diseases in the 21st century.

RECENT FINDINGS

Employment trends, such as the shift from large-scale manufacturing to a service economy, the growth of the healthcare sector, and changing consumer products have changed the spectrum of work-related lung diseases. Following decades of progress in reducing traditional hazards such as silica in U.S. workplaces, cases of advanced silicosis have recently re-emerged with the production of engineered stone countertops. With growth in the healthcare and service sectors in the United States, cleaning products have become an important cause of work-related asthma and have recently been associated with an increased risk of chronic obstructive pulmonary disease (COPD) in women. However, these occupational lung diseases largely go unrecognized by practicing clinicians.

SUMMARY

The present article highlights how changes in the economy and work structure can lead to new patterns of inhalational workplace hazards and respiratory disease, including cleaning-related respiratory disease and silicosis. Pulmonary clinicians need to be able to recognize and diagnose these occupational lung diseases, which requires a high index of suspicion and a careful occupational history.

Characterization of Silica Exposure during Manufacturing of Artificial Stone Countertops

Artificial stone is increasing in popularity in construction applications, including commercial and residential countertops. Eco-friendliness, durability, and resistance to staining, make artificial stone attractive to consumers. Health concerns have arisen during manufacturing of artificial stone due to increased incidence of silicosis after relatively short exposure. Three artificial stone samples (A, B, and C) and one natural granite sample were subjected to cutting and grinding in a controlled environment. Gravimetric analysis, X-Ray diffraction, and scanning electron microscopy with energy dispersive spectroscopy were employed to determine crystalline silica concentrations and particle morphology of bulk and respirable particles. Silica content of bulk dust from artificial samples A and B was 91%, sample C was <10%, while granite was 31%. Silica percent in the respirable fraction for samples A and B was 53% and 54%, respectively, while sample C was <5% and granite was 8%. Number concentrations for samples A and B were mainly in the nano-fraction, indicating potential for translocation of silica particles to other organs outside of the lungs. Respirable dust concentrations inside the chamber were well above Occupational Safety and Health Administration standards for all materials, indicating that confined-space exposures require ventilation to lower risks of acute silicosis regardless of the nature of the stone.

The Protective Role of Tanshinone IIA in Silicosis Rat Model via TGF-β1/Smad Signaling Suppression, NOX4 Inhibition and Nrf2/ARE Signaling Activation

Purpose

Silicosis is an occupational disease caused by inhalation of silica and there are no effective drugs to treat this disease. Tanshinone IIA (Tan IIA), a traditional natural component, has been reported to possess anti-inflammatory, antioxidant, and anti-fibrotic properties. The current study’s purpose was to examine Tan IIA’s protective effects against silica-induced pulmonary fibrosis and to explore the underlying mechanisms.

Methods

48 male SD rats were randomly divided into four groups (n=12): i) Control group; ii) Silicosis group; iii) Tan IIA group; iv) Silicosis +Tan IIA group. Two days after modeling, the rats of Tan IIA group and Silicosis +Tan IIA group were given intraperitoneal administration 25 mg/kg/d Tan IIA for 40 days. Then, the four groups of rats were sacrificed and the lung inflammatory responses were measured by ELISA, lung damage and fibrosis were analyzed by hematoxylin and eosin (H&E) staining and Masson staining, the expression levels of collagen I, fibronectin and α-smooth muscle actin (α-SMA) were measured by immunohistochemistry. The markers of oxidative stress were measured by commercial kits, and the activity of the TGF-β1/Smad and NOX4, Nrf2/ARE signaling pathways were measured by RT-PCR and Western blotting.

Results

The silica-induced pulmonary inflammtory responses, structural damage and fibrosis were significantly attenuated by Tan IIA treatment. In addition, treatment with Tan IIA decreased collagen I, fibronectin and α-SMA expression, and inhibited TGF-β1/Smad signaling in the lung tissue. The upregulated levels of oxidative stress markers in silicosis rats were also markedly restored following Tan IIA treatment. Furthermore, treatment with Tan IIA reduced NOX4 expression and enhanced activation of the Nrf2/ARE pathway in the lung tissue of silicosis rats.

Conclusion

These findings suggest that Tan IIA may protect lung from silica damage via the suppression of TGF-β1/Smad signaling, inhibition of NOX4 expression and activation of the Nrf2/ARE pathway.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/kPjjBxXCkyc

Silica-associated lung disease: An old-world exposure in modern industries

Despite silica dust exposure being one of the earliest recognized causes of lung disease, Australia, USA, Israel, Turkey and other countries around the world have recently experienced significant outbreaks of silicosis. These outbreaks have occurred in modern industries such as denim jean production, domestic benchtop fabrication and jewellery polishing, where silica has been introduced without recognition and control of the hazard. Much of our understanding of silica-related lung disease is derived from traditional occupations such as mining, whereby workers may develop slowly progressive chronic silicosis. However, workers in modern industries are developing acute and accelerated silicosis over a short period of time, due to high-intensity silica concentrations, oxidative stress from freshly fractured silica and a rapid pro-inflammatory and pro-fibrotic response. Appropriate methods of screening and diagnosis remain unclear in these workers, and a significant proportion may go on to develop respiratory failure and death. There are no current effective treatments for silicosis. For those with near fatal respiratory failure, lung transplantation remains the only option. Strategies to reduce high-intensity silica dust exposure, enforced screening programmes and the identification of new treatments are urgently required.

Silicosis prevalence and incidence among Medicare beneficiaries

INTRODUCTION

Existing epidemiologic information on silicosis relies on mortality data.

METHODS

We analyzed health insurance claims and enrollment information from 49 923 987 fee-for-service (FFS) Medicare beneficiaries aged ≥65 from 1999 to 2014. Three different definitions were developed to identify silicosis cases and results are presented as ranges of values for the three definitions.

RESULTS

Among FFS beneficiaries, 10 026-19 696 fit the silicosis case definitions (16-year prevalence: 20.1-39.5 per 100 000) with the highest prevalence among North American Natives (87.2-213.6 per 100 000) and those in New Mexico (83.9-203.4 per 100 000). The annual average prevalence had a significant (P < 0.05) 2-5% annual decline from 2005 to 2014. The average annual number of incident cases had a significant 3-16% annual decline from 2007 to 2014.

CONCLUSIONS

Silicosis is a prevalent disease among Medicare beneficiaries aged ≥65, with variation across the country. Morbidity data from health insurance claims can provide a more complete picture of silicosis burden.