Diseases caused by silica: mechanisms of injury and disease development

Adverse Outcome Pathways (AOPs) Oriented Approach to Assess In Vitro Hazard of Silica and Lignin Nanomaterials Derived from Biomass Residues

Bio-based nanomaterials (B-NMs), such as silica oxide (SiO2)- and lignin (Lig)- based nanoparticles (NPs) derived from biomass waste, have gained attention in the last few years in the view of promoting the sustainability principles in several applications. However, scarce data are available about their safety. Thus, a hazard-testing strategy was designed considering as a reference the safe-and-sustainable-by-design (SSbD) framework for chemicals and materials, prioritizing the use of new approach methodologies (NAMs), such as in vitro and adverse outcome pathways (AOPs) approaches, for generating data about the potential hazard of B-NMs. Literature research was performed to identify the adverse outcomes (AOs) related to the selected B-NMs. All the AOPs investigated shared at least oxidative stress, inflammation and cytotoxicity as key events (KEs) that were investigated in lung and immune cells. The tested B-NMs resulted either non-toxic or moderately toxic towards human cells, validating their biocompatibility when compared to reference NMs of similar composition, but not of bio-origin. However, attention should be given to possible AOs deriving after specific functionalization of the B-NMs. Considering the lack of knowledge in this field, the studies performed represent a step forward in the state of the art of the safety assessment of B-NMs.

A mechanistic review-regulation of silica-induced pulmonary inflammation by IL-10 and exacerbation by Type I IFN

Occupational exposure to crystalline silica (CS) is known to induce silicosis, a chronic lung disease characterized by the formation of granulomas and severe lung fibrosis. Specifically, individuals exposed to low doses of CS may develop silicosis after a decade or more of exposure. Similarly, in rat silicosis models exposed to occupationally relevant doses of α-quartz, there is an initial phase characterized by minimal and well-controlled pulmonary inflammation, followed by the development of robust and persistent inflammation. During the initial phase, the inflammation provoked by α-quartz is subdued by two mechanisms. Firstly, α-quartz particles are engulfed by alveolar macrophages (AMs) of the alternatively activated (M2) subtype and interstitial macrophages (IMs), limiting their interaction with other lung cells. Secondly, the anti-inflammatory cytokine, interleukin (IL)-10, is constitutively expressed by these macrophages, further dampening the inflammatory response. In the later inflammatory phase, IL-10-dependent anti-inflammatory state is disrupted by Type I interferons (IFNs), leading to the production of pro-inflammatory cytokines in response to α-quartz, aided by lipopolysaccharides (LPS). This review delves into the complex pathways involving IL-10, LPS, and Type I IFNs in α-quartz-induced pulmonary inflammation, offering a detailed analysis of the underlying mechanisms and identifying areas for future research.

Current Challenges to Align Inflammatory Key Events in Animals and Lung Cell Models In Vitro

With numerous novel and innovative in vitro models emerging every year to reduce or replace animal testing, there is an urgent need to align the design, harmonization, and validation of such systems using in vitro-in vivo extrapolation (IVIVE) approaches. In particular, in inhalation toxicology, there is a lack of predictive and prevalidated in vitro lung models that can be considered a valid alternative for animal testing. The predictive power of such models can be enhanced by applying the Adverse Outcome Pathways (AOP) framework, which casually links key events (KE) relevant to IVIVE. However, one of the difficulties identified is that the endpoint analysis and readouts of specific assays in in vitro and animal models for specific toxicants are currently not harmonized, making the alignment challenging. We summarize the current state of the art in endpoint analysis in the two systems, focusing on inflammatory-induced effects and providing guidance for future research directions to improve the alignment.

Prevalence of pulmonary tuberculosis among casual labourers working in selected road construction sites in central Uganda

INTRODUCTION

Workers with occupational exposure to respirable silica dust, such as casual labourers at road construction sites (RCSs), are known to be at high risk of developing pulmonary tuberculosis (TB). There is limited literature about the burden of PTB among this subpopulation with high occupational exposure to silica dust at road construction sites. We aimed to determine the prevalence of PTB among casual labourers working at road construction sites in central Uganda.

METHODS

We enrolled 297 participants via consecutive sampling in a cross-sectional study between September 1st and September 30th, 2022, at four road construction sites in four districts in central Uganda. A structured questionnaire was administered, and the PTB patients were identified by using GeneXpert and/or computer-aided detection for TB (CAD4TB). The data were analysed with STATA version 17.0. Descriptive statistics adjusted for clustering were used to summarize the data, and the relationships between PTB and independent variables were assessed by using a mixed effects modified Poisson regression model to estimate the adjusted prevalence ratios.

RESULTS

Most participants were males (95.6% [284/297]), and the median age was 29 years (interquartile range [IQR]: 25-33). The prevalence of PTB among casual labourers was 2.4% (95% CI: 1.9, 2.8). Not being vaccinated with BCG (3.45, 95% CI: 1.02, 11.61), alcohol use (2.70, 95% CI: 1.52, 4.80) and staying in shared rooms (8.13, 95% CI: 4.37, 15.12) were positively associated with having PTB.

CONCLUSION

There is a high prevalence of PTB among casual labourers working at road construction sites in central Uganda. Individuals who had never been vaccinated with BCG, alcohol users and those staying in shared rooms were at an increased risk of having PTB. We recommend routine screening of casual labourers at road construction sites to optimize active TB case finding.

Enterosorbents in complex therapy of food allergies: a focus on digestive disorders and systemic toxicity in children

The review analyzes mechanisms and concomitant factors in developing IgE-associated allergic diseases provoked by food allergens and discusses clinical symptoms and current approaches for the treatment of food allergies. The expediency of using enterosorbents in complex therapy of food allergies and skin and respiratory manifestations associated with gastroenterological disorders is substantiated. The review summarizes the experience of using enterosorbents in post-Soviet countries to detoxify the human body. In this regard, special attention is paid to the enterosorbent White Coal (Carbowhite) based on silicon dioxide produced by the Ukrainian company OmniFarma.

Cold-induced adaptive thermogenesis is impaired by exposure of Asian sand dust in mice

Desertification and desert sandstorms caused by the worsening global warming pose increasing risks to human health. In particular, Asian sand dust (ASD) exposure has been related to an increase in mortality and hospital admissions for respiratory diseases. In this study, we investigated the effects of ASD on metabolic tissues in comparison to diesel particulate matter (DPM) that is known to cause adverse health effects. We found that larger lipid droplets were accumulated in the brown adipose tissues (BAT) of ASD-administered but not DPM-administered mice. Thermogenic gene expression was decreased in these mice as well. When ASD-administered mice were exposed to the cold, they failed to maintain their body temperature, suggesting that the ASD administration had led to impairments in cold-induced adaptive thermogenesis. However, impaired thermogenesis was not observed in DPM-administered mice. Furthermore, mice fed a high-fat diet that were chronically administered ASD demonstrated unexplained weight loss, indicating that chronic administration of ASD could be lethal in obese mice. We further identified that ASD-induced lung inflammation was not exacerbated in uncoupling protein 1 knockout mice, whose thermogenic capacity is impaired. Collectively, ASD exposure can impair cold-induced adaptive thermogenic responses in mice and increase the risk of mortality in obese mice.

Interplay of Oxidative Stress, Inflammation, and Autophagy in RAW 264.7 Murine Macrophage Cell Line Challenged with Si/SiO2 Quantum Dots

Quantum dots (QDs) with photostable fluorescence are recommended for imaging applications; however, their effect on living cells is incompletely understood. We aimed to elucidate the RAW 264.7 murine macrophage cell line's response to the Si/SiO₂ QDs challenge. Cells were exposed to 5 and 15 μg/mL Si/SiO₂ QDs for 6 h, 12 h, and 24 h. Cell metabolic activity and viability were assessed by MTT, live/dead, and dye-exclusion assays. Oxidative stress and membrane integrity were assessed by anion superoxide, malondialdehyde, and lactate dehydrogenase activity evaluations. Antioxidative enzyme activities were analyzed by kinetic spectrophotometric methods. Cytokines were analyzed with an antibody-based magnetic bead assay, PGE2 was assessed by ELISA, and Nrf-2, Bcl-2, Beclin 1, and the HSPs were analyzed by western blot. Autophagy levels were highlighted by fluorescence microscopy. The average IC50 dose for 6, 12, and 24 h was 16.1 ± 0.7 μg/mL. Although glutathione S-transferase and catalase were still upregulated after 24 h, superoxide dismutase was inhibited, which together allowed the gradual increase of malondialdehyde, anion superoxide, nitric oxide, and the loss of membrane integrity. G-CSF, IL-6, TNF-α, MIP-1β, MCP-1, Nrf-2, PGE2, and RANTES levels, as well as autophagy processes, were increased at all time intervals, as opposed to caspase 1 activity, COX-2, HSP60, and HSP70, which were only upregulated at the 6-h exposure interval. These results underscore that Si/SiO₂ QDs possess significant immunotoxic effects on the RAW 264.7 macrophage cell line and stress the importance of developing effective strategies to mitigate their adverse impact.

Anomalous Enrichment of As and Hg in Underground Coal Dust: A Case from Xishan Coalfield, Shanxi Province, North China

Coal dust is an important source of coal workers' pneumoconiosis, which is harmful to the health of underground workers. The coal dust samples were directly collected using a coal dust sampler from four major production positions in the underground coal mine. The particle size distribution, mineralogy, and occurrence of As and Hg in the coal dust samples were investigated. The results indicated that the contents of As and Hg were depleted or normal in the parent coal samples compared with the average values of C-P coal in North China and Chinese coal, but they were anomalously enriched in coal dusts. The concentrations of As and Hg in the coal dust samples studied are greater than the values of the elements in the parent coal. The As content in the coal dust samples studied is about one to three orders of magnitude above the parent coal value and the Hg content in the studied coal is 1.28 to 20.28 times higher than the parent coal value. The modes of occurrences of As and Hg were studied by sequential chemical extraction in combination with field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS) and high-resolution transmission electron microscopy-EDS (HRTEM-EDS). The occurrence of As is dominated mainly by pyrite and secondarily by carbonate and silicate in the coal dust samples. Pyritic Hg and organic Hg may be the dominant forms in mining face and heading face samples, and carbonate and pyritic Hg are the main forms in rocks roadway and return airway samples. It is considered that the mechanochemical effect resulted in the formation of surface active sites and modification of the morphology. Harmful trace elements, such as As, Cd, Hg, Se, Pb, Co, Sb, and Tl, and minor grains associated with nanominerals that bear much hazardous elements, could easily be originally fractionated or adsorbed by airborne particulates. This research aims to provide a theoretical basis for the prevention of occupational disease and underground environmental evaluation.

The Effects of Resveratrol on Silica-Induced Lung Oxidative Stress and Inflammation in Rat

BACKGROUND

Chronic exposure to silica is related with the provocation of an inflammatory response and oxidative stress mechanism. Vitamin D has multiple benefits in biological activities particularly respiratory system disease.

METHOD

In this research, 20 male Wistar rats were randomly allocated into four groups (5 rats /group) as follow: Group1 received saline as (negative control) group. The group 2 received a single IT instillation of silica (positive control) group; the group 3 was co-administrated with single IT silica and Vitamin D (20 mg/kg/day) daily for a period of 90 days. The rats of group 4 received Vitamin D daily for a period of 90 days.

RESULTS

Silica significantly increased serum and lung total Oxidant Status (TOS). Meanwhile, silica reduced serum and lung total antioxidant capacity (TAC), GSH and tumor necrosis factor-α (TNF-a). Vitamin D treatment meaningfully reversed oxidative stress, antioxidants status and inflammatory response. Also, Vitamin D improved histopathological changes caused by silica.

CONCLUSION

These findings indicate that Vitamin D exerts protective effects against silica-induced lung injury. It seems that Vitamin D has potential use as a therapeutic object for silica induced lung injure.

Pathogenic Potential of Respirable Spodumene Cleavage Fragments following Application of Regulatory Counting Criteria for Asbestiform Fibres

Health risks from exposure to lithium-bearing spodumene cleavage fragments are unknown. While asbestiform fibres can lead to fibrosis, mesothelioma and lung cancer, controversy remains whether non-asbestiform cleavage fragments, having equivalent dimensions, elicit similar pathologic responses. The mineralogy of respirable particles from two alpha (α)-spodumene concentrate grades (chemical and technical) were characterised using semi-quantitative X-ray diffraction (XRD). Particles were measured using scanning electron microscopy (SEM) and the dimensions (length [L], diameter [D], aspect ratio [AR]) applied to regulatory counting criteria for asbestiform fibres. Application of the current World Health Organization (WHO) and National Occupational Health and Safety Commission (NOHSC) counting criteria, L ˃ 5 µm, D ˂ 3 µm, AR ˃ 3:1, to 10 SEM images of each grade identified 47 countable particles in the chemical and 37 in the technical concentrate test samples. Of these particles, 17 and 16 in the chemical and technical test samples, respectively, satisfied the more rigorous, previously used Mines Safety and Inspection Regulations 1995 (Western Australia [WA]) criteria, L ˃ 5 µm and D ≤ 1 µm. The majority of the countable particles were consistent with α-spodumene cleavage fragments. These results suggest elongated α-spodumene particles may pose a health risk. It is recommended the precautionary principle be applied to respirable α-spodumene particles and the identification and control of dust hazards in spodumene extraction, handling and processing industries be implemented.

Influence of Heat Treatment of Electrospun Carbon Nanofibers on Biological Response

The main aim of this study is to investigate the effect of fragmentation of electrospun carbon nanofibers (eCNFs) obtained at different temperatures, i.e., at 750 °C, 1000 °C, 1500 °C, 1750 °C and 2000 °C on the cellular response in vitro. In order to assess the influence of nanofibers on biological response, it was necessary to conduct physicochemical, microstructural and structural studies such as SEM, XPS, Raman spectroscopy, HRTEM and surface wettability of the obtained materials. During the in vitro study, all samples made contact with the human chondrocyte CHON-001 cell lines. The key study was to assess the genotoxicity of eCNFs using the comet test after 1 h or 24 h. Special attention was paid to the degree of crystallinity of the nanofibers, the dimensions of the degradation products and the presence of functional groups on their surface. A detailed analysis showed that the key determinant of the genotoxic effect is the surface chemistry. The presence of nitrogen-containing groups as a product of the decomposition of nitrile groups has an influence on the biological response, leading to mutations in the DNA. This effect was observed only for samples carbonized at lower temperatures, i.e., 750 °C and 1000 °C. These results are important with respect to selecting the temperature of thermal treatment of eCNFs dedicated for medical and environmental functions due to the minimization of the genotoxic effect of these materials.

Tetracycline ameliorates silica-induced pulmonary inflammation and fibrosis via inhibition of caspase-1

Background

Inhalation of dust containing silica particles is associated with severe pulmonary inflammation and lung injury leading to chronic silicosis including fibrotic remodeling of the lung. Silicosis represents a major global health problem causing more than 45.000 deaths per year. The inflammasome-caspase-1 pathway contributes to the development of silica-induced inflammation and fibrosis via IL-1β and IL-18 production. Recent studies indicate that tetracycline can be used to treat inflammatory diseases mediated by IL-1β and IL-18. Therefore, we hypothesized that tetracycline reduces silica-induced lung injury and lung fibrosis resulting from chronic silicosis via limiting IL-1β and IL-18 driven inflammation.

Methods

To investigate whether tetracycline is a therapeutic option to block inflammasome-caspase-1 driven inflammation in silicosis, we incubated macrophages with silica alone or combined with tetracycline. The in vivo effect of tetracycline was determined after intratracheal administration of silica into the mouse lung.

Results

Tetracycline selectively blocks IL-1β production and pyroptotic cell death via inhibition of caspase-1 in macrophages exposed to silica particles. Consistent, treatment of silica-instilled mice with tetracycline significantly reduced pulmonary caspase-1 activation as well as IL-1β and IL-18 production, thereby ameliorating pulmonary inflammation and lung injury. Furthermore, prolonged tetracycline administration in a model of chronic silicosis reduced lung damage and fibrotic remodeling.

Conclusions

These findings suggest that tetracycline inhibits caspase-1-dependent production of IL-1β in response to silica in vitro and in vivo. The results were consistent with tetracycline reducing silica-induced pulmonary inflammation and chronic silicosis in terms of lung injury and fibrosis. Thus, tetracycline could be effective in the treatment of patients with silicosis as well as other diseases involving silicotic inflammation.

Genotoxicity Response of Fibroblast Cells and Human Epithelial Adenocarcinoma In Vitro Model Exposed to Bare and Ozone-Treated Silica Microparticles

Indoor air pollutants (IAP), which can pose a serious risk to human health, include biological pollutants, nitric oxide (NO), nitrogen dioxide (NO2), volatile organic compounds (VOC), sulfur dioxide (SO2), carbon monoxide (CO), carbon dioxide (CO2), silica, metals, radon, and particulate matter (PM). The aim of our work is to conduct a multidisciplinary study of fine silica particles (<2.5 μm) in the presence or absence of ozone (O3), and evaluate their potential cytotoxicity using MTS, micronucleus, and the comet test in two cell lines. We analyzed A549 (human basal alveolar epithelial cell adenocarcinoma) and Hs27 (human normal fibroblasts) exposed to dynamic conditions by an IRC simulator under ozone flow (120 ppb) and in the presence of silica particles (40 μg/h). The viability of A549 and Hs27 cells at 48 and 72 h of exposure to silica or silica/ozone decreases, except at 72 h in Hs27 treated with silica/ozone. The micronucleus and comet tests showed a significant increase in the number of micronuclei and the % of DNA in the queue, compared to the control, in both lines in all treatments, even if in different cell times/types. We found that silica alone or with more O3 causes more pronounced genotoxic effects in A549 tumor cells than in normal Hs27 fibroblasts.

Serum apolipoprotein A-I depletion is causative to silica nanoparticles-induced cardiovascular damage

The rapid development of nanotechnology has greatly benefited modern science and engineering and also led to an increased environmental exposure to nanoparticles (NPs). While recent research has established a correlation between the exposure of NPs and cardiovascular diseases, the intrinsic mechanisms of such a connection remain unclear. Inhaled NPs can penetrate the air-blood barrier from the lung to systemic circulation, thereby intruding the cardiovascular system and generating cardiotoxic effects. In this study, on-site cardiovascular damage was observed in mice upon respiratory exposure of silica nanoparticles (SiNPs), and the corresponding mechanism was investigated by focusing on the interaction of SiNPs and their encountered biomacromolecules en route. SiNPs were found to collect a significant amount of apolipoprotein A-I (Apo A-I) from the blood, in particular when the SiNPs were preadsorbed with pulmonary surfactants. While the adsorbed Apo A-I ameliorated the cytotoxic and proinflammatory effects of SiNPs, the protein was eliminated from the blood upon clearance of the NPs. However, supplementation of Apo A-I mimic peptide mitigated the atherosclerotic lesion induced by SiNPs. In addition, we found a further declined plasma Apo A-I level in clinical silicosis patients than coronary heart disease patients, suggesting clearance of SiNPs sequestered Apo A-I to compromise the coronal protein's regular biological functions. Together, this study has provided evidence that the protein corona of SiNPs acquired in the blood depletes Apo A-I, a biomarker for prediction of cardiovascular diseases, which gives rise to unexpected toxic effects of the nanoparticles.

Tuberculosis Screening in Silica-Exposed Workers : Developing a Tool for Health Care Providers

Both the Occupational Safety and Health Administration and Washington State require safety and health protections for workers exposed to respirable crystalline silica, including tuberculosis (TB) screening as part of occupational medical surveillance. We describe the creation of a TB screening tool for silica-exposed workers receiving regulated medical surveillance examinations in Washington State. The tool provides relevant clinical recommendations to assist health care providers and public health practitioners who choose to use the tool when performing such examinations. A cross-disciplinary team at the Washington State Department of Labor and Industries created the TB screening tool to help health care providers identify silica-exposed workers who should receive a comprehensive evaluation for active TB disease and workers who should or must receive testing for latent TB infection. The Washington State Adult Tuberculosis Screening Tool for Workers Exposed to Respirable Crystalline Silica benefits occupational and respiratory clinicians and public health practitioners by aiding both the individual- and population-level delivery of occupational health and TB screening services to silica-exposed workers receiving required medical surveillance examinations.

The Ameliorative Effects of Arctiin and Arctigenin on the Oxidative Injury of Lung Induced by Silica via TLR-4/NLRP3/TGF-β Signaling Pathway

Silicosis remains one of the most serious diseases worldwide, with no effective drug for its treatment. Our research results have indicated that arctiin and arctigenin could increase the mitochondrial membrane potential, which in turn reduces the production of reactive oxygen species (ROS), blocks the polarization of macrophages, and inhibits the differentiation of myofibroblasts to reduce oxidative stress, inflammation, and fibrosis. Further, our study revealed that arctiin and arctigenin suppressed the activation of NLRP3 inflammasome through the TLR-4/Myd88/NF-κB pathway and the silica-induced secretion of TNF-α, IL-1β, TGF-β, and α-SMA. Besides, the silica-induced increase in the levels of serum ceruloplasmin and HYP was also inhibited. Results of metabolomics indicated that arctiin and arctigenin could regulate the abnormal metabolic pathways associated with the development of silicosis, which involve pantothenate and CoA biosynthesis, cysteine and methionine metabolism, linoleic acid metabolism, and arginine and proline metabolism successively. Furthermore, the analysis of metabolomics, together with network topological analysis in different phases of silicosis, revealed that urine myristic acid, serum 4-hydroxyproline, and L-arginine could be regarded as diagnosis biomarkers in the early phase and formation of pulmonary fibrosis in the latter phases of silicosis. Arctiin and arctigenin could downregulate the increased levels of myristic acid in the early phase and serum 4-hydroxyproline in the latter phase of silicosis. Interestingly, the integration of TLR-4/NLRP3/TGF-β signaling and metabolomics verified the importance of macrophage polarization in the silicosis fibrosis process. To the best of our knowledge, this is the first study reporting that arctiin and arctigenin both can ameliorate silicosis effectively, and the former is a little stronger than its aglycone arctigenin because of its high oral bioavailability, low toxicity, and multimolecular active metabolites as determined by AdmetSAR and molecular docking analysis.

Extracellular signal-regulated kinase signaling pathway and silicosis

Silicosis is a scarring lung disease caused by inhaling fine particles of crystalline silica in the workplace of many industries. Due to the lack of effective treatment and management, the continued high incidence of silicosis remains a major public health concern worldwide, especially in the developing countries. Till now, related molecular mechanisms underlying silicosis are still not completely understood. Multiple pathways have been reported to be participated in the pathological process of silicosis, and more complex signaling pathways are receiving attention. The activated extracellular signal-regulated kinase (ERK) signaling pathway has been recognized to control some functions in the cell. Recent studies have identified that the ERK signaling pathway contributes to the formation and development of silicosis through regulating the processes of oxidative stress, inflammatory response, proliferation and activation of fibroblasts, epithelial-mesenchymal transformation, autophagy, and apoptosis of cells. In this review article, we summarize the latest findings on the role of ERK signaling pathway in silica-induced experimental models of silicosis, as well as clinical perspectives.

Krill oil and low-dose aspirin combination mitigates experimentally induced silicosis in rats: role of NF-κB/TGF-β1/MMP-9 pathway

This study is an attempt to assess pulmonary protective and antifibrotic potentials of a combination of aspirin, a widely used anti-inflammatory and cardioprotective agent, and krill oil, a naturally occurring omega-3 fatty acid source, against silica-induced pulmonary injury. For silicosis induction, silica particles (50 mg/rat, 0.1 mL 0.9% NaCl) were instilled intranasally into rats. Aspirin (10 mg/kg/day), krill oil (40 mg/kg/day), or their combination was administered orally for 56 days following silica exposure. Results showed that oral aspirin and krill oil combination significantly mitigated silica-induced pulmonary injury. Bronchoalveolar lavage fluid examination showed a decreased lactate dehydrogenase activity, total protein content, and accumulation of total and differential inflammatory cells. Oral aspirin and krill oil combination significantly attenuated silica-induced oxidative stress through the restoration of reduced glutathione concentration and catalase activity in addition to alleviation of elevated malondialdehyde and total nitric oxide contents. Moreover, aspirin and krill oil combination revealed considerable mitigation of silica-induced upregulated expression of the inflammatory and fibrotic mediators: nuclear factor kappa-B, transforming growth factor-β1, and matrix metalloproteinase-9. The antifibrotic effect was also evidenced through the decreased hydroxyproline content and the obvious restoration of lung architecture, as demonstrated upon histopathological examination. In conclusion, oral aspirin and krill oil combination can confer pulmonary protective, anti-inflammatory, and antifibrotic potentials against silica-induced pulmonary injury. This impact could be credited to the ability of this combination to activate resolution mechanisms, which, in turn, suppress the expression of inflammatory and fibrotic biomarkers and replenish antioxidant stores.

Occupational lung disease: A narrative review of lung conditions from the workplace

Occupational lung diseases are lung conditions caused or made worse by materials when a person is exposed to a workplace. The diagnosis of an occupational disease is important for workers' decision to continue work and for their eligibility under compensation programmes. We revisit the existing lung diseases that are closely associated with the occupation at the workplace namely occupational asthma, silicosis, black lung disease, farmers' lung disease, asbestos-linked disease, and hypersensitivity pneumonitis. Occupational lung diseases contribute toward global health and economic impacts. Prevention and control of occupational lung diseases require a collaborative effort among employers, workers, occupational physicians, pulmonary physicians, industrial hygienists, and members from other disciplines.

Induction of DNA damage as a consequence of occupational exposure to crystalline silica: A review and meta-analysis

About 40 million workers are occupationally exposed to crystalline silica (CS) which was classified as a human carcinogen by the IARC. It is assumed that damage of the genetic material via inflammation and reactive oxygen species by CS lead to formation of malignant cells. We conducted a systematic literature search to find out if inhalation of CS containing dusts at workplaces causes damage of the genetic material. Thirteen studies were found eligible for this review, in most of them (n = 9) micronuclei (MN) which reflect structural/numerical chromosomal aberrations were monitored in lymphocytes and/or in exfoliated buccal cells. In 5 investigations DNA damage was measured in blood cells in single cell gel electrophoresis (comet) experiments. Frequently studied groups were potters, stone cutters, miners and construction workers. Results of meta-analyses show that exposure to CS causes formation of MN and DNA breaks, the overall ratio values were in exposed workers 2.06- and 1.96-fold higher than in controls, respectively. Two studies reported increased levels of oxidized guanine, and higher levels of DNA adducts with malondialdehyde indicating that exposure to CS leads to oxidative damage. The exposure of the workers to CS was quantified only in two studies, information concerning the size and chemical structures of the particles is lacking in most investigations. Therefore, it is not possible to use the results to derive occupational exposure limits of workers to CS which vary strongly in different countries. Nevertheless, the evaluation of the current state of knowledge shows that biomonitoring studies in which damage of the genetic material is measured in CS exposed workers can contribute to assess adverse health effects as consequence of DNA instability in specific occupations.

Silica-related diseases in the modern world

Silicosis is an ancient and potentially fatal pneumoconiosis caused by exposure to respirable crystalline silica. Silicosis is historically a disease of miners; however, failure to recognize and control the risk associated with silica exposure in contemporary work practices such as sandblasting denim jeans and manufacturing of artificial stone benchtops has led to re-emergence of silicosis around the world. This review outlines the mineralogy, epidemiology, clinical and radiological features of the various forms of silicosis and other silica-associated diseases. Perspective is provided on the most recent studies shedding light on pathogenesis, including the central role of innate immune effector cells and subsequent inflammatory cascades in propagating pulmonary fibrosis and the extrapulmonary manifestations, which uniquely characterize this pneumoconiosis. Clinical conundrums in differential diagnosis, particularly between silicosis and sarcoidosis, are highlighted, as is the importance of obtaining a careful occupational history in the patient presenting with pulmonary infiltrates and/or fibrosis. While silicosis is a completely preventable disease, unfortunately workers around the world continue to be affected and experience progressive or even fatal disease. Although no treatments have been proven, opportunities to intervene to prevent progressive disease, founded in a thorough cellular and molecular understanding of the immunopathology of silicosis, are highlighted.

miR-135a Alleviates Silica-Induced Pulmonary Fibrosis by Targeting NF-κB/Inflammatory Signaling Pathway

Silica exposure triggers inflammatory response and pulmonary fibrosis that is a severe occupational or environmental lung disease with no effective therapies. The complicated biological and molecular mechanisms underlying silica-induced lung damages have not yet been fully understood. miR-135a inhibits inflammation, apoptosis, and cancer cell proliferation. But the roles of miRNA135a involved in the silica-induced lung damages remain largely unexplored. We investigated the roles and mechanisms of miR-135a underlying silica-induced pulmonary fibrosis. The present study showed silica exposure caused the decrease in miR-135a level but the increase in inflammatory mediators. Transduction of lentivirus expressing miR-135a reduced the level of inflammatory mediators in lung tissues from silica-treated mice and improved pulmonary fibrosis which was consistent with the downregulated α-SMA but enhanced E-cadherin. Moreover, miR-135a overexpression inhibited p-p65 level in lung tissues. Overexpression of miR-135a inhibitor strengthened TLR4 protein level and NF-κB activation in BEAS-2B cells. Injection of PDTC, an inhibitor of NF-κB, further reinforced miR-135a-mediated amelioration of inflammation and pulmonary fibrosis induced by silica. The collective data indicate miR-135a restrains NF-κB activation probably through targeting TLR4 to alleviate silica-induced inflammatory response and pulmonary fibrosis.

Raman spectroscopy as a potential diagnostic tool to analyse biochemical alterations in lung cancer

Patient survival remains poor even after diagnosis in lung cancer cases, and the molecular events resulting from lung cancer progression remain unclear. Raman spectroscopy could be used to noninvasively and accurately reveal the biochemical properties of biological tissues on the basis of their pathological status. This study aimed at probing biomolecular changes in lung cancer, using Raman spectroscopy as a potential diagnostic tool. Herein, biochemical alterations were evident in the Raman spectra (region of 600-1800 cm^-1) in normal and cancerous lung tissues. The levels of saturated and unsaturated lipids and the protein-to-lipid, nucleic acid-to-lipid, and protein-to-nucleic acid ratios were significantly altered among malignant tissues compared to normal lung tissues. These biochemical alterations in tissues during neoplastic transformation have profound implications in not only the biochemical landscape of lung cancer progression but also cytopathological classification. Based on this spectroscopic approach, classification methods including k-nearest neighbour (kNN) and support vector machine (SVM) were successfully applied to cytopathologically diagnose lung cancer with an accuracy approaching 99%. The present results indicate that Raman spectroscopy is an excellent tool to biochemically interrogate and diagnose lung cancer.

Susceptibility Variations in Air Pollution Health Effects: Incorporating Neuroendocrine Activation

Diverse host factors/phenotypes may exacerbate or diminish biological responses induced by air pollutant exposure. We lack an understanding of biological indicators of environmental exposures that culminate in a physiological response versus those that lead to adversity. Variations in response phenotype might arise centrally and/or at the local tissue level. In addition to genetic differences, the current evidence supports the roles of preexisting cardiopulmonary diseases, diabetes, diet, adverse prenatal environments, neurobehavioral disorders, childhood infections, microbiome, sex, and psychosocial stressors in modifying the susceptibility to air pollutant exposures. Animal models of human diseases, obesity, nutritional inadequacies, and neurobehavioral conditions have been compared with healthy controls to understand the causes of variations in susceptibility. Although psychosocial stressors have been associated with increased susceptibility to air pollutant effects, the contribution of neuroendocrine stress pathways in mediating these effects is just emerging. The new findings of neuroendocrine activation leading to systemic metabolic and immunological effects of air pollutants, and the potential contribution to allostatic load, emphasize the consideration of these mechanisms into susceptibility. Variations in susceptibility to air pollution health effects are likely to underlie host genetic and physiological conditions in concert with disrupted neuroendocrine circuitry that alters physiological stability under the influence of stressors.

The Epidemiology of Breast Implant-Associated Anaplastic Large Cell Lymphoma in Australia and New Zealand Confirms the Highest Risk for Grade 4 Surface Breast Implants

BACKGROUND

The epidemiology and implant-specific risk for breast implant-associated (BIA) anaplastic large cell lymphoma (ALCL) has been previously reported for Australia and New Zealand. The authors now present updated data and risk assessment since their last report.

METHODS

New cases in Australia and New Zealand were identified and analyzed. Updated sales data from three leading breast implant manufacturers (i.e., Mentor, Allergan, and Silimed) were secured to estimate implant-specific risk.

RESULTS

A total of 26 new cases of BIA-ALCL were diagnosed between January of 2017 and April of 2018, increasing the total number of confirmed cases in Australia and New Zealand to 81. This represents a 47 percent increase in the number of reported cases over this period. The mean age and time to development remain unchanged. The implant-specific risk has increased for Silimed polyurethane (23.4 times higher) compared with Biocell, which has remained relatively static (16.5 times higher) compared with Siltex implants.

CONCLUSIONS

The number of confirmed cases of BIA-ALCL in Australia and New Zealand continues to rise. The implant-specific risk has now changed to reflect a strong link to implant surface area/roughness as a major association with this cancer.

A review of the fate of inhaled α-quartz in the lungs of rats

The distribution of dust particles within the lungs and their excretion are highly associated with their pulmonary toxicity. Literature was reviewed to discern pulmonary translocation pathways for inhaled α-quartz compared to those for inhaled TiO₂. Accordingly, it was hypothesized α-quartz particles in the alveoli were phagocytized by alveolar macrophages but silica-containing macrophages remained in the alveoli for longer time in contrast to the rapid elimination from the alveoli seen for TiO₂-containing macrophages. In addition, it was presumed that free silica particles are translocated in the interstitium, possibly through the cytoplasm of Type I epithelial cells, as observed with TiO₂. Free silica particles are presumed to be phagocytized by interstitial macrophages soon after the particles penetrate the interstitium; these dust cells are then translocated to the ciliated airway regions in the lumen through bronchus-associated lymphoid tissue (BALT). The pulmonary retention half-time of dust particles in rats exposed to α-quartz is several times longer than that of rats exposed to TiO₂, as long as the lung dust burden is ≈ 3 mg. The reduced pulmonary particle clearance ability in rats exposed to α-quartz aerosol is presumably attributed to the long-term retention of dust cells both in the alveoli and in the interstitium; this retention may be caused by the reduced chemotactic abilities of α-quartz-containing dust cells. However, the accumulation of α-quartz-containing dust cells in the lungs is not associated with the occurrence of pulmonary inflammation.

Immunity to the Dual Threat of Silica Exposure and Mycobacterium tuberculosis

Exposure to silica and the consequent development of silicosis are well-known health problems in countries with mining and other dust producing industries. Apart from its direct fibrotic effect on lung tissue, chronic and immunomodulatory character of silica causes susceptibility to tuberculosis (TB) leading to a significantly higher TB incidence in silica-exposed populations. The presence of silica particles in the lung and silicosis may facilitate initiation of tuberculous infection and progression to active TB, and exacerbate the course and outcome of TB, including prognosis and survival. However, the exact mechanisms of the involvement of silica in the pathological processes during mycobacterial infection are not yet fully understood. In this review, we focus on the host's immunological response to both silica and Mycobacterium tuberculosis, on agents of innate and adaptive immunity, and particularly on silica-induced immunological modifications in co-exposure that influence disease pathogenesis. We review what is known about the impact of silica and Mycobacterium tuberculosis or their co-exposure on the host's immune system, especially an impact that goes beyond an exclusive focus on macrophages as the first line of the defense. In both silicosis and TB, acquired immunity plays a major role in the restriction and/or elimination of pathogenic agents. Further research is needed to determine the effects of silica in adaptive immunity and in the pathogenesis of TB.

An investigation into respiratory health problems of workers at stone crushing industries in Bangladesh

Purpose

Occupational exposure to dust is a major health and safety concern for workers in developing countries. Such laborers are often exposed to dust without being aware of its threat to their health. In the process of crushing stone, mineralogical materials are released into the environment. The material includes dust, fumes, ashes or other industrial waste which may constitute toxic elements. The purpose of this paper is to investigate the respiratory health problems of stone crushing industry workers in Bangladesh.

Design/methodology/approach

This cross-sectional descriptive research study was conducted by adopting a multi-method approach. Data were collected by use of a questionnaire survey, focus group discussions, in-depth interview and spirometric examinations. Focus group discussions and questionnaire surveys were conducted among 240 workers. The respondents were divided in six groups for the spirometric examination. The questionnaire was formulated by following standards set by the American Thoracic Society Division of Lung Disease questionnaire and European Coal and Steel Community. Data on respondent’s height, weight and smoking habits were collected by using a structured checklist. Meanwhile, lung functions were assessed by spirometry. A Statistical Package for Social Sciences was used to analyze the data.

Findings

The results show that there was a significant relation between respiratory problems and inhalation of dust and particulate matter and cigarette smoking. It also shows that coughing was the most common problem among the respondents. The majority of respondents suffered from obstructive types of respiratory problems.

Originality/value

Findings of the study reveals that chronic exposure to dust at stone crushing plants increases the risk of respiratory problems and the impaired lung function of workers. It also reveals that there is a significant relation between respiratory problems and inhalation of dusts and cigarette smoking. Raising awareness about health risks amongst workers could reduce these health hazards. The government should make a national policy for the prevention, control and elimination of silica exposure and silicosis. The results would help to raise awareness of the issue. Finally, it would raise awareness on respiratory health problems of workers at stone crushing industries in Bangladesh and help the government to make a policy for the prevention, control and elimination of silica exposure and silicosis, and thus enhancing public health policy and practices in the country.

Silica-induced fibrosis: an ancient response from the early metazoans

Exposure to crystalline silica particles causes silicosis, an occupational disease leading to an overproduction of collagen in the lung. The first step of this pathology is characterized by the release of inflammatory mediators. Tumour necrosis factor (TNF) is a pro-inflammatory cytokine directly involved in silica-induced pulmonary fibrosis. The marine demosponge Chondrosia reniformis is able to incorporate silica grains and partially dissolve the crystalline forms apparently without toxic effects. In the present work, C. reniformis tissue explants were treated with fine quartz dust and the expression level of fibrogenic genes was assayed by qPCR, demonstrating an overexpression of a fibrillar and a non-fibrillar collagen and of prolyl-4-hydroxylase enzyme. The deposition of new collagen could also be documented in quartz-treated sponge explants. Furthermore, TNF pro-inflammatory cytokine overexpression and involvement in silica-induced sponge collagen biosynthesis was demonstrated in quartz-treated explants as compared with controls by means of specific TNF inhibitors affecting the fibrogenic gene response. As no documentable detrimental effect was observed in treated explants, we conclude that the C. reniformis unique quartz engulfment and erosion is physiological and beneficial to the animal, leading to new collagen synthesis and strengthening of the body stiffness. Thus, we put forward the hypothesis that an ancient physiological behaviour from the lowest of the Metazoa, persisting through evolution via the same molecular mediators such as TNF, may have become the cause of disease in the specialized tissues of higher animals such as mammals.

Insect Analogue to the Lotus Leaf: A Planthopper Wing Membrane Incorporating a Low-Adhesion, Nonwetting, Superhydrophobic, Bactericidal, and Biocompatible Surface

Nature has produced many intriguing and spectacular surfaces at the micro- and nanoscales. These small surface decorations act for a singular or, in most cases, a range of functions. The minute landscape found on the lotus leaf is one such example, displaying antiwetting behavior and low adhesion with foreign particulate matter. Indeed the lotus leaf has often been considered the "benchmark" for such properties. One could expect that there are animal counterparts of this self-drying and self-cleaning surface system. In this study, we show that the planthopper insect wing (Desudaba danae) exhibits a remarkable architectural similarity to the lotus leaf surface. Not only does the wing demonstrate a topographical likeness, but some surface properties are also expressed, such as nonwetting behavior and low adhering forces with contaminants. In addition, the insect-wing cuticle exhibits an antibacterial property in which Gram-negative bacteria (Porphyromonas gingivalis) are killed over many consecutive waves of attacks over 7 days. In contrast, eukaryote cell associations, upon contact with the insect membrane, lead to a formation of integrated cell sheets (e.g., among human stem cells (SHED-MSC) and human dermal fibroblasts (HDF)). The multifunctional features of the insect membrane provide a potential natural template for man-made applications in which specific control of liquid, solid, and biological contacts is desired and required. Moreover, the planthopper wing cuticle provides a "new" natural surface with which numerous interfacial properties can be explored for a range of comparative studies with both natural and man-made materials.

Effects of Occupational Silica Exposure on OXIDATIVE Stress and Immune System Parameters in Ceramic Workers in TURKEY

Silica is the second most common element after oxygen, and therefore, exposures to crystalline silica dust occur in a large variety of occupations such as metal foundries, constructions, and ceramic, quarry, and pottery industries. Since crystalline silica exposure has been linked with silicosis, lung cancer, and other pulmonary diseases, adverse effect attributed to this element has be a cause for concern worldwide. Silica dust exposure in workers is still considered to be important health problem especially in developing countries. The aim of the study was to investigate the effects of occupational silica exposure on oxidative stress parameters including the activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and levels of total glutathione (GSH) and thiobarbituric acid reactive substance (TBARS) as well as immune system parameters such as interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, and IL-10 and tumor necrosis factor (TNF)-α in Turkish ceramic workers. In this study, nearly 50% of Turkish ceramic workers were diagnosed with silicosis. Eighty-four percent of these silicotic workers were found to present with profusion category 1 silicosis, whereas controls (n = 81) all displayed normal chest radiographs. Data demonstrated a significant decrease in levels of GSH and activities of CAT, SOD, and GPx, but a significant increase in MDA levels and activity of GR in all workers. Further, workers possessed significantly higher levels of IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, and TNF-α. These observations suggest that ceramic workers may have impaired antioxidant/oxidant status and activated immune system indicative of inflammatory responses.

Cytotoxic, genotoxic and mutagenic evaluation of surface waters from a coal exploration region

Coal mining generates a considerable amount of waste, which is disposed of in piles or dams near mining sites. As a result, leachates may reach rivers and streams, promoting the wide dispersion of contaminants in solution and as particulate matter. The present study evaluated the cytotoxic, genotoxic, and mutagenic action of surface waters collected around a thermoelectric power plant and the largest mining area in Brazil (Candiota). Four sites in Candiota stream were selected, and samples were collected in winter and summer. Water samples were analyzed using the comet and CBMN assays in V79 and HepG2 cells. Furthermore, genotoxicity of water samples was evaluated in vivo using the SMART in Drosophila melanogaster. In addition, polycyclic aromatic hydrocarbons and inorganic elements were quantified. The results indicate that water samples exhibited no genotoxic and mutagenic activities, whether in vitro or in vivo. On the other hand, surface water samples collected in sites near the power plant in both summer and winter inhibited cell proliferation and induced increased frequencies of V79 cell death, apoptosis, and necrosis. The cytotoxicity observed may be associated with the presence of higher concentration of inorganic elements, especially aluminum, silicon, sulfur, titanium and zinc at sites 1 and 2 in the stream, as well as with the complex mixture present in the coal, in both seasons. Therefore, the results obtained point to the toxicity potential of water samples with the influence of coal mining and combustion processes and the possible adverse effects on the health of exposed organisms.

Differential cytotoxic and inflammatory potency of amorphous silicon dioxide nanoparticles of similar size in multiple cell lines

The likelihood of environmental and health impacts of silicon dioxide nanoparticles (SiNPs) has risen, due to their increased use in products and applications. The biological potency of a set of similarly-sized amorphous SiNPs was investigated in a variety of cells to examine the influence of physico-chemical and biological factors on their toxicity. Cellular LDH and ATP, BrdU incorporation, resazurin reduction and cytokine release were measured in human epithelial A549, human THP-1 and mouse J774A.1 macrophage cells exposed for 24 h to suspensions of 5-15, 10-20 and 12 nm SiNPs and reference particles. The SiNPs were characterized in dry state and in suspension to determine their physico-chemical properties. The dose-response data were simplified into particle potency estimates to facilitate the comparison of multiple endpoints of biological effects in cells. Mouse macrophages were the most sensitive to SiNP exposures. Cytotoxicity of the individual cell lines was correlated while the cytokine responses differed, supported by cell type-specific differences in inflammation-associated pathways. SiNP (12 nm), the most cytotoxic and inflammogenic nanoparticle had the highest surface acidity, dry-state agglomerate size, the lowest trace metal and organics content, the smallest surface area and agglomerate size in suspension. Particle surface acidity appeared to be the most significant determinant of the overall biological activity of this set of nanoparticles. Combined with the nanoparticle characterization, integration of the biological potency estimates enabled a comprehensive determination of the cellular reactivity of the SiNPs. The approach shows promise as a useful tool for first-tier screening of SiNP toxicity.

Surface Water Impacted by Rural Activities Induces Genetic Toxicity Related to Recombinagenic Events in Vivo

This investigation assessed the interaction of surface water samples with DNA to quantitatively and qualitatively characterize their mutagenic and/or recombinagenic activity. Samples were obtained at three different sites along the Tocantins River (Tocantins State, Brazil). The area has withstood the impact mainly of rural activities, which release different chemical compounds in the environment. The Drosophila melanogaster Somatic Mutation and Recombination Test (SMART) was performed in standard (ST) and high bioactivation (HB) crosses. SMART is useful for the detection of mutational and recombinational events induced by genotoxins of direct and indirect action. Results demonstrated that samples collected in both seasons were able to induce increments on the mutant spot frequencies in the larvae of the HB cross. Genotoxicity was related to a massive recombinagenic activity. The positive responses ascribed to only the HB cross means that it is linked to pro-genotoxins requiring metabolic activation. The SMART wing test in Drosophila melanogaster was shown to be highly sensitive to detect genotoxic agents present in the aquatic environment impacted by agriculture.

Environmental, Inhaled and Ingested Causes of Pulmonary Fibrosis

Pulmonary fibrosis is a general term that refers to a collection of connective tissue around alveolar structures. There are over 200 disorders where the lungs may be involved in a fibrotic response. To determine the cause of pulmonary fibrosis requires an in depth understanding of the pathogenesis of pulmonary fibrosis and breadth of knowledge of the causative agents and associated disorders that may lead to pulmonary fibrosis. A comprehensive evaluation of the patient is absolutely essential, starting with detailed history that includes an occupational and environmental history because fibrogenic exposures can occur in many settings. Equally important is a history of ingestion of pharmaceutical or nonpharmaceutical substances. A physical examination and judicious investigations are always a part of any comprehensive clinical assessment but they are not commonly helpful in elucidating the cause of most pulmonary fibrotic disorders. Although, a chest film is invariably done, a logical and strongly recommended next step is a high-resolution computed tomography (HRCT). HRCT provides a better assessment of the radiological pattern, may suggest a diagnosis as well as direct the site, and type of lung biopsy. If the history and investigations do not lead to a diagnosis then a lung biopsy is required. Prevention or removal of the inciting agent is critical to the treatment of these disorders and in some instances corticosteroids may be of help.

Different reactivity of primary fibroblasts and endothelial cells towards crystalline silica: A surface radical matter

Quartz is a well-known occupational fibrogenic agent able to cause fibrosis and other severe pulmonary diseases such as silicosis and lung cancer. The silicotic pathology owes its severity to the structural and chemo-physical properties of the particles such as shape, size and abundance of surface radicals. In earlier studies, we reported that significant amounts of surface radicals can be generated on crystalline silica by chemical aggression with ascorbic acid (AA), a vitamin naturally abundant in the lung surfactant, and this reaction led to enhanced cytotoxicity and production of inflammatory mediators in a macrophage cell line. However in the lung, other cells acting in the development of silicosis, like fibroblasts and endothelial cells, can come to direct contact with inhaled quartz. We investigated the cytotoxic/pro-inflammatory effects of AA-treated quartz microcrystals (QA) in human primary fibroblasts and endothelial cells as compared to unmodified microcrystals (Q). Our results show that, in fibroblasts, the abundance of surface radicals on quartz microcrystals (Q vs QA) significantly enhanced cell proliferation (with or without co-culture with macrophages), reactive oxygen species (ROS) production, NF-κB nuclear translocation, smooth muscle actin, fibronectin, Bcl-2 and tissue inhibitor of metalloproteinase-1 expression and collagen production. Contrariwise, endothelial cells reacted to the presence of quartz microcrystals independently from the abundance of surface radicals showing similar levels of cytotoxicity, ROS production, cell migration, MCP-1, ICAM-I and fibronectin gene expression when challenged with Q or QA. In conclusion, our in vitro experimental model demonstrates an important and quite unexplored direct contribute of silica surface radicals to fibroblast proliferation and fibrogenic responses.

Cell-Based Therapy for Silicosis

Silicosis is the most common pneumoconiosis globally, with higher prevalence and incidence in developing countries. To date, there is no effective treatment to halt or reverse the disease progression caused by silica-induced lung injury. Significant advances have to be made in order to reduce morbidity and mortality related to silicosis. In this review, we have highlighted the main mechanisms of action that cause lung damage by silica particles and summarized the data concerning the therapeutic promise of cell-based therapy for silicosis.

Acute Exposure to Crystalline Silica Reduces Macrophage Activation in Response to Bacterial Lipoproteins

Numerous studies have examined the relationship between alveolar macrophages (AMs) and crystalline silica (SiO2) using in vitro and in vivo immunotoxicity models; however, exactly how exposure to SiO2 alters the functionality of AM and the potential consequences for immunity to respiratory pathogens remains largely unknown. Because recognition and clearance of inhaled particulates and microbes are largely mediated by pattern recognition receptors (PRRs) on the surface of AM, we hypothesized that exposure to SiO2 limits the ability of AM to respond to bacterial challenge by altering PRR expression. Alveolar and bone marrow-derived macrophages downregulate TLR2 expression following acute SiO2 exposure (e.g., 4 h). Interestingly, these responses were dependent on interactions between SiO2 and the class A scavenger receptor CD204, but not MARCO. Furthermore, SiO2 exposure decreased uptake of fluorescently labeled Pam2CSK4 and Pam3CSK4, resulting in reduced secretion of IL-1β, but not IL-6. Collectively, our data suggest that SiO2 exposure alters AM phenotype, which in turn affects their ability to uptake and respond to bacterial lipoproteins.

Evaluation of the genotoxic potential of soil contaminated with mineral coal tailings on snail Helix aspersa

Coal remains an important source of energy, although the fuel is a greater environmental pollutant. Coal is a mixture of several chemicals, especially inorganic elements and polycyclic aromatic hydrocarbons (PAH). Many of these compounds have mutagenic and carcinogenic effects on organisms exposed to this mineral. In the town of Charqueadas (Brazil), the tailings from mining were used for landfill in the lower areas of the town, and the consequence is the formation of large deposits of this material. The purpose of this study was to evaluate the genotoxic potential of soil samples contaminated by coal waste in different sites at Charqueadas, using the land snail Helix aspersa as a biomonitor organism. Thirty terrestrial snails were exposed to different treatments: 20 were exposed to the soil from two different sites in Charqueadas (site 1 and 2; 10 in each group) and 10 non-exposed (control group). Hemolymph cells were collected after 24h, 5days and 7days of exposure and comet assay, micronucleus test, oxidative stress tests were performed. Furthermore, this study quantified the inorganic elements present in soil samples by the PIXE technique and polycyclic aromatic hydrocarbons (PAH) by HPLC. This evaluation shows that, in general, soils from sites in Charqueadas, demonstrated a genotoxic effect associated with increased oxidative stress, inorganic and PAH content. These results demonstrate that the coal pyrite tailings from Charqueadas are potentially genotoxic and that H. aspersa is confirmed to be a sensitive instrument for risk assessment of environmental pollution.

Cysteine cathepsins and cystatins: from ancillary tasks to prominent status in lung diseases

Human cysteine cathepsins (family C1, clan CA) have long been regarded as ubiquitous household enzymes, primarily involved in the recycling and degradation of proteins in lysosomes. This opinion has changed considerably during recent decades, however, with the demonstration of their involvement in various physiological processes. A growing body of evidence supports the theory that cathepsins play specific functions in lung homeostasis and pathophysiological events such as asthma, lung fibrosis (including idiopathic pulmonary fibrosis), chronic obstructive pulmonary disease (embracing emphysema and chronic bronchitis), silicosis, bronchopulmonary dysplasia or tumor invasion. The objective of this review is to provide an update on the current knowledge of the role of these enzymes in the lung. Particular attention has been paid to the understanding of the role of these proteases and their natural inhibitors, cystatins (family I25, clan IH), in TGF-β1-driven fibrotic processes with an emphasis on lung fibrosis.

Attenuation of Nitrogen Mustard-Induced Pulmonary Injury and Fibrosis by Anti-Tumor Necrosis Factor-α Antibody

Nitrogen mustard (NM) is a bifunctional alkylating agent that causes acute injury to the lung that progresses to fibrosis. This is accompanied by a prominent infiltration of macrophages into the lung and upregulation of proinflammatory/profibrotic cytokines including tumor necrosis factor (TNF)α. In these studies, we analyzed the ability of anti-TNFα antibody to mitigate NM-induced lung injury, inflammation, and fibrosis. Treatment of rats with anti-TNFα antibody (15 mg/kg, iv, every 9 days) beginning 30 min after intratracheal administration of NM (0.125 mg/kg) reduced progressive histopathologic alterations in the lung including perivascular and peribronchial edema, macrophage/monocyte infiltration, interstitial thickening, bronchiolization of alveolar walls, fibrin deposition, emphysema, and fibrosis. NM-induced damage to the alveolar-epithelial barrier, measured by bronchoalveolar lavage (BAL) protein and cell content, was also reduced by anti-TNFα antibody, along with expression of the oxidative stress marker, heme oxygenase-1. Whereas the accumulation of proinflammatory/cytotoxic M1 macrophages in the lung in response to NM was suppressed by anti-TNFα antibody, anti-inflammatory/profibrotic M2 macrophages were increased or unchanged. Treatment of rats with anti-TNFα antibody also reduced NM-induced increases in expression of the profibrotic mediator, transforming growth factor-β. This was associated with a reduction in NM-induced collagen deposition in the lung. These data suggest that inhibiting TNFα may represent an efficacious approach to mitigating lung injury induced by mustards.

Asian sand dust aggregate causes atopic dermatitis-like symptoms in Nc/Nga mice

Background

Asian sand dust (ASD) originates from the arid and semiarid areas of China, and epidemiologic studies have shown that ASD exposure is associated with various allergic and respiratory symptoms. However, few studies have been performed to assess the relationship between skin inflammation and ASD exposure.

Methods

Twelve-week-old NC/Nga mice were divided into 6 groups (n = 8 for each group): hydrophilic petrolatum only (control); hydrophilic petrolatum plus ASD (ASD); hydrophilic petrolatum and heat inactivated-ASD (H-ASD); Dermatophagoides farinae extract (Df); Df and ASD (Df + ASD), and; Df and H-ASD (Df + H-ASD). The NC/Nga mice in each group were subjected to treatment twice a week for 4 weeks. We evaluated skin lesions by symptoms, pathologic changes, and serum IgE levels.

Results

ASD alone did not induce atopic dermatitis (AD)-like skin symptoms. However, Df alone, Df + H-ASD and Df + ASD all induced AD-like symptoms, and dermatitis scores in the group of Df + ASD group were significantly greater than that of the Df group (P = 0.0011 at day 21; and P = 0.017 at day 28). Mean serum IgE was markedly increased in the Df and Df + ASD groups, compared to the ASD and control groups (P < 0.0001), and serum IgE levels in the Df + ASD group were significantly higher compared to the Df group (P = 0.003).

Conclusions

ASD alone did not cause AD-like symptoms in NC/Nga mice. However, AD-like symptoms induced by Df, a major allergen, were enhanced by adding ASD. Although no epidemiological studies have been conducted for the association between ASD and symptoms of dermatitis, our data suggest that it is likely that ASD may contribute to the exacerbation of not only respiratory symptoms, but also skin diseases, in susceptible individuals.

Cancer risk among patients with coal workers' pneumoconiosis in Taiwan: a nationwide population-based study

This study is aimed to evaluate the cancer risk among patients with coal workers' pneumoconiosis (CWP) using a nationwide population-based dataset. Patients without previous cancer who had been diagnosed with CWP and followed-up for more than 1 year between 1997 and 2006 were recruited from the Taiwan National Health Insurance database. Standardized incidence ratios (SIRs) of cancers in CWP patients were calculated and compared to the cancer incidence in the general population. Risk factors for cancer development were also analyzed. After a median follow-up of 9.68 years, 954 cancers developed among 8,051 recruited CWP patients, with a follow-up of 69,398 person-years. The SIR for all cancers was 1.12 [95% confidence interval (CI) 1.04-1.18]. Males older than 80 years had a SIR of 1.27 (95% CI: 1.06-1.51). The SIRs of esophageal (1.76, 95% CI: 1.24-2.44), gastric (1.42, 95% CI: 1.13-1.76), liver and biliary tract (1.18, 95% CI: 1.01-1.37) and lung and mediastinal (1.45, 95% CI: 1.26-1.66) cancers were significantly higher in the CWP group than in the general population. Multivariate analysis showed that age ≥ 60 years [hazard ratio (HR) 1.70, 95% CI: 1.41-2.05), male gender (HR = 1.79, 95% CI: 1.44-2.23) and liver cirrhosis (HR = 3.99, 95% CI: 2.89-5.51) were significant predictors of cancer development in patients with CWP. We concluded that patients with CWP, especially elderly males, were at increased risk of cancer. Age, male gender and liver cirrhosis were independent risk factors for cancer development.

Occupational exposure to crystalline silica at Alberta work sites

Although crystalline silica has been recognized as a health hazard for many years, it is still encountered in many work environments. Numerous studies have revealed an association between exposure to respirable crystalline silica and the development of silicosis and other lung diseases including lung cancer. Alberta Jobs, Skills, Training and Labour conducted a project to evaluate exposure to crystalline silica at a total of 40 work sites across 13 industries. Total airborne respirable dust and respirable crystalline silica concentrations were quite variable, but there was a potential to exceed the Alberta Occupational Exposure Limit (OEL) of 0.025 mg/m(3) for respirable crystalline silica at many of the work sites evaluated. The industries with the highest potentials for overexposure occurred in sand and mineral processing (GM 0.090 mg/m(3)), followed by new commercial building construction (GM 0.055 mg/m(3)), aggregate mining and crushing (GM 0.048 mg/m(3)), abrasive blasting (GM 0.027 mg/m(3)), and demolition (GM 0.027 mg/m(3)). For worker occupations, geometric mean exposure ranged from 0.105 mg/m(3) (brick layer/mason/concrete cutting) to 0.008 mg/m(3) (dispatcher/shipping, administration). Potential for GM exposure exceeding the OEL was identified in a number of occupations where it was not expected, such as electricians, carpenters and painters. These exposures were generally related to the specific task the worker was doing, or arose from incidental exposure from other activities at the work site. The results indicate that where there is a potential for activities producing airborne respirable crystalline silica, it is critical that the employer include all worker occupations at the work site in their hazard assessment. There appears to be a relationship between airborne total respirable dust concentration and total respirable dust concentrations, but further study is require to fully characterize this relationship. If this relationship holds true, it may provide a useful hazard assessment tool for employers by which the potential for exposure to airborne respirable silica at the work site can be more easily estimated.