Lung oxidative response after acute coal dust exposure

Unraveling chromosomal and genotoxic damage in individuals occupationally exposed to coal from underground mining

Purpose

Coal mining is a vital sector in Colombia, contributing significantly to the nation's economy and the development of its regions. However, despite its importance, it has led to a gradual decline in the health of mine workers and nearby residents. While the adverse health effects of open-pit coal mining on exposed individuals have been well-documented in Colombia and globally, studies investigating genetic damage in underground coal miners are lacking.

Methods

The aim of our study was to evaluate chromosomal and genotoxic damage, in peripheral blood samples from a group of underground coal miners and residents of areas exposed to coal, in the town of Samacá, Boyacá-Colombia, and in a group of unexposed individuals by using banding and molecular cytogenetic techniques, as well as cytokinesis block micronucleus assays.

Results

Our results suggest that occupational exposure to coal induces chromosomal and genotoxic damage in somatic cells of underground coal miners. Chromosomal and genotoxic damage is an important step in carcinogenesis and the development of many other diseases. Our findings provide valuable insights into the effects of coal dust exposure on chromosomal integrity and genetic stability.

Conclusion

Our pilot study suggests that occupational exposure to coal induces chromosomal damage in underground coal miners, highlighting the importance of validating these findings with a larger sample size. Our results highlight the need to implement prevention and protection measures, as well as educational programs for underground coal miners. Characterizing and estimating exposure risks are extremely important for the safety of people exposed occupationally and environmentally to coal and its derivatives.

The impact of coal mine dust characteristics on pathways to respiratory harm: investigating the pneumoconiotic potency of coals

Exposure to dust from the mining environment has historically resulted in epidemic levels of mortality and morbidity from pneumoconiotic diseases such as silicosis, coal workers' pneumoconiosis (CWP), and asbestosis. Studies have shown that CWP remains a critical issue at collieries across the globe, with some countries facing resurgent patterns of the disease and additional pathologies from long-term exposure. Compliance measures to reduce dust exposure rely primarily on the assumption that all "fine" particles are equally toxic irrespective of source or chemical composition. For several ore types, but more specifically coal, such an assumption is not practical due to the complex and highly variable nature of the material. Additionally, several studies have identified possible mechanisms of pathogenesis from the minerals and deleterious metals in coal. The purpose of this review was to provide a reassessment of the perspectives and strategies used to evaluate the pneumoconiotic potency of coal mine dust. Emphasis is on the physicochemical characteristics of coal mine dust such as mineralogy/mineral chemistry, particle shape, size, specific surface area, and free surface area-all of which have been highlighted as contributing factors to the expression of pro-inflammatory responses in the lung. The review also highlights the potential opportunity for more holistic risk characterisation strategies for coal mine dust, which consider the mineralogical and physicochemical aspects of the dust as variables relevant to the current proposed mechanisms for CWP pathogenesis.

Understanding the pathogenesis of occupational coal and silica dust-associated lung disease

Workers in the mining and construction industries are at increased risk of respiratory and other diseases as a result of being exposed to harmful levels of airborne particulate matter (PM) for extended periods of time. While clear links have been established between PM exposure and the development of occupational lung disease, the mechanisms are still poorly understood. A greater understanding of how exposures to different levels and types of PM encountered in mining and construction workplaces affect pathophysiological processes in the airways and lungs and result in different forms of occupational lung disease is urgently required. Such information is needed to inform safe exposure limits and monitoring guidelines for different types of PM and development of biomarkers for earlier disease diagnosis. Suspended particles with a 50% cut-off aerodynamic diameter of 10 µm and 2.5 µm are considered biologically active owing to their ability to bypass the upper respiratory tract's defences and penetrate deep into the lung parenchyma, where they induce potentially irreversible damage, impair lung function and reduce the quality of life. Here we review the current understanding of occupational respiratory diseases, including coal worker pneumoconiosis and silicosis, and how PM exposure may affect pathophysiological responses in the airways and lungs. We also highlight the use of experimental models for better understanding these mechanisms of pathogenesis. We outline the urgency for revised dust control strategies, and the need for evidence-based identification of safe level exposures using clinical and experimental studies to better protect workers' health.

Associations of SMAD4 rs10502913 and NLRP3 rs1539019 Polymorphisms with Risk of Coal Workers’ Pneumoconiosis Susceptibility in Chinese Han Population

Purpose

CWP is an untreatable but preventable fibrotic lung disease caused by the chronic inhalation of coal dust. Genetic factors such as polymorphisms play an important role in the development of CWP. The present study investigated the association between the polymorphisms of SMAD4 and NLRP3 and CWP risk in a Chinese Han population.

Patients and Methods

SMAD4 rs10502913 and NLRP3rs1539019 polymorphisms were examined in 292 CWP subjects and 315 coal dust-exposed controls. The genotypes were analyzed using direct sequencing. The allele and genotype proportion between the cases and controls were compared using the chi-square test.

Results

The AG and GG genotypes of SMAD4 rs10502913 were not associated with altered CWP risk compared with AA genotype (adjusted OR = 1.535 and 1.426, 95% CI = 0.785–3.000 and 0.732–2.781, p = 0.210 and 0.297, respectively). Also, the NLRP3 rs1539019 heterozygous and homozygous variants CA and CC genotypes were not associated with the risk of CWP compared with the AA genotype (adjusted OR = 0.985 and 1.127, 95% CI = 0.652–1.489 and 0.713–1.782, p = 0.944 and 0.608, respectively). In addition, there was no interaction between SMAD4 rs10502913 and NLRP3 rs1539019 genotypes and smoking status on CWP risk in the stratified analyses.

Conclusion

In this present study, SMAD4 rs10502913 and NLRP3 rs1539019 genotypes were not associated with altered CWP risk in the Chinese Han population. Large sample sizes and multicenter studies are needed to elucidate these results in the future.

Pulmonary oxidative stress in wild bats exposed to coal dust: A model to evaluate the impact of coal mining on health

This study aimed to verify possible alterations involving histological and oxidative stress parameters in the lungs of wild bats in the Carboniferous Basin of Santa Catarina (CBSC) state, Southern Brazil, as a means to evaluate the impact of coal dust on the health of wildlife. Specimens of frugivorous bat species Artibeus lituratus and Sturnira lilium were collected from an area free of coal dust contamination and from coal mining areas. Chemical composition, histological parameters, synthesis of oxidants and antioxidant enzymes, and oxidative damage in the lungs of bats were analyzed. Levels of Na, Cl, Cu, and Br were higher in both species collected in the CBSC than in the controls. Levels of K and Rb were higher in A. lituratus, and levels of Si, Ca, and Fe were higher in S. lilium collected in the carboniferous basin. Both bat species inhabiting the CBSC areas exhibited an increase in the degree of pulmonary emphysema compared to their counterparts collected from control areas. Sturnira lilium showed increased reactive oxygen species (ROS) and 2',7'-dichlorofluorescein (DCF) levels, while A. lituratus showed a significant decrease in nitrite levels in the CBSC samples. Superoxide dismutase (SOD) activity did not change significantly; however, the activity of catalase (CAT) and levels of glutathione (GSH) decreased in the A. lituratus group from CBSC compared to those in the controls. There were no differences in NAD(P)H quinone dehydrogenase 1 protein (NQO1) abundance or nitrotyrosine expression among the different groups of bats. Total thiol levels showed a significant reduction in A. lituratus from CBSC, while the amount of malondialdehyde (MDA) was higher in both A. lituratus and S. lilium groups from coal mining areas. Our results suggested that bats, especially A. lituratus, living in the CBSC could be used as sentinel species for harmful effects of coal dust on the lungs.

The influence of polymorphisms of xenobiotic-metabolizing and DNA repair genes in DNA damage, telomere length and global DNA methylation evaluated in open-cast coal mining workers

Coal plants represent one of the main sources of environmental pollution due to the combustion process of this mineral and the consequent release of gases and particles which, in significant quantities, can lead to a potential risk to health and the environment. The susceptibility of individuals to the genotoxic effects of coal mining can be modulated by genetic variations in the xenobiotic detoxification and DNA repair processes. The aim of this study was to evaluate if xenobiotic metabolism polymorphism, base excision repair polymorphisms and non-homologous end joining repair polymorphism, could modify individual susceptibility to genomic instability and epigenetic alterations induced in workers by occupational exposure to coal. In this study, polymerase chain reaction was used to examine the polymorphic sites. The sample population comprising 70 coal mine workers and 71 workers non-exposed to coal. Our results demonstrated the effect of individual genotypes on different biomarkers evaluated. Significant decrease in % of global DNA methylation were observed in CYP1A1 Val/- exposed individuals compared to CYP1A1 Ile/Ile individuals. Coal workers who carried the XRCC4 Ile/Ile genotype showed decrease NBUD frequencies, while the XRCC4 Thr/- genotype was associated with decrease in Buccal micronucleus cells for the group not exposed. No influence of GSTM1 null, GSTT1 null, GSTP1 Ile105Val, hOGG1 Ser326Cys, XRCC1 Arg194Trp polymorphisms was observed. Thus, the current study reinforces the importance of considering the effect of metabolizing and repair variant genotypes on the individual susceptibility to incorporate DNA damage, as these processes act in a coordinated manner to determine the final response to coal exposure.

Seasonal variations in fine particle composition from Beijing prompt oxidative stress response in mouse lung and liver

Exposure to air pollution can induce oxidative stress, inflammation and adverse health effects. To understand how seasonal and chemical variations drive health impacts, we investigated indications for oxidative stress and inflammation in mice exposed to water and organic extracts from urban fine particles/PM_2.5 (particles with aerodynamic diameter ≤ 2.5 μm) collected in Beijing, China. Higher levels of pollution components were detected in heating season (HS, winter and part of spring) PM_2.5 than in the non-heating season (NHS, summer and part of spring and autumn) PM_2.5. HS samples were high in metals for the water extraction and high in polycyclic aromatic hydrocarbons (PAHs) for the organic extraction compared to their controls. An increased inflammatory response was detected in the lung and liver following exposure to the organic extracts compared to the water extracts, and mostly in the HS PM_2.5. While reduced antioxidant response was observed in the lung, it was activated in the liver, again, more in the HS extracts. Nrf2 transcription factor, a master regulator of stress response that controls the basal oxidative capacity and induces the expression of antioxidant response, and its related genes were induced. In the liver, elevated levels of lipid peroxidation adducts were measured, correlated with histologic analysis that revealed morphologic features of cell damage and proliferation, indicating oxidative and toxic damage. In addition, expression of genes related to detoxification of PAHs was observed. Altogether, the study suggests that the acute effects of PM_2.5 can vary seasonally with stronger health effects in the HS than in the NHS in Beijing, China and that some secondary organs may be susceptible for the exposure damage. Specifically, the liver is a potential organ influenced by exposure to organic components such as PAHs from coal or biomass burning and heating.

Neopterin as a marker for immune system activation in coal workers' pneumoconiosis

Coal workers' pneumoconiosis (CWP) is an occupational pulmonary disease that occurs by chronic inhalation of coal dust. Coal workers' pneumoconiosis is divided into two categories depending on the extent of the disease as simple pneumoconiosis (SP) and progressive massive fibrosis (PMF). Development of CWP is associated with the activation of the immune system. Neopterin is a predictive biochemical marker of cell-mediated immune activation and elevated levels of neopterin are detected in body fluids of patients with immune-related diseases. The present study was aimed to investigate whether increased serum, urine and bronchoalveolar lavage (BAL) fluid levels of neopterin is associated with the development and/or severity of CWP. Mean serum neopterin levels in SP and PMF patients (10.72 ± 0.98 nmol/L; 14.08 ± 3.86 nmol/L, respectively) were significantly higher than those of control group (5.30 ± 0.47nmol/L) ( P < 0.05). Although urinary neopterin levels were also increased in SP and PMF patients (235.17 ± 7.40 μmol/mol creatinine; 256.05 ± 9.43 μmol/mol creatinine, respectively) as compared with the control group (140.00 ± 5.43 μmol/mol creatinine) ( P < 0.01), they were within the normal concentration range. No significant difference was observed between serum and urinary neopterin levels of SP and PMF patients. A correlation was observed between serum and urinary neopterin levels of all subjects ( r = 0.525, P < 0.01). Bronchoalveolar lavage fluid neopterin levels were significantly higher in patients with SP and PMF (22.67 ± 2.9 nmol/L; 41.67 ± 8.68nmol/L, respectively) compared with control subjects (6.264 ± 1.74 nmol/L) ( P < 0.05, P < 0.01, respectively). The levels of neopterin in BAL fluid were also significantly higher in patients with PMF than in those with SP ( P < 0.05). These findings indicate that elevated serum and BAL levels of neopterin may be considered as a suitable biomarker for the assessment of CWP. Toxicology and Industrial Health 2007; 23: 155—160.

Platelet Indices in Patients with Coal Workers' Pneumoconiosis

PURPOSE

Coal workers' pneumoconiosis (CWP) is caused by an accumulation of coal particles in the lung parenchyma. Reactive oxygen species (ROS) play an important role in the pathogenesis of CWP. It is well documented that ROS stimulate platelet activation, adhesion, and aggregation. The aim of the present study was to investigate the relationship between platelet indices and CWP.

METHODS

The demographic features, occupational and medical history, exposure time, and complete blood count of retired coal miners were retrospectively analysed. The control group comprised healthy subjects who had not worked underground. Chest radiographs were evaluated according to the CWP classification of the International Labour Office.

RESULTS

The study population was divided into following groups: 50 controls, 97 without CWP, 142 simple pneumoconiosis (SP), 157 progressive massive fibrosis (PMF). The platelet count, mean platelet volume (MPV), platelet distribution width (PDW), and plateletcrit (PCT) were significantly higher in patients with CWP compared to those in patients without CWP and controls. The platelet count, MPV, and PCT were higher in patients with PMF compared to those in the SP group (p < 0.05). The results of multiple logistic regression analyses indicated that the platelet count, MPV, and PCT were independently associated with the development of CWP.

CONCLUSIONS

Platelet indices may be considered as disease markers for pneumoconiosis in coal miners and as a useful indicator of the progression of pneumoconiosis.

Investigation of fine chalk dust particles' chemical compositions and toxicities on alveolar macrophages in vitro

The aim of the study is to investigate chemical compositions of fine chalk dust particles (chalk PM2.5) and examine their adverse effects on alveolar macrophages (AMs) in vitro. Morphologies and element concentrations of individual chalk particles were analyzed by using the quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA). The oxidative response of AMs and the potential to generate nitric oxide (NO) by luminol-dependent chemiluminescence (CL) and nitrate reductase method were assessed 4h following the treatment of AMs with differing dosages of fine chalk particles, respectively. Oxidative stress and cytotoxicity elicited by chalk PM2.5 were also examined. The results showed that fine chalk particles were mainly composed of gypsum, calcite, dolomite and a little amount of organic adhesives. Exposure to chalk PM2.5 at 100 μg mL(-1) or 300 μg mL(-1) significantly increased intracellular catalase, malondialdehyde, and NO levels and decreased superoxide dismutase level in AMs, leading to leakage of lactate dehydrogenase (LDH) and reduction of the cell viability. Furthermore, luminol-dependent CL from respiratory burst in AMs was enhanced. It was suggested that chalk PM2.5 could make oxidative damages on AMs and result in cytotoxicity, being likely attributed to excessive reactive oxygen species or reactive nitrogen species induced by mixture of fine gypsum and calcite/dolomite particles.

Altered gene expression in HepG2 cells exposed to a methanolic coal dust extract

Exposure to coal dust has been associated with different chronic diseases and mortality risk. This airborne pollutant is produced during coal mining and transport activities, generating environmental and human toxicity. The aim of this study was to determine the effects of a coal dust methanolic extract on HepG2, a human liver hepatocellular carcinoma cell line. Cells were exposed to 5-100ppm methanolic coal extract for 12h, using DMSO as control. MTT and comet assays were used for the evaluation of cytotoxicity and genotoxicity, respectively. Real time PCR was utilized to quantify relative expression of genes related to oxidative stress, xenobiotic metabolism and DNA damage. Coal extract concentrations did not induce significant changes in HepG2 cell viability after 12h exposure; however, 50 and 100ppm of the coal extract produced a significant increase in genetic damage index with respect to negative control. Compared to vehicle control, mRNA CYP1A1 (up to 163-fold), NQO1 (up to 4.7-fold), and GADD45B (up to 4.7-fold) were up regulated, whereas PRDX1, SOD, CAT, GPX1, XPA, ERCC1 and APEX1 remained unaltered. This expression profile suggests that cells exposed to coal dust extract shows aryl hydrocarbon receptor-mediated alterations, changes in cellular oxidative status, and genotoxic effects. These findings share some similarities with those observed in liver of mice captured near coal mining areas, and add evidence that living around these industrial operations may be negatively impacting the biota and human health.

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.

Effect of occupation on lipid peroxidation and antioxidant status in coal-fired thermal plant workers

BACKGROUND

Air pollution from coal-fired power units is large and varied, and contributes to a significant number of negative environmental and health effects. Reactive oxygen species (ROS) have been implicated in the pathogenesis of coal dust-induced toxicity in coal-fired power plants.

AIM

The aim of the study was to measure free radical damage and the antioxidant activity in workers exposed to varying levels of coal dust.

MATERIAL AND METHODS

The study population consisted of workers in coal handling unit, turbine unit, and boiler unit (n = 50 each), working in thermal power plant; and electricians (n = 50) from same department were taken as controls. Lipid peroxidation was measured by malondialdehyde (MDA) levels and antioxidant activity was determined by superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels. Statistical analysis was carried out by Student's unpaired t-test.

RESULT

MDA levels showed significant increase (P > 0.001) in the thermal power plant workers than the electricians working in the city. The levels of SOD and GPx were significantly higher (P > 0.001) in electricians as compared to subjects working in thermal plant. Among the thermal plant workers, the coal handling unit workers showed significant increase (P > 0.001) in MDA and significant decrease in SOD and GPx than the workers of boiler and turbine unit workers.

CONCLUSION

Oxidative stress due to increase in lipid peroxidation and decrease in antioxidant activity results from exposure to coal dust and coal combustion products during thermal plant activities.

Coal and tire burning mixtures containing ultrafine and nanoparticulate materials induce oxidative stress and inflammatory activation in macrophages

Ultra-fine and nano-particulate materials resulting from mixtures of coal and non-coal fuels combustion for power generation release to the air components with toxic potential. We evaluated toxicological and inflammatory effects at cellular level that could be induced by ultrafine/nanoparticles-containing ashes from burning mixtures of coal and tires from an American power plant. Coal fly ashes (CFA) samples from the combustion of high-S coal and tire-derived fuel, the latter about 2-3% of the total fuel feed, in a 100-MW cyclone utility boiler, were suspended in the cell culture medium of RAW 264.7 macrophages. Cell viability, assessed by MTT reduction, SRB incorporation and contrast-phase microscopy analysis demonstrated that CFA did not induce acute toxicity. However, CFA at 1mg/mL induced an increase of approximately 338% in intracellular TNF-α, while release of this proinflammatory cytokine was increased by 1.6-fold. The expression of the inflammatory mediator CD40 receptor was enhanced by 2-fold, the receptor for advanced glycation endproducts (RAGE) had a 5.7-fold increase and the stress response protein HSP70 was increased nearly 12-fold by CFA at 1mg/mL. Although CFA did not induce cell death, parameters of oxidative stress and reactive species production were found to be altered at several degrees, such as nitrite accumulation (22% increase), DCFH oxidation (3.5-fold increase), catalase (5-fold increase) and superoxide dismutase (35% inhibition) activities, lipoperoxidation (4.2 fold-increase) and sulfhydryl oxidation (40% decrease in free SH groups). The present results suggest that CFA containing ultra-fine and nano-particulate materials from coal and tire combustion may induce sub-chronic cell damage, as they alter inflammatory and oxidative stress parameters at the molecular and cellular levels, but do not induce acute cell death.

Coal mine dust lung disease. New lessons from old exposure

Coal mining remains a sizable industry, with millions of working and retired coal miners worldwide. This article provides an update on recent advances in the understanding of respiratory health issues in coal miners and focuses on the spectrum of disease caused by inhalation of coal mine dust, termed coal mine dust lung disease. In addition to the historical interstitial lung diseases (coal worker's pneumoconiosis, silicosis, and mixed dust pneumoconiosis), coal miners are at risk for dust-related diffuse fibrosis and chronic airway diseases, including emphysema and chronic bronchitis. Recent recognition of rapidly progressive pneumoconiosis in younger miners, mainly in the eastern United States, has increased the sense of urgency and the need for vigilance in medical research, clinical diagnosis, and exposure prevention. Given the risk for disease progression even after exposure removal, along with few medical treatment options, there is an important role for chest physicians in the recognition and management of lung disease associated with work in coal mining.

Identification of pathology from diesel exhaust particles in the bladder in a rat model by aspiration of particles from the pharynx

To determine whether diesel exhaust particles (DEPs) could be a toxic agent to the bladder, rats were exposed to different concentrations of DEPs for one month or three months. When the rats were sacrificed, morphologic changes of the urothelium were investigated. The antioxidase activity and the levels of lipid peroxidation in the bladder were assayed. In the three-month group, DEPs at doses of 21.03 μg/μl insulted the structural integrity of surface glycosaminoglycans, widened the gap between urothelial cells, increased levels of lipid peroxidation, and decreased antioxidase activities in the urinary bladder (p<0.05). Furthermore, DEPs at a dose of 5.61 μg/μl decreased glutathione, catalase, and glutathione peroxidase activities (p<0.05). These results led to the conclusion that DEPs were a toxic agent in the bladder. The toxic effects might be attributed to oxidative damage mediated by pro-oxidant/antioxidant imbalance or excessive free radicals.

Antioxidant intervention compensates oxidative stress in blood of subjects exposed to emissions from a coal electric-power plant in South Brazil

In the process of energy generation, particulate matter (PM) emissions derived from coal combustion expose humans to serious occupational diseases, which are associated with overgeneration of reactive oxygen species (ROS). The purpose of the present study is to better understand the relations between PM exposure derived from a coal electric-power plant and the oxidative damage in subjects (n=20 each group) directly (working at the burning area) or indirectly (working at the office or living in the vicinity of the electric-power plant=group of residents) exposed to airborne contamination, before and after daily supplementation with vitamins C (500mg) and E (800mg) during six months, which were compared to non-exposed subjects (control group). Several biomarkers of oxidative stress were examined such as levels of thiobarbituric acid reactive substances (TBARS), protein carbonyls (PC), protein thiols (PT) and vitamin E in plasma, levels of reduced glutathione (GSH) in whole blood, and of activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) in red cells. Before supplementation, TBARS and PC levels were significantly increased, levels of GSH and vitamin E were decreased, while the activities of SOD and CAT were increased in workers groups and GST were increased in all groups in compared to controls. After the antioxidant supplementation essentially all these biomarkers were normalized to control levels. The antioxidant intervention was able to confer a protective effect of vitamins C and E against the oxidative insult associated with airborne contamination derived from coal burning of an electric-power plant.

Increased occupational coal dust toxicity in blood of central heating system workers

Coal dust causes lung diseases in occupational exposure. Reactive oxygen species have been implicated in the pathogenesis of its toxicity. In this study, serum enzymes, lipid profile and other biochemical values with oxidant/antioxidant status in whole blood and serum of central heating system workers (CHSW; the persons responsible for heating the apartment with coal) were determined to reflect the cell injury. Blood samples were obtained from CHSW (n = 25) and healthy individuals (n = 25). All values were measured in whole blood and serum. ANOVA was used for the estimation of statistical data. In the group of CHSW, creatinine, ferritin, alanin aminotransferase, aspartate aminotransferase, creatine phosphokinase, gamma glutamyl transferase, lactate dehydrogenase and glutathione reductase activities as well as triglyceride, very low density lipoprotein, protein carbonyl and malondialdehide were significantly higher, while transferrin, high density lipoprotein and catalase (CAT) activities were lower than the group of healthy individuals. This result is consistent with hypothesis that respirable coal dust generates lipid and protein oxidation and induces leakage of serum enzymes by cell damage. It also leads to imbalance in antioxidant defense system, lipid profile and other biochemical parameters.

Coal dust alters beta-naphthoflavone-induced aryl hydrocarbon receptor nuclear translocation in alveolar type II cells

BACKGROUND

Many polycyclic aromatic hydrocarbons (PAHs) can cause DNA adducts and initiate carcinogenesis. Mixed exposures to coal dust (CD) and PAHs are common in occupational settings. In the CD and PAH-exposed lung, CD increases apoptosis and causes alveolar type II (AT-II) cell hyperplasia but reduces CYP1A1 induction. Inflammation, but not apoptosis, appears etiologically associated with reduced CYP1A1 induction in this mixed exposure model. Many AT-II cells in the CD-exposed lungs have no detectable CYP1A1 induction after PAH exposure. Although AT-II cells are a small subfraction of lung cells, they are believed to be a potential progenitor cell for some lung cancers. Because CYP1A1 is induced via ligand-mediated nuclear translocation of the aryl hydrocarbon receptor (AhR), we investigated the effect of CD on PAH-induced nuclear translocation of AhR in AT-II cells isolated from in vivo-exposed rats. Rats received CD or vehicle (saline) by intratracheal (IT) instillation. Three days before sacrifice, half of the rats in each group started daily intraperitoneal injections of the PAH, beta-naphthoflavone (BNF).

RESULTS

Fourteen days after IT CD exposure and 1 day after the last intraperitoneal BNF injection, AhR immunofluorescence indicated that proportional AhR nuclear expression and the percentage of cells with nuclear AhR were significantly increased in rats receiving IT saline and BNF injections compared to vehicle controls. However, in CD-exposed rats, BNF did not significantly alter the nuclear localization or cytosolic expression of AhR compared to rats receiving CD and oil.

CONCLUSION

Our findings suggest that during particle and PAH mixed exposures, CD alters the BNF-induced nuclear translocation of AhR in AT-II cells. This provides an explanation for the modification of CYP1A1 induction in these cells. Thus, this study suggests that mechanisms for reduced PAH-induced CYP1A1 activity in the CD exposed lung include not only the effects of inflammation on the lung as a whole, but also reduced PAH-associated nuclear translocation of AhR in an expanded population of AT-II cells.

Serum and BAL cytokine and antioxidant enzyme levels at different stages of pneumoconiosis in coal workers

Coal workers’ pneumoconiosis (CWP) is an occupational pulmonary disease that occurs by chronic inhalation of coal dust. CWP is divided into two stages depending on the extent of the disease, as simple pneumoconiosis (SP) and progressive massive fibrosis (PMF). In the present study, serum and bronchoalveolar lavage (BAL) cytokine (interleukin-1β [IL-1β], IL-6, tumor necrosis factor-α [TNF-α], transforming growth factor-β [TGF-β]) and antioxidant enzymes levels, their relation with the disease severity, and whether they can be considered as biological markers were investigated. Serum and BAL levels of IL-1β, IL-6, and TNF-α were higher in SP and PMF patient groups compared with that in active and retired miner groups. Serum and BAL IL-1β, IL-6, and TNF-α levels were also found to be higher in patients with PMF compared with the SP group. BAL superoxide dismutase (SOD), glutathione peroxidase, and catalase levels and serum SOD level were increased in both patient groups compared with the control group. In addition, mean serum and BAL TGF-β levels were found to be increased in patients with SP compared with PMF group. Based on these results, BAL and serum cytokine and antioxidant enzymes levels were evaluated and discussed as potential biomarkers for different stages of CWP.

Cytogenetic monitoring of coal workers and patients with coal workers' pneumoconiosis in Turkey

Occupational exposure to coal dust causes coal workers' pneumoconiosis (CWP), which is a chronic inflammatory and fibrotic lung disease. Recently, chronic inflammation has been accepted as a crucial factor in the pathogenesis of neoplasia. The chronic inflammation provides dynamic setting for oxidative stress and formation of free radicals. Interaction of reactive oxygen species (ROS) with DNA augments the likelihood of DNA structural and transcriptional errors. The purpose of this study was to investigate the genotoxic risk in pneumoconiotic patients and in those with occupational exposure to coal dust. Therefore, sister chromatid exchange (SCE) and micronucleus (MN) tests were performed in Turkish CWP patients, coal workers, and an unexposed control group. Both SCE and MN frequencies in CWP patients were found significantly higher than in coal worker and unexposed groups. There were no differences between SCE and MN frequencies of coal worker and unexposed groups. On the other hand, no correlation between SCE frequency, duration of exposure, and age was observed in all three groups. There was also no effect of smoking on the frequencies of SCE and MN in the groups. Based on these results, it might be suggested that development of CWP leads to a significant induction of cytogenetic damage in peripheral lymphocytes of CWP patients. This is the first report on CWP patients with elevated cytogenetic endpoints. Further, a larger follow-up study is warranted.

Exercício físico regular diminui o estresse oxidativo pulmonar em ratos após exposição aguda ao carvão mineral

Estudos têm apontado o exercício físico regular de baixa a moderada intensidade como um importante agente no combate ao estresse oxidativo. O objetivo deste estudo foi investigar o efeito do exercício físico regular na resposta oxidativa pulmonar após a inalação de pó de carvão mineral. Vinte e quatro ratos Wistar machos (200-250g) foram divididos aleatoriamente em dois grupos com respectivos controles (treinado, n = 6 e não-treinado, n = 6). Os animais receberam, por instilação traqueal, pó de carvão mineral (3mg/0,5ml salina, três dias/semana, durante três semanas) ou 0,5ml de solução salina 0,9%. Quarenta e oito horas após a última instilação, o grupo treinado foi submetido a um programa de exercício progressivo em esteira durante 12 semanas (até 17m.min-1, 50min.dia-1, 10% de inclinação). Quarenta e oito horas após a última sessão de treinamento, todos os animais foram mortos por decapitação e os pulmões e sóleo foram cirurgicamente removidos para posterior análise bioquímica. A atividade da citrato-sintase foi determinada no músculo sóleo e os danos em lipídios e proteínas foram avaliados nos pulmões pela concentração de TBARS e pela determinação de grupos carbonil, respectivamente. Os resultados mostram que a prática regular de exercício físico reduz significativamente os níveis presentes de TBARS em ratos treinados e diminui os níveis de oxidação em proteínas em ambos os grupos quando comparados com os respectivos controles. Os resultados nos levam a sugerir que o exercício físico regular em esteira é um agente capaz de amenizar os danos oxidativos pulmonares induzidos pela inalação de partículas de carvão mineral.

N-acetylcysteine and deferoxamine reduce pulmonary oxidative stress and inflammation in rats after coal dust exposure

Coal dust inhalation induces oxidative damage and inflammatory infiltration on lung parenchyma. Thus, the aim of this study was to determine whether N-acetylcysteine (NAC) administered alone or in combination with deferoxamine (DFX), significantly reduced the inflammatory infiltration and oxidative damage in the lungs of rats exposed to coal dust. Forty-two male Wistar rats (200-250 g) were exposed to the coal dust (3mg/0.5 mL saline, 3 days/week, for 3 weeks) by intratracheal instillation. The animals were randomly divided into three groups: saline 0.9% (n=8), supplemented with NAC (20mg/kg of body weight/day, intraperitoneal injection (i.p.)) (n=8), and supplemented with NAC (20 mg/kg of body weight/day, i.p.) plus DFX (20 mg/kg of body weight/week) (n=8). Control animals received only saline solution (0.5 mL). Lactate dehydrogenase activity and total cell number were determined in the bronchoalveolar lavage fluid. We determined lipid peroxidation and oxidative protein damage parameters and catalase and superoxide dismutase activities in the lungs of animals. Intratracheal instillation of coal dust in the lungs of rats led to an inflammatory response and induced significant oxidative damage. The administration of NAC alone or in association with DFX reduced the inflammatory response and the oxidative stress parameters in rats exposed to coal dust.

Effects of airborne fine particulate matter on antioxidant capacity and lipid peroxidation in multiple organs of rats

The purpose of this research was to determine whether airborne fine particulate matter (PM(2.5)) could increase levels of lipid peroxidation and alter intracellular redox status in multiple organs of rats. Thirty-two male Wistar rats were randomly divided into the treated groups using PM(2.5) at different dosages (1.5, 7.5, 37.5 mg/kg) and with a control group using saline. Rats were sacrificed 24 h after one-time intratracheal instillation. Then we investigated the activities of Cu, Zn-superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and the levels of glutathione (GSH) and thiobarbituric acid-reactive substances (TBARS) in hearts, livers, spleens, lungs, kidneys, brains, and testicles. It was found that PM(2.5) at dosages of 7.5 and 37.5 mg/kg significantly increased lipid peroxidation levels in the hearts, livers, lungs, and testicles, decreased SOD, CAT, and GPx activities in the lungs, livers, kidneys, and brains, and depleted GSH levels in all the measured organs compared to the control. There were also differences in the changes of antioxidative enzymes activities and lipid peroxidation levels in seven organs. These results led to a conclusion that airborne PM(2.5) was a systemic toxic agent, not only to respiratory and cardiovascular systems. Its toxic effects might be attributed to oxidative damage mediated by prooxidant/antioxidant imbalance or excess free radicals. Further work is required to explain the toxicity role of PM(2.5) on multiple organs of mammals.

Oxidative parameters differences during non-lethal and lethal sepsis development

BACKGROUND

The participation of oxidative stress in the development of sepsis is still unclear. The aim of this study was to determine which aspect of antioxidant/pro-oxidant has the major importance in differentiation between non-lethal and lethal sepsis.

MATERIALS AND METHODS

Non-lethal and lethal sepsis were induced by cecal ligation and puncture (CLP) in adult Wistar rats, using 18 and 14 gauge needle, respectively. Rats were sacrificed within 12, 24, 48, and 96 h and organs (heart, lung, diaphragm, liver, and kidney) were isolated. The main antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) were measured, as well as protein carbonyls and TBARS, as an index of oxidative damage.

RESULTS

Twelve hours after lethal sepsis induction we observed an increase in the oxidative damage in all of the organs studied. In contrast, during non-lethal sepsis, the oxidative damage occurs late in the course of the disease (after 48 h) and the increase in protein carbonyls is of less magnitude when compared to the lethal sepsis. During non-lethal sepsis, in contrast to the lethal sepsis, there is no sustained increase in the SOD/CAT relation.

CONCLUSIONS

The present study is the first report showing a different profile of oxidative damage when comparing non-lethal and lethal sepsis. The oxidative damage in proteins seems to be a differential parameter between non-lethal and lethal sepsis. In addition, the SOD/CAT imbalance seems to be an important factor in the oxidative stress during the lethal sepsis, but seems not to happen, in a sustained way, during the non-lethal sepsis.