Oxidative stress and cytokine expression in respiratory epithelial cells exposed to well-characterized aerosols from Kabul, Afghanistan

Acute and repeated exposures of normal human bronchial epithelial (NHBE) cells culture to particles from a coloured pyrotechnic smoke

Coloured pyrotechnic smokes are frequently used in the military field and occasionally by civilians, but their health hazards have been little studied. The main concern could rise from inhalation of smoke particles. Our previous study showed that acute exposure to particles from a red signalling smoke (RSS) induced an antioxidant and inflammatory responses in small airway epithelial cells. The aim of this study was to further explore the toxicity of RSS particles at a more proximal level of the respiratory tract, using normal human bronchial epithelial cells grown at the Air-Liquid Interface. Acute exposure (24 h) induced an oxidative stress that persisted 24 h post-exposure, associated with particle internalization and epithelium morphological changes (cuboidal appearance and loss of cilia). Repeated exposures (4×16h) to RSS particles did not trigger oxidative stress but cell morphological changes occurred. Overall, this study provides a better overview of the toxic effects of coloured smoke particles.

Extract of Pyrus nivalis enhances phagocytosis in lungs after particles matter exposure in BALB/c mice

During past few decades, studies have demonstrated that particulate matter (PM) is the most serious environmental pollutant in industrial countries which mainly contributes for increasing prevalence of chronic respiratory inflammatory diseases. Healthy food supplements to prevent the inflammatory diseases are common and show notable effects. The effects of the extract of Pyrus nivalis, a common fruit and herbal medicine in Taiwan, on PM-induced airway inflammation in mice were investigated by feeding the extract orally for 21 days. Results obtained from lung histology and bronchial alveolar lavage fluid (BALF) cell profile showed that oral feeding of P. nivalis extract did not affect the airway inflammation. However, it increased the phagocytic activity in BALF cells and induced M1-dominant macrophage differentiation in lungs. Our study showed that extract of P. nivalis might present the beneficial and therapeutic potential for clearance of PM and pathogens in airway. PRACTICAL APPLICATIONS: Pyrus nivalis is a common fruit and also used extensively in Chinese herbology. The pharmacological effects of P. nivalis have been reported in ancient Chinese Medical literature and known to possess anti-asthma and anti-cough properties as well as to enhance function of lungs. In this study, we found that orally feeding the extract of P. nivalis did not induce airway inflammation and affect particulate matter (PM)-induced inflammatory cells infiltration in lungs but increased phagocytosis with or without PM treatment which might indicate its therapeutic potential for clearance of PM and pathogens in airway.

Toxicity of iron nanoparticles towards primary cultures of human bronchial epithelial cells

Air pollution is a public health issue and the toxicity of ambient particulate matter (PM) is well-recognized. Although it does not mostly contribute to the total mass of PM, increasing evidence indicates that the ultrafine fraction has generally a greater toxicity than the others do. A better knowledge of the underlying mechanisms involved in the pathological disorders related to nanoparticles (NPs) remains essential. Hence, the goal of this study was to determine better whether the exposure to a relatively low dose of well-characterized iron-rich NPs (Fe-NPs) might alter some critical toxicological endpoints in a relevant primary culture model of human bronchial epithelial cells (HBECs). We sought to use Fe-NPs representative of those frequently found in the industrial smokes of metallurgical industries. After having noticed the effective internalization of Fe-NPs, oxidative, inflammatory, DNA repair, and apoptotic endpoints were investigated within HBECs, mainly through transcriptional screening. Taken together, these results revealed that, despite it only produced relatively low levels of reactive oxygen species without any significant oxidative damage, low-dose Fe-NPs quickly significantly deregulated the transcription of some target genes closely involved in the proinflammatory response. Although this inflammatory process seemed to stay under control over time in case of this acute scenario of exposure, the future study of its evolution after a scenario of repeated exposure could be very interesting to evaluate the toxicity of Fe-NPs better.

Impacts of stove/fuel use and outdoor air pollution on chemical composition of household particulate matter

Biomass combustion for cooking and heating releases particulate matter (PM_2.5 ) that contributes to household air pollution. Fuel and stove types affect the chemical composition of household PM, as does infiltration of outdoor PM. Characterization of these impacts can inform future exposure assessments and epidemiologic studies, but is currently limited. In this study, we measured chemical components of PM_2.5 (water-soluble organic matter [WSOM], ions, black carbon, elements, organic tracers) in rural Chinese households using traditional biomass stoves, semi-gasifier stoves with pelletized biomass, and/or non-biomass stoves. We distinguished households using one stove type (traditional, semi-gasifier, or LPG/electric) from those using multiple stoves/fuels. WSOM concentrations were higher in households using only semi-gasifier or traditional stoves (31%-33%) than in those with exclusive LPG/electric stove (13%) or mixed stove use (12%-22%). Inorganic ions comprised 14% of PM in exclusive LPG/electric households, compared to 1%-5% of PM in households using biomass. Total PAH content was much higher in households that used traditional stoves (0.8-2.8 mg/g PM) compared to those that did not (0.1-0.3 mg/g PM). Source apportionment revealed that biomass burning comprised 27%-84% of PM_2.5 in households using biomass. In all samples, identified outdoor sources (vehicles, dust, coal combustion, secondary aerosol) contributed 10%-20% of household PM_2.5 .

Evaluating the cytotoxicity of graphene oxide using embryonic stem cells-derived cells

Graphene oxide (GO) has several potential biomedical applications and therefore cytotoxic evaluation of GO is very important. However, the two most common in vitro models for testing cytotoxicity-primary human cells and immortalized cell lines-suffer serious limitations, namely limited supplies of cells and unrealistic cellular responses, respectively. Here, we demonstrate the use of embryonic stem cell (ESC)-derived cells to study GO cytotoxicity. We tested the use of retinal pigment epithelium (RPE) cells derived from three-dimensional human ESC cultures ("ESC-RPE" cells) as a model of GO cytotoxicity by exposing them to varying concentrations of GO nanosheets. For comparison, we also performed the same test with primary human retinal pigment epithelium cells ("hRPE"), and with cells derived from a human RPE cell line ("ARPE19" cells). We found that cytotoxicity metrics (viability, apoptosis, intracellular reactive oxygen species, and mitochondrial membrane potential) were very similar in ESC-RPE cells and hRPE cells, and those in ARPE19 cells were very different. We conclude that cell models of GO cytotoxicity derived from ESCs are an excellent alternative to primary human cells, without the limitations of tissue availability.

Pro-inflammatory effects of extracted urban fine particulate matter on human bronchial epithelial cells BEAS-2B

Atmospheric particulate matter (PM) constitutes the major part of urban air pollution and is a heterogeneous mixture of solid and liquid particles of different origin, size, and chemistry. Human exposure to PM in urban areas poses considerable and significant adverse effects on the respiratory system and human health in general. Major contributors to PM content are combustion-related sources such as diesel vehicles, household, and industrial heating. PM is composed of thousands of different high molecular weight organic compounds, including poly-aromatic hydrocarbons (PAHs). The aim of this study was to clarify the cytotoxic effects of the extract of actual urban PM1 with high benzo[a]pyrene (BaP) content collected in Eastern European mid-sized city during winter heating season on human bronchial epithelial cells (BEAS-2B). Decreased cell viability, alteration of cell layer integrity, increased apoptosis, and oxidative stress were observed during the 3-day exposure to the PM extract. In addition, following PM exposure pro-inflammatory cytokine expression was upregulated at gene and protein levels. Morphology and motility changes, i.e., decreased cells' ability to cover scratch area, were also documented. We report here that the extract of urban PM1 may induce bronchial epithelium changes and render it pro-inflammatory and compromised within 3 days.

PM2.5-induced oxidative stress increases intercellular adhesion molecule-1 expression in lung epithelial cells through the IL-6/AKT/STAT3/NF-κB-dependent pathway

BACKGROUND

Epidemiological studies have shown that ambient air pollution is closely associated with increased respiratory inflammation and decreased lung function. Particulate matters (PMs) are major components of air pollution that damages lung cells. However, the mechanisms remain to be elucidated. This study examines the effects of PMs on intercellular adhesion molecule-1 (ICAM-1) expression and the related mechanisms in vitro and in vivo.

RESULT

The cytotoxicity, reactive oxygen species (ROS) generation, and monocyte adherence to A549 cells were more severely affected by treatment with O-PMs (organic solvent-extractable fraction of SRM1649b) than with W-PMs (water-soluble fraction of SRM1649b). We observed a significant increase in ICAM-1 expression by O-PMs, but not W-PMs. O-PMs also induced the phosphorylation of AKT, p65, and STAT3. Pretreating A549 cells with N-acetyl cysteine (NAC), an antioxidant, attenuated O-PMs-induced ROS generation, the phosphorylation of the mentioned kinases, and the expression of ICAM-1. Furthermore, an AKT inhibitor (LY294002), NF-κB inhibitor (BAY11-7082), and STAT3 inhibitor (Stattic) significantly down-regulated O-PMs-induced ICAM-1 expression as well as the adhesion of U937 cells to epithelial cells. Interleukin-6 (IL-6) was the most significantly changed cytokine in O-PMs-treated A549 cells according to the analysis of the cytokine antibody array. The IL-6 receptor inhibitor tocilizumab (TCZ) and small interfering RNA for IL-6 significantly reduced ICAM-1 secretion and expression as well as the reduction of the AKT, p65, and STAT3 phosphorylation in O-PMs-treated A549 cells. In addition, the intratracheal instillation of PMs significantly increased the levels of the ICAM-1 and IL-6 in lung tissues and plasma in WT mice, but not in IL-6 knockout mice. Pre-administration of NAC attenuated those PMs-induced adverse effects in WT mice. Furthermore, patients with chronic obstructive pulmonary disease (COPD) had higher plasma levels of ICAM-1 and IL-6 compared to healthy subjects.

CONCLUSION

These results suggest that PMs increase ICAM-1 expression in pulmonary epithelial cells in vitro and in vivo through the IL-6/AKT/STAT3/NF-κB signaling pathway.

Urban particulate matter (PM) suppresses airway antibacterial defence

Background

Epidemiological studies have shown that urban particulate matter (PM) increases the risk of respiratory infection. However, the underlying mechanisms are poorly understood. PM has been postulated to suppress the activation of airway epithelial innate defence in response to infection.

Methods

The effects of PM on antibacterial defence were studied using an in vitro infection model. The levels of antimicrobial peptides were measured using RT-PCR and ELISA. In addition to performing colony-forming unit counts and flow cytometry, confocal microscopy was performed to directly observe bacterial invasion upon PM exposure.

Results

We found that PM PM increased bacterial invasion by impairing the induction of β-defensin-2 (hBD-2), but not the other antimicrobial peptides (APMs) secreted by airway epithelium. PM further increases bacteria-induced ROS production, which is accompanied by an accelerated cell senescence and a decrease in bacteria-induced hBD-2 production, and the antioxidant NAC treatment attenuates these effects. The PM exposure further upregulated the expression of IL-8 but downregulated the expression of IL-13 upon infection.

Conclusions

PM promotes bacterial invasion of airway epithelial cells by attenuating the induction of hBD-2 via an oxidative burst. These findings associate PM with an increased susceptibility to infection. These findings provide insight into the underlying mechanisms regarding the pathogenesis of particulate matter.

Biomass burning in the Amazon region causes DNA damage and cell death in human lung cells

Most of the studies on air pollution focus on emissions from fossil fuel burning in urban centers. However, approximately half of the world's population is exposed to air pollution caused by biomass burning emissions. In the Brazilian Amazon population, over 10 million people are directly exposed to high levels of pollutants resulting from deforestation and agricultural fires. This work is the first study to present an integrated view of the effects of inhalable particles present in emissions of biomass burning. Exposing human lung cells to particulate matter smaller than 10 µm (PM10), significantly increased the level of reactive oxygen species (ROS), inflammatory cytokines, autophagy, and DNA damage. Continued PM10 exposure activated apoptosis and necrosis. Interestingly, retene, a polycyclic aromatic hydrocarbon present in PM10, is a potential compound for the effects of PM10, causing DNA damage and cell death. The PM10 concentrations observed during Amazon biomass burning were sufficient to induce severe adverse effects in human lung cells. Our study provides new data that will help elucidate the mechanism of PM10-mediated lung cancer development. In addition, the results of this study support the establishment of new guidelines for human health protection in regions strongly impacted by biomass burning.

Evaluation of the toxicity of graphene oxide exposure to the eye

Graphene and its derivatives are the new carbon nanomaterials with the prospect for great applications in electronics, energy storage, biosensors and medicine. However, little is known about the toxicity of graphene or its derivatives in the case of occasional or repeated ocular exposure. We performed in vitro and in vivo studies to evaluate the toxicity of graphene oxide (GO) exposure to the eye. Primary human corneal epithelium cells (hCorECs) and human conjunctiva epithelium cells (hConECs) were exposed to GO (12.5-100 μg/mL). Acute GO exposure (2 h) did not induce cytotoxicity to hCorECs. However, short-term GO exposure (24 h) exerted significant cytotoxicity to hCorECs and hConECs with increased intracellular reactive oxygen species (ROS). Glutathione (GSH) reduced the GO-induced cytotoxicity. We further performed acute eye irritation tests in albino rabbits according to the Organization for Economic Cooperation and Development (OECD) guidelines, and the rabbits did not exhibit corneal opacity, conjunctival redness, abnormality of the iris, or chemosis at any time point after the instillation of 100 μg/mL of GO. However, 5-day repeated GO exposure (50 and 100 μg/mL) caused reversible mild corneal opacity, conjunctival redness and corneal epithelium damage to Sprague-Dawley rats, which was also alleviated by GSH. Therefore, our study suggests that GO-induced time- and dose-dependent cytotoxicity to hCorECs and hConECs via oxidative stress. Occasional GO exposure did not cause acute eye irritation; short-term repeated GO exposure generally resulted in reversible damage to the eye via oxidative stress, which may be alleviated by the antioxidant GSH.

Molecular mechanisms of dust-induced toxicity in human corneal epithelial cells: Water and organic extract of office and house dust

Human corneal epithelial (HCE) cells are continually exposed to dust in the air, which may cause corneal epithelium damage. Both water and organic soluble contaminants in dust may contribute to cytotoxicity in HCE cells, however, the associated toxicity mechanisms are not fully elucidated. In this study, indoor dust from residential houses and commercial offices in Nanjing, China was collected and the effects of organic and water soluble fraction of dust on primary HCE cells were examined. The concentrations of heavy metals in the dust and dust extracts were determined by ICP-MS and PAHs by GC-MS, with office dust having greater concentrations of heavy metals and PAHs than house dust. Based on LC50, organic extract was more toxic than water extract, and office dust was more toxic than house dust. Accordingly, the organic extracts induced more ROS, malondialdehyde, and 8-Hydroxydeoxyguanosine and higher expression of inflammatory mediators (IL-1β, IL-6, and IL-8), and AhR inducible genes (CYP1A1, and CYP1B1) than water extracts (p<0.05). Extracts of office dust presented greater suppression of superoxide dismutase and catalase activity than those of house dust. In addition, exposure to dust extracts activated NF-κB signal pathway except water extract of house dust. The results suggested that both water and organic soluble fractions of dust caused cytotoxicity, oxidative damage, inflammatory response, and activation of AhR inducible genes, with organic extracts having higher potential to induce adverse effects on primary HCE cells. The results based on primary HCE cells demonstrated the importance of reducing contaminants in indoor dust to reduce their adverse impacts on human eyes.

Mechanisms of housedust-induced toxicity in primary human corneal epithelial cells: Oxidative stress, proinflammatory response and mitochondrial dysfunction

Human cornea is highly susceptible to damage by dust. Continued daily exposure to housedust has been associated with increasing risks of corneal injury, however, the underlying mechanism has not been elucidated. In this study, a composite housedust sample was tested for its cytotoxicity on primary human corneal epithelial (PHCE) cells, which were exposed to dust at 5-320μg/100μL for 24h. PHCE cell viability showed a concentration-dependent toxic effect, attributing to elevated intracellular ROS. Moreover, when exposed at >20-80μg/100μL, dust-induced oxidative damage was evidenced by increased malondialdehyde and 8-hydroxy-2-deoxyguanosine (1.3-2.3-fold) and decreased antioxidative capacity (1.6-3.5-fold). Alteration of mRNA expression of antioxidant enzymes (SOD1, CAT, HO-1, TRXR1, GSTM1, GSTP1, and GPX1) and pro-inflammatory mediators (IL-1β, IL-6, IL-8, TNF-α, and MCP-1) were also observed. Furthermore, the mitochondrial transmembrane potential was dissipated from 9.2 to 82%. Our results suggested that dust-induced oxidative stress probably played a vital role in the cytotoxicity in PHCE cells, which may have contributed to dust-induced impairment of human cornea.

Single Exposure to near Roadway Particulate Matter Leads to Confined Inflammatory and Defense Responses: Possible Role of Metals

Inhalation of traffic-associated atmospheric particulate matter (PM2.5) is recognized as a significant health risk. In this study, we focused on a single ("subclinical response") exposure to water-soluble extracts from PM collected at a roadside site in a major European city to elucidate potential components that drive pulmonary inflammatory, oxidative, and defense mechanisms and their systemic impacts. Intratracheal instillation (IT) of the aqueous extracts induced a 24 h inflammatory response characterized by increased broncho-alveolar lavage fluid (BALF) cells and cytokines (IL-6 and TNF-α), increased reactive oxygen species production, but insignificant lipids and proteins oxidation adducts in mouse lungs. This local response was largely self-resolved by 48 h, suggesting that it could represent a subclinical response to everyday-level exposure. Removal of soluble metals by chelation markedly diminished the pulmonary PM-mediated response. An artificial metal solution (MS) recapitulated the PM extract response. The self-resolving nature of the response is associated with activating defense mechanisms (increased levels of catalase and glutathione peroxidase expression), observed with both PM extract and MS. In conclusion, metals present in PM collected near roadways are largely responsible for the observed transient local pulmonary inflammation and oxidative stress. Simultaneous activation of the antioxidant defense response may protect against oxidative damage.

Organic extracts from African dust storms stimulate oxidative stress and induce inflammatory responses in human lung cells through Nrf2 but not NF-κB

The health impact of the global African dust event (ADE) phenomenon in the Caribbean has been vaguely investigated. Heavy metals in ADE and non-ADE extracts were evaluated for the formation of reactive oxygen species (ROS) and antioxidant capacity by cells using, deferoxamine mesylate (DF) and N-acetyl-l-cysteine (NAC). Results show that ADE particulate matter 2.5 (PM2.5) induces ROS and stimulates oxidative stress. Pre-treatment with DF reduces ROS in ADE and Non-ADE extracts and in lung cells demonstrating that heavy metals are of utmost importance. Glutathione-S-transferase and Heme Oxygenase 1 mRNA levels are induced with ADE PM and reduced by DF and NAC. ADE extracts induced Nrf2 activity and IL-8 mRNA levels significantly more than Non-ADE. NF-κB activity was not detected in any sample. Trace elements and organic constituents in ADE PM2.5 enrich the local environment load, inducing ROS formation and activating antioxidant-signaling pathways increasing pro-inflammatory mediator expressions in lung cells.

Comparing acute toxicity of gunshot particles, from firing conventional and lead-free ammunition, in pulmonary epithelial cell cultures

Numerous studies demonstrated that the use of lead (Pb)-containing ammunition is associated with mainly chronic health problems and also is a burden on the environment and wildlife. Recently, a number of reports showed evidence of undesirable acute health effects related to the use of newly developed Pb-free small-caliber ammunition. In this study, particles from leaded and Pb-free ammunition were collected in liquid collection medium, in a highly controlled chamber, while firing a pistol (9 mm) or a rifle (7.62 × 51 mm). The emitted particles were typically smaller than 4 μm, with the great majority in even smaller size ranges, as shown by gravimetrical analysis and a multistage impactor. Chemical analysis revealed significant differences in content and concentration of several metals in the particles. After administration of the liquids to alveolar and bronchial in vitro cell systems, particles were taken up by the cells; the Pb-free particles displayed higher cytotoxicity (EC50 = 2 μg/cm(2)) than particles from Pb ammunition. High correlation factors (>0.9) were found between cell death and content of copper and zinc. Particles from both Pb-containing and Pb-free ammunition were able to induce oxidative stress and the proinflammatory marker interleukin (IL)-8 in both in vitro systems. These results support previous findings that indicate an association between gunshot emissions and metal fume fever. This study demonstrates the usefulness of combining chemical data with biological in vitro responses in assessing acute toxicological effects from emissions from firing both Pb and Pb-free ammunition.

Genetic damage in coal miners evaluated by buccal micronucleus cytome assay

During coal mining activities, large quantities of coal dust, ashes, polycyclic aromatic hydrocarbons and metals are released into the environment. This complex mixture presents one of the most important occupational hazards for health of workers. The aim of the present study was to evaluate the genetic damage together with the presence of inorganic elements, in an exposed workers population to coal mining residues of Guajira-Colombia. Thus, 100 exposed workers and 100 non-exposed control individuals were included in this study. To determine genetic damage we assessed the micronucleus (MN) frequencies and nuclear buds in buccal mucosa samples (BMCyt) assay, which were significantly higher in the exposed group than non-exposed control group. In addition, karyorrhectic and karyolytic cells were also significantly higher in the exposed group (cell death). No significant difference was observed between the exposed groups engaged in different mining activities. No correlation between age, alcohol consumption, time of service and MN assay data were found in this study. However, the content of inorganic elements in blood samples analyzed by a Particle-induced X-ray emission technique (PIXE) showed higher values of silicon (Si) and aluminum (Al) in the exposed group. In this study we discuss the possibility of DNA damage observed in the mine workers cells be a consequence of oxidative damage.