Inhalation of carbon black nanoparticles aggravates pulmonary inflammation in mice

The Impact of Acute Peri-operative Particulate Matter Exposure on Endoscopic Sinus Surgery Outcomes: A Preliminary Multi-site Investigation

BACKGROUND

Environmental exposures have been postulated to play an important role in the pathophysiology of chronic rhinosinusitis (CRS). Particulate matter (PM) is one of the most widely studied ambient air pollutants, but its peri-operative impact on CRS is unknown.

OBJECTIVE

To determine the effect of acute, peri-operative PM exposure on outcomes after endoscopic sinus surgery (ESS).

METHODS

Participants with CRS who self-selected ESS were prospectively enrolled. The 22-item SinoNasal Outcome Test (SNOT-22) and Medical Outcomes Study Questionnaire Short-Form 6-D (SF-6D) health utility values scores were recorded. Using residence zip codes, a secondary analysis of patient exposure to PM <2.5 μm and <10 μm (PM2.5 and PM10, respectively) was performed for the month of surgery utilizing data from Environmental Protection Agency air quality monitors. Spearman's correlation coefficients (ρ), 95% confidence intervals (CIs), and effect estimates (β) were used to determine the magnitudes of association. Simple, multivariate regression analysis was also completed.

RESULTS

One hundred and seven patients from four geographically unique institutions across the US were enrolled with a follow-up of 6 months. Patients with higher peri-operative PM2.5 exposure had less improvement in their SNOT-22 scores after ESS compared to those with less exposure using both univariate analysis (ρ = 0.26, 95% CI: 0.08, 0.43; P  =  .01) and after covariate adjustment with multivariate analysis (B  =  1.06, 95% CI: 0.001, 2.14, P  =  .05). Similar associations were not found with SF-6D outcomes or with PM10 as an exposure of interest. No significant correlations were found between peri-operative PM levels and Lund-Kennedy endoscopy scores post-operatively.

CONCLUSION

Preliminary data from this pilot study reveal that PM exposure at the time of ESS may negatively associate with post-operative improvement in sinonasal quality-of-life. Larger, population-based studies with more standardized PM exposure windows are needed to confirm the clinical significance of the present findings.

Melatonin prevents pulmonary fibrosis caused by PM2.5 exposure by targeting epithelial-mesenchymal transition

Pulmonary fibrosis is a lung disorder characterized by the accumulation of abnormal extracellular matrix, scar tissue formation, and tissue stiffness. Type II alveolar epithelial cells (AEII) play a critical role in repairing lung tissue after injury, and repeated injury to these cells is a key factor in the development of pulmonary fibrosis. Chronic exposure to PM2.5, a type of air pollution, has been shown to increase the incidence and severity of pulmonary fibrosis by enhancing the activation of EMT in lung epithelial cells. Melatonin, a hormone with antioxidant properties, has been shown to prevent EMT and reduce fibrosis in previous studies. However, the mechanism through which melatonin targets EMT to prevent pulmonary fibrosis caused by PM2.5 exposure has not been extensively discussed before. In this current study, we found that melatonin effectively prevented pulmonary fibrosis caused by prolonged exposure to PM2.5 by targeting EMT. The study demonstrated changes in cellular morphology and expression of EMT markers. Furthermore, the cell migratory potential induced by prolonged exposure to PM2.5 was greatly reduced by melatonin treatment. Finally, in vivo animal studies showed reduced EMT markers and improved pulmonary function. These findings suggest that melatonin has potential clinical use for the prevention of pulmonary fibrosis.

Pyrroloquinoline quinone ameliorates PM2.5-induced pulmonary fibrosis through targeting epithelial-mesenchymal transition

Pulmonary fibrosis is a lung disorder affecting the lungs that involves the overexpressed extracellular matrix, scarring and stiffening of tissue. The repair of lung tissue after injury relies heavily on Type II alveolar epithelial cells (AEII), and repeated damage to these cells is a crucial factor in the development of pulmonary fibrosis. Studies have demonstrated that chronic exposure to PM2.5, a form of air pollution, leads to an increase in the incidence and severity of pulmonary fibrosis by stimulation of epithelial-mesenchymal transition (EMT) in lung epithelial cells. Pyrroloquinoline quinone (PQQ) is a bioactive compound found naturally that exhibits potent anti-inflammatory and anti-oxidative properties. The mechanism by which PQQ prevents pulmonary fibrosis caused by exposure to PM2.5 through EMT has not been thoroughly discussed until now. In the current study, we discovered that PQQ successfully prevented PM2.5-induced pulmonary fibrosis by targeting EMT. The results indicated that PQQ was able to inhibit the expression of type I collagen, a well-known fibrosis marker, in AEII cells subjected to long-term PM2.5 exposure. We also found the alterations of cellular structure and EMT marker expression in AEII cells with PM2.5 incubation, which were reduced by PQQ treatment. Furthermore, prolonged exposure to PM2.5 considerably reduced cell migratory ability, but PQQ treatment helped in reducing it. In vivo animal experiments indicated that PQQ could reduce EMT markers and enhance pulmonary function. Overall, these results imply that PQQ might be useful in clinical settings to prevent pulmonary fibrosis.

MicroRNAs as Potential Biomarkers of Environmental Exposure to Polycyclic Aromatic Hydrocarbons and Their Link with Inflammation and Lung Cancer

Exposure to atmospheric air pollution containing volatile organic compounds such as polycyclic aromatic hydrocarbons (PAHs) has been shown to be a risk factor in the induction of lung inflammation and the initiation and progression of lung cancer. MicroRNAs (miRNAs) are small single-stranded non-coding RNA molecules of ~20-22 nucleotides that regulate different physiological processes, and their altered expression is implicated in various pathophysiological conditions. Recent studies have shown that the regulation of gene expression of miRNAs can be affected in diseases associated with outdoor air pollution, meaning they could also be useful as biomarkers of exposure to environmental pollution. In this article, we review the published evidence on miRNAs in relation to exposure to PAH pollution and discuss the possible mechanisms that may link these compounds with the expression of miRNAs.

PM2.5 promotes pulmonary fibrosis by mitochondrial dysfunction

Pulmonary fibrosis is known as an incurable lung disorder with irreversible progression of chronic injury, myofibroblast proliferation, extracellular matrix (ECM) accumulation, and tissue scarring. Atmospheric particulate matter 2.5 (PM_2.5 ) is implicated as a risk factor of several diseases, especially lung diseases such as pulmonary fibrosis. The molecular mechanism which participates PM_2.5 -induced pulmonary fibrosis in type II alveolar cells (AEII) has yet to be determined. Our results proved that short- and long-term exposure to PM_2.5 significantly stimulated epithelial-mesenchymal transition (EMT) activity in AEII cells, according to, changes in gene signature analyzed by RNA-seq and cell morphology. Furthermore, Gene Ontology (GO) enrichment analysis also suggested that mitochondrial dysfunction was related to progression of pulmonary fibrosis in AEII after PM_2.5 exposure. We observed a marked decline in mitochondria membrane potential (MMP), as well as fragmented mitochondria, in AEII cells exposed to PM_2.5 , which suggests that energy metabolism is suppressed after PM_2.5 exposure. We also confirmed that PM_2.5 exposure could influence the expression levels of Mfn1, Mfn2, and Drp1 in AEII. Pretreatment of mitochondrial fusion promoter M1 was able to reverse mitochondrial dysfunction as well as EMT in AEII. These data suggested the key role of mitochondrial fragmentation in AEII, which was induced by PM_2.5 exposure, and participated pathogenesis of pulmonary fibrosis. Finally, we investigated the response of lung tissue exposed to PM_2.5 in vivo. The data indicated that the lung tissue exposed to PM_2.5 obviously induced collagen accumulation. Moreover, IHC results revealed that PM_2.5 enhanced Drp1 expression but suppressed Mfn1 and Mfn2 expression in lung tissue. The current study provides novel insight of pulmonary fibrosis caused by PM_2.5 exposure.

The Physiological Effects of Air Pollution: Particulate Matter, Physiology and Disease

Nine out of 10 people breathe air that does not meet World Health Organization pollution limits. Air pollutants include gasses and particulate matter and collectively are responsible for ~8 million annual deaths. Particulate matter is the most dangerous form of air pollution, causing inflammatory and oxidative tissue damage. A deeper understanding of the physiological effects of particulate matter is needed for effective disease prevention and treatment. This review will summarize the impact of particulate matter on physiological systems, and where possible will refer to apposite epidemiological and toxicological studies. By discussing a broad cross-section of available data, we hope this review appeals to a wide readership and provides some insight on the impacts of particulate matter on human health.

Exposure to carbon black nanoparticles during pregnancy aggravates lipopolysaccharide-induced lung injury in offspring: an intergenerational effect

Carbon black nanoparticles (CBNPs) are one of the most frequently used nanoparticles. Exposure to CBNPs during pregnancy (PrE to CBNPs) can directly induce inflammation, lung injury, and genotoxicity in dams and results in abnormalities in offspring. However, whether exposure to CBNPs during pregnancy enhances the susceptibility of offspring to environmental stimuli remains unknown. To address this issue, in this study, we intranasally treated pregnant mice with mock or CBNPs from gestational day (GD) 9 to GD18, and F1 and F2 offspring were normally obtained. By intratracheal instillation of mice with lipopolysaccharide (LPS) to trigger a classic animal model for acute lung injury, we intriguingly found that after LPS treatment, F1 and F2 offspring after exposure during pregnancy to CBNPs both exhibited more pronounced lung injury symptoms, including more degenerative histopathological changes, vascular leakage, elevated MPO activity, and activation of inflammation-related signaling transduction, compared with F1 and F2 offspring in the mock group, suggesting PrE to CBNPs would aggravate LPS-induced lung injury in offspring, and this effect was intergenerational. We also observed that PrE to CBNPs upregulated the mRNA expression of DNA methyltransferases (Dnmt) 1/3a/3b and DNA hypermethylation in both F1 and F2 offspring, which might partially account for the intergenerational effect. Together, our study demonstrates for the first time that PrE to CBNPs can enhance sensitivity to LPS in both F1 and F2 offspring, and this intergenerational effect may be related to DNA hypermethylation caused by CBNPs.

Development of novel nanofibers targeted to smoke-injured lungs

Smoke inhalation injury is associated with significant mortality and current therapies remain supportive. The purpose of our study was to identify proteins upregulated in the lung after smoke inhalation injury and develop peptide amphiphile nanofibers that target these proteins. We hypothesize that nanofibers targeted to angiotensin-converting enzyme or receptor for advanced glycation end products will localize to smoke-injured lungs.

METHODS

Five targeting sequences were incorporated into peptide amphiphile monomers methodically to optimize nanofiber formation. Nanofiber formation was assessed by conventional transmission electron microscopy. Rats received 8 min of wood smoke. Levels of angiotensin-converting enzyme and receptor for advanced glycation end products were evaluated by immunofluorescence. Rats received the targeted nanofiber 23 h after injury via tail vein injection. Nanofiber localization was determined by fluorescence quantification.

RESULTS

Peptide amphiphile purity (>95%) and nanofiber formation were confirmed. Target proteins were increased in smoke inhalation versus sham (p < 0.001). After smoke inhalation and injection of targeted nanofibers, we found a 10-fold increase in angiotensin-converting enzyme-targeted nanofiber localization to lung (p < 0.001) versus sham with minimal localization of non-targeted nanofiber (p < 0.001).

CONCLUSIONS

We synthesized, characterized, and evaluated systemically delivered targeted nanofibers that localized to the site of smoke inhalation injury in vivo. Angiotensin-converting enzyme-targeted nanofibers serve as the foundation for developing a novel nanotherapeutic that treats smoke inhalation lung injury.

A new perspective on calmodulin-regulated calcium and ROS homeostasis upon carbon black nanoparticle exposure

Toxicological studies propose that exposure to carbon black nanoparticles induces organ injuries and inflammatory responses. Besides, current understanding of the molecular mechanisms implies that carbon black nanoparticles (CBNP) exposure induces the production of reactive oxygen species (ROS) causing inflammation, mitochondrial dysfunction or disturbance in calcium homeostasis. However, the precise mechanisms whereby CBNP exert these effects in the lung are still not fully understood. To gain insight into the possible mechanism of CBNP exerted toxicity, human alveolar epithelial cells (A549) were exposed to different concentrations of CBNP and for different timepoints. The reaction of the cells was monitored by the systematic use of cell-based measurements of calcium and ROS, in the presence and absence of calcium (Ca²⁺) pump inhibitors/chelators and antioxidants. Followed by an in-depth PCR analysis of 84 oxidative stress-related genes. The measurements revealed, as compared to the control, that exposure to CBNP nanoparticles leads to the generation of high ROS levels, as well as a disturbance in calcium homeostasis, which remained primarily unchanged even after 24 h of exposure. Nevertheless, in presence of antioxidants N-acetylcysteine (NAC) and Trolox, ROS formation was considerably reduced without affecting the intracellular calcium concentration. On the other hand, Ca²⁺ pump inhibitors/chelators, BAPTA (1,2-bis(o-amino phenoxy)ethane-N, N, N′, N′-tetraacetic acid) and verapamil not only decreased the Ca²⁺ overload, but also further decreased the ROS formation, indicating its role in CBNP-induced oxidative stress. Further, a PCR array analysis of A549 cells in presence and absence of the calmodulin (CaM) antagonist W7, indicated toward nine altered oxidative stress-related genes which further confirmed our cytotoxicity results. Obtained data suggested that CBNP exposure elevates calcium ion concentration, which further contributes to oxidative stress, via the calcium-binding protein CaM. Its inhibition with W7 leads to downregulation in gene expression of nine oxidative stress-related genes, which otherwise, as compared to control, show increased gene expression. The results of the study thus confirm that exposure of lung epithelial cells to CBNP leads to oxidative stress; however, the oxidative stress itself is a result of a disturbance in both calcium and ROS homeostasis, and should be considered while searching for a new strategy for prevention of CBNP-induced lung toxicity.

Carbon black nanoparticles induce HDAC6-mediated inflammatory responses in 16HBE cells

Long-term inhalation of carbon black nanoparticles (CBNPs) leads to pulmonary inflammatory diseases. Histone deacetylase 6 (HDAC6) has been identified as an important regulator in the development of inflammatory disorders. However, the direct involvement of HDAC6 in CBNPs-induced pulmonary inflammatory responses remains unclear. To explore whether HDAC6 participates in CBNPs-induced pulmonary inflammation, human bronchial epithelial cell line (16HBE cells) was transfected with HDAC6 small interference RNA (siRNA) and then exposed to CBNPs at concentrations of 0, 25, and 50 µg/ml for 24 h. Intracellular HDAC6 and intraflagellar transport protein 88 (IFT88) mRNA and protein were determined by real-time polymerase chain reaction and Western blot, respectively. The secretions of inflammatory cytokines including interleukin (IL)-8, tumor necrosis factor (TNF)-α, IL-6, and IL-1β were measured by enzyme-linked immunosorbent assay. CBNPs induced a significant increase in the expressions of IL-8 and IL-6, accompanied by a high level of intracellular HDAC6 mRNA when compared with a blank control group (p < 0.05). However, there were no significant changes in the levels of TNF-α secretion, intracellular HDAC6 and IFT88 protein induced by CBNPs (p > 0.05). The HDAC6 mRNA expression was significantly suppressed in HDAC6 siRNA-transfected cells (p < 0.05). The secretions of IL-8, TNF-α, and IL-6 were significantly less in HDAC6 siRNA-transfected cells than that in normal 16HBE cells with exposure to 25 or 50 µg/ml of CBNPs, but intracellular IFT88 mRNA expression was markedly increased in HDAC6 siRNA-transfected cells when compared with normal 16HBE cells exposed to 50 µg/ml of CBNPs (all p < 0.05). Downregulation of the HDAC6 gene inhibits CBNPs-induced inflammatory responses in bronchial epithelial cells, partially through regulating IFT88 expression. It is suggested that CBNPs may trigger inflammatory responses in bronchial epithelial cells by an HDAC6/IFT88-dependent pathway.

The Protective Effect of an Eye Wash Solution on the Ocular Surface Damage Induced by Airborne Carbon Black Exposure

PURPOSE

To investigate the effects of an eye wash solution on the ocular surface damage induced by airborne carbon black (CB) exposure.

METHODS

Sprague-Dawley rats were exposed to ambient CB for 5 days. During the 5 days, a commercial eye wash solution (Eyebon-W) was used for irrigation twice daily on CB-exposed rat eyes; normal saline was used as the vehicle control. Lactic dehydrogenase (LDH) activity and matrix metallopeptidase (MMP)-9, histamine, and lactoferrin levels were measured in tears. The expression of inflammatory cytokines in the anterior segment of the eyeball was measured by Western blot analysis.

RESULTS

The ocular surface staining scores, tear LDH activity, tear MMP-9, histamine, and lactoferrin concentrations, and the expression of interleukin-4 and interferon-γ in the eye were significantly increased in the CB group versus the normal control group. When compared with CB group, the Eyebon-W eye wash treatment significantly reversed these elevations induced by CB, including ocular staining scores, tear LDH activity, histamine and MMP-9 concentrations in the tear fluid, and the expression of interleukin-4 in the eye. On the other hand, saline irrigation only reduced the concentrations of histamine and MMP-9 in tear fluid and the expression of interferon-γ in the eye.

CONCLUSIONS

Both Eyebon-W eye wash treatment and saline irrigation reversed CB-induced ocular surface injury, but the efficacy of Eyebon-W was more significant than that of the saline solution when compared with CB group. The use of an eye wash solution seems to play a protective role for the ocular surface when exposed to airborne particulate matter.

A guide to crystal-related and nano- or microparticle-related tissue responses

Crystals and nano- and microparticles form inside the human body from intrinsic proteins, minerals, or metabolites or enter the body as particulate matter from occupational and environmental sources. Associated tissue injuries and diseases mostly develop from cellular responses to such crystal deposits and include inflammation, cell necrosis, granuloma formation, tissue fibrosis, and stone-related obstruction of excretory organs. But how do crystals and nano- and microparticles trigger these biological processes? Which pathomechanisms are identical across different particle types, sizes, and shapes? In addition, which mechanisms are specific to the atomic or molecular structure of crystals or to specific sizes or shapes? Do specific cellular or molecular mechanisms qualify as target for therapeutic interventions? Here, we provide a guide to approach this diverse and multidisciplinary research domain. We give an overview about the clinical spectrum of crystallopathies, about shared and specific pathomechanisms as a conceptual overview before digging deeper into the specialty field of interest.

N6-methyladenosine-dependent primary microRNA-126 processing activated PI3K-AKT-mTOR pathway drove the development of pulmonary fibrosis induced by nanoscale carbon black particles in rats

The pulmonary fibrosis could be caused by long-term inhalation of carbon black (CB) particles. Studies on the mechanisms of pulmonary fibrosis induced by CB are required to develop the stratagem of prevention and treatment on fibrosis. The RNA-binding protein DiGeorge syndrome critical region gene 8 (DGCR8)-dependent pri-miRNAs processing is regulated by N⁶-methyladenosine (m⁶A) modification, which targets the downstream signal pathway. However, its role in pulmonary fibrosis has not been known clearly. In the present study, rats inhaled CB at dose of 0, 5 or 30 mg/m³ for 28 days, 6 h/day, respectively. The rats inhaled CB at dose of 0 or 30 mg/m³ for 14 days, 28 days and 90 days, respectively. In vitro experiments, the normal human bronchial epithelial cell line (16HBE) was treated with CB (0, 50, 100 and 200 μg/mL) for 24 h. In vitro and vivo study, the levels of fibrosis indicators including α-SMA, vimentin, collagen-I and hydroxyproline in CB treatment groups statistically increased in dose- or time- dependent manners compared with the control. After CB treatment, PI3K-AKT-mTOR pathway was activated and regulated by miRNA-126. We found that both of m⁶A modifications of pri-miRNA-126 and its binding with DGCR8 were decreased after CB treatment, which resulted in the reduction of mature miRNA-126 accompanied by accumulation of unprocessed pri-miRNA-126. This work demonstrated that m⁶A modification of pri-miRNA-126 and its binding with DGCR8 decreases blocked miRNA-126 maturation, and then activated the PI3K/AKT/mTOR pathway, which drove the fibro genesis in the lung after CB exposure.

Toxicity of Zero- and One-Dimensional Carbon Nanomaterials

The zero (0-D) and one-dimensional (1-D) carbon nanomaterials have gained attention among researchers because they exhibit a larger surface area to volume ratio, and a smaller size. Furthermore, carbon is ubiquitously present in all living organisms. However, toxicity is a major concern while utilizing carbon nanomaterials for biomedical applications such as drug delivery, biosensing, and tissue regeneration. In the present review, we have summarized some of the recent findings of cellular and animal level toxicity studies of 0-D (carbon quantum dot, graphene quantum dot, nanodiamond, and carbon black) and 1-D (single-walled and multi-walled carbon nanotubes) carbon nanomaterials. The in vitro toxicity of carbon nanomaterials was exemplified in normal and cancer cell lines including fibroblasts, osteoblasts, macrophages, epithelial and endothelial cells of different sources. Similarly, the in vivo studies were illustrated in several animal species such as rats, mice, zebrafish, planktons and, guinea pigs, at various concentrations, route of administrations and exposure of nanoparticles. In addition, we have described the unique properties and commercial usage, as well as the similarities and differences among the nanoparticles. The aim of the current review is not only to signify the importance of studying the toxicity of 0-D and 1-D carbon nanomaterials, but also to emphasize the perspectives, future challenges and possible directions in the field.

Lysosomal dysfunction is associated with persistent lung injury in dams caused by pregnancy exposure to carbon black nanoparticles

AIMS

Carbon black nanoparticles (CBNPs) are widely used in industrial field. Sensitive stages such as pregnancy are assumed to be more susceptible to stimulus, however whether pregnancy exposure to CBNPs (PrE-to-CBNPs) would cause long-term toxic effects in dams and the underlying mechanisms remain poorly addressed. The present study is aimed to determine the long-term toxic effects of PrE-to-CBNPs in dams.

MATERIALS AND METHODS

The pregnant mice were randomly divided into control group, low (21 μg/animal), medium (103 μg/animal) and high (515 μg/animal) CBNPs-treated groups. From gestational day (GD) 9 to GD18, the pregnant mice were intranasal exposed. At 49 days after parturition, lung tissues and bronchoalveolar lavage fluid (BALF) were obtained. Weight change, lung histopathology, lung ultrastructural pathology, cell count in BALF, oxidative stress/inflammatory maker and autophagy/lysosome-related protein expression were determined.

KEY FINDINGS

PrE-to-CBNPs caused a dose-dependent persistent lung injury in mice even 49 days after parturition, including the deteriorative lung histopathological changes, elevation of oxidative stress marker Nrf-2, HO-1 and CHOP, infiltration of macrophage and increased mRNA expression of inflammatory cytokines in the lung tissues and elevation of cells in BALF. However, PrE-to-CBNPs did not induce significant neutrophil infiltration and fibrosis. Moreover, we found that CBNPs could deposit in the lysosomes and decrease cathepsin D (an important hydrolase in lysosome), which might be associated with the dysfunction of lysosome and autophagy.

SIGNIFICANCE

Our study demonstrated that PrE-to-CBNPs could result in long-term lung injury in dams, and lysosomal dysfunction was probably linked to this process.

Pregnancy exposure to carbon black nanoparticles exacerbates bleomycin-induced lung fibrosis in offspring via disrupting LKB1-AMPK-ULK1 axis-mediated autophagy

Accumulating evidence shows that carbon black nanoparticles (CBNPs) (one of the most used nanoparticles) can induce toxicity via induction of inflammation, oxidative stress and genotoxicity in vitro and in vivo, and epidemiological studies have indicated that the possible correlation between maternal immune activation and risk of developing neuropsychiatric disorder in the offspring. However, whether pregnancy exposure of CBNPs (Pr-CBNPs) enhances the susceptibility to bleomycin (BLM)-induced lung fibrosis in offspring is unknown. Herein, we demonstrated that Pr-CBNPs during gestational day 9-18 via intranasal administration could confer enhanced susceptibility to BLM-induced fibrotic response in offspring, including deteriorative lung pathologic changes and more collagen deposition. Intriguingly, we found that Pr-CBNPs repressed the activation of autophagy (an anti-fibrotic mechanism), which was moderately activated in offspring from mock group. Moreover, Pr-CBNPs was likely to disrupt the LKB1-AMPK-ULK1 axis (a key regulatory pathway for autophagy induction). In summary, this study provides the first evidence that pregnancy exposure to CBNPs can exacerbate BLM-induced lung fibrotic response in offspring probably through disruption of LKB1-AMPK-ULK1 axis-mediated autophagy.

The Protective Effect of a Topical Mucin Secretagogue on Ocular Surface Damage Induced by Airborne Carbon Black Exposure

Purpose

Exposure to airborne particulate matter can induce ocular surface damage and inflammation. We evaluated the effects of a topical mucin secretagogue on the mitigation of ocular surface damage induced by exposure to airborne carbon black (CB).

Methods

Sprague-Dawley rats were exposed to ambient CB for 2 hours twice daily for 5 days. Corneal staining score and tear lactic dehydrogenase (LDH) activity were measured to evaluate ocular surface damage. Serum immunoglobulin (Ig) G and IgE levels and the sizes of cervical lymph nodes were also measured. The expressions of interleukin (IL)-4, IL-17, and interferon (IFN)-γ were measured by Western blot analysis. Diquafosol tetrasodium was instilled six times a day for 5 days, and the extent of ocular surface damage was evaluated.

Results

After exposure to airborne CB, the median corneal staining score and LDH activity were significantly increased. Serum IgG and IgE levels and the sizes of cervical lymph nodes were also significantly increased. Additionally, the expression of IL-4 and IFN-γ was elevated in the anterior segment of the eyeball. Furthermore, the expression of IL-4, IL-17, and IFN-γ was elevated in the cervical lymph nodes. When exposed to airborne black carbon, topical diquafosol tetrasodium significantly increased tear MUC5AC concentration and decreased tear LDH activity.

Conclusions

Exposure to airborne CB induced ocular surface damage and increased proinflammatory cytokines in the eyes and cervical lymph nodes. Topical mucin secretagogues seem to have a protective effect on the ocular surface against exposure to airborne particulate matters.

PM2.5 induced pulmonary fibrosis in vivo and in vitro

Epidemiological studies have revealed positive correlation between particulate matter with an aerodynamic diameter of < 2.5 µm (PM_2.5) and pulmonary fibrosis (PF). As etiology and pathogenesis of PF have not been fully elucidated, this study was to investigate the potential mechanism by which PM_2.5 exposure adversely induced PF in vivo and in vitro. In the present study, 6-week-old C57/BL6J mice were intranasally administrated with PM_2.5 (100 μg/day) for 4 weeks. Micro-CT and hematoxylin-eosin (HE) staining analysis showed that lung inflammation and incipient fibrosis symptoms were induced after PM_2.5 exposure. The expression of Transforming growth factor-β1 (TGF-β1), α-Smooth muscle actin (α-SMA), and Collagen type I (COL1) in mice lung was increased. Upregulation of TGF-β1 in mice serum was also detected by ELISA after exposure to PM_2.5. Moreover, chronic PM_2.5 exposure on human bronchial epithelial cell line BEAS-2B cells led to activation of TGF-β1/SMAD3 pathway, TGF-β1 excretion and epithelial-mesenchymal transition (EMT), while PM_2.5 also triggered the activation of TGF-β1/SMAD3 pathway, TGF-β1 excretion as well as differentiation of human pulmonary fibroblast cell line HFL-1 cells, and TGF-β1 production in mouse macrophage cell line RAW264.7 cells. Furthermore, cell culture medium of PM_2.5-treated BEAS-2B and RAW264.7 cells could both activate TGF-β1/SMAD3 signaling, α-SMA and COL1 upregulation in HFL-1 cells. Therefore, we concluded that PM_2.5 could induce PF by targeting pulmonary epithelium, macrophages and fibroblasts, suggesting that PM_2.5 was a potent initiator of PF.

Pulmonary toxicities from a 90-day chronic inhalation study with carbon black nanoparticles in rats related to the systemical immune effects

Background: Recent years, there occurs heavy haze pollution in northern China during wintertime. The potential influence of airborne particulate matter (PM) on human health attracts great concern. The fuel-derived PM in the inhalable size range is dominated by aggregates of nanoparticles of Carbon black (CB). However, there are still lack of evidences especially regarding long-term exposure to explain the chronic effects of nanoscaled CB and the relative mechanism.

Purpose: The objective of this study was to identify the potential mechanism of chronic effects of nanoscale CB. The systemic toxicity, immune suppression or activity and local toxicity were evaluated.

Methods: 32 rats were divided into 2 groups: 30 mg/m3 CB exposure (nose only, 90 d, 6h/d) and control (clean air). Half of rats were scarified after exposure and another half of rats recovered for 14 days. Eight rats in each group were executed the lung function tests using a ventilated bias flow whole body plethysmograph (WBP). SDS-PAGE protocol was used to detect the deposition and retention of CB in lung of rats. HE staining was used to observe the changes of histopathology. Cell apoptosis was examined by TUNEL assay or flow cytometry. The levels of IL-6, IL-8, IL-17 and TNF-α in serum and lung tissue were evaluated with commercially available ELISA kit. The peripheral blood cell counts were detected by Auto 5-diff hematology analyzer.

Results: The lung burden of CB was 16 mg in lung of rats after a 90-day exposure by MPPD. Fourteen percentages of the amount of CB accumulated at the end of the exposure period was cleared from the lung during the 14 dys recovery period. The lung function was significantly decreased and could not recover after a short time recovery. The fibroblasts and granuloma formation were found in lung. The levels of apoptosis and DNA damages were significantly increased in lung cells after CB inhalation. The cytokines levels in lung but not in serum were significantly increased in CB exposure group. The cell counts of WBC, monocytes and neutrophils had 1.72, 3.13, and 2.73-fold increases after CB exposure, respectively. The percentages of CD4+ lymphocytes and the rates of CD4+/CD8+ were statistically increased after CB exposure. The stimulation indexes of the peripheral blood lymphocytes were significantly decreased after CB exposure. In the CB exposure group, the disrupted histomorphology of thymus and spleen were found as well as the early apoptotic thymocytes had a 2.36-fold increase.

Conclusion: CB induced the localized or direct toxicity and systemic immune toxicity. The direct and systemic immune responses had a combined effect on the lung damages caused by CB.

Autophagic flux blockage in alveolar epithelial cells is essential in silica nanoparticle-induced pulmonary fibrosis

Silica nanoparticles (SiNPs) have been reported to induce pulmonary fibrosis (PF) with an unknown mechanism. Recently, the activation of autophagy, a lysosome-dependent cell degradation pathway, by SiNPs has been identified in alveolar epithelial cells (AECs). However, the underlying mechanism and the relevance of SiNPs-induced autophagy to the development of PF remain elusive. Here, we report that autophagy dysfunction and subsequent apoptosis in AECs are involved in SiNPs-induced PF. SiNPs engulfed by AECs enhance autophagosome accumulation and apoptosis both in vivo and in vitro. Mechanically, SiNPs block autophagy flux through impairing lysosomal degradation via acidification inhibition. Lysosomal reacidification by cyclic-3',5'-adenosine monophosphate (cAMP) significantly enhances autophagic degradation and attenuate apoptosis. Importantly, enhancement of autophagic degradation by rapamycin protects AECs from apoptosis and attenuates SiNPs-induced PF in the mouse model. Altogether, our data demonstrate a repressive effect of SiNPs on lysosomal acidification, contributing to the decreased autophagic degradation in AECs, thus leading to apoptosis and subsequent PF. These findings may provide an improved understanding of SiNPs-induced PF and molecular targets to antagonize it.

Effects of technogenic pollutants on chicken embryos

Increasing interest in nanomaterials can be explained by their broad involvement in many fields of industry and medicine. It is known that carbon black and crysotile asbestos behave like nanosized objects. They are wide spread in environment and have close contact with living organisms. The aim of our study was to define the effects of carbon black and crysotile asbestos on structures of the developing organism.

We used chicken embryos as a model for our study. Total amount of 77 eggs was divided in three groups: one control and two experimental with introduced carbon black and asbestos respectively. Researched materials were injected in the yolk on the third day of incubation and tissues for study were taken during early, middle and late stages of incubation. Histological and electron microscopy methods were used.

Carbon black and asbestos introduction caused underdevelopment of embryos and vessels depletion in blood islands of the yolk sac. Asbestos slowed down angiogenesis. Soot particles caused integrity violation of vessels and led to extravasation. The manifestations of soot influence were damages to blood circulatory system and structural disorders on cellular level. Introduction of chrysotile asbestos mostly resulted in compensatoryadaptive reactions like increasing in hematopoiesis and transcytosis in endotheliocytes.

Unique pulmonary immunotoxicological effects of urban PM are not recapitulated solely by carbon black, diesel exhaust or coal fly ash

BACKGROUND

Exposure to particulate matter (PM) is increasing worldwide as a result of increased human activity, the rapid industrialization of developing countries, and effects of climate change. Adverse effects of PM on human health are well documented, and because PM exposure occurs mostly through the airways, PM has especially deleterious impact on the lungs.

OBJECTIVE

We investigated whether surrogate PM particles like carbon black (CB), diesel exhaust particle (DEP), coal fly ash (CFA) can recapitulate the allergic airway inflammatory response induced by urban particulate matter.

METHODS

We compared the pro-inflammatory potential of urban PM collected from New York (NYC) and Baltimore (Balt) with CB, DEP and CFA surrogate PM particles. Eight to ten weeks old BALB/cJ mice were exposed through the airways to particulate material, and markers of airway inflammation were determined. Specifically, we assessed cellular influx, mucus production, lung function, cytokine levels as well as immune cell profiling of the lungs.

RESULTS

Herein, we demonstrate that exposure to equivalent mass of stand-alone surrogate PM particles like CB, DEP and CFA, fails to induce significant airway inflammatory response seen after similar exposure to urban PMs. Specifically, we observe that PM collected from New York (NYC) and Baltimore city (Balt) triggers a mixed Th2/Th17 response accompanied by eosinophilic and neutrophilic influx, mucus production and airway hyperresponsiveness (AHR). Although the immune profile of NYC and Baltimore PMs are similar, they demonstrate considerable differences in their potency. Baltimore PM induced more robust airway inflammation, AHR, and Th2 cytokine production, possibly due to the greater metal content in Baltimore PM.

CONCLUSIONS

Urban particulate matter with its unique physiochemical properties and heterogeneous composition elicits a mixed Th2/Th17 allergic airway response that is not seen after similar exposures to surrogate PM particles.

Ozonized carbon black induces mitochondrial dysfunction and DNA damage

Black carbon and tropospheric ozone (O₃ ), which are major air pollutants in China, are hazardous to humans following inhalation. Black carbon can be oxidized by O₃ forming secondary particles of which the health effects are unknown. The present study utilized carbon black as a representative of black carbon to characterize the cytotoxicity induced by secondary particles in bronchial epithelial cells (16HBE) and C57BL/6J mice, and to investigate the implicated molecular pathways. Two types of carbon black including untreated carbon black (UCB) and ozonized carbon black (OCB) were presented. The effects of carbon black on cell viability, intracellular reactive oxygen species (ROS), oxidized/reduced glutathione ratio, mitochondrial membrane potential (MMP), intracellular ATP, and mitochondrial cytochrome c to cytoplasmic cytochrome c ratio were assessed in 16HBE. In addition, an alkaline comet assay and a cytokinesis-block micronucleus (CBMN) test with 16HBE cells in vitro and ELISA method for serum 8-hydroxy-2'-deoxyguanosine (8-OHdG) and a bone marrow micronucleus (BMN) test with C57BL/6J mice in vivo were performed to detect the genotoxicity. When compared with UCB exposed cells, OCB exposed cells had decreased cell viability, increased cell death rate, increased comet length and decreased MMP at 24 h exposure. UCB induced higher level of intracellular ROS than OCB from 4 to 23 h. No changes were observed for both OCB and UCB in serum 8-OHdG, intracellular ATP and mitochondrial cytochrome c to cytoplasmic cytochrome c ratio. The results of CBMN and BMN tests are negative. Intracellular ROS induced by OCB was lower than that of UCB. In summary, ozonization enhances the mitochondrial toxicity and genotoxicity of carbon black. Oxidative stress may not dominate in toxic effects of OCB. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 944-955, 2017.

Immunomodulation by gastrointestinal carbon black nanoparticle exposure in ovalbumin T cell receptor transgenic mice

Humans could become exposed to carbon black nanoparticles (CBNPs) in consumer products or an occupational setting. In rodent models, acute respiratory, subcutaneous, and direct immune cell exposure to CBNPs has been shown to enhance allergic sensitization to co-administered ovalbumin (OVA) protein from chicken egg. However, little is known about the effects of ingested CBNPs on immunological responses and oral tolerance to food antigens. We hypothesized that ingestion of CBNPs would enhance the development of food allergy to OVA. Allergy prone DO11.10 mice were orally exposed to CBNPs every second day for 2 weeks (total dose 10.8 (LOW) or 108 μg (HI)), with and without (±) co-administered OVA. Systemic immune parameters were measured at necropsy. Exposure to OVA resulted in significant increases in serum anti-OVA IgG1, anti-OVA IgM, and anti-OVA IgA antibodies relative to vehicle control. Immunophenotyping revealed a reduction in the number of OVA-specific CD4⁺T helper cells upon OVA ± CBNP^HI treatment in the spleen. Yet, secretion of the allergy-associated Th2 cytokines IL-4, IL-9, and IL-13 was greater in OVA_323-339 peptide-pulsed splenocytes from OVA + CBNP^HI-treated mice compared with control. Transcriptome analysis at necropsy of splenocytes from OVA + CBNP^HI dose mice compared with OVA mice revealed increases in the allergy associated genes Il4 and Stat6 and decreases in Csf3r and Retnlg. Although oral exposure to high-dose CBNPs did not impact OVA-specific antibody production relative to OVA, we did observe increased expression of genes and cytokines associated with allergy in peripheral splenocytes. This work suggests that CBNP gastrointestinal exposure may potentiate allergy pathways.

Aeroparticles, Composition, and Lung Diseases

Urban air pollution is a serious worldwide problem due to its impact on human health. In the past 60 years, growing evidence established a correlation between exposure to air pollutants and the developing of severe respiratory diseases. Recently particulate matter (PM) is drawing more public attention to various aspects including historical backgrounds, physicochemical characteristics, and its pathological role. Therefore, this review is focused on these aspects. The most famous air pollution disaster happened in London on December 1952; it has been calculated that more than 4,000 deaths occurred during this event. Air pollution is a complex mix of gases and particles. Gaseous pollutants disseminate deeply into the alveoli, allowing its diffusion through the blood–air barrier to several organs. Meanwhile, PM is a mix of solid or liquid particles suspended in the air. PM is deposited at different levels of the respiratory tract, depending on its size: coarse particles (PM₁₀) in upper airways and fine particles (PM_2.5) can be accumulated in the lung parenchyma, inducing several respiratory diseases. Additionally to size, the composition of PM has been associated with different toxicological outcomes on clinical and epidemiological, as well as in vivo and in vitro animal and human studies. PM can be constituted by organic, inorganic, and biological compounds. All these compounds are capable of modifying several biological activities, including alterations in cytokine production, coagulation factors balance, pulmonary function, respiratory symptoms, and cardiac function. It can also generate different modifications during its passage through the airways, like inflammatory cells recruitment, with the release of cytokines and reactive oxygen species (ROS). These inflammatory mediators can activate different pathways, such as MAP kinases, NF-κB, and Stat-1, or induce DNA adducts. All these alterations can mediate obstructive or restrictive respiratory diseases like asthma, COPD, pulmonary fibrosis, and even cancer. In 2013, outdoor air pollution was classified as Group 1 by IARC based on all research studies data about air pollution effects. Therefore, it is important to understand how PM composition can generate several pulmonary pathologies.

Cross regulation between hypoxia-inducible transcription factor-1α (HIF-1α) and transforming growth factor (TGF)-ß1 mediates nickel oxide nanoparticles (NiONPs)-induced pulmonary fibrosis

Numerous analyses including in vivo and in vitro experiments have demonstrated that inhalation exposure of NiONPs can result in pulmonary fibrosis. However, the potential mechanisms of this pathological process remain elusive. Here, we investigate the role of HIF-1α and TGF-ß1 in NiONPs-induced pulmonary fibrosis with a focus on the interplay of the above two proteins. In vivo, male Sprague&Dawley rats were exposed to NiONPs and pulmonary fibrosis was demonstrated using H&E staining and immunochemistry of αSMA. In vitro, NiONPs contributed to cell proliferation and increased expressions of collagen-1 and αSMA in human fetal lung fibroblasts. Both HIF-1α and TGF-ß1 were upregulated by NiONPs treatment. Inhibition of HIF-1α reduced TGF-ß1 expression and downregulation of TGF-ß1 reduced HIF-1α protein level. Mechanism investigation revealed that TGF-ß1 affects nuclear translocation activity of HIF-1α. Taken together, these finding provide evidence that HIF-1α and TGF-ß1 act in synergy to foster NiONPs-induced pulmonary fibrosis, and the cross talk between them is a pivotal mechanism of pulmonary fibrosis.

Nanotechnology in respiratory medicine

Like two sides of the same coin, nanotechnology can be both boon and bane for respiratory medicine. Nanomaterials open new ways in diagnostics and treatment of lung diseases. Nanoparticle based drug delivery systems can help against diseases such as lung cancer, tuberculosis, and pulmonary fibrosis. Moreover, nanoparticles can be loaded with DNA and act as vectors for gene therapy in diseases like cystic fibrosis. Even lung diagnostics with computer tomography (CT) or magnetic resonance imaging (MRI) profits from new nanoparticle based contrast agents. However, the risks of nanotechnology also have to be taken into consideration as engineered nanomaterials resemble natural fine dusts and fibers, which are known to be harmful for the respiratory system in many cases. Recent studies have shown that nanoparticles in the respiratory tract can influence the immune system, can create oxidative stress and even cause genotoxicity. Another important aspect to assess the safety of nanotechnology based products is the absorption of nanoparticles. It was demonstrated that the amount of pulmonary nanoparticle uptake not only depends on physical and chemical nanoparticle characteristics but also on the health status of the organism. The huge diversity in nanotechnology could revolutionize medicine but makes safety assessment a challenging task.