The acute airway inflammation induced by PM2.5 exposure and the treatment of essential oils in Balb/c mice

Inhibitory functions of cardamonin against particulate matter-induced lung injury through TLR2,4-mTOR-autophagy pathways

Particulate matter with an aerodynamic diameter equal to or less than 2.5 μm (PM_2.5) is a form of air pollutant that causes significant lung damage when inhaled. Cardamonin, a flavone found in Alpinia katsumadai Heyata seeds, has been reported to have anti-inflammatory and anticoagulative activity. The aim of this study was to determine the protective effects of cardamonin on PM_2.5-induced lung injury. Mice were treated with cardamonin via tail-vein injection 30 min after the intratracheal instillation of PM_2.5. The results showed that cardamonin markedly reduced the pathological lung injury, lung wet/dry weight ratio, and hyperpermeability caused by PM_2.5. Cardamonin also significantly inhibited PM_2.5-induced myeloperoxidase (MPO) activity in lung tissue, decreased the levels of PM_2.5-induced inflammatory cytokines and effectively attenuated PM_2.5-induced increases in the number of lymphocytes in the bronchoalveolar lavage fluid (BALF). And, cardamonin increased the phosphorylation of mammalian target of rapamycin (mTOR) and dramatically suppressed the PM_2.5-stimulated expression of toll-like receptor 2 and 4 (TLR 2,4), MyD88, and the autophagy-related proteins LC3 II and Beclin 1. In conclusion, these findings indicate that cardamonin has a critical anti-inflammatory effect due to its ability to regulate both the TLR2,4-MyD88 and mTOR-autophagy pathways and may thus be a potential therapeutic agent against PM_2.5-induced lung injury.

Potential hazardous effects of printing room PM2.5 exposure include promotion of lung inflammation and subsequent injury

There have been few studies investigating the potential effects of indoor sources of particulate matter on human health. In this study, the effect of different concentrations of fine particulate matter (PM_2.5) collected from a printing room on lung health was examined using cultured cells and a mouse model. Further, the mechanism of lung injury was examined. The results indicated that PM_2.5 significantly enhanced malondialdehyde activity (P<0.05), decreased superoxide dismutase activity (P<0.05), upregulated the expression of pro-inflammatory factors including interleukin (IL)-1β, tumor necrosis factor-, IL-6 and downregulated the expression of the inflammatory factor IL-2 (P<0.05). Western blot analysis indicated that PM_2.5 significantly enhanced expression of phosphorylated (p)-ERK relative to total ERK, cyclooxygenase-2, p-anti-nuclear-factor-κB (p-NF-κB) relative to NF-κB, transforming growth factor-β1 and Bax relative to Bcl-2 in inflammation (P<0.05), fibrosis and apoptosis signaling pathways. Furthermore, the results revealed that exposure was associated with an increased abundance of pathogens including Burkholderiales, Coriobacteriia, and Betaproteobacteria in in the lungs. In conclusion, exposure to PM_2.5 from a printing room significantly increased inflammation, fibrosis, apoptosis and the abundance of pathogenic bacteria, indicating that exposure is potential threat to individuals who spend a significant amount of time in printing rooms.

Ambient PM Toxicity Is Correlated with Expression Levels of Specific MicroRNAs

Uncertainties regarding optimized air pollution control remain as the underlying mechanisms of city-specific ambient particulate matter (PM)-induced health effects are unknown. Here, water-soluble extracts of PMs collected from four global cities via automobile air-conditioning filters were consecutively injected three times by an amount of 1, 2, and 2 mg into the blood circulation of Wistar rats after filtration by a 0.45 μm pore size membrane. Acute health effects, such as immune and inflammatory responses and hemorrhage in alveoli, were observed right after the PM extraction injection. Significant differences between cities in biomarker tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) levels were detected following the second and third PM injections. Rats' inflammatory responses varied substantially with the injections of city-specific PMs. Repeated PM extract exposure rendered the rats more vulnerable to subsequent challenges, and downregulation of certain microRNAs was observed in rats. Among the studied miRNAs, miR-125b, and miR-21 were most sensitive to the PM exposure, exhibiting a negative dose-response-type relationship with a source-specific PM (oxidative potential) toxicity (r² = 0.63 and 0.57; p-values < 0.05). The results indicated that city-specific PMs could induce different health effects by selectively regulating different miRNAs, and that certain microRNAs, e.g., miR-125b and miR-21, may be externally mediated to neutralize PM-related health damages.

Respiratory exposure to PM2.5 soluble extract disrupts mucosal barrier function and promotes the development of experimental asthma

BACKGROUND

Air pollutants are important factors that contribute to the development and exacerbation of asthma, but experimental evidence still needs to be collected and the mechanisms still need to be addressed. In this study, we aimed to assess the association between PM2.5 exposure and asthma development. The effects of PM2.5 exposure on the barrier functions of airway epithelial cells were also determined.

METHODS

PM2.5 was collected from Nanjing, China, and its soluble extract was prepared. Human lung epithelial cells (BEAS-2B) were treated with different concentrations of soluble PM2.5 extract, and cell viability was detected by FACS using Annexin V-FITC staining. PM2.5-induced oxidative stress and inflammatory events were assessed by DCF-DA staining and qPCR. PM2.5-induced dysfunction of the airway epithelial barrier was assessed by measuring the expression of tight junction molecules. In vivo, BALB/c mice were treated with OVA in the presence or absence of PM2.5 solution, followed by exposure to OVA aerosols. Allergy-induced airway inflammation and lung injury were assessed by histopathological analyses.

RESULTS

Soluble PM2.5 extract exposure in vitro decreased the viability and increased apoptosis of airway epithelial cells. Soluble PM2.5 extract induced oxidative stress and enhanced pro-inflammatory factor expression by activating the NF-κB and MAPK signalling pathways, which were accompanied by reduced airway barrier function. The in vivo data demonstrated that PM2.5 exposure increased the effects of allergy sensitization after respiratory exposure to allergens, which led to the development of asthma.

CONCLUSION

This study suggests that exposure to soluble PM2.5 extract contributes to airway barrier dysfunction. The soluble mediators generated by airway epithelial cells in response to PM2.5 exposure orchestrate the breaking of inhalational tolerance and sensitization to allergic antigens, leading to the exacerbated development of asthma.

Ambient particulate matter triggers dysfunction of subcellular structures and endothelial cell apoptosis through disruption of redox equilibrium and calcium homeostasis

Ambient particulate matter (APM) is becoming a global environmental problem that seriously jeopardizes public health. Previous evidence hinted that APM correlates to cardiovascular diseases. As a potential target, equilibrium of endothelial cell is a prerequisite for vascular health which could be vulnerably attacked by particles, but the specific mechanisms whereby APM damages endothelial cells have not been fully elucidated. In the current study, based on two classical mechanisms of oxidative stress and intracellular calcium overload, we aimed to explore their roles in APM-induced endothelial cell apoptosis from the perspective of subcellular levels, including endoplasmic reticulum (ER) stress and mitochondrial dysfunction. As a result, PM SRM1648a results in oxidative stress and calcium overload in EA.hy926 cells. Additionally, ERs and mitochondria could be severely disturbed by particles in morphology and function, characterized by swelling ERs, mitochondrial fission and disappearance of cristae, coupled with ER damage, mtROS overproduction and significant reduction in mitochondrial membrane potential (MMP). Adverse effects on these organelles are the prime culprits of following apoptosis in endothelial cells. Fortunately, additional antioxidants and calcium inhibitors could mitigate cellular lesion through improvement of subcellular function. Intriguingly, antioxidants relieve cell stress via both mitochondrial and ER stress-mediated pathways, whereas the role of calcium modulators in cell apoptosis is independent of the mitochondrial pathway but could be explained by amelioration of ER stress. In conclusion, our data basically revealed that internalized PM SRM1648a triggers oxidative stress and calcium influx in EA.hy926 endothelial cells, followed by multiple subcellular damage and eventually contributes to cell death, during which antioxidants and calcium inhibitors confer protective effects.

Oxidative stress activates the TRPM2-Ca2+-NLRP3 axis to promote PM2.5-induced lung injury of mice

PM_2.5, a main particulate air pollutant, poses a serious hazard to human health. The exposure to PM_2.5 increases mortality and morbidity of many respiratory diseases such as asthma, chronic obstructive pulmonary diseases and even lung cancer. The contribution of reactive oxygen species (ROS) in the PM_2.5-induced acute lung injury process was confirmed in our previous research, but the molecular mechanism based for it remains unclarified. In this research, ROS-induced lung injury after exposure to PM_2.5 was explored in vivo and in vitro. The in vivo study indicated that N-acetyl-L-cysteine (NAC) could attenuate the accumulation of inflammatory cells, the thickening of alveolar wall and the degree of lung injury. Furthermore, we found ROS could regulate the intracellular Ca²⁺ level, expression of the Transient Receptor Potential Melastatin 2 (TRPM2), NLRP3 and its downstream inflammatory factors in vivo. In vitro experiments with A549 cells and primary type II alveolar epithelium cells (SD cells) showed that ROS induced by PM_2.5 exposure could mediate intracellular Ca²⁺ mobilization via TRPM2, with a subsequent activation of NLRP3. In our present study, we demonstrated the contribution of the ROS-TRPM2-Ca²⁺-NLRP3 pathway in PM_2.5-induced acute lung injury and offered a potential therapeutical target valid for related pathology.

Organ-on-a-Chip: Opportunities for Assessing the Toxicity of Particulate Matter

Recent developments in epidemiology have confirmed that airborne particulates are directly associated with respiratory pathology and mortality. Although clinical studies have yielded evidence of the effects of many types of fine particulates on human health, it still does not have a complete understanding of how physiological reactions are caused nor to the changes and damages associated with cellular and molecular mechanisms. Currently, most health assessment studies of particulate matter (PM) are conducted through cell culture or animal experiments. The results of such experiments often do not correlate with clinical findings or actual human reactions, and they also cause difficulty when investigating the causes of air pollution and associated human health hazards, the analysis of biomarkers, and the development of future pollution control strategies. Microfluidic-based cell culture technology has considerable potential to expand the capabilities of conventional cell culture by providing high-precision measurement, considerably increasing the potential for the parallelization of cellular assays, ensuring inexpensive automation, and improving the response of the overall cell culture in a more physiologically relevant context. This review paper focuses on integrating the important respiratory health problems caused by air pollution today, as well as the development and application of biomimetic organ-on-a-chip technology. This more precise experimental model is expected to accelerate studies elucidating the effect of PM on the human body and to reveal new opportunities for breakthroughs in disease research and drug development.

Particulate matter exposure aggravates osteoarthritis severity

Several diseases have been linked to particulate matter (PM) exposure. Outdoor activities, such as road running or jogging, are popular aerobic exercises due to few participatory limitations. Osteoarthritis (OA) is a progressive degenerative joint disease, usually observed at age 40, and not noticed before pain or diagnosis. Although exercise has health benefits, it is unclear whether outdoor jogging in higher PM (standard reference material 1649b, SRM 1649b) concentration environments could affect OA development or severity. Hence, a PM exposure monosodium iodoacetate (MIA)-induced OA animal jogged model was established for investigation. Results showed that high doses of PM (5 mg) significantly increased pro-inflammatory factors such as tumor necrosis factor α (TNF-α), interleukin (IL)-1β, and IL-6, and M1 macrophages in the lung region, also obtained in systemic IL-6 and TNF-α expressions in this MIA-OA rat model. Moreover, levels of osteocalcin, cartilage oligomeric matrix protein (COMP), and N-telopeptides of type I collagen were especially influenced in MIA+PM groups. Morphological and structural changes of the knee joint were detected by micro-computed tomography images (micro-CT) and immunohistochemistry. MIA + PM rats exhibited severe bone density decrease, cartilage wear, and structure damages, accompanied by lower levels of physical activity, than the sham group and groups receiving MIA or PM alone. The findings suggest that the severity of OA could be promoted by PM exposure with a PM concentration effect via systemic inflammatory mechanisms. To the best of our knowledge, this is the first study to provide direct effects of PM exposure on OA severity.

Metabolic linkages between indoor negative air ions, particulate matter and cardiorespiratory function: A randomized, double-blind crossover study among children

BACKGROUND

Ionization air purifiers, which purify particulate matter (PM) by producing vast number of negative air ions (NAI), are widely used. Recent study implied that ionization air purification could bring respiratory benefits but deterioration of heart rate variability (HRV). However, its underlying molecular mechanisms remain unclear.

OBJECTIVES

To explore the molecular linkages between indoor NAI, decreased PM and the cardiorespiratory effect after purification.

METHODS

Urine samples were collected from 44 healthy children three times of each study period (real and sham purification) in an existing randomized, double-blind crossover study. Ultra-high performance liquid chromatography/mass spectrometry was conducted in metabolomics analysis, the associations between indoor NAI, decreased PM and the cardiorespiratory function were investigated via the meet-in-metabolite approach (MIMA) based on statistical and metabolic pathway analysis. Mixed-effect models were used to establish associations between exposure, health parameters and metabolites.

RESULTS

Twenty-eight and fourteen metabolites were identified with significant correlations to NAI and PM, respectively. Besides, eight and eighteen metabolites were separately associated with respiratory function and HRV. The increased NAI and decreased PM improved respiratory function mainly with eight pathways, promoting energy production, anti-inflammation and anti-oxidation capacity. Decreased PM ameliorated HRV with six main pathways, increasing energy production and anti-inflammation capacity while increased NAI deteriorated HRV with five main pathways, lowering energy generation and anti-oxidation capacity.

CONCLUSIONS

Increased NAI and decreased PM ameliorated respiratory function by increasing energy production, improving anti-inflammation and anti-oxidation capacity. Decreased PM improved cardiac autonomic function by increasing energy production and anti-inflammation capacity, while these benefits were overcast by massive NAI via lowering energy generation and anti-oxidation capacity with different metabolic pathways.

Preventive effect of ursolic acid derivative on particulate matter 2.5-induced chronic obstructive pulmonary disease involves suppression of lung inflammation

Respiratory diseases like chronic obstructive pulmonary disease (COPD) are associated with the presence of particulate matter 2.5 (PM2.5) in the air. In the present study, the effect of synthesized ursolic acid derivatives on mice model of PM2.5-induced COPD was investigated in vivo. The mice model of COPD was established by the administration of 25 μL of PM2.5 suspension through intranasal route daily for 1 week. The levels of oxidative stress markers and inflammatory cytokines like tumor necrosis factors-α and interleukin-6 in the mice bronchoalveolar fluids increased markedly on administration with PM2.5. However, treatment with ursolic acid derivative caused a significant suppression in PM2.5-induced increase in oxidative stress markers and inflammatory cytokines in dose-dependent manner. Hematoxylin and eosin staining showed excessive inflammatory cell infiltration in pulmonary tissues in mice with COPD. The inflammatory cell infiltration was inhibited on treatment of the mice with ursolic acid derivative. The ursolic acid derivative treatment increased level of superoxide dismutase in mice with COPD. The lung injury induced by PM2.5 in mice was also prevented on treatment with ursolic acid derivative. Thus, ursolic acid derivative inhibits pulmonary tissues damage in mice through suppression of inflammatory cytokine and oxidative enzymes. Therefore, ursolic acid derivative can be of therapeutic importance for treatment of PM2.5-induced COPD.

Inhibitory functions of maslinic acid on particulate matter-induced lung injury through TLR4-mTOR-autophagy pathways

Particulate matter (PM), the collection of all liquid and solid particles suspended in air, includes both organic and inorganic particles, many of which are health-hazards. PM particles with a diameter equal to or less than 2.5 μm (PM_2.5) is a form of air pollutant that causes significant lung damage when inhaled. Maslinic acid (MA) prevents oxidative stress and pro-inflammatory cytokine generation, but there is little information available regarding its role in PM-induced lung injury. Therefore, the purpose of this study was to determine the protective activity of MA against PM_2.5-induced lung injury. The mice were divided into seven groups (n = 10 each): a mock control group, an MA control (0.8 mg/kg mouse body weight) group, an opted PM_2.5 produced from diesel (10 mg/kg mouse body weight) group, a diesel PM_2.5+MA (0.2, 0.4, 0.6, and 0.8 mg/kg mouse body weight) groups. Mice were treated with MA via tail-vein injection 30 min after the intratracheal instillation of a diesel PM_2.5. Changes in the wet/dry weight ratio of the lung tissue, total protein/total cell and lymphocyte counts, inflammatory cytokines in the bronchoalveolar lavage fluid (BALF), vascular permeability, and histology were monitored in diesel PM_2.5-treated mice. The results showed that MA reduced pathological lung injury, the wet/dry weight ratio of the lung tissue, and hyperpermeability caused by diesel PM_2.5. MA also inhibited diesel PM_2.5-induced myeloperoxidase (MPO) activity in the lung tissue, decreased the levels of diesel PM_2.5-induced inflammatory cytokines, including tumor necrosis factor (TNF)-α and interleukin (IL)-1β, reduced nitric oxide (NO) and total protein in the BALF, and effectively attenuated diesel PM_2.5-induced increases in the number of lymphocytes in the BALF. In addition, MA increased the protein phosphorylation of the mammalian target of rapamycin (mTOR) and dramatically suppressed diesel PM_2.5-stimulated expression of toll-like receptor 4 (TLR4), MyD88, and the autophagy-related proteins LC3 II and Beclin 1. In conclusion, these findings indicate that MA has a critical anti-inflammatory effect due to its ability to regulate both the TLR4-MyD88 and mTOR-autophagy pathways and may thus be a potential therapeutic agent against diesel PM_2.5-induced lung injury.

PM2.5 induces autophagy and apoptosis through endoplasmic reticulum stress in human endothelial cells

Endothelial cells integrally form a crucial interface that maintains homeostasis of the cardiovascular system. As a vulnerable target of PM2.5, the underlying mechanisms of endothelial cell damage have yet to be fully elucidated. In the current study, two types of cell death, including autophagy and apoptosis, and an important organelle of the endoplasmic reticulum (ER) were focalized following PM2.5 exposure. As a result, the internalization of PM2.5 has the ability to induce excess ER stress, which is a crucial step for further autophagy and apoptosis in human endothelial cells, as confirmed by the pre-treatment with the inhibitor of ER stress (4-PBA) which effectively mitigates the apoptosis rate and LC3II expression. Intriguingly, crosstalk between ER stress and autophagy demonstrated that ER stress is probably involved in autophagic events, whereas autophagy has no significant effect on ER stress but confer a protective role against PM2.5-induced endothelial cell apoptosis. Moreover, PM2.5 results in blockage of autophagic flux (failed fusion between autophagosomes and lysosomes), which is detrimental to endothelial cell survival. In conclusion, our findings provide a valuable insight into the relation between autophagy and apoptosis under PM2.5-induced ER stress conditions, where the interplay between them ultimately determines cell fate.

Impact of long-term exposure wildfire smog on respiratory health outcomes

Background: Air pollution is a global problem and also linked to respiratory diseases. Wildfire smog is a major cause of air pollution in the upper northern area of Thailand. Thus, in the current study, we examined whether long-term exposure to wildfire smog induces lung function changes in a population from the upper northern area of Thailand.Methods: The lung function of 115 participants with long-term exposure smog was determined using peak flow meter.Results: Long-term smoke exposure participants decreased FEV₁ (forced expiratory volume in 1 second)/FVC (forced vital capacity) ratio (56.49 ± 23.88 in males and 56.29 ± 28.23 in females) compared with general Thai population. Moreover, the reduction of FVC, FEV₁, and peak expiratory flow rate (PEFR) values also showed in both male and female subjects. These results suggest that long-term smoke exposure induces obstructive lung abnormality. Moreover, itchy/watery nose, cough, phlegm, and chest pain also reported in these subjects.Conclusion: Wildfire smog could be induced respiratory pathway inflammation and easily collapsible respiratory airways.

Therapeutic effects of shibashin misena® against fine-dust-induced pulmonary disorders in mice

INTRODUCTION

In recent decades, fine-dust particulate matter (FM) has become a potential health hazard, causing various pathological respiratory disorders around the world. Inflammation induced by FM is regarded as a major cause of respiratory disorder in humans. The purpose of this study was to evaluate the therapeutic efficacy of Shibashin Misena®, a functional food composed of various bioactive ingredients, on FM-induced respiratory disorders in mice.

MATERIALS AND METHODS

Briefly, 40 mice were divided equally into four groups: normal controls (NC); FM-induced control group (FC); FM group treated with Shibashin Misena® 0.1 mL/head/day (FM0.1); FM group treated with Shibashin Misena® 0.2 mL/head/day (FM0.2).

RESULTS

FM significantly induced TNF-α, IL-17A, IL-1β, and TGF-β in bronchoalveolar lavage fluid (BALF) collected from the FM mice. Compared with FC, Shibashin Misena® decreased TNF-α, IL-17A, and IL-1β levels in BALF, and histopathologic evaluations revealed that Shibashin Misena® treatment significantly reduced inflammatory-cell infiltration and fibrosis related collagen deposition in lung tissue.

CONCLUSION

This study demonstrated that Shibashin Misena® decreased FM-induced inflammation and fibrosis in lung tissue. Thus, Shibashin Misena® could be an effective supplement to prevent or improve FM-induced pulmonary disorders.

Quantitative evaluation of lung injury caused by PM2.5 using hyperpolarized gas magnetic resonance

PURPOSE

To demonstrate the feasibility of ¹²⁹ Xe MR in evaluating the pulmonary physiological changes caused by PM_2.5 in animal models.

METHODS

Six rats were treated with PM_2.5 solution (16.2 mg/kg) by intratracheal instillation twice a week for 4 weeks, and another six rats treated with normal saline served as the control cohort. Pulmonary function tests, hyperpolarized ¹²⁹ Xe multi-b diffusion-weighted imaging, and chemical shift saturation recovery MR spectroscopy were performed on all rats, and the pulmonary structure and functional parameters were obtained from hyperpolarized ¹²⁹ Xe MR data. Additionally, histological analysis was performed on all rats to evaluate alveolar septal thickness. Statistical analysis of all the obtained parameters was performed using unpaired 2-tailed t tests.

RESULTS

Compared with the control group, the measured exchange time constant increased from 11.74 ± 2.39 to 14.00 ± 2.84 ms (P < .05), and the septal wall thickness increased from 6.17 ± 0.48 to 6.74 ± 0.52 μm (P < .05) in the PM_2.5 cohort by ¹²⁹ Xe MR spectroscopy, which correlated well with that obtained using quantitative histology (increased from 5.52 ± 0.32 to 6.20 ± 0.36 μm). Additionally, the mean TP/GAS ratio increased from 0.828 ± 0.115 to 1.019 ± 0.140 in the PM_2.5 cohort (P = .021).

CONCLUSIONS

Hyperpolarized ¹²⁹ Xe MR could quantify the changes in gas exchange physiology caused by PM_2.5 , indicating that the technique has the potential to be a useful tool for evaluation of pulmonary injury caused by air pollution in the future.

Respiratory Health Effects of Exposure to Ambient Particulate Matter and Bioaerosols

Researchers have been studying the respiratory health effects of ambient air pollution for more than 70 years. While air pollution as a whole can include gaseous, solid, and liquid constituents, this article focuses only on the solid and liquid fractions, termed particulate matter (PM). Although PM may contain anthropogenic, geogenic, and/or biogenic fractions, in this article, particles that originate from microbial, fungal, animal, or plant sources are distinguished from PM as bioaerosols. Many advances have been made toward understanding which particle and exposure characteristics most influence deposition and clearance processes in the respiratory tract. These characteristics include particle size, shape, charge, and composition as well as the exposure concentration and dose rate. Exposure to particles has been directly associated with the exacerbation and, under certain circumstances, onset of respiratory disease. The circumstances of exposure leading to disease are dependent on stressors such as human activity level and changing particle composition in the environment. Historically, researchers assumed that bioaerosols were too large to be inhaled into the deep lung, and thus, not applicable for study in conjunction with PM2.5 (the 2.5-μm and below size fraction that can reach the deep lung); however, this concept is beginning to be challenged. While there is extensive research on the health effects of PM and bioaerosols independent of each other, only limited work has been performed on their coexposure. Studying these two particle types as dual stressors to the respiratory system may aid in more thoroughly understanding the etiology of respiratory injury and disease. © 2020 American Physiological Society. Compr Physiol 10:1-20, 2020.

Effects of Total Flavonoids from Exocarpium Citri Grandis on Air Pollution Particle-Induced Pulmonary Inflammation and Oxidative Stress in Mice

Exocarpium Citri Grandis (ECG) is a famous traditional Chinese medicine, which has been commonly used to alleviate cough and phlegm for more than several hundred years, and total flavonoids are the main effective components of this medicine. This study investigated the effects of total flavonoids from ECG (TFECG) on pulmonary inflammation and oxidative stress induced by PM_2.5 in mice. Model mice received an intratracheal instillation of PM_2.5 (10 mg/mL) once at day 0. Bronchoalveolar lavage fluid (BALF) was collected after 72 hr to measure the total number of white blood cell (WBC), neutrophils (NEUT), lymphocytes (LYMPH), and monocytes (MONO). The levels of tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), interleukin-6 (IL-6), and interleukin-18 (IL-18) in BALF were quantified by using enzyme-linked immunosorbent assay kits. Lung tissues were used to determine the contents of total protein (TP), malondialdehyde (MDA), nitric oxide (NO), reduced glutathione (GSH), oxidized glutathione (GSSG) and the activities of superoxide dismutase (SOD), lactate dehydrogenase (LDH), Glutathione Peroxidase (GSH-Px), and inducible nitric oxide synthase (iNOS). We found that TFECG significantly inhibited PM_2.5 -stimulated overproduction of TNF-α, IL-1β, IL-6, and IL-18 and increased the numbers of WBC, NEUT, LYMPH, and MONO in BALF. TFECG observably relieved the PM_2.5 -induced increases in the contents of TP, MDA, and NO, and the activities of LDH and iNOS. TFECG also alleviated PM_2.5 -induced decreases in the activities of iNOS and GSH-Px as well as GSH/GSSG ratio. The results indicate that TFECG has anti-inflammatory and antioxidant activities, which may potentially contribute to the treatment of PM_2.5 -induced lung injury. PRACTICAL APPLICATION: Exocarpium Citri Grandis (ECG) is rich in flavonoids, which are beneficial to improve anti-inflammation and antioxidant capacity. We proved that total flavonoids of ECG had a positive therapeutic effect on PM_2.5 -induced lung injury, which expands the potential applications of ECG in the dietary supplement industries.

Resveratrol alleviates chronic "real-world" ambient particulate matter-induced lung inflammation and fibrosis by inhibiting NLRP3 inflammasome activation in mice

BACKGROUND

Inhalation of fine particulate matter (PM_2.5) induces the occurrence of lung inflammation and fibrosis, but its molecular mechanism remains unclear. Resveratrol (RES) is known to have anti-inflammatory properties in many pulmonary diseases. Here, we aimed to investigate the effect of long-term "real-world" ambient PM exposure on lung inflammation and fibrosis and further explore the protective effect and mechanism of RES.

METHODS AND RESULTS

RES (50 and 100 mg/kg.bw) was administered to C57BL/6J mice that were exposed to ambient PM for 5 months. The control group breathed filtered air without RES, and the PM group was exposed to PM without RES. The inflammatory cytokine levels in bronchoalveolar lavage fluid (BALF) and lung fibrosis were evaluated by enzyme-linked immune sorbent assay (ELISA) kits and Masson's trichrome staining. The real-time PCR and Western blot analysis were used to determine the signal pathway. In vivo, PM exposure markedly elevated the levels of inflammatory cytokines and TGF-β1 in BALF, induced lung fibrosis. Meanwhile, PM exposure triggered autophagy process and activated the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome in lung. Also, RES treatment abolished PM-induced lung inflammation and fibrosis, and inhibited autophagic process and NLRP3 inflammasome activation. In vitro, PM_2.5-induced cytotoxicity in BEAS-2B cells dose-dependently. Besides, RES alleviated PM_2.5-induced cytotoxicity, inhibited autophagic process and NLRP3 inflammasome activity and decreased IL-1β production in BEAS-2B cells.

CONCLUSION

Long-term PM exposure induced lung inflammation and fibrosis, and RES intervention alleviated these adverse effects via inhibiting autophagy-related NLRP3 inflammasome activation.

Particulate matter of 2.5 μm or less in diameter disturbs the balance of TH17/regulatory T cells by targeting glutamate oxaloacetate transaminase 1 and hypoxia-inducible factor 1α in an asthma model

BACKGROUND

Epidemiologic evidence suggests that exposure to particulate matter of 2.5 μm or less in diameter (PM2.5) aggravates asthma.

OBJECTIVE

We sought to investigate the underlying mechanisms between PM2.5 exposure and asthma severity.

METHODS

The relationship between PM2.5 exposure and asthma severity was investigated in an asthma model with CD4⁺ T cell-specific aryl hydrocarbon receptor (AhR)-null mice. Effects of PM2.5 and polycyclic aromatic hydrocarbons (PAHs) on differentiation of T_H17/regulatory T (Treg) cells were investigated by using flow cytometry and quantitative RT-PCR. Mechanisms were investigated by using mRNA sequencing, chromatin immunoprecipitation, bisulfite sequencing, and glycolysis rates.

RESULTS

PM2.5 impaired differentiation of Treg cells, promoted differentiation of T_H17 cells, and aggravated asthma in an AhR-dependent manner. PM2.5 and one of its prominent PAHs, indeno[1,2,3-cd]pyrene (IP), promoted differentiation of T_H17 cells by upregulating hypoxia-inducible factor 1α expression and enhancing glycolysis through AhRs. Exposure to PM2.5 and IP enhanced glutamate oxaloacetate transaminase 1 (Got1) expression through AhRs and accumulation of 2-hydroxyglutarate, which inhibited ten-eleven translocation methylcytosine dioxygenase 2 activity, resulting in hypermethylation in the forkhead box P3 locus and impaired differentiation of Treg cells. A GOT1 inhibitor, (aminooxy)acetic acid, ameliorated asthma by shifting differentiation of T_H17 cells to Treg cells. Similar regulatory effects of exposure to PM2.5 or IP on T_H17/Treg cell imbalance were noted in human T cells, and in a case-control design PAH exposure appeared to be a potential risk factor for asthma.

CONCLUSIONS

The AhR-hypoxia-inducible factor 1α and AhR-GOT1 molecular pathways mediate pulmonary responses on exposure to PM2.5 through their ability to disturb the balance of T_H17/Treg cells.

Regulation effects of naringin on diesel particulate matter-induced abnormal airway surface liquid secretion

BACKGROUND

PM_2.5 is closely related to the incidence and mortality of respiratory diseases. Diesel particulate matter (DPM) is the main component of particulate air pollution and an important source of PM_2.5.

HYPOTHESIS/PURPOSE

This study mainly explored the effect of DPM on airway surface liquid (ASL) secretion and the regulation of naringin in this process, to evaluate therapeutic potentials of naringin for the treatment of abnormal secretion of the respiratory tract caused by PM_2.5.

METHODS

The concentration of lysozyme was measured by Lysozyme Assay Kit. Total protein content was determined by the BCA Protein Assay Kit. The concentration of cAMP and MUC5AC, expressions of CFTR, AQP1, and AQP5 proteins were measured by ELISA. Expressions of CFTR, AQP1 and AQP5 mRNA were determined by qPCR. Amount of CFTR on the cell membrane was determined by immunofluorescence.

RESULTS

The in vitro and in vivo studies had indicated that DPM could inhibit ASL secretion and increased the viscosity of the liquid. Naringin had the functions to attenuate DPM-induced injury, reduce liquid viscosity by reducing MUC5AC and total protein secretion, increase DPM-induced CFTR, AQP1, and AQP5 mRNA and protein expression, positively regulate apical CFTR insertion and promote CFTR activation by increasing intracellular cAMP.

CONCLUSION

These results demonstrated that naringin had regulating effects on the DPM-induced abnormal secretion of the respiratory tract.

Inhibitory Effects of Black Ginseng on Particulate Matter-Induced Pulmonary Injury

Inhalation of fine particulate matter (PM2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. Black ginseng (BG), steamed and dried ginseng nine times, exhibits various pharmacological activities such as antibacterial, antihyperglycemic, anti-atopic, antibacterial, and anti-inflammatory activities. In this study, we investigated the beneficial effects of black ginseng extract (BGE) against PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM2.5-treated ECs and mice. BGE significantly scavenged PM2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase (MAPK). Concurrently, BGE activated Akt, which helped maintain endothelial integrity. Furthermore, BGE reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid in PM-induced lung tissues. These results indicated that BGE may exhibit protective effects against PM-induced inflammatory lung injury and vascular hyperpermeability.

Inhibitory effects of collismycin C and pyrisulfoxin A on particulate matter-induced pulmonary injury

BACKGROUND

Inhalation of fine particulate matter (PM_2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. Marine microbial natural products isolated from microbial culture broths were screened for pulmonary protective effects against PM_2.5. Two 2,2'-bipyridine compounds isolated from a red alga-associated Streptomyces sp. MC025-collismycin C (2) and pyrisulfoxin A (5)-were found to inhibit PM_2.5-mediated vascular barrier disruption.

PURPOSE

To confirm the inhibitory effects of collismycin C and pyrisulfoxin A on PM_2.5-induced pulmonary injury STUDY DESIGN: In this study, we investigated the beneficial effects of collismycin C and pyrisulfoxin A on PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation.

METHODS

Permeability, leukocyte migration, proinflammatory protein activation, reactive oxygen species (ROS) generation, and histology were evaluated in PM_2.5-treated ECs and mice.

RESULTS

Collismycin C and pyrisulfoxin A significantly scavenged PM_2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase as well as activated Akt, which helped in maintaining endothelial integrity, in purified pulmonary endothelial cells. Furthermore, collismycin C and pyrisulfoxin A reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid of PM-treated mice.

CONCLUSION

These data suggested that collismycin C and pyrisulfoxin A might exert protective effects on PM-induced inflammatory lung injury and vascular hyperpermeability.

Inhibitory effects of compounds isolated from Dioscorea batatas Decne peel on particulate matter-induced pulmonary injury in mice

Particulate matter 2.5 (PM_2.5), with an aerodynamic diameter of ≤2.5 μm, is the primary air pollutant that plays a key role associated with lung injury produced by loss of vascular barrier integrity. Dioscorea batatas Decne (Chinese yam), a perennial plant belonging to Dioscoreaceae family, is widely cultivated in tropical and subtropical regions across Asia. Both aerial parts and root of D. batatas are consumed for nutritional and medicinal purposes. The aim of this study was to (1) identify the bioactive compounds present in D. batatas peel which may be responsible for inhibition of PM_2.5-induced pulmonary inflammation in mice and (2) examine in vitro mechanisms underlying the observed effects of these compounds on mouse lung microvascular endothelial cells. The measured parameters include permeability, leukocyte migration, proinflammatory protein activation, reactive oxygen species (ROS) generation, and histology. Two phenanthrene compounds, 2,7-dihydroxy-4,6-dimethoxyphenanthrene (1) and 6,7-dihydroxy-2,4-dimethoxyphenanthrene (2) were isolated from D. batatas peels. Both these phenanthrene compounds exhibited significant scavenging activity against PM_2.5-induced ROS and inhibited ROS-induced activation of p38 mitogen-activated protein kinase. In addition, enhancement of Akt pathway, involved in the maintenance of endothelial integrity, was noted. These phenanthrene compounds also reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in the bronchoalveolar lavage fluid obtained from PM_2.5-induced lung tissues. Evidence thus indicates that phenanthrene compounds derived from D. batatas may exhibit protective effects against PM_2.5-induced inflammatory lung injury and vascular hyperpermeability in mice.

The association of PM2.5 with airway innate antimicrobial activities of salivary agglutinin and surfactant protein D

Fine particulate matter ≤2.5 μm (PM_2.5) is a prominent global public health risk factor that can cause respiratory infection by downregulating the amounts of antimicrobial proteins and peptides (AMPs). Both salivary agglutinin (SAG) and surfactant protein D (SPD) are important AMPs in respiratory mucosal fluid, providing protection against airway pathogen invasion and infection by inducing microbial aggregation and enhancing pathogen clearance. However, the relationship between PM_2.5 and these AMPs is unclear. To better understand the relationship between PM_2.5 and airway innate immune defenses, we review the respiratory antimicrobial activities of SAG and SPD, as well as the adverse effects of PM_2.5 on airway innate antimicrobial defense. We speculate there exists a dual effect between PM_2.5 and respiratory antimicrobial activity, which means that PM_2.5 suppresses respiratory antimicrobial activity through downregulating airway AMPs, while airway AMPs accelerate PM_2.5 clearance by inducing PM_2.5 microbial aggregation. We propose further research on the relationship between PM_2.5 and these AMPs.

Inhibitory effects of Kyung-Ok-Ko, traditional herbal prescription, on particulate matter-induced vascular barrier disruptive responses

Inhalation of fine particulate matter (PM_2.5) is associated with elevated pulmonary injury caused by the loss of vascular barrier integrity. A traditional herbal prescription, Kyung-Ok-Ko (KOK), has long been used in Oriental medicine as a tonic for age-related diseases. In this study, we investigated the beneficial effects of KOK on PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM_2.5-treated EC and mice. KOK significantly scavenged PM_2.5-induced ROS and inhibited the ROS-induced activation of p38 mitogen-activated protein kinase (MAPK). Concurrently, KOK activated Akt, which helped maintain endothelial integrity. Furthermore, KOK reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in bronchoalveolar lavage fluids in PM-induced lung tissues. These data suggested that KOK might exhibit protective effects in PM-induced inflammatory lung injury and vascular hyperpermeability.

Exposure to Atmospheric Ultrafine Particles Induces Severe Lung Inflammatory Response and Tissue Remodeling in Mice

Exposure to particulate matter (PM) is leading to various respiratory health outcomes. Compared to coarse and fine particles, less is known about the effects of chronic exposure to ultrafine particles, despite their higher number and reactivity. In the present study, we performed a time-course experiment in mice to better analyze the lung impact of atmospheric ultrafine particles, with regard to the effects induced by fine particles collected on the same site. Trace element and PAH analysis demonstrated the almost similar chemical composition of both particle fractions. Mice were exposed intranasally to FF or UFP according to acute (10, 50 or 100 µg of PM) and repeated (10 µg of PM 3 times a week during 1 or 3 months) exposure protocols. More particle-laden macrophages and even greater chronic inflammation were observed in the UFP-exposed mice lungs. Histological analyses revealed that about 50% of lung tissues were damaged in mice exposed to UFP for three months versus only 35% in FF-exposed mice. These injuries were characterized by alveolar wall thickening, macrophage infiltrations, and cystic lesions. Taken together, these results strongly motivate the update of current regulations regarding ambient PM concentrations to include UFP and limit their emission.

Histone modification in the lung injury and recovery of mice in response to PM2.5 exposure

Epidemiological and experimental studies have progressively provided a better knowledge of the underlying mechanisms by which fine particulate matter (PM_2.5) exerts its harmful health effects. However, limited studies focused on the effect and following recovery after the particulate exposure ended. In this study, we determined PM_2.5 exposure-caused effects on the lung and their recovery in mice after terminating aspiration, and clarified the possible molecular modification. The results revealed that PM_2.5 exposure for 4 weeks significantly decreased the lung function, and the changes returned to normal levels after 1-week recovery. However, we observed persistent particle alveolar load following 2-week recovery. Interestingly, the alterations of H3K27ac expression and related enzyme activities mimicked the changes of respiratory function during the process, and chromatin immunoprecipitation-seqences (ChIP-seq) suggested that these PM_2.5-associated differential H3K27ac markers participated in immune responses and chemokine signaling pathway with stat2 and bcar1 being two important genes. Consistently, the expression of pro-inflammatory cytokines and chemokines elevated after PM_2.5 exposure for 4-week, and reversed to normal levels following 2-week recovery. The study highlighted that PM_2.5 aspiration caused histone modification associated lung dysfunction and inflammation, and the action restored after exposure ending and 2-week recovery. Also, persistent particle alveolar load might be a long-term potential risk for lung diseases.

Inhibitory effects of protopanaxatriol type ginsenoside fraction (Rgx365) on particulate matter-induced pulmonary injury

Inhalation of fine particulate matter (PM_2.5) is associated with elevated pulmonary injury attributed to the loss of vascular barrier integrity. Black ginseng (BG), steamed 9 times and dried ginseng, and its major protopanaxatriol type ginsenosides (ginsenoside Rg4, Rg6, Rh4, Rh1, and Rg2) exhibited various biological activities including anti-septic, anti-diabetic, wound healing, immune-stimulatory, and anti-antioxidant activity. The aim of this study was to investigate the beneficial effects of Rgx365 (a protopanaxatriol type rare ginsenosides fraction) on PM-induced lung endothelial cell (EC) barrier disruption and pulmonary inflammation. Permeability, leukocyte migration, activation of proinflammatory proteins, generation of reactive oxygen species (ROS), and histology were examined in PM_2.5-treated EC and mice. Rgx365 significantly scavenged PM_2.5-induced ROS, inhibited ROS-induced activation of p38 mitogen-activated protein kinase (MAPK), activated Akt in purified pulmonary EC, which helped maintain endothelial integrity. Further, Rgx365 reduced vascular protein leakage, leukocyte infiltration, and proinflammatory cytokine release in bronchoalveolar lavage fluids in PM-induced mouse lung tissues. Data suggested that Rgx365 might exhibit protective effects in PM-induced inflammatory lung injury and vascular hyperpermeability.

Ambient fine particulate matter inhibits innate airway antimicrobial activity in preschool children in e-waste areas

Ambient fine particulate matter (PM_2.5) is a risk factor for respiratory diseases. Previous studies suggest that PM_2.5 exposure may down-regulate airway antimicrobial proteins and peptides (AMPs), thereby accelerating airway pathogen infection. However, epidemiological research is scarce. Hence, we estimated the associations between individual PM_2.5 chronic daily intake (CDI) and the levels of the airway AMP salivary agglutinin (SAG), as well as peripheral leukocyte counts and pro-inflammatory cytokines, of preschool children in Guiyu (an e-waste area) and Haojiang (a reference area located 31.6 km to the east of Guiyu). We recruited 581 preschool children from Guiyu and Haojiang, of which 222 were included in this study for a matching design (Guiyu: n = 110 vs. Haojiang: n = 112). Air PM_2.5 pollution data was collected to calculate individual PM_2.5 CDI. The mean concentration of PM_2.5 in Guiyu was higher than in Haojiang, resulting in a higher individual PM_2.5 CDI. Concomitantly, saliva SAG levels were lower in Guiyu children (5.05 ng/mL) than in Haojiang children (8.68 ng/mL), and were negatively correlated with CDI. Additionally, peripheral counts of white blood cells, and the concentrations of interleukin-8 and tumor necrosis factor-alpha, in Guiyu children were greater than in Haojiang children, and were positively associated with CDI. Similar results were found for neutrophils and monocytes. To our knowledge, this is the first study on the relationship between PM_2.5 exposure and innate airway antimicrobial activity in children, in an e-waste area, showing that PM_2.5 pollution may weaken airway antimicrobial activity by down-regulation of saliva SAG levels, which might accelerate airway pathogen infection in children.

Essential oil from Korean Chamaecyparis obtusa leaf ameliorates respiratory activity in Sprague‑Dawley rats and exhibits protection from NF-κB-induced inflammation in WI38 fibroblast cells

To date, Korean hinoki cypress (Chamaecyparis obtusa), has been widely used for household and commercial purposes. Although the medicinal efficacy of hinoki cypress essential oil has been observed, that of the essential oil‑derived terpenes, which exhibit a mechanism that acts against lung inflammation, remains to be fully elucidated. The present study investigated the anti‑inflammatory effect of hinoki cypress leaf extracted essential oil on lipopolysaccharide (LPS)‑stimulated WI38 fibroblast cells by inhibiting the nuclear factor κ‑light‑chain‑enhancer of activated B cells (NF‑κB) pathway, which exhibited lung tissue protection through the olfactory administration of essential oil in Sprague‑Dawley rats. GC/MS analysis derived 24 terpenes from the essential oil. The morphological observations revealed that, upon LPS stimulation of WI38 fibroblast cells, inflammation was induced, whereas the condition of the cells reverted to normal in the essential oil extract pre‑treated group. The results of western blot analysis revealed the inhibition of inducible nitric oxide synthase, activation of cyclooxygnase‑2, and the degradation of cytosolic p65 and inhibitor of NF‑κB‑α in the LPS‑stimulated group. Additionally, confocal imaging of nuclei revealed the translocation of phosphorylated p65, which was recovered in the cytosol in the phytoncide essential oil pre‑treated group. Histopathological observation revealed that the alveolar capacity was enhanced in the essential oil olfactory administered rat group, compared with that in the normal rat group. These findings suggest that terpenes in essential oil from the Chamaecyparis obtusa leaf have therapeutic potential against respiratory inflammation‑related disease.

Short-term Haze Exposure Predisposes Healthy Volunteers to Nasal Inflammation

PURPOSE

This study aimed to investigate the impact of short-term haze exposure on nasal inflammation in healthy volunteers.

METHODS

Thirty-three healthy university students were assessed for nasal symptoms, nasal patency, upper and lower respiratory tract nitric oxide (NO) as well as inflammatory mediators and neuropeptides in nasal secretions before and after a 5-day haze episode. Peripheral blood mononuclear cells (PBMCs) were stimulated with particulate matter with an aerodynamic diameter of less than 2.5 μm (PM_2.5), and cytokines in the supernatants were examined.

RESULTS

Mild nasal symptoms were reported by some participants during the haze episode. Objective measures of nasal patency demonstrated that nasal airway resistance was significantly increased from baseline levels, while nasal cavity volume and minimum cross-sectional area were significantly decreased. Similarly, the levels of nasal and exhaled NO, eotaxin, interleukin (IL)-5, chemokine (C-C motif) ligand 17, IL-8, substance P, nerve growth factor and vasoactive intestinal peptides in nasal secretions were significantly increased from baseline values following the haze episode. In contrast, the levels of interferon-γ, IL-10, transforming growth factor-β and neuropeptide Y were significantly decreased. Incubation with 0.1-10 μg/mL PM2.5 significantly increased release of IL-1β, IL-4, IL-5, IL-8 and IL-10 from PBMCs.

CONCLUSIONS

Short-term haze exposure may lead to nasal inflammation and hypersensitivity in healthy subjects predominantly by Th2 cytokine-mediated immune responses.

Roles of mitochondrial ROS and NLRP3 inflammasome in multiple ozone-induced lung inflammation and emphysema

Background

Mitochondrial damage leading to oxidant stress may play an important role in the pathogenesis of airflow obstruction and emphysema. NLPR3 inflammasome can be activated by mitochondrial ROS (mtROS) and other stimuli. We examined the importance of mtROS and NLRP3 inflammasome and their interactions in multiple ozone-induced lung inflammation and emphysema.

Methods

C57/BL6 mice were exposed to ozone (2.5 ppm, 3 h) or filtered air twice a week over 6 weeks. MitoTEMPO (20 mg/kg), an inhibitor of mtROS, and VX765 (100 mg/kg), an inhibitor of caspase-1 activity, were administered by intraperitoneal or intragastric injection respectively 1 h prior to each ozone exposure for 6 weeks.

Results

Ozone-exposed mice had increased bronchoalveolar lavage (BAL) total cells and levels of IL-1β, KC and IL-6, augmented lung tissue inflammation scores, enhanced oxidative stress with higher serum 8-OHdG concentrations, emphysema with greater mean linear intercept (Lm), airway remodeling with increased airway smooth muscle mass and airflow limitation as indicated by a reduction in the ratio of forced expiratory volume at 25 and 50 milliseconds to forced vital capacity (FEV₂₅/FVC, FEV₅₀/FVC). Both MitoTEMPO and VX765 reduced lung inflammation scores, cytokine levels, oxidative stress and increased mitochondrial fission proteins. VX765 also attenuated emphysema, airway remodeling and airflow limitation. MitoTEMPO inhibited the increased expression of mitochondrial complex II and IV and of NLPR3 while VX765 inhibited the expression and activity of NLRP3 and caspase-1 pathway in the lung.

Conclusions

Both mtROS and NLRP3 inflammasome play a role in ozone-induced lung inflammation while only NLRP3 is involved in ozone-induced emphysema.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0931-8) contains supplementary material, which is available to authorized users.

Fine particulate matter (PM2.5): The culprit for chronic lung diseases in China

Air pollution is a world public health problem. Particulate matter (PM), a mix of solid and liquid particles in the air, becomes an increasing concern in the social and economic development of China. For decades, epidemiological studies have confirmed the association between fine particle pollutants and respiratory diseases. It has been reported in different populations that increased Fine particulate matter (PM_2.5) concentrations cause elevated susceptibility to respiratory diseases, including acute respiratory distress, asthma, chronic obstructive pulmonary disease, and lung cancer. This review will discuss the pathophysiology of PM_2.5 in respiratory diseases, which are helpful for the prevention of air pollution and treatment of respiratory tract inflammatory diseases.

The Kidney Injury Induced by Short-Term PM2.5 Exposure and the Prophylactic Treatment of Essential Oils in BALB/c Mice

PM_2.5 is well known as a major environmental pollutant; it has been proved to be associated with kidney diseases. The kidney damage involves oxidative stress and/or inflammatory response. NOX4 is a major source of reactive oxygen species (ROS) generation in the kidney, and the excessive generation of ROS is recognized to be responsible for oxidative stress. To elucidate whether short-term PM_2.5 exposure could induce kidney damage, we exposed BALB/c mice to PM_2.5 intratracheally and measured the biomarkers of kidney injury (KIM-1, cystatin C), oxidative stress (MDA, SOD-1, and HO-1), and inflammatory response (NF-κB, TNF-α). Acute kidney damage and excessive oxidative stress as well as transient inflammatory response were observed after PM_2.5 installation. The overexpression of some components of the angiotensin system (RAS) after PM_2.5 exposure illustrated that RAS may be involved in PM_2.5-induced acute kidney injury. CEOs (compound essential oils) have been widely used because of their antioxidant and anti-inflammation properties. Treatment with CEOs substantially attenuated PM_2.5-induced acute kidney injury. The suppression of RAS activation was significant and earlier than the decrease of oxidative stress and inflammatory response after CEOs treatment. We hypothesized that CEOs could attenuate the acute kidney injury by suppressing the RAS activation and subsequently inhibit the oxidative stress and inflammatory response.

Effects of exposure estimation errors on estimated exposure-response relations for PM2.5

Associations between fine particulate matter (PM2.5) exposure concentrations and a wide variety of undesirable outcomes, from autism and auto theft to elderly mortality, suicide, and violent crime, have been widely reported. Influential articles have argued that reducing National Ambient Air Quality Standards for PM2.5 is desirable to reduce these outcomes. Yet, other studies have found that reducing black smoke and other particulate matter by as much as 70% and dozens of micrograms per cubic meter has not detectably affected all-cause mortality rates even after decades, despite strong, statistically significant positive exposure concentration-response (C-R) associations between them. This paper examines whether this disconnect between association and causation might be explained in part by ignored estimation errors in estimated exposure concentrations. We use EPA air quality monitor data from the Los Angeles area of California to examine the shapes of estimated C-R functions for PM2.5 when the true C-R functions are assumed to be step functions with well-defined response thresholds. The estimated C-R functions mistakenly show risk as smoothly increasing with concentrations even well below the response thresholds, thus incorrectly predicting substantial risk reductions from reductions in concentrations that do not affect health risks. We conclude that ignored estimation errors obscure the shapes of true C-R functions, including possible thresholds, possibly leading to unrealistic predictions of the changes in risk caused by changing exposures. Instead of estimating improvements in public health per unit reduction (e.g., per 10 µg/m3 decrease) in average PM2.5 concentrations, it may be essential to consider how interventions change the distributions of exposure concentrations.

The airway inflammation induced by nasal inoculation of PM2.5 and the treatment of bacterial lysates in rats

Particulate matter (PM) is one of the most important environmental issues in China. This study aimed to explore the correlation between PM2.5 and airway inflammation in healthy rats. The PM2.5 group was given an intranasal instillation of PM2.5 suspension on 15 consecutive days, and each received oral saline from day 16 to 90. The BV intervention group was treated as the PM2.5 exposure group, except that BV instead of saline was given daily. A histopathologic examination was performed to evaluate the airway inflammation. The prevalence and function of Th1/Th2/Treg/Th17 cells were detected by flow cytometry and ELISA. The expression of AhR was detected by western blot and real-time PCR. We found that epithelial damage and increased infiltration of inflammatory cell were present in the airways after PM2.5 exposure; there was an immune imbalance of Th cells in the PM2.5 group; the expression of AhR was increased in the airways after PM2.5 exposure. In the PM2.5 + BV group, we demonstrated alleviated immune imbalance and reduced inflammatory cell infiltration in the airways. Our study showed that exposure to PM2.5 induced airway inflammation. The imbalance of Th1/Th2/Treg/Th17 in PM2.5-induced airway inflammation might be associated with activation of the AhR pathway. Oral BV reduces PM2.5-induced airway inflammation and regulates systemic immune responses in rats.

Insights in particulate matter-induced allergic airway inflammation: Focus on the epithelium

Outdoor air pollution is a major environmental health problem throughout the world. In particular, exposure to particulate matter (PM) has been associated with the development and exacerbation of several respiratory diseases, including asthma. Although the adverse health effects of PM have been demonstrated for many years, the underlying mechanisms have not been fully identified. In this review, we focus on the role of the lung epithelium and specifically highlight multiple cytokines in PM-induced respiratory responses. We describe the available literature on the topic including in vitro studies, findings in humans (ie observations in human cohorts, human controlled exposure and ex vivo studies) and in vivo animal studies. In brief, it has been shown that exposure to PM modulates the airway epithelium and promotes the production of several cytokines, including IL-1, IL-6, IL-8, IL-25, IL-33, TNF-α, TSLP and GM-CSF. Further, we propose that PM-induced type 2-promoting cytokines are important mediators in the acute and aggravating effects of PM on airway inflammation. Targeting these cytokines could therefore be a new approach in the treatment of asthma.

Biological effects of airborne fine particulate matter (PM2.5) exposure on pulmonary immune system

Airborne fine particulate matter (PM_2.5) attracts more and more attention due to its environmental effects. The immune system appears to be a most sensitive target organ for the environmental pollutants. Inhaled PM_2.5 can deposit in different compartments in the respiratory tract and interact with epithelial cells and resident immune cells. Exposed to PM_2.5 can induce local or systematic inflammatory responses. This review focus on the effects of respiratory tract exposed to PM_2.5. Firstly, we introduced the major emission sources, basic characteristics of PM_2.5 and discussed its immunoadjuvant potential. Secondly, we elaborated the immune cells in the respiratory tract and the deposition of PM_2.5 regarding the structural characteristics of the respiratory tract. Furthermore, we summarized the in vivo/vitro studies that revealed the immunotoxic effects of PM_2.5 exposure to pulmonary cellular effectors and explored the contribution of PM_2.5 exposure to the Th1/Th2 balance.

Effects on IL-1β signaling activation induced by water and organic extracts of fine particulate matter (PM2.5) in vitro

Fine particulate matter (PM_2.5) air pollution poses a major risk to human health worldwide, and absorbed chemicals play a key role in determining the toxicity of PM_2.5. After inhalation and entry into the lungs, PM_2.5 components induce pro-inflammatory cytokines (e.g., interleukin (IL)-1β) in pulmonary cells. To test whether PM_2.5 components induce IL-1β through signing pathways that include the toll-like receptor 4 (TLR4)/nuclear factor-κ-gene binding (NF-κB), nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3), we exposed the mouse macrophage cell-line RAW264.7 to both water and organic extracts of PM_2.5 sampled over a 1-year period in Beijing, China. Varying degrees of oxidative stress and inflammatory responses were induced following exposure, while organic extracts of PM_2.5 collected during the heating season induced more significant responses. This response is attributed to high concentrations of polycyclic aromatic hydrocarbons (PAHs) originating from coal combustion and biomass burning for domestic heating. The inhibition of signaling molecules suggested that increased IL-1β was associated with the TLR4/NF-κB pathway and NLRP3 inflammasome activation, with a slightly difference between water and organic extracts exposure groups, which was likely the result of different chemical components. Our study elucidated a potentially important mechanism by which PM_2.5 components could trigger pulmonary inflammation, thus improving our understanding of the deleterious effects of this important and prevalent form of air pollution.

Oxygen content determines the bio-reactivity and toxicity profiles of carbon black particles

In spite of the considerable efforts invested to understand the environmental health and safety (EHS) impacts of ultrafine particles, such as the representative PM2.5, there are still significant knowledge gaps to be filled. No conclusive understandings have been obtained about the physicochemical determinants in accounting for differential adverse outcomes. Here we compared the cytotoxicity of four carbon black (CB) particles with similar physicochemical properties except for their oxygen contents (C824455 < C1864 < Printex U < SB4A). We found that these four CB particles manifested in vitro and in vivo cytotoxicity reversely related to their oxygen contents, namely a hierarchy of cytotoxicity: C824455 > C1864 > Printex U > SB4A. Among these CB particles, the most significant lung injury (e.g. collapses and inflammation) and macrophagic activation were found for C824455 and C1864, in particular for C824455. All these differences in toxicity profiles, including in vitro and in vivo cytotoxicity, pro-inflammatory effects and direct damages to the lung epithelia, should be (at least partially) ascribed to the oxygen content in these CB particles that in turn determined their transformation, i.e. the different aggregation states. Nonetheless, PM2.5 likewise caused severe in vivo and in vitro toxicities to the lung cells and macrophages. This study thus offers more insights into the structure-activity relationship (SAR) and opens a new avenue to elucidate the physicochemical determinants in evoking lung injuries by ultrafine airborne particles.

High molecular weight hyaluronan attenuates fine particulate matter-induced acute lung injury through inhibition of ROS-ASK1-p38/JNK-mediated epithelial apoptosis

Inhalation of fine particulate matter (PM_2.5) is asscoiated with lung injury. High molecular weight hyaluronan (HMW-HA) is an essential constituent of extracellular matrix (ECM), exhibiting anti-oxidative and anti-inflammatory properties when administered by injection, inhalation, nebulization or gene delivery of HA synthases. The aim of the present study is to determine whether HMW-HA alleviates PM_2.5-induced acute lung injury (ALI) and investigate the underlying mechanisms. We observed that HMW-HA suppressed pathological injury, inflammation, oxidative stress, edema and epithelial damage caused by PM_2.5 in the lungs of the rats. The protective mechanism of HMW-HA was further explored in vitro. The results elucidated that reactive oxygen species (ROS) was involved in PM_2.5-induced cell apoptosis, and HMW-HA mitigated the oxidative potential of PM_2.5, subsequently inhibiting phosphorylation of ASK1 at Thr845, downstream phosphorylation of p38 and JNK, and eventual apoptosis. Our study indicates that HMW-HA is a promising strategy in the prevention of PM_2.5-induced pulmonary damage.

Mediating Role of TRPV1 Ion Channels in the Co-exposure to PM2.5 and Formaldehyde of Balb/c Mice Asthma Model

Asthma is a complex pulmonary inflammatory disease that can be promoted by air pollutants such as PM2.5 and formaldehyde (FA). However, existent experimental evidence principally focuses on the negative influence of a single air pollutant, neglecting the possible synergistic effect in biological responses to mixture of these pollutants, a more common situation in our daily life. In this study, allergic Balb/c mice were exposed to a mixture of PM2.5 and FA, and their toxicological effects and mechanisms were explored. It is demonstrated that the combined exposure to PM2.5 and FA can greatly aggravate allergic asthma in mice. When compared with exposure to PM2.5 or FA alone, the co-exposure showed a certain synergistic effect. Increased levels of ROS, inflammatory factors and total serum immunoglobulin E were concomitant with this deterioration. Furthermore, results suggested that co-exposure exacerbated the activation of TRPV1 signal pathways, with an enhancement in substance P and calcitonin gene-related peptide production, which contributed to inflammation in asthma by neurogenic inflammation. The study also proved that capsazepine treatment could reduce the levels of not only pro-inflammatory neuropeptides, but also oxidative stress. It is concluded that co-exposure to PM2.5 and FA exacerbated allergic asthma through oxidative stress and enhanced TRPV1 activation.

Urban PM2.5 exacerbates allergic inflammation in the murine lung via a TLR2/TLR4/MyD88-signaling pathway

Nevertheless its mechanism has not been well explained yet, PM2.5 is recognized to exacerbate asthma. In the present study, the roles of toll-like receptor (TLR) 2, TLR4 and MyD88, in exacerbation of allergen-induced lung eosinophilia caused by urban PM2.5 was investigated. TLR2-, TLR4-, MyD88-deficient and WT BALB/c mice were intratracheally challenged with PM2.5 +/− ovalbumin (OVA) four times at 2-week intervals. PM2.5 increased neutrophil numbers and KC in bronchoalveolar lavage fluid and caused slight peribronchiolar inflammation in WT mice. However, these changes were attenuated, but not completely suppressed in gene-deficient mice, especially in MyD88^−/− mice. In WT mice, PM2.5 + OVA exacerbated OVA-related lung eosinophilia. This exacerbation includes increase of IL-5, IL-13, eotaxin and MCP-3; infiltration of eosinophils into the airway submucosa; proliferation of goblet cells in the airway epithelium; and the production of antigen-specific IgE and IgG1 in serum. All these effects were stronger in TLR2^−/− mice than in TLR4^−/− mice. In MyD88^−/− mice, this pro-inflammatory mediator-inducing ability was considerably weak and lung pathology was negligible. These results suggest that urban PM2.5 may exacerbate allergic inflammation in the murine lung via a TLR2/TLR4/MyD88-signaling pathway. PM2.5-bound trace microbial elements, such as lipopolysaccharide may be a strong candidate for exacerbation of murine lung eosinophilia.