N-acetylcysteine decreases lung inflammation and fibrosis by modulating ROS and Nrf2 in mice model exposed to particulate matter.

Background and Objectives: Air pollutants can induce and incite airway diseases such as asthma. N-acetylcysteine (NAC) affects signaling pathways involved in apoptosis, angiogenesis, cell growth and arrest, redox-regulated gene expression, and the inflammatory response. However, it is not known how NAC change redox-regulated gene expression in asthma mouse model exposed to particulate matter (PM). To investigate the effects of NAC on asthma mice exposed to PM through Reactive oxygen species (ROS), nuclear factor erythroid 2-related factor 2 (Nrf2), and mucin 5 (Muc5).Methods: To investigate the effects of NAC (100 mg/kg) on redox-regulated gene expression and lung fibrosis in a mouse model of asthma exposed to PM. A mice model of asthma induced by ovalbumin (OVA) or OVA plus titanium dioxide (OVA + TiO2) was established using wild-type BALB/c female mice, and the levels of Nrf2 and mucin 5AC (Muc5ac) proteins following NAC treatment were examined by Western blotting and immunostaining. In addition, the protein levels of ROS were checked.Results: Airway hyperresponsiveness and inflammation, goblet cell hyperplasia, and lung fibrosis were higher in OVA, OVA + TiO2 mice than in control mice. NAC diminished OVA + TiO2-induced airway hyperresponsiveness and inflammation, goblet cell hyperplasia, and lung fibrosis. Levels of ROS, Nrf2, and Muc5ac protein were higher in lung tissue from OVA + TiO2 mice than that from control mice and were decreased by treatment with NAC.Conclusions: NAC reduce airway inflammation and responsiveness, goblet cell hyperplasia, and lung fibrosis by modulating ROS and Nrf2.

Augmented angiogenic transcription factor, SOX18, is associated with asthma exacerbation.

BACKGROUND: Asthma characterized by airway hyperresponsiveness, inflammation, fibrosis, and angiogenesis. SRY-related HMG-box 18 (SOX18) is an important transcription factor involved in angiogenesis, tissue injury, wound-healing, and in embryonic cardiovascular and lymphatic vessels development. The role of angiogenic transcription factors, SOX18 and the related, prospero homeobox 1 (PROX1) and chicken ovalbumin upstream promoter transcription factor II (COUP-TFII), in asthma has had limited study. OBJECTIVE: In this study, we aimed to elucidate the role of SOX18 in the pathogenesis of bronchial asthma. METHODS: Plasma SOX18 protein was measured in control subjects, and subject with stable or exacerbated asthma. SOX18, PROX1, and COUP-TFII protein was measured by western blot, and immunohistochemistry in a murine model of ovalbumin-induced allergic asthma (OVA). SOX18, PROX1, and COUP-TFII protein was measured in lung human microvascular endothelial cells (HMVEC-L) and normal human bronchial epithelial (NHBE) cells treated with house dust mite (Der p1). RESULTS: Plasma SOX18 tended to be higher in subject with asthma compared to control subjects and increased more during exacerbation as compared to stable disease. In mice, OVA challenge lead to increased lung SOX18, PROX1, COUP-TFII, mucous gland hyperplasia and submucosal collagen. In NHBE cells, SOX18, PROX1 and COUP-TFII increased following Der p1 treatment. SOX18 protein increased in HMVEC-L following Der p1 treatment. CONCLUSION: These results suggest that SOX18 may be involved in asthma pathogenesis and be associated with asthma exacerbation.

Serum Calprotectin Is a Potential Marker in Patients with Asthma.

BACKGROUND: Calprotectin is the major cytosolic protein in neutrophil granulocytes. Although asthma is known to cause eosinophilic inflammation, some patients with asthma have non-eosinophilic inflammation, which is characterized by local neutrophilic inflammation. The aim of this study was to assess calprotectin expression levels in a mouse model of asthma, and to observe the relationship of serum calprotectin level and clinical variables in patients with asthma. METHODS: Mice were sensitized and challenged with 10 µg and 20 µg of Aspergillus fumigatus, respectively; mice treated with saline were used as a control. The levels of calprotectin were determined using enzyme-linked immunosorbent assay, immunoblotting, and immunohistochemical analysis. The serum levels of calprotectin were also assessed in patients with asthma. The relationship between calprotectin and clinicopathological characteristics was determined. RESULTS: Calprotectin, S100A8, and S100A9 expression was elevated in the mouse lungs, calprotectin levels were higher in the serum of patients with asthma (n = 33) compared with those of healthy individuals (n = 28). Calprotectin levels correlated with forced expiratory volume in one second/forced vital capacity (r = -0.215, P = 0.043), smoke amount (r = 0.413, P = 0.017), body mass index (r = -0.445, P = 0.000), and blood neutrophil percentage (r = 0.300, P = 0.004) in patients with asthma. CONCLUSION: Our data suggest that calprotectin could potentially be used as a biomarker for asthma.

Claudins, VEGF, Nrf2, Keap1, and Nonspecific Airway Hyper-Reactivity Are Increased in Mice Co-Exposed to Allergen and Acrolein.

Acrolein, an α/ß-unsaturated aldehyde, is volatile at room temperature. It is a respiratory irritant found in environmental tobacco smoke, which can be generated during cooking or endogenously at sites of injury. An acute high concentration of uncontrolled irritant exposure can lead to an asthma-like syndrome known as reactive airways dysfunction syndrome (RADS). However, whether acrolein can induce RADS remains poorly understood. The aim of study is to develop a RADS model of acrolein inhalation in mice and to clarify the mechanism of RADS. Mice were treated with ovalbumin (OVA) and exposed to acrolein (5 ppm/10 min). Airway hyper-responsiveness (AHR) was measured on days 24 and 56, and samples were collected on days 25 and 57. Tight junction protein, antioxidant-associated protein, and vascular endothelial growth factor (VEGF) levels were estimated by Western blotting and immunohistochemical staining. Reactive oxygen species (ROS) was calculated using enzyme linked immunosorbent assays. Acrolein or OVA groups exhibited an increase in airway inflammatory cells and AHR compared to a sham group. These effects were further increased in mice in the OVA + acrolein exposure group than in the OVA exposure group and persisted in the acrolein exposure group for 8 weeks. CLDNs, carbonyls, VEGF, Nrf2, and Keap1 were observed in the lungs. Our data demonstrate that acrolein induces RADS and that ROS, angiogenesis, and tight junction proteins are involved in RADS in a mouse model.

Proteomic identification of moesin upon exposure to acrolein.

BACKGROUND: Acrolein (allyl Aldehyde) as one of smoke irritant exacerbates chronic airway diseases and increased in sputum of patients with asthma and chronic obstructive lung disease. But underlying mechanism remains unresolved. The aim of study was to identify protein expression in human lung microvascular endothelial cells (HMVEC-L) exposed to acrolein. METHODS: A proteomic approach was used to determine the different expression of proteins at 8 h and 24 h after treatment of acrolein 30 nM and 300 nM to HMVEC-L. Treatment of HMVEC-L with acrolein 30 nM and 300 nM altered 21 protein spots on the two-dimensional gel, and these were then analyzed by MALDI-TOF MS. RESULTS: These proteins included antioxidant, signal transduction, cytoskeleton, protein transduction, catalytic reduction. The proteins were classified into four groups according to the time course of their expression patterns such as continually increasing, transient increasing, transient decreasing, and continually decreasing. For validation immunohistochemical staining and Western blotting was performed on lung tissues from acrolein exposed mice. Moesin was expressed in endothelium, epithelium, and inflammatory cells and increased in lung tissues of acrolein exposed mice compared with sham treated mice. CONCLUSIONS: These results indicate that some of proteins may be an important role for airway disease exacerbation caused by acrolein exposure.

Annexin A5 Protein as a Potential Biomarker for the Diagnosis of Asthma.

PURPOSE: Annexin A5 (ANXA5) has a potential role in cellular signal transduction, inflammation, and fibrosis. However, the exact role of ANXA5 in asthma remains to be clarified. The aims of the present study were to investigate ANXA5 protein expression in a mouse model of asthma and pollutant exposure and to elucidate the relationships between clinical variables and plasma ANXA5 levels in patients with asthma. METHODS: A murine model of asthma induced by ovalbumin (OVA) and titanium dioxide (TiO2) nanoparticles has been established using BALB/c mice, and we examined ANXA5 expression and lung fibrosis using this model. Moreover, we also compared ANXA5 plasma levels in patients with controlled vs. exacerbated asthma. RESULTS: ANXA5 protein levels were lower in lung tissue from OVA + OVA mice than in control mice. Lung ANXA5, connective tissue growth factor (CTGF), and transforming growth factor ß1 (TGF-ß1) protein levels were higher in OVA + TiO2-exposed mice than in control or OVA + OVA mice. Although Dermatophagoides pteronyssinus (Derp1) treatment increased lung ANXA5 protein levels in MRC-5 cells and A549 epithelial cells, it decreased lung ANXA5 levels in NHBE cells. Treatment with TiO2 nanoparticles increased lung ANXA5, CTGF, and TGF-ß1 protein levels in MRC-5 cells, A549 epithelial cells, and NHBE cells. Plasma ANXA5 levels were lower in asthmatic patients than in healthy controls, and they were significantly enriched in patients with exacerbated asthma compared with those with controlled asthma (P < 0.05). ANXA5 levels were correlated with pulmonary function as assessed by spirometry. CONCLUSION: Our results imply that ANXA5 plays a potential role in asthma pathogenesis and may be a promising marker for exacerbated bronchial asthma and exposure to air pollutants.

Annexin A1 in plasma from patients with bronchial asthma: its association with lung function.

BACKGROUND: Annexin-A1 (ANXA1) is a glucocorticoid-induced protein with multiple actions in the regulation of inflammatory cell activation. The anti-inflammatory protein ANXA1 and its N-formyl peptide receptor 2 (FPR2) have protective effects on organ fibrosis. However, the exact role of ANXA1 in asthma remains to be determined. The aim of this study was to identify the role of ANXA1 in bronchial asthma. METHODS: In mice sensitized and challenged with ovalbumin (OVA-OVA mice) and mice sensitized with saline and challenged with air (control mice), we investigated the potential links between ANXA1 levels and bronchial asthma using ELISA, immunoblotting, and immunohistochemical staining. Moreover, we also determined ANXA1 levels in blood from 50 asthmatic patients (stable and exacerbated states). RESULTS: ANXA1 protein levels in lung tissue and bronchoalveolar lavage fluid were significantly higher in OVA-OVA mice compared with control mice. FPR2 protein levels in lung tissue were significantly higher in OVA-OVA mice compared with control mice. Plasma ANXA1 levels were increased in asthmatic patients compared with healthy controls. Plasma ANXA1 levels were significantly lower in exacerbated patients compared with stable patients with bronchial asthma (p < 0.05). The plasma ANXA1 levels in controlled asthmatic patients were correlated with forced expiratory volume in 1 s (FEV1) (r = - 0.191, p = 0.033) and FEV1/forced vital capacity (FVC) (r = -0.202, p = 0.024). CONCLUSION: These results suggest that ANXA1 may be a potential marker and therapeutic target for asthma.

Impact of ozone on claudins and tight junctions in the lungs.

Claudins (CLDNs) are a major transmembrane protein component of tight junctions (TJs) in endothelia and epithelia. CLDNs are not only essential for sustaining the role of TJs in cell permeability but are also vital for cell signaling through protein-protein interactions. Ozone induces oxidative stress and lung inflammation in humans and experimental models, but the impact of ozone on claudins remains poorly understood. This study was to determine the expression of TJ proteins, such as claudin 3, 4, 5, and 14 following ozone exposure. Mice were exposed to 0.1, 1, or 2 ppm of ozone or ambient air for 6 h for 3 days. The impact of ozone on CLDNs, Nrf2, Keap1, and reactive oxygen species (ROS) were estimated using immunoblotting, immunohistochemical staining, confocal imaging, and ELISA analysis in mice and bronchial epithelial cells. Mice exposed to ozone experienced increased airway inflammatory cell infiltration and bronchial hyper-responsiveness compared to control mice. Additionally, CLDN3, CLDN4, ROS, Nrf2, and Keap1 protein expression increased, and lung CLDN14 protein expression decreased, in mice exposed to ozone compared with control mice. These results indicate that CLDNs are involved in airway inflammation following ozone exposure, suggesting that ozone affects TJ proteins through oxidative mechanisms.

Circulating angiopoietin-1 and -2 in patients with stable and exacerbated asthma.

BACKGROUND: Angiopoietin (Ang)-1 and -2 are involved in the pathogenesis of asthma and have been identified as markers of asthma severity. OBJECTIVE: To determine the relation between circulating angiopoietins and clinical variables of patients with asthma. METHODS: Fifty patients with bronchial asthma and 25 healthy controls were enrolled. Ang1 and Ang2 plasma levels were analyzed in patients with stable and exacerbated asthma. RESULTS: Plasma Ang1 levels were 28.4 ± 4.01 pg/mg in patients with bronchial asthma and 21.2 ± 5.21 pg/mg in healthy controls. Plasma Ang2 levels were 23.96 ± 1.38 pg/mg in patients with bronchial asthma compared with 36.8 ± 4.46 pg/mg in healthy controls (P = .010). The ratio of Ang2 to Ang1 was lower in patients with asthma than in control subjects. Plasma Ang1 concentrations were correlated with the ratio of forced expiratory volume in 1 second (FEV1) to forced vital capacity (FVC), and plasma Ang2 levels were correlated with FEV1 percentage of predicted, FEV1/FVC, and total immunoglobulin E values. The ratio of Ang2 to Ang1 was correlated with FEV1 percentage of predicted and FEV1/FVC. Although plasma Ang1 levels tended to be lower in the exacerbated state than in the stable state in patients with asthma, Ang2 levels were higher in the exacerbated state than in the stable state in patients with asthma (P = .001). Plasma Ang2 levels were correlated with initial eosinophil proportions and initial neutrophil proportions. Plasma Ang2 levels and the ratio of Ang2 to Ang1 were correlated with blood eosinophil proportions in the exacerbated state. CONCLUSION: These results indicate that circulating angiopoietins could be a useful marker of asthma exacerbation.

Serum angiopoietin is associated with lung function in patients with asthma: a retrospective cohort study.

BACKGROUND: Angiopoietin-1 (Ang-1) is an essential mediator of angiogenesis that establishes vascular integrity, and angiopoietin-2 (Ang-2) acts as its natural inhibitor. We considered that angiopoietin might be important in bronchial asthma. METHODS: In total, 35 patients with asthma and 20 healthy subjects were studied. RESULTS: The serum Ang-1 levels were significantly elevated in patients with asthma compared to control subjects (293.9 ± 13.8 pg/mL vs. 248.3 ± 16.2 pg/mL, respectively, p = 0.04). The serum Ang-2 levels were not different between the two groups. The areas under the curve (AUC) for serum angiopoietins revealed that the serum level of Ang-1 (0.68) was more sensitive and specific than the serum Ang-2 level (0.55) for differentiating between patients with asthma and control subjects. The serum Ang-1/Ang-2 ratio was correlated with the FEV1/FVC ratio (r = -0.312, p = 0.02), while serum Ang-2 was correlated with body mass index. CONCLUSIONS: Our results indicate that the serum Ang-1 levels were higher in asthma patients compared with healthy subjects. As the Ang-1/Ang-2 ratio was related to lung function, the data suggest that serum angiopoietin is associated with lung function in patients with asthma.

Analyzing the Impact of Diesel Exhaust Particles on Lung Fibrosis Using Dual PCR Array and Proteomics: YWHAZ Signaling.

Air pollutants are associated with exacerbations of asthma, chronic bronchitis, and airway inflammation. Diesel exhaust particles (DEPs) can induce and worsen lung diseases. However, there are insufficient data to guide polymerase chain reaction (PCR) array proteomics studies regarding the impacts of DEPs on respiratory diseases. This study was performed to identify genes and proteins expressed in normal human bronchial epithelial (NHBE) cells. MicroRNAs (miRNAs) and proteins expressed in NHBE cells exposed to DEPs at 1 µg/cm2 for 8 h and 24 h were identified using PCR array analysis and 2D PAGE/LC-MS/MS, respectively. YWHAZ gene expression was estimated using PCR, immunoblotting, and immunohistochemical analyses. Genes discovered through an overlap analysis were validated in DEP-exposed mice. Proteomics approaches showed that exposing NHBE cells to DEPs led to changes in 32 protein spots. A transcriptomics PCR array analysis showed that 6 of 84 miRNAs were downregulated in the DEP exposure groups compared to controls. The mRNA and protein expression levels of YWHAZ, ß-catenin, vimentin, and TGF-ß were increased in DEP-treated NHBE cells and DEP-exposed mice. Lung fibrosis was increased in mice exposed to DEPs. Our combined PCR array-omics analysis demonstrated that DEPs can induce airway inflammation and lead to lung fibrosis through changes in the expression levels of YWHAZ, ß-catenin, vimentin, and TGF-ß. These findings suggest that dual approaches can help to identify biomarkers and therapeutic targets involved in pollutant-related respiratory diseases.

Impact of the Junction Adhesion Molecule-A on Asthma.

PURPOSE: Junctional adhesion molecule (JAM)-A is an immunoglobulin-like molecule that colocalizes with tight junctions (TJs) in the endothelium and epithelium. It is also found in blood leukocytes and platelets. The biological significance of JAM-A in asthma, as well as its clinical potential as a therapeutic target, are not well understood. The aim of this study was to elucidate the role of JAM-A in a mouse model of asthma, and to determine blood levels of JAM-A in asthmatic patients. MATERIALS AND METHODS: Mice sensitized and challenged with ovalbumin (OVA) or saline were used to investigate the role of JAM-A in the pathogenesis of bronchial asthma. In addition, JAM-A levels were measured in the plasma of asthmatic patients and healthy controls. The relationships between JAM-A and clinical variables in patients with asthma were also examined. RESULTS: Plasma JAM-A levels were higher in asthma patients (n=19) than in healthy controls (n=12). In asthma patients, the JAM-A levels correlated with forced expiratory volume in 1 second (FEV1%), FEV1/forced vital capacity (FVC), and the blood lymphocyte proportion. JAM-A, phospho-JNK, and phospho-ERK protein expressions in lung tissue were significantly higher in OVA/OVA mice than in control mice. In human bronchial epithelial cells treated with house dust mite extracts for 4 h, 8 h, and 24 h, the JAM-A, phospho-JNK, and phospho-ERK expressions were increased, as shown by Western blotting, while the transepithelial electrical resistance was reduced. CONCLUSION: These results suggest that JAM-A is involved in the pathogenesis of asthma, and may be a marker for asthma.

Recent patents in allergy and immunology: A quantitative real-time polymerase chain reaction method for diagnosing asthma and asthma exacerbation.

Background: Asthma is diagnosed based on a history of the characteristic symptoms and evidence of expiratory airflow limitation. However, asthma diagnosis using the existing tests is associated with a risk of coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 spread. In this study, we developed a quantitative real-time polymerase chain reaction (qRT-PCR)-based asthma diagnosis tool. Methods: We detected nectin-4 in the plasma of patients with asthma using qRT-PCR, explored the relationship of clinical variables. Results: quantitative real-time polymerase chain reaction revealed that plasma nectin-4 mRNA levels were higher in asthmatics than controls. These results correlated with lung function. Conclusions: Those results suggest that qRT-PCR for nectin-4 may aid asthma diagnosis and monitoring.

Cofilin-1 and profilin-1 expression in lung microvascular endothelial cells exposed to titanium dioxide nanoparticles.

BACKGROUND: Air pollutants exacerbate chronic airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). However, the underlying mechanisms are yet to be determined. While a number of studies have reported adverse effects of nanoparticles on humans, little is known about their effects on the respiratory system. OBJECTIVES: To examine the protein expression in human lung microvascular endothelial cells (HMVEC-L) exposed to titanium dioxide (TiO2) nanoparticles, a common air pollutant. MATERIAL AND METHODS: A proteomics approach using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS) was used to determine the differences in protein expression at 8 h and 24 h, following the treatment of HMVEC-L with 20-µM or 40-µM TiO2 nanoparticles. RESULTS: Human lung microvascular endothelial cells treated with 20-µM TiO2 nanoparticles showed alterations of 7 protein spots, including molecules related to calcium regulation, transport, cytoskeleton, and muscle contraction. The treatment of HMVEC-L with 40-µM TiO2 nanoparticles resulted in alterations of 4 protein spots, with molecular functions related to the cytoskeleton, myosin regulation, actin modulation, as well as guanosine diphosphate (GDP) and guanosine triphosphate (GTP) regulation. To validate these results, immunohistochemical staining and western blotting analyses were performed on lung tissues collected from mice exposed to TiO2 nanoparticles. Cofilin-1 and profilin-1 were expressed in the endothelium, epithelium and inflammatory cells, and decreased in lung tissues of TiO2 nanoparticle-exposed mice compared to sham-treated controls. CONCLUSIONS: These results suggest that some of the differentially expressed proteins may play important roles in airway diseases caused by TiO2 nanoparticle exposure.

Nectin4 is a potential therapeutic target for asthma.

Background: Nectins comprise a family of cellular adhesion molecules involved in Ca2+-independent cellular adhesion. Neither the biological significance nor clinical potential of Nectin4 for asthma has been investigated. Objectives: The aims of this study were to elucidate the role of Nectin4 in airway inflammation and to determine the relationship between Nectin4 and clinical variables in patients with asthma. Methods: The relationship between Nectin4 levels in the blood of asthmatic patients and clinical variables was examined. Dermatophagoides pteronyssinus 1 (Der p1)-exposed normal human bronchial epithelial (NHBE) cells, and Nectin4-deficient (Nectin4-/-) and wild-type (WT) mice sensitized/challenged with ovalbumin (OVA), were used to investigate the involvement of Nectin4 in the pathogenesis of bronchial asthma via the Src/Rac1 pathway. Results: Plasma Nectin4 levels were significantly higher in asthmatic patients than controls and correlated with specific IgE D1, D2, lung function. The ROC curves for Nectin4 levels differed between asthma patients and controls. Nectin4/Afadin and Src/Rac1 levels were significantly increased in NHBE cells exposed to Der p1, but decreased in NHBE cells treated with Nectin4 siRNA. Airway obstruction and inflammation, as well as the levels of Th2 cytokines, Nectin4, and Src/Rac1, were increased in WT OVA/OVA mice compared with WT sham mice. Nectin4 knockdown resulted in lower levels of Afadin and Src/Rac1 in Nectin4-/-OVA/OVA than WT OVA/OVA mice. Conclusion: These results suggest that Nectin4 is involved in airway inflammation and may be a therapeutic target in patients with asthma.

Titanium dioxide particles modulate epithelial barrier protein, Claudin 7 in asthma.

Epithelial barrier dysfunction is involved in allergic inflammation and asthma, due to increased exposure of sub-epithelial tissues to inhaled allergens and air pollutants. The tight junction proteins claudins (CLDNs) are important regulators of paracellular permeability. CLDN7 is expressed in the alveolar epithelium; however, its contribution to airway barrier function remains unclear. The aim of this study was to assess the effects of TiO2 on epithelial barrier function in asthma. Mice were sensitized and challenged with OVA or exposed to TiO2 on days 21-23. The effect of TiO2 on CLDN7 was assessed by ELISA, immunoblotting, and immunohistochemical analysis. The levels of CLDN7 in the plasma of patients with asthma and healthy individuals were also examined. CLDN7 levels were lower in plasma from patients with asthma compared with healthy individuals. CLDN7 levels were associated with FEV1/FVC and the blood eosinophils (%) in patients with asthma. Although CLDN7 expression was elevated in the lungs of mice with asthma and in NHBE cells treated with HDM extracts, its expression was suppressed by exposure to TiO2. p-AKT and p-ERK was increased in asthmatic mice and decreased in mice with TiO2 treatment. p-AKT and p-ERK was decreased in NHBE cells treated with TiO2 and HDM extracts. Trans-epithelial electrical resistance (TEER) was higher in NHBE cells treated with TiO2 or HDM extracts; however, this was decreased by concurrent TiO2 and HDM extracts treatment. Our data suggest that particulate matter contributes to airway epithelial barrier dysfunction and results in airway inflammation and responsiveness.

Effects of Air Pollutants on Airway Diseases.

Air pollutants include toxic particles and gases emitted in large quantities from many different combustible materials. They also include particulate matter (PM) and ozone, and biological contaminants, such as viruses and bacteria, which can penetrate the human airway and reach the bloodstream, triggering airway inflammation, dysfunction, and fibrosis. Pollutants that accumulate in the lungs exacerbate symptoms of respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Asthma, a heterogeneous disease with complex pathological mechanisms, is characterized by particular symptoms such as shortness of breath, a tight chest, coughing, and wheezing. Patients with COPD often experience exacerbations and worsening of symptoms, which may result in hospitalization and disease progression. PM varies in terms of composition, and can include solid and liquid particles of various sizes. PM concentrations are higher in urban areas. Ozone is one of the most toxic photochemical air pollutants. In general, air pollution decreases quality of life and life expectancy. It exacerbates acute and chronic respiratory symptoms in patients with chronic airway diseases, and increases the morbidity and risk of hospitalization associated with respiratory diseases. However, the mechanisms underlying these effects remain unclear. Therefore, we reviewed the impact of air pollutants on airway diseases such as asthma and COPD, focusing on their underlying mechanisms.