Fine Particulate Matter and Sulfur Dioxide Coexposures Induce Rat Lung Pathological Injury and Inflammatory Responses Via TLR4/p38/NF-κB Pathway

Repetitive sulfur dioxide exposure in mice models post-deployment respiratory syndrome

Soldiers deployed to Iraq and Afghanistan have a higher prevalence of respiratory symptoms than nondeployed military personnel and some have been shown to have a constellation of findings on lung biopsy termed post-deployment respiratory syndrome (PDRS). Since many of the subjects in this cohort reported exposure to sulfur dioxide (SO2), we developed a model of repetitive exposure to SO2 in mice that phenocopies many aspects of PDRS, including adaptive immune activation, airway wall remodeling, and pulmonary vascular (PV) disease. Although abnormalities in small airways were not sufficient to alter lung mechanics, PV remodeling resulted in the development of pulmonary hypertension and reduced exercise tolerance in SO2-exposed mice. SO2 exposure led to increased formation of isolevuglandins (isoLGs) adducts and superoxide dismutase 2 (SOD2) acetylation in endothelial cells, which were attenuated by treatment with the isoLG scavenger 2-hydroxybenzylamine acetate (2-HOBA). In addition, 2-HOBA treatment or Siruin-3 overexpression in a transgenic mouse model prevented vascular remodeling following SO2 exposure. In summary, our results indicate that repetitive SO2 exposure recapitulates many aspects of PDRS and that oxidative stress appears to mediate PV remodeling in this model. Together, these findings provide new insights regarding the critical mechanisms underlying PDRS.NEW & NOTEWORTHY We developed a mice model of "post-deployment respiratory syndrome" (PDRS), a condition in Veterans with unexplained exertional dyspnea. Our model successfully recapitulates many of the pathological and physiological features of the syndrome, revealing involvement of the ROS-isoLGs-Sirt3-SOD2 pathway in pulmonary vasculature pathology. Our study provides additional knowledge about effects and long-term consequences of sulfur dioxide exposure on the respiratory system, serving as a valuable tool for future PDRS research.

Phytochemical reduces toxicity of PM2.5: a review of research progress

Studies have shown that exposure to fine particulate matter (PM2.5) affects various cells, systems, and organs in vivo and in vitro. PM2.5 adversely affects human health through mechanisms such as oxidative stress, inflammatory response, autophagy, ferroptosis, and endoplasmic reticulum stress. Phytochemicals are of interest for their broad range of physiological activities and few side effects, and, in recent years, they have been widely used to mitigate the adverse effects caused by PM2.5 exposure. In this review, the roles of various phytochemicals are summarized, including those of polyphenols, carotenoids, organic sulfur compounds, and saponin compounds, in mitigating PM2.5-induced adverse reactions through different molecular mechanisms, including anti-inflammatory and antioxidant mechanisms, inhibition of endoplasmic reticulum stress and ferroptosis, and regulation of autophagy. These are useful as a scientific basis for the prevention and treatment of disease caused by PM2.5.

Exercise-Mediated Protection against Air Pollution-Induced Immune Damage: Mechanisms, Challenges, and Future Directions

Air pollution, a serious risk factor for human health, can lead to immune damage and various diseases. Long-term exposure to air pollutants can trigger oxidative stress and inflammatory responses (the main sources of immune impairment) in the body. Exercise has been shown to modulate anti-inflammatory and antioxidant statuses, enhance immune cell activity, as well as protect against immune damage caused by air pollution. However, the underlying mechanisms involved in the protective effects of exercise on pollutant-induced damage and the safe threshold for exercise in polluted environments remain elusive. In contrast to the extensive research on the pathogenesis of air pollution and the preventive role of exercise in enhancing fitness, investigations into exercise resistance to injury caused by air pollution are still in their infancy. In this review, we analyze evidence from humans, animals, and cell experiments on the combined effects of exercise and air pollution on immune health outcomes, with an emphasis on oxidative stress, inflammatory responses, and immune cells. We also propose possible mechanisms and directions for future research on exercise resistance to pollutant-induced damage in the body. Furthermore, we suggest strengthening epidemiological studies at different population levels and investigations on immune cells to guide how to determine the safety thresholds for exercise in polluted environments.

Pathogenesis of PM2.5-Related Disorders in Different Age Groups: Children, Adults, and the Elderly

The effects of PM2.5 on human health fluctuate greatly among various age groups, influenced by a range of physiological and immunological reactions. This paper compares the pathogenesis of the disease caused by PM2.5 in people of different ages, focusing on how children, adults, and the elderly are each susceptible to it because of differences in their bodies. Regarding children, exposure to PM2.5 is linked to many negative consequences. These factors consist of inflammation, oxidative stress, and respiratory problems, which might worsen pre-existing conditions and potentially cause neurotoxicity and developmental issues. Epigenetic changes can affect the immune system and make people more likely to get respiratory diseases. On the other hand, exposures during pregnancy can change how the cardiovascular and central nervous systems develop. In adults, the inhalation of PM2.5 is associated with a wide range of health problems. These include respiratory difficulties, reduced pulmonary function, and an increased susceptibility to illnesses such as asthma, chronic obstructive pulmonary disease (COPD), and lung cancer. In addition, exposure to PM2.5 induces systemic inflammation, cardiovascular diseases, insulin resistance, and neurotoxic consequences. Evident disturbances in the immune system and cognitive function demonstrate the broad impact of PM2.5. The elderly population is prone to developing respiratory and cardiovascular difficulties, which worsen their pre-existing health issues and raise the risk of cognitive decline and neurological illnesses. Having additional medical conditions, such as peptic ulcer disease, significantly increases the likelihood of being admitted to hospital.

The impact of the synergistic effect of SO2 and PM2.5/PM10 on obstructive lung disease in subtropical Taiwan

Background

Chronic Obstructive lung diseases (COPD) are complex conditions influenced by various environmental, lifestyle, and genetic factors. Ambient air pollution has been identified as a potential risk factor, causing 4.2 million deaths worldwide in 2016, accounting for 25% of all COPD-related deaths and 26% of all respiratory infection-related deaths. This study aims to evaluate the associations among chronic lung diseases, air pollution, and meteorological factors.

Methods

This cross-sectional study obtained data from the Taiwan Biobank and Taiwan Air Quality Monitoring Database. We defined obstructive lung disease as patients with FEV1/FVC < 70%. Descriptive analysis between spirometry groups was performed using one-way ANOVA and the chi-square or Fisher's exact test. A generalized additive model (GAM) was used to evaluate the relationship between SO2 and PM2.5/PM10 through equations and splines fitting.

Results

A total of 2,635 participants were enrolled. Regarding environmental factors, higher temperature, higher relative humidity, and lower rainfall were risk factors for obstructive lung disease. SO2 was positively correlated with PM10 and PM2.5, with correlation coefficients of 0.53 (p < 0.0001) and 0.52 (p < 0.0001), respectively. Additionally, SO2 modified the relative risk of obstructive impairment for both PM10 [β coefficient (β) = 0.01, p = 0.0052] and PM2.5 (β = 0.01, p = 0.0155). Further analysis per standard deviation (per SD) increase revealed that SO2 also modified the relationship for both PM10 (β = 0.11, p = 0.0052) and PM2.5 (β = 0.09, p = 0.0155). Our GAM analysis showed a quadratic pattern for SO2 (per SD) and PM10 (per SD) in model 1, and a quadratic pattern for SO2 (per SD) in model 2. Moreover, our findings confirmed synergistic effects among temperature, SO2 and PM2.5/PM10, as demonstrated by the significant associations of bivariate (SO2 vs. PM10, SO2 vs. PM2.5) thin-plate smoothing splines in models 1 and 2 with obstructive impairment (p < 0.0001).

Conclusion

Our study showed high temperature, humidity, and low rainfall increased the risk of obstructive lung disease. Synergistic effects were observed among temperature, SO2, and PM2.5/PM10. The impact of air pollutants on obstructive lung disease should consider these interactions.

Korean Red Ginseng Prevents the Deterioration of Lung and Brain Function in Chronic PM2.5-Exposed Mice by Regulating Systemic Inflammation

This study was conducted to confirm the effects of Korean red ginseng on lung and brain dysfunction in a BALB/c mice model exposed to particulate matter (PM)2.5 for 12 weeks. Learning and cognitive abilities were assessed with Y-maze, passive avoidance, and Morris water maze tests. To evaluate the ameliorating effect of red ginseng extract (RGE), the antioxidant system and mitochondrial function were investigated. The administration of RGE protected lung and brain impairment by regulating the antioxidant system and mitochondrial functions damaged by PM2.5-induced toxicity. Moreover, RGE prevented pulmonary fibrosis by regulating the transforming growth factor beta 1 (TGF-β1) pathway. RGE attenuated PM2.5-induced pulmonary and cognitive dysfunction by regulating systemic inflammation and apoptosis via the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)/c-Jun N-terminal kinases (JNK) pathway. In conclusion, RGE might be a potential material that can regulate chronic PM2.5-induced lung and brain cognitive dysfunction.

Repetitive Sulfur Dioxide Exposure in Mice Models Post-Deployment Respiratory Syndrome

Soldiers deployed to Iraq and Afghanistan have a higher prevalence of respiratory symptoms than non-deployed military personnel and some have been shown to have a constellation of findings on lung biopsy termed post-deployment respiratory syndrome (PDRS). Since many of the deployers in this cohort reported exposure to sulfur dioxide (SO 2 ), we developed a model of repetitive exposure to SO 2 in mice that phenocopies many aspects of PDRS, including adaptive immune activation, airway wall remodeling, and pulmonary vascular disease (PVD). Although abnormalities in small airways were not sufficient to alter lung mechanics, PVD was associated with the development of pulmonary hypertension and reduced exercise tolerance in SO 2 exposed mice. Further, we used pharmacologic and genetic approaches to demonstrate a critical role for oxidative stress and isolevuglandins in mediating PVD in this model. In summary, our results indicate that repetitive SO 2 exposure recapitulates many aspects of PDRS and that oxidative stress may mediate PVD in this model, which may be helpful for future mechanistic studies examining the relationship between inhaled irritants, PVD, and PDRS.

The temporal characteristics of the disruption of gut microbiota, serum metabolome, and cytokines by silica exposure in wistar rats

Silicosis is one of the most frequent, rapidly developing, and lethal types of pneumoconiosis. However, our understanding of the underlying mechanisms of its pathogenesis and progress remains unclear. We investigated the fundamental processes of silicosis incidence and progression using a combination of lung function testing, histopathology, 16 S rRNA, untargeted metabolomics, and cytokine chips at different exposure times (4 or 8 weeks). The results show that silica exposure damages lung tissue reduces lung function, and increases with time. Cytokines with time-specific properties were found in lung lavage fluid: IFN-γ (4 weeks; P＜0.05), TNF-α, M-CSF, GM-CSF (8 weeks; P＜0.01). In addition, silica exposure for different periods interferes to varying degrees with the metabolism of lipids. The composition of the intestinal microbiota changed with increasing exposure time and there were time-specific: Allobaculum, Turicibacter、Jeotgalicoccu、Coprococcus 1 (4 weeks; P＜0.05), Ruminococcaceae NK4A214 group、Ruminiclostridium 5 (8 weeks; P＜0.05). We found strong associations between cytokines, gut microbiota changes, and metabolic disturbances at different exposure times. These results suggest that time-specific changes in crosstalk among cytokines, the gut microbiota, and metabolites may be a potential mechanism for silica-induced lung injury.

Association between ambient sulfur dioxide pollution and asthma mortality: Evidence from a nationwide analysis in China

There is a lack of research on the effects of acute exposure to ambient sulfur dioxide (SO2) on mortality caused by asthma, especially nationwide research in China. To explore the acute effect of exposure to ambient SO2 on asthma mortality using nationwide dataset in China from 2015 to 2020 and further evaluate the associations in subgroups with different geographical and demographic characteristics. We used data from China's Disease Surveillance Points system with 29,553 asthma deaths in China during 2015-2020. The exposure variable was the daily mean concentrations of SO2 from the ChinaHighSO2 10 km × 10 km daily grid dataset. Bilinear interpolation was used to estimate each individual's exposure to air pollutants and meteorological variables. We used a time-stratified case crossover design at the individual level to analyze the exposure response relationship between short-term exposure to SO2 and asthma mortality. Stratified analyses were carried out by sex, age group, marital status, warm season and cold season, urbanicity and region. Significant associations between short-term exposure to ambient SO2 and increased asthma mortality were found in this nationwide study. The excess risk (ER) for each 10 μg/m3 increase in SO2 concentrations at lag07 was 7.78 % (95 % CI, 4.16-11.52 %). Season appeared to significantly modify the association. The associations were stronger in cold season (ER 9.78 %, 95 % CI:5.82 -13.89 %). The association remained consistent using different lag periods, adjusting for other pollutants, and in the analysis during pre-Corona Virus Disease 2019 (COVID-19) period. Our study indicates increased risk of asthma mortality with acute exposures to SO2 in Chinese population. The current study lends support for greater awareness of the harmful effect of SO2 in China and other countries with high SO2 pollution.

Recent Insights into Particulate Matter (PM2.5)-Mediated Toxicity in Humans: An Overview

Several epidemiologic and toxicological studies have commonly viewed ambient fine particulate matter (PM_2.5), defined as particles having an aerodynamic diameter of less than 2.5 µm, as a significant potential danger to human health. PM_2.5 is mostly absorbed through the respiratory system, where it can infiltrate the lung alveoli and reach the bloodstream. In the respiratory system, reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress stimulate the generation of mediators of pulmonary inflammation and begin or promote numerous illnesses. According to the most recent data, fine particulate matter, or PM_2.5, is responsible for nearly 4 million deaths globally from cardiopulmonary illnesses such as heart disease, respiratory infections, chronic lung disease, cancers, preterm births, and other illnesses. There has been increased worry in recent years about the negative impacts of this worldwide danger. The causal associations between PM_2.5 and human health, the toxic effects and potential mechanisms of PM_2.5, and molecular pathways have been described in this review.

Effects of sulfur dioxide, ozone, and ambient air pollution on lung histopathology, oxidative-stress biomarkers, and apoptosis-related gene expressions in rats

PURPOSE OF THE STUDY

Ambient air pollution (AAP) has become an important health problem globally. Besides, several pieces of evidence indicate that air pollutants such as sulfur dioxide (SO₂) and ozone (O₃) are major contributors to a wide range of non-communicable diseases. The present study investigated the effects of AAP, sulfur dioxide, and ozone on oxidative stress, histopathology, and some apoptosis-related genes expressions of lung tissue in a rat model.

MATERIALS AND METHODS

Thirty-two Wistar rats were randomly divided into the control, AAP, sulfur dioxide (10 ppm), and ozone (0.6 ppm) groups. After five consecutive weeks' exposure to the selected pollutants (3 h/day), lung tissues were harvested and immediately fixed with formalin. The samples were routinely processed, sectioned, stained with hematoxylin and eosin (H&E), and finally assessed for presence of pathological changes. Expression changes of BAX, p-53, EGFR, caspase-3, caspase-8 and caspase-9 were assayed using the RT-qPCR method. One hundred milligrams of lung tissues were extracted and the supernatants were used for assaying malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (GP_X), and catalase activities.

RESULTS

GPx activity was increased in the ozone (P = 0.05) and AAP (P < 0.001) groups and also MDA level in sulfur dioxide group (P = 0.008). Pathological lesions were mild, moderate, and severe in the sulfur dioxide, ozone, and AAP groups, respectively, as compared to control group (P ˂ 0.05). Exposure to AAP and sulfur dioxide enhanced BAX (P = 0.002) and caspase-8 (P < 0.001) mRNA expression, respectively. Caspases-3 and -8 mRNA expressions were elevated in ozone group (P < 0.001).

CONCLUSIONS

The results indicated induction of oxidative stress. Our results suggest the apoptosis stimuli effect of AAP and also the extrinsic apoptotic pathway trigger effect of sulfur dioxide and ozone in the lung tissue in the concentrations used in the present study. The histopathological and the genes expression changes may be a result of the induced oxidative stress in the lung tissues.

Biomarkers for the adverse effects on respiratory system health associated with atmospheric particulate matter exposure

Large amounts of epidemiological evidence have confirmed the atmospheric particulate matter (PM_2.5) exposure was positively correlated with the morbidity and mortality of respiratory diseases. Nevertheless, its pathogenesis remains incompletely understood, probably resulting from the activation of oxidative stress, inflammation, altered genetic and epigenetic modifications in the lung upon PM_2.5 exposure. Currently, biomarker investigations have been widely used in epidemiological and toxicological studies, which may help in understanding the biologic mechanisms underlying PM_2.5-elicited adverse health outcomes. Here, the emerging biomarkers to indicate PM_2.5-respiratory system interactions were summarized, primarily related to oxidative stress (ROS, MDA, GSH, etc.), inflammation (Interleukins, FE_NO, CC16, etc.), DNA damage (8-OHdG, γH2AX, OGG1) and also epigenetic modulation (DNA methylation, histone modification, microRNAs). The identified biomarkers shed light on PM_2.5-elicited inflammation, fibrogenesis and carcinogenesis, thus may favor more precise interventions in public health. It is worth noting that some inconsistent findings may possibly relate to the inter-study differentials in the airborne PM_2.5 sample, exposure mode and targeted subjects, as well as methodological issues. Further research, particularly by -omics technique to identify novel, specific biomarkers, is warranted to illuminate the causal relationship between PM_2.5 pollution and deleterious lung outcomes.

Sulfur dioxide-induced exacerbation of airway inflammation via reactive oxygen species production and the toll-like receptor 4/nuclear factor-κB pathway in asthmatic mice

Sulfur dioxide (SO₂) is a common air pollutant that can exacerbate asthmatic airway inflammation. The mechanisms underlying these effects are not yet fully understood. In this study, we investigated the effects of SO₂ exposure (10 mg/m³) on asthmatic airway inflammation in ovalbumin-induced asthmatic mice. Our results showed that SO₂ exposure alone induced slight airway injury, decreased superoxide dismutase activity, and increased nuclear factor-κB (NF-κB) expression in the lungs of mice. Moreover, SO₂ exposure in asthmatic mice induced marked pathological damage, significantly increased the counts of inflammatory cells (e.g., macrophages, lymphocytes, and eosinophils) in bronchoalveolar lavage fluid, and significantly enhanced malondialdehyde and glutathione levels in the lungs. Moreover, the expression of toll-like receptor 4 (TLR4), NF-κB, pro-inflammatory cytokines (e.g., tumor necrosis factor α and interleukin-6), and type II T-helper cell (Th2) cytokines was found to be elevated in the mice exposed to SO₂ and ovalbumin compared to those exposed to ovalbumin alone. These results suggest that SO₂ amplifies Th2-mediated inflammatory responses, which involve reactive oxygen species and TLR4/NF-κB pathway activation; these can further enhance Th2 cytokine expression and eosinophilic inflammation. Thus, our findings provide important evidence to understand a potential mechanism through which SO₂ may exacerbate airway asthmatic inflammation.

The Impact of the Synergistic Effect of Temperature and Air Pollutants on Chronic Lung Diseases in Subtropical Taiwan

Previous studies have suggested an association between air pollution and lung disease. However, few studies have explored the relationship between chronic lung diseases classified by lung function and environmental parameters. This study aimed to comprehensively investigate the relationship between chronic lung diseases, air pollution, meteorological factors, and anthropometric indices. We conducted a cross-sectional study using the Taiwan Biobank and the Taiwan Air Quality Monitoring Database. A total of 2889 participants were included. We found a V/U-shaped relationship between temperature and air pollutants, with significant effects at both high and low temperatures. In addition, at lower temperatures (<24.6 °C), air pollutants including carbon monoxide (CO) (adjusted OR (aOR):1.78/Log 1 ppb, 95% CI 0.98–3.25; aOR:5.35/Log 1 ppb, 95% CI 2.88–9.94), nitrogen monoxide (NO) (aOR:1.05/ppm, 95% CI 1.01–1.09; aOR:1.11/ppm, 95% CI 1.07–1.15), nitrogen oxides (NO_x) (aOR:1.02/ppm, 95% CI 1.00–1.05; aOR:1.06/ppm, 95% CI 1.04–1.08), and sulfur dioxide (SO₂) (aOR:1.29/ppm, 95% CI 1.01–1.65; aOR:1.77/ppm, 95% CI 1.36–2.30) were associated with restrictive and mixed lung diseases, respectively. Exposure to CO, NO, NO₂, NO_x and SO₂ significantly affected obstructive and mixed lung disease in southern Taiwan. In conclusion, temperature and air pollution should be considered together when evaluating the impact on chronic lung diseases.

Real-world particulate matters induce lung toxicity in rats fed with a high-fat diet: Evidence of histone modifications

Exposure to ambient particulate matters (PMs) has been associated with a variety of lung diseases, and high-fat diet (HFD) was reported to exacerbate PM-induced lung dysfunction. However, the underlying mechanisms for the combined effects of HFD and PM on lung functions remain poorly unraveled. By performing a comparative proteomic analysis, the current study investigated the global changes of histone post-translational modifications (PTMs) in rat lung exposed to long-term, real-world PMs. In result, after PM exposure the abundance of four individual histone PTMs (1 down-regulated and 3 up-regulated) and six combinatorial PTMs (1 down-regulated and 5 up-regulated) were significantly altered in HFD-fed rats while only one individual PTM was changed in rats with normal diet (ND) feeding. Histones H3K18ac, H4K8ac and H4K12ac were reported to be associated with DNA damage response, and we found that these PTMs were enhanced by PM in HFD-fed rats. Together with the elevated DNA damage levels in rat lungs following PM and HFD co-exposure, we demonstrate that PM exposure combined with HFD could induce lung injury through altering more histone modifications accompanied by DNA damage. Overall, these findings will augment our knowledge of the epigenetic mechanisms for pulmonary toxicity caused by ambient PM and HFD exposure.

Subchronic exposure to concentrated ambient PM2.5 perturbs gut and lung microbiota as well as metabolic profiles in mice

Exposure to ambient fine particular matter (PM2.5) are linked to an increased risk of metabolic disorders, leading to enhanced rate of many diseases, such as inflammatory bowel disease (IBD), cardiovascular diseases, and pulmonary diseases; nevertheless, the underlying mechanisms remain poorly understood. In this study, BALB/c mice were exposed to filtered air (FA) or concentrated ambient PM2.5 (CPM) for 2 months using a versatile aerosol concentration enrichment system(VACES). We found subchronic CPM exposure caused significant lung and intestinal damage, as well as systemic inflammatory reactions. In addition, serum and BALFs (bronchoalveolar lavage fluids) metabolites involved in many metabolic pathways in the CPM exposed mice were markedly disrupted upon PM2.5 exposure. Five metabolites (glutamate, glutamine, formate, pyruvate and lactate) with excellent discriminatory power (AUC = 1, p < 0.001) were identified to predict PM2.5 exposure related toxicities. Furthermore, subchronic exposure to CPM not only significantly decreased the richness and composition of the gut microbiota, but also the lung microbiota. Strong associations were found between several gut and lung bacterial flora changes and systemic metabolic abnormalities. Our study showed exposure to ambient PM2.5 not only caused dysbiosis in the gut and lung, but also significant systemic and local metabolic alterations. Alterations in gut and lung microbiota were strongly correlated with metabolic abnormalities. Our study suggests potential roles of gut and lung microbiota in PM2.5 caused metabolic disorders.

Airway hyperresponsiveness development and the toxicity of PM2.5

Airway hyperresponsiveness (AHR) is characterized by excessive bronchoconstriction in response to nonspecific stimuli, thereby leading to airway stenosis and increased airway resistance. AHR is recognized as a key characteristic of asthma and is associated with significant morbidity. At present, many studies on the molecular mechanisms of AHR have mainly focused on the imbalance in Th1/Th2 cell function and the abnormal contraction of airway smooth muscle cells. However, the specific mechanisms of AHR remain unclear and need to be systematically elaborated. In addition, the effect of air pollution on the respiratory system has become a worldwide concern. To date, numerous studies have indicated that certain concentrations of fine particulate matter (PM2.5) can increase airway responsiveness and induce acute exacerbation of asthma. Of note, the concentration of PM2.5 does correlate with the degree of AHR. Numerous studies exploring the toxicity of PM2.5 have mainly focused on the inflammatory response, oxidative stress, genotoxicity, apoptosis, autophagy, and so on. However, there have been few reviews systematically elaborating the molecular mechanisms by which PM2.5 induces AHR. The present review separately sheds light on the underlying molecular mechanisms of AHR and PM2.5-induced AHR.

Mechanism underlying the effect of SO2-induced oxidation on human skin keratinocytes

This study aimed to study the effect and mechanism of action of SO2-induced oxidation on human skin keratinocytes.Different concentrations of SO2 derivatives (0, 25, 50, 100, 200, 400, and 800 μM) were used for treating HaCaT keratinocytes for 24 hours. MTT was used to evaluate the effect of each concentration on cell proliferation. HaCaT cells were randomly divided into control and SO2 groups. The control group received no treatment, whereas the SO2 group was treated with SO2 derivatives of selected concentrations for 24 hours. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD), tumor necrosis factor TNF-α (TNF-α), and interleukin-1 (IL-1-β) in cell supernatants were detected using enzyme-linked immunosorbent assay. Real-time polymerase chain reaction was used to detect the expression of nuclear transcription factor (Nrf2) and heme oxygenase (HO)-1 mRNA. The Western blot analysis was used to test the expression levels of Nrf2, HO-1, activated caspase-3, Bcl-2, Bax, IκB, NF-κB p65 (p65), ERK1/2, p38, phospho-NF-κB p65 (p-p65), p-ERK1/2, and p-p38.SO2 derivatives (100, 200, 400, and 800 μM) could inhibit cell proliferation. SO2 derivatives increased the level of ROS, MDA, TNF-α, IL-1β, Nrf2, HO-1, and p-p65/p65 and decreased the levels of SOD, IκB, p-ERK1/2/ERK1/2, and p-p38/p38 compared with the control group, but they had no effect on the levels of caspase-3, Bcl-2, and Bax.SO2 could inhibit the proliferation of human skin keratinocytes and induce oxidative stress and inflammation via the activation of the NF-κB pathway to inhibit the ERK1/2 and p38 pathways.

Ophiopogonin D attenuates PM2.5-induced inflammation via suppressing the AMPK/NF-κB pathway in mouse pulmonary epithelial cells

Exposure to fine particulate matter, such as particulate matter of ≤2.5 µm in diameter (PM2.5), causes pulmonary inflammation and injury to other organs. It has been reported that Ophiopogonin D (OP-D) has anti-inflammatory activity. The aim of the present study was to investigate this anti-inflammatory activity of OP-D on PM2.5-induced acute airway inflammation and its underlying mechanisms. The viability of PM2.5-treated mouse lung epithelial (MLE-12) cells with or without OP-D treatment was determined using a Cell Counting Kit-8 assay. The corresponding levels of IL-1β, IL-6, IL-8 and TNF-α were examined via ELISA. Subcellular localization of NF-κBp65 was detected using immunofluorescence staining. The expression levels of AMP-activated protein kinase (AMPK), phosphorylated (p)-AMPK, NF-κBp65 and p-NF-κBp65 were analyzed using western blotting. The selective AMPK inhibitor Compound C (CC) was utilized to investigate the involvement of AMPK in the protection against PM2.5-induced cell inflammation by OP-D treatment. The results demonstrated that OP-D significantly ameliorated the PM2.5-stimulated release of proinflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-8) and inhibited the translocation of NF-κBp65 from the cytoplasm to the nucleus in MLE-12 cells. Moreover, OP-D significantly prevented the PM2.5-triggered phosphorylation of NF-κBp65 and upregulated AMPK activity. The anti-inflammatory activity of OP-D could also be attenuated by the AMPK-specific inhibitor CC. The present results suggested that the anti-inflammatory activity of OP-D was mediated via AMPK activation and NF-κB signaling pathway downregulation, which ameliorated the expression of proinflammatory cytokines. Therefore, OP-D could be a candidate drug to treat PM2.5-induced airway inflammation.

PM2.5 impairs macrophage functions to exacerbate pneumococcus-induced pulmonary pathogenesis

Background

Pneumococcus is one of the most common human airway pathogens that causes life-threatening infections. Ambient fine particulate matter (PM) with aerodynamic diameter ≤ 2.5 μm (PM_2.5) is known to significantly contribute to respiratory diseases. PM_2.5-induced airway inflammation may decrease innate immune defenses against bacterial infection. However, there is currently limited information available regarding the effect of PM_2.5 exposure on molecular interactions between pneumococcus and macrophages.

Results

PM_2.5 exposure hampered macrophage functions, including phagocytosis and proinflammatory cytokine production, in response to pneumococcal infection. In a PM_2.5-exposed pneumococcus-infected mouse model, PM_2.5 subverted the pulmonary immune response and caused leukocyte infiltration. Further, PM_2.5 exposure suppressed the levels of CXCL10 and its receptor, CXCR3, by inhibiting the PI3K/Akt and MAPK pathways.

Conclusions

The effect of PM_2.5 exposure on macrophage activity enhances pneumococcal infectivity and aggravates pulmonary pathogenesis.

Effective fraction of Bletilla striata reduces the inflammatory cytokine production induced by water and organic extracts of airborne fine particulate matter (PM2.5) in vitro

BACKGROUND

Bletilla striata is a traditional Chinese medicine used to treat hemorrhage, scald, gastric ulcer, pulmonary diseases and inflammations. In this study, we investigated bioactivity of the effective fraction of B. striata (EFB) in reducing the inflammatory cytokine production induced by water or organic extracts of PM_2.5.

METHODS

PM_2.5 extracts were collected and analyzed by chromatographic system and inductively coupled plasma mass spectrometer. Cell viability was measured using MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay, and cell supernatant was analyzed by flow cytometry, ELISA, and qRT-PCR in cultured mouse macrophage cell line RAW264.7 treated with EFB and PM_2.5 extracts. Expressions of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathway were measured by Western blot.

RESULTS

PM_2.5 composition is complex and the toxicity of PM_2.5 extracts were not noticeable. The treatment of EFB at a wide dose-range of 0-40 μg/mL did not cause significant change of RAW264.7 cell proliferation. EFB pretreatment decreased the inflammatory cytokines in the macrophage. Further analysis showed that EFB significantly attenuated PM_2.5-induced proinflammatory protein expression and downregulated the levels of phosphorylated NF-κBp65, inhibitor of kappa B (IκB)-α, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and p38.

CONCLUSIONS

Our study demonstrated the potential effectiveness of B. striata extracts for treating PM_2.5-triggered pulmonary inflammation.

1,25-Dihydroxy Vitamin D3 Attenuates the Oxidative Stress-Mediated Inflammation Induced by PM2.5via the p38/NF-κB/NLRP3 Pathway

Vitamin D₃ is reported to be involved in the regulation of inflammatory processes. In this study, biomarkers related to oxidative stress and inflammation were investigated to clarify the protective effects and possible mechanism of 1,25-dihydroxy vitamin D₃ (1,25-(OH)₂D₃) on PM_2.5-induced inflammatory response. In the in vitro study using human bronchial epithelial (HBE) cells, aqueous extracts of PM_2.5 could induce oxidative damage which is characterized by significant increases in production of reactive oxygen species, malonaldehyde concentration, and protein expression of HSPA1A and HO-1. Meanwhile, PM_2.5 caused secretion of inflammatory factors (IL-6, IL-8) in the culture medium as well as phosphorylation of p38, nuclear factor-kappa B (NF-κB) inhibitor alpha (IκBα), and NF-κB p65 proteins. Increases in NLRP3 expression was also observed in HBE cells after PM_2.5 exposure. However, all these biomarkers were remarkably attenuated by a 24-h pretreatment of 1 nM 1,25-(OH)₂D₃. Furthermore, 1,25-(OH)₂D₃ also reduced transcriptional activation of NF-κB induced by PM_2.5 as indicated by a significant decrease in luciferase activity in HBE cells stably transfected with the NF-κB response element (RE)-driven luciferase reporter. Taken together, our findings provided novel experimental evidences supporting that vitamin D₃ could reduce the predominantly oxidative stress-mediated inflammation induced by PM_2.5via the p38/NF-κB/NLRP3 signaling pathway.

Repeat dose exposure of PM2.5 triggers the disseminated intravascular coagulation (DIC) in SD rats

Epidemiological evidence suggests that fine particulate matter (PM_2.5) in air pollution promotes the formation of deep venous thrombosis. However, no evidence is available on the effects of PM_2.5 lead to disseminated intravascular coagulation (DIC). For the first time, this study explored the effects of PM_2.5 on DIC via coagulation disorders in vivo. SD rats received intratracheal instillation of PM_2.5 once every three days for one month. Doppler ultrasound showed that the pulmonary valve (PV) and aortic valve (AV) peak flow were decreased after exposure to PM_2.5. Fibrin deposition and bleeding were observed in lung tissue and vascular endothelial injury was found after exposure to PM_2.5. Expression of thrombomodulin (TM) in vessel was downregulated after PM_2.5-treated, whereas the levels of proinflammatory factors and adhesion molecules (IL-6, IL-1β, CRP, ICAM-1 and VCAM-1) were markedly elevated after exposure to PM_2.5. Tissue factor (TF) and the coagulation factor of FXa were increased, while vWF was significantly lowered induced by PM_2.5. Thrombin-antithrombin complex (TAT) and fibrinolytic factor (t-PA) were elevated, while there was no significantly change in the expression of anticoagulant factors (TFPI and AT-III). To clarify the relationship between PM_2.5 and DIC, we examined the general diagnostic indices of DIC: PM_2.5 prolonged PT and increased the expression of D-dimer but decreased platelet count and fibrinogen. In addition, the gene levels of JAK1 and STAT3 showed an upward trend, whereas there was little effect on JAK2 expression. And inflammatory factors (IL-6, IL-1β and TNF) in blood vessels of were up-reglated in PM_2.5-treated rats. In summary, our results found that PM_2.5 could induce inflammatory response, vascular endothelial injury and prothrombotic state, eventually resulted in DIC. It will provide new evidence for a link between PM_2.5 and cardiovascular disease.

Effects of Different Components of PM2.5 on the Expression Levels of NF-κB Family Gene mRNA and Inflammatory Molecules in Human Macrophage

Background: Studies have found that exposure to fine particulate matter with sizes below 2.5 µm (PM2.5) might cause inflammation response via the NF-κB pathway. To date, only a few studies have focused on the toxicity of different components of PM2.5. We aimed to explore the effects of PM2.5 with different components on the expression levels of NF-κB family gene mRNA and inflammatory molecules in human macrophages. Methods: Human monocytic cell line THP-1-derived macrophages were exposed to water-soluble (W-PM2.5), fat-soluble (F-PM2.5), and insoluble (I-PM2.5) PM2.5. The cell survival rate was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The levels of inflammatory molecules were determined by enzyme-linked immunosorbent assay (ELISA), and the relative mRNA levels of the NF-κB family gene were determined by real time PCR. Results: PM2.5 could decrease the cell viability. After exposure to W-PM2.5, the levels of interleukins (IL)-1β and IL-12 p70 significantly increased. After exposure to F-PM2.5, the levels of IL-12 p70 significantly increased. The levels of IL-12 p70 and TNF-α after exposure to I-PM2.5 were significantly higher than that in W- and F-PM2.5 treatment groups. The levels of IL-8, C reactive protein (CRP), and cyclooxygenase (COX)-2 increased only after exposure to I-PM2.5. F-PM2.5 increased the mRNA levels of NF-κB genes, especially NF-κB1 and RelA. Conclusions: PM2.5 can decrease the cell survival rate and up-regulate the expression of NF-κB family gene mRNA and inflammatory molecules. The main toxic components of PM2.5 related to inflammatory response in macrophages were the I-PM2.5.

Mass spectrometry-based metabolomics reveals the mechanism of ambient fine particulate matter and its components on energy metabolic reprogramming in BEAS-2B cells

Exposure to airborne fine particulate matter (PM_2.5) is associated with various adverse effects. However, the molecular mechanism involved in PM_2.5-elicited energy metabolic reprogramming and the toxic chemical determinants within PM_2.5 are not well elucidated. In this study, nontargeted and targeted metabolomics research were conducted to investigate the overall metabolic changes and relevant toxicological pathways caused by Taiyuan winter total PM_2.5 and its water soluble and organic soluble fractions in human lung bronchial epithelial cells (BEAS-2B). The results showed that significant metabolome alterations in BEAS-2B cells were observed after the exposure of total PM_2.5 and its organic soluble fraction. Purine metabolism, arginine and proline metabolism, glutathione (GSH) metabolism, tricarboxylic acid (TCA) cycle and glycolysis were mainly affected. Along with a significant increase of reactive oxygen species (ROS), malondialdehyde (MDA), nitric oxide (NO) and pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β), obvious metabolic phenotype remodeling from oxidative phosphorylation to glycolysis was found in BEAS-2B cells treated with total PM_2.5 and its organic soluble fraction. Compared with water soluble fraction, organic soluble fraction was found to play the dominant role in PM_2.5 toxicity. Our study provided novel insights into the mechanism of PM_2.5-elicited toxicity.

From the Cover: Lung-Specific Overexpression of Constitutively Active IKK2 Induces Pulmonary and Systemic Inflammations but Not Hypothalamic Inflammation and Glucose Intolerance

The lung is constantly exposed to ambient pollutants such as ambient fine particulate matter (PM2.5), making it one of the most frequent locations of inflammation in the body. Given the establishment of crucial role of inflammation in the pathogenesis of cardiometabolic diseases, pulmonary inflammation is thus widely believed to be an important risk factor for cardiometabolic diseases. However, the causality between them has not yet been well established. To determine if pulmonary inflammation is sufficient to cause adverse cardiometabolic effects, SFTPC-rtTA+/-tetO-cre+/-pROSA-inhibitor κB kinase 2(IKK2)ca+/- (LungIKK2ca) and littermate SFTPC-rtTA+/-tetO-cre-/-pROSA-IKK2ca+/- wildtype (WT) mice were fed with doxycycline diet to induce constitutively active Ikk2 (Ikk2ca) overexpression in the lung and their pulmonary, systemic, adipose, and hypothalamic inflammations, vascular function, and glucose homeostasis were assessed. Feeding with doxycycline diet resulted in IKK2ca overexpression in the lungs of LungIKK2ca but not WT mice. This induction of IKK2ca was accompanied by marked pulmonary inflammation as evidenced by significant increases in bronchoalveolar lavage fluid leukocytes, pulmonary macrophage infiltration, and pulmonary mRNA expression of tumor necrosis factor α (Tnfα) and interleukin-6 (Il-6). This pulmonary inflammation due to lung-specific overexpression of IKK2ca was sufficient to increase circulating TNFα and IL-6 levels, adipose expression of Tnfα and Il-6 mRNA, aortic endothelial dysfunction, and systemic insulin resistance. Unexpectedly, no significant alteration in hypothalamic expression of Tnfα and Il-6 mRNA and glucose intolerance were observed in these mice. Pulmonary inflammation is sufficient to induce systemic inflammation, endothelial dysfunction, and insulin resistance, but not hypothalamic inflammation and glucose intolerance.

Effect of Air Pollution on Exacerbations of Bronchiectasis in Badalona, Spain, 2008-2016

INTRODUCTION

Air pollution has been widely associated with respiratory diseases. Nevertheless, the association between air pollution and exacerbations of bronchiectasis has been less studied.

OBJECTIVE

To analyze the effect of air pollution on exacerbations of bronchiectasis.

METHODS

This was a retrospective observational study conducted in Badalona. The number of daily hospital admissions and emergency room visits related to exacerbation of bronchiectasis (ICD-9 code 494.1) between 2008 and 2016 was obtained. We used simple Poisson regressions to test the effects of daily mean temperature, SO2, NO2, CO, and PM10 levels on bronchiectasis-related emergencies and hospitalizations on the same day and 1-4 days after. All p values were corrected for multiple comparisons.

RESULTS

SO2 was significantly associated with an increase in the number of hospitalizations (lags 0, 1, 2, and 3). None of these associations remained significant after correcting for multiple comparisons. The number of emergency room visits was associated with higher levels of SO2 (lags 0-4). After correcting for multiple comparisons, the association between emergency room visits and SO2 levels was statistically significant for lag 0 (p = 0.043), lag 1 (p = 0.018), and lag 3 (p = 0.050).

CONCLUSIONS

The number of emergency room visits for exacerbation of bronchiectasis is associated with higher levels of SO2.

The cumulative effect of air pollutants on the acute exacerbation of COPD in Shanghai, China

BACKGROUND

Epidemiologic studies have shown the effect of air pollutants on acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, little is known regarding the dose-response relationship. This study aimed to investigate the cumulative effect of air pollutants on AECOPD.

METHODS

We collected 101 patients with AECOPD from November 2010 through August 2011 in Shanghai. Multiple logistic regression was used to estimate associations between air pollutants and AECOPD. Poisson regression was then applied to determine the cumulative effect of air pollutants including particulate matter 10 (PM10), PM2.5, nitrogen dioxide (NO₂), sulphur dioxide (SO₂) and ozone (O₃) on AECOPD, of which the seasonal variation was further explored.

RESULTS

The monthly episodes of AECOPD were associated with the concentrations of PM2.5 (r=0.884, p<0.05) and NO₂ (r=0.763, p<0.05). The cutoff value of PM2.5 and NO₂ for predicting AECOPD was 83.0μg/m³ and 53.5μg/m³, respectively. It showed that per 10μg/m³ increment in PM2.5 increased the relative risks (RR) for AECOPD was 1.09 with 3days cumulative effect in cold season, whereas 7days in warm season. The RR for AECOPD for per 10μg/m³ increment in NO₂ was 1.07, with a 5-day cumulative effect without seasonal variation.

CONCLUSIONS

High consecutive levels of PM2.5 and NO₂ increase the risk of developing AECOPD. Cumulative effect of PM2.5 and NO₂ appears before the exacerbation onset. These gradations were more evident in the PM2.5 during different seasons.

Keratinocytes oxidative damage mechanisms related to airbone particle matter exposure

Epidemiological evidences have correlated airbone particulate matter (PM) to adverse health effects, mainly linking to pulmonary and cardiovascular disease. Nevertheless, only recently, some studies reported detrimental effects of PM on other organs such as skin. In a recent work, we have reported increased oxidative and inflammatory responses in Reconstituted Human Epidermis (RHE) exposed to ambient particles (CAPs) and we also demonstrated the ability of CAPs to penetrate the skin tissue. The present study was aimed to better understand the cellular mechanisms beyond the oxidative changes induced by CAPs (5-10-25μg/mL) in human immortalized keratinocytes (HaCaT). After 24h of treatment, CAPs were able to enter the cells leading to a decrease in viability, increased levels of 4-hydroxinonenal products (4-HNE) and IL-1α release. Overall these data, suggest lipid and protein oxidative damage, as well as an increase of inflammatory response after being challenged with CAPs. In addition, 3h after CAPs exposure we found a significant increase in NF-kB and Nrf2 translocation into the nucleus. In contrast, no differences in gene expression and enzymatic activity of Nrf2 target genes were detected. This last finding could be explained by the ability of CAPs to possibly alter the binding of Nrf2 to the ARE DNA sequence.

Association between environmental factors and hospitalisations for bronchiectasis in Badalona, Barcelona, Spain (2007-2015)

INTRODUCTION

The relationship between environmental factors and the exacerbation of respiratory diseases has been widely studied. However, there are no studies examining the relationship between these factors and bronchiectasis exacerbations. Our objective was to analyse the association between various environmental factors and hospitalisation for bronchiectasis.

MATERIAL AND METHODS

This was a retrospective observational study conducted at two hospitals in Badalona (Barcelona). The number of hospital admissions for exacerbation of bronchiectasis between 2007 and 2015 was obtained. Through multiple regression we analysed the relationship between the number of exacerbations and mean monthly values of temperature, SO₂, NO, NO₂, O₃ and CO.

RESULTS

Temperature, SO₂, NO, NO₂, O₃ and CO were significantly associated with an increase in admissions due to exacerbation of bronchiectasis. By controlling the effect of temperature on the pollution variables, only SO₂ maintained statistical significance (P=.008).

CONCLUSION

We have detected an increase in hospital admissions for exacerbation of bronchiectasis with increases in the atmospheric concentration of SO₂ and the decrease in temperature. Prospective studies with different geographical locations to confirm these results are needed.

Autophagy Induced FHL2 Upregulation Promotes IL-6 Production by Activating the NF-κB Pathway in Mouse Aortic Endothelial Cells after Exposure to PM2.5

Epidemiological and clinical studies have increasingly shown that fine particulate matter (PM2.5) is associated with cardiovascular morbidity and mortality, which share the common feature of PM2.5-induced vascular inflammation; however, the underlying mechanisms of how PM2.5 triggers increased inflammatory response in vascular endothelial cells are not well understood. After treating mouse aortic endothelial cells (MAECs) with different concentrations of PM2.5, we assessed interleukin (IL)-6 and four and a half LIM domains 2 (FHL2) expression in cell supernatant by enzyme-linked immunosorbent assay and Western blot, respectively, as well as activation of nuclear factor (NF)-κB and immune-response signaling pathways. Additionally, changes in pathway activation, IL-6 expression, and autophagy were evaluated under PM2.5 exposure, following FHL2 knockdown with small interfering RNA. Our results indicated that PM2.5 exposure induced FHL2 expression and IL-6 secretion, as well as activation of pathways associated with immune response. Additionally, following FHL2 knockdown, the activation of NF-κB-related pathways and IL-6 secretion was inhibited under PM2.5 exposure, although the Akt- and p38-signaling pathways were not affected. Furthermore, PM2.5 exposure induced autophagy, whereas autophagy inhibition eventually inhibited PM2.5-induced FHL2 expression. These findings suggested a novel link between autophagy induced FHL2 upregulation and IL-6 production in MAECs under PM2.5 exposure.