Biochemical effects of ozone on asthma during postnatal development

Ozone in the Development of Pediatric Asthma and Atopic Disease

Ozone (O3) is a ubiquitous outdoor air pollutant, which may be derived from various primary pollutants such as nitrates, hydrocarbons, and volatile organ compounds through ultraviolet radiation exposure, and has been shown to negatively impact respiratory health. O3 is the most common noninfectious environmental cause of asthma exacerbations among children and adults. Its effects on pediatric respiratory health could be due to multiple physiologic factors that may contribute to enhanced O3 exposure seen in children compared with adults, including differences in lung surface area per unit of body weight and ventilation rates. O3 can reach the distal regions of human lungs due to its low water solubility, resulting in either injury or activation of airway epithelial cells and macrophages. Multiple epidemiologic studies have highlighted a link between exposure to air pollution and the development of asthma. This review article specifically focuses on examining the impact of early life O3 exposure on lung development, lung function, and the risk of developing atopic diseases including asthma, allergic rhinitis, and atopic dermatitis among children.

Daily Mortality in Different Age Groups Associated with Exposure to Particles, Nitrogen Dioxide and Ozone in Two Northern European Capitals: Stockholm and Tallinn

Although the association between air pollution and mortality is well established, less is known about the effects in different age groups. This study analyzes the short-term associations between mortality in different age groups (0–14 years of age, 15–64 years of age, and 65+ years of age) and a number of air pollutants in two relatively clean northern European capitals: Stockholm and Tallinn. The concentrations in PM10 (particles with an aerodynamic diameter smaller than or equal to 10 µm), PM2.5–10 (coarse particles), PM2.5 (particles with an aerodynamic diameter smaller than or equal to 2.5 µm), BC (black carbon), PNC4 (particle number count of particles larger than or equal to 4 nm), NO2 (nitrogen dioxide), and O3 (ozone) were measured during the period of 2000–2016 in Stockholm and 2001–2018 in Tallinn (except for BC and PNC4 which were only measured in Stockholm). The excess risks in daily mortality associated with an interquartile range (IQR) increase in the measured air pollutants were calculated in both single- and multi-pollutant models for lag01 and lag02 (average concentration during the same and the previous day, and the same and the previous two days, respectively) using a quasi-Poisson regression model with a logistic link function. In general, the calculated excess risks per IQR increase were highest in the age group 0–14 years of age in both Stockholm and Tallinn. However, in Stockholm, a statistically significant effect was shown for PM2.5–10, and in Tallinn for O3. In the oldest age group (65+), statistically significant effects were shown for both PM2.5–10, PM10, and O3 in Stockholm, and for O3 in Tallinn.

Critical review of long-term ozone exposure and asthma development

Asthma, a chronic respiratory disorder with complex etiology and various phenotypes, is a considerable public health concern in the USA and worldwide. While there is evidence suggesting ambient ozone exposure may exacerbate asthma, information regarding the potential role of ozone in asthma development is more limited. Thus, we conducted a critical review of observational epidemiology studies to determine whether long-term ambient ozone exposure is a risk factor for asthma development. We identified 14 relevant studies; 11 evaluated asthma development in children, while three studies, based on a single cohort, assessed this outcome in adults. Studies of childhood asthma and long-term ozone exposure - including exposure in utero, during the first year of life and during early childhood - reported inconsistent findings, which were further weakened by critical methodological limitations in statistical analyses and in exposure and outcome assessments, such as exposure measurement error and a lack of adjustment for key confounders. For adult-onset asthma, long-term ozone exposure was associated with an increased risk in men but not women. In addition to considerable uncertainties due to potential exposure measurement error and a lack of adjustment for key confounders, this study has limited generalizability to the US general population. While experimental evidence indicates that it may be biologically plausible that long-term ozone exposure could contribute to asthma development, it does not provide insight regarding an established mode of action. Future research is needed to address the uncertainties regarding the role of long-term ambient ozone exposure in asthma development.

IL-17A Monoclonal Antibody Partly Reverses the Glucocorticoids Insensitivity in Mice Exposed to Ozonec

Exposure to ozone has been associated with airway inflammation and glucocorticoid insensitivity. This study aimed to observe the capacity of anti-murine interleukin-17A monoclonal antibody (IL-17mAb) to reverse ozone-induced glucocorticoid insensitivity and to detect its effects with glucocorticoids in protecting against airway inflammation. After C57/BL6 mice were exposed to ozone (2.5 ppm; 3 h) for 12 times over 6 weeks, PBS, IL-17mAb (50 ug/ml), dexamethasone (2 mg/kg), and combination administration of IL-17mAb (50 ug/ml) and dexamethasone (2 mg/kg) were intraperitoneally injected into mice at a dose of 0.1 ml, respectively, for 10 times over 5 weeks. At sacrifice, lung histology, airway inflammatory cells, levels of related cytokines in bronchoalveolar lavage fluid (BALF), and serum were analyzed, airway inflammatory cell infiltration density and mean linear intercept (Lm) were measured, the expression of IL-17A mRNA, glucocorticoid receptors (GR), NF-κB, and p38 mitogen-activated protein kinase (MAPK) phosphorylation were determined. We found that combination administration markedly reduced ozone-induced total inflammatory cells, especially neutrophils; inhibited levels of cytokines, including IL-8, IL-17A, and TNF-α in BALF; and suppressed airway inflammatory cell infiltration density and Lm. Additionally, combination administration significantly elevated levels of IFN-γ in BALF, decreased the dexamethasone-induced increase of IL-17A mRNA, and increased the expression of GR and decrement of NF-κB and p38MAPK phosphorylation, which are also related to glucocorticoids insensitivity. Collectively, combination administration shows profound efficacy in inhibiting certain cytokines, and IL-17 mAb partly improved the glucocorticoids insensitivity via modulating the enhanced production rate and improving expression of IL-17A induced by glucocorticoids administration and p38MAPK, NF-κB signaling pathway.

Multiple Threats to Child Health from Fossil Fuel Combustion: Impacts of Air Pollution and Climate Change

BACKGROUND

Approaches to estimating and addressing the risk to children from fossil fuel combustion have been fragmented, tending to focus either on the toxic air emissions or on climate change. Yet developing children, and especially poor children, now bear a disproportionate burden of disease from both environmental pollution and climate change due to fossil fuel combustion.

OBJECTIVE

This commentary summarizes the robust scientific evidence regarding the multiple current and projected health impacts of fossil fuel combustion on the young to make the case for a holistic, child-centered energy and climate policy that addresses the full array of physical and psychosocial stressors resulting from fossil fuel pollution.

DISCUSSION

The data summarized here show that by sharply reducing our dependence on fossil fuels we would achieve highly significant health and economic benefits for our children and their future. These benefits would occur immediately and also play out over the life course and potentially across generations.

CONCLUSION

Going beyond the powerful scientific and economic arguments for urgent action to reduce the burning of fossil fuels is the strong moral imperative to protect our most vulnerable populations. Citation: Perera FP. 2017. Multiple threats to child health from fossil fuel combustion: impacts of air pollution and climate change. Environ Health Perspect 125:141-148; http://dx.doi.org/10.1289/EHP299.

Role of neutralizing anti-murine interleukin-17A monoclonal antibody on chronic ozone-induced airway inflammation in mice

Exposure to ozone has led to airway inflammation and airway hyperresponsiveness, which potential mechanisms relate to ozone-induced oxidative stress. IL-17 is a growing target for autoimmune and inflammatory diseases. The aim of the study was to examine the inhibitory effects of anti-murine interleukin-17A monoclonal antibody (IL-17mAb) on adverse effects of ozone which are noted above. After C57/BL6 mice were exposed to ozone (2.5ppm; 3h) for 12 times over 6 weeks, IL-17mAb, PBS was intraperitoneally injected into mice 1h after ozone or air exposure for 6 weeks and mice were studied 24h after final exposure, monitoring bronchial responsiveness, airway inflammatory cells, lung histology, levels of neutrophil-related chemokine and proinflammatory cytokines in bronchoalveolar lavage (BAL) fluid and serum, the expression of IL-17A mRNA and protein, glucocorticoid receptors (GR), and the phosphorylation of p38MAPK in lung tissues. The administration of IL-17mAb reduced the ozone-induced increases in total cells, especially neutrophils; decreased levels of cytokines, including IL-8 in BAL fluid, IL-8 and IL-17A in serum; mitigated the severity of airway hyperresponsiveness; attenuated lung inflammation scores and histologic analysis confirmed the suppression of lung inflammation, compared with the administration of a control PBS. Exposure to ozone results in increases in IL-17A production rate, mRNA and protein levels of IL-17A and the protein level of GR. These effects were halted and reversed by IL-17mAb treatment. Furthermore, IL-17mAb also reduced the phosphorylation of p38MAPK. Therefore, we conclude that IL-17mAb may be a useful therapy in ozone-related diseases, including COPD.

The lung response to ozone is determined by age and is partially dependent on toll-Like receptor 4

Background

Ozone pollution has adverse effects on respiratory health in children and adults. This study was carried out in the mouse model to investigate the influence of age and to define the role of toll-like receptor four (TLR4) in the lung response to ozone exposure during postnatal development.

Methods

Female mice (1 to 6 weeks of age) were exposed for 3 h to ozone (1 part per million) or filtered air. Analyses were carried out at six and 24 h after completion of exposure, to assess the effects on lung permeability, airway neutrophilia, expression of antioxidants and chemokines, and mucus production. The role of TLR4 was defined by examining TLR4 expression in the lung during development, and by investigating the response to ozone in tlr4-deficient mice.

Results

Metallothionein-1, calcitonin gene-related product, and chemokine C-X-C ligand (CXCL) five were consistent markers induced by ozone throughout development. Compared with adults, neonates expressed lower levels of pulmonary TLR4 and responded with increased mucus production, and developed an attenuated response to ozone characterized by reduced albumin leakage and neutrophil influx into the airways, and lower expression of CXCL1 and CXCL2 chemokines. Examination of the responses in tlr4-deficient mice indicated that ozone-mediated airway neutrophilia, but not albumin leakage or mucus production were dependent on TLR4.

Conclusions

Collectively, the data demonstrate that the response to ozone is determined by age and is partially dependent on TLR4 signaling. The reduced responsiveness of the neonatal lung to ozone may be due at least in part to insufficient pulmonary TLR4 expression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0279-2) contains supplementary material, which is available to authorized users.

Inhibitory effect of hydrogen sulfide on ozone-induced airway inflammation, oxidative stress, and bronchial hyperresponsiveness

Exposure to ozone has been associated with airway inflammation, oxidative stress, and bronchial hyperresponsiveness. The goal of this study was to examine whether these adverse effects of ozone could be prevented or reversed by hydrogen sulfide (H2S) as a reducing agent. The H2S donor sodium (NaHS) (2 mg/kg) or vehicle (PBS) was intraperitoneally injected into mice 1 hour before and after 3-hour ozone (2.5 ppm) or air exposure, and the mice were studied 24 hours later. Preventive and therapeutic treatment with NaHS reduced the ozone-induced increases in the total cells, including neutrophils and macrophages; this treatment also reduced levels of cytokines, including TNF-α, chemokine (C-X-C motif) ligand 1, IL-6, and IL-1β levels in bronchial alveolar lavage fluid; inhibited bronchial hyperresponsiveness; and attenuated ozone-induced increases in total malondialdehyde in bronchoalveolar lavage fluid and decreases in the ratio of reduced glutathione/oxidized glutathione in the lung. Ozone exposure led to decreases in the H2S production rate and in mRNA and protein levels of cystathionine-β-synthetase and cystathionine-γ-lyase in the lung. These effects were prevented and reversed by NaHS treatment. Furthermore, NaHS prevented and reversed the phosphorylation of p38 mitogen-activated protein kinase and heat shock protein 27. H2S may have preventive and therapeutic value in the treatment of airway diseases that have an oxidative stress basis.

Reprint of: Perinatal and early childhood environmental factors influencing allergic asthma immunopathogenesis

BACKGROUND

The prevalence of asthma has increased dramatically over the past several decades. While hereditary factors are highly important, the rapid rise outstrips the pace of genomic variation. Great emphasis has been placed on potential modifiable early life exposures leading to childhood asthma.

METHODS

We reviewed the recent medical literature for important studies discussing the role of the perinatal and early childhood exposures and the inception of childhood asthma.

RESULTS AND DISCUSSION

Early life exposure to allergens (house dust mite (HDM), furred pets, cockroach, rodent and mold), air pollution (nitrogen dioxide (NO2), ozone (O3), volatile organic compounds (VOCs), and particulate matter (PM)) and viral respiratory tract infections (Respiratory syncytial virus (RSV) and human rhinovirus (hRV)) has been implicated in the development of asthma in high risk children. Conversely, exposure to microbial diversity in the perinatal period may diminish the development of atopy and asthma symptoms.

Perinatal and early childhood environmental factors influencing allergic asthma immunopathogenesis

BACKGROUND

The prevalence of asthma has increased dramatically over the past several decades. While hereditary factors are highly important, the rapid rise outstrips the pace of genomic variation. Great emphasis has been placed on potential modifiable early life exposures leading to childhood asthma.

METHODS

We reviewed the recent medical literature for important studies discussing the role of the perinatal and early childhood exposures and the inception of childhood asthma.

RESULTS AND DISCUSSION

Early life exposure to allergens (house dust mite (HDM), furred pets, cockroach, rodent and mold), air pollution (nitrogen dioxide (NO(2)), ozone (O(3)), volatile organic compounds (VOCs), and particulate matter (PM)) and viral respiratory tract infections (Respiratory syncytial virus (RSV) and human rhinovirus (hRV)) has been implicated in the development of asthma in high risk children. Conversely, exposure to microbial diversity in the perinatal period may diminish the development of atopy and asthma symptoms.

Irreversible airway obstruction in asthma: what we lose, we lose early

Asthma, a syndrome manifested by airway inflammation and obstruction, globally contributes significantly to morbidity and mortality. Although current evidence identifies risk factors that evoke asthma, critical questions concerning susceptibility factors that induce severe persistent disease remain unclear. Early onset of asthma decreases lung function that may be unrecognized until later in adulthood when patients experience dyspnea on exertion and attenuated quality of life. This review highlights current evidence in predicting the onset of asthma and identifying those patients at greatest risk for severe persistent disease.

A review on human health perspective of air pollution with respect to allergies and asthma

The increase in cases of asthma and allergies has become an important health issue throughout the globe. Although these ailments were not common diseases a few short decades ago, they are now affecting a large part of the population in many regions. Exposure to environmental (both outdoor and indoor) pollutants may partially account for the prevalence of such diseases. In this review, we provide a multidisciplinary review based on the most up-to-date survey of literature regarding various types of airborne pollutants and their associations with asthma-allergies. The major pollutants in this respect include both chemical (nitrogen dioxide, ozone, sulfur dioxide, particulate matter, and volatile organic compounds) and biophysical parameters (dust mites, pet allergens, and mold). The analysis was extended further to describe the development of these afflictions in the human body and the subsequent impact on health. This publication is organized to offer an overview on the current state of research regarding the significance of air pollution and its linkage with allergy and asthma.