Effects of components derived from diesel exhaust particles on lung physiology related to antigen

Differential Pattern of Cell Death and ROS Production in Human Airway Epithelial Cells Exposed to Quinones Combined with Heated-PM2.5 and/or Asian Sand Dust

The combined toxicological effects of airborne particulate matter (PM), such as PM2.5, and Asian sand dust (ASD), with surrounding chemicals, particularly quinones, on human airway epithelial cells remain underexplored. In this study, we established an in vitro combination exposure model using 1,2-naphthoquinones (NQ) and 9,10-phenanthroquinones (PQ) along with heated PM (h-PM2.5 and h-ASD) to investigate their potential synergistic effects. The impacts of quinones and heated PM on tetrazolium dye (WST-1) reduction, cell death, and cytokine and reactive oxygen species (ROS) production were examined. Results revealed that exposure to 9,10-PQ with h-PM2.5 and/or h-ASD dose-dependently increased WST-1 reduction at 1 μM compared to the corresponding control while markedly decreasing it at 10 μM. Higher early apoptotic, late apoptotic, or necrotic cell numbers were detected in 9,10-PQ + h-PM2.5 exposure than in 9,10-PQ + h-ASD or 9,10-PQ + h-PM2.5 + h-ASD. Additionally, 1,2-NQ + h-PM2.5 exposure also resulted in an increase in cell death compared to 1,2-NQ + h-ASD and 1,2-NQ + h-PM2.5 + h-ASD. Quinones with or without h-PM2.5, h-ASD, or h-PM2.5 + h-ASD significantly increased ROS production, especially with h-PM2.5. Our findings suggest that quinones, at relatively low concentrations, induce cell death synergistically in the presence of h-PM2.5 rather than h-ASD and h-PM2.5 + h-ASD, partially through the induction of apoptosis with increased ROS generation.

Air pollution significantly associated with severe ocular allergic inflammatory diseases

Ambient air pollution is a well-recognized risk for various diseases including asthma and heart diseases. However, it remains unclear whether air pollution may also be a risk of ocular allergic diseases. Using a web-based, nation-wide, cross-sectional study design, we examined whether the level of ambient air pollution is significantly associated with the prevalence of ocular allergic diseases. A web-based questionnaire was posted to invite the participants who are members of the Japan Ophthalmologist Association and their family members. The answers from 3004 respondents were used to determine whether there were significant associations between the level of the pollutants and the prevalence of ocular allergic diseases. The study period was between March to May 2017. The data of the air pollutants during 2012 to 2016 were obtained from the National Institute for Environmental Studies. The prevalence of allergic diseases was calculated by post stratification and examined for significant associations with the level of pollutants using multiple logistic regression analyses. The prevalence of seasonal allergic conjunctivitis, perennial allergic conjunctivitis, atopic keratoconjunctivitis (AKC), and vernal keratoconjunctivitis (VKC) in Japan was 45.4%, 14.0%, 5.3%, and 1.2%, respectively. The high prevalence of the severe forms of allergic conjunctivitis, including AKC and VKC, were significantly associated with the levels of the air pollutants. The prevalence of AKC was significantly associated with the levels of NO₂ with an odds ratio (OR) of 1.23 (per quintile). The prevalence of VKC was significantly associated with the levels of NO_x and PM₁₀ with ORs of 1.72 and 1.54 respectively. The significant associations between the prevalence of AKC and VKC and the levels of air pollutants indicate that clinicians need to be aware that air pollutants may pose serious risks of vision threatening severe ocular allergy.

Diesel exhausts particles: Their role in increasing the incidence of asthma. Reviewing the evidence of a causal link

Exposure to air pollutants has been correlated with an increase in the severity of asthma and in the exacerbation of pre-existing asthma. However, whether or not environmental pollution can cause asthma remains a controversial issue. The present review analyzes the current scientific evidence of the possible causal link between diesel exhaust particles (DEP), the solid fraction of the complex mixture of diesel exhaust, and asthma. The mechanisms that influence the expression and development of asthma are complex. In children prolonged exposure to pollutants such as DEPs may increase asthma prevalence. In adults, this causal relation is less clear, probably because of the heterogeneity of the studies carried out. There is also evidence of physiological mechanisms by which DEPs can cause asthma. The most frequently described interactions between cellular responses and DEP are the induction of pulmonary oxidative stress and inflammation and the activation of receptors of the bronchial epithelium such as toll-like receptors or increases in Th2 and Th17 cytokines, which generally orchestrate the asthmatic response. Others support indirect mechanisms through epigenetic changes, pulmonary microbiome modifications, or the interaction of DEP with environmental antigens to enhance their activity. However, in spite of this evidence, more studies are needed to assess the harmful effects of pollution - not only in the short term in the form of increases in the rate of exacerbations, but in the medium and long term as well, as a possible trigger of the disease.

Influences of Environmental Chemicals on Atopic Dermatitis

Atopic dermatitis is a chronic inflammatory skin condition including severe pruritus, xerosis, visible eczematous skin lesions that mainly begin early in life. Atopic dermatitis exerts a profound impact on the quality of life of patients and their families. The estimated lifetime prevalence of atopic dermatitis has increased 2~3 fold during over the past 30 years, especially in urban areas in industrialized countries, emphasizing the importance of life-style and environment in the pathogenesis of atopic diseases. While the interplay of individual genetic predisposition and environmental factors contribute to the development of atopic dermatitis, the recent increase in the prevalence of atopic dermatitis might be attributed to increased exposure to various environmental factors rather than alterations in human genome. In recent decades, there has been an increasing exposure to chemicals from a variety of sources. In this study, the effects of various environmental chemicals we face in everyday life - air pollutants, contact allergens and skin irritants, ingredients in cosmetics and personal care products, and food additives - on the prevalence and severity of atopic dermatitis are reviewed.

A toxicology suite adapted for comparing parallel toxicity responses of model human lung cells to diesel exhaust particles and their extracts

Epidemiological studies have shown that exposure to airborne particulate matter can be an important risk factor for some common respiratory diseases. While many studies have shown that particulate matter exposures are associated with inflammatory reactions, the role of specific cellular responses in the manifestation of primary hypersensitivities, and the progression of respiratory diseases remains unclear. In order to better understand mechanisms by which particulate matter can exert adverse health effects, more robust approaches to support in vitro studies are warranted. In response to this need, a group of accepted toxicology assays were adapted to create an analytical suite for screening and evaluating the effects of important, ubiquitous atmospheric pollutants on two model human lung cell lines (epithelial and immature macrophage). To demonstrate the utility of this suite, responses to intact diesel exhaust particles, and mass-based equivalent doses of their organic extracts were examined. Results suggest that extracts have the potential to induce greater biological responses than those associated with their colloidal counterpart. Additionally, macrophage cells appear to be more susceptible to the cytotoxic effects of both intact diesel exhaust particles and their organic extract, than epithelial cells tested in parallel. As designed, the suite provided a more robust basis for characterizing toxicity mechanisms than the analysis of any individual assay. Findings suggest that cellular responses to particulate matter are cell line dependent, and show that the collection and preparation of PM and/or their extracts have the potential to impact cellular responses relevant to screening fundamental elements of respiratory toxicity.

Environmental effects on immune responses in patients with atopy and asthma

Despite attempts and some successes to improve air quality over the decades, current US national trends suggest that exposure to outdoor and indoor air pollution remains a significant risk factor for both the development of asthma and the triggering of asthma symptoms. Emerging science also suggests that environmental exposures during the prenatal period and early childhood years increase the risk of asthma. Multiple mechanisms mediate this risk because a wide range of deleterious air pollutants contribute to the pathogenesis of asthma across a variety of complex asthma phenotypes. In this review we will consider the role of altered innate and adaptive immune responses, gene-environment interactions, epigenetic regulation, and possibly gene-environment-epigene interactions. Gaining a greater understanding of the mechanisms that underlie the effect of exposure to air pollution on asthma, allergies, and other airway diseases can identify targets for therapy. Such interventions will include pollutant source reduction among those most exposed and most vulnerable and novel pharmaceutical strategies to reduce asthma morbidity.

IL-17A is essential to the development of elastase-induced pulmonary inflammation and emphysema in mice

Background

Pulmonary emphysema is characterized by alveolar destruction and persistent inflammation of the airways. Although IL-17A contributes to many chronic inflammatory diseases, it’s role in the inflammatory response of elastase-induced emphysema remains unclear.

Methods

In a model of elastase-induced pulmonary emphysema we examined the response of IL-17A-deficient mice, monitoring airway inflammation, static compliance, lung histology and levels of neutrophil-related chemokine and pro-inflammatory cytokines in bronchoalveolar lavage (BAL) fluid.

Results

Wild-type mice developed emphysematous changes in the lung tissue on day 21 after elastase treatment, whereas emphysematous changes were decreased in IL-17A-deficient mice compared to wild-type mice. Neutrophilia in BAL fluid, seen in elastase-treated wild-type mice, was reduced in elastase-treated IL-17A-deficient mice on day 4, associated with decreased levels of KC, MIP-2 and IL-1 beta. Elastase-treated wild-type mice showed increased IL-17A levels as well as increased numbers of IL-17A+ CD4 T cells in the lung in the initial period following elastase treatment.

Conclusions

These data identify the important contribution of IL-17A in the development of elastase-induced pulmonary inflammation and emphysema. Targeting IL-17A in emphysema may be a potential therapeutic strategy for delaying disease progression.

Traffic-related particulate matter and acute respiratory symptoms among New York City area adolescents

BACKGROUND

Exposure to traffic-related particulate matter (PM) has been associated with adverse respiratory health outcomes in children. Diesel exhaust particles (DEPs) are a local driver of urban fine PM [aerodynamic diameter < or = 2.5 microm (PM(2.5))]; however, evidence linking ambient DEP exposure to acute respiratory symptoms is relatively sparse, and susceptibilities of urban and asthmatic children are inadequately characterized.

OBJECTIVES

We examined associations of daily ambient black carbon (BC) concentrations, a DEP indicator, with daily respiratory symptoms among asthmatic and nonasthmatic adolescents in New York City (NYC) and a nearby suburban community.

METHODS

BC and PM(2.5) were monitored continuously outside three NYC high schools and one suburban high school for 4-6 weeks, and daily symptom data were obtained from 249 subjects (57 asthmatics, 192 nonasthmatics) using diaries. Associations between pollutants and symptoms were characterized using multilevel generalized linear mixed models, and modification by urban residence and asthma status were examined.

RESULTS

Increases in BC were associated with increased wheeze, shortness of breath, and chest tightness. Multiple lags of nitrogen dioxide (NO(2)) exposure were associated with symptoms. For several symptoms, associations with BC and NO(2) were significantly larger in magnitude among urban subjects and asthmatics compared with suburban subjects and nonasthmatics, respectively. PM(2.5) was not consistently associated with increases in symptoms.

CONCLUSIONS

Acute exposures to traffic-related pollutants such as DEPs and/or NO(2) may contribute to increased respiratory morbidity among adolescents, and urban residents and asthmatics may be at increased risk. The findings provide support for developing additional strategies to reduce diesel emissions further, especially in populations susceptible because of environment or underlying respiratory disease.

Extensive Analysis of Elastase-Induced Pulmonary Emphysema in Rats: ALP in the Lung, a New Biomarker for Disease Progression?

It is accepted that pulmonary exposure of rodents to porcine pancreatic elastase (ELT) induces lesions that morphologically resemble human emphysema. Nonetheless, extensive analysis of this model has rarely been conducted. The present study was designed to extensively examine the effects of ELT on lung inflammation, cell damage, emphysematous change, and cholinergic reactivity in rats. Intratracheal administration of two doses of ELT induced 1) a proinflammatory response in the lung that was characterized by significant infiltration of macrophages and an increased level of interleukin-1beta in lung homogenates, 2) lung cell damage as indicated by higher levels of total protein, lactate dehydrogenase, and alkaline phosphatase (ALP) in lung homogenates, 3) emphysema-related morphological changes including airspace enlargement and progressive destruction of alveolar wall structures, and 4) airway responsiveness to methacholine including an augmented Rn value. In addition, ELT at a high dose was more effective than that at a low dose. This is the novel study to extensively analyze ELT-induced lung emphysema, and the analysis might be applied to future investigations that evaluate new therapeutic agents or risk factors for pulmonary emphysema. In particular, ALP in lung homogenates might be a new biomarker for the disease progression/exacerbation.

Peroxiredoxin I is a negative regulator of Th2-dominant allergic asthma

Peroxiredoxin (Prx) I, a ubiquitous antioxidant enzyme, is known to protect against inflammation; however, its role in the allergic inflammation remains unidentified. We determined whether intristic Prx I protects against allergic asthma traits using Prx-I knockout (-/-) mice. Prx I (-/-) and wild-type (WT) mice were immunized with ovalbumin (OVA) plus aluminum potassium sulfate (Alum: Th2 adjuvant) and subsequently challenged with OVA. Twenty-four hours after the last OVA challenge, leukocyte influx including eosinophils into bronchoalveolar lavage fluid was significantly greater in Prx I (-/-) mice compared to that in WT mice. On the other hand, when these mice were immunized with OVA+complete Freund's adjuvant (Th1 adjuvant), opposite phenomenon was observed. In the presence of OVA/Alum, peribronchial inflammatory leukocyte infiltration, cholinergic airway resistance, and the lung expression of interleukin (IL)-2 were significantly greater and that of interferon-gamma was significantly lesser in Prx I (-/-) than in WT mice. In vitro, OVA/Alum-sensitized Prx I (-/-) T cells proliferated more profoundly than WT T cells when they were cocultured with syngeneic bone marrow-generated dendritic cells. These results indicate that endogenous Prx I protects against allergen-related Th2-type airway inflammation and hyperresponsiveness, at least partly, via the suppression of the lung expression of IL-2 and regulation of the Th1/Th2 balance in addition to its antioxidative properties. Furthermore, Prx I can inhibit allergen-specific T-cell proliferation through immunological synapse. Our findings implicate an alternative therapeutic value of Prx I in the treatment of Th2-skewed allergic airway inflammatory diseases such as atopic asthma.

Air pollution and childhood asthma: recent advances and future directions

PURPOSE OF REVIEW

Current levels of air pollution are consistently associated with asthma development and morbidity among children, suggesting that current regulatory policies may be insufficient. This review will describe recent studies that have examined specific emission sources or components of pollutants that may be associated with pediatric asthma and identify subpopulations that may be particularly susceptible to the effects of air pollution exposure.

RECENT FINDINGS

Important advances include new characterizations of the effects of traffic-related air pollution in urban areas. They also include the application of novel exposure and outcome measures such as pollution estimates derived from land use regression modeling and biological markers of airway inflammation. Additionally, studies have identified host susceptibility characteristics that may modify responses to air pollution exposure, including polymorphisms in oxidative stress genes and epigenetic alterations.

SUMMARY

Identifying specific sources and toxic constituents of air pollution and accurately assessing air pollutant-related asthma outcomes are needed to better direct control strategies. Further research is needed to identify additional host factors that confer increased susceptibility to air pollution exposure. Future therapy to reduce the adverse effects of air pollution on respiratory disease will likely depend on targeting susceptible populations for intervention.

Oxidants and the pathogenesis of lung diseases

The increasing number of population-based and epidemiologic associations between oxidant pollutant exposures and cardiopulmonary disease exacerbation, decrements in pulmonary function, and mortality underscores the important detrimental effects of oxidants on public health. Because inhaled oxidants initiate a number of pathologic processes, including inflammation of the airways, which may contribute to the pathogenesis and/or exacerbation of airways disease, it is critical to understand the mechanisms through which exogenous and endogenous oxidants interact with molecules in the cells, tissues, and epithelial lining fluid of the lung. Furthermore, it is clear that interindividual variation in response to a given exposure also exists across an individual lifetime. Because of the potential impact that oxidant exposures may have on reproductive outcomes and infant, child, and adult health, identification of the intrinsic and extrinsic factors that may influence susceptibility to oxidants remains an important issue. In this review, we discuss mechanisms of oxidant stress in the lung, the role of oxidants in lung disease pathogenesis and exacerbation (eg, asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome), and the potential risk factors (eg, age, genetics) for enhanced susceptibility to oxidant-induced disease.