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

The respiratory health effects of acute in vivo diesel and biodiesel exhaust in a mouse model

BACKGROUND

Biodiesel, a renewable diesel fuel that can be created from almost any natural fat or oil, is promoted as a greener and healthier alternative to commercial mineral diesel without the supporting experimental data to back these claims. The aim of this research was to assess the health effects of acute exposure to two types of biodiesel exhaust, or mineral diesel exhaust or air as a control in mice. Male BALB/c mice were exposed for 2-hrs to diluted exhaust obtained from a diesel engine running on mineral diesel, Tallow biodiesel or Canola biodiesel. A room air exposure group was used as a control. Twenty-four hours after exposure, a variety of respiratory related end point measurements were assessed, including lung function, responsiveness to methacholine and airway and systemic immune responses.

RESULTS

Tallow biodiesel exhaust exposure resulted in the greatest number of significant effects compared to Air controls, including increased airway hyperresponsiveness (178.1 ± 31.3% increase from saline for Tallow biodiesel exhaust exposed mice compared to 155.8 ± 19.1 for Air control), increased airway inflammation (63463 ± 13497 cells/mL in the bronchoalveolar lavage of Tallow biodiesel exhaust exposed mice compared to 40561 ± 11800 for Air exposed controls) and indications of immune dysregulation. In contrast, exposure to Canola biodiesel exhaust resulted in fewer significant effects compared to Air controls with a slight increase in airway resistance at functional residual capacity and indications of immune dysregulation. Exposure to mineral diesel exhaust resulted in significant effects between that of the two biodiesels with increased airway hyperresponsiveness and indications of immune dysregulation.

CONCLUSION

These data show that a single, brief exposure to biodiesel exhaust can result in negative health impacts in a mouse model, and that the biological effects of exposure change depending on the feedstock used to make the biodiesel.

The Impact of the Reduction in Environmental Pollution during COVID-19 Lockdown on Healthy Individuals

The lockdown imposed to combat the COVID-19 pandemic produced a historic fall in air pollution in cities like Barcelona. This exceptional situation offered a unique context in which to examine the effects of air pollutants on human health. The present study aims to determine and compare the oxidative stress biomarkers Th1/Th2 and inflammatory-related cytokines in healthy individuals first during lockdown and then six months after the easing of the restrictions on mobility. A prospective study of a representative sample of 58 healthy, non-smoking adults was carried out. During lockdown and six months post-easing of restrictions, blood samples were drawn to measure the percentage of eosinophils, levels of Th1/Th2 and inflammatory-related cytokines assessed by a multiplex assay (BioRad Laboratories S.A., Marnes-la-Coquette, France), and levels of 8-isoprostane, glutathione peroxidase activity, and myeloperoxidase (Cayman Chemical Co., Ann Arbor, MI, USA), to assess their value as biomarkers of oxidative stress. Six months after easing mobility restrictions, increases in the levels of 8-isoprostane (p < 0.0001), IL-1β (p = 0.0013), IL-1ra (p = 0.0110), IL-4 (p < 0.0001), IL-13 (p < 0.0001), G-CSF (p = 0.0007), and CCL3 (p < 0.0001) were recorded, along with reductions in glutathione peroxidase (p < 0.0001), IFN-γ (p = 0.0145), TNFα (p < 0.0001), IP-10 (p < 0.0001), IL-2 (p < 0.0001), IL-7 (p < 0.0001), basic FGF (p < 0.0001), CCL4 (p < 0.0001), and CCL5 (p < 0.0001). No significant differences were observed in the rest of the biomarkers analyzed. The reduction in environmental pollution during the COVID-19 lockdown significantly lowered the levels of oxidative stress, systemic inflammation, and Th2-related cytokines in healthy people.

Impacts of ambient air quality on acute asthma hospital admissions during the COVID-19 pandemic in Oxford City, UK: a time-series study

OBJECTIVES

The study aims to investigate the short-term associations between exposure to ambient air pollution (nitrogen dioxide (NO2), particulate matter pollution-particles with diameter<2.5 µm (PM2.5) and PM10) and incidence of asthma hospital admissions among adults, in Oxford, UK.

DESIGN

Retrospective time-series study.

SETTING

Oxford City (postcode areas OX1-OX4), UK.

PARTICIPANTS

Adult population living within the postcode areas OX1-OX4 in Oxford, UK from 1 January 2015 to 31 December 2021.

PRIMARY AND SECONDARY OUTCOME MEASURES

Hourly NO2, PM2.5 and PM10 concentrations and meteorological data for the period 1 January 2015 to 31 December 2020 were analysed and used as exposures. We used Poisson linear regression analysis to identify independent associations between air pollutant concentrations and asthma admissions rate among the adult study population, using both single (NO2, PM2.5, PM10) and multipollutant (NO2 and PM2.5, NO2 and PM10) models, where they adjustment for temperature and relative humidity.

RESULTS

The overall 5-year average asthma admissions rate was 78 per 100 000 population during the study period. The annual average rate decreased to 46 per 100 000 population during 2020 (incidence rate ratio 0.58, 95% CI 0.42 to 0.81, p<0.001) compared to the prepandemic years (2015-2019). In single-pollutant analysis, we observed a significantly increased risk of asthma admission associated with each 1 μg/m3 increase in monthly concentrations of NO2 4% (95% CI 1.009% to 1.072%), PM2.5 3% (95% CI 1.006% to 1.052%) and PM10 1.8% (95% CI 0.999% to 1.038%). However, in the multipollutant regression model, the effect of each individual pollutant was attenuated.

CONCLUSIONS

Ambient NO2 and PM2.5 air pollution exposure increased the risk of asthma admissions in this urban setting. Improvements in air quality during COVID-19 lockdown periods may have contributed to a substantially reduced acute asthma disease burden. Large-scale measures to improve air quality have potential to protect vulnerable people living with chronic asthma in urban areas.

The East Bay Diesel Exposure Project: a biomonitoring study of parents and their children in heavily impacted communities

BACKGROUND

Diesel exhaust (DE) exposures pose concerns for serious health effects, including asthma and lung cancer, in California communities burdened by multiple stressors.

OBJECTIVE

To evaluate DE exposures in disproportionately impacted communities using biomonitoring and compare results for adults and children within and between families.

METHODS

We recruited 40 families in the San Francisco East Bay area. Two metabolites of 1-nitropyrene (1-NP), a marker for DE exposures, were measured in urine samples from parent-child pairs. For 25 families, we collected single-day spot urine samples during two sampling rounds separated by an average of four months. For the 15 other families, we collected daily spot urine samples over four consecutive days during the two sampling rounds. We also measured 1-NP in household dust and indoor air. Associations between urinary metabolite levels and participant demographics, season, and 1-NP levels in dust and air were evaluated.

RESULTS

At least one 1-NP metabolite was present in 96.6% of the urine samples. Detection frequencies for 1-NP in dust and indoor air were 97% and 74%, respectively. Results from random effect models indicated that levels of the 1-NP metabolite 6-hydroxy-1-nitropyrene (6-OHNP) were significantly higher in parents compared with their children (p-value = 0.005). Urinary 1-NP metabolite levels were generally higher during the fall and winter months. Within-subject variability was higher than between-subject variability (~60% of total variance versus ~40%, respectively), indicating high short-term temporal variability.

IMPACT

Biomonitoring, coupled with air monitoring, improves understanding of hyperlocal air pollution impacts. Results from these studies will inform the design of effective exposure mitigation strategies in disproportionately affected communities.

A multi-residue method for the analysis of organic pollutants released from atmospheric PM2.5 in simulated biological fluids: Inhalation bioaccessibility and bioavailability estimation

BACKGROUND

In recent decades, there has been a growing interest within the scientific community regarding the study of the fraction that could be released in simulated biological fluids to estimate in vitro bioaccessibility and bioavailability of compounds. Concerning particulate matter (PM), studies were essentially focused on metal (oid)s probably due to more complex methodologies needed for organic compounds, requiring extraction and pre-concentration steps from simulated fluids, followed by chromatographic analysis. Thus, the development of a simple and sensitive methodology for the analysis of multi-class organic compounds released in different inhalation simulated fluids would represent a great contribution to the field.

RESULTS

In this work, a methodology for the analysis of 49 organic pollutants, including 18 polycyclic aromatic hydrocarbons (PAHs), 12 phthalate esters (PAEs), 11 organophosphorus flame retardants (OPFRs), 6 synthetic musk compounds (SMCs) and 2 bisphenols released in simulated fluids from PM2.5 samples was developed. After a physiologically based extraction test (PBET) by using artificial lysosomal fluid (ALF) and a simulated body fluid (SBF, filling a dialysis membrane) to obtain in vitro inhalation bioaccessible and bioavailable fractions, respectively; compounds were determined by a vortex-assisted liquid-liquid extraction (VALLE) and a subsequent analysis by programmed temperature vaporization-gas chromatography-tandem mass spectrometry (PTV-GC-MS/MS). Experimental conditions concerning VALLE extraction (extraction time and amount of NaCl (g)) were optimized by using a central composite design (CCD), best MS/MS transitions were selected and matrix-matched calibration combined with use of labelled subrogate standards provided high sensitivity, minimization of matrix effects and recovering losses compensation.

SIGNIFICANCE

The successful validation results obtained for most of the compounds demonstrated the effectiveness of the proposed methodology for the analysis of multi-class organic pollutants released in ALF and SBF for inhalation bioaccessibility and bioavailability assessment, respectively. Furthermore, applicability of the method was proved by analysing 20 p.m.2.5 samples, being the proposed in vitro PBET dialyzability approach for assessing organic pollutant's inhalation bioavailability applied to PM2.5 samples for the first time.

Concentration-dependent increase in symptoms due to diesel exhaust in a controlled human exposure study

Background

Traffic-related air pollution (TRAP) exposure causes adverse effects on wellbeing and quality of life, which can be studied non-invasively using self-reported symptoms. However, little is known about the effects of different TRAP concentrations on symptoms following controlled exposures, where acute responses can be studied with limited confounding. We investigated the concentration–response relationship between diesel exhaust (DE) exposure, as a model TRAP, and self-reported symptoms.

Methods

We recruited 17 healthy non-smokers into a double-blind crossover study where they were exposed to filtered air (FA) and DE standardized to 20, 50, 150 µg/m3 PM2.5 for 4 h, with a ≥ 4-week washout between exposures. Immediately before, and at 4 h and 24 h from the beginning of the exposure, we administered visual analog scale (VAS) questionnaires and grouped responses into chest, constitutional, eye, neurological, and nasal categories. Additionally, we assessed how the symptom response was related to exposure perception and airway function.

Results

An increase in DE concentration raised total (β ± standard error = 0.05 ± 0.03, P = 0.04), constitutional (0.01 ± 0.01, P = 0.03) and eye (0.02 ± 0.01, P = 0.05) symptoms at 4 h, modified by perception of temperature, noise, and anxiety. These symptoms were also correlated with airway inflammation. Compared to FA, symptoms were significantly increased at 150 µg/m3 for the total (8.45 ± 3.92, P = 0.04) and eye (3.18 ± 1.55, P = 0.05) categories, with trends towards higher values in the constitutional (1.49 ± 0.86, P = 0.09) and nasal (1.71 ± 0.96, P = 0.08) categories.

Conclusion

DE exposure induced a concentration-dependent increase in symptoms, primarily in the eyes and body, that was modified by environmental perception. These observations emphasize the inflammatory and sensory effects of TRAP, with a potential threshold below 150 µg/m3 PM2.5. We demonstrate VAS questionnaires as a useful tool for health monitoring and provide insight into the TRAP concentration–response at exposure levels relevant to public health policy.

DEPs Induce Local Ige Class Switching Independent of Their Ability to Stimulate iBALT de Novo Formation

BACKGROUND

Diesel exhaust particles (DEPs) are leading to a general increase in atopic diseases worldwide. However, it is still unknown whether DEPs induce systemic B-cell IgE class switching in secondary lymphoid organs or locally in the lungs in inducible bronchus-associated lymphoid tissue (iBALT). The aim of this work was to identify the exact site of DEP-mediated B-cell IgE class switching and pro-allergic antibody production.

METHODS

We immunized BALB/c mice with different OVA doses (0.3 and 30 µg) intranasally in the presence and absence of two types of DEPs, SRM1650B and SRM2786. We used low (30 µg) and high (150 µg) DEP doses.

RESULTS

Only a high DEP dose induced IgE production, regardless of the particle type. Local IgE class switching was stimulated upon treatment with both types of particles with both low and high OVA doses. Despite the similar ability of the two standard DEPs to stimulate IgE production, their ability to induce iBALT formation and growth was markedly different upon co-administration with low OVA doses.

CONCLUSIONS

DEP-induced local IgE class switching takes place in preexisting iBALTs independent of de novo iBALT formation, at least in the case of SRM1650B co-administered with low OVA doses.

Therapeutic Efficacy of Weissella cibaria CMU and CMS1 on Allergic Inflammation Exacerbated by Diesel Exhaust Particulate Matter in a Murine Asthma Model

Background and Objectives: Diesel exhaust particulate matter (DEPM) is an air pollutant that is associated with asthma. In this study, the therapeutic efficacy of Weissella cibaria strains CMU (Chonnam Medical University) and CMS (Chonnam Medical School) 1, together with the drug Synatura, an anti-tussive expectorant, was investigated in a murine asthma model exacerbated by DEPM. Materials and Methods: BALB/c mice were sensitized with ovalbumin (OVA) before intranasal challenge with OVA and DEPM. W. cibaria CMU, CMS1, and Synatura were administered orally for 21 days. Results: Neither Synatura nor W. cibaria strains affected spleen, liver, or lung weights. W. cibaria strains CMU and CMS1 significantly reduced the levels of interleukin (IL)-4, OVA-specific immunoglobulin E (IgE), and total lung collagen in bronchoalveolar lavage fluid (BALF), similar to those with Synatura, regardless of the oral dose concentration (p < 0.05). In addition, the W. cibaria CMU strain significantly alleviated IL-1β, IL-6, IL-12, monocyte chemotactic protein-1, and tumor necrosis factor-α in BALF, whereas the CMS1 strain significantly alleviated IL-10 and IL-12 in BALF (p < 0.05); however, Synatura did not show any statistical efficacy against them (p > 0.05). All concentrations of W. cibaria CMU and low concentrations of W. cibaria CMS1 significantly reduced lung bronchiolar changes and inflammatory cell infiltration. Conclusions: In conclusion, W. cibaria CMU in asthmatic mice showed better efficacy than W. cibaria CMS1 in improving asthma exacerbated by DEPM exposure, as well as better results than pharmaceuticals.

Inhalation bioaccessibility of multi-class organic pollutants associated to atmospheric PM2.5: Correlation with PM2.5 properties and health risk assessment

Inhalation exposure to fine particulate matter (PM_2.5) represents a global concern due to the adverse effects in human health. In the last years, scientific community has been adopted the assessment of the PM_2.5-bound pollutant fraction that could be released (bioaccessible fraction) in simulated lung fluids (SLFs) to achieve a better understanding of PM risk assessment and toxicological studies. Thus, bioaccessibility of 49 organic pollutants, including 18 polycyclic aromatic hydrocarbons (PAHs), 12 phthalate esters (PAEs), 11 organophosphorus flame retardants (OPFRs), 6 synthetic musk compounds (SMCs) and 2 bisphenols in PM_2.5 samples was evaluated. The proposed method consists of a physiologically based extraction test (PBET) by using artificial lysosomal fluid (ALF) to obtain bioaccessible fractions, followed by a vortex-assisted liquid-liquid microextraction (VALLME) and a final analysis by programmed temperature vaporization-gas chromatography-tandem mass spectrometry (PTV-GC-MS/MS). The highest inhalation bioaccessibility ratio was found for bisphenol A (BPA) with an average of 83%, followed by OPFRs, PAEs and PAHs (with average bioaccessibilities of 68%, 41% and 34%, respectively). Correlations between PM_2.5 composition (major ions, trace metals, equivalent black carbon (eBC) and UV-absorbing particulate matter (UVPM)) and bioaccessibility ratios were also assessed. Principal Component Analysis (PCA) suggested that PAHs, PAES and OPFRs bioaccessibility ratios could be positively correlated with PM_2.5 carbonaceous content. Furthermore, both inverse and positive correlations on PAHs, PAEs and OPFRs bioaccessibilites could be accounted for some major ions and metal (oid)s associated to PM_2.5, whereas no correlations comprising considered PM_2.5 major ions and metal (oid)s contents and BPA bioaccessibility was observed. In addition, health risk assessment of target PM_2.5-associated PAHs via inhalation was assessed in the study area considering both total and bioaccessible concentrations, being averaged human health risks within the safe carcinogenic and non-carcinogenic levels.

Environmental Pollutants and Oxidative Stress in Terrestrial and Aquatic Organisms: Examination of the Total Picture and Implications for Human Health

There is current great international concern about the contribution of environmental pollution to the global burden of disease particularly in the developing, low- and medium-income countries. Industrial activities, urbanization, developmental projects as well as various increased anthropogenic activities involving the improper generation, management and disposal of pollutants have rendered today’s environment highly polluted with various pollutants. These pollutants include toxic metals (lead, cadmium, mercury, arsenic), polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pesticides and diesel exhaust particles most of which appear to be ubiquitous as well as have long-term environmental persistence with a wide range of toxicities such as oxidative stress among others. Oxidative stress, which may arise from increased production of damaging free radicals emanating from increased pollutant burden and depressed bioavailability of antioxidant defenses causes altered biochemical and physiological mechanisms and has been implicated in all known human pathologies most of which are chronic. Oxidative stress also affects both flora and fauna and plants are very important components of the terrestrial environment and significant contributors of nutrients for both man and animals. It is also remarkable that the aquatic environment in which sea animals and creatures are resident is also highly polluted, leading to aquatic stress that may affect the survival of the aquatic animals, sharing in the oxidative stress. These altered terrestrial and aquatic environments have an overarching effect on human health. Antioxidants neutralize the damaging free radicals thus, they play important protective roles in the onset, progression and severity of the unmitigated generation of pollutants that ultimately manifest as oxidative stress. Consequently, human health as well as that of aquatic and terrestrial organisms may be protected from environmental pollution by mitigating oxidative stress and employing the principles of nutritional medicine, essentially based on antioxidants derived mainly from plants, which serve as the panacea of the vicious state of environmental pollutants consequently, the health of the population. Understanding the total picture of oxidative stress and integrating the terrestrial and aquatic effects of environmental pollutants are central to sustainable health of the population and appear to require multi-sectoral collaborations from diverse disciplinary perspectives; basically the environmental, agricultural and health sectors.

Potential Common Mechanisms of Cytotoxicity Induced by Amide Herbicides via TRPA1 Channel Activation

The “Multi-Threat Medical Countermeasure (MTMC)” strategy was proposed to develop a single drug with therapeutic efficacy against multiple pathologies or broad-spectrum protection against various toxins with common biochemical signals, molecular mediators, or cellular processes. This study demonstrated that cytotoxicity, expression of transient receptor potential cation channel subfamily A member 1 (TRPA1) mRNA, and intracellular calcium influx were increased in A549 cells exposed to amide herbicides (AHs), in which the order of cytotoxicity was metolachlor > acetochlor > propisochlor > alachlor > butachlor > propanil > pretilachlor, based on IC50 values of 430, 524, 564, 565, 619, 831, and 2333 μM, respectively. Inhibition/knockout of TRPA1 efficiently protected against cytotoxicity, decreased TRPA1 mRNA expression, and reduced calcium influx. The results suggested that the TRPA1 channel could be a key common target for AHs poisoning. The order of TRPA1 affinity for AHs was propanil > pretilachlor > metolachlor > (propiso/ala/aceto/butachlor), based on KD values of 16.2, 309, and 364 μM, respectively. The common molecular mechanisms of TRPA1-AHs interactions were clarified, including toxicity-effector groups (benzene ring, nitrogen/oxygen-containing functional groups, halogen) and residues involved in interactions (Lys787, Leu982). This work provides valuable information for the development of TRPA1 as a promising therapeutic target for broad-spectrum antitoxins.

Toxicological effects of traffic-related air pollution on the lungs: Evidence, biomarkers and intervention

BACKGROUND

Numerous epidemiological studies have recently observed that exposure to traffic-related air pollution (TRAP) is associated with increased risk of various respiratory diseases. Major gaps in knowledge remain regarding the toxicological effects.

OBJECTIVES

We examined the toxicological effects of the gasoline exhaust particles (GEP), a paradigm of TRAP, in rats, with an objective to provide the evidence, obtain the biomarkers, and suggest effective intervention measure.

METHODS

We measured the airway hyperresponsiveness (AHR), inflammatory cells in the bronchoalveolar lavage (BAL) fluid, histological changes in the lung tissues, and the biomarkers so as to systematically examine the toxicological effects of GEPs at different dose levels (0.5, 2.5, 5 mg/kg BW). The intervention of vitamin E (VE), a natural antioxidant, on the toxicological effects was investigated.

RESULTS

The lung injury caused by GEP exposure was first indicated by the airway hyperresponsiveness (AHR). Compared with the control group, GEP exposure significantly increased the airway resistances and decreased the lung compliance; the higher the dose of GEP, the more serious the lung injury. Lung injury was also revealed by the increase of inflammatory cells, including the lymphocytes and neutrophils, in the BAL fluid. With the increase of GEP dose, histological changes in the lung tissues were further observed: inflammatory cell infiltration increased and alveolar wall thickened. The toxicology of GEP was demonstrated by the increase of the biomarkers of the oxidative stress, the pro-inflammatory cytokines and the apoptosis cytokine. However, administration of VE was found to be effective in restoring airway injury.

CONCLUSION

The toxicological effects of traffic-related air pollution (TRAP) on rat lungs are supported by evidence and biomarkers, and vitamin E intervention is feasible.

A Review of Road Traffic-Derived Non-Exhaust Particles: Emissions, Physicochemical Characteristics, Health Risks, and Mitigation Measures

Implementation of regulatory standards has reduced exhaust emissions of particulate matter from road traffic substantially in the developed world. However, nonexhaust particle emissions arising from the wear of brakes, tires, and the road surface, together with the resuspension of road dust, are unregulated and exceed exhaust emissions in many jurisdictions. While knowledge of the sources of nonexhaust particles is fairly good, source-specific measurements of airborne concentrations are few, and studies of the toxicology and epidemiology do not give a clear picture of the health risk posed. This paper reviews the current state of knowledge, with a strong focus on health-related research, highlighting areas where further research is an essential prerequisite for developing focused policy responses to nonexhaust particles.

Urinary Eicosanoid Levels Reflect Allergen and Diesel Exhaust Coexposure and Are Linked to Impaired Lung Function

Eicosanoids are potent regulators of homeostasis and inflammation. Co-exposure to allergen and diesel exhaust (DE) have been shown to lead to eosinophilic inflammation, impaired airflow, and increased airway responsiveness. It is not clear whether eicosanoids mediate the mechanism by which these exposures impair lung function. We conducted a randomized, double-blinded, and four-arm crossover study. Fourteen allergen-sensitized participants were exposed to four conditions: negative control; allergen-alone exposure; DE and allergen coexposure; coexposure with particle-reducing technology applied. Quantitative metabolic profiling of urinary eicosanoids was performed using LC-MS/MS. As expected, allergen inhalation increased eicosanoids. The prostacyclin metabolite 2,3-dinor-6-keto-PGF_1α (PGF_1α, prostaglandin F_1α) increased with coexposure, but particle depletion suppressed this pathway. Individuals with a high genetic risk score demonstrated a greater increase in isoprostane metabolites following coexposure. Causal mediation analyses showed that allergen induced airflow impairment was mediated via leukotriene E₄ and tetranor-prostaglandin D metabolite. Overall, DE exposure did not augment the allergen's effect on urinary eicosanoids, except insofar as variant genotypes conferred susceptibility to the addition of DE in terms of isoprostane metabolites. These findings will add to the body of previous controlled human exposure studies and provide greater insight into how complex environmental exposures in urban air may influence individuals with sensitivity to aeroallergens.

Prevalence, time trends and treatment practices of asthma in India: the Global Asthma Network study

Objective

The objective of this subanalysis of data from centres across urban areas in India of the Global Asthma Network (GAN) was to study 1) the prevalence of symptoms of asthma in children and adults, 2) the change in prevalence of asthma and its trigger factors since the International Study of Asthma and Allergies in Childhood (ISAAC), and 3) current asthma treatment practice.

Methods

In this cross-sectional, multicentre, school-based and self-administered questionnaire, responses from children aged 6-7 years and 13-14 years, and their respective parents, were analysed.

Results

The GAN Phase I study included 20 084 children in the 6-7-year age group, 25 887 children in the 13-14-year age group and 81 296 parents. The prevalence of wheeze in the previous 12 months was 3.16%, 3.63% and 3.30% in the three groups, respectively. In comparison to the ISAAC studies, there was a significant reduction in the prevalence of current wheeze (p<0.001). Bivariate analysis revealed a significant reduction in the prevalence of trigger factors. Almost 82% of current wheezers and 70% of subjects with symptoms of severe asthma were not clinically diagnosed as having asthma. The daily use of inhaled corticosteroids (ICS) was less than 2.5% in subjects with current wheeze and those with symptoms of severe asthma but less than 1% used daily ICS when asthma remained undiagnosed.

Conclusion

The prevalence of current wheeze and its causal factors showed a significant reduction compared to previous ISAAC studies. Among subjects with current wheeze and symptoms of severe asthma, the problem of under-diagnosis and under-treatment was widespread.

Time-Specific Factors Influencing the Development of Asthma in Children

Susceptibility to asthma is complex and heterogeneous, as it involves both genetic and environmental insults (pre- and post-birth) acting in a critical window of development in early life. According to the Developmental Origins of Health and Disease, several factors, both harmful and protective, such as nutrition, diseases, drugs, microbiome, and stressors, interact with genotypic variation to change the capacity of the organism to successfully adapt and grow in later life. In this review, we aim to provide the latest evidence about predictive risk and protective factors for developing asthma in different stages of life, from the fetal period to adolescence, in order to develop strategic preventive and therapeutic interventions to predict and improve health later in life. Our study shows that for some risk factors, such as exposure to cigarette smoke, environmental pollutants, and family history of asthma, the evidence in favor of a strong association of those factors with the development of asthma is solid and widely shared. Similarly, the clear benefits of some protective factors were shown, providing new insights into primary prevention. On the contrary, further longitudinal studies are required, as some points in the literature remain controversial and a source of debate.

Associations of Exposure to Nitrogen Oxides with Prevalent Asthma and Other Atopic Diseases in Israel

Childhood exposure to nitrogen oxides (NOx) is considered a risk factor for the onset of asthma. However, associations of this exposure with other atopic diseases and factors that modify this association are less clear. We aimed to study associations between exposure to NOx and the prevalence of atopic diseases in Israeli adolescents using a cross-sectional design. The study population comprised all Israeli-born adolescents whose medical status was evaluated for mandatory military recruitment during 1967–2017 (n = 2,523,745), of whom 5.9% had prevalent asthma. We based the exposure assessments on a land-use regression model and estimated associations using multivariable logistic regression models. Across all periods, mean exposure to NOx from birth to adolescence was associated with prevalent asthma at the examination in a dose-response manner, with an odds ratio for the upper quintile of 1.61 (95% CI: 1.56–1.67), in comparison to the lowest quintile. Associations were stronger in males and in lower socioeconomic strata. We found the strongest associations for asthma with comorbid rhinitis, with an almost twofold increase in the odds of upper versus lower quintile of exposure (odds ratio = 1.96, 95% CI: 1.82–2.11). Rhino-conjunctivitis and allergic atopic dermatitis suggested a possible threshold level with NOx. Capsule Summary: Research indicates that half of the global population will suffer from an allergic condition at some point in life. Childhood exposure to nitrogen oxides is a risk factor for the onset of asthma. The association between exposure and allergic diseases other than asthma is unclear. We demonstrate a strong, dose-response relationship between exposure and a group of allergic outcomes, using data comprising 2.5 million subjects over 50 years. The large health benefits from clean air should motivate governments to prioritize mitigation measures.

Molecular mechanisms of oxidative stress in asthma

The lungs are exposed to reactive oxygen species oxygen (ROS) produced as a result of inhalation of oxygen, as well as smoke and other air pollutants. Cell metabolism and the NADPH oxidases (Nox) generate low levels of intracellular ROS that act as signal transduction mediators by inducing oxidative modifications of histones, enzymes and transcription factors. Redox signalling is also regulated by localised production and sensing of ROS in mitochondria, the endoplasmic reticulum (ER) and inside the nucleus. Intracellular ROS are maintained at low levels through the action of a battery of enzymatic and non-enzymatic antioxidants. Asthma is a heterogeneous airway inflammatory disease with different immune endotypes; these include atopic or non-atopic Th2 type immune response associated with eosinophilia, or a non-Th2 response associated with neutrophilia. Airway remodelling and hyperresponsiveness accompany the inflammatory response in asthma. Over-production of ROS resulting from infiltrating immune cells, particularly eosinophils and neutrophils, and a concomitant impairment of antioxidant responses lead to development of oxidative stress in asthma. Oxidative stress is augmented in severe asthma and during exacerbations, as well as by air pollution and obesity, and causes oxidative damage of tissues promoting airway inflammation and hyperresponsiveness. Furthermore, deregulated Nox activity, mitochondrial dysfunction, ER stress and/or oxidative DNA damage, resulting from exposure to irritants, inflammatory mediators or obesity, may lead to redox-dependent changes in cell signalling. ROS play a central role in airway epithelium-mediated sensing, development of innate and adaptive immune responses, and airway remodelling and hyperresponsiveness. Nonetheless, antioxidant compounds have proven clinically ineffective as therapeutic agents for asthma, partly due to issues with stability and in vivo metabolism of these compounds. The compartmentalised nature of ROS production and sensing, and the role of ROS in homeostatic responses and in the action of corticosteroids and β2-adrenergic receptor agonists, adds another layer of complexity to antioxidant therapy development. Nox inhibitors and mitochondrial-targeted antioxidants are in clinical development for a number of diseases but they have not yet been investigated in asthma. A better understanding of the complex role of ROS in the pathogenesis of asthma will highlight new opportunities for more targeted and effective redox therapies.

The aggravation of allergic airway inflammation with dibutyl phthalate involved in Nrf2-mediated activation of the mast cells

Dibutyl phthalate (DBP)-an organic pollutant-is ubiquitous in the environment. DBP as an immune adjuvant is related to the development of multiple allergic diseases. However, the current research involving DBP-induced pulmonary toxicity remains poorly understood. Therefore, this research aimed to explore the adverse effect and potential mechanism of DBP exposure on the lungs in rats. In our study, ovalbumin was used to build a rat model of allergic airway inflammation to study any harmful effect of DBP exposure on lung tissues. Rats were treated by intragastric administration of DBP (500 mg kg^-1 or 750 mg kg^-1) and/or subcutaneous injection of SFN (4 mg kg^-1). The results of histopathological analysis, cell count, and myeloperoxidase showed that DBP promoted the inflammatory damage of lungs. In the lung tissues, the detection of terminal deoxynucleotidyl transferase dUNT nick end labeling and oxidative stress indices showed that DBP significantly increased the level of apoptosis and oxidative stress. Western blot analysis indicated that DBP raised the expression level of thymic stromal lymphopoietin and reduced the nuclear expression level of nuclear factor-erythroid-2-related factor 2 (Nrf2), which was further verified by quantitative real-time PCR. Meanwhile, DBP treatment markedly up-regulated the inflammatory cytokines such as IL-4 and IL-13, and rat mast cell protease-2, a marker secreted by mast cells (MCs). Conversely, sulforaphane, a Nrf2 inducer, ameliorated the pulmonary damage induced by DBP in the above. Altogether, our data provides a new insight into the impacts of the activation of MCs on the DBP-induced pulmonary toxicity as well as the safety evaluation of DBP.

Air Pollution Relates to Airway Pathology in Wheezing Children

Rationale: Outdoor air pollution contributes to asthma development and exacerbations, yet its effects on airway pathology have not been defined in children.

Objectives: To explore the possible link between air pollution and airway pathology, we retrospectively examined the relationship between environmental pollutants and pathological changes in bronchial biopsy specimens from children undergoing a clinically indicated bronchoscopy.

Methods: Structural and inflammatory changes (basement membrane [BM] thickness, epithelial loss, eosinophils, neutrophils, macrophages, mast cells, and lymphocytes) were quantified in biopsy specimens by using immunohistochemistry. The association between exposure to particulate matter less than 10 μm in aerodynamic diameter (PM₁₀), SO₂ and NO₂ and biopsy findings was evaluated by using a generalized additive model with Gamma family to allow for overdispersion, adjusted for atmospheric pressure, temperature, humidity, and wheezing.

Results: Overall, 98 children were included (age 5.3 ± 2.9 yr; 53 with wheezing/45 without wheezing). BM thickness increased with prolonged exposure to PM₁₀ (rate ratio [RR], 1.29; 95% confidence interval [CI], 1.09–1.52), particularly in children with wheezing. Prolonged exposure to PM₁₀ was also associated with eosinophilic inflammation in children with wheezing (RR, 3.16; 95% CI, 1.35–7.39). Conversely, in children without wheezing, increased PM₁₀ exposure was associated with a reduction of eosinophilic inflammation (RR, 0.12; 95% CI, 0.02–0.6) and neutrophilic inflammation (RR, 0.36; 95% CI, 0.14–0.89). Moreover, NO₂ exposure was also linked to reductions in neutrophil infiltration (RR, 0.57; 95% CI, 0.34–0.93) and eosinophil infiltration (RR, 0.33; 95% CI, 0.14–0.77).

Conclusions: Different patterns of association were observed in children with wheezing and in children without wheezing. In children without wheezing, exposure to PM₁₀ and NO₂ was linked to reduced eosinophilic and neutrophilic inflammation. Conversely, in children with wheezing, prolonged exposure to PM₁₀ was associated with increased BM thickness and eosinophilic inflammation, suggesting that it might contribute to asthma development by promoting airway remodeling and inflammation.

Role of diesel exhaust particles in the induction of allergic asthma to low doses of soybean

INTRODUCTION

Exposure to environmental pollutants such as diesel exhaust particles (DEP) increases the risk of asthma and asthma exacerbation. However, the exact mechanisms inducing asthma to low doses of allergens remain poorly understood. The present study aimed to analyse the immunomodulatory effect of the inhalation of DEP in a mouse model exposed to non-asthmagenic doses of soybean hull extract (SHE).

MATERIAL AND METHODS

BALB/c ByJ mice were randomly divided into four experimental groups. Two groups received nasal instillations of saline and the other two groups received 3 mg ml-1 SHE during 5 days per week for 3 weeks. One group in each pair also received 150 μg of DEP in the same instillations 3 days per week. SHE-specific IgE levels, oxidative stress, leukocyte pattern and optical projection tomography (OPT) imaging studies were assessed.

RESULTS

Inhalation of SHE and/or DEP increased levels of H2O2 in BAL, while coexposure to SHE and DEP increased SHE-specific IgE levels in serum. Inhalation of SHE alone increased eosinophils, B cells, total and resident monocytes and decreased levels of NK cells, while inhalation of DEP increased neutrophils and decreased total monocytes. Regarding dendritic cells (DC), the inhalation of SHE and/or DEP increased the total population, while the inhalation of SHE alone increased Th2-related DCs (CD11b + Ly6C-) and decreased tolerogenic DCs (CD11b-Ly6C-). However, coexposure to SHE and DEP increased oxidative stress-sensitive DCs (CD11b-Ly6C+) and decreased Th1-related DCs (CD11b + Ly6C+). As regards macrophages, inhalation of SHE and DEP decreased total and alveolar populations. DEP deposition in lung tissue did not differ between groups.

CONCLUSION

Coexposure to DEP activates the asthmatic response to low doses of soy by triggering the immune response and oxidative stress.

Polluted Air Exposure Compromises Corneal Immunity and Exacerbates Inflammation in Acute Herpes Simplex Keratitis

Air pollution is a serious environmental issue worldwide in developing countries’ megacities, affecting the population’s health, including the ocular surface, by predisposing or exacerbating other ocular diseases. Herpes simplex keratitis (HSK) is caused by the herpes simplex virus type 1 (HSV-1). The primary or recurring infection in the ocular site causes progressive corneal scarring that may result in visual impairment. The present study was designed to study the immunopathological changes of acute HSK under urban polluted air, using the acute HSK model combined with an experimental urban polluted air exposure from Buenos Aires City. We evaluated the corneal clinical outcomes, viral DNA and pro-inflammatory cytokines by RT-PCR and ELISA assays, respectively. Then, we determined the innate and adaptive immune responses in both cornea and local lymph nodes after HSV-1 corneal by immunofluorescence staining and flow cytometry. Our results showed that mice exposed to polluted air develop a severe form of HSK with increased corneal opacity, neovascularization, HSV-1 DNA and production of TNF-α, IL-1β, IFN-γ, and CCL2. A high number of corneal resident immune cells, including activated dendritic cells, was observed in mice exposed to polluted air; with a further significant influx of bone marrow-derived cells including GR1+ cells (neutrophils and inflammatory monocytes), CD11c+ cells (dendritic cells), and CD3+ (T cells) during acute corneal HSK. Moreover, mice exposed to polluted air showed a predominant Th1 type T cell response over Tregs in local lymph nodes during acute HSK with decreased corneal Tregs. These findings provide strong evidence that urban polluted air might trigger a local imbalance of innate and adaptive immune responses that exacerbate HSK severity. Taking this study into account, urban air pollution should be considered a key factor in developing ocular inflammatory diseases.

Combined Toxicity of Metal Nanoparticles: Comparison of Individual and Mixture Particles Effect

Toxicity of metal nanoparticles (NPs) are closely associated with increasing intracellular reactive oxygen species (ROS) and the levels of pro-inflammatory mediators. However, NP interactions and surface complexation reactions alter the original toxicity of individual NPs. To date, toxicity studies on NPs have mostly been focused on individual NPs instead of the combination of several species. It is expected that the amount of industrial and highway-acquired NPs released into the environment will further increase in the near future. This raises the possibility that various types of NPs could be found in the same medium, thereby, the adverse effects of each NP either could be potentiated, inhibited or remain unaffected by the presence of the other NPs. After uptake of NPs into the human body from various routes, protein kinases pathways mediate their toxicities. In this context, family of mitogen-activated protein kinases (MAPKs) is mostly efficient. Despite each NP activates almost the same metabolic pathways, the toxicity induced by a single type of NP is different than the case of co-exposure to the combined NPs. The scantiness of toxicological data on NPs combinations displays difficulties to determine, if there is any risk associated with exposure to combined nanomaterials. Currently, in addition to mathematical analysis (Response surface methodology; RSM), the quantitative-structure-activity relationship (QSAR) is used to estimate the toxicity of various metal oxide NPs based on their physicochemical properties and levels applied. In this chapter, it is discussed whether the coexistence of multiple metal NPs alter the original toxicity of individual NP. Additionally, in the part of "Toxicity of diesel emission/exhaust particles (DEP)", the known individual toxicity of metal NPs within the DEP is compared with the data regarding toxicity of total DEP mixture.

Inhalation bioaccessibility estimation of polycyclic aromatic hydrocarbons from atmospheric particulate matter (PM10): Influence of PM10 composition and health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) inhalation bioaccessibility was assessed in 65 atmospheric particulate matter samples (PM₁₀) collected at an Atlantic coastal European urban site. The proposed method consists on a physiologically based extraction (PBET) by using Gamble's solution followed by a vortex assisted liquid-liquid micro-extraction (VALLME) and quantification by high performance liquid chromatography with fluorescence detection (HPLC-FLD). The use of a micro-extraction technique combined with FLD detection, provides a simple, fast, sensitive, accurate and low-cost methodology to PAHs quantification in bioaccessible fractions. Accuracy of the bioaccessibility study was assessed by means of a mass balance approaches using a PM₁₀ filter and a certified reference material (ERM-CZ100). High-moderate inhalation bioaccessibilities were found for phenanthrene (Phe), fluoranthene (Ft) and pyrene (Pyr) (average ratios in the 52-65% range); while dibenz (a,h)anthracene (DBahA), indeno (1,2,3-cd)pyrene (IP) and benzo (g,h,i)perylene (BghiP) were observed to be less bioaccessibles (average ratios in the 11-14% range). Relationship between PM₁₀ composition (major ions, trace metals, equivalent black carbon (eBC) and UV-absorbing particulate matter (UVPM)) and PAHs bioaccessibility ratios was also assessed. Principal Component Analysis (PCA) showed that PAHs bioaccessibility percentage is dependent on anthropogenic (eBC, UVPM and Sb concentrations) and marine sources of PM₁₀. Predicted PAHs bioaccessibilities after applying a multiple linear regression model based on marine and anthropogenic source of PM₁₀ could also be established. Health risk assessment of target PM₁₀-associated PAHs via inhalation was assessed considering bioaccessibility concentrations by using hazard index (HI) and BaP equivalent concentration (BaP_eq) approaches, suggesting no carcinogenic risk in the area during the sampling campaign.

Allergic rhinitis

Allergic rhinitis (AR) is caused by immunoglobulin E (IgE)-mediated reactions to inhaled allergens and is one of the most common chronic conditions globally. AR often co-occurs with asthma and conjunctivitis and is a global health problem causing major burden and disability worldwide. Risk factors include inhalant and occupational allergens, as well as genetic factors. AR impairs quality of life, affects social life, school and work, and is associated with substantial economic costs. The Allergic Rhinitis and its Impact on Asthma (ARIA) initiative classified AR into intermittent or persistent and mild or moderate/severe. The diagnosis is based on the clinical history and, if needed in patients with uncontrolled rhinitis despite medications or with long-lasting symptoms, on skin tests or the presence of serum-specific IgE antibodies to allergens. The most frequently used pharmacological treatments include oral, intranasal or ocular H₁-antihistamines, intranasal corticosteroids or a fixed combination of intranasal H₁-antihistamines and corticosteroids. Allergen immunotherapy prescribed by a specialist using high-quality extracts in stratified patients is effective in patients with persistent symptoms. Real-world data obtained by mobile technology offer new insights into AR phenotypes and management. The outlook for AR includes a better understanding of novel multimorbid phenotypes, health technology assessment and patient-centred shared decision-making.

Advances and novel developments in environmental influences on the development of atopic diseases

Although genetic factors play a role in the etiology of atopic disease, the rapid increases in the prevalence of these diseases over the last few decades suggest that environmental, rather than genetic factors are the driving force behind the increasing prevalence. In modern societies, there is increased time spent indoors, use of antibiotics, and consumption of processed foods and decreased contact with farm animals and pets, which limit exposure to environmental allergens, infectious parasitic worms, and microbes. The lack of exposure to these factors is thought to prevent proper education and training of the immune system. Increased industrialization and urbanization have brought about increases in organic and inorganic pollutants. In addition, Caesarian birth, birth order, increased use of soaps and detergents, tobacco smoke exposure and psychosomatic factors are other factors that have been associated with increased rate of allergic diseases. Here, we review current knowledge on the environmental factors that have been shown to affect the development of allergic diseases and the recent developments in the field.

Lactic Acid Bacteria Ameliorate Diesel Exhaust Particulate Matter-Exacerbated Allergic Inflammation in a Murine Model of Asthma

Several air pollution components such as sulfur dioxide, ozone, nitrogen dioxide, and diesel exhaust particulate matter (DEPM) have been linked to the development of asthma. In this study, we investigated the therapeutic potential of three lactic acid bacteria species, Lactobacillus plantarum GREEN CROSS Wellbeing (GCWB)1001, Pediococcus acidilactici GCWB1085, and Lactobacillus rhamnosus GCWB1156, in preventing DEPM-exacerbated asthma in mice. BALB/c mice were first sensitized with ovalbumin (OVA) and were either challenged with OVA or DEPM (DEPM-exacerbated asthma model) by intranasal instillation. All three strains showed no hemolytic activity, suggesting a good safety profile. Oral administration of lactic acid bacteria reduced OVA + DEPM-induced inflammatory infiltration, goblet cell hyperplasia, airway remodeling, and the levels of proinflammatory cytokines and chemokines in bronchoalveolar lavage fluid (BALF). The probiotics also attenuated OVA + DEPM-induced immunoglobulin E (IgE) levels in serum and in BALF, and significantly reduced caspase-3 activity, total collagen level, and matrix metalloproteinase (MMP)-9 activity. In conclusion, lactic acid bacteria such as L. plantarum GCWB1001, P. acidilactici GCWB1085, and L. rhamnosus treatment in mice with asthma showed significant efficacy in preventing lung inflammation exacerbated by DEPM administration.

The Challenge by Multiple Environmental and Biological Factors Induce Inflammation in Aging: Their Role in the Promotion of Chronic Disease

The aging process is driven by multiple mechanisms that lead to changes in energy production, oxidative stress, homeostatic dysregulation and eventually to loss of functionality and increased disease susceptibility. Most aged individuals develop chronic low-grade inflammation, which is an important risk factor for morbidity, physical and cognitive impairment, frailty, and death. At any age, chronic inflammatory diseases are major causes of morbimortality, affecting up to 5-8% of the population of industrialized countries. Several environmental factors can play an important role for modifying the inflammatory state. Genetics accounts for only a small fraction of chronic-inflammatory diseases, whereas environmental factors appear to participate, either with a causative or a promotional role in 50% to 75% of patients. Several of those changes depend on epigenetic changes that will further modify the individual response to additional stimuli. The interaction between inflammation and the environment offers important insights on aging and health. These conditions, often depending on the individual's sex, appear to lead to decreased longevity and physical and cognitive decline. In addition to biological factors, the environment is also involved in the generation of psychological and social context leading to stress. Poor psychological environments and other sources of stress also result in increased inflammation. However, the mechanisms underlying the role of environmental and psychosocial factors and nutrition on the regulation of inflammation, and how the response elicited for those factors interact among them, are poorly understood. Whereas certain deleterious environmental factors result in the generation of oxidative stress driven by an increased production of reactive oxygen and nitrogen species, endoplasmic reticulum stress, and inflammation, other factors, including nutrition (polyunsaturated fatty acids) and behavioral factors (exercise) confer protection against inflammation, oxidative and endoplasmic reticulum stress, and thus ameliorate their deleterious effect. Here, we discuss processes and mechanisms of inflammation associated with environmental factors and behavior, their links to sex and gender, and their overall impact on aging.

The immunomodulatory effects of diesel exhaust particles in asthma

Ammonium persulfate (AP) causes occupational asthma (OA) and diesel exhaust particles (DEP) exacerbate asthma; however, the role of DEP in asthma due to chemical agents has not been assessed to date. Therefore, the present work aims to study the immunomodulatory effects of DEP in a mouse model of chemical asthma. BALB/c ByJ mice were randomly divided into four experimental groups. On days 1 and 8, mice were dermally sensitized with AP or saline. On days 15, 18 and 21, they received intranasal instillations of AP or saline. Two experimental groups received DEP on every of the three challenges. Airway hyperresponsiveness (AHR), lung mechanics, pulmonary inflammation in bronchoalveolar lavage, leukocyte numbers in total lung tissue, oxidative stress and optical projection tomography (OPT) studies were assessed. The AP-sensitized and challenged group showed asthma-like responses, such as airway hyperresponsiveness, increased levels of eosinophils and NKs and lower numbers of monocytes and CD11b-Ly6C- dendritic cells (DCs). Mice exposed to DEP alone showed increased levels of neutrophils and NKs, reduced numbers of monocytes and alveolar macrophages, and increased levels of CD11b + Ly6C- DCs. The AP sensitized and AP + DEP challenged group also showed asthma-like symptoms such as AHR, as well as increased numbers of eosinophils, neutrophils, CD11b + Ly6C- DCs and decreased levels of total and alveolar macrophages and tolerogenic DCs. Particle deposition was visualised using OPT. In the DEP group the particles were distributed relatively evenly, while in the AP + DEP group they were seen mainly in the large conducting airways. The results show that DEP exposure activates the innate immune response and, together with AP, exacerbates asthma immune hallmarks. This mouse model provides the first evidence of the capacity of DEPs to increase CD11b + Ly6C- (Th2-related) DCs. This study also demonstrates, for the first time, a differential deposition pattern of DEP in lungs depending on asthma status.

A Multifactorial Evaluation of the Effects of Air Pollution and Meteorological Factors on Asthma Exacerbation

In the real world, dynamic changes in air pollutants and meteorological factors coexist simultaneously. Studies identifying the effects of individual pollutants on acute exacerbation (AE) of asthma may overlook the health effects of the overall combination. A comprehensive study examining the influence of air pollution and meteorological factors is required. Asthma AE data from emergency room visits were collected from the Taiwan National Health Insurance Research Database. Complete monitoring data for air pollutants (SO₂; NO₂; O₃; CO; PM_2.5; PM₁₀) and meteorological factors were collected from the Environmental Protection Agency monitoring stations. A bi-directional case-crossover analysis was used to investigate the effects of air pollution and meteorological factors on asthma AE. Among age group divisions, a 1 °C temperature increase was a protective factor for asthma ER visits with OR = 0.981 (95% CI, 0.971–0.991) and 0.985 (95% CI, 0.975–0.994) for pediatric and adult patients, respectively. Children, especially younger females, are more susceptible to asthma AE due to the effects of outdoor air pollution than adults. Meteorological factors are important modulators for asthma AE in both asthmatic children and adults. When studying the effects of air pollution on asthma AE, meteorological factors should be considered.

Outdoor Air Pollution and New-Onset Airway Disease. An Official American Thoracic Society Workshop Report

Although it is well accepted that air pollution exposure exacerbates preexisting airway disease, it has not been firmly established that long-term pollution exposure increases the risk of new-onset asthma or chronic obstruction pulmonary disease (COPD). This Workshop brought together experts on mechanistic, epidemiological, and clinical aspects of airway disease to review current knowledge regarding whether air pollution is a causal factor in the development of asthma and/or COPD. Speakers presented recent evidence in their respective areas of expertise related to air pollution and new airway disease incidence, followed by interactive discussions. A writing committee summarized their collective findings. The Epidemiology Group found that long-term exposure to air pollution, especially metrics of traffic-related air pollution such as nitrogen dioxide and black carbon, is associated with onset of childhood asthma. However, the evidence for a causal role in adult-onset asthma or COPD remains insufficient. The Mechanistic Group concluded that air pollution exposure can cause airway remodeling, which can lead to asthma or COPD, as well as asthma-like phenotypes that worsen with long-term exposure to air pollution, especially fine particulate matter and ozone. The Clinical Group concluded that air pollution is a plausible contributor to the onset of both asthma and COPD. Available evidence indicates that long-term exposure to air pollution is a cause of childhood asthma, but the evidence for a similar determination for adult asthma or COPD remains insufficient. Further research is needed to elucidate the exact biological mechanism underlying incident childhood asthma, and the specific air pollutant that causes it.

Omega 3 Supplementation Can Regulate Inflammatory States in Gas Station Workers: A Double-Blind Placebo-Controlled Clinical Trial

Environmental exposure to diesel particulate matter and commercial gasoline in gas station workers might induce oxidative stress and changes in the balance of the immune system. In this study, the immunomodulatory impacts of omega 3 fatty acid (ω3FA) supplement were assessed on inflammatory and anti-inflammatory markers in gas station workers in a double-blind placebo-controlled clinical trial. Fifty-three men working in gas stations were treated with ω3FA (n = 29) or placebo (n = 24) for 60 days. C-reactive protein, interleukin-12 (IL-12), transforming growth factor β (TGF-β), interferon γ (IFN-γ), tumor necrosis factor α, IL-10, and IL-17 levels were measured by enzyme-linked immunosorbent assay method before and after the completion of the trial. The concentrations of IFN-γ and IL-17 were significantly decreased in ω3FA group compared with the placebo group (P < 0.001). Moreover, the levels of inhibitory cytokines including TGF-β and IL-10 significantly were increased in ω3FA group (P < 0.001). Overall, ω3FA nutritional supplementation can be useful in reducing inflammatory immune responses and maintaining immune tolerance in people with high exposure to inflammation-inducing factors. [Figure: see text].

Maternal 1-nitropyrene exposure during pregnancy increases susceptibility of allergic asthma in adolescent offspring

1-nitropyrene (1-NP) is widespread in the environment, as a typical nitrated polycyclic aromatic hydrocarbon. The purpose of this research was to explore the effects of gestational 1-NP exposure on susceptibility of allergic asthma in offspring. Maternal mice were exposed to 1-NP (100 μg kg^-1) by gavage throughout the whole pregnancy. Pups were sensitized by injecting with ovalbumin (OVA) on postnatal day (PND)23, 29, and 36, respectively. At 7 days following the last injection, sensitized mice were exposed to aerosol OVA. As expected, there were quite a few inflammatory cells in the lungs of OVA-sensitized pups, accompanied by bronchial wall thickening and hyperemia. Elevated goblet cells and overproduced mucus were observed in the airways of OVA-sensitized pups. Interestingly, gestational 1-NP exposure aggravated infiltration of inflammatory cells, mainly eosinophils, in OVA-sensitized offspring. Although it had little effect on airway smooth muscle layer thickening and basement membrane fibrosis, gestational 1-NP exposure aggravated goblet cell hyperplasia, Muc5ac mRNA upregulation, and mucus secretion in the airways of OVA-sensitized and challenged offspring. Mechanistically, gestational 1-NP exposure aggravated elevation of pulmonary IL-5 in OVA-sensitized pups. These findings suggest that gestational 1-NP exposure increases susceptibility of allergic asthma in offspring.

The Role and Potential Pathogenic Mechanism of Particulate Matter in Childhood Asthma: A Review and Perspective

Asthma, the most common chronic respiratory disease in children, affects numerous people worldwide. Accumulating evidence suggests that exposure to high levels of particulate matter (PM), either acutely or chronically, is associated with the exacerbation and incidence of pediatric asthma. However, the detailed pathogenic mechanisms by which PM contributes to the incidence of asthma remain largely unknown. In this short review, we summarize studies of relationships between PM and pediatric asthma and recent advances on the fundamental mechanisms of PM-related asthma, with emphases on cell death regulation and immune system responses. We further discuss the inadequacy of current studies and give a perspective on the prevention strategies for pediatric asthma.

Obesity Does Not Increase the Risk of Asthma Readmissions

The relationship between obesity and asthma exacerbations is still under debate. The aim of our work is to analyse the relationship between obesity and hospital re-admissions in asthmatics. A review was retrospectively performed on all hospital admissions of adult patients due to asthma exacerbation occurring in our hospital for 11 years. All those cases with asthma as the first diagnosis in the discharge report were included, or those with asthma as the second diagnosis provided when the first diagnosis was respiratory infection or respiratory failure. Only the first hospital admission of each patient was included in this study. The Odds Ratios of a higher incidence of early/late readmissions due to asthma exacerbation were calculated using a binary logistic regression, using the body mass index (BMI) as independent variable, adjusted for all the variables included in the study. The study included 809 patients with a mean age of 55.6 years, and 65.2% were female. The majority (71.4%) were obese or overweight. No significant relationship was observed in the univariate or multivariate analyses between overweight or obesity and the early or late hospital readmissions due to asthma. Therefore, obesity does not seem to be a determining factor in the risk of asthma exacerbations.

All the small things: How virus-like particles and liposomes modulate allergic immune responses

Recent years have seen a dramatic increase in the range of applications of virus‐like nanoparticle (VNP)‐ and liposome‐based antigen delivery systems for the treatment of allergies. These platforms rely on a growing number of inert virus‐backbones or distinct lipid formulations and intend to engage the host's innate and/or adaptive immune system by virtue of their co‐delivered immunogens. Due to their particulate nature, VNP and liposomal preparations are also capable of breaking tolerance against endogenous cytokines, Igs, and their receptors, allowing for the facile induction of anti‐cytokine, anti‐IgE, or anti‐FcεR antibodies in the host. We here discuss the “pros and cons” of inducing such neutralizing autoantibodies. Moreover, we cover another major theme of the last years, i.e., the engineering of non‐anaphylactogenic particles and the elucidation of the parameters relevant for the specific trafficking and processing of such particles in vivo. Finally, we put the various technical advances in VNP‐ and liposome‐research into (pre‐)clinical context by referring and critically discussing the relevant studies performed to treat allergic diseases.

Air pollution exposures from multiple point sources and risk of incident chronic obstructive pulmonary disease (COPD) and asthma

BACKGROUND

Exposure to environmental air pollutants exacerbates respiratory illness, but prospective studies of disease incidence are uncommon. Further, attempts to estimate effects from multiple point sources have rarely been undertaken. The current study examined risk of incident chronic obstructive pulmonary disease (COPD) and asthma in association with emissions of multiple air pollutants from point pollution sources in Australia.

METHODS

We analyzed prospective cohort data from the Australian Longitudinal Study on Women's Health. Women from three age-cohorts (N = 35,755) were followed for up to 21 years for incident COPD and asthma. Exposures were measured from the National Pollutant Inventory and included carbon monoxide, nitrogen oxides, sulfur dioxide, and particulate matter (PM2.5 and PM10). We identified inverse-distance weighted emissions in kilograms that women experienced over time from point sources within 10 km of their residences. Cox proportional hazards regression models examined risk of self-reported doctor-diagnosed COPD and asthma in association with pollutant exposures and covariates.

RESULTS

New COPD cases numbered 3616 (11.5%) and new asthma cases numbered 2725 (9.4%). Participants were exposed to an average of 47-59 sites with air pollution emissions within 10 km of their residences. Fossil fuel electricity generation and mining made the largest contributions to air pollution but hundreds of other types of emissions also occurred. Controlling for covariates, all five air pollutants modeled individually were significantly associated with risk of COPD. Modeled jointly, only sulfur dioxide (SO₂) remained significantly associated with COPD (HR = 1.038, 95% CI = 1.010-1.067), although the five pollutants were highly correlated (r = 0.89). None of the pollutants were significantly associated with adult onset asthma. Cohort-specific analyses indicated that COPD risk was significantly associated with SO₂ exposure for younger (HR = 1.021, CI = 1.001-1.047), middle-age (HR = 1.019, CI = 1.004-1.034) and older cohorts (HR = 1.025, CI = 1.004-1.047).

CONCLUSIONS

Multiple exposure sources and pollutants contributed to COPD risk, including electricity generation and mining but extending to many industrial processes. The results highlight the importance of policy efforts and technological improvements to reduce harmful air pollution emissions across the industrial landscape.

Prevalence and impact of risk factors for poor asthma outcomes in a large, specialist-managed patient cohort: a real-life study

Background

Risk factors for poor asthma outcomes may have considerable influence on the control level and medical care of asthmatic patients. Our objective was to conduct a study that provides data on the level of symptom control and the frequency of specific risk factors for poor asthma outcomes on a large patient cohort.

Methods

A cross-sectional, non-interventional real-life study was conducted among asthmatic patients treated by respiratory specialists in Hungary. Asthma control and risk factor assessment were done according to Global Initiative for Asthma guideline (Box 2–2). In the data analysis, phase descriptive statistics, graphical outputs, and Fisher’s exact tests were used.

Results

Of 12743 patients enrolled by 187 specialists, asthma was well controlled in 36.0%, partially controlled in 29.29%, and uncontrolled in 34.71% of the cases. The most common comorbidities were rhinitis/sinusitis (66.84%), cardiovascular diseases (43.81%), and gastroesophageal reflux disease (20.11%). The following risk factors had the strongest relationship with uncontrolled disease: incorrect inhaler technique causing side effects (odds ratio, OR 4.86, 3.51–6.8), previous severe exacerbation (OR 4.79, 4.02–5.72), high short-acting beta agonist (SABA) use (OR 4.46, 4.03–4.93), incorrect inhaler technique associated with an exacerbation (OR 3.91, 3.06–5.03), and persistently low forced expiratory volume in 1 s (FEV₁, OR 3.14, 2.8–3.52). The most frequent risk factors were smoking (OR 1.47, 1.36–1.59) and obesity (OR 1.34, 1.24–1.45). Furthermore, high loss of control was associated with an initial low FEV₁ (OR 2.21, 2.01–2.44), frequent oral corticosteroid (OCS) use (OR 1.83, 1.64–2.05), poor adherence to treatment (OR 2.51, 2.21–2.86), and allergen exposure (OR 1.63, 1.47–1.81).

Conclusions

This study indicated that the presence of risk factors for poor asthma outcomes listed by the Global Initiative for Asthma document significantly influenced actual control level in a real-world large patient cohort, with high SABA use, previous severe exacerbation, incorrect inhaler technique, persistently low FEV₁, and poor adherence to treatment having the highest impact.

Chronic exposure to urban air pollution from Buenos Aires: the ocular mucosa as an early biomarker

Air pollution represents a major health problem in megacities, bringing about 8 million deaths every year. The aim of the study was to evaluate in vivo the ocular and respiratory mucosa biological response after chronic exposure to urban air particles from Buenos Aires (UAP-BA). BALB/c mice were exposed to UAP-BA or filtered air for 1, 6, 9, and 12 months. After exposure, histology, histomorphometry, and IL-6 proinflammatory cytokine level were evaluated in the respiratory and ocular mucosa. Total cell number and differential cell count were determined in the brochoalveolar lavage fluid. In the lung, chronic exposure to UAP-BA induced reduction of the alveolar space, polymorhonuclear cell recruitment, and goblet cell hyperplasia. In the ocular surface, UAP-BA induced an initial mucin positive cells rise followed by a decline through time, while IL-6 level increased at the latest point-time assayed. Our results showed that the respiratory and the ocular mucosas respond differently to UAP-BA. Being that lung and ocular mucosa diseases may be triggered and/or exacerbated by chronic exposure to urban air PM, the inhabitants of Buenos Aires whom are chronically exposed to environmental urban air pollution may be considered a subpopulation at risk. Based on our results, we propose the ocular mucosa as a reliable and more accessible surrogate for pulmonary mucosa environmental toxicity that might also serve as an earlier biomarker for air pollution adverse impact on health.

Predicting admissions for adult asthma exacerbations in North Texas

OBJECTIVES

The purpose of this study was to provide a picture of asthma disparities and the contributions of social and environmental factors to asthma exacerbations in the north central region of Texas, where intense, rapid development is a feature of contemporary life.

DESIGN AND SAMPLE

Cross-sectional analysis of data associated with 66 hospitals in the 8 counties containing and surrounding the Dallas/Fort Worth metropolitan area. Census blocks containing adult asthma patients admitted to emergency departments (ED) or inpatient units for asthma exacerbations in 2014.

MEASURES

Data for secondary analysis were collected from the Dallas Fort Worth Hospital Council Foundation.

RESULTS

Sex, family income, education, race, age of housing, speed, and traffic density on neighborhood roads affected asthma admissions. Proximity to urban drilling sites had only a small effect on admissions in this sample. Minorities were significantly more likely to obtain services in the ED than whites.

CONCLUSIONS

Attributes associated with poor and underserved patients predicted asthma exacerbations in the target region. These are vulnerable patients who can ill afford further erosion of health care insurance or additional environmental insults.

Uncertainties in Model-Based Diesel Particulate Filter Diagnostics Using a Soot Sensor

Monitoring the filtration efficiency of the diesel particulate filter (DPF), is a legislative requirement for minimizing particulate matter (PM) emissions from diesel engines of passenger cars and heavy-duty vehicles. To reach this target, on-board diagnostics (OBD) in real-time operation are required. Such systems in passenger cars are often utilizing a soot sensor, models for PM emissions simulation and algorithms for diagnosis. Their performance is associated with a series of challenges related to the accuracy and effectiveness of involved models, algorithms and hardware. This paper analyzes the main influencing factors and their impact on the effectiveness of the OBD system. The followed method comprised an error propagation analysis to quantify the error of detection during a New European Driving Cycle (NEDC). The results of the study regarding the performance of the OBD model showed that the total error of diagnosis is ±28%. This performance can be improved by increasing the sensor accuracy and the soot model, which can make the model appropriate for even tighter legislation limits and other approaches such as on-board monitoring (OBM).

The Role of Socioeconomic Status in the Association of Lung Function and Air Pollution-A Pooled Analysis of Three Adult ESCAPE Cohorts

Ambient air pollution is a leading environmental risk factor and its broad spectrum of adverse health effects includes a decrease in lung function. Socioeconomic status (SES) is known to be associated with both air pollution exposure and respiratory function. This study assesses the role of SES either as confounder or effect modifier of the association between ambient air pollution and lung function. Cross-sectional data from three European multicenter adult cohorts were pooled to assess factors associated with lung function, including annual means of home outdoor NO₂. Pre-bronchodilator lung function was measured according to the ATS-criteria. Multiple mixed linear models with random intercepts for study areas were used. Three different factors (education, occupation and neighborhood unemployment rate) were considered to represent SES. NO₂ exposure was negatively associated with lung function. Occupation and neighborhood unemployment rates were not associated with lung function. However, the inclusion of the SES-variable education improved the models and the air pollution-lung function associations got slightly stronger. NO₂ associations with lung function were not substantially modified by SES-variables. In this multicenter European study we could show that SES plays a role as a confounder in the association of ambient NO₂ exposure with lung function.