The priming effect of diesel exhaust on native pollen exposure at the air-liquid interface

Toxicological effects of long-term continuous exposure to ambient air on human bronchial epithelial Calu-3 cells exposed at the air-liquid interface

Air pollution significantly contributes to the global burden of respiratory and cardiovascular diseases. While single source/compound studies dominate current research, long-term, multi-pollutant studies are crucial to understanding the health impacts of environmental aerosols. Our study aimed to use the first air-liquid interface (ALI) aerosol exposure system adapted for long-term in vitro exposures for ambient air in vitro exposure. The automated exposure system was adapted to enable long-term cell exposure. ALI human bronchial epithelial cells (Calu-3) were continuously exposed for 72 h to the ambient air from a European urban area (3 independent exposures). Experimental evaluation included comprehensive toxicological assessments coupled to physical and chemical characterization of the aerosol. Exposure to ambient air resulted in increased significant cytotoxicity and a non-significant decrease in cell viability. Differential gene expressions were indicated for genes related to inflammation (IL1B, IL6) and to xenobiotic metabolism (CYP1A1, CYP1B1) with possible correlations to the PM2.5 content. Common air pollutants were identified such as the carcinogenic benz[a]pyrene (≤3.4 ng m-3/24h) and PM2.5 (≤11.6 μg m-3/24h) with a maximum particle number mean of 4.4 × 10-3 m3/24h. For the first time, ALI human lung epithelial cells were exposed for 72 h to continuous airflow of ambient air. Despite direct exposure to ambient aerosols, only small decrease in cell viability and gene expression changes was observed. We propose this experimental set-up combining comprehensive aerosol characterization and long-term continuous ALI cell exposure for the identification of hazardous compounds or compound mixtures in ambient air.

Real-world outdoor air exposure effects in a model of the human airway epithelium - A comparison of healthy and asthmatic individuals using a mobile laboratory setting

We developed a mobile laboratory allowing field exposure of lung tissue models to ambient air at localities with various pollution sources (Background, Industrial, Traffic, Urban) in different seasons (summer/fall/winter). In samples originating from healthy and asthmatic individuals, we assessed the parameters of toxicity, lipid peroxidation and immune response; we further performed comprehensive monitoring of air pollutants at sampling sites. We measured lactate dehydrogenase (LDH) and adenylate kinase (AK) production and transepithelial electrical resistance (TEER), analyzed 15-F2t-isopostane (IsoP) and a panel of 20 cytokines/chemokines/growth factors. In the ambient air, we detected particulate matter (PM), and other relevant chemicals (benzene, benzo[a]pyrene (BaP), NOx). In the Traffic locality, we found very high concentrations of ultrafine particles and NOx and observed low TEER values in the exposed samples, indicating significant traffic-related toxicity of the ambient air. In the Urban locality, sampled in winter, we observed high PM and BaP levels. We found lower AK levels in samples from healthy individuals exposed in this locality than in the asthmatic samples. In the samples from the Industrial locality, sampled in summer, we detected higher concentrations of TNFα, MIP-1α, Eotaxin, GROα, GM-CSF, IL-6 and IL-7 than in the Urban locality samples. We hypothesize that pollen or other plant-related components of the ambient air were responsible for this response. In conclusion, our data proved the feasibility of our mobile laboratory for field measurements of the biological response of lung tissue models exposed to ambient air, reflecting not only the levels of toxic compounds, but also season-specific parameters.

Global change, climate change, and asthma in children: Direct and indirect effects - A WAO Pediatric Asthma Committee Report

The twenty-first century has seen a fundamental shift in disease epidemiology with anthropogenic environmental change emerging as the likely dominant factor affecting the distribution and severity of current and future human disease. This is especially true of allergic diseases and asthma with their intimate relationship with the natural environment. Climate change-related variables including increased ambient temperature, heat waves, extreme weather events, air pollution, and rainfall distribution, all can directly affect asthma in children, but each of these variables also indirectly affects asthma via alterations in pollen production and release, outdoor allergen exposure or the microbiome. Air pollution, with its many and varied respiratory consequences, is likely to have the greatest effect, as it has increased globally due to rapid increases in fossil fuel combustion, global population, crowding, and megacities, as well as forest burning and trees succumbing to an increasingly hostile environment. Human activities have also caused substantial deterioration of the global microbiome with reductions in biodiversity for molds, bacteria, and viruses. Reduced microbiome diversity has, in turn, been associated with increases in Th2 allergic responses and allergic disease. The collective effect of these changes has already shifted allergy and asthma disease patterns. Given that changes in climate have been relatively small to date, the unavoidable, much greater shifts in climate in the future are concerning. Determining the relative scale of the direct versus indirect effects of climate change variables is needed if effective avoidance and adaptive measures are to be implemented. This would also require much more basic, epidemiological, and clinical research to understand the causal mechanisms, the most relevant climate factors involved, the regions most affected and, most importantly, effective and actionable adaptation measures. We suggest that allergy and respiratory health workers should follow current guidance to reduce present risks related to climate change and watch for new recommendations to reduce future risks. Since the respiratory system is the one most affected by climate change, they also need to call for more research in this area and show strong leadership in advocating for urgent action to protect children by reducing or reversing factors that have led to our deteriorating climate.

Mapping pollen allergenicity from urban trees in Valencia: A tool for green infrastructure planning

Urban trees provide many benefits to citizens but also have associated disservices such as pollen allergenicity. Pollen allergies affect 40% of the European population, a problem that will be exacerbated with climate change by lengthening the pollen season. The allergenic characteristics of the urban trees and urban parks of the city of Valencia (Spain) have been studied. The Value of Potential Allergenicity (VPA) was calculated for all species. The most abundant allergenic trees with a very high VPA were the cypresses, followed by Platanus x hispanica and species of genera Morus, Acer and Fraxinus, with a high VPA. On the contrary, Citrus x aurantium, Melia azedarach, Washingtonia spp., Brachychiton spp. and Jacaranda mimosifolia were among the most abundant low allergenic trees. VPA was mapped for the city and a hot spot analysis was applied to identify areas of clustering of high and low VPA values. This geostatistical analysis provides a comprehensive representation of the VPA patterns which is very useful for urban green infrastructure planning. The Index of Urban Green Zone Allergenicity (IUGZA) was calculated for the main parks of the city. The subtropical and tropical flora component included many entomophilous species and the lowest share of high and very high allergenic trees in comparison with the Mediterranean and Temperate components. Overall, a diversification of tree species avoiding clusters of high VPA trees, and the prioritization of species with low VPA are good strategies to minimize allergy-related impacts of urban trees on human health.

Dissecting Airborne Allergens

Asthma is a heterogeneous and very complex group of diseases, and includes different clinical phenotypes depending on symptoms, progression, exacerbation patterns, or responses to treatment, among other characteristics. The allergic phenotype is the most frequent, especially in pediatric asthma. It is characterized by sensitization (the production of specific IgEs) to allergens and frequent comorbidity with rhinitis as well as atopic dermatitis. Given the complexity of allergic asthma, knowledge of it must be approached from different points of view: clinical, histological, physiological, epidemiological, biochemical, and immunological, among others. Since partial approaches do not allow for the understanding of this complexity, it is necessary to have multidimensional knowledge that helps in performing the optimal management of each case, avoiding a "blind men and elephant parable" approach. Allergens are antigens that trigger the production of specific IgE antibodies in susceptible individuals, who present symptoms that will depend on the type and intensity of the allergenic load as well as the tissue where the interaction occurs. Airborne allergens cause their effects in the respiratory tract and eyes, and can be indoor or outdoor, perennial, or seasonal. Although allergens such as mites, pollens, or animal dander are generally considered single particles, it is important to note that they contain different molecules which could trigger distinct specific IgE molecules in different patients. General practitioners, pediatricians, and other physicians typically diagnose and treat asthma based on clinical and pulmonary function data in their daily practice. This nonsystematic and nonexhaustive revision aims to update other topics, especially those focused on airborne allergens, helping the diagnostic and therapeutic processes of allergic asthma and rhinitis.

Development and Characterization of a 96-Well Exposure System for Safety Assessment of Nanomaterials

In this study, a 96-well exposure system for safety assessment of nanomaterials is developed and characterized using an air-liquid interface lung epithelial model. This system is designed for sequential nebulization. Distribution studies verify the reproducible distribution over all 96 wells, with lower insert-to-insert variability compared to non-sequential application. With a first set of chemicals (TritonX), drugs (Bortezomib), and nanomaterials (silver nanoparticles and (non-)fluorescent crystalline nanocellulose), sequential exposure studies are performed with human lung epithelial cells followed by quantification of the deposited mass and of cell viability. The developed exposure system offers for the first time the possibility of exposing an air-liquid interface model in a 96-well format, resulting in high-throughput rates, combined with the feature for sequential dosing. This exposure system allows the possibility of creating dose-response curves resulting in the generation of more reliable cell-based assay data for many types of applications, such as safety analysis. In addition to chemicals and drugs, nanomaterials with spherical shapes, but also morphologically more complex nanostructures can be exposed sequentially with high efficiency. This allows new perspectives on in vivo-like and animal-free approaches for chemical and pharmaceutical safety assessment, in line with the 3R principle of replacing and reducing animal experiments.

Biological impact of sequential exposures to allergens and ultrafine particle-rich combustion aerosol on human bronchial epithelial BEAS-2B cells at the air liquid interface

The prevalence of allergic diseases is constantly increasing since few decades. Anthropogenic ultrafine particles (UFPs) and allergenic aerosols is highly involved in this increase; however, the underlying cellular mechanisms are not yet understood. Studies observing these effects focused mainly on singular in vivo or in vitro exposures of single particle sources, while there is only limited evidence on their subsequent or combined effects. Our study aimed at evaluating the effect of subsequent exposures to allergy-related anthropogenic and biogenic aerosols on cellular mechanism exposed at air-liquid interface (ALI) conditions. Bronchial epithelial BEAS-2B cells were exposed to UFP-rich combustion aerosols for 2 h with or without allergen pre-exposure to birch pollen extract (BPE) or house dust mite extract (HDME). The physicochemical properties of the generated particles were characterized by state-of-the-art analytical instrumentation. We evaluated the cellular response in terms of cytotoxicity, oxidative stress, genotoxicity, and in-depth gene expression profiling. We observed that single exposures with UFP, BPE, and HDME cause genotoxicity. Exposure to UFP induced pro-inflammatory canonical pathways, shifting to a more xenobiotic-related response with longer preincubation time. With additional allergen exposure, the modulation of pro-inflammatory and xenobiotic signaling was more pronounced and appeared faster. Moreover, aryl hydrocarbon receptor (AhR) signaling activation showed to be an important feature of UFP toxicity, which was especially pronounced upon pre-exposure. In summary, we were able to demonstrate the importance of subsequent exposure studies to understand realistic exposure situations and to identify possible adjuvant allergic effects and the underlying molecular mechanisms.

Processing of carbon-reinforced construction materials releases PM2.5 inducing inflammation and (secondary) genotoxicity in human lung epithelial cells and fibroblasts

Building demolition following domestic fires or abrasive processing after thermal recycling can release particles harmful for the environment and human health. To mimic such situations, particles release during dry-cutting of construction materials was investigated. A reinforcement material consisting of carbon rods (CR), carbon concrete composite (C³) and thermally treated C³ (ttC³) were physicochemically and toxicologically analyzed in monocultured lung epithelial cells, and co-cultured lung epithelial cells and fibroblasts at the air-liquid interface. C³ particles reduced their diameter to WHO fibre dimensions during thermal treatment. Caused by physical properties or by polycyclic aromatic hydrocarbons and bisphenol A found in the materials, especially the released particles of CR and ttC³ induced an acute inflammatory response and (secondary) DNA damage. Transcriptome analysis indicated that CR and ttC³ particles carried out their toxicity via different mechanisms. While ttC³ affected pro-fibrotic pathways, CR was mostly involved in DNA damage response and in pro-oncogenic signaling.

Risk assessment of pollen allergy in urban environments

According to WHO, by 2050, at least one person out of two will suffer from an allergy disorder resulting from the accelerating air pollution associated with toxic gas emissions and climate change. Airborne pollen, and associated allergies, are major public health topics during the pollination season, and their effects are further strengthened due to climate change. Therefore, assessing the airborne pollen allergy risk is essential for improving public health. This study presents a new computational fluid dynamics methodology for risk assessment of local airborne pollen transport in an urban environment. Specifically, we investigate the local airborne pollen transport from trees on a university campus in the north of France. We produce risk assessment maps for pollen allergy for five consecutive days during the pollination season. The proposed methodology could be extended to larger built-up areas for different weather conditions. The risk assessment maps may also be integrated with smart devices, thus leading to decision-aid tools to better guide and protect the public against airborne pollen allergy.