The relationship between PM2.5 and the onset and exacerbation of childhood asthma: a short communication

Live bacteria in gut microbiome dictate asthma onset triggered by environmental particles via modulation of DNA methylation in dendritic cells

Despite broad knowledge of the pathogenesis, our understanding of the origin of allergy and asthma remains poor, preventing etiotropic treatments. The gut microbiome is seen to be altered in asthmatics; however, proof of causality of the microbiome alterations is lacking. We report on gut microbiome transplantation (GMT) from mice predisposed to asthma by maternal exposure to pro-allergy environmental particles into naive recipients. This GMT confers asthma predisposition, and the effect is abrogated by gamma sterilization of the transplant material or by co-administration of antibacterials, indicating that viable bacteria are mediating the effect. Metagenomics identifies key changes in the "pro-asthma" microbiome, and metabolomics links the identified species to altered production of butyrate known to act on immune cells and epigenetic mechanisms. We further show that transplant recipients develop DNA methylation alterations in dendritic cells. Finally, dendritic cells with an altered methylome present allergen to T cells, and this effect is abrogated by an epigenetically acting drug in vitro.

PM2.5 affected ciliary beat frequency of axonemes via the cyclic AMP-dependent protein kinase a pathway

Long-term inhalation of fine particulate matter (PM2.5) has been linked to the onset of various lung diseases. The mucociliary clearance system, acts as the primary host defense mechanism in the airways, with ciliary beat frequency (CBF) being a key parameter for assessing its functionality. The primary aim of this study was to demonstrate the impact of PM2.5 on CBF and to investigate the potential mechanisms by which PM2.5 induced changes in CBF through airway axonemes. Airway axonemes were extracted from bovine ciliated epithelium and treated with different concentrations of PM2.5 in vitro for 10 min and 1 h to simulate short-term and prolonged exposures. Additionally, the pathway was examined using PKA activator (cAMP) and PKA inhibitor (PKI) on ciliary axonemes. The results revealed that PM2.5 stimulated CBF in airway axonemes via the cAMP-PKA pathway. Low concentrations and short-term exposure to PM2.5 stimulated CBF elevation, however, high concentration and prolonged exposure to PM2.5 might damage respiratory cilia, thereby increasing the risk of respiratory diseases.

Effect of PM2.5 exposure on susceptibility to allergic asthma in elderly rats treated with allergens

Fine particulate matter 2.5 (PM2.5) is a prevalent atmospheric pollutant that is closely associated with asthma. Elderly patients have a high incidence of asthma with a long course of illness. Our previous studies revealed that exposure to PM2.5 diminishes lung function and exacerbates lung damage in elderly rats. In the present study, we investigated whether PM2.5 exposure influences susceptibility to allergic asthma in elderly rats. Brown-Norway elderly rats were treated with ovalbumin (OVA) for different durations before and after PM2.5 exposure. The results from pulmonary function tests and histopathology indicated that early exposure to allergens prior to PM2.5 exposure increased susceptibility to airway hyperresponsiveness and led to severe lung injury in elderly asthmatic rats. Cytokine microarray analysis demonstrated that the majority of cytokines and chemokines were upregulated in OVA-treated rats before and after PM2.5 exposure. Cytological examination showed no change in eosinophil (EOS) counts, yet the amounts of neutrophils (NEU), white blood cells (WBC), lymphocytes (LYM), and monocytes (MON) in the lung lavage fluid of OVA-treated rats were significantly higher than those in control rats before and after PM2.5 exposure, suggesting that PM2.5 affects noneosinophilic asthma in elderly rats. ELISA results from the plasma and lung lavage fluid revealed that the levels of IgG1, IgE, IgG2a and IgG2b were significantly elevated in OVA-treated rats, whereas the level of IgG2b in the lung lavage fluid was significantly lower in rats treated with OVA prior to PM2.5 exposure compared to those treated afterward. A non-targeted metabolomic analysis of plasma identified 202 metabolites, among which 31 metabolites were differentially abundant. Ten metabolites and 11 metabolic pathways were uniquely detected in OVA-treated rats before PM2.5 exposure. Specifically, there were positive or negative correlations between the levels of Th2-associated cytokines (IL-4, IL-5, and IL-13) and six metabolites in the OVA-treated group before PM2.5 exposure, whereas the levels of IL-4 and IL-5 were negatively correlated with five metabolites in the OVA-treated group after PM2.5 exposure. Our findings suggest that PM2.5 exposure could influence the susceptibility of allergic asthma in response to allergens in elderly rats, potentially through changes in plasma metabolites.

De Novo exposomic geospatial assembly of chronic disease regions with machine learning & network analysis

BACKGROUND

Determining spatial relationships between diseases and the exposome is limited by available methodologies. aPEER (algorithm for Projection of Exposome and Epidemiological Relationships) uses machine learning (ML) and network analysis to find spatial relationships between diseases and the exposome in the United States.

METHODS

Using aPEER we examined the relationship between 12 chronic diseases and 186 pollutants. PCA, K-means clustering, and map projection produced clusters of counties derived from pollutants, and the Jaccard correlation between these clusters with chronic disease geography (defined as groups of counties with high chronic disease prevalence rates) was calculated. Disease-pollution correlation matrices were used together with network analysis to identify the strongest disease-pollution relationships. Results were compared to LISA, Moran's I, univariate, elastic net, and random forest regression.

FINDINGS

aPEER produced 68,820 human interpretable maps with distinct pollution-derived regions, and acetaldehyde/benzo(a)pyrene was found to be strongly associated with hypertension (J = 0.5316, p = 3.89 × 10-208), stroke (J = 0.4517, p = 1.15 × 10-127), and diabetes mellitus (J = 0.4425, p = 2.34 × 10-127); formaldehyde/glycol ethers with COPD (J = 0.4545, p = 8.27 × 10-131); and acetaldehyde/formaldehyde with stroke mortality (J = 0.4445, p = 4.28 × 10-125). Methanol, acetaldehyde, and formaldehyde formed distinct regions in the southeast United States (which correlated with both the Stroke and Diabetes Belts) which were strongly associated with multiple chronic diseases. Pollutants predicted chronic disease geography with similar or superior areas under the curve compared to SDOH and preventive healthcare models (determined with random forest and elastic net methods). Conventional geospatial analysis methods did not identify these geospatial relationships, highlighting aPEER's utility.

INTERPRETATION

aPEER identified a pollution-defined geographical region associated with chronic disease, highlighting the role of aPEER in epidemiological and geospatial analysis, and exposomics in understanding chronic disease geography.

FUNDING

This work was primarily funded by the BPHC, NHLBI (R03 HL157890) and the CDC, and this work was funded in part by grants from the NIH (U01 HG007691, R01 HL155107, and HL166137), the American Heart Association (AHA24MERIT1185447), and the EU (HorizonHealth 2021 101057619) to JL.

Association between air pollutants and blood cell counts in pediatric patients with asthma: a retrospective observational study

BACKGROUND

Asthma is a common respiratory disease in children, and air pollution is a risk factor for pediatric asthma. However, how air pollution affects blood cells in pediatric patients with asthma remains unclear.

METHODS

This retrospective observational study, performed in 2007-2018 at a medical center, enrolled non-trauma patients aged < 17 years who visited the emergency department and had asthma. Medical records and blood cell counts, including absolute neutrophil count (ANC), eosinophil count, and platelet count were extracted. The concentrations of PM2.5, PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), and ozone (O3) were measured from 11 air-monitoring stations in Kaohsiung City.

RESULTS

One-unit increases in PM2.5 (regression coefficient: 25.618; S.E.: 5.937; p < 0.001), PM10 (19.97; 3.541; p < 0.001), NO2 (70.681; 15.857; p < 0.001), SO2 (81.694; 30.339; p = 0.007), and O3 (23.42; 8.831; p = 0.022) on lag 0-6 (7 d average) correlated positively with ANC. One-unit increases in PM2.5 (0.859; 0.357; p = 0.016), PM10 (0.728; 0.213; p = 0.001), and SO2 (4.086; 1.811; p = 0.024) on lag 0-6 correlated positively with eosinophil count. Additionally, one-unit increases in PM2.5 (0.302; 0.101; p = 0.003) and PM10 (0.229; 0.06; p < 0.001) on lag 0-6 correlated positively with platelet count. In a two-pollutant model, the impacts of PM2.5 and PMC on ANC and platelet count remained statistically significant after adjusting for other air pollutants. Additionally, PMC correlated significantly with eosinophil count after adjusting for PM2.5, NO2, SO2, and O3. Quartile increases in PM2.5 and PMC levels correlated positively with ANC, eosinophil count, and platelet count (all p for trend < 0.05).

CONCLUSIONS

PM2.5, PMC, and NO2 were independently and positively associated with ANC, PMC was positively associated with eosinophil count, and PM2.5 and PMC were positively associated with platelet count in pediatric patients with asthma. Our results highlight the relationship between air pollution and blood cell counts in pediatric patients with asthma.

Global Trends and Hotspots in the Research of the Effects of PM2.5 on Asthma: A Bibliometric and Visualized Analysis

BACKGROUND

Fine particulate matter (PM2.5) has been identified as a significant environmental and public health challenge, particularly due to its association with respiratory diseases like asthma. With the global rise in urbanization and industrialization, PM2.5-related asthma research has grown substantially over the past two decades. This study aims to provide a comprehensive bibliometric analysis to map global research trends, highlight key contributors, and identify emerging hotspots in the relationship between PM2.5 and asthma.

METHODS

We performed a bibliometric analysis using the Web of Science Core Collection database, covering research from January 2004 to September 2024. The selected studies were analyzed using CiteSpace and VOSviewer to assess publication trends, global collaborations, and research hotspots through visualized networks and co-occurrence analyses.

RESULTS

A total of 2035 publications were identified, demonstrating a steady increase in research output over the past two decades. The United States and China emerged as dominant contributors, frequently collaborating with countries like Canada, Australia, and South Korea. Key research areas focused on air quality, particulate matter exposure, and asthma exacerbation, with an increasing emphasis on indoor air pollution and long-term exposure risks. Institutional collaborations were led by prominent universities such as the University of California System and Harvard University. Additionally, research on vulnerable populations, particularly children, and the impact of early-life exposure to PM2.5 has gained attention in recent years.

CONCLUSIONS

The global research landscape on PM2.5 and asthma has expanded significantly, with growing attention to interdisciplinary approaches that combine environmental science and public health. Future studies should focus on the global burden of air pollution, particularly in low- and middle-income countries, and address the long-term health impacts of PM2.5 exposure, especially in vulnerable populations.

Quantification of Airborne Particulate Matter and Trace Element Deposition on Hedera helix and Senecio cineraria Leaves

In both developed and developing countries, atmospheric pollution with particulate matter (PM) remains an important issue. Despite the health effects of poor air quality, studies on air pollution are often limited by the high costs of continuous monitoring and the need for extensive sampling. Furthermore, these particles are often enriched with potentially toxic trace elements and organic pollutants. This study evaluates both the composition of atmospheric dust accumulated during a certain timespan on Hedera helix and Senecio cineraria leaves and the potential for their use as bio-monitors. The test plants were positioned near automatic air quality monitoring stations at four different sites with respectively high, moderate and low traffic intensity. The gravimetric deposition of PM10 and PM2.5 on leaves was compared with data recorded by the monitoring stations and related to the weather conditions reported by Argentina's National Meteorological Service. To determine the presence of trace elements enriching the PM deposited on leaves, two analytical techniques were applied: XRF (not destructive) and ICP (destructive). The results indicated that only in the unpaved street location (site 2) did PM10 and PM2.5 concentrations (90 µg m-3 and 9 µg m-3) in the air exceed more than five times WHO guidelines (15 µg m-3 and 5 µg m-3). However, several trace elements were found to be enriching PM deposited on leaves from all sites. Predominantly, increased concentrations of Cd, Cu, Ti, Mn, Zn and Fe were found, which were associated with construction, traffic and unpaved street sources. Furthermore, based on its capability to sequester above 2800 µg cm-2 of PM10, 2450 µg cm-2 of PM2.5 and trace elements, Senecio cineraria can be taken into consideration for adoption as a bio-monitor or even for PM mitigation.

Air pollution after acute bronchiolitis is a risk factor for preschool asthma: a nested case-control study

BACKGROUND

Acute bronchiolitis and air pollution are both risk factor of pediatric asthma. This study aimed to assess subsequent exposure to air pollutants related to the inception of preschool asthma in infants with acute bronchiolitis. This study aimed to assess subsequent exposure to air pollutants related to the inception of preschool asthma in infants with acute bronchiolitis.

METHODS

A nested case-control retrospective study was performed at the Kaohsiung Medical University Hospital systems between 2009 and 2019. The average concentration of PM10, PM2.5, SO2, NO, NO2, and NOX was collected for three, six, and twelve months after the first infected episode. Adjusted regression models were employed to evaluate the association between asthma and air pollution exposure after bronchiolitis.

RESULTS

Two thousand six hundred thirty-seven children with acute bronchiolitis were included. Exposure to PM10, PM2.5, SO2, NO, NO2, and NOX in the three, six, and twelve months following an episode of bronchiolitis was found to significantly increase the risk of preschool asthma in infants with a history of bronchiolitis.(OR, 95%CI: PM10 = 1.517-1.559, 1.354-1.744; PM2.5 = 2.510-2.603, 2.148-3.061; SO2 = 1.970-2.040, 1.724-2.342; ; NO = 1.915-1.950, 1.647-2.272; NO2 = 1.915-1.950, 1.647-2.272; NOX = 1.752-1.970, 1.508-2.252) In a sensitive analysis of hospitalized infants, only PM10, PM2.5, SO2, and NO were found to have significant effects during all time periods. (OR, 95%CI: PM10 = 1.613-1.650, 1.240-2.140; PM2.5 = 2.208-2.286, 1.568-3.061; SO2 = 1.679-1.622, 1.197-2.292; NO = 1.525-1.557, 1.094-2.181) CONCLUSION: The presence of ambient PM10, PM2.5, SO2 and NO in the three, six, and twelve months following an episode of acute bronchiolitis has been linked to the development of preschool asthma in infants with a history of acute bronchiolitis.