Air Pollution Exposure Impairs Airway Epithelium IFN-β Expression in Pre-School Children

Short-term air pollution exposure and risk of respiratory pathogen infections: an 11-year case-crossover study in Guangzhou, China

BACKGROUND

Limited epidemiological evidence exists on the relationship between short-term exposure to air pollutants and respiratory pathogen infections. This study investigates the association between short-term air pollution exposure and respiratory pathogen infections in Guangzhou, southern China.

METHODS

A time-stratified case-crossover study design was applied. Data from 96,927 patients with suspected respiratory pathogen infections between 2013 and 2023 were collected. The daily air pollutant concentration is obtained from the local environmental monitoring station. Logistic regression was used to assess the effect of air pollutant exposure included in the equation on the risk of respiratory pathogen infection. Generalized additive models were used to analyze the relationship between pollutant exposure and hospital visits, adjusting for potential confounders such as temperature and precipitation. Sub-group analysis was performed to estimate the reliability of the correlations among the subgroups.

RESULTS

The logistic regression model shows that PM2.5, NO2 and CO are included in the variable equation. Single-pollutant models indicate that there is a significant association between short-term exposure to NO2 and CO and an increased risk of hospital visits for respiratory infections, especially on lag day 0, while PM2.5 shows a non-linear relationship. In the multi-pollutant model, for each unit increase in NO2, the risk of hospital visits increased by 11.66%, and for CO, the risk increased by 0.64%. Subgroup analysis showed the effects were more pronounced in minors (< 18 years), while no significant gender differences were observed. Additionally, CO and NO2 interacted with PM2.5, amplifying the risk of infection.

CONCLUSION

This large-scale epidemiological study demonstrates significant associations between short-term air pollutant exposure and respiratory infections, particularly highlighting the risks of NO2 and CO exposure. The findings underscore the critical need for strengthening air quality monitoring and protection strategies in rapidly urbanizing regions, with special attention to vulnerable populations such as minors. These results provide evidence-based support for enhancing environmental health policies in metropolitan areas to better protect public health through improved air quality standards and early warning systems.

Causal association between air pollution and allergic rhinitis, asthma: a Mendelian randomization study

Backgrounds

Observational studies suggest that air pollutants, including particulate matter and nitrogen compounds, could elevate asthma and allergic rhinitis health risks. Nevertheless, the exact nature of the causal relationship between air pollution and asthma and allergic rhinitis remains unknown. This study utilizes the Mendelian randomization (MR) technique to explore the potential causal links between air pollution components (PM2.5, PM2.5-10, PM10, NO₂, and nitrogen dioxide) and the incidence of allergic rhinitis and asthma.

Methods

A MR study utilized summary statistics from GWAS that are publicly accessible. The inverse variance weighting (IVW) approach served as the foundational analysis technique. To ensure robustness, supplementary methodologies such as the weighted median, MR-Egger regression, simple mode, and weighted model were also applied. Heterogeneity was evaluated using Cochran's Q test, and the presence of pleiotropy was determined through MR-Egger regression. The MR-PRESSO test was employed for outlier detection, and the analysis's sensitivity was scrutinized via a leave-one-out strategy.

Results

The IVW technique showed a strong correlation between PM10 and asthma (OR = 0.625, 95% CI = 0.396-0.988, p = 0.044). No significant associations were found between asthma and other air pollutants such as PM2.5, PM2.5-10, NO₂, or nitrogen dioxide. Similarly, allergic rhinitis showed no causal relationships with any studied air pollution metrics. Pleiotropy was absent in the findings. Sensitivity analyses, employing the leave-one-out method, confirmed the stability of these results, unaffected by individual single nucleotide polymorphisms (SNPs).

Conclusion

This Mendelian randomization study establishes a causal link between PM10 exposure and asthma, suggesting that interventions to reduce air pollution may decelerate the adverse progression of asthma.

Prediction of Asthma Exacerbations in Children

Asthma exacerbations are common in asthmatic children, even among those with good disease control. Asthma attacks result in the children and their parents missing school and work days; limit the patient's social and physical activities; and lead to emergency department visits, hospital admissions, or even fatal events. Thus, the prompt identification of asthmatic children at risk for exacerbation is crucial, as it may allow for proactive measures that could prevent these episodes. Children prone to asthma exacerbation are a heterogeneous group; various demographic factors such as younger age, ethnic group, low family income, clinical parameters (history of an exacerbation in the past 12 months, poor asthma control, poor adherence to treatment, comorbidities), Th2 inflammation, and environmental exposures (pollutants, stress, viral and bacterial pathogens) determine the risk of a future exacerbation and should be carefully considered. This paper aims to review the existing evidence regarding the predictors of asthma exacerbations in children and offer practical monitoring guidance for promptly recognizing patients at risk.

Increased risk of emergency department presentations for bronchiolitis in infants exposed to air pollution

Air pollution has been linked to an increased risk of several respiratory diseases in children, especially respiratory tract infections. The present study aims to evaluate the association between pediatric emergency department (PED) presentations for bronchiolitis and air pollution. PED presentations due to bronchiolitis in children aged less than 1 year were retrospectively collected from 2007 to 2018 in Padova, Italy, together with daily environmental data. A conditional logistic regression based on a time-stratified case-crossover design was performed to evaluate the association between PED presentations and exposure to NO₂ , PM2.5, and PM10. Models were adjusted for temperature, relative humidity, atmospheric pressure, and public holidays. Delayed effects in time were evaluated using distributed lag non-linear models. Odds ratio for lagged exposure from 0 to 14 days were obtained. Overall, 2251 children presented to the PED for bronchiolitis. Infants' exposure to higher concentrations of PM10 and PM2.5 in the 5 days before the presentation to the PED increased the risk of accessing the PED by more than 10%, whereas high concentrations of NO₂ between 2 and 12 days before the PED presentation were associated with an increased risk of up to 30%. The association between pollutants and infants who required hospitalization was even greater. A cumulative effect of NO₂ among the 2 weeks preceding the presentation was also observed. In summary, PM and NO₂ concentrations are associated with PED presentations and hospitalizations for bronchiolitis. Exposure of infants to air pollution could damage the respiratory tract mucosa, facilitating viral infections and exacerbating symptoms.

Potential mechanisms mediating PM2.5-induced alterations of H3N2 influenza virus infection and cytokine production in human bronchial epithelial cells

Exposure to particulate matter (PM) has been associated with increased hospital admissions for influenza. Airway epithelial cells are a primary target for inhaled environmental insults including fine PM (PM_2.5) and influenza viruses. The potentiation of PM_2.5 exposure on the effects of influenza virus on airway epithelial cells has not been adequately elucidated. In this study, the effects of PM_2.5 exposure on influenza virus (H3N2) infection and downstream modulation of inflammation and antiviral immune response were investigated using a human bronchial epithelial cell line, BEAS-2B. The results showed that PM_2.5 exposure alone increased the production of pro-inflammatory cytokines including interleukin-6 (IL-6) and IL-8 but decreased the production of the antiviral cytokine interferon-β (IFN-β) in BEAS-2B cells while H3N2 exposure alone increased the production of IL-6, IL-8, and IFN-β. Importantly, prior exposure to PM_2.5 enhanced subsequent H3N2 infectivity, expression of viral hemagglutinin protein, as well as upregulation of IL-6 and IL-8, but reduced H3N2-induced IFN-β production. Pre-treatment with a pharmacological inhibitor of nuclear factor-κB (NF-κB) suppressed pro-inflammatory cytokine production induced by PM_2.5, H3N2, as well as PM_2.5-primed H3N2 infection. Moreover, antibody-mediated neutralization of Toll-like receptor 4 (TLR4) blocked cytokine production triggered by PM_2.5 or PM_2.5-primed H3N2 infection, but not H3N2 alone. Taken together, exposure to PM_2.5 alters H3N2-induced cytokine production and markers of replication in BEAS-2B cells, which in turn are regulated by NF-κB and TLR4.

Air pollution and COPD: GOLD 2023 committee report

Exposure to air pollution is a major contributor to the pathogenesis of COPD worldwide. Indeed, most recent estimates suggest that 50% of the total attributable risk of COPD may be related to air pollution. In response, the Global Initiative for Chronic Obstructive Lung Disease (GOLD) Scientific Committee performed a comprehensive review on this topic, qualitatively synthesised the evidence to date and proffered recommendations to mitigate the risk. The review found that both gaseous and particulate components of air pollution are likely contributors to COPD. There are no absolutely safe levels of ambient air pollution and the relationship between air pollution levels and respiratory events is supra-linear. Wildfires and extreme weather events such as heat waves, which are becoming more common owing to climate change, are major threats to COPD patients and acutely increase their risk of morbidity and mortality. Exposure to air pollution also impairs lung growth in children and as such may lead to developmental COPD. GOLD recommends strong public health policies around the world to reduce ambient air pollution and for implementation of public warning systems and advisories, including where possible the use of personalised apps, to alert patients when ambient air pollution levels exceed acceptable minimal thresholds. When household particulate content exceeds acceptable thresholds, patients should consider using air cleaners and filters where feasible. Air pollution is a major health threat to patients living with COPD and actions are urgently required to reduce the morbidity and mortality related to poor air quality around the world.

Air pollution and childhood asthma

PURPOSE OF REVIEW

Asthma is the most common chronic disease of childhood. Environmental exposures, such as allergens and pollutants, are ubiquitous factors associated with asthma development and asthma morbidity. In this review, we highlight the most recent studies relevant to childhood asthma risk, onset, and exacerbation related to air pollution exposure.

RECENT FINDINGS

In this article, we review current research that has been published between 2021 and 2022, demonstrating the effects of early-life exposure to key air pollutants (e.g., particulate matter (PM), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ) and ground-level ozone (O 3 ), environmental tobacco smoke, radon, and volatile organic compounds (VOC) on respiratory health.

SUMMARY

Air pollution continues to be a global burden with serious consequences related to respiratory health. Interventions aimed at reducing air pollution in the environment must be achieved in an effort to improve asthma outcomes and pediatric health.

Hydrogen peroxide attenuates rhinovirus-induced anti-viral interferon secretion in sinonasal epithelial cells

Background

Altered innate defense mechanisms, including an imbalance between oxidants and antioxidants release, have been implicated in the pathogenesis of chronic rhinosinusitis (CRS). The aim of this study is to investigate whether oxidative stress may attenuate the secretion of anti-viral interferons in human sinonasal mucosa.

Methods

The levels of H₂O₂ in nasal secretion were increased in patients with CRS with nasal polyps, compared with that of CRS patients without nasal polyps and control subjects. Normal sinonasal epithelial cells derived from healthy subjects were cultured under an air-liquid interface. The cultured cells were infected with rhinovirus 16 (RV 16) or treated with poly (I: C), TLR3 agonist, after being pretreated with an oxidative stressor, H₂O₂ or antioxidant, N-acetylcysteine (NAC). Thereafter, the expression levels of type I (IFN-β) and type III (IFN-λ1 and λ2) interferons and interferon-stimulated genes (ISGs) were evaluated with RT-qPCR, ELISA, and western blot.

Results

The data showed that the production of type I (IFN-β) and type III (IFN-λ1 and λ2) interferons and ISGs was upregulated in cells infected with RV 16 or treated with poly (I: C). However, their up-regulated expression was attenuated in cells pretreated with H₂O_2, but not inhibited in cells pretreated with NAC. In line with these data, the up-regulated expression of TLR3, RIG-1, MDA5, and IRF3 was reduced in cells pretreated with H₂O_2, but not attenuated in cells treated with NAC. Furthermore, cells transfected with Nrf2 siRNA showed decreased secretion of anti-viral interferons whereas sulforaphane treatment enhanced the secretory capacity of antiviral interferons.

Conclusions

These results suggest that the production of RV16-induced antiviral interferons may be attenuated by oxidative stress.

Risk Factors Affecting Development and Persistence of Preschool Wheezing: Consensus Document of the Emilia-Romagna Asthma (ERA) Study Group

Wheezing at preschool age (i.e., before the age of six) is common, occurring in about 30% of children before the age of three. In terms of health care burden, preschool children with wheeze show double the rate of access to the emergency department and five times the rate of hospital admissions compared with school-age asthmatics. The consensus document aims to analyse the underlying mechanisms involved in the pathogenesis of preschool wheezing and define the risk factors (i.e., allergy, atopy, infection, bronchiolitis, genetics, indoor and outdoor pollution, tobacco smoke exposure, obesity, prematurity) and the protective factors (i.e., probiotics, breastfeeding, vitamin D, influenza vaccination, non-specific immunomodulators) associated with the development of the disease in the young child. A multidisciplinary panel of experts from the Emilia-Romagna Region, Italy, addressed twelve key questions regarding managing preschool wheezing. Clinical questions have been formulated by the expert panel using the PICO format (Patients, Intervention, Comparison, Outcomes). Systematic reviews have been conducted on PubMed to answer these specific questions and formulate recommendations. The GRADE approach has been used for each selected paper to assess the quality of the evidence and the degree of recommendations. Based on a panel of experts and extensive updated literature, this consensus document provides insight into the pathogenesis, risk and protective factors associated with the development and persistence of preschool wheezing. Undoubtedly, more research is needed to improve our understanding of the disease and confirm the associations between certain factors and the risk of wheezing in early life. In addition, preventive strategies must be promoted to avoid children's exposure to risk factors that may permanently affect respiratory health.