Mechanism of asthmatic exacerbation by ambient air pollution particles

Effect of GHX02 on an Asthma-Rhinitis Mouse Model Induced by Ovalbumin and Diesel Particulate Matter

Fine dust concentrations come in direct contact with the human respiratory system, thereby reducing lung function and causing respiratory diseases such as asthma and rhinitis. The aim of this study was to evaluate the efficacy of GHX02 (combination of four herbs [Trichosanthes kirilowii, Prunus armeniaca, Coptis japonica, and Scutellaria baicalensis]), a herbal extract with established efficacy against bronchitis and pulmonary disease, in the treatment of asthma accompanied by rhinitis aggravated by fine dust. Therefore, we constructed an asthma-rhinitis mouse model of Balb/c mice challenged with ovalbumin (OVA) and fine diesel particulate matter, which were administered with three concentrations of GHX02. GHX02 significantly inhibited the increase of total cells and immune cells in bronchoalveolar lavage fluid, lung tissue, and nasal ductal lymphoid tissue (NALT). GHX02 also reduced the severity of histological lung injury and the expression of interleukin (IL)-1α and nuclear factor kappa B (NF-κB), which regulate inflammatory responses. The results indicate that GHX02 inhibited the inflammatory immune response in mice. Therefore, this study highlights the potential of GHX02 as a treatment for patients with asthma accompanied by rhinitis. Balb/c mice were challenged with OVA and PM10D, and then treated with three concentration of GHX02. GHX02 significantly inhibited the increase of total cells, immune cells lymphocytes, neutrophils, and macrophages, as well as their expression in lung tissue. GHX02 significantly inhibited the increase of total cells and immune cells in NALT. GHX02 decreased the severity of histological lung injury, expression of IL-1α and NF-κB. This study suggests the probability that GHX02 is effective for asthma patients with rhinitis by inhibiting inflammatory immune response.

"Air That Once Was Breath" Part 1: Wildfire-Smoke-Induced Mechanisms of Airway Inflammation - "Climate Change, Allergy and Immunology" Special IAAI Article Collection: Collegium Internationale Allergologicum Update 2023

BACKGROUND

Wildfires are a global concern due to their wide-ranging environmental, economic, and public health impacts. Climate change contributes to an increase in the frequency and intensity of wildfires making smoke exposure a more significant and recurring health concern for individuals with airway diseases. Some of the most prominent effects of wildfire smoke exposure are asthma exacerbations and allergic airway sensitization. Likely due to the delayed recognition of its health impacts in comparison with cigarette smoke and industrial or traffic-related air pollution, research on the composition, the mechanisms of toxicity, and the cellular/molecular pathways involved is poor or non-existent.

SUMMARY

This review discusses potential underlying pathological mechanisms of wildfire-smoke-related allergic airway disease and asthma. We focused on major gaps in understanding the role of wildfire smoke composition in the development of airway disease and the known and potential mechanisms involving cellular and molecular players of oxidative injury at the epithelial barrier in airway inflammation. We examine how PM2.5, VOCs, O3, endotoxin, microbes, and toxic gases may affect oxidative stress and inflammation in the respiratory mucosal barrier. We discuss the role of AhR in mediating smoke's effects in alarmin release and IL-17A production and how glucocorticoid responsiveness may be impaired by IL-17A-induced signaling and epigenetic changes leading to steroid-resistant severe airway inflammation.

KEY MESSAGE

Effective mitigation of wildfire-smoke-related respiratory health effects would require comprehensive research efforts aimed at a better understanding of the immune regulatory effects of wildfire smoke in respiratory health and disease.

IL-23 contributes to Particulate Matter induced allergic asthma in the early life of mice and promotes asthma susceptibility

Air pollutant exposure leads to and exacerbates respiratory diseases. Particulate Matter (PM) is a major deleterious factor in the pathophysiology of asthma. Nonetheless, studies on the effects and mechanisms of exposure in the early life of mice remain unresolved. This study aimed to investigate changes in allergic phenotypes and effects on allergen-specific memory T cells resulting from co-exposure of mice in the early life to PM and house dust mites (HDM) and to explore the role of interleukin-23 (IL-23) in this process. PM and low-dose HDM were administered intranasally in 4-day-old C57BL/6 mice. After confirming an increase in IL-23 expression in mouse lung tissues, changes in the asthma phenotype and lung effector/memory Th2 or Th17 cells were evaluated after intranasal administration of anti-IL-23 antibody (Ab) during co-exposure to PM and HDM. Evaluation was performed up to 7 weeks after the last administration. Co-exposure to PM and low-dose HDM resulted in increases in airway hyperresponsiveness (AHR), eosinophils, neutrophils, and persistent Th2/Th17 effector/memory cells, which were all inhibited by anti-IL-23 Ab administration. When low-dose HDM was administered twice after a 7-week rest, mice exposed to PM and HDM during the previous early life period exhibited re-increases AHR, eosinophil count, HDM-specific IgG1, and effector/memory Th2 and Th17 cell populations. However, anti-IL-23 Ab administration during the early life period resulted in inhibition. Co-exposure to PM and low-dose HDM reinforced the allergic phenotypes and allergen-specific memory responses in early life of mice. During this process, IL-23 contributes to the enhancement of effector/memory Th2/Th17 cells and allergic phenotypes. KEY MESSAGES: PM-induced IL-23 expression, allergic responses in HDMinstilled mice of early life period. PM-induced effector/memory Th2/Th17 cells in HDMinstilled mice of early life period. Inhibition of IL-23 reduced the increase in allergic responses. Inhibition of IL-23 reduced the increase in allergic responses. After the resting period, HDM administration showed re-increase in allergic responses. Inhibition of IL-23 reduced the HDM-recall allergic responses.

Environmental pollutants increase the risks of acute exacerbation in patients with chronic airway disease

Objective

Respiratory infections are a common cause of acute exacerbations in patients with chronic airway disease, however, environmental factors such as air pollution can also contribute to these exacerbations. The study aimed to determine the correlation between pollutant levels and exacerbation risks in areas exposed to environmental pollution sources.

Methods

From 2015 to 2016, a total of 788 patients with chronic airway diseases were enrolled in a study. Their medical records, including hospital visits due to acute exacerbations of varying severity were analyzed. Additionally, data on daily pollutant levels from the Air Quality Monitoring Network from 2014 to 2016 was also collected and analyzed.

Results

Patients with chronic airway disease and poor lung function (FEV1 < 50% or obstructive ventilatory defect) have a higher risk of severe acute exacerbations and are more likely to experience more than two severe acute exacerbations within a year. The study found that in areas exposed to environmental pollution sources, there is a significant correlation between NO2, O3, and humidity with the main causes of severe acute exacerbation. When the levels of NO2 were higher than 16.65 ppb, O3 higher than 35.65 ppb, or humidity higher than 76.95%, the risk of severe acute exacerbation in patients with chronic airway disease increased.

Conclusion

Acute exacerbations of chronic airway disease can be triggered by both the underlying disease state and the presence of air pollution. Computer simulations and early warning systems should be developed to predict acute exacerbations of chronic airway disease based on dynamic changes in air pollution.

Short-term associations of low-level fine particulate matter (PM2.5) with cardiorespiratory hospitalizations in 139 Japanese cities

There have been few studies in non-western countries on the relationship between low levels of daily fine particulate matter (PM_2.5) exposure and morbidity or mortality, and the impact of PM_2.5 concentrations below 15 μg/m³, which is the latest World Health Organization Air Quality Guideline (WHO AQG) value for the 24-h mean, is not yet clear. We assessed the associations between low-level PM_2.5 exposure and cardiorespiratory admissions in Japan. We collected the daily hospital admission count data, air pollutant data, and meteorological condition data recorded from April 2016 to March 2019 in 139 Japanese cities. City-specific estimates were obtained from conditional logistic regression models in a time-stratified case-crossover design and pooled by random-effect models. We estimated that every 10-μg/m³ increase in the concurrent-day PM_2.5 concentration was related to a 0.52% increase in cardiovascular admissions (95% CI: 0.13-0.92%) and a 1.74% increase in respiratory admissions (95% CI: 1.41-2.07%). These values were nearly the same when the datasets were filtered to contain only daily PM_2.5 concentrations <15 μg/m³. The exposure-response curves showed approximately sublinear-to-linear curves with no indication of thresholds. These associations with cardiovascular diseases weakened after adjusting for nitrogen dioxide or sulfur dioxide, but associations with respiratory diseases were almost unchanged when additionally adjusted for other pollutants. This study demonstrated that associations between daily PM_2.5 and daily cardiorespiratory hospitalizations might persist at low concentrations, including those below the latest WHO AQG value. Our findings suggest that the updated guideline value may still be insufficient from the perspective of public health.

Associations of short-term exposure to air pollution and emergency department visits for pediatric asthma in Shanghai, China

There is limited evidence regarding the relationship between air pollution and pediatric asthma in developing countries. This study aimed to investigate the association between short-term exposure to ambient air pollutants and pediatric asthma emergency department (ED) visits in Shanghai, China. We collected data on six criteria air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, CO, and O₃) and daily ED visits for pediatric asthma patients from 66 hospitals in Shanghai from 2016 to 2018. The generalized additive model combined with polynomial distributed lag model was applied to explore the associations. We fitted two-pollutant models and stratified the analyses by sex, age, and season. In total, we identified 108,817 emergency department visits for pediatric asthma. A 10 μg/m³ increase in the concentrations of PM_2.5, NO₂, SO₂, and O₃ was significantly associated with increased risks of pediatric asthma ED visits, with relative risk of pediatric asthma of 1.011 [95% confidence interval (CI): 1.002, 1.021], 1.030 (95%CI: 1.017, 1.043), 1.106 (95%CI: 1.041, 1.174), and 1.009 (95%CI: 1.001, 1.017), respectively. The associations of NO₂ remained robust in the two-pollutant models. There were stronger associations for older children (6-18 years) and in warm seasons. The concentration-response curves for pediatric asthma and PM_2.5, NO₂, SO₂, and O₃ were steeper at lower and moderate concentrations but became flatter at higher concentrations. This analysis provided evidence that short-term exposure to air pollutants (PM_2.5, NO₂, SO₂, and O₃) could increase the risk of asthma exacerbations among children, and health benefits would be gained from improved air quality.

Metal nanomaterials: Immune effects and implications of physicochemical properties on sensitization, elicitation, and exacerbation of allergic disease

The recent surge in incorporation of metallic and metal oxide nanomaterials into consumer products and their corresponding use in occupational settings have raised concerns over the potential for metals to induce size-specific adverse toxicological effects. Although nano-metals have been shown to induce greater lung injury and inflammation than their larger metal counterparts, their size-related effects on the immune system and allergic disease remain largely unknown. This knowledge gap is particularly concerning since metals are historically recognized as common inducers of allergic contact dermatitis, occupational asthma, and allergic adjuvancy. The investigation into the potential for adverse immune effects following exposure to metal nanomaterials is becoming an area of scientific interest since these characteristically lightweight materials are easily aerosolized and inhaled, and their small size may allow for penetration of the skin, which may promote unique size-specific immune effects with implications for allergic disease. Additionally, alterations in physicochemical properties of metals in the nano-scale greatly influence their interactions with components of biological systems, potentially leading to implications for inducing or exacerbating allergic disease. Although some research has been directed toward addressing these concerns, many aspects of metal nanomaterial-induced immune effects remain unclear. Overall, more scientific knowledge exists in regards to the potential for metal nanomaterials to exacerbate allergic disease than to their potential to induce allergic disease. Furthermore, effects of metal nanomaterial exposure on respiratory allergy have been more thoroughly-characterized than their potential influence on dermal allergy. Current knowledge regarding metal nanomaterials and their potential to induce/exacerbate dermal and respiratory allergy are summarized in this review. In addition, an examination of several remaining knowledge gaps and considerations for future studies is provided.

Short-term effects of ambient PM1 and PM2.5 air pollution on hospital admission for respiratory diseases: Case-crossover evidence from Shenzhen, China

BACKGROUND

Ambient PM₁ (particulate matter with aerodynamic diameter ≤1 μm) is an important contribution of PM_2.5 mass. However, little is known worldwide regarding the PM₁-associated health effects due to a wide lack of ground-based PM₁ measurements from air monitoring stations.

METHODS

We collected daily records of hospital admission for respiratory diseases and station-based measurements of air pollution and weather conditions in Shenzhen, China, 2015-2016. Time-stratified case-crossover design and conditional logistic regression models were adopted to estimate hospitalization risks associated with short-term exposures to PM₁ and PM_2.5.

RESULTS

PM₁ and PM_2.5 showed significant adverse effects on respiratory disease hospitalizations, while no evident associations with PM_1-2.5 were identified. Admission risks for total respiratory diseases were 1.09 (95% confidence interval: 1.04 to 1.14) and 1.06 (1.02 to 1.10), corresponding to per 10 μg/m³ rise in exposure to PM₁ and PM_2.5 at lag 0-2 days, respectively. Both PM₁ and PM_2.5 were strongly associated with increased admission for pneumonia and chronic obstructive pulmonary diseases, but exhibited no effects on asthma and upper respiratory tract infection. Largely comparable risk estimates were observed between male and female patients. Groups aged 0-14 years and 45-74 years were significantly affected by PM₁- and PM_2.5-associated risks. PM-hospitalization associations exhibited a clear seasonal pattern, with significantly larger risks in cold season than those in warm season among some subgroups.

CONCLUSIONS

Our study suggested that PM₁ rather than PM_1-2.5 contributed to PM_2.5-induced risks of hospitalization for respiratory diseases and effects of PM₁ and PM_2.5 mainly occurred in cold season.

Assessment of the Air Quality Health Index (AQHI) and four alternate AQHI-Plus amendments for wildfire seasons in British Columbia

OBJECTIVE

Wildfire smoke is an important source of air pollution associated with a range of cardiopulmonary health conditions. The Air Quality Health Index (AQHI) is the most widely used tool in Canada to communicate with the public about air pollution, but it may not adequately reflect health risks from wildfire smoke. The objective of this study was to evaluate the ability of the AQHI and four alternate AQHI-Plus amendments to predict adverse population health effects from wildfire smoke.

METHODS

The maximum 1-h values of the AQHI and the four amendments were calculated for each 48-h period of the wildfire seasons from 2010 to 2017 for 32 health units in British Columbia. Generalized Poisson models were used to estimate the association between these values and daily counts of five health outcomes: all-cause mortality; physician visits for all circulatory causes; visits for all respiratory causes, including asthma; asthma-specific visits; and dispensations of salbutamol sulfate (i.e., Ventolin®). Model fit was evaluated with the Akaike information criterion.

RESULTS

The AQHI and the four amendments were all associated with all five health outcomes. The AQHI exhibited best fit to the all-cause mortality and circulatory physician visits during all wildfire seasons, while the 1-h PM_2.5Only AQHI-Plus exhibited best fit to the asthma-related outcomes during all wildfire seasons.

CONCLUSION

Individuals with common respiratory conditions such as asthma and chronic obstructive pulmonary disease are particularly susceptible to wildfire smoke. As such, the 1-h PM_2.5Only AQHI-Plus amendment was recommended for communicating about potential health effects of air quality during wildfire seasons in BC.

Air pollution and asthma attacks in children: A case-crossover analysis in the city of Chongqing, China

Data on particulate matter of diameter <2.5 μm (PM_2.5) in the city of Chongqing were first announced in 2013. We wished to assess the effects of pollutants on asthmatic children in Chongqing, China. Daily numbers of hospital visits because of asthma attacks in children aged 0-18 years in 2013 were collected from the Children's Hospital of Chongqing Medical University. Data on pollutants were accessed from the nine air quality-monitoring stations in Chongqing. A time-stratified case-crossover design was applied and conditional logistic regression was undertaken to analyze the data. We found that short-term exposure to PM₁₀, PM_2.5, sodium dioxide, nitrogen and carbon monoxide could trigger hospital visits for asthma in children. Nitrogen dioxide had an important role, whereas ozone had no effect.

Co-occurrence of autism and asthma in a nationally-representative sample of children in the United States

Few large epidemiological studies have examined the co-occurrence of autism and asthma. We performed a cross-sectional study to examine this association using the 2007 National Survey of Children's Health dataset (n = 77,951). We controlled for confounders and tested for autism-secondhand smoke interaction. Prevalence of asthma and autism were 14.5 % (n = 11,335) and 1.81 % (n = 1,412) respectively. Unadjusted odds ratio (OR) for asthma among autistic children was 1.35 (95 % CI 1.18-1.55). Adjusting for covariates (age, gender, body mass index, race, brain injury, secondhand smoke and socio-economic status) attenuated the OR to 1.19 (95 % CI 1.03-1.36). Autism-secondhand smoke interaction was insignificant (p = 0.38). Asthma is approximately 35 % more common in autistic children; screening may be an efficient approach to reduce risk of morbidity due to asthma.

Association of mechanical ventilation and flue use in heaters with asthma symptoms in Japanese schoolchildren: a cross-sectional study in Sapporo, Japan

Background

Use of fuel heaters is associated with childhood asthma. However, no studies have evaluated the associations of flue use and mechanical ventilation (ventilation) with asthma symptoms in schoolchildren.

Methods

This cross-sectional study investigated schoolchildren in grades 1 through 6 (age 6–12 years) in Sapporo, Japan. From November 2008 through January 2009, parents completed questionnaires regarding their home environment and their children’s asthma symptoms.

Results

In total, 4445 (69.5%) parents of 6393 children returned the questionnaire. After excluding incomplete responses, data on 3874 children (60.6%) were analyzed. The prevalence of current asthma symptoms and ever asthma symptoms were 12.8% and 30.9%, respectively. As compared with electric heaters, current asthma symptoms was associated with use of flued heaters without ventilation (OR = 1.62; 95% CI, 1.03–2.64) and unflued heaters with ventilation (OR = 1.77; 95% CI, 1.09–2.95) or without ventilation (OR = 2.23; 95% CI, 1.31–3.85). Regardless of dampness, unflued heaters were significantly associated with current asthma symptoms in the presence and absence of ventilation.

Conclusions

Use of unflued heaters was associated with current asthma symptoms, regardless of dampness. In particular, the prevalence of current asthma symptoms was higher in the absence of ventilation than in the presence of ventilation. Ever asthma symptoms was only associated with use of unflued heaters without ventilation. Consequently, use of fuel heaters, especially those that have no flue or ventilation, deserves attention, as their use might be associated with childhood asthma symptoms.