Early life exposure to outdoor air pollution and indoor environmental factors on the development of childhood allergy from early symptoms to diseases

Air quality and wheeze symptoms in a rural children's cohort near a drying saline lake

BACKGROUND

In California, climate change and competing water demands are intensifying the desiccation of the Salton Sea, a large land-locked "sea" situated near the southeastern rural US-Mexico border region known as the Imperial Valley.

METHODS

To examine the possible effects of living near a saline lake on children's respiratory health, we analyzed the relationship between respiratory health symptoms and ambient PM concentrations among a predominantly Latino/Hispanic cohort of 722 school age children. Guardians completed a survey of their child's wheeze and respiratory health symptoms over the past 12 months, adapted from the International Study of Asthma and Allergies in Childhood (ISAAC). Exposure to dust storm hours (hourly concentrations >150 μg/m3 for PM10) was estimated using a network of regulatory monitors.

RESULTS

Between 2017 and 2019, children were exposed to 98 to 395 dust event hours annually. We observed disparate effects for dust events and wheeze among children living near the Salton Sea. Every additional 100 dust storm hours per year among children living near the Sea (<11 km) was associated with a 9.5 percentage point increase in wheeze (95% CI: 3.5, 15.4), a 4.6 percentage point increase in bronchitic symptoms (95% CI: 0.18, 10.2) and a 6.7 percentage point increase in sleep disturbance due to wheeze (95% CI: 0.96, 12.4). Similarly, increases in PM10 were also associated with greater reported wheeze and bronchitic symptoms among those living near the Sea, compared to children living ≥11 km from the Sea. There was no association of dust storms or PM10 with wheeze or bronchitic symptoms among the children residing farther from the Sea.

CONCLUSION

We observed stronger adverse impacts of PM10 and dust events on respiratory health among those living closer to the drying Salton Sea, compared to children living farther away. In this community of predominantly low-income residents of color, these impacts raise environmental justice concerns about the effects of the drying Salton Sea on public health.

Do respiratory virus infections modify associations of asthma exacerbation with aeroallergens or fine particulate matter? A time series study in Philadelphia PA

Respiratory virus infections are related to over 80% of childhood asthma exacerbations. They enhance pro-inflammatory mediator release, especially for sensitized individuals exposed to pollens/molds. Using a time-series study design, we investigated possible effect modification by respiratory virus infections of the associations between aeroallergens/PM2.5 and asthma exacerbation rates. Outpatient, emergency department (ED), and inpatient visits for asthma exacerbation among children with asthma (28,540/24,444 [warm/cold season]), as well as viral infection counts were obtained from electronic health records of the Children's Hospital of Philadelphia from 2011 to 2016. Rate ratios (RRs, 90th percentile vs. 0) for late-season grass pollen were 1.00 (0.85-1.17), 1.04 (0.95-1.15), and 1.12 (0.96-1.32), respectively, for respiratory syncytial virus (RSV) counts within each tertile. However, similar trends were not observed for weed pollens/molds or PM2.5. Overall, our study provides little evidence supporting effect modification by respiratory viral infections.

TOLLIP and MUC5B modulate the effect of ambient NO2 on respiratory symptoms in infancy

BACKGROUND

Current knowledge suggests that the gene region containing MUC5B and TOLLIP plays a role in airway defence and airway inflammation, and hence respiratory disease. It is also known that exposure to air pollution increases susceptibility to respiratory disease. We aimed to study whether the effect of air pollutants on the immune response and respiratory symptoms in infants may be modified by polymorphisms in MUC5B and TOLLIP genes.

METHODS

359 healthy term infants from the prospective Basel-Bern Infant Lung Development (BILD) birth cohort were included in the study. The main outcome was the score of weekly assessed respiratory symptoms in the first year of life. Using the candidate gene approach, we selected 10 single nucleotide polymorphisms (SNPs) from the MUC5B and TOLLIP regions. Nitrogen dioxide (NO2) and particulate matter ≤10 μm in aerodynamic diameter (PM10) exposure was estimated on a weekly basis. We used generalised additive mixed models adjusted for known covariates. To validate our results in vitro, cells from a lung epithelial cell line were downregulated in TOLLIP expression and exposed to diesel particulate matter (DPM) and polyinosinic-polycytidylic acid.

RESULTS

Significant interaction was observed between modelled air pollution (weekly NO2 exposure) and 5 SNPs within MUC5B and TOLLIP genes regarding respiratory symptoms as outcome: E.g., infants carrying minor alleles of rs5744034, rs3793965 and rs3750920 (all TOLLIP) had an increased risk of respiratory symptoms with increasing NO2 exposure. In vitro experiments showed that cells downregulated for TOLLIP react differently to environmental pollutant exposure with DPM and viral stimulation.

CONCLUSION

Our findings suggest that the effect of air pollution on respiratory symptoms in infancy may be influenced by the genotype of specific SNPs from the MUC5B and TOLLIP regions. For validation of the findings, we provided in vitro evidence for the interaction of TOLLIP with air pollution.

Children's food allergy: Effects of environmental influences and antibiotic use across critical developmental windows

BACKGROUND

Increasing studies linked outdoor air pollution (OAP), indoor environmental factors (IEFs), and antibiotics use (AU) with the first wave of allergies (i.e., asthma, allergic rhinitis, and eczema), yet the role of their exposures on children's second wave of allergy (i.e., food allergy) are unknown.

OBJECTIVES

To investigate the association between exposure to OAP and IEFs and childhood doctor-diagnosed food allergy (DFA) during the pre-pregnancy, prenatal, early postnatal, and current periods, and to further explore the effect of OAP and IEFs on DFA in children co-exposed to antibiotics.

METHODS

A retrospective cohort study involving 8689 preschoolers was carried out in Changsha, China. Data on the health outcomes, antibiotic use, and home environment of each child were collected through a questionnaire. Temperature and air pollutants data were obtained from 8 and 10 monitoring stations in Changsha, respectively. Exposure levels to temperature and air pollutants at individual home addresses were calculated by the inverse distance weighted (IDW) method. Multiple logistic regression models were employed to assess the associations of childhood DFA with exposure to OAP, IEF, and AU.

RESULTS

Childhood ever doctor-diagnosed food allergy (DFA) was linked to postnatal PM10 exposure with OR (95% CI) of 1.18 (1.03-1.36), especially for CO and O3 exposure during the first year with ORs (95% CI) = 1.08 (1.00-1.16) and 1.07 (1.00-1.14), as well as SO2 exposure during the previous year with OR (95% CI) of 1.13 (1.02-1.25). The role of postnatal air pollution is more important for the risk of egg, milk and other food allergies. Renovation-related IAP (new furniture) and dampness-related indoor allergens exposures throughout all time windows significantly increased the risk of childhood DFA, with ORs ranging from 1.23 (1.03-1.46) to 1.54 (1.29-1.83). Furthermore, smoke-related IAP (environmental tobacco smoke [ETS], parental and grandparental smoking) exposure during pregnancy, first year, and previous year was related to DFA. Additionally, exposure to pet-related indoor allergens (cats) during first year and total plant-related allergens (particularly nonflowering plants) during previous year were associated with DFA. Moreover, exposure to plant-related allergy during first and previous year was specifically associated with milk allergy, while keeping cats during first year increased the risk of fruits/vegetables allergy. Life-time and early-life AU was associated with the increased risk of childhood DFA with ORs (95% CI) = 1.57 (1.32-1.87) and 1.46 (1.27-1.67), including different types food allergies except fruit/vegetable allergy.

CONCLUSIONS

Postnatal OAP, life-time and early-life IEFs and AU exposure played a vital role in the development of DFA, supporting the "fetal origin of childhood FA" hypothesis.

Different Impacts of Traffic-Related Air Pollution on Early-Onset and Late-Onset Asthma

Background

Early-onset asthma (EOA) and late-onset asthma (LOA) are two distinct phenotypes. Air pollution has been associated with an increase in poorer asthma outcomes. The objective of this study was to examine the effects of traffic-related air pollution (TRAP) on asthma outcomes in EOA and LOA patients.

Methods

A cross-sectional study was conducted on 675 asthma patients (LOA: 415) recruited from a major medical center in Taiwan. The land-use regression (LUR) model was used to estimate the level of exposure to PM10, PM2.5, NO2, and O3 on an individual level. We investigated the association between TRAP and asthma outcomes in EOA and LOA patients, stratified by allergic sensitization status, using a regression approach.

Results

An increase in PM10 was associated with younger age of onset, increased asthma duration, and decreased lung function in EOA patients (p<0.05). An increase in PM10 was associated with older age of onset, and decreased asthma duration, eosinophil count, and Asthma Control Test (ACT) score in LOA patients. An increase in PM2.5 was associated with younger age of onset, increased asthma duration, decreased eosinophil count, and lung function in EOA patients (p<0.05). An increase in PM2.5 was associated with decreased lung function and ACT score in LOA patients. An increase in NO2 was associated with increased eosinophil count and decreased lung function in EOA patients (p<0.05). An increase in O3 was associated with decreased lung function in LOA patients (p<0.05). In addition, associations of TRAP with age of onset and eosinophil counts were mainly observed in both EOA and LOA patients with allergic sensitization, and an association with ACT was mainly observed in LOA patients without allergic sensitization.

Conclusion

The impact of TRAP on age of onset, eosinophil count, and lung function in EOA patients, and ACT in LOA patients, was affected by the status of allergic sensitization.

Impact of Climate Change on Indoor Air Quality

Climate change may affect the quality of the indoor environment through heat and mass transfer between indoors and outdoors: first by a direct response to global warming itself and related extreme weather phenomena and second by indirect actions taken to reduce greenhouse gas emissions that can lead to increased concentrations of indoor air contaminants. Therefore, both indoor and outdoor air pollution contribute to poor indoor air quality in this context. Exposures to high concentrations of these pollutants contribute to inflammatory respiratory diseases. Climate change adaptation and mitigation measures could minimize these risks and bring associated health benefits.

Effects of indoor air quality and home environmental characteristics on allergic diseases among preschool children in the Greater Taipei Area

Indoor air quality and home environmental characteristics are potential factors associated with the onset and exacerbation of allergic diseases. Our study examined the effects of these factors on allergic diseases (i.e., asthma, allergic rhinitis, allergic conjunctivitis, and atopic dermatitis) among preschool children. We recruited a total of 120 preschool children from an ongoing birth cohort study in the Greater Taipei Area. A comprehensive environmental evaluation was conducted at each participant's residence and included measurements of indoor and outdoor air pollutants, fungal spores, endotoxins, and house dust mite allergens. A structured questionnaire was used to collect information on the allergic diseases and home environments of participants. Land-use characteristics and points of interest in the surrounding area of each home were analyzed. Other covariates were obtained from the cohort data. Multiple logistic regressions were used to examine the relationships between allergic diseases and covariates. We observed that all mean indoor air pollutant levels were below Taiwan's indoor air quality standards. After adjustment for covariates, the total number of fungal spores and the ozone, Der f 1, and endotoxin levels were significantly associated with increased risks of allergic diseases. Biological contaminants more significantly affected allergic diseases than other pollutants. Moreover, home environmental characteristics (e.g., living near power facilities and gas stations) were associated with an increased risk of allergic diseases. Regular and proper home sanitation is recommended to prevent the accumulation of indoor pollutants, especially biological contaminants. Living away from potential sources of pollution is also crucial for protecting the health of children.

Interaction of high temperature and NO2 exposure on asthma risk: In vivo experimental evidence of inflammation and oxidative stress

Allergic asthma is a complicated respiratory disease with many concerns. Mounting epidemiological evidence linked temperature (T) and NO2 with allergic asthma, yet toxicological studies remain scarce. We conducted an in vivo study to explore toxicological evidence in T-NO2 interaction on allergic asthma, to investigate underlying toxicological mechanisms. 90 male Balb/c mice were randomly and equally divided into 6 groups including saline control, ovalbumin (OVA)-sensitized, OVA + 35 °C, OVA + NO2, OVA + 35 °C + NO2, and OVA + 35 °C + NO2 + capsazepine (CZP), adopting treatment for 38 days. We measured pulmonary functions of inspiratory resistance (Ri), expiratory resistance (Re) and airway compliance (Cldyn), serum protein biomarkers, indexes of pulmonary inflammation, histopathological changes and protective effects of CZP. Airway hyperresponsiveness (AHR) was aggravated by high T (35 °C) and NO2 (5 ppm) co-exposure with a series of aggravating asthmatic symptoms including airway wall thickening, lumen stenosis, goblet cell proliferation, mucus hypersecretion, and subepithelial fibrotic hyperplasia, providing evidence in the toxicological impact of high T-NO2 interaction. The biomarkers of serum immune functions (Total-IgE, OVA-sIgE and IL-4), pro-inflammation (IL-6 and TNF-α), oxidative stress cytokines (8-OHdG, ROS and MDA), airway resistance (Ri and Re), and TRPV1 expression significantly increased, while IFN-γ, GSH and airway compliance (Cldyn) significantly decreased with co-exposure to high T and NO2. We observed that CZP addition significantly ameliorated these toxicological effects and biomarker levels induced by heat-NO2 interaction. Our results suggest a toxicity of heat-NO2 interaction on asthma with clear mechanisms, which can be ameliorated by CZP, indicating that both oxidative stress and TRPV1 expression may be primarily responsible for asthma of heat-NO2-induced toxicity.