Prenatal particulate matter affects new asthma via airway hyperresponsiveness in schoolchildren

Insights from the COCOA birth cohort: The origins of childhood allergic diseases and future perspectives

The ongoing COhort for Childhood Origin of Asthma and allergic diseases (COCOA) study is a prospective birth cohort investigating the origin and natural courses of childhood allergic diseases, including atopic dermatitis, food allergy, allergic rhinitis and asthma, with long-term prognosis. Initiated under the premise that allergic diseases result from a complex interplay of immune development alterations, environmental exposures, and host susceptibility, the COCOA study explores these dynamic interactions during prenatal and postnatal periods, framed within the hygiene and microbial hypotheses alongside the developmental origins of health and disease (DOHaD) hypothesis. The scope of the COCOA study extends to genetic predispositions, indoor and outdoor environmental variables affecting mothers and their offsprings such as outdoor and indoor air pollution, psychological factors, diets, and the microbiomes of skin, gut, and airway. We have embarked on in-depth investigations of diverse risk factors and the pathophysiological underpinnings of allergic diseases. By employing multi-omics approaches-proteomics, transcriptomics, and metabolomics-we gain deeper insights into the distinct pathophysiological processes across various endotypes of childhood allergic diseases, incorporating the exposome using extensive resources within the COCOA study. Integration with large-scale datasets, such as national health insurance records, enhances robustness and mitigates potential limitations inherent to birth cohort studies. As part of global networks focused on childhood allergic diseases, the COCOA study fosters collaborative research across multiple cohorts. The findings from the COCOA study are instrumental in informing precision medicine strategies for childhood allergic diseases, underpinning the establishment of disease trajectories.

Size-segregated particle number concentrations and outpatient-department visits for pediatric respiratory diseases in Shanghai, China

BACKGROUND

Few studies have simultaneously explored which size of particles has the greatest impact on the risk for pediatric asthma, bronchitis and upper respiratory tract infections (URTIs).

OBJECTIVES

To investigate the short-term association between size-segregated particle number concentrations (PNCs) and outpatient-department visits (ODVs) for major pediatric respiratory diseases.

METHODS

Daily counts of pediatric ODVs for asthma, bronchitis and URTIs were obtained from 66 hospitals in Shanghai, China, from 2016 to 2018. Pollutant effects were estimated using Poisson generalized additive models combined with polynomial distributed lag models. We also fitted co-pollutant cumulative effects models included six criteria air pollutants and conducted stratifying analyses by gender, age, season and geographic distances.

RESULTS

We identified a total of 430,103 patients with asthma, 1,547,013 patients with bronchitis, and 2,155,738 patients with URTIs from the hospitals. Effect estimates increased with decreasing particle size. Ultrafine particle (UFP) and PNCs of 0.10-0.40 µm particles (PNC_0.10-0.40) were associated with increased ODVs for asthma, bronchitis and URTIs at cumulative lags up to 3d. Associations tended to appear stable after adjusting for criteria air pollutants. At the cumulative lag 0-2d, each interquartile range increase in UFP was associated with increased ODVs due to asthma (relative risk 1.21, 95% CI: 1.07, 1.38), bronchitis (1.20, 95% CI: 1.07, 1.34) and URTI (1.17, 95% CI: 1.06, 1.30), whereas the associations for PNC_0.10-0.40 remained significant but attenuated in magnitude.

CONCLUSIONS

UFP may be a leading contributor to the adverse respiratory effects of particulate air pollution and the effects increased with decreasing particle size.

The effect window for sulfur dioxide exposure in pregnancy on childhood asthma and wheezing: A case-control study

BACKGROUND

The relationship between prenatal exposure to sulfur dioxide (SO₂) and childhood wheezing and asthma is unclear.

OBJECTIVE

To explore the association between prenatal exposure to SO₂ and childhood wheeze and asthma. To investigate the effects for the exposure during different pregnancy trimesters.

METHODS

We conducted a cross-sectional study firstly in Jinan City to get the prevalence of wheeze and asthma on children aged 18 months to 3 years. And then, we designed a case-control study based on population to evaluate the association between prenatal SO₂ exposure and childhood asthma and wheezing. Based on the starting and ending date of pregnancy and specific residential addresses, the individual concentrations of SO₂ during pregnancy was evaluated using an inverse distance weighted model.

RESULTS

The prevalence of wheeze and asthma on children aged 18 months to 3 years was 2.07% in our cross-sectional study. 236 cases and 1445 controls were available for exposure estimates. The OR (95% CI) of 1.296 (1.130-1.491) was significant after adjusting for the covariates. In the first and third trimesters, the effects were enhanced to 1.602 (1.275-2.022) and 1.448 (1.179-1.783) in the multi-pollutant model with adjusting the effects of other trimesters. Coincidentally, the SO₂ exposure level of the case in the first trimester was higher than that in the second and third trimesters (P < 0.001); however, there was no significant difference in exposure levels of the case between the second and third trimesters of pregnancy (P = 0.381).

CONCLUSION

Prenatal exposure to higher concentration of SO₂ could increase the risk of asthma and wheezing in younger children. The first trimester might be just the window for the toxic effect, while the third trimester was the sensitive window for the effect of SO₂ exposure during pregnancy on childhood asthma.

Risk factors of asthma in the Asian population: a systematic review and meta-analysis

Background and objective

An increasing trend of asthma prevalence was observed in Asia; however, contributions of environmental and host-related risk factors to the development of this disease remain uncertain. This study aimed to perform a systematic review and meta-analysis for asthma-associated risk factors reported in Asia.

Methods

We systematically searched three public databases (Web of Science, PubMed, and Scopus) in Feb 2021. We only included articles that reported environmental and host-related risk factors associated with asthma in the Asian population. Random-effect meta-analyses were conducted for frequently reported asthma-associated risk factors to provide an overall risk estimate of asthma development.

Results

Of 4030 records obtained from public databases, 289 articles were selected for review. The most frequently reported asthma-associated risk factor was the family history of allergy-related conditions. The random-effect asthma risk estimates (pooled odds ratio, OR) were 4.66 (95% confidence interval (CI): 3.73–5.82) for the family history of asthma, 3.50 (95% CI: 2.62–4.67) for the family history of atopy, 3.57 (95% CI: 3.03–4.22) for the family history of any allergic diseases, 1.96 (95% CI: 1.47–2.61) for the family history of allergic rhinitis, and 2.75 (95% CI: 1.12–6.76) for the family history of atopic dermatitis. For housing-related factors, including the presence of mold, mold spots, mold odor, cockroach, water damage, and incense burning, the random-effect pooled OR ranged from 1.43 to 1.73. Other risk factors with significant pooled OR for asthma development included male gender (1.30, 95% CI: 1.23–1.38), cigarette smoke exposure (1.44, 95% CI: 1.30–1.60), cigarette smoking (1.66, 95% CI: 1.44–1.90), body mass index (BMI)–related parameters (pooled OR ranged from 1.06 to 2.02), various types of air pollution (NO₂, PM10, and O₃; pooled OR ranged from 1.03 to 1.22), and pre- and perinatal factors (low birth weight, preterm birth, and cesarean section; pooled OR ranged from 1.14 to 1.32).

Conclusions

The family history of asthma was the most frequently reported risk factor for asthma development in Asia with the highest risk estimate for asthma development. This suggests a major role of the genetic component in asthma pathogenesis. Further study on asthma genetics is required to improve the current understanding of asthma etiology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40101-021-00273-x.

Prenatal and Perinatal Environmental Influences Shaping the Neonatal Immune System: A Focus on Asthma and Allergy Origins

It is suggested that programming of the immune system starts before birth and is shaped by environmental influences acting during critical windows of susceptibility for human development. Prenatal and perinatal exposure to physiological, biological, physical, or chemical factors can trigger permanent, irreversible changes to the developing immune system, which may be reflected in cord blood of neonates. The aim of this narrative review is to summarize the evidence on the role of the prenatal and perinatal environment, including season of birth, mode of delivery, exposure to common allergens, a farming environment, pet ownership, and exposure to tobacco smoking and pollutants, in shaping the immune cell populations and cytokines at birth in humans. We also discuss how reported disruptions in the immune system at birth might contribute to the development of asthma and related allergic manifestations later in life.

Asthma and air pollution: recent insights in pathogenesis and clinical implications

PURPOSE OF REVIEW

Air pollution has adverse effects on the onset and morbidity of respiratory diseases, including asthma. In this review, we discuss recent insights into the effects of air pollution on the incidence and exacerbation of asthma. We focus on epidemiological studies that describe the association between air pollution exposure and development, mortality, persistence and exacerbations of asthma among different age groups. Moreover, we also provide an update on translational studies describing the mechanisms behind this association.

RECENT FINDINGS

Mechanisms linking air pollutants such as particulate matter, nitrogen dioxide (NO2) and ozone to the development and exacerbation of asthma include the induction of both eosinophilic and neutrophilic inflammation driven by stimulation of airway epithelium and increase of pro-inflammatory cytokine production, oxidative stress and DNA methylation changes. Although exposure during foetal development is often reported as a crucial timeframe, exposure to air pollution is detrimental in people of all ages, thus influencing asthma onset as well as increase in asthma prevalence, mortality, persistence and exacerbation.

SUMMARY

In conclusion, this review highlights the importance of reducing air pollution levels to avert the progressive increase in asthma incidence and morbidity.

Prenatal and early life exposure to particulate matter, environmental tobacco smoke and respiratory symptoms in Mexican children

BACKGROUND

Exposure to particulate matter <2.5 μm in diameter (PM2.5) and environmental tobacco smoke (ETS) are associated with respiratory morbidity starting in utero. However, their potential synergistic effects have not been completely elucidated. Here, we examined the joint effects of prenatal and early life PM2.5 and prenatal ETS exposure on respiratory outcomes in children.

MATERIAL AND METHODS

We studied 536 mother-child dyads in the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) study in Mexico City. Exposure to PM2.5 was estimated using residence in pregnancy and child's first year of life with a satellite-based spatio-temporal model. ETS exposure was assessed by caregiver's report of any smoker in the household during the second or third trimester. Outcomes included report of ever wheeze and wheeze in the past 12 months (current wheeze) assessed when children were 6-8 years old considered in separate models. Associations were modeled using distributed lag models (DLM) with daily PM2.5 averages for pregnancy and the first year of life, adjusting for child's sex, birth weight z-score, mother's age and education at enrollment, maternal asthma, season of conception and stratified by prenatal ETS exposure (yes/no).

RESULTS

We identified a sensitive window from gestational week 14 through postnatal week 18 during which PM2.5 was associated with higher risk of ever wheeze at age 6-8 years. We also observed a critical window of PM2.5 exposure between postnatal weeks 6-39 and higher risk of current wheeze. We found significant associations between higher prenatal and early life PM2.5 exposure and higher cumulative risk ratios of ever wheeze (RR:3.76, 95%CI [1.41, 10.0] per 5 μg/m3) and current wheeze in the past year (RR:7.91, 95%CI [1.5, 41.6] per 5 μg/m3) only among children born to mothers exposed to ETS in pregnancy when compared to mothers who were not exposed.

CONCLUSIONS

Exposure to prenatal ETS modified the association between prenatal and early life PM2.5 exposure and respiratory outcomes at age 6-8 years. It is important to consider concurrent chemical exposures to more comprehensively characterize children's environmental risk. Interventions aimed at decreasing passive smoking might mitigate the effects of ambient air pollution.

Advances and recent developments in asthma in 2020

In this review, we discuss recent publications on asthma and review the studies that have reported on the different aspects of the prevalence, risk factors and prevention, mechanisms, diagnosis, and treatment of asthma. Many risk and protective factors and molecular mechanisms are involved in the development of asthma. Emerging concepts and challenges in implementing the exposome paradigm and its application in allergic diseases and asthma are reviewed, including genetic and epigenetic factors, microbial dysbiosis, and environmental exposure, particularly to indoor and outdoor substances. The most relevant experimental studies further advancing the understanding of molecular and immune mechanisms with potential new targets for the development of therapeutics are discussed. A reliable diagnosis of asthma, disease endotyping, and monitoring its severity are of great importance in the management of asthma. Correct evaluation and management of asthma comorbidity/multimorbidity, including interaction with asthma phenotypes and its value for the precision medicine approach and validation of predictive biomarkers, are further detailed. Novel approaches and strategies in asthma treatment linked to mechanisms and endotypes of asthma, particularly biologicals, are critically appraised. Finally, due to the recent pandemics and its impact on patient management, we discuss the challenges, relationships, and molecular mechanisms between asthma, allergies, SARS-CoV-2, and COVID-19.

Furry pet-related wheeze and rhinitis in pre-school children across China: Associations with early life dampness and mould, furry pet keeping, outdoor temperature, PM10 and PM2.5

BACKGROUND

Few Chinese population studies exist on early life risk factors for furry pet allergy.

OBJECTIVES

We studied childhood respiratory symptoms when in contact with furry pets in relation to early life exposure. Moreover, we studied similar environmental associations for rhinitis not related to furry pets.

METHODS

Children aged 3-6 y from day care centres in seven Chinese cities participated (N = 39,782). Parents answered a questionnaire on home environment and children's health, including rhinoconjunctivitis and wheeze when in contact with furry pets, and diagnosed rhinitis. Prenatal and postnatal outdoor temperature, PM_2.5, PM₁₀, and NO₂ were calculated using data from monitoring stations. Associations were estimated by multilevel logistic regression.

RESULTS

Totally 2% had cats, 4% dogs, and 3.2% had rhinoconjunctivitis or wheeze when in contact with furry pets (FP symptoms). Moreover, 1.1% had furry pet related diagnosed rhinitis and 7.5% had diagnosed rhinitis not related to furry pets (other diagnosed rhinitis). Prenatal PM_2.5 and PM₁₀, especially in second trimester, and a colder climate were risk factors for FP symptoms. ETS, dampness and mould, condensation on windows in wintertime, and cats and dog keeping were associated with FP symptoms. Breast feeding and frequent window opening were protective. Similar indoor associations were found for furry pet related diagnosed rhinitis. ETS, dampness and mould, window condensation, urbanization and mechanical exhaust ventilation were risk factors for other diagnosed rhinitis. Cooking with an electric stove and early life exposure to animals (cats, dogs, farm environment during pregnancy) were protective for diagnosed rhinitis not related to furry pets.

CONCLUSIONS

Prenatal outdoor PM₁₀ and PM_2.5 can be risk factors for symptoms suggestive of furry pet allergy. Early life dampness and mould can be risk factors for rhinitis related and not related to furry pets. Exposure to animals (cats, dogs, farm environment) may reduce diagnosed rhinitis not related to furry pets.

Early-life exposure to air pollution and childhood allergic diseases: an update on the link and its implications

INTRODUCTION

Although mounting evidence has linked environmental factors with childhood allergies, some specific key issues still remain unclear: what is the main environmental factor? what is the critical timing window? And whether these contribute to the development of disease?

AREAS COVERED

This selective review summarizes recent epidemiological studies on the association between early-life exposure to indoor/outdoor air pollution and childhood allergic diseases. A literature search was conducted in the PubMed and Web of Science for peer-reviewed articles published until April 2020. Exposure to the traffic-related air pollutant, NO₂, exposure during pregnancy and early postnatal periods is found to be associated with childhood allergies, and exposure during different trimesters causes different allergic diseases. However, exposure to classical air pollutants (PM₁₀ and SO₂) also contributes to childhood allergy in developing countries. In addition, early-life exposure to indoor renovation and mold/dampness significantly increases the risk of allergy in children. A synergistic effect between indoor and outdoor air pollution is found in the development of allergic diseases.

EXPERT OPINION

Early-life exposure to outdoor air pollution and indoor environmental factors plays an important role in the development of childhood allergic diseases, and the synergy between indoor and outdoor exposures increases allergy risk. The available findings support the hypothesis of the 'fetal origins of childhood allergy,' with new implications for the effective control and early prevention of childhood allergies.

A Novel Link between Early Life Allergen Exposure and Neuroimmune Development in Children

Purpose

As COVID-19 unprecedented situation significantly increased the time families spend indoors, the awareness of unhealthy living conditions negatively impacting immune system and early neurodevelopment of children is of crucial importance.

Methods

We retrospectively reviewed unrelated cases of the children with confirmed multiple indoor allergen sensitization due to prolonged exposure to unhealthy indoor environment with infestation and water damage, who, in addition to multiple health problems related to allergy and asthma, also developed neuroimmune complications and growth delay.

Results

Documented early in life atypical neurologic and behavioral changes were common in all cases. Clinical analysis did not establish other causative reason aside from prenatal and early life exposure to unhealthy living conditions. Alternaria Alternara and Penicillium/Aspergillus molds were found in all homes and sensitization was confirmed in all cases. Significant similarities in the symptoms recorded in all three families led us to a hypothesis that, likely, a significant level of the immune response to external immunogenic pathological stimulus such as mold spore protein, mycotoxin protein, dust mite protein, decay-related volatile particles (VOC) skewed a balance of the neuroimmune interactions, and further affected neuronal network establishment. As all children exhibited significant spectrum of the systemic inflammatory conditions early in life, coupled with inability to follow normal neurodevelopment, we hypothesize that an overwhelming activation of the aggressive immune mechanisms by the epigenetic factors led to glia activation, cytokine storm and break of tolerance.

Conclusions

We hypothesize that developing immune system exhibited aggressive responses due to environmental danger signals, subsequently TH-1 or TH-2 switch enables multiple clinical syndromes development with atypical presentation due to the described novel mechanism. An increased due to the COVID-19 lock-down may increase an amount of exposure of vulnerable people to indoor biological particles and volatile organic compounds present in unhealthy buildings. It is of crucial importance to identify and remediate indoor exposure factors that can decrease immune protection, especially against infectious pathogens such as novel coronavirus.

The Role and Potential Pathogenic Mechanism of Particulate Matter in Childhood Asthma: A Review and Perspective

Asthma, the most common chronic respiratory disease in children, affects numerous people worldwide. Accumulating evidence suggests that exposure to high levels of particulate matter (PM), either acutely or chronically, is associated with the exacerbation and incidence of pediatric asthma. However, the detailed pathogenic mechanisms by which PM contributes to the incidence of asthma remain largely unknown. In this short review, we summarize studies of relationships between PM and pediatric asthma and recent advances on the fundamental mechanisms of PM-related asthma, with emphases on cell death regulation and immune system responses. We further discuss the inadequacy of current studies and give a perspective on the prevention strategies for pediatric asthma.

Evidence for the critical role of the PI3K signaling pathway in particulate matter-induced dysregulation of the inflammatory mediators COX-2/PGE2 and the associated epithelial barrier protein Filaggrin in the bronchial epithelium

Particulate matter (PM) is an environmental pollutant closely associated with human airway inflammation. However, the molecular mechanisms of PM-related airway inflammation remains to be fully elucidated. It is known that COX-2/PGE₂ play key roles in the pathogenesis of airway inflammation. Filaggrin is a transmembrane protein contributing to tight junction barrier function. As such, Filaggrin prevents leakage of transported solutes and is therefore necessary for the maintenance of epithelial integrity. The objective of the present study was to investigate the regulatory mechanisms of COX-2/PGE₂ and Filaggrin upon PM exposure both in vivo and in vitro. C57BL/6 mice received intratracheal instillation of PM for two consecutive days. In parallel, human bronchial epithelial cells (HBECs) were exposed to PM for 24 h. PM exposure resulted in airway inflammation together with upregulation of COX-2/PGE₂ and downregulation of Filaggrin in mouse lungs. Corresponding dysregulation of COX-2/PGE₂ and Filaggrin was also observed in HBECs subjected to PM. PM exposure led to the phosphorylation of ERK, JNK, and PI3K signaling pathways in a time-dependent manner, while blockade of PI3K with the specific molecular inhibitor LY294002 partially reversed the dysregulation of COX-2/PGE₂ and Filaggrin. Moreover, pretreatment of HBECs with NS398, a specific molecular inhibitor of COX-2, and AH6809, a downstream PGE₂ receptor inhibitor, reversed the downregulation of Filaggrin upon PM exposure. Taken together, these data demonstrated that the PI3K signaling pathway upregulated COX-2 as well as PGE₂ and acted as a pivotal mediator in the downregulation of Filaggrin.

Early-life exposure to humidifier disinfectant determines the prognosis of lung function in children

BACKGROUND

Use of humidifier disinfectants (HD) at home leads to chemical airborne exposure, causing HD associated lung injury (HDLI) with high mortality. However, the lung function in children diagnosed with HDLI is not well studied. We investigated the effect of HD exposure on lung function, prognosis, and exposure characteristics associated with the lung function phenotype in children.

METHODS

Eighty-one children diagnosed with HDLI in a nationwide cohort were tested for spirometry and diffusing capacity of the lung for carbon monoxide (DLco) from July 2013 and followed up with at five time points over 2 years. The results were compared with 122 children without HD exposure as controls. Home investigation and questionnaire analysis were conducted to assess HD inhalation exposure.

RESULTS

HDLI survivor's mean percent of predicted forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC), and corrected DLco were significantly lower compared with the control group. On longitudinal assessment, FVC was within the normal range, but flattened, and spirometry showed a predominantly restrictive pattern. Corrected DLco did not normalize above 80% despite increasing age. The persistently low phenotype of lung function was associated with initial exposure age, especially less than 12 months of age. Higher density HD exposure during sleep and close distance between the bed and the humidifier were significantly associated with persistently low corrected DLco.

CONCLUSIONS

HD exposure affects prolonged decrement in lung function, especially DLco, particularly among children who are exposed within the first year of life. These results suggested that early-life HD exposure determines long-term prognosis of lung function in children.