Asthma in childhood: a complex, heterogeneous disease

Screening of cytokines-cytokine receptor-associated genes in childhood asthma based on bioinformatics

PURPOSE

To develop efficient diagnostic and treatment approaches, gaining an in-depth knowledge of the molecular mechanisms and potential targets causing childhood asthma is of utmost significance.

METHODS

Childhood asthma datasets were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) between asthmatic child and healthy people were screened by the Limma package. DEGs were subjected to further analyses utilizing GO, KEGG and GSEA analysis. The hub genes associated with childhood asthma were discovered by PPI analysis. The drugs target hub genes were accessed from the DrugBank database. Autodock vina was used to explore the binding ability of targeted drugs to hub genes.

RESULTS

Total 80 DEGs were selected from GSE152004 and GSE65204 datasets. The cytokine-cytokine receptor interaction was the key pathway identified by functional enrichment analysis of shared DEGs. A total of 4 hub genes (CCL26, CXCR6, IL18RAP and CCL20) were identified by the constructed PPI network, among which CXCR6, IL18RAP and CCL20 were significantly decreased in childhood asthma datasets. Whereas, the CCL26 was significantly increased in childhood asthma datasets. Additionally, the extra dataset GSE19187 and GSE240567 were employed for validation. Ultimately, drugs (Cimetidine, Cefaclor and Propofol) that target hub genes have favorable combination ability.

CONCLUSIONS

We have determined that CCL26, CXCR6, IL18RAP and CCL20 might have crucial involvement in the advancement of childhood asthma, thus having the potential to be targeted therapeutically in order to enhance treatment choices for childhood asthma. Statement of Integration, Innovation and Insight: The cytokine-cytokine receptor interaction is a key pathway in the occurrence of childhood asthma. The hub genes (CCL26, CXCR6, IL18RAP and CCL20) affect the development of childhood asthma. The drugs (Cimetidine, Cefaclor and Propofol) that target hub genes have favorable combination ability.

Disadvantage in early-life and persistent asthma in adolescents: a UK cohort study

OBJECTIVE

To determine how early-life risk factors explain socioeconomic inequalities in persistent asthma in adolescence.

METHODS

We did a causal mediation analysis using data from 7487 children and young people in the UK Millennium Cohort Study. Persistent asthma was defined as having a diagnosis reported at any two or more time points at 7, 11 or 14 years. The main exposure was maternal education, a measure of early-life socioeconomic circumstances (SECs), used to calculate the relative index of inequality. We assessed how blocks of perinatal (maternal health behaviours, infant characteristics and duration of breastfeeding, measured at 9 months) and environmental risk factors (family housing conditions; potential exposure to infections through childcare type and sibling number, and neighbourhood characteristics, measured at 3 years) mediated the total effect of childhood SECs on persistent asthma risk, calculating the proportion mediated and natural indirect effect (NIE) via blocks of mediators.

RESULTS

At age 14 the overall prevalence of persistent asthma was 15%. Children of mothers with lower educational qualifications were more likely to have persistent asthma, with a clear social gradient (degree plus: 12.8% vs no qualifications: 20.3%). The NIE gives the effect of SECs acting only via the mediators and shows a 31% increased odds of persistent asthma when SECs are fixed at the highest level, and mediators at the level which would naturally occur at the lowest SECs versus highest SECs (NIE OR 1.31, 95% CI 1.04 to 1.65). Overall, 58.9% (95% CI 52.9 to 63.7) of the total effect (OR 1.70, 95% CI 1.20 to 2.40) of SECs on risk of persistent asthma in adolescence was mediated by perinatal and environmental characteristics.

CONCLUSIONS

Perinatal characteristics and the home environment in early life are more important in explaining socioeconomic inequalities in persistent asthma in British adolescents than more distal environmental exposures outside the home.

Overview of severe asthma, with emphasis on pediatric patients: a review for practitioners

Asthma is the most common life-threatening chronic disease in children. Although guidelines exist for the diagnosis and treatment of asthma, treatment of severe, pediatric asthma remains difficult. Limited studies in the pediatric population on new asthma therapies, complex issues with adolescence and adherence, health disparities, and unequal access to guideline-based care complicate the care of children with severe, persistent asthma. The purpose of this review is to provide an overview of asthma, including asthma subtypes, comorbidities, and risk factors, to discuss diagnostic considerations and pitfalls and existing treatments, and then present existing and emerging therapeutic approaches to asthma management. An improved understanding of asthma heterogeneity, clinical characteristics, inflammatory patterns, and pathobiology can help further guide the management of severe asthma in children. More studies are needed in the pediatric population to understand emerging therapeutics application in children. Effective multimodal strategies tailored to individual characteristics and a commitment to address risk factors, modifiers, and health disparities may help reduce the burden of asthma in the USA.

Early life exposure to phthalates and the development of childhood asthma among Canadian children

BACKGROUND

Studies have demonstrated an association between phthalate exposure and childhood asthma, although results have been inconsistent. No epidemiological studies have examined exposure during the first year of life.

OBJECTIVE

To investigate the association between phthalate exposures in the home environment during the first year of life, and subsequent development of childhood asthma and related symptoms.

METHODS

This study used a case-cohort design including 436 randomly selected children and all additional cases of asthma at 5 years (n_total = 129) and recurrent wheeze between 2 and 5 years (n_total = 332) within the CHILD Cohort Study, a general population Canadian birth cohort of 3455 children. Phthalate exposure was assessed using house dust samples collected during a standardized home visit when children were 3-4 months of age. All children were assessed by specialist clinicians for asthma and allergy at 1, 3 and 5 years. Logistic regression was used to assess the association between exposure to five phthalates and asthma diagnosis at 5 years, and recurrent wheeze between 2 and 5 years, with further stratification by wheeze subtypes (late onset, persistent, transient) based on the timing of onset and persistence of wheeze symptoms.

RESULTS

Di(2-ethylhexyl) phthalate (DEHP) had the highest concentration in dust (median_subcohort = 217 μg/g), followed by benzyl butyl phthalate (BzBP) (20 μg/g). A nearly four-fold increase in risk of developing asthma was associated with the highest concentration quartile of DEHP (OR = 3.92, 95% CI: 1.87-8.24) including a positive dose-response relationship. A two-fold increase in risk of recurrent wheeze was observed across all quartiles compared to the lowest quartile of DEHP concentrations. Compared to other wheeze subtypes, stronger associations for DEHP were observed with the late onset wheezing subtype, while stronger associations for di-iso-butyl phthalate (DiBP) and BzBP were observed with the transient subtype.

DISCUSSION

DEHP exposure at 3-4 months, at concentrations lower than other studies that reported an association, were associated with increased risks of asthma and recurrent wheeze among children at 5 years. These findings suggest the need to assess whether more stringent regulations are required to protect children's health, which can be informed by future work exploring the main sources of DEHP exposure.

Maternal dietary inflammatory potential and quality are associated with offspring asthma risk over 10-year follow-up: the Lifeways Cross-Generation Cohort Study

BACKGROUND

Asthma is the most common childhood chronic health condition. Maternal antenatal diet has been associated with offspring asthma risk, but studies investigating maternal whole diet quality and inflammatory potential with long-term offspring follow-up (>5 y) are rare.

OBJECTIVES

We aimed to elucidate these associations in a prospective cohort study in Ireland.

METHODS

Early pregnancy diets were assessed using a validated FFQ from which energy-adjusted Dietary Inflammatory Index (E-DII) and Healthy Eating Index (HEI)-2015 scores were computed. Doctor-diagnosed offspring asthma status (general practitioner or parent reports) for the first 10 y of life was collected at 3-y, 5-y, and 9-y follow-up. A total of 862 mother-child pairs with information on maternal diet and ≥1 offspring asthma data points were included. The longitudinal associations between maternal E-DII and HEI scores and offspring asthma status were assessed using generalized estimating equations.

RESULTS

Cumulative offspring asthma incidence was 21% over the 10-y period. In the main models, adjusted for maternal lifestyle and sociodemographic factors, a higher E-DII score, indicating a more proinflammatory diet, was associated with higher risk of offspring asthma (OR: 1.35; 95% CI: 1.10, 1.65; per 1-SD score increment), whereas a higher HEI-2015 score, indicating better dietary quality, was associated with lower risk (OR: 0.77; 95% CI: 0.64, 0.93) (both P < 0.01). Results persisted with further adjustment for childhood factors (e.g., breastfeeding, diet, and childcare attendance) and parental asthma history. Similar associations were observed when E-DII and HEI-2015 scores were modeled in quartiles (both P-trend < 0.05). Associations for HEI-2015 were attenuated after adjustment for E-DII, suggesting the importance of anti-inflammatory pathways.

CONCLUSIONS

Our results suggest that a proinflammatory and low-quality diet during pregnancy is associated with a higher risk of offspring asthma. Pending confirmation from other studies, optimizing these aspects of maternal diet can be a promising strategy for reducing childhood asthma risk. This prospective observational study was registered at the ISRCTN Registry as ISRCTN16537904.

Personal and early life factors associated with new-onset asthma, remission, and persistence of asthma in a 2-year follow-up of schoolchildren

OBJECTIVE

The natural course of childhood asthma, after its onset, is characterized by periods of persistence, relapse and remission. To investigate personal and early life factors associated with new-onset asthma, persistence and remission among children.

METHODS

The study was conducted in the province of Saskatchewan, Canada. Children in grades Kindergarten to Grade 8 (ages 5-14 years) participated in a cross-sectional study in 2013. In 2015, we approached those who gave consent in 2013 to be re-contacted, creating a prospective cohort. Data were collected using questionnaires in both years. Participants in 2013 who also had data in 2015 (25%: n = 324/1,348) had their asthma status reclassified and longitudinal descriptors were applied: "no asthma", "new-onset asthma", "persistent" or "remission". Personal and early life factors associations with asthma outcomes in 2015 were evaluated.

RESULTS

Among those without asthma in 2013 (n = 245), the incidence of new-onset asthma in 2015 was 7.2%. Among those with asthma in 2013 (n = 79), 47.1% had remission and 52.9% had persistent asthma in 2015. Parental history of asthma (adjusted odds ratio (aOR): 4.99; 95% confidence interval (CI): 1.88-28.27), early life respiratory infection (aOR: 1.92; 95%CI: 1.47-7.88), early life allergy [aOR: 6.39; 95%CI: 1.34-30.58) and early life infection (aOR: 4.99; 95%CI: 1.19-20.93) were associated with new onset asthma. Similarly, while parental history of asthma (aOR: 1.13; 95%CI: 0.29-4.34), early life respiratory infection (aOR: 2.71; 95%CI: 0.70-10.45), and early life ear infection (aOR: 1.34; 95%CI: 0.36-5.05) were also positively association with persistent asthma, the associations were not statistically significant.

CONCLUSION

Parental history of asthma, early life respiratory infection and allergy might not only influence the onset of childhood asthma but also be associated with asthma persistence.

Patterns of health care use related to respiratory conditions in early life: A birth cohort study with linked administrative data

OBJECTIVES

To identify distinctive patterns of respiratory-related health services use (HSU) between birth and 3 years of age, and to examine associated symptom and risk profiles.

METHODS

This study included 729 mother and child pairs enrolled in the Toronto site of the Canadian Healthy Infant Longitudinal Development study in 2009-2012; they were linked to Ontario health administrative databases (2009-2016). A model-based cluster analysis was performed to identify distinct groups of children who followed a similar pattern of respiratory-related HSU between birth and 3 years of age, regarding hospitalization, emergency department (ED) and physician office visits for respiratory conditions and total health care costs (2016 Canadian dollars).

RESULTS

The majority (estimated cluster weight = 0.905) showed a pattern of low and stable respiratory care use (low HSU) while the remainder (weight = 0.095) showed a pattern of high use (high HSU). From 0 to 3 years of age, the low- and high-HSU groups differed in mean trajectories of total health care costs ($783 per 6 months decreased to $114, vs $1796 to $177, respectively). Compared to low-HSU, the high-HSU group was associated with a constant risk of hospitalizations, early high ED utilization and physician visits for respiratory problems. The two groups differed significantly in the timing of wheezing (late onset in low-HSU vs early in high-HSU) and future total costs (stable vs increased).

CONCLUSIONS

One in ten children had high respiratory care use in early life. Such information can help identify high-risk young children in a large population, monitor their long-term health, and inform resource allocation.

Anti-inflammatory Potentials of Excretory/Secretory (ES) and Somatic Products of Marshallagia marshalli on Allergic Airway Inflammation in BALB/c Mice

BACKGROUND

Inverse relationship between helminths infection and immune-mediated diseases has inspired researchers to investigate therapeutic potential of helminths in allergic asthma. Helminth unique ability to induce immunoregulatory responses has already been documented in several experimental studies. This study was designed to investigate whether excretory/secretory (ES) and somatic products of Marshallagia marshalli modulate the development of ovalbumin-induced airway inflammation in a mouse model.

METHODS

This study was carried out at the laboratories of Immunology and Parasitology of Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran during spring and summer 2015. Allergic airway inflammation was induced in mice by intraperitoneal (IP) injection with ovalbumin (OVA). The effects of ES and somatic products of M. marshalli were analyzed by inflammatory cell infiltration in bronchoalveolar lavage fluid (BALF), pathological changes and IgE response.

RESULTS

Treatment with ES and somatic products of M. marshalli decreased cellular infiltration into BALF when they were administered during sensitization with allergen. Pathological changes were decreased in helminth-treated group, as demonstrated by reduced inflammatory cell infiltration, goblet cell hyperplasia, epithelial lesion and smooth muscle hypertrophy. However, no significant differences were observed in IgE serum levels, cytokines and eosinophil counts between different groups.

CONCLUSION

This study provides new insights into anti-inflammatory effects of ES and somatic products of M. marshalli, during the development of non-eosinophilic model of asthma. Further study is necessary to characterize immunomodulatory molecules derived from M. marshalli as a candidate for the treatment of airway inflammation.

Early life environmental predictors of asthma age-of-onset

Prevention strategies that delay the onset of asthma may improve clinical outcomes. To identify early life environmental exposures associated with asthma age-of-onset and potential genetic modifiers of these exposures, we studied 1085 subjects with physician-diagnosed asthma and disease onset at or after age two. Subjects reported retrospectively on their exposure to 17 environmental factors before the age of two. The presence of individual or combinations of these early life exposures was then tested for association with variation in asthma age-of-onset. For exposures significantly associated with age-of-onset, we tested if 26 single nucleotide polymorphisms (SNP) with an established association with allergic disease significantly modified the effect of the exposure. Five environmental exposures were significantly associated with variation in asthma age-of-onset after correction for multiple testing: carpet at home (P = 6 × 10⁻⁵), a serious chest illness (P = 10⁻⁴), father a cigarette smoker (P = 6 × 10⁻⁴) and direct exposure to father's smoking (P = 3 × 10⁻⁴). Individuals with early childhood asthma onset, between the ages of two and six, were 1.4-fold (CI 1.1–1.9) more likely to report having lived in a house with carpet and 2.1-fold (CI 1.3–3.5) more likely to report suffering a serious chest illness before the age of two, than asthmatics with later disease onset. We further found these individual risks to increase to 3.2-fold (CI 1.7–6.0) if carpet exposure and suffering a serious chest illness co-occurred before age two. Paternal smoking exposures were less likely to be reported by asthmatics with early when compared to later disease onset (OR 0.5, CI 0.3–0.7). There were no significant SNP interactions with these environmental exposures after correction for multiple testing. Our results suggest that disease onset in individuals at a high-risk of developing asthma can potentially be delayed by avoiding exposure to carpet at home and preventing serious chest illnesses during the first 2 years of life.

Indoor air pollution and respiratory health of children in the developing world

Indoor air pollution (IAP) is a key contributor to the global burden of disease mainly in developing countries. The use of solid fuel for cooking and heating is the main source of IAP in developing countries, accounting for an estimated 3.5 million deaths and 4.5% of Disability-Adjusted Life Years in 2010. Other sources of IAP include indoor smoking, infiltration of pollutants from outdoor sources and substances emitted from an array of human utilities and biological materials. Children are among the most vulnerable groups for adverse effects of IAP. The respiratory system is a primary target of air pollutants resulting in a wide range of acute and chronic effects. The spectrum of respiratory adverse effects ranges from mild subclinical changes and mild symptoms to life threatening conditions and even death. However, IAP is a modifiable risk factor having potential mitigating interventions. Possible interventions range from simple behavior change to structural changes and from shifting of unclean cooking fuel to clean cooking fuel. Shifting from use of solid fuel to clean fuel invariably reduces household air pollution in developing countries, but such a change is challenging. This review aims to summarize the available information on IAP exposure during childhood and its effects on respiratory health in developing countries. It specifically discusses the common sources of IAP, susceptibility of children to air pollution, mechanisms of action, common respiratory conditions, preventive and mitigating strategies.

Patterns of sensitisation to common food and inhalant allergens and allergic symptoms in pre-school children

AIM

Sensitisation to allergens and allergy symptoms depends on age, but this relationship is poorly understood. We therefore investigated the effect of age on allergen sensitisation and allergy symptoms in pre-school children.

METHODS

A cross-sectional study was conducted on 629 Korean children (age 3 to 6 years). Current allergic symptoms were assessed by the Korean version of the International Study of Asthma and Allergies in Childhood questionnaire that was adapted for pre-school children. Sensitisation to five airborne and three food allergens was evaluated by a skin prick test. χ(2) test was used to analyse differences in age trend. Multiple logistic regression analysis was performed to obtain the adjusted odds ratios (aOR) for allergic disease.

RESULTS

As age increased, the prevalence of current rhinitis (P < 0.001), the sensitisation to pollen allergens (P < 0.001) and polysensitised children (P = 0.002) increased, but the prevalence of current asthma (P = 0.010) and the sensitisation to food allergens (P = 0.009) decreased. There was no effect of age on the prevalence of current eczema (P = 0.685), monosensitised children (P = 0.282) and atopy (P = 0.160). The agreement between sensitisation to dust mites and atopy increased with age, and was 93% at age 6 years (P = 0.05). The polysensitisation (aOR = 3.0 (95% CI, 1.4-5.0), P < 0.005) and the presence of eczema in the first 2 years of life (aOR = 4.1 (95% CI, 2.2-7.6), P < 0.001) were significant independent risk factors for current rhinoconjunctivitis.

CONCLUSION

The type and number of allergen sensitisations and allergic symptoms changed from age 3 to 6 years. Careful follow-up of changes in sensitisation patterns may provide a better understanding of the pathogenesis of the allergic march.

Use of impulse oscillometry system in assessment of asthma severity for preschool children

OBJECTIVE

The National Asthma Education and Prevention Program/Expert Panel Report (NAEPP/EPR)-3 Guidelines for asthma treatment categorize asthma severity based on impairment and risks and on medications administered. The objective of this study was to determine whether impulse oscillometry system (IOS) measures in preschool children are consistent with asthma severity as defined by NAEPP/EPR-3 Guidelines.

METHODS

Asthma severity of the 162 subjects (aged 2-5 years) was classified by impairment and risks for exacerbations requiring oral systemic corticosteroids, by medication usage, and by combination classification (higher severity of impairment and risks or medication usage). An experienced pediatrician determined the appropriate medications for each child and parents completed structured questionnaires regarding day and night symptoms and interference with normal activity over the preceding 4 weeks. All children were tested by IOS.

RESULTS

The mean age was 3.7 ± 0.9 years and 91 (56%) of the total patients were males. When asthma severity was based on (1) impairment and risks and (2) medication usage, asthma was "intermittent" in 17.9% and 11.1% of the total patients, "mild persistent" in 42.0% and 50.6% of total patients, and "moderate-severe persistent" in 40.1% and 38.3% of total patients, respectively. The agreement between severity based on impairment and risks and medication usage was not significant. Xrs(5) z-scores differed between intermittent asthma and mild/moderate-severe persistent asthma, as determined by medication usage and combination classification, but not by impairment and risks. As asthma severity (assessed by medication usage) increased, the duration of asthma increased.

CONCLUSIONS

Xrs(5) can be used to discriminate intermittent and persistent asthma in preschool children. Further studies with larger sample sizes are warranted to confirm this finding and to determine the underlying mechanism.

Respiratory health status of children from two different air pollution exposure settings of Sri Lanka: a cross-sectional study

BACKGROUND

Health effects due to air pollution is becoming a major public health problem with growing traffic congestion and establishment of small- to medium-scale industries with poor emission controls in urban cities of Sri Lanka.

METHODS

Respiratory health status of 7- to 10-year-old children in two settings (urban and semi-urban) was assessed using standard questionnaires. Information on socio-demographic characteristics and potential determinants of both outdoor and indoor air pollutants exposure levels were also obtained. The respiratory health status of children in the two settings was compared.

RESULTS

We found that children from the urban setting had a significantly higher prevalence of wheezing within the last 12 months as compared to children from the semi-urban setting (adjusted OR = 2.02; 95% CI = 1.13-3.59). Indoor cooking with unclean fuels was a risk factor for wheezing independent of the area of residence (adjusted OR = 1.57; 95% CI = 1.01-2.46).

CONCLUSIONS

Poor indoor air quality was a major determinant of wheezing for the overall study group. Children from urban areas of Sri Lanka have poorer respiratory health status as compared to children from semi-urban areas. Besides poor outdoor air quality, this difference may also be due to other unexplored factors which may differ between urban and semi-urban areas in Sri Lanka.

Microbes and asthma: the missing cellular and molecular links

PURPOSE OF REVIEW

In this review, we describe the 'state-of-the-art' in our knowledge of asthma and what gaps exist, which can be exploited in the future for effective translation of our knowledge from the bench or population studies to diagnosis and therapy.

RECENT FINDINGS

The advent of microbiome research has expanded the potential role of microbes in asthma. There has been a significant increase in our understanding of the pathologic, genetic, cellular and molecular mechanisms of asthma. Nonetheless, the contribution of microbes to the genesis, exacerbation and treatment of asthma are poorly understood.

SUMMARY

Asthma is a complex chronic disease of the lung whose incidence is growing at all ages despite the progress that has been made in the areas of diagnosis and treatment of asthma. The complexity is partly due to the environmental insults such as allergens and microbial infections that play differential roles in the pathogenesis of childhood vis-à-vis elderly asthma. Microbes may play important roles in the exacerbation of asthma and hence in the comorbidities due to asthma, and also in the causation of asthma.

Carotenoid intake and asthma prevalence in Thai children

Several antioxidant nutrients have been described to inversely correlate with asthma. In order to quantify the intake of these substances, it is possible to measure skin levels by Raman spectroscopy, a novel non-invasive technique that can also be used in children. This cross-sectional school-based study involved 423 children from a rural area of Thailand. Asthmatic children were diagnosed according to a Health Interview for Asthma Control questionnaire. Skin carotenoid levels were measured with Raman spectroscopy. Demographic data were obtained by directly interviewing children and their parents, whereas anthropometric parameters were measured by trained staff. Intake of carotenoids, vitamin A and C were evaluated by a food frequency questionnaire. Overall incidence of asthma in Thai schoolchildren (aged 3.5-17.8 years) was 17.3%. There was no significant difference in dietary intake of carotenoids and vitamin A and C, and skin carotenoid level between asthmatic and non-asthmatic children. Skin carotenoid level significantly correlated with all carotenoids and vitamin A intake (P<0.05). Carotenoids and vitamin A and C intakes, and skin carotenoid levels were not associated with the risk of asthma in Thai children. Skin carotenoids correlated with all carotenoids and vitamin A intake in mild to moderate degrees. Raman spectroscopy was confirmed to be a useful tool to determine antioxidant skin levels.