Current and future management of the young child with early onset wheezing

The role of atopy in asthma development and persistence

PURPOSE OF REVIEW

Asthma is the most common chronic disease in pediatric age. Childhood-onset asthma, as opposed to adult-onset asthma, is typically characterized by a personal and often a family history of atopy and related markers of type 2-mediated inflammation. However, the interplay between atopy and asthma development is more complex than a linear dose-response relationship.

RECENT FINDINGS

Family and personal history of atopic diseases have been confirmed as major risk factors for asthma occurrence and persistence in children. Early life and multiple sensitizations to aeroallergens significantly increase the risk of asthma development in school age. Early life lower respiratory tract viral infections, especially caused by rhinovirus, also increase the susceptibility to atopic asthma in childhood. Human rhinovirus type C receptor CDHR3 polymorphisms have been shown to affect receptor epithelial expression, activation, and asthma development and exacerbation severity in children. Atopic sensitization and respiratory viral infections can synergistically enhance the susceptibility to asthma through multiple mechanisms, including the IgE-mediated inhibition of innate antiviral responses to rhinovirus. Emerging evidence shows that several nonatopic factors are also involved in the asthma pathogenesis in genetically predisposed individuals, including early life exposure to environmental factors, and lung and gut microbiome composition.

SUMMARY

The current review outlines recent data on the complex role of atopy in asthma pathogenesis and persistence, and addresses new research topics such as the role of epigenetics and the lung microbiome.

Identification of bronchiolitis profiles in Italian children through the application of latent class analysis

BACKGROUND

Bronchiolitis is the primary infection of the lower respiratory tract in children under 2 years of age. Although it is generally considered a single nosological entity, recent studies suggested remarkable clinical heterogeneity. To date, no studies have identified classes of children with bronchiolitis within the Italian population. This study aimed to identify discrete profiles of Italian children hospitalized with bronchiolitis using a clustering approach and to compare findings with those obtained in international cohorts.

METHODS

This was a retrospective single-centre study conducted on children aged ≤2 years hospitalised with bronchiolitis (n = 401) at the Department of Infectious Diseases and the University Department of General Pediatrics in "Giovanni Di Cristina" Pediatric Hospital of Palermo, Italy, between November 2012 and May 2019. Bronchiolitis profiles were determined by latent class analysis, classifying children based on clinical characteristics at admission and viral aetiology.

RESULTS

Three profiles were identified. Class 1 (49%) was composed of 45% male children; all children were aged ≤6 months at hospitalization; 77% were infected with RSV; 100% had respiratory distress, 11% had apnea and none had cough. Class 2 (77%) was mainly composed of male subjects (51%); 19% were aged > 6 months at admission; 37% were infected with RSV; 12% had respiratory distress, 5% had apnea and 90% had cough. Class 3 (19%) included the largest proportion of male subjects (94%) and was mostly composed of children aged > 6 months at the time of admission (68%); 70% had cough, 12% showed respiratory distress and none presented with apnoea. Children in Class 1 were more frequently born near the epidemic season (p = 0.028); breastfeeding duration was significantly longer for children in Class 3 (p = 0.004).

CONCLUSIONS

The study identified distinct clinical profiles of bronchiolitis by a clustering approach in a single-centre study of children hospitalised for bronchiolitis in Italy. The three bronchiolitis profiles share some similarities with those identified in international studies using the same statistical approach. These findings may help to increase the understanding of the phenotypic variability that typically characterizes bronchiolitis, with relevant implications for future research.

Management of Asthma in the Preschool Child

The management of asthma in the preschool population is challenging because disease phenotypes are heterogeneous and evolving. Available therapies aimed at preventing persistent symptoms and recurrent exacerbations include inhaled corticosteroids and leukotriene receptor antagonists; episodic use of inhaled corticosteroids and azithromycin may result in a decrease in exacerbations among children with intermittent disease. This article reviews an approach using patient characteristics for selecting initial treatment approaches based on disease phenotype, such as symptom patterns or evidence of atopic markers. Evidence for and against the use of oral corticosteroids during acute episodes and barriers to adherence and effective treatment are discussed.

Things We Do for No Reason: Systemic Corticosteroids for Wheezing in Preschool-Aged Children

Wheezing is common in preschool-aged children (ages 2-5 years), with up to half in this age group having experienced a wheezing episode and up to one-third, recurrent wheezing.1,2 Young children with wheezing require ED visits and hospitalizations at much higher rates than older children and adults.3 Several studies have also demonstrated that children in this age group have higher rates of SCS prescriptions compared with older children.4,5 Despite the high prevalence of wheezing in this age group, there is great heterogeneity in the etiology and clinical progression of early childhood wheezing, with up to six described phenotypes each with varying levels of association with the development of asthma.6 Given the high frequency of asthma, preschool-aged children admitted with wheezing are often treated with SCS, as this is the standard of care for an acute asthma exacerbation.7

Severe bronchiolitis profiles and risk of recurrent wheeze by age 3 years

BACKGROUND

A better understanding of bronchiolitis heterogeneity might help clarify its relationship with the development of recurrent wheezing and asthma.

OBJECTIVES

We sought to identify severe bronchiolitis profiles using a clustering approach and to investigate for the first time their association with allergy/inflammatory biomarkers, nasopharyngeal microbiota, and development of recurrent wheezing by age 3 years.

METHODS

We analyzed data from a prospective, 17-center US cohort study of 921 infants (age <1 year) hospitalized with bronchiolitis (2011-2014 winters) with posthospitalization follow-up. Severe bronchiolitis profiles at baseline (hospitalization) were determined by using latent class analysis based on clinical factors and viral etiology. Blood biomarkers and nasopharyngeal microbiota profiles were determined by using samples collected within 24 hours of hospitalization. Recurrent wheezing by age 3 years was defined based on parental report of breathing problem episodes after discharge.

RESULTS

Three severe bronchiolitis profiles were identified: profile A (15%), which was characterized by a history of breathing problems/eczema during infancy and non-respiratory syncytial virus (mostly rhinovirus) infection; profile B (49%), which has the largest probability of respiratory syncytial virus infection and resembled classic respiratory syncytial virus-induced bronchiolitis; and profile C (36%), which was composed of the most severely ill group. Profile A infants had higher eosinophil counts, higher cathelicidin levels, and increased proportions of Haemophilus-dominant or Moraxella-dominant microbiota profiles. Compared with profile B, we observed significantly increased risk of recurrent wheezing in children with profile A (hazard ratio, 2.64; 95% CI, 1.90-3.68) and, to a lesser extent, with profile C (hazard ratio, 1.51; 95% CI, 1.14-2.01).

CONCLUSION

Although longer follow-up is needed, our results might help identify, among children hospitalized for bronchiolitis, subgroups with particularly increased risk of asthma.

The potential impact of paternal age on risk of asthma in childhood: a study within the Danish National Birth Cohort

BACKGROUND

Advanced paternal age has been associated with offspring morbidity and mortality, possibly due to de novo mutations and epigenetic changes in male germ cells. Epigenetic changes in the cord blood cells have been linked to asthma symptoms in offspring, but the role of paternal age has been less studied.

METHODS

From the Danish National Birth Cohort, 48,785 children who completed the 7-year follow-up were included. Parental reports of physician-diagnosed asthma had been obtained by a posted or web-based questionnaire. Paternal age at delivery was obtained through linkage with maternal civil registration number in the Danish Civil Registration System and classified into four groups: ≤24, 25-34 (reference), 35-39, and >40 years. We calculated the prevalence proportion of asthma and prevalence ratios (PRs) with 95% confidence intervals (CIs) using log-binomial regression, adjusting for paternal smoking, paternal asthma, and paternal socioeconomic status.

RESULTS

At the 7-year follow-up, 5875 children (12%) had physician-diagnosed asthma. The prevalence of asthma in 7-year old children was higher with paternal age of ≤24 (adjusted PR 1.40; 95% CI: 1.26; 1.55) and lower with the paternal age of ≥35 years (adjusted PR 0.84; 95% CI: 0.78; 0.89) compared to the reference group.

CONCLUSIONS

Paternal age of ≥35 years was associated with a lower prevalence of asthma in childhood, and paternal age of ≤24 years with higher prevalence compared with paternal age of 25-34 years. The potential causes of higher asthma prevalence among offspring of young fathers warrant further investigation.