Bronchoalveolar lavage profiles in uncontrolled wheezy children compared by asthma predictive index

Functional immunophenotyping of blood neutrophils identifies novel endotypes of viral response in preschool children with recurrent wheezing

BACKGROUND

Preschool children with recurrent wheezing are heterogeneous, with differing responses to respiratory viral infections. Although neutrophils are crucial for host defense, their function has not been studied in this population.

OBJECTIVE

We performed functional immunophenotyping on isolated blood neutrophils from 52 preschool children with recurrent wheezing (aeroallergen sensitization, n = 16; no sensitization, n = 36).

METHODS

Blood neutrophils were purified and cultured overnight with polyinosinic:polycytidylic acid [poly(I:C)] as a viral analog stimulus. Neutrophils underwent next-generation sequencing with Reactome pathway analysis and were analyzed for cytokine secretion, apoptosis, myeloperoxidase, and extracellular DNA release. CD14+ monocytes were also exposed to neutrophil culture supernatant and analyzed for markers of M1 and M2 activation.

RESULTS

A total of 495 genes, related largely to the innate immune system and neutrophil degranulation, were differently expressed in children with versus without aeroallergen sensitization. Functional experiments identified more neutrophil degranulation and extracellular trap formation (ie, more myeloperoxidase and extracellular DNA) and less neutrophil proinflammatory cytokine secretion in children with aeroallergen sensitization. Neutrophils also shifted CD14+ monocytes to a more anti-inflammatory (ie, M2) phenotype in sensitized children and a more proinflammatory (ie, M1) phenotype in nonsensitized children. Although both groups experienced viral exacerbations, annualized exacerbation rates prompting unscheduled health care were also higher in children without aeroallergen sensitization after enrollment.

CONCLUSIONS

Systemic neutrophil responses to viral infection differ by allergic phenotype and may be less effective in preschool children without allergic inflammation. Further studies of neutrophil function are needed in this population, which often has less favorable therapeutic responses to inhaled corticosteroids and other therapies directed at type 2-high inflammation.

Demystifying controversies in preschool wheeze

INTRODUCTION

Wheezing disorders in preschool children are common. Current treatment approaches assume all preschool wheezers are the same and will respond to a short course of oral corticosteroids (OCS) during acute attacks and subsequent maintenance inhaled corticosteroids (ICS) to prevent future attacks. But we have increasing evidence showing preschool wheezing disorders are markedly heterogeneous and the response to corticosteroids either during acute attacks or as maintenance therapy can be variable between patients and is determined by disease severity and underlying pathological phenotype.

AREAS COVERED

The aim of this review is to discuss recent evidence which will help to explain a few critical pathophysiological concepts that are often misunderstood, thus helping to demystify the controversies that often surround preschool wheezing disorders and can contribute to ineffective management.

EXPERT OPINION

Preschool wheezing disorders are distinct from school-age allergic asthma. There is little evidence to support the use of oral corticosteroids for acute attacks. A staged approach to confirm the diagnosis, and objective tests to determine the pathological phenotype of preschool wheeze is essential prior to initiating maintenance therapy to control symptoms and prevent attacks in children with recurrent preschool wheeze.

Blood Eosinophils for Prediction of Exacerbation in Preschool Children With Recurrent Wheezing

BACKGROUND

Although clinical features of type 2 inflammation have been associated with poorer longitudinal outcomes in preschool children with recurrent wheezing, it remains difficult to predict which children are at highest risk for poor outcomes during a routine clinical encounter.

OBJECTIVE

We tested the hypothesis that prespecified cut points of blood eosinophil counts would predict exacerbation and treatment response outcomes in preschool children with recurrent wheezing and that prediction could be improved with the addition of a second biomarker.

METHODS

Data from 3 clinical trials of 1,074 preschool children aged 12 to 71 months with recurrent wheezing were merged. The primary outcome was the occurrence of any exacerbation during follow-up. Secondary outcomes included the annualized rate of wheezing exacerbations and the occurrence of any exacerbation requiring hospitalization. Exploratory analyses focused on exacerbation outcomes, offline exhaled nitric oxide concentrations, and caregiver-reported asthma control scores after inhaled corticosteroid treatment initiation.

RESULTS

Each blood eosinophil cut point was associated with increased odds of exacerbation, higher exacerbation rates, and greater hospitalization occurrence in preschool children with recurrent wheezing. However, outcome detection was improved in children with more elevated blood eosinophil counts. Addition of a second biomarker of type 2 inflammation improved outcome detection and was further associated with an improved response to initiation of daily inhaled corticosteroids in exploratory analyses. However, the specificity of blood eosinophils was poor.

CONCLUSIONS

Although validation studies are warranted, blood eosinophil cut points may be useful for clinical assessment and future studies of exacerbation and treatment response in preschool children with recurrent wheezing.

Pediatric pulmonology 2021 year in review: Asthma

Asthma is the most common chronic disease in children, affecting an estimated 6.1 million children in the United States. SARS-CoV2 had a significant impact on asthma exacerbations and healthcare utilization of patients with asthma in 2021. Additionally, studies in 2021 influenced the field of asthma with improvements in diagnostic testing and monitoring, treatment of severe exacerbations, social determinants of health, and evaluation of medical costs. This article is part of our 2021 "Year in Review" series, in which we summarize publications in major pulmonary topics, in the context of selected literature from other journals relevant to our discipline.