Different inflammatory phenotypes in adults and children with acute asthma

Abstract

Inflammatory phenotypes are recognised in stable adult asthma, but are less well established in childhood and acute asthma. Additionally, Chlamydophila pneumoniae infection as a cause of noneosinophilic asthma is controversial. This study examined the prevalence of inflammatory phenotypes and the presence of current C. pneumoniae infection in adults and children with stable and acute asthma.Adults with stable (n529) or acute (n522) asthma, healthy adults (n511), children with stable (n549) or acute (n528) asthma, and healthy children (n59) underwent clinical assessment and sputum induction. Sputum was assessed for inflammatory cells, and DNA was extracted from sputum cell suspensions and supernatants for C. pneumoniae detection using real-time PCR.The asthma phenotype was predominantly eosinophilic in children with acute asthma (50%) but neutrophilic in adults with acute asthma (82%). Paucigranulocytic asthma was the most common phenotype in both adults and children with stable asthma. C. pneumoniae was not detected in 99% of samples.The pattern of inflammatory phenotypes differs between adults and children, with eosinophilic inflammation being more prevalent in both acute and stable childhood asthma, and neutrophilic inflammation being the dominant pattern of acute asthma in adults. The aetiology of neutrophilic asthma is unknown and is not explained by the presence of current active C. pneumoniae infection.

Two novel, severe asthma phenotypes identified during childhood using a clustering approach

“…Many studies have shown an association between the severity of asthma and neutrophilic inflammation detected by induced sputum [24,25]. Furthermore, our study supports the findings of SIROUX et al [26] who reported that the phenotype of ''active treated allergic childhood-onset asthma'' is associated with blood eosinophilia, while ''active treated adult-onset asthma'' is associated with blood neutrophils.…”

Novel concepts in airway inflammation and remodelling in asthma

“…Similarly, in adults on inhaled steroid therapy, the sputum inflammatory profile commonly changed in subjects with both moderate and severe asthma over 1 year, and only one-third of subjects had a stable phenotype [23]. Given the relative instability of airway inflammation in asthma and the added complication of changes in inflammation during exacerbations [24], it is unlikely that management based on inflammatory phenotype alone is sufficient. An interesting point about the subset of patients that do have persistently noneosinophilic disease is their poor response to inhaled steroids [25].…”

Untangling asthma phenotypes and endotypes

“…However, as longitudinal studies are lacking, it remains unclear whether neutrophilic asthma developed on a background of long-standing eosinophilic asthma or recurrent or persistent bacterial infections superimposed on the background of a previously eosinophilic asthma. Less is known about the incidence of neutrophilic asthma in children, where eosinophilic asthma seems to predominate both in acute and in stable disease (12). Neutrophilic inflammation appears more frequent in children with nonatopic asthma (36).…”

“…In addition, inflammatory phenotypes appear to differ with age. Eosinophilic inflammation is more prevalent in both acute and stable childhood asthma, while neutrophilic inflammation is more frequent in acute asthma in older adults (12). In intrinsic asthma, which is frequently of late onset, eosinophils predominate (13).…”