Abstract 248 w
Background. Because of altered airway microbiome in asthma, we
analysed the bacterial species in sputum of patients with severe asthma.
Methods. Whole genome sequencing was performed on induced sputum
from non-smoking (SAn) and current or ex-smoker (SAs/ex) severe asthma
patients, mild/moderate asthma (MMA) and healthy controls (HC). Data was
analysed by asthma severity, inflammatory status and
transcriptome-associated clusters (TACs).
Results. α-diversity at the species level was lower in SAn and
SAs/ex, with an increase in Haemophilus influenzae andMoraxella catarrhalis, and Haemophilus influenzae andTropheryma whipplei, respectively, compared to HC. In
neutrophilic asthma, there was greater abundance of Haemophilus
influenzae and Moraxella catarrhalis and in eosinophilic asthma,Tropheryma whipplei was increased. There was a reduction in
α-diversity in TAC1 and TAC2 that expressed high levels ofHaemophilus influenzae and Tropheryma whipplei, andHaemophilus influenzae and Moraxella catarrhalis ,
respectively, compared to HC. Sputum neutrophils correlated positively
with Moraxella catarrhalis and negatively with Prevotella ,Neisseria and Veillonella species and Haemophilus
parainfluenzae . Sputum eosinophils correlated positively withTropheryma whipplei which correlated with pack-years of smoking.
α- and β-diversities were stable at one year.
Conclusions. Haemophilus influenzae and Moraxella
catarrhalis were more abundant in severe neutrophilic asthma and TAC2
linked to inflammasome and neutrophil activation, whileHaemophilus influenzae and Tropheryma whipplei were
highest in SAs/ex and in TAC1 associated with highest expression of
IL-13 Type 2 and ILC2 signatures with the abundance of Tropheryma
whipplei correlating positively with sputum eosinophils. Whether these
bacterial species drive the inflammatory response in asthma needs
evaluation.