Recent research has shown that the
bacterial constituents of lungs from patients with asthma differ markedly from
their non-asthma comparators.
Specifically, asthma lungs have increased predominance of Proteobacteria
as well as higher bacterial load. These
findings came from subjects on chronic ICS therapy, which is known to be
immunosuppressive. Marri et al. in this
month’s issue present important results from their investigation on lung
bacteria from asthma patients not on ICS therapy (J Allergy Clin Immunol 2013; 131(2): 346-352).
The authors analyzed induced sputum from
10 asthma subjects and 10 non-asthma subjects.
Bacterial 16s rRNA was sequenced and compared to data from the Ribosomal
Database Project. All samples contained
5 phyla of bacteria, Firmicutes, Proteobacteria, Actinobacteria, Fusobacteria,
and Bacteroides. Sputum from asthma
subjects had significantly higher percentages of Proteobacteria with a
concordant drop in Firmicutes prevalence as compared to sputum from non-asthma
subjects. They also found increased
bacterial load in the asthma subjects as well as increased bacterial
diversity. Marri et al. report a higher
relative abundance of bacterial families that contain Moraxella catarrhalis and Haemophilus influenza in asthma subjects,
potentially implicating these pathogens in asthma pathogenesis. They also note that atopic status did not
influence the results.
