Eosinophilic airway inflammation in asthmatic patients is associated with an altered airway microbiome

Research output: Contribution to journalArticle

Abstract

Background: Asthmatic patients have higher microbiome diversity and an altered composition, with more Proteobacteria and less Bacteroidetes compared with healthy control subjects. Studies comparing airway inflammation and the airway microbiome are sparse, especially in subjects not receiving anti-inflammatory treatment. Objective: We sought to describe the relationship between the airway microbiome and patterns of airway inflammation in steroid-free patients with asthma and healthy control subjects. Methods: Bronchoalveolar lavage fluid was collected from 23 steroid-free nonsmoking patients with asthma and 10 healthy control subjects. Bacterial DNA was extracted from and subjected to Illumina MiSeq sequencing of the 16S rDNA V4 region. Eosinophils and neutrophils in the submucosa were quantified by means of immunohistochemical identification and computerized image analysis. Induced sputum was obtained, and airway hyperresponsiveness to mannitol and fraction of exhaled nitric oxide values were measured. Relationships between airway microbial diversity and composition and inflammatory profiles were analyzed. Results: In asthmatic patients airway microbial composition was associated with airway eosinophilia and AHR to mannitol but not airway neutrophilia. The overall composition of the airway microbiome of asthmatic patients with the lowest levels of eosinophils but not asthmatic patients with the highest levels of eosinophils deviated significantly from that of healthy subjects. Asthmatic patients with the lowest levels of eosinophils had an altered bacterial abundance profile, with more Neisseria, Bacteroides, and Rothia species and less Sphingomonas, Halomonas, and Aeribacillus species compared with asthmatic patients with more eosinophils and healthy control subjects. Conclusion: The level of eosinophilic airway inflammation correlates with variations in the microbiome across asthmatic patients, whereas neutrophilic airway inflammation does not. This warrants further investigation on molecular pathways involved in both patients with eosinophilic and those with noneosinophilic asthma.

Details

Authors
  • Asger Sverrild
  • Pia Kiilerich
  • Asker Brejnrod
  • Rebecca Pedersen
  • Celeste Porsbjerg
  • Anders Bergqvist
  • Jonas S. Erjefält
  • Karsten Kristiansen
  • Vibeke Backer
Organisations
External organisations
  • Bispebjerg Hospital
  • University of Copenhagen
  • Danish Serum Institute, Copenhagen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Respiratory Medicine and Allergy

Keywords

  • Airway inflammation, Asthma, Bacteria, Bronchoalveolar lavage, Microbiome, Noneosinophilic asthma
Original languageEnglish
Pages (from-to)407-417.e11
JournalJournal of Allergy and Clinical Immunology
Volume140
Issue number2
Early online date2016 Dec 29
Publication statusPublished - 2017
Publication categoryResearch
Peer-reviewedYes