Adult non-cystic fibrosis bronchiectasis is characterised by airway luminal Th17 pathway activation

PLoS One. 2015 Mar 30;10(3):e0119325. doi: 10.1371/journal.pone.0119325. eCollection 2015.

Abstract

Background: Non-cystic fibrosis (CF) bronchiectasis is characterised by chronic airway infection and neutrophilic inflammation, which we hypothesised would be associated with Th17 pathway activation.

Methods: Th17 pathway cytokines were quantified in bronchoalveolar lavage fluid (BALF), and gene expression of IL-17A, IL-1β, IL-8 and IL-23 determined from endobronchial biopsies (EBx) in 41 stable bronchiectasis subjects and 20 healthy controls. Relationships between IL-17A levels and infection status, important clinical measures and subsequent Pseudomonas aeruginosa infection were determined.

Results: BALF levels of all Th17 cytokines (median (IQR) pg/mL) were significantly higher in bronchiectasis than control subjects, including IL-17A (1.73 (1.19, 3.23) vs. 0.27 (0.24, 0.35), 95% CI 1.05 to 2.21, p<0.0001) and IL-23 (9.48 (4.79, 15.75) vs. 0.70 (0.43, 1.79), 95% CI 4.68 to 11.21, p<0.0001). However, BALF IL-17A levels were not associated with clinical measures or airway microbiology, nor predictive of subsequent P. aeruginosa infection. Furthermore, gene expression of IL-17A in bronchiectasis EBx did not differ from control. In contrast, gene expression (relative to medians of controls) in bronchiectasis EBx was significantly higher than control for IL1β (4.12 (1.24, 8.05) vs 1 (0.13, 2.95), 95% CI 0.05 to 4.07, p = 0.04) and IL-8 (3.75 (1.64, 11.27) vs 1 (0.54, 3.89), 95% CI 0.32 to 4.87, p = 0.02) and BALF IL-8 and IL-1α levels showed significant relationships with clinical measures and airway microbiology. P. aeruginosa infection was associated with increased levels of IL-8 while Haemophilus influenzae was associated with increased IL-1α.

Conclusions and clinical relevance: Established adult non-CF bronchiectasis is characterised by luminal Th17 pathway activation, however this pathway may be relatively less important than activation of non-antigen-specific innate neutrophilic immunity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Bronchiectasis / metabolism*
  • Bronchiectasis / pathology
  • Bronchoalveolar Lavage Fluid / cytology*
  • Bronchoalveolar Lavage Fluid / microbiology
  • Case-Control Studies
  • Female
  • Haemophilus influenzae / isolation & purification
  • Humans
  • Interleukins / genetics
  • Interleukins / metabolism
  • Male
  • Middle Aged
  • Pseudomonas aeruginosa / isolation & purification
  • Th17 Cells / metabolism*

Substances

  • Interleukins

Grants and funding

This study was internally funded by the Mater Adult Respiratory Research Trust Fund. MAM is supported by a NHMRC (National Health and Medical Research Council) Senior Research Fellowship. No pharmaceutical company or other agency (including medical writers) had any role in this study. DJS had full access to all study data, vouches for the integrity of the data and its presentation and had final responsibility for the decision to submit for publication.