Neutrophilic airway inflammation in COPD and bronchiectasis
How smoke, bacteria and impaired clearance drive neutrophil recruitment, protease excess and oxidative stress in COPD and bronchiectasis, why it resists corticosteroids, and how macrolides, alpha-1 antitrypsin and DPP-1 inhibition fit the mechanism.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Neutrophilic inflammation dominates COPD, bronchiectasis, cystic fibrosis and a subset of severe asthma. Sputum neutrophils are 61% or more.
- The triggers are cigarette smoke, biomass smoke, bacterial colonisation (Haemophilus influenzae, Pseudomonas aeruginosa) and impaired mucus clearance.
- Neutrophils are drawn in by CXCL8 (IL-8), leukotriene B4 and IL-17. They release neutrophil elastase, proteinase 3, cathepsin G, MMP-9, reactive oxygen species and neutrophil extracellular traps (NETs).
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Sources
- The COPD-X Plan: Australian and New Zealand guidelines for the management of chronic obstructive pulmonary diseaseAU/NZLung Foundation Australia and Thoracic Society of Australia and New Zealand, V2.78, December 2025
- Global Strategy for the Diagnosis, Management and Prevention of COPD, 2026 reportGlobal Initiative for Chronic Obstructive Lung Disease (GOLD), 2026
- Chronic suppurative lung disease and bronchiectasis in children, adolescents and adults in Australia and New Zealand: TSANZ position statement summaryAU/NZThoracic Society of Australia and New Zealand (Medical Journal of Australia 2023;219(11), Grimwood et al), 2023
- Phase 3 trial of the DPP-1 inhibitor brensocatib in bronchiectasis (ASPEN)New England Journal of Medicine (Chalmers et al), 2025
- Azithromycin for prevention of exacerbations of COPDNew England Journal of Medicine (Albert et al), 2011
- Effect of azithromycin on asthma exacerbations and quality of life in adults with persistent uncontrolled asthma (AMAZES)AU/NZThe Lancet (Gibson et al), 2017
- Azithromycin for prevention of exacerbations in non-cystic fibrosis bronchiectasis (EMBRACE)The Lancet (Wong et al), 2012
- Chronic obstructive pulmonary diseaseNature Reviews Disease Primers (Barnes et al), 2015
- Last updated
- 14 November 2026
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