Blood and sputum eosinophils in COPD; relationship with bacterial load

Respiratory Research

Research

Gavin C. Donaldson¹  Richa Singh¹  Jadwiga A. Wedzicha¹  Timothy D. McHugh²  Sarah Thurston²  Anthony J Brookes³  Adam J. Webb³  Christopher E. Brightling⁴  Leena George⁴  Bethan L. Barker⁴  Vandana Gupta⁵  Dave Singh⁶  Umme Kolsum⁶ 

[1] Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, UK;Centre for Clinical Microbiology, University College London, London, UK;Department of Genetics, University of Leicester, Leicester, UK;Department of Infection, Immunity, and Inflammation, Institute for Lung Health, NIHR Respiratory Biomedical Research Unit, University of Leicester, Leicester, UK;Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester and University Hospital of South Manchester NHS Foundation Trust, M23 9QZ, Manchester, UK;Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester and University Hospital of South Manchester NHS Foundation Trust, M23 9QZ, Manchester, UK;The Medicines Evaluation Unit, Manchester, UK;

关键词: Pulmonary eosinophilia;    COPD exacerbations;    Bacterial infections;   

DOI  :  10.1186/s12931-017-0570-5

 received in 2017-03-01, accepted in 2017-05-01,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundSputum and blood eosinophil counts predict corticosteroid effects in COPD patients. Bacterial infection causes increased airway neutrophilic inflammation. The relationship of eosinophil counts with airway bacterial load in COPD patients is uncertain. We tested the hypothesis that bacterial load and eosinophil counts are inversely related.MethodsCOPD patients were seen at stable state and exacerbation onset. Sputum was processed for quantitative polymerase chain reaction detection of the potentially pathogenic microorganisms (PPM) H. influenzae, M. catarrhalis and S. pneumoniae. PPM positive was defined as total load ≥1 × 104copies/ml. Sputum and whole blood were analysed for differential cell counts.ResultsAt baseline, bacterial counts were not related to blood eosinophils, but sputum eosinophil % was significantly lower in patients with PPM positive compared to PPM negative samples (medians: 0.5% vs. 1.25% respectively, p = 0.01). Patients with PPM positive samples during an exacerbation had significantly lower blood eosinophil counts at exacerbation compared to baseline (medians: 0.17 × 109/L vs. 0.23 × 109/L respectively, p = 0.008), while no blood eosinophil change was observed with PPM negative samples.ConclusionsThese findings indicate an inverse relationship between bacterial infection and eosinophil counts. Bacterial infection may influence corticosteroid responsiveness by altering the profile of neutrophilic and eosinophilic inflammation.

【 授权许可】

CC BY   
© The Author(s). 2017