Antimicrobial peptides (AMPs) are effectors of host defence against infection, inflammation and wound repair. We aimed to study AMP levels in stable chronic obstructive pulmonary disease (COPD) and during acute exacerbations of COPD (AECOPD), and to examine their relation to clinical parameters and inflammatory markers.
The 3-year Bergen COPD Cohort Study included 433 COPD patients and 325 controls. Induced sputum was obtained and analysed for levels of the AMPs human cathelicidin (hCAP18/LL-37) and secretory leukocyte protease inhibitor (SLPI), and for the inflammatory markers interleukin (IL)-8, IL-6 and tumour necrosis factor-α (TNF-α) using immunoassays. Systemic hCAP18/LL-37 and vitamin D levels were also studied. Treating AMPs as response variables, non-parametric tests were applied for univariate comparison, and linear regression to obtain adjusted estimates. The risk of AECOPD was assessed by Cox proportional-hazard regression.
Sputum AMP levels were higher in patients with stable COPD (n=215) compared to controls (n=45), and further changed during AECOPD (n=56), with increased hCAP18/LL-37 and decreased SLPI levels. Plasma hCAP18/LL-37 levels showed a similar pattern. In stable COPD, high sputum hCAP18/LL-37 levels were associated with increased risk of AECOPD, non-typeable Haemophilus influenzae colonisation, higher age, ex-smoking and higher levels of inflammatory markers.
Altered levels of selected AMPs are linked to airway inflammation, infection and AECOPD, suggesting a role for these peptides in airway defence mechanisms in COPD.
Sputum AMP patterns are associated with airway microbial presence, inflammatory markers and clinical outcomes in COPD http://ow.ly/qVFi306wBNW
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Support statement: This study was funded by the Bergen Medical Research Foundation, Bergen, Norway; the Centre for Clinical Research, Haukeland University Hospital, Bergen, Norway; the Dept of Thoracic Medicine, Haukeland University Hospital, Bergen, Norway; the Foundation for Respiratory Research, University of Bergen, Bergen, Norway; and the Norwegian ExtraFoundation for Health and Rehabilitation, Norway. Funding information for this article has been deposited with the Open Funder Registry.
Conflict of interest: Disclosures can be found alongside this article at erj.ersjournals.com
- Received July 5, 2016.
- Accepted November 16, 2016.
- Copyright ©ERS 2017