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Neutrophilic inflammation in severe persistent asthma
A Jatakanon1, C Uasuf, W Maziak
1Department of Thoracic Medicine, Imperial College School of Medicine, National Heart and Lung Institute, London, United Kingdom.
American Journal of Respiratory and Critical Care Medicine
|November 11, 1999
Summary
Neutrophils are increasingly present in severe asthma, indicating a potential role beyond eosinophils in airway inflammation. This study compared sputum profiles and exhaled nitric oxide (NO) across asthma severities.
Area of Science:
- Pulmonology
- Immunology
- Respiratory Medicine
Background:
- Airway inflammation in severe asthma is not fully understood, though neutrophils may be involved.
- Asthma severity is classified based on clinical features and medication requirements.
- Exhaled nitric oxide (NO) is a noninvasive marker for airway inflammation.
Purpose of the Study:
- To compare induced sputum profiles in patients with mild, moderate, and severe asthma versus normal controls.
- To investigate the role of neutrophils and eosinophils in different asthma severities.
- To assess exhaled nitric oxide (NO) levels as a marker of inflammation.
Main Methods:
- Induced sputum analysis was performed on non-smoking patients with varying asthma severity and healthy controls.
- Sputum cell counts (neutrophils, eosinophils) and inflammatory markers (IL-8, MPO, IL-5, ECP) were measured.
- Exhaled nitric oxide (NO) levels were measured as a noninvasive inflammatory marker.
Main Results:
- Neutrophil numbers were significantly higher in severe asthma compared to mild asthma and controls.
- Interleukin-8 (IL-8) and neutrophil myeloperoxidase (MPO) levels were elevated in severe asthma.
- Eosinophil counts were increased in both mild and severe asthma, with differing levels of associated cytokines/proteins.
Conclusions:
- Neutrophils likely play a significant role in the airway inflammation of severe asthma.
- While eosinophils are confirmed players, neutrophils may be a key factor in more severe disease.
- Exhaled NO levels were not significantly different in patients on corticosteroids, regardless of severity.