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Published on: April 13, 2010
Exhaled nitric oxide identifies the persistent eosinophilic phenotype in severe refractory asthma
Philip E Silkoff1, Anne M Lent, Ashley A Busacker
1National Jewish Medical and Research Center, Narbeth, PA 19072, USA. philsilkoff@hotmail.com
The Journal of Allergy and Clinical Immunology
|December 13, 2005
Summary
Fractional exhaled nitric oxide (FENO) levels can identify severe refractory asthma patients with persistent eosinophilia, even after steroid treatment. This finding highlights FENO as a potential biomarker for steroid resistance in asthma management.
Area of Science:
- Pulmonology
- Allergy and Immunology
- Biomarkers
Background:
- Fractional exhaled nitric oxide (FENO) is elevated in asthma and linked to eosinophilic inflammation, decreasing with steroid therapy.
- Severe refractory asthma (SRA) presents challenges in management, with potential steroid resistance.
- Understanding biomarkers for persistent inflammation in SRA is crucial.
Purpose of the Study:
- To investigate if elevated FENO levels persist in severe refractory asthma (SRA) patients with ongoing eosinophilia despite steroid therapy.
- To assess FENO as an indicator of steroid resistance in SRA.
- To correlate FENO levels with specific inflammatory cell counts in SRA.
Main Methods:
- FENO measurements were performed in subjects with SRA, mild-moderate asthma, and healthy controls.
- Endobronchial biopsy and bronchoalveolar lavage were conducted for inflammatory cell assessment.
- Eosinophil status (EOS+/EOS-) was determined in SRA subjects.
Main Results:
- SRA patients with eosinophilia (EOS+ SRA) exhibited significantly higher FENO levels than EOS- SRA patients and other groups.
- FENO levels in SRA correlated positively with tissue eosinophils, lymphocytes, and mast cells.
- A FENO threshold of 72.9 ppb demonstrated high specificity (1.0) for identifying EOS+ status in SRA.
Conclusions:
- FENO measurement effectively identifies SRA patients with persistent eosinophilia, indicating potential steroid resistance.
- FENO serves as a valuable non-invasive biomarker for detecting eosinophilic inflammation in SRA.
- Further research is warranted to explore FENO's role in monitoring therapeutic responses in SRA over time.
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