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The following is a summary of “Discovery and Validation of a Volatile Signature of Eosinophilic Airway Inflammation in Asthma,” published in the October 2024 issue of Pulmonology by Peltrini et al. 

Researchers conducted a retrospective study to develop a volatile biomarker signature to predict sputum eosinophilia in asthma, focusing on volatile organic compounds (VOCs) in asthmatic breath.   

They collected VOCs emitted from headspace samples of 36 patients with severe asthma onto sorbent tubes and analyzed them using thermal desorption gas chromatography–mass spectrometry (GC-MS). Elastic net regression identified stable VOCs associated with sputum eosinophilia ⩾3% and generated a volatile biomarker signature. This signature was validated in breath samples from 65 patients with acute asthma in the UK EMBER (East Midlands Breathomics Pathology Node) consortium with blood eosinophilia ⩾0.3 × 10⁹ cells/L or sputum eosinophilia ⩾3%, and 42 patients in the U-BIOPRED-IMI (Unbiased Biomarkers in Prediction of Respiratory Disease Outcomes Innovative Medicines Initiative) consortium. Breath samples were collected onto sorbent tubes (EMBER) or Tedlar bags (U-BIOPRED) and analyzed by GC-MS (GC × GC-MS for EMBER or GC-MS for U-BIOPRED).  

The results showed that 19 VOCs were identified in the in vitro headspace and associated with sputum eosinophilia. The VOC signature demonstrated an excellent diagnostic accuracy for sputum eosinophilia ⩾3%, with an area under the receiver operating characteristic curve (AUROC) of 0.90 (95% CI, 0.80–0.99; P < 0.0001). It showed an inverse correlation with sputum eosinophil percentage (r_s= −0.71; P < 0.0001) and outperformed fractional exhaled nitric oxide, which had an AUROC of 0.61 (95% CI, 0.35–0.86). In replication cohorts, the VOC signature exhibited AUROC values of 0.89 (95% CI, 0.76–1.0) for acute asthma exacerbations in the EMBER cohort with sputum eosinophilia and 0.90 (95% CI, 0.75–1.0) in the U-BIOPRED, both surpassing fractional exhaled nitric oxide in U-BIOPRED (AUROC 0.62 [0.33–0.90]).  

Investigators concluded a volatile biomarker signature linked to eosinophilic airway inflammation identified and clinically validated at an early stage. 

Source: atsjournals.org/doi/10.1164/rccm.202310-1759OC