Correlation between levels of exhaled hydrogen sulfide and airway inflammatory phenotype in patients with chronic persistent asthma

Background and objective Endogenous hydrogen sulfide ( H 2 S ) may be a biomarker of asthma severity and activity. However, the relationship between exhaled H 2 S and airway inflammation phenotypes in asthma remains unclear. This study examined associations between endogenous H 2 S and chronic airway inflammatory phenotypes in patients with chronic persistent asthma. Methods One hundred forty‐eight patients (47 males, 101 females, 47.4 ± 15.3 years old) with chronic persistent asthma were enrolled. Induced sputum cells were examined, and patients were grouped according to sputum inflammatory cell composition. Baseline demographics, A sthma C ontrol T est ( ACT ) scores, spirometry data and H 2 S levels in exhaled air and plasma were obtained for all patients. Results The eosinophilic, neutrophilic, mixed granulocytic and paucigranulocytic inflammation groups included 57 (38.5%), 28 (18.9%), 23 (15.5%) and 40 (27%) subjects, respectively. The paucigranulocytic group had the best lung function, and patients with eosinophilic inflammation had lower ACT scores than patients with paucigranulocytic findings. In the eosinophilic group, lower exhaled H 2 S were found and exhaled H 2 S levels were negatively correlated with sputum eosinophil counts (R = −0.428, P  < 0.01). Exhaled H 2 S levels were positively correlated with percent of predicted forced expiratory volume in 1 s (R = 0.567, P  < 0.01) and ACT score (R = 0.519, P  < 0.01). Conclusions Exhaled H 2 S may be a useful marker of airway inflammation in asthma.