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

Background and objectiveEndogenous hydrogen sulfide (H2S) may be a biomarker of asthma severity and activity. However, the relationship between exhaled H2S and airway inflammation phenotypes in asthma remains unclear. This study examined associations between endogenous H2S and chronic airway inflammatory phenotypes in patients with chronic persistent asthma. MethodsOne hundred forty-eight patients (47 males, 101 females, 47.415.3 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, Asthma Control Test (ACT) scores, spirometry data and H2S levels in exhaled air and plasma were obtained for all patients. ResultsThe 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 H2S were found and exhaled H2S levels were negatively correlated with sputum eosinophil counts (R=-0.428, P<0.01). Exhaled H2S levels were positively correlated with percent of predicted forced expiratory volume in 1s (R=0.567, P<0.01) and ACT score (R=0.519, P<0.01). ConclusionsExhaled H2S may be a useful marker of airway inflammation in asthma. The aim of this study was to examine the correlation between endogenous H2S and chronic airway inflammation in patients with chronic persistent asthma. Patients were grouped using induced sputum as predominantly eosinophilic, neutrophilic, mixed granulocytic or paucigranulocytic. Exhaled H2S may be a useful marker of airway inflammation in asthma.