Objectives: Hydrogen sulfide (H 2 S) is a gas produced by respiratory cells including smooth muscle cells and may play a role as a cellular gasotransmitter. We evaluated whether H 2 S levels in serum or sputum could represent a new biomarker of COPD in a cross-sectional study. Methods: H 2 S levels in sputum and serum samples were measured using a sulfide-sensitive electrode in 64 patients with stable COPD (S-COPD), 29 COPD subjects during acute exacerbation (AE-COPD), 14 healthy smokers and 21 healthy non-smokers. Results: Sputum H 2 S levels in AE-COPD subjects were higher than those in S-COPD, healthy smoking and non-smoking subjects (p<0.001), but serum H 2 S levels in AECOPD were lower than those in S-COPD (p<0.001). Thus, the sputum-to-serum ratio of H 2 S (H 2 S ratio) in AE-COPD subjects were higher than those in stable COPD, healthy smoking and non-smoking subjects ( p<0.001). In 14 COPD subjects whose H 2 S ratios were measured during and after an exacerbation, the mean ratio was increased during exacerbation (p<0.05). H 2 S ratio was positively correlated with St. George's Respiratory Questionnaire score, sputum neutrophils and IL-6 and IL-8 levels in sputum and serum (p<0.01) but inversely correlated with sputum macrophages (%), FEV 1 %predicted and FEV 1 /FVC (p<0.01). The cut-off level of H 2 S ratio to indicate an exacerbation was ≥ 0.44 (sensitivity of 93.1% and specificity of 84.5%). Conclusions: The ratio of sputum-to-serum levels of H 2 S may provide a useful marker of COPD indicative of obstructive neutrophilic inflammation and of potential ongoing exacerbation.
CITATION STYLE
Saito, J., Mackay, A. J., Rossios, C., Gibeon, D., Macedo, P., Sinharay, R., … Chung, K. F. (2014). Sputum-to-serum hydrogen sulfide ratio in COPD. Thorax, 69(10), 903–909. https://doi.org/10.1136/thoraxjnl-2013-204868
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