Junpei Saito1, Alex J Mackay2, Christos Rossios3, David Gibeon3, Patricia Macedo3, Rudy Sinharay3, Pankaj K Bhavsar4, Jadwiga A Wedzicha5, Kian Fan Chung3. 1. Section of Experimental Studies, National Heart and Lung Institute, Imperial College London, London, UK NIHR Respiratory Biomedical Research Unit at the Royal Brompton NHS Foundation Trust and Imperial College London, London, UK Department of Pulmonary Medicine, Fukushima Medical University, Fukushima, Japan. 2. Centre for Respiratory Medicine, University College London Medical School, Royal Free Campus, London, UK. 3. Section of Experimental Studies, National Heart and Lung Institute, Imperial College London, London, UK NIHR Respiratory Biomedical Research Unit at the Royal Brompton NHS Foundation Trust and Imperial College London, London, UK. 4. Section of Experimental Studies, National Heart and Lung Institute, Imperial College London, London, UK. 5. Department of Pulmonary Medicine, Fukushima Medical University, Fukushima, Japan.
Abstract
OBJECTIVES: Hydrogen sulfide (H₂S) is a gas produced by respiratory cells including smooth muscle cells and may play a role as a cellular gasotransmitter. We evaluated whether H₂S levels in serum or sputum could represent a new biomarker of COPD in a cross-sectional study. METHODS: H₂S 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 H₂S levels in AE-COPD subjects were higher than those in S-COPD, healthy smoking and non-smoking subjects (p<0.001), but serum H₂S levels in AE-COPD were lower than those in S-COPD (p<0.001). Thus, the sputum-to-serum ratio of H₂S (H₂S 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 H₂S ratios were measured during and after an exacerbation, the mean ratio was increased during exacerbation (p<0.05). H₂S 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 (%), FEV₁%predicted and FEV₁/FVC (p<0.01). The cut-off level of H₂S 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 H₂S may provide a useful marker of COPD indicative of obstructive neutrophilic inflammation and of potential ongoing exacerbation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
OBJECTIVES: Hydrogen sulfide (H₂S) is a gas produced by respiratory cells including smooth muscle cells and may play a role as a cellular gasotransmitter. We evaluated whether H₂S levels in serum or sputum could represent a new biomarker of COPD in a cross-sectional study. METHODS: H₂S 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 H₂S levels in AE-COPD subjects were higher than those in S-COPD, healthy smoking and non-smoking subjects (p<0.001), but serum H₂S levels in AE-COPD were lower than those in S-COPD (p<0.001). Thus, the sputum-to-serum ratio of H₂S (H₂S 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 H₂S ratios were measured during and after an exacerbation, the mean ratio was increased during exacerbation (p<0.05). H₂S 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 (%), FEV₁%predicted and FEV₁/FVC (p<0.01). The cut-off level of H₂S 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 H₂S may provide a useful marker of COPD indicative of obstructive neutrophilic inflammation and of potential ongoing exacerbation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.