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Original article
Sputum-to-serum hydrogen sulfide ratio in COPD
  1. Junpei Saito1,2,3,
  2. Alex J Mackay4,
  3. Christos Rossios1,2,
  4. David Gibeon1,2,
  5. Patricia Macedo1,2,
  6. Rudy Sinharay1,2,
  7. Pankaj K Bhavsar1,
  8. Jadwiga A Wedzicha3,
  9. Kian Fan Chung1,2
  1. 1Section of Experimental Studies, National Heart and Lung Institute, Imperial College London, London, UK
  2. 2NIHR Respiratory Biomedical Research Unit at the Royal Brompton NHS Foundation Trust and Imperial College London, London, UK
  3. 3Department of Pulmonary Medicine, Fukushima Medical University, Fukushima, Japan
  4. 4Centre for Respiratory Medicine, University College London Medical School, Royal Free Campus, London, UK
  1. Correspondence to Professor K F Chung, Experimental Studies, National Heart and Lung Institute, Imperial College London, Dovehouse St, London SW3 6LY, UK; f.chung{at}imperial.ac.uk

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.

  • COPD Exacerbations

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