title: Sputum-to-serum hydrogen sulfide ratio in COPD.
abstract: OBJECTIVE
  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.
authors.affiliation: 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.
authors.forename: Junpei
authors.initials: J
authors.lastname: Saito
authors.affiliation: Centre for Respiratory Medicine, University College London Medical School, Royal Free Campus, London, UK.
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Mackay
authors.affiliation: 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.
authors.forename: Christos
authors.initials: C
authors.lastname: Rossios
authors.affiliation: 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.
authors.forename: David
authors.initials: D
authors.lastname: Gibeon
authors.affiliation: 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.
authors.forename: Patricia
authors.initials: P
authors.lastname: Macedo
authors.affiliation: 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.
authors.forename: Rudy
authors.initials: R
authors.lastname: Sinharay
authors.affiliation: Section of Experimental Studies, National Heart and Lung Institute, Imperial College London, London, UK.
authors.forename: Pankaj K
authors.initials: PK
authors.lastname: Bhavsar
authors.affiliation: Department of Pulmonary Medicine, Fukushima Medical University, Fukushima, Japan.
authors.forename: Jadwiga A
authors.initials: JA
authors.lastname: Wedzicha
authors.affiliation: 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.
authors.forename: Kian Fan
authors.initials: KF
authors.lastname: Chung
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006862:Hydrogen Sulfide / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000378:metabolism; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000503:physiopathology; D012720:Severity of Illness Index; D013183:Sputum / Q000737:chemistry* / Q000166:cytology
chemical_list: D015415:Biomarkers; D006862:Hydrogen Sulfide
keywords: COPD Exacerbations