Elevated metal concentrations in the CF airway correlate with cellular injury and disease severity

BackgroundBio-active trace metals have been identified in respiratory tract secretions of subjects with lung disease and may potentially influence bacterial virulence, inflammation and disease severity. We measured a diverse range of metal ions in sputum samples from subjects with CF and non-CF bronchiectasis (NCFB) compared to healthy controls and examined their relationship to airway inflammation, disease severity and the presence of bacterial pathogens.MethodsWe studied 45 subjects with CF, 8 with NCFB and 8 healthy controls. Metal concentrations were measured in sputum supernatant by inductively-coupled plasma mass spectrometry and correlated with sputum inflammatory cell counts, lactate dehydrogenase (LDH) and interleukin (IL)-8 concentrations, atmospheric particulate matter, lung function, clinical status and participant demographics.ResultsSputum from subjects with CF and NCFB contained increased concentrations of magnesium, calcium, iron and zinc. Metal ion concentrations correlated positively with LDH levels. The concentrations of magnesium, iron and zinc positively correlated with IL-8. A sub-group of CF subjects with severe lung disease demonstrated increased sputum molybdenum concentrations.ConclusionElevated concentrations of sputum metal ions appear to be associated with cell/tissue necrosis and inflammation in subjects with CF and NCFB. Sputum molybdenum concentrations may be a biomarker of severe CF airway disease.