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Sputum neutrophils are elevated in smelter workers, and systemic neutrophils are associated with rapid decline in FEV1
  1. Liv Ingunn Bjoner Sikkeland1,
  2. Helle Laier Johnsen2,
  3. Tonje Bøyum Riste3,
  4. Neil E Alexis4,
  5. Bente Halvorsen1,5,6,
  6. Vidar Søyseth1,7,
  7. Johny Kongerud1,3
  1. 1Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
  2. 2National Institute of Occupational Health, Oslo, Norway
  3. 3Department of Respiratory Medicine, Rikshospitalet, Oslo University Hospital, Oslo, Norway
  4. 4Center for Environmental Medicine, Asthma and Lung Biology, UNC Chapel Hill, Chapel Hill, North Carolina, USA
  5. 5Research Institute for Internal Medicine, Oslo University Hospital, Oslo, Norway
  6. 6 K.G. Jebsen Inflammation Research Centre, University of Oslo, Oslo, Norway
  7. 7Department of Medicine, Akershus University Hospital, Lørenskog, Norway
  1. Correspondence to Liv Ingunn Bjoner Sikkeland, Department of Respiratory Medicine, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, P.O. Box 4950 Nydalen, Oslo 0424, Norway; l.i.b.sikkeland{at}medisin.uio.no

Abstract

Objectives In a previous study on smelter workers we, found significant relationship between exposure to dust and accelerated annual decline in forced expiratory volume in 1 s (FEV1). In this cross-sectional study at the end of a follow-up, we aimed to investigate the possible association between annual decline in FEV1 and markers of airways, and systemic inflammation in smelter workers.

Methods Employees (n=76 (27 current smokers)) who had been part of a longitudinal study (9–13 years) that included spirometry (>6 measurements) and respiratory questionnaires, performed induced sputum, exhaled NO and had blood drawn. Participants with annual decline in FEV1≥45 mL were compared with participants with annual decline <45 mL; also 26 non-exposed controls were included.

Results Compared with non-exposed controls, smelter workers demonstrated a significantly increased percentage of neutrophils (mean (SD)) (57% (17) vs 31% (15)) and matrix metalloproteinases 8 (MMP-8) levels in sputum, and MMP-9, surfactant protein D (SpD) and transforming growth factor β (TGFb) levels in blood. A significant association in FEV1≥45 mL was found for blood neutrophils when controlling for smoking habits (OR=1.7 (95% CI 1.0 to 2.8), p=0.045). Airway and blood protein markers were not associated with annual decline in FEV1.

Conclusions All workers displayed airway and systemic inflammation characterised by increased levels of neutrophils and MMP-8 in sputum, and MMP-9, SpD and TGFβ in blood compared with non-exposed controls. Blood neutrophils in particular were significantly elevated in those workers with the most rapid decline in lung function. A similar observation was not seen with airway neutrophils. In the present study, we were able to identify systemic but not airway inflammatory markers that can predict increased decline in FEV1 in smelter workers.

  • Induced sputum
  • Smelter Workers
  • Work Exposure

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