title: Surfactant Protein A in Exhaled Endogenous Particles Is Decreased in Chronic Obstructive Pulmonary Disease (COPD) Patients: A Pilot Study.
abstract: BACKGROUND
  Exhaled, endogenous particles are formed from the epithelial lining fluid in small airways, where surfactant protein A (SP-A) plays an important role in pulmonary host defense. Based on the knowledge that chronic obstructive pulmonary disease (COPD) starts in the small airway epithelium, we hypothesized that chronic inflammation modulates peripheral exhaled particle SP-A and albumin levels. The main objective of this explorative study was to compare the SP-A and albumin contents in exhaled particles from patients with COPD and healthy subjects and to determine exhaled particle number concentrations.
  
  
  METHODS
  Patients with stable COPD ranging from moderate to very severe (n = 13), and healthy non-smoking subjects (n = 12) were studied. Subjects performed repeated breath maneuvers allowing for airway closure and re-opening, and exhaled particles were optically counted and collected on a membrane using the novel PExA® instrument setup. Immunoassays were used to quantify SP-A and albumin.
  
  
  RESULTS
  COPD patients exhibited significantly lower SP-A mass content of the exhaled particles (2.7 vs. 3.9 weight percent, p = 0.036) and lower particle number concentration (p<0.0001) than healthy subjects. Albumin mass contents were similar for both groups.
  
  
  CONCLUSIONS
  Decreased levels of SP-A may lead to impaired host defense functions of surfactant in the airways, contributing to increased susceptibility to COPD exacerbations. SP-A in exhaled particles from small airways may represent a promising non-invasive biomarker of disease in COPD patients.
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Mona
authors.initials: M
authors.lastname: Lärstad
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Ann-Charlotte
authors.initials: AC
authors.lastname: Almstrand
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Larsson
authors.affiliation: Department of Respiratory Medicine and Allergology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Björn
authors.initials: B
authors.lastname: Bake
authors.affiliation: Department of Respiratory Medicine and Allergology, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Sven
authors.initials: S
authors.lastname: Larsson
authors.affiliation: Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Evert
authors.initials: E
authors.lastname: Ljungström
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Mirgorodskaya
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
authors.forename: Anna-Carin
authors.initials: AC
authors.lastname: Olin
mesh_terms: D000368:Aged; D000418:Albumins / Q000378:metabolism; D016022:Case-Control Studies; D003710:Demography; D045853:Exhalation; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D010865:Pilot Projects; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000503:physiopathology; D037662:Pulmonary Surfactant-Associated Protein A / Q000378:metabolism*
chemical_list: D000418:Albumins; D037662:Pulmonary Surfactant-Associated Protein A