title: Transient hypoxia leads to increased serum levels of heat shock protein-27, -70 and caspase-cleaved cytokeratin 18.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) is a worldwide burden. We have previously shown that elevated levels of heat shock protein-27 (HSP27), -70 (HSP70), and caspase-cleaved cytokeratin 18 (ccCK-18) were found in serum of COPD patients correlating with disease severity. We hypothesized that transient hypoxia triggers the release of HSPs and ccCK-18.
  
  
  METHODS
  Fourteen healthy volunteers were subjected to transient normobaric hypoxia in an air-conditioned hypoxia chamber simulating an oxygen concentration at an altitude of up to 5500 meters. Serum samples were evaluated for HSP27, -70, and ccCK-18.
  
  
  RESULTS
  Baseline concentrations were 2760 pg/mL +/- 517 SEM for HSP-27, 49 pg/mL +/- 22 SEM for HSP-70, and 226 U/L +/- 20 SEM for ccCK-18. After eight hours and an altitude equivalent of 5500 meters a significant increase was recorded, depicted by serum levels of 3737 pg/mL +/- 571 SEM for HSP-27, 202 pg/mL +/- 81 SEM for HSP-70, and 244 U/L +/- 20 SEM for ccCK-18 (p < 0.05).
  
  
  CONCLUSIONS
  These results provide an explanation for the elevated serum levels of HSP-27, HSP-70, and ccCK-18 found in COPD patients, indicating that hypoxic conditions can trigger the release of the aforementioned factors.
authors.forename: Michael
authors.initials: M
authors.lastname: Lichtenauer
authors.forename: Matthias
authors.initials: M
authors.lastname: Zimmermann
authors.forename: Stefanie
authors.initials: S
authors.lastname: Nickl
authors.forename: Alexander
authors.initials: A
authors.lastname: Lauten
authors.forename: Bjoern
authors.initials: B
authors.lastname: Goebel
authors.forename: Rudin
authors.initials: R
authors.lastname: Pistulli
authors.forename: Atilla
authors.initials: A
authors.lastname: Yilmaz
authors.forename: Hans-Reiner
authors.initials: HR
authors.lastname: Figulla
authors.forename: Hendrik Jan
authors.initials: HJ
authors.lastname: Ankersmit
authors.forename: Christian
authors.initials: C
authors.lastname: Jung
mesh_terms: D000328:Adult; D000531:Altitude; D005260:Female; D050957:HSP110 Heat-Shock Proteins / Q000097:blood*; D055551:HSP27 Heat-Shock Proteins / Q000097:blood*; D006262:Health; D006360:Heat-Shock Proteins; D006801:Humans; D000860:Hypoxia / Q000097:blood*; D053538:Keratin-18 / Q000097:blood*; D008297:Male; D018832:Molecular Chaperones
chemical_list: D050957:HSP110 Heat-Shock Proteins; D055551:HSP27 Heat-Shock Proteins; C121993:HSPA4 protein, human; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; C488421:KRT18 protein, human; D053538:Keratin-18; D018832:Molecular Chaperones