title: MUC5AC and MUC5B mucins increase in cystic fibrosis airway secretions during pulmonary exacerbation.
abstract: BACKGROUND
  Cystic fibrosis (CF) is believed to be associated with mucus hypersecretion; thus, the principal airway gel-forming mucins, MUC5AC and MUC5B, are also expected to be increased relative to non-CF secretions. However, we have shown that these mucins are decreased during stable CF disease.
  
  
  OBJECTIVE
  In this study, we determine if these mucins increase during a pulmonary exacerbation of CF.
  
  
  METHODS
  Expectorated sputum was collected from 11 adults with CF during stable disease and then during a pulmonary exacerbation and from 12 healthy control subjects. MUC5AC and MUC5B proteins were measured by Western blot. DNA content was measured using microfluorimetry.
  
  
  RESULTS
  MUC5AC protein increased by 908% and MUC5B by 59% (p < 0.05 for both) during an exacerbation compared with periods of stable disease. During stable disease, the vol/vol quantity of MUC5AC protein was 89% less than normal mucus, and the mucin-associated sugars, measured using a lectin binding assay, were 46% less compared with normal mucus. The concentration of DNA in CF sputum did not increase during an exacerbation.
  
  
  CONCLUSIONS
  During a CF exacerbation, concentration of secreted mucin increased to the amount found in mucus from normal subjects, suggesting that the capacity to secrete mucin in response to an infection or inflammatory stimulus is preserved in CF airways. This might help to protect the airway from injury.
authors.affiliation: Philipps-University Marburg, Department of Pulmonary Medicine, Baldingerstrasse 1, 35043 Marburg, Germany. markus.henke@staff.uni-marburg.de.
authors.forename: Markus O
authors.initials: MO
authors.lastname: Henke
authors.forename: Gerrit
authors.initials: G
authors.lastname: John
authors.forename: Michele
authors.initials: M
authors.lastname: Germann
authors.forename: Hermann
authors.initials: H
authors.lastname: Lindemann
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Rubin
mesh_terms: D000208:Acute Disease; D000328:Adult; D016022:Case-Control Studies; D003550:Cystic Fibrosis / Q000378:metabolism*; D005541:Forced Expiratory Volume; D006801:Humans; D055271:Mucin 5AC; D055257:Mucin-5B; D009077:Mucins / Q000378:metabolism*; D013183:Sputum / Q000737:chemistry
chemical_list: C524678:MUC5AC protein, human; C524578:MUC5B protein, human; D055271:Mucin 5AC; D055257:Mucin-5B; D009077:Mucins