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Updated: Dec 11, 2025
Rapid Viscoelastic Characterization of Airway Mucus Using a Benchtop Rheometer
Published on: April 21, 2022
Serine proteases degrade airway mucins in cystic fibrosis
Markus O Henke1, Gerrit John, Christina Rheineck
1Department of Pulmonary Medicine, Philipps-University Marburg, Baldingerstraße 1, 35043 Marburg, Germany. markus.henke@staff.uni-marburg.de
Abstract:
Airway mucins are the major molecular constituents of mucus. Mucus forms the first barrier to invading organisms in the airways and is an important defense mechanism of the lung. We confirm that mucin concentrations are significantly decreased in airway secretions of subjects with cystic fibrosis (CF) who have chronic Pseudomonas aeruginosa infection. In sputum from CF subjects without a history of P. aeruginosa, we found no significant difference in the mucin concentration compared to mucus from normal controls. We demonstrate that mucins can be degraded by synthetic human neutrophil elastase (HNE) and P. aeruginosa elastase B (pseudolysin) and that degradation was inhibited by serine proteases inhibitors (diisopropyl fluorophosphates [DFP], phenylmethylsulfonyl fluoride [PMSF], and 1-chloro-3-tosylamido-7-amino-2-heptanone HCl [TLCK]). The mucin concentration in airway secretions from CF subjects is similar to that for normal subjects until there is infection by P. aeruginosa, and after that, the mucin concentration decreases dramatically. This is most likely due to degradation by serine proteases. The loss of this mucin barrier may contribute to chronic airway infection in the CF airway.
Insights
Mucin concentrations decrease in cystic fibrosis (CF) airways with Pseudomonas aeruginosa infection, likely due to protease degradation. This loss of the mucin barrier may worsen chronic CF airway infections.
Area of Science:
- Pulmonary Medicine
- Microbiology
- Biochemistry
Background:
- Airway mucus, primarily composed of mucins, is a critical lung defense mechanism.
- Mucins form a protective barrier against invading pathogens in the airways.
Purpose of the Study:
- To investigate mucin concentration changes in cystic fibrosis (CF) airways.
- To determine the role of Pseudomonas aeruginosa infection and proteases in mucin degradation.
Main Methods:
- Quantified mucin concentrations in sputum from CF patients and healthy controls.
- Assessed the effect of human neutrophil elastase (HNE) and Pseudomonas aeruginosa elastase B (pseudolysin) on mucin degradation.
- Evaluated the inhibitory effects of serine protease inhibitors (DFP, PMSF, TLCK) on mucin degradation.
Main Results:
- Mucin concentrations were significantly reduced in CF patients with chronic P. aeruginosa infection.
- No significant difference in mucin concentration was observed in CF patients without P. aeruginosa infection compared to controls.
- HNE and pseudolysin degraded mucins, an effect inhibited by serine protease inhibitors.
Conclusions:
- P. aeruginosa infection leads to a dramatic decrease in airway mucin concentration in CF patients.
- Serine proteases likely degrade mucins in CF airways, contributing to the loss of the protective mucus barrier.
- Reduced mucin barrier function may facilitate chronic P. aeruginosa infection in cystic fibrosis airways.
