Sequential analysis of surfactant, lung function and inflammation in cystic fibrosis patients

Background: In a cross-sectional analysis of cystic fibrosis (CF)
patients with mild lung disease, reduced surfactant activity was
correlated to increased neutrophilic airway inflammation, but not
to lung function. So far, longitudinal measurements of surfactant
function in CF patients are lacking and it remains unclear how
these alterations relate to the progression of airway inflammation
as well as decline in pulmonary function over time. Methods: As
part of the BEAT trial, a longitudinal study to assess the course
of airway inflammation in CF, we studied lung function, surfactant
function and endobronchial inflammation using bronchoalveolar
lavage fluid from 20 CF patients with normal pulmonary function (
median FEV1 94% of predicted) at three times over a three year
period. Results: There was a progressive loss of surfactant
function, assessed as minimal surface tension. The decline in
surfactant function was negatively correlated to an increase in
neutrophilic inflammation and a decrease in lung function, assessed
by FEV1, MEF75/25%VC, and MEF25%VC. The concentrations of the
surfactant specific proteins A, C and D did not change, whereas
SP-B increased during this time period. Conclusion: Our findings
suggest a link between loss of surfactant function driven by
progressive airway inflammation and loss of small airway function
in CF patients with limited lung disease.