In Vitro Inhibition of Neutrophil Elastase Activity by Inhaled Anti-Pseudomonas Antibiotics Used in Cystic Fibrosis Patients

Background. Inhaled antibiotics are commonly used in the treatment
of cystic fibrosis lung disease. A previous study suggested
neutrophil elastase activation by colistin in vitro. Here, we
investigated direct effects of the commonly used antibiotics
colistin and tobramycin on neutrophil elastase activity. Methods.
Neutrophil elastase was measured spectrophotometrically. The
antibiotics colistin and tobramycin were added in different
concentrations with or without the addition of albumin. Results.
Generally, neutrophil elastase activity was lower in the absence of
albumin compared to its presence. Both antibiotics, colistin and
tobramycin, had inhibitory effects on neutrophil elastase activity
except for high concentrations of colistin when albumin was absent.
Conclusions. Our results suggest inhibitory effects of colistin and
tobramycin in vitro. There was a clear dependency of neutrophil
elastase measurements on the presence of albumin. Clinical studies
are needed to investigate potential direct effects of inhaled
antibiotics on neutrophil elastase activity in cystic fibrosis
airways.