Recombinant human
deoxyribonuclease (
rhDNase) has been demonstrated to reduce in vitro the viscosity and to improve the transport capacity of purulent respiratory mucus in
cystic fibrosis. During episodes of exacerbation of
chronic bronchitis, the patients generally expectorate purulent mucus. Purulence of mucus is associated with an increased deoxyriboneucleic
acid (
DNA) concentration. We analyzed in vitro the potential effect of
rhDNase on
chronic bronchitis mucus transport by the ciliary activity (frog palate model) and by simulated
cough (
cough machine model), as well as the effect on mucus viscosity (controlled stress rheometer) and surface properties (contact angle). Purulent sputa collected from patients with
chronic bronchitis (n = 15) during an episode of exacerbation were incubated for 30 min at 37 degrees C with either
rhDNase at two different concentrations (final concentration 2 or 4 micrograms.mL-1) or placebo. The median mucociliary transport rate was significantly improved by
rhDNase from 0.68 with placebo to 0.79 and 0.83 with 2 and 4 micrograms.mL-1 of
rhDNase, respectively. A significant improvement in mucus
cough transport was also induced by
rhDNase from 25.5 mm with placebo to 27.0 mm with either 2 or 4 micrograms.mL-1
rhDNase. These improvements in mucus transport capacity were associated with alterations in the physical properties of the mucus. The mucus median control viscosity (511.4 Pa.s) and median contact angle (0.85 rd) significantly decreased to 112.5 Pa.s and 0.74 rd, respectively, in the presence of 4 micrograms.mL-1 of
rhDNase. These findings demonstrate that recombinant
deoxyribonuclease may exert a beneficial effect on mucus clearance in vitro by altering the viscosity and surface properties of the purulent chronic bronchitic sputum samples.