Reduction in viscoelasticity in cystic fibrosis sputum in vitro using combined treatment with nacystelyn and rhDNase

Abstract

The objective of this study was to evaluate the individual and combined effects of Nacystelyn (NAL) and rhDNase in vitro on the rheological properties of cystic fibrosis (CF) sputum. Sputum samples were collected from 11 CF patients and subjected to the following protocols: 1) negative control sample without any treatment; 2) positive control sample incubated with 0.02 ml of normal saline; 3) incubation of CF sputum with 0.02 mL DNase (25 micrograms/mL in normal saline) at 37 degrees C to achieve 2.5 micrograms/g final sputum concentration (approximately 100 nM); 4) incubation of CF sputum with 0.02 mL NAL (30.9 micrograms/mL in normal saline) at 37 degrees C to achieve 3.09 micrograms/g final sputum concentration (10 microM); and 5) combination of protocols 3 and 4 with half the concentration of each drug. The samples in protocols 2 through 5 were incubated for 30 minutes at 37 degrees C. For each protocol, spinnability by filancemeter and viscoelasticity (log G*) by magnetic microrheometer were measured at baseline and 30 minutes. Treatment of the sputum with rhDNase alone or NAL alone decreased spinnability more than control treatment with saline. Combining NAL with rhDNase at half the concentration of each drug significantly decreased spinnability more than either treatment by itself. There were no significant changes in log G* or the derivative parameters, mucociliary clearability index (MCI) and cough clearability index (CCI). The enhanced reduction in sputum spinnability by the combination of NAL and rhDNase indicates additative effects between these two mucolytic treatments. These results suggest that combined treatment with rhDNase and NAL should be considered as a potential therapy for CF patients.