Pharmacological rescue of mutant CFTR protein improves the viscoelastic properties of CF mucus

Background: In CF patients, the defective ion transport causes a simultaneous reduction of fluid, Cl- and HCO3- secretion. We aimed to demonstrate that the resulting altered properties of mucus can be recovered using lumacaftor, a CFTR corrector. Methods: The micro-rheology of non-CF and CF mucus was analysed using Multiple Particle Tracking. Results: The diffusion coefficient of nano-beads imbedded in mucus from CF human bronchial epithelium was lower than in non-CF mucus, and the elastic and viscous moduli were higher. We found that 25% correction of F508del-CFTR mutation with lumacaftor was enough to improve significantly CF mucus properties. Surprisingly, also incubation with amiloride, a compound that reduces fluid absorption but might not change the secretion of HCO3- towards the airway surface fluid, improved CF mucus properties. Conclusion: CF mucus properties can be recovered by either improving the hydration of the airways or recovering Cl- and HCO3- secretion across the mutated protein treated with a corrector compound.