The researchers of this project suggest that the therapeutic effect of lumacaftor corrector of F508del-CFTR consist in an increased bicarbonate secretion and consequent improvement of CF bronchial mucus properties. Their aim is to confirm this mechanism on the airway surface epithelium by different assays involving bicarbonate secretion. Then they set up CF intestinal organoids as polarized epithelia able to secrete mucus, so that it will be possible to measure the mucus properties in this tissue before and after treatment with correctors and with bicarbonate. These informations will allow the design of more accurate clinical trials for CF patients, using inhaled bicarbonate.