Functional Analysis by Dynamic Imaging of the Respiratory Epithelium in Infants With Cystic Fibrosis

Cystic fibrosis (CF) is characterized by airway inflammation and infection leading to progressive destruction of lungs. One of the most important abnormalities in CF is an abnormal processing of the mutated CFTR protein through the endoplasmic reticulum that causes abnormal location or even absence of the protein at the apical plasma membrane of airway epithelial cells. This abnormality results in a marked dehydration of the airway surface fluid, decreased mucus transport and airway obstruction. Nevertheless, the events that occur very early during the progression of the disease at the airway level in infants are not known. At cellular level, it has also been reported that the CFTR expression and localization could be related to the differentiation state of the airway epithelium. Furthermore, it has been reported that gap junctions could be involved in dysregulate inflammation process. In CF infants, many answers are still lacking. For a better understanding of the early stages of cystic fibrosis, it is of major interest to study respiratory epithelial cells obtained as early as possible. In 15 CF infants and 15 control infants, a nasal brushing will be performed by means of a soft sterile cytology brush. Samples will be used for cytological and functional studies: ciliary beating frequency, cAMP-dependent chloride efflux, potassium efflux, tight and gap junctions functionalities. These studies will be done in basal conditions and will be repeated after activation of the nasal epithelial cells by the bacteria, such as Staphylococcus aureus, which can be found very early in the course of CF disease.