Congenital tracheal malformation in cystic fibrosis transmembrane conductance regulator‐deficient mice

Abstract

In cystic fibrosis (CF) patients, the major alteration in pulmonary function is due to peripheral airway obstruction. In the present study, we investigated the possibility that alterations in the extrathoracic airways, particularly in the trachea that expresses high levels of CFTR (CF transmembrane conductance regulator), may contribute to respiratory dysfunction. We performed morphological analyses of the trachea and airway functional studies in adult Cftr knockout (Cftr −/− ) and F508del-CFTR mice and their controls. Macroscopic and histological examination of the trachea showed the presence of one to seven disrupted or incomplete cartilage rings in Cftr −/− mice (23/25) while only a few Cftr +/+ mice (6/25) had one abnormal ring. Tracheal defects were mainly localized in the proximal trachea. In 14 Cftr −/− mice, frontal disruption of the first three to six rings below the cricoid cartilage were associated with upper tracheal constriction. Similar tracheal abnormalities were detected in adult F508del-CFTR and in newborn Cftr −/− and F508del-CFTR mice. Tracheal and ventilatory function analyses showed in Cftr −/− mice a decreased contractile response of the proximal trachea and a reduced breathing rate due to an increase in the inspiratory and expiratory times. In F508del-CFTR mice, the expiratory time was longer than in controls. Therefore, these structural and functional abnormalities detected in adult and newborn CF mouse models may represent congenital malformations related to CFTR dysfunction. These results raise important questions concerning the mechanisms governing tracheal development within the context of CFTR protein dysfunction and the implication of such abnormalities in the pathogenesis of airway disease in CF.

Strain-Dependent Airway Hyperresponsiveness and a Chromosome 7 Locus of Elevated Lymphocyte Numbers in Cystic Fibrosis Transmembrane Conductance Regulator-Deficient Mice

“…The absence of altered lung function in B6 Cftr tm1UNC mice agrees with previous airway response phenotyping of this strain (47), although changes in breathing rate and minute volume (48,49) have been reported for B6 Cftr tm1UNC mice; therefore, lung function changes apart from airway hyperresponsiveness may exist in this strain. We are not aware of prior reports of the lung function in BALB Cftr tm1UNC mice.…”

Effect of Prenatal versus Postnatal Vitamin D Deficiency on Pulmonary Structure and Function in Mice

“…Similar findings have been shown in cystic fibrosis animal models (30). Cartilaginous thinning in vitamin D-deficient pups may be due to a reduction in vitamin D-induced deposition of proteoglycans by mature chondrocytes, as shown in cell culture data from rabbits (31).…”

Ca v 3.2 T-type calcium channel is required for the NFAT-dependent Sox9 expression in tracheal cartilage

“…We are the first, to our knowledge, to show that VGCCs are involved in the development of tracheal cartilage. Mice lacking chloride channels, cystic fibrosis transmembrane conductance regulator (CFTR) (90), or transmembrane protein 16A (TMEM16A) (7) also show abnormal tracheal cartilaginous rings; however, the tracheal cartilage defects in CFTR −/− and TMEM16A −/− mice may be secondary to defects in the tracheal epithelium (7,90). Hence, our study provides novel insight into the roles of Ca v 3.2 T-type Ca 2+ channels in tracheal development.…”