Airway morphogenesis in wild type and heterozygous F508del mouse embryonic lungs treated by Elexacaftor/Tezacaftor/Ivacaftor

Abstract

Background: CFTR modulators combo-therapy Elexacaftor/Tezacaftor/Ivacaftor (ETI) is efficient in cystic fibrosis patients bearing a least one F508del mutation. An increasing number of pregnancies in treated women is expected. Safety data during pregnancy are lacking.

Aims: To study the potential impact of ETI treatment on airway development in a murine model at the pseudo-glandular stage.

Methods: Branching morphogenesis and expression of Fgf10, Fgfr2IIIb, Shh, and Hhip were analysed in lung explants sampled at E12.5 from heterozygous F508del and wild-type mouse embryos after 24, 48 and 72h of culture in different conditions: standard culture medium, treatment with ETI or with Forskolin ± the inhibitor of CFTR Inh-172.

Results: After 72h of culture and in comparison to control medium, ETI induced a decrease of 78% in lung branching in heterozygous F508del lungs (p<0.0001) and of 79% in wild-type lungs (p<0.0001), and a significant increase of the percentage of terminal bud dilations, by 5.3 fold (p<0.001) for heterozygous F508del lungs and by 5.7 fold (p=0.004) in wild-type lungs. These results were recapitulated by cAMP-dependent CFTR activation by Forskolin and reversed by addition of Inh-172. ETI induced a significant decrease in Fgf10, Fgfr2IIIb, Shh and Hhip expression in lung explants of both groups treated with ETI for 72h.

Conclusion: Our results show that ETI alters lung branching morphogenesis of control and heterozygous F508del mouse embryos during the pseudo-glandular stage. Those alterations are related, at least in part, to CFTR activation. This call for caution and suggest that ETI exposure during pregnancy could interfere with airway morphogenesis.