Pulmonary epithelial cell differentiation in the nitrofen-induced congenital diaphragmatic hernia

Abstract

Background/Aim: In congenital diaphragmatic hernia (CDH), there is pulmonary neuroendocrine cell (PNEC) hyperplasia and Clara (nonendocrine) cell hypoplasia, the meaning of which remains unknown. In embryonic/fetal lung, an intricate cross talk between Notch pathway and basic helix-loop-helix transcription factors Mash 1 and Hes 1 determines the balance between endocrine and nonendocrine epithelial cell fate. Differences at the molecular level in pulmonary epithelial cell differentiation between control and CDR hypoplastic lungs were investigated.Material and Methods: The nitrofen-induced CDR rat model was used. At 15.5 days postconception (dpc), fetuses were assigned to 2 experimental groups: control and nitrofen (exposed to nitrofen, without CDR), whereas at 17.5, 19.5, and 21.5 dpc, fetuses were assigned to 3 experimental groups: control, nitrofen, and CDR (exposed to nitrofen, with CDH). The fetal lungs were processed for expression quantification of CC 10, Hes 1, Mash 1, and Dll 1 by real-time polymerase chain reaction.Results: In control fetuses, expression of all studied genes increased with gestational age. In nitrofen-exposed fetal lungs, endocrine cell marker Mash 1 was downregulated only at the earliest studied gestational age, whereas Dll 1 expression levels were significantly increased in the CDH group at 19.5 and 21.5 dpc. Regarding nonendocrine markers, Hes 1 presented increased expression at 15.5 and 19.5 dpc, whereas CC 10 was downregulated at 17.5 and 19.5 dpc but not at term.Conclusions: This study suggests that PNEC hyperplasia in CDR fetal lung is likely because of Notch signaling deregulation, whereas Clara cell hypoplasia, in CDR lungs could be a consequence of protein synthesis delay, reflecting a functional maturation hindrance and not a cell fate commitment problem.