Fetal Tracheal Occlusion Increases Lung Basal Cells via Increased Yap Signaling.

Vincent Serapiglia,Brian M Varisco,Jose L Peiro,Chad A Stephens,Marc Oria,Rashika Joshi,Emrah Aydin,Mario Marotta

doi:10.3389/fped.2021.780166

Abstract

Fetal endoscopic tracheal occlusion (FETO) is an emerging surgical therapy for congenital diaphragmatic hernia (CDH). Ovine and rabbit data suggested altered lung epithelial cell populations after tracheal occlusion (TO) with transcriptomic signatures implicating basal cells. To test this hypothesis, we deconvolved mRNA sequencing (mRNA-seq) data and used quantitative image analysis in fetal rabbit lung TO, which had increased basal cells and reduced ciliated cells after TO. In a fetal mouse TO model, flow cytometry showed increased basal cells, and immunohistochemistry demonstrated basal cell extension to subpleural airways. Nuclear Yap, a known regulator of basal cell fate, was increased in TO lung, and Yap ablation on the lung epithelium abrogated TO-mediated basal cell expansion. mRNA-seq of TO lung showed increased activity of downstream Yap genes. Human lung specimens with congenital and fetal tracheal occlusion had clusters of subpleural basal cells that were not present in the control. TO increases lung epithelial cell nuclear Yap, leading to basal cell expansion.

Highlights

Congenital diaphragmatic hernia (CDH) results from the failed fusion of the pleuroperitoneal folds in the 6th to the 8th week of gestation in humans and occurs in 1:2,000 births [1]
Normalizing the FKPM values of fetal rabbits undergoing fetal creation of diaphragmatic hernia (CDH), Fetal endoscopic tracheal occlusion (FETO), or both (CDH/FETO) to control, we identified increased relative expressions of basal cell-specific messenger RNAs (mRNAs) and decreased relative expressions of club, ciliated, and goblet cell mRNAs in FETO and congenital diaphragmatic hernia (CDH)/FETO lungs
While the role of Yes-associated protein (Yap) in specifying lung epithelial cell populations is well established, this study is the first to show its relevance in human lung development

Summary

Introduction

Congenital diaphragmatic hernia (CDH) results from the failed fusion of the pleuroperitoneal folds in the 6th to the 8th week of gestation in humans and occurs in 1:2,000 births [1]. The most severe defects account for 20–35% of all CDH and have 50% mortality with severe respiratory morbidity in survivors [2] For this reason, a fetal surgical technique has been developed to improve fetal lung growth in CDH. Fetal endoscopic tracheal occlusion (FETO) was first described in animal models of CDH by Harrison et al [3], and human clinical trials have been ongoing for 35 years [1]. A barrier to understanding the mechanistic underpinning of changes in CDH and TO has been the lack of a mouse TO model with high fetal survival rates This obstacle has been recently overcome with the development of a transuterine mouse TO model [12, 13]

Objectives

Methods

Results

Conclusion