Lack of Fzd6 in Ciliated Cells Suppresses Ferroptotic Alveolar Cell Death induced by LPS and Corona Virus [RNA-seq subset II]

Pulmonary inflammation compromises lung barrier function and underlies many lung diseases including acute lung injury and acute respiratory distress syndrome (ARDS). However, mechanisms by which lung cells respond to the damage caused by the inflammatory insults are not completely understood. Here we show that Fzd6-deficiency in Foxj1+ ciliated cells reduces pulmonary permeability, lipid peroxidation, and alveolar cell death accompanied with an increase in alveolar number in lungs insulted by LPS or mouse coronavirus MHV-1. Single cell RNA sequencing of lung cells indicates that the lack of Fzd6, which is primarily expressed in Foxj1+ ciliated cells, increases expression of the aldo-keto reductase Akr1b8. Intratracheal administration of the Akr1b8 protein phenocopies Fzd6-deficient lung phenotypes. In addition, ferroptosis inhibitors also phenocopy Fzd6-deficient lung phenotypes and exert no further effects in Fzd6-deficient lungs. These results indicate that Fzd6-deficiency suppresses inflammation-induced ferroptotic death of alveolar cells via the release of Akr1b8, thus revealing a previously unknown mechanism by which Fzd6 signaling regulates ferroptosis via a paracrine pathway. In addition, this study demonstrates the yet-to-be appreciated importance of ciliated cells in protecting alveolar cells during pulmonary inflammation. Compare gene expression at single cell level between TdTomato-positive cells isolated from WT and Fzd6 KO lungs after LPS treatment