Phenylephrine attenuates LPS-induced lung injury via Foxh1/GSK-3β/β-catenin-mediated alveolar epithelial cell differentiation in ARDS.

Abstract

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a hypoxemic respiratory failure caused by severe pulmonary inflammation and progressive alveolar epithelial injury, and effective treatments are currently lacking. Our previous study demonstrated that the α-adrenergic receptor (α-AR) agonist phenylephrine (PE) alleviates lipopolysaccharide (LPS)-induced lung injury in ARDS mice by suppressing alveolar macrophage inflammation. However, whether alveolar epithelial cells (AECs)-critical components of the blood-air barrier for defense-contribute to PE's lung-protective effects remained unclear. METHODS: An acute lung injury model was established by intratracheal instillation of LPS, followed by PE intervention. Lung injury was assessed using H&E staining and TUNEL staining, while inflammatory factors in lung tissue and serum were measured by ELISA. Alveolar epithelial differentiation was evaluated via immunofluorescence and Western blot. Subsequently, transcriptome sequencing was employed to identify the key regulatory protein Foxh1 involved in cell differentiation, and its downstream pathways were further investigated through Western blotting and co-immunoprecipitation assays. RESULTS: The results showed that PE significantly ameliorated lung injury in ARDS and promoted the differentiation of AECs toward alveolar type I (AT1) cells. Transcriptome sequencing revealed that PE upregulates Forkhead box protein H1 (Foxh1) in LPS-induced AECs. Mechanistically, Foxh1 enhanced β-catenin expression by inhibiting GSK-3β activity, thereby blocking LPS-induced ubiquitin-mediated degradation of β-catenin and driving AEC differentiation. CONCLUSION: In summary, PE alleviates LPS-induced lung injury in ARDS by activating the Foxh1/GSK-3β/β-catenin signaling pathway to promote the differentiation of AECs into AT1 cells.