Baicalin Alleviates Acute Lung Injury by Activating the SIRT3/GPX4 Pathway to Inhibit Lung Epithelial Cell Ferroptosis.

Abstract

Objective: This study was carried out with the objective of investigating the effect of baicalin (BA) on ferroptosis in acute lung injury (ALI) and elucidating BA's underlying mechanism during this process.

Methods: ALI was induced in mice with lipopolysaccharide (LPS), and BA was subsequently administered once daily for seven consecutive days. Lung injury severity was assessed via the lung wet-to-dry weight ratio (W/D ratio) calculation. Enzyme-linked immunosorbent assay (ELISA) was employed for determining inflammatory factor levels in bronchoalveolar lavage fluid (BALF). Histopathological lung tissue variations were examined through hematoxylin-eosin (HE) staining. Myeloperoxidase (MPO) activity was also evaluated in lung tissues. In vitro, ALI was simulated via the exposure of BEAS-2B to LPS for 24 h before BA treatment. The ferroptosis agonist Erastin or Sirtuin 3 (SIRT3) inhibitor 3-TYP were administered to cells for 1 h. CCK-8 assay and flow cytometry were respectively adopted for assessing cell survival and death. Ferroptosis-linked markers, like reactive oxygen species (ROS), malondialdehyde (MDA), reduced glutathione (GSH), as well as ferrous iron (Fe²⁺), were respectively quantified, along with the protein expression of glutathione peroxidase 4 (GPX4). SIRT3 protein expression was analyzed through Western blot (WB).

Results: Animal experiments showed that BA notably lowered the lung injury score (LIS), W/D ratio, MPO activity in lung tissue, and IL-1β, IL-6, and TNF-α levels in BALF (P<0.05). Moreover, BA lowered ROS, MDA, and Fe²⁺ levels in lung tissue (P<0.01), and elevated GSH content and the expression of GPX4 and SIRT3 (P<0.01). Similarly, in vitro experiments further confirmed that BA attenuated LPS-induced cellular injury and ferroptosis in BEAS-2B cells. However, Erastin and 3-TYP markedly reduced BA's ability to protect BEAS-2B cells from LPS-induced ferroptosis.

Conclusion: BA ameliorates LPS-triggered ALI through ferroptosis suppression in lung epithelial cells via the SIRT3/GPX4 pathway.