Dexmedetomidine Mitigates Sepsis-Associated Lung Injury by Suppressing Macrophage Ferroptosis via the Nrf2/HO-1 Signaling Pathway.

Background

To investigate the protective role of dexmedetomidine (DEX) in sepsis-associated acute lung injury through the regulation of macrophage ferroptosis.

Methods

In silico screening of GeneCards and FerrDb Vv3 databases was performed to identify ferroptosis-related candidate genes modulated by dexmedetomidineDEX, lung injury, and macrophage activity, prioritizing nuclear factor erythroid 2-related factor 2 (Nrf2)/Nfe2l2 for subsequent experimental validation. A murine cecal ligation and puncture model of acute lung injury (ALI) and lipopolysaccharide-stimulated macrophages were established and subjected to treatment with DEX and/or the Nrf2 inhibitor ML385. Glutathione peroxidase 4 (GPX4), Nrf2, and heme oxygenase-1 (HO-1) protein levels were analyzed using western blotting. Ferroptosis and oxidative stress markers (superoxide dismutase [SOD], glutathione [GSH], iron content, reactive oxygen species [ROS], malondialdehyde [MDA]) were measured. Samples of fresh lung tissue were observed by electron microscopy. Macrophage phenotypes and tumor necrosis factor alpha (TNF-α) expression were assessed. Macrophage-conditioned medium was used to culture non-small cell adenocarcinoma epithelial cells (A549), and cell migration was evaluated. Proliferation-related proteins (matrix metalloprotease 9 [MMP-9] and Snail-1), key tight junction proteins (zonula occludens-1 [ZO-1] and occludin) and the apoptotic status were also analyzed.

Results

DEX significantly reduced ROS, iron content, and MDA levels while concomitantly increasing SOD activity and GSH content in both ALI model mice and LPS-treated macrophages. DEX inhibited pro-inflammatory M1 macrophage polarization with a concomitant decrease in TNF-α release through Nrf2-dependent mechanisms. DEX was found to mitigate inflammatory microenvironment-induced macrophage ferroptosis through activation of Nrf2 signaling, thereby reducing damage in A549 cells. This effect may be linked to the regulation of macrophage inflammatory phenotypes.

Conclusions

DEX improved sepsis-associated ALI by inhibiting macrophage ferroptosis and polarization toward the M1 type by activation of the Nrf2/HO-1 pathway.