mitoquinone and Acute-Lung-Injury

Numerous studies demonstrated that bleomycin (BLM) caused acute lung injury (ALI). This study explored the role of mitochondrial reactive oxygen species (ROS) on BLM-induced ALI and pulmonary epithelial ferroptosis. Male C57BL/6J mice were intratracheally injected with BLM (3.0 mg/kg). BEAS-2B cells, human bronchial epithelial cells, were cultured with BLM (10 μg/ml). Pulmonary MDA and 4-HNE, two markers of lipid peroxidation, were elevated in BLM-exposed mice. Oxidized lipids were upregulated in BLM-exposed BEAS-2B cells. Ferroptosis-characteristic ultrastructure, mainly disappearance of mitochondrial bilayer membrane structure and cristae, was observed in BLM-exposed pulmonary epithelium. Ferrostatin-1, a specific inhibitor of ferroptosis, attenuated BLM-evoked pulmonary lipid peroxidation, ferroptosis-characteristic mitochondrial ultrastructure and pulmonary epithelial death. The in vitro experiments showed that mitochondrial membrane potentials (MMPs) were decreased and mitochondrial ROS were increased in BLM-exposed BEAS-2B cells. Mitoquinone (MitoQ), a mitochondria-targeted antioxidant, prevented BLM-induced MMP reduction and mitochondrial ROS elevation in BEAS-2B cells. The in vivo experiment found that MitoQ attenuated BLM-evoked GSH depletion and lipid peroxidation in mouse lungs. Moreover, MitoQ prevented BLM-induced ferroptosis-characteristic mitochondrial changes, pulmonary epithelial death and ALI. In conclusion, mitochondrial ROS are an initiator of BLM-induced pulmonary epithelial ferroptosis. Mitochondria-targeted antioxidants may be used as potential therapeutic agents for BLM-induced ALI.

Topics: Acute Lung Injury; Animals; Bleomycin; Ferroptosis; Humans; Lung; Male; Mice; Mice, Inbred C57BL; Mitochondria; Reactive Oxygen Species

Lipopolysaccharide (LPS) has been known to cause alveolar epithelial cell (AEC) apoptosis and barrier breakdown that characterize acute lung injury (ALI) and acute respiratory distress syndrome. We aimed to investigate whether mitoquinone (MitoQ), a mitochondria-targeted antioxidant, could alleviate LPS-induced AEC damage in ALI and its underlying mechanisms. In vitro studies in AEC A549 cell line, we noted that LPS could induce dynamin-related protein 1 (Drp1)-mediated mitochondrial fission, AEC apoptosis and barrier breakdown, which could be reversed with MitoQ and mitochondrial division inhibitor 1 treatment. Moreover, the protective role of MitoQ was attenuated with Drp1 overexpression. Nuclear factor E2-related factor 2 (Nrf2) downregulation could block the effect of MitoQ by decreasing the expression of Nrf2 target genes in LPS-treated AEC, such as heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase 1 (NQO1). Nrf2 gene knockdown in LPS-treated A549 cells prevented the protective effect of MitoQ from decreasing Drp1-mediated mitochondrial fission, AEC apoptosis and barrier breakdown. The lung protective effect of MitoQ by regulating the Drp1-mediated mitochondrial fission, AEC apoptosis and barrier breakdown was further confirmed in vivo with LPS-induced ALI mouse model. Additionally, the protective effect of MitoQ was inhibited by Nrf2 inhibitor ML385. We therefore conclude that MitoQ exerts ALI-protective effects by preventing Nrf2/Drp1-mediated mitochondrial fission, AEC apoptosis as well as barrier breakdown.

Topics: Acute Lung Injury; Animals; Dynamins; Lipopolysaccharides; Mice; NF-E2-Related Factor 2; Organophosphorus Compounds; Signal Transduction; Ubiquinone