RTA408 alleviates lipopolysaccharide-induced acute lung injury via inhibiting Bach1-mediated ferroptosis.

The approved traditional Asian medicine RTA408 (Omaveloxolone) has demonstrated potent anti-inflammatory properties in the treatment of Friedreich's ataxia. However, its effect on lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains poorly understood. This study aims to evaluate the effect of RTA408 on LPS-induced ALI and elucidate its underlying mechanisms. In this study, in vivo experiments demonstrated that RTA408 significantly ameliorated LPS-induced mouse ALI, characterized by reduced pathological damage and neutrophil infiltration as well as decreased lung edema of murine lung tissues. Moreover, LPS administration induced ferroptosis in ALI mice, evidenced by increased MDA levels, reduced GSH and SOD activity, and decreased expression of ferroptosis repressors (GPX4 and SLC7A11), whereas RTA408 reversed these changes. Consistently, RTA408 reduced ferroptosis and improved cell damage in LPS-stimulated MLE-12 cells, as evidenced by decreased ROS and MDA levels, increased SOD, GSH activity and ferroptosis repressors expression. Meanwhile, the protective effective of RTA408 on LPS-induced oxidative damage was blocked by ferroptosis inhibitor ferrostatin-1 (Fer-1). Mechanistic studies demonstrated that RTA408 inhibited the expression and nuclear translocation of Bach1, and the anti-ferroptosis effect was diminished by Bach1 siRNA or Bach1 knockout (Bach1-/-) mice. Furthermore, Bach1-/- mice exhibited attenuated ALI induced by LPS compared to wild-type (WT) mice, and the protective effect of RTA408 on LPS-challenged ALI was not observed in Bach1-/- mice. In conclusion, our data suggested that RTA408 alleviates LPS-induced ALI by interfering Bach1-mediated ferroptosis and might be a novel candidate for LPS-induced ALI/ARDS therapy.

Wu Y ，Zhang Y ，Ge L ，He S ，Zhang Y ，Chen D ，Nie Y ，Zhu M ，Pang Q ... -  《-》

Ferrostatin-1 alleviates lipopolysaccharide-induced acute lung injury via inhibiting ferroptosis.

Ferroptosis is a newly recognized type of cell death, which is different from traditional necrosis, apoptosis or autophagic cell death. However, the position of ferroptosis in lipopolysaccharide (LPS)-induced acute lung injury (ALI) has not been explored intensively so far. In this study, we mainly analyzed the relationship between ferroptosis and LPS-induced ALI. In this study, a human bronchial epithelial cell line, BEAS-2B, was treated with LPS and ferrostatin-1 (Fer-1, ferroptosis inhibitor). The cell viability was measured using CCK-8. Additionally, the levels of malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), and iron, as well as the protein level of SLC7A11 and GPX4, were measured in different groups. To further confirm the in vitro results, an ALI model was induced by LPS in mice, and the therapeutic action of Fer-1 and ferroptosis level in lung tissues were evaluated. The cell viability of BEAS-2B was down-regulated by LPS treatment, together with the ferroptosis markers SLC7A11 and GPX4, while the levels of MDA, 4-HNE and total iron were increased by LPS treatment in a dose-dependent manner, which could be rescued by Fer-1. The results of the in vivo experiment also indicated that Fer-1 exerted therapeutic action against LPS-induced ALI, and down-regulated the ferroptosis level in lung tissues. Our study indicated that ferroptosis has an important role in the progression of LPS-induced ALI, and ferroptosis may become a novel target in the treatment of ALI patients.

Liu P ，Feng Y ，Li H ，Chen X ，Wang G ，Xu S ，Li Y ，Zhao L ... -  《-》

Esketamine alleviates ferroptosis-mediated acute lung injury by modulating the HIF-1α/HO-1 pathway.

Alveolar epithelial cell (AEC) ferroptosis contributes to the progression of acute lung injury (ALI). Esketamine (ESK) is a new clinical sedative, anesthetic, and analgesic drug that has attracted substantial attention in mental health research because of its antidepressant effects. However, the effects of ESK on ferroptosis-mediated ALI remain unclear. This study aimed to explore the protective effect of ESK on AEC ferroptosis in ALI and its potential molecular mechanism in vivo and in vitro. The antiferroptotic and anti-inflammatory effects of ESK were assessed in a mouse model of lipopolysaccharide (LPS)-induced ALI. In vitro, the epithelial cell lines MLE-12 and A549 were used to examine the underlying mechanism by which ESK regulates inflammation and ferroptosis. ESK protected mice against LPS-induced ALI, significantly attenuated pathological changes in the lungs and decreased inflammation and ferroptosis. In vitro, ESK inhibited LPS-induced inflammation and ferroptosis in MLE-12 and A549 cells. Moreover, ferroptosis mediated inflammation in LPS-induced ALI in vivo and in vitro, and ESK decreased the LPS-induced inflammatory response by suppressing ferroptosis. ESK promoted the HIF-1α/HO-1 pathway in LPS-treated AECs and in the lung tissues of mice with LPS-induced ALI. Moreover, pretreatment with ESK and the HIF-1α stabilizer dimethyloxaloylglycine (DMOG) substantially attenuated lung injury and prevented changes in ferroptosis-related biochemical indicators, including glutathione (GSH) depletion, malondialdehyde (MDA) production and glutathione peroxidase 4 (GPX4) downregulation, in untreated LPS-induced mice but not in LPS-induced mice treated with the HO-1 inhibitor zinc protoporphyrin (ZNPP). Similar effects were observed in vitro in HO-1 siRNA-transfected A549 cells after LPS incubation but not in control siRNA-transfected cells. ESK can inhibit ferroptosis-mediated lipid peroxidation by increasing the expression of HIF-1α/HO-1 pathway, highlighting the potential of ESK to treat LPS-induced ALI.

Shi J ，Song S ，Wang Y ，Wu K ，Liang G ，Wang A ，Xu X ... -  《-》

HMGB1 inhibition blocks ferroptosis and oxidative stress to ameliorate sepsis-induced acute lung injury by activating the Nrf2 pathway.

The proinflammatory properties of high-mobility group box protein 1 (HMGB1) in sepsis have been extensively studied. This study aimed to investigate the impact of HMGB1 on ferroptosis and its molecular mechanism in sepsis-induced acute lung injury (ALI). A septic mouse model was established using the cecal ligation and puncture method. Blocking HMGB1 resulted in improved survival rates, reduced lung injury, decreased levels of ferroptosis markers (reactive oxygen species, malondialdehyde, and Fe2+), and enhanced antioxidant enzyme activities (superoxide dismutase and catalase) in septic mice. In addition, knockdown of HMGB1 reduced cellular permeability, ferroptosis markers, and raised antioxidant enzyme levels in lipopolysaccharide (LPS)-stimulated MLE-12 cells. Silencing of HMGB1 led to elevations in the expressions of ferroptosis core-regulators in LPS-treated MLE-12 cells, such as solute carrier family 7 member 11 (SLC7A11), solute carrier family 3 member A2 (SLC3A2), and glutathione peroxidase 4. Furthermore, blocking HMGB1 did not alter ferroptosis, oxidative stress-related changes, and permeability in LPS-treated MLE-12 cells that were pretreated with ferrostatin-1 (a ferroptosis inhibitor). HMGB1 inhibition also led to elevated expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream targets, heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1) in LPS-treated MLE-12 cells and lung tissues from septic mice. The Nrf2-specific inhibitor ML385 reversed the effects of HMGB1 silencing on ferroptosis and cell permeability in LPS-treated MLE-12 cells. Our findings indicated that the inhibition of HMGB1 restrains ferroptosis and oxidative stress, thereby alleviating sepsis-induced ALI through the activation of Nrf2 signaling.

Jia YJ ，Xiong S ，Yao M ，Wei Y ，He Y ... -  《-》

Deletion of BACH1 alleviates ferroptosis and protects against LPS-triggered acute lung injury by activating Nrf2/HO-1 signaling pathway.

Multiple lines of evidences have unraveled the emerging role of ferroptosis in the pathophysiological process of acute lung injury (ALI). In this study, we aimed to decipher the role of BACH1 in the onset and progression of ALI with a focus on ferroptosis and elucidated potential molecular mechanism. We observed that BACH1 expression was drastically elevated in BEAS-2B cells upon exposure to LPS. In the functional aspect, BACH1 deletion exerted an anti-inflammatory property, featured by decreased the secretion of several cytokines including TNF-α, IL-1β and IL-6 in the face of LPS challenge. What's more important, BACH1 knockout evidently repressed LPS-triggered oxidative stress damage, as evidenced by reduced reactive oxygen species (ROS) production and malondialdehyde (MDA) generation, accompanied with the elevated the activities of superoxide dismutase (SOD), GSH-Px and CAT. Meanwhile, ablation of BACH1 restrained LPS-elicited ferroptosis, as characterized by decreased iron content and PTGS2 expression, accompanied with increased expression of SLC7A11 and GPX4. In terms of mechanism, Nrf2/HO-1 signaling inhibitor effectively abrogated the beneficial effects of BACH1 inhibition on LPS-stimulated inflammation, oxidative damage and ferroptosis. Taken together, these preceding outcomes strongly illuminated that BACH1 was a novel regulator of LPS-evoked injury through regulation of inflammation response, oxidative stress and ferroptosis via activation Nrf2/HO-1 signaling, indicating that BACH1 may represent as a promising novel therapeutic candidate for ALI treatment.

Wang RX ，Gu X ，Zhang SX ，Zhao YJ ，Zhang HJ ，Li FY ... -  《-》