Obacunone alleviates ferroptosis during lipopolysaccharide-induced acute lung injury by upregulating Nrf2-dependent antioxidant responses

Abstract

Background Acute lung injury (ALI) has received considerable attention in the field of intensive care as it is associated with a high mortality rate. Obacunone (OB), widely found in citrus fruits, is a natural bioactive compound with anti-inflammatory and antioxidant activities. However, it is not clear whether OB protects against lipopolysaccharide (LPS)-induced ALI. Therefore, in this study, we aimed to evaluate the protective effects of OB and the potential mechanisms against LPS-induced ALI and BEAS-2B cell injury. Methods We established a model of BEAS-2B cell injury and a mouse model of ALI by treating with LPS. Samples of in vitro model were subjected to cell death, Cell Counting Kit-8, and lactate dehydrogenase (LDH) release assays. The total number of cells and neutrophils, protein content, and levels of IL-6, TNF-α, and IL-1β were determined in bronchoalveolar lavage fluid (BALF). Glutathione, reactive oxygen species, and malondialdehyde levels were determined in lung tissue. Additionally, immunohistochemical analysis, immunofluorescence, western blot, quantitative real-time PCR, and enzyme-linked immunosorbent assay were conducted to examine the effects of OB. Furthermore, mice were treated with an Nrf2 inhibitor (ML385) to verify its role in ferroptosis. Data were analyzed using one-way analysis of variance or paired t-tests. Results Compared with the LPS group, OB effectively alleviated LPS-induced ALI by decreasing lung wet/dry weight ratio, reactive oxygen species and malondialdehyde production, and superoxide dismutase and glutathione consumption in vivo. In addition, OB significantly alleviated lung histopathological injury, reduced inflammatory cytokine secretion and Fe2+ and 4-HNE levels, and upregulated GPX4, SLC7A11, and Nrf2 expression. Mechanistically, OB activated Nrf2 by inhibiting Nrf2 ubiquitinated proteasome degradation. ML385 reversed the protective effects of OB against LPS-induced ALI. Conclusion Overall, OB alleviates LPS-induced ALI, making it a potential novel protective agent against LPS-induced ALI.

The protective effect of natural medicines against excessive inflammation and oxidative stress in acute lung injury by regulating the Nrf2 signaling pathway

“…Studies have demonstrated that natural pharmaceutical ingredients such as panaxydol and obacunone inhibit ferroptosis by activating the Nrf2/HO-1 pathway, thereby alleviating ALI. These findings reveal that natural medicine components inhibit ferroptosis by activating the Nrf2/HO-1 pathway, thus alleviating ALI ( Li et al, 2021 ; Li et al, 2022 ). These findings also provide a direction for the study of natural medicines for treating ALI caused by IIR and seawater drowning ( Table 1 ).…”

“…Recently, several studies have shown that ferroptosis is a type of regulatory necrosis that is more immunogenic than apoptosis and exacerbates the inflammatory response of ALI. Moreover, studies have demonstrated that panaxydol and obacunone inhibit lung injury caused ferroptosis through the activation of the Nrf2/HO-1 pathway, and inhibition of the production of inflammatory factors TNF-α, IL-1β, and IL-6 in the lungs ( Li et al, 2021 ; Li et al, 2022 ). Therefore, the Nrf2 pathway activated by various types of natural medicines is involved in the prevention and treatment of septic ALI ( Table 1 ).…”

“…When ALI occurs, the activated Nrf2 signaling pathway inhibits the activation of the NF-κB inflammatory pathway and NLRP3 inflammasome and the expression of TNF-α, IL-6, IL-1β, TGF-β, and other inflammatory factors, therefore reducing the inflammatory response. In addition, Nrf2 regulates mitochondrial membrane potential, endoplasmic reticulum stress, ferroptosis, and the activity of multiple oxidases by crosslinking of many signaling pathways ( Cullinan et al, 2003 ; Huang et al, 2020 ; Tang et al, 2021a ; Li et al, 2021 ; Li et al, 2022 ). This stabilizes mitochondrial function and autophagy and inhibits severe inflammatory reactions and excessive production of ROS (vital in the prevention and treatment of ALI).…”

Ferroptosis and Its Role in Chronic Diseases

“…Sevoflurane reduces LPS-induced ALI by repressing ferroptosis via the upregulation of HO-1 expression [205]. Obacunone reduces LPS-induced ALI by suppressing ferroptosis via the increase of Nrf2dependent antioxidant responses [206]. Hydrogen sulfide reduces ferroptosis and activates autophagy by downregulating mTOR signaling in sepsis-induced ALI [207].…”

Mechanism of ferroptosis in traditional chinese medicine for clinical treatment: A review

“…Ferroptosis plays an important role in many physiological and pathological processes, including development, aging, and immunity ( Stockwell, 2022 ). Ferroptosis is inseparable from the occurrence and development of various diseases, including cardiovascular diseases, neurological degenerative diseases, cancers, ischemic organ injuries, endocrine diseases, and respiratory diseases ( Hu et al, 2019 ; Li et al, 2022a ; Fang et al, 2022 ; Lin et al, 2022 ; Qu et al, 2022 ; Stancic et al, 2022 ; Zhang and Li, 2022 ). Iron accumulation, phospholipid peroxidation, and amino acid, lipid, and sugar metabolism are the most important components of ferroptosis ( Jiang et al, 2021 ).…”