Fortunellin attenuates sepsis-induced acute kidney injury by inhibiting inflammation and ferroptosis via the TLR4/NF-κB pathway

Abstract

Objective. To investigate the potential protective effect of fortunellin in sepsis-induced acute kidney injury (AKI) and its underlying mechanisms. Methods. Lipopolysaccharide (LPS)-treated human kidney proximal tubular epithelial (HK-2) cells were used as a cell model and sepsis-induced AKI was induced by cecal ligation and puncture (CLP) surgery in mice. Cell Counting Kit-8 (CCK8) assays and flow cytometry analysis were performed to examine the viability of HK-2 cells. Enzyme-linked immunosorbent assay (ELISA) was performed to investigate the content of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β) in vivo and in vitro. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and free iron (Fe2+) were measured as indicators of ferroptosis. The phosphorylation levels of Interleukin-1 Receptor-Associated Kinase 4 (p-IRAK4), p65 (p-65), and inhibitor of kappa B alpha (p-IκBα) were detected by western blot as an indication of nuclear factor kappa-B (NF-κB) pathway activation. Results. Our cell and animal experiments revealed that fortunellin exhibits significant anti-inflammatory and cytoprotective properties. Fortunellin counteracted LPS-induced cellular damage in HK-2 cells, enhancing cell survival and suppressing the secretion of pro-inflammatory cytokines. Additionally, fortunellin demonstrated potent antioxidant effects, reducing MDA and Fe2+ levels while increasing SOD activity and GSH content. The protective effect of fortunellin was further corroborated in the mouse model of sepsis-induced AKI. Notably, fortunellin suppressed activation of the TLR4/NF-κB pathway in the AKI model, as evidenced by decreased levels of p-p65 and p-IκBα proteins. Conclusion. Fortunellin ameliorates inflammation and oxidative stress in sepsis-induced AKI, possibly through the modulation of the TLR4/NF-κB pathway. These findings suggest fortunellin's potential as a therapeutic agent for sepsis-associated AKI.