Rhapontigenin Alleviates Sepsis‐Associated Acute Kidney Injury and Is Accompanied by Modulation of Ferroptosis, Inflammation, and NF‐κB Signaling

Abstract

ABSTRACT Sepsis‐associated acute kidney injury (SA‐AKI) is a common complication in critically ill patients and is associated with high mortality. Evidence suggests that ferroptosis‐related lipid peroxidation and inflammatory responses contribute to renal injury. The potential effects of rhapontigenin (Rha), a natural compound with antioxidant and anti‐inflammatory properties, have not been directly examined in SA‐AKI. HK‐2 cells were pretreated with Rha for 3 h, followed by stimulation with 10 ng/mL LPS for 24 h to establish an in vitro sepsis‐associated injury model. Cell viability was assessed by CCK‐8. Ferroptosis‐related changes were evaluated by measuring GPX4 and xCT expression, intracellular Fe2+, ROS, MDA, and BODIPY‐C11‐detected lipid ROS. Erastin and ferrostatin‐1 (Fer‐1) were used for pharmacological intervention. Inflammatory cytokines (IL‐1β, IL‐6, and TNF‐α) were quantified by ELISA. NF‐κB activation was assessed by the p‐NF‐κB/NF‐κB and p‐IκBα/IκBα ratios and p65 nuclear localization, with RANKL used as an NF‐κB activator. In vivo, male C57BL/6J mice underwent cecal ligation and puncture (CLP) to induce SA‐AKI. The effects of Rha on kidney histology, renal injury markers, ferroptosis‐related indices, inflammatory cytokines, and NF‐κB signaling were evaluated. The IC50 of Rha was not reached within the tested concentration range of 0–80 μM. Rha at 5–40 μM did not significantly affect basal HK‐2 cell viability, whereas 80 μM caused a slight decrease. Rha treatment at 20 and 40 μM increased cell viability, decreased intracellular Fe2+, ROS, MDA, and lipid ROS levels, and increased GPX4 and xCT expression in LPS‐treated HK‐2 cells. Rha also reduced erastin‐induced Fe2+ accumulation, while Fer‐1 decreased Fe2+ and ROS levels and increased GPX4 and xCT expression in LPS‐treated cells. In addition, Rha lowered IL‐1β, IL‐6, and TNF‐α levels and reduced NF‐κB phosphorylation and p65 nuclear localization. RANKL partially reversed the effects of Rha on p65 nuclear localization, cell viability, Fe2+ accumulation, ROS production, and inflammatory cytokine levels. In CLP mice, Rha at 25 and 50 mg/kg reduced serum NGAL, KIM‐1, Scr, and BUN levels and decreased renal Fe2+, MDA, and inflammatory cytokine levels. The kidney injury score was significantly reduced at 50 mg/kg. Rha alleviated experimental SA‐AKI, accompanied by reductions in ferroptosis‐related changes, inflammatory responses, and NF‐κB activation. Rha attenuates SA‐AKI. In LPS‐stimulated HK‐2 cells and CLP mice, Rha improved cell viability and reduced ferroptosis‐related changes, inflammatory responses, and NF‐κB activation. graphical