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

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.