Lycorine ameliorates diabetic nephropathy by targeting RAGE and inhibiting the HMGB1/RAGE/NF-κB signaling axis

Abstract

Diabetic nephropathy (DN) is a major microvascular complication of diabetes and a leading cause of end-stage renal disease. Chronic inflammation plays a pivotal role in the pathogenesis of DN. Lycorine (LY), a complex tetracyclic pyrrolo[de]phenanthridine alkaloid derived from the Amaryllidaceae family, possesses notable anti-inflammatory activity, yet its therapeutic potential in DN remains insufficiently defined. We evaluated the renoprotective effects of LY both in vivo and in vitro. Streptozotocin (STZ)-induced diabetic mice were treated with LY, and renal function and histopathological alterations were assessed. In vitro, human renal tubular epithelial HK-2 cells were exposed to high glucose plus palmitic acid (HG + PA) with or without LY. RNA-seq analysis was performed to identify LY-regulated pathways. Molecular docking, surface plasmon resonance (SPR) assay, and cellular thermal shift assay (CETSA) were used to evaluate the interaction between LY and receptor for advanced glycation end products (RAGE). RAGE siRNA-mediated knockdown was further conducted to determine whether RAGE is required for the protective effects of LY. Activation of the HMGB1/RAGE/NF-κB signaling axis and associated inflammatory mediators was analyzed by Western blotting and RT-PCR. LY markedly alleviated renal injury in STZ-induced diabetic mice, as evidenced by reduced albuminuria, improved renal function, and attenuated renal fibrosis, apoptosis, oxidative stress, and inflammation. Notably, LY did not significantly alter blood glucose levels or body weight, indicating that its renoprotective effect was independent of glycemic control. In HG + PA-treated HK-2 cells, LY significantly suppressed apotosis, oxidative stress, and inflammatory cytokine expression. Mechanistically, RNA-seq analysis identified AGE-RAGE and NF-κB signaling pathways as key pathways modulated by LY. Molecular docking, SPR, and CETSA confirmed that LY directly interacted with RAGE. Moreover, RAGE knockdown largely abolished the additional protective effects of LY, supporting RAGE as a critical molecular target. LY inhibited HMGB1/RAGE-mediated NF-κB activation, as reflected by reduced HMGB1, RAGE, p-p65, and p-IκBα levels. LY ameliorates diabetic nephropathy without affecting blood glucose levels by directly targeting RAGE and suppressing the HMGB1/RAGE/NF-κB signaling axis. These findings identify LY as a potential RAGE-targeting therapeutic candidate for inflammation-driven diabetic kidney injury.