Protective role of zingerone against high glucose-Induced retinal pigment epithelial cell damage through modulation of the TRPM2 channel pathway

Abstract

BackgroundDiabetic retinopathy (DRP) is a leading cause of vision loss associated with chronic hyperglycemia-induced oxidative stress (OS), inflammation, and mitochondrial dysfunction in retinal pigment epithelium (RPE) cells. Zingerone (ZGN), a phenolic compound derived from Zingiber officinale, exhibits potent antioxidant and anti-inflammatory properties; however, its molecular targets in diabetic retinal damage remain unclear.MethodsThis study investigated the protective effects of ZGN against high glucose (HG)-induced cytotoxicity in human ARPE-19 cells, focusing on the ROS/PARP-1/TRPM2 signaling pathway. The cells were exposed to HG (30 mM) and treated with ZGN (0-80 mu M) for 24 h.ResultsHG incubation significantly increased MDA, PARP-1, ROS, intracellular calcium ion ([Ca-2(+)]i), and pro-inflammatory cytokines (IL-1 beta and TNF-alpha) in ARPE-19 cells, while decreasing GSH levels and cell viability. ZGN significantly restored OS, reduced cytokine release, [Ca-2(+)]i, and preserved mitochondrial membrane potential. Western blot and fluorescence analyses showed that ZGN reduced TRPM2 protein expression and suppressed [Ca-2(+)]i overload. Moreover, pharmacological inhibition of TRPM2 with 2-APB and of PARP-1 with DPQ enhanced the cytoprotective effects of ZGN, confirming that the ROS/PARP-1/TRPM2 axis mediates HG-induced oxidative damage.ConclusionsThese findings suggest that ZGN protects ARPE-19 cells by integrating OS with [Ca-2(+)]i homeostasis, providing a mechanistic rationale for its potential therapeutic use in preventing OS-related retinal damage in DRP.Graphical AbstractHigh glucose (HG) exposure triggers excessive production of reactive oxygen species (ROS) in retinal pigment epithelial (ARPE-19) cells, leading to oxidative stress (OS), inflammation, mitochondrial depolarisation, and subsequent cell death. The overproduction of ROS activates poly (ADP-ribose) polymerase-1 (PARP-1), generating ADP-ribose (ADPR) and thereby stimulating the TRPM2 channel to promote Ca-2(+) influx. Elevated intracellular Ca-2(+) further disrupts mitochondrial homeostasis, amplifies ROS accumulation, and initiates apoptotic signaling cascades. Consequently, OS depletes cellular antioxidant defences (GSH) while increasing lipid peroxidation (MDA) and pro-inflammatory cytokines (IL-1 beta and TNF-alpha). ZGN interrupts this vicious cycle through its potent antioxidant and anti-inflammatory actions, enhancing GSH levels, scavenging ROS, suppressing MDA, IL-1 beta, and TNF-alpha production, and preventing TRPM2-mediated Ca-2(+) overload. By restoring OS, reducing inflammatory mediators, and preserving mitochondrial integrity, ZGN effectively prevents HG-induced apoptosis and cell death, underscoring its therapeutic potential against OS-associated retinal injury.