Targeting Acid Sphingomyelinase-Ceramide Axis Suppresses Neuronal Ferroptosis in Ischemic Stroke: Therapeutic Potential of Desipramine

Emerging evidence indicates that ceramide levels are elevated in serum and brain tissues of ischemic stroke patients or animal models; however, the precise role of ceramide and its regulatory mechanisms in ischemic brain injury remain undefined. Using a mouse transient middle cerebral artery occlusion (ischemia/reperfusion, I/R) model and oxygen–glucose deprivation/reoxygenation (OGD/Re)-induced neuronal injury models, we demonstrated that cerebral I/R or OGD/Re injury triggered marked ceramide accumulation in neurons, predominantly mediated by acid sphingomyelinase (ASM). ASM knockdown or pharmacological inhibition with the validated inhibitor desipramine (Des) significantly reduced neuronal ceramide production. Notably, Des treatment markedly decreased cerebral infarct volume, ameliorated neurological deficits and neuronal death both in vivo and in vitro. Furthermore, Des or ASM knockdown effectively suppressed ferroptosis induced by cerebral I/R, OGD/Re, as well as by the ferroptosis inducer, RAS-selective lethal 3 (RSL3), concomitant with reduced ASM activity and ceramide levels. Conversely, exogenous ceramide supplementation enhanced ferroptosis in OGD/Re-treated neurons. Mechanistically, ceramide accumulation exacerbated mitochondrial damage and downregulated the deacetylase sirtuin 3 (Sirt3) level. Reduced mitochondrial Sirt3 activity was associated with enhanced OGD/Re-induced acetylation of glutathione peroxidase 4 (GPX4), a hallmark protein for anti-ferroptosis, and reduced total GPX4 abundance. Collectively, these findings support a proposed model in which the ASM-ceramide axis drives neuronal ferroptosis in ischemic stroke through downregulation of mitochondrial Sirt3 and the accompanying increase in GPX4 acetylation. Des exerts potent neuroprotective effects against ischemic brain injury by inhibiting ASM activity, thus providing a promising drug repurposing strategy and a novel therapeutic target for the treatment of ischemic stroke.