Exogenous hydrogen sulfide and NOX2 inhibition mitigate ferroptosis in pressure-induced retinal ganglion cell damage

Glaucoma, a leading cause of irreversible blindness worldwide, is characterized by the progressive degeneration of retinal ganglion cells (RGCs). While elevated intraocular pressure (IOP) significantly contributes to disease progression, managing IOP alone does not completely halt it. The mechanisms underlying RGCs loss in glaucoma remain unclear, but ferroptosis-an iron-dependent form of oxidative cell death-has been implicated, particularly in IOP-induced RGCs loss. There is an urgent need for neuroprotective treatments. Our previous research showed that hydrogen sulfide (H₂S) protects RGCs against glaucomatous injury. This study aims to investigate the interplay between elevated pressure, mitochondrial dysfunction, iron homeostasis, and ferroptosis in RGCs death, focusing on how H₂S may mitigate pressure-induced ferroptosis and protect RGCs. We demonstrate alterations in iron metabolism and mitochondrial function in a subacute IOP elevation model in vivo. In vitro, we confirm that elevated pressure, iron overload, and mitochondrial dysfunction lead to RGCs loss, increased retinal ferrous iron and total iron content, and heightened reactive oxygen species (ROS). Notably, pressure increases NADPH oxidase 2 (NOX2) and decreases glutathione peroxidase 4 (GPX4), a key regulator of ferroptosis. NOX2 deletion or inhibition by H₂S prevents pressure-induced RGCs loss and ferroptosis. Our findings reveal that H₂S chelates iron, regulates iron metabolism, reduces oxidative stress, and mitigates ferroptosis, positioning slow-releasing H₂S donors are positioning as a promising multi-target therapy for glaucoma, with NOX2 emerging as a key regulator of ferroptosis.