Inhibiting multiple forms of cell death optimizes ganglion cells survival after retinal ischemia reperfusion injury

Progressive retinal ganglion cells (RGCs) death that triggered by retinal ischemia reperfusion (IR), leads to irreversible visual impairment and blindness, but our knowledge of post-IR neuronal death and related mechanisms is limited. In this study, we first demonstrated that apart from necroptosis, which occurs before apoptosis, ferroptosis, which is characterized by iron deposition and lipid peroxidation, is involved in the whole course of retinal IR in mice. Correspondingly, all three types of RGCs death were found in retina samples from human glaucoma donors. Further, inhibitors of apoptosis, necroptosis, and ferroptosis (z-VAD-FMK, Necrostatin-1, and Ferrostatin-1, respectively) all exhibited marked RGC protection against IR both in mice and primary cultured RGCs, with Ferrostatin-1 conferring the best therapeutic effect, suggesting ferroptosis plays a more prominent role in the process of RGC death. We also found that activated microglia, Muller cells, immune responses, and intracellular reactive oxygen species accumulation following IR were significantly mitigated after each inhibitor treatment, albeit to varying degrees. Moreover, Ferrostatin-1 in combination with z-VAD-FMK and Necrostatin-1 prevented IR-induced RGC death better than any inhibitor alone. These findings stand to advance our knowledge of the post-IR RGC death cascade and guide future therapy for RGC protection.

Automated summary

This study demonstrated the involvement of ferroptosis in retinal ischemia reperfusion (IR) in mice, in addition to necroptosis and apoptosis. The inhibitor Ferrostatin-1 showed the best therapeutic effect in protecting retinal ganglion cells (RGCs) from IR. Inhibition of activated microglia, Muller cells, immune responses, and intracellular reactive oxygen species accumulation was observed after treatment with each inhibitor. Combination therapy with Ferrostatin-1, z-VAD-FMK, and Necrostatin-1 was more effective in preventing IR-induced RGC death than using any inhibitor alone.