Per2 deficiency in microglia alleviates motor dysfunction by inhibiting ferroptosis in spinal cord injury

Microglia play significant roles in spinal cord injury (SCI) progression. Previous studies have suggested that ferroptosis plays a crucial role in exacerbating neuronal death following SCI; however, the role of microglial ferroptosis in SCI and the underlying mechanisms remain elusive. Here, we elucidate that lipid droplets accumulate in microglia to facilitate microglial ferroptosis after SCI. Notably, microglial ferroptosis peaks at 3 days post-injury, after which it decreases. Microglial Period 2 (Per2) expression is elevated after SCI in vivo; this change is highly synchronized with the changes in microglial ferroptosis. Microglia-specific Per2 knockout promoted neurological function recovery by suppressing microglial ferroptosis. In vitro, Per2 overexpression and deficiency amplified and mitigated microglial ferroptosis, respectively. RNA-seq indicated that Gpx4 was downregulated by Per2. Coimmunoprecipitation demonstrated that Per2 directly interacted with PPARα. Overall, our results indicate that Per2 determines the susceptibility of microglial ferroptosis via the PPARα-Gpx4 axis after SCI. Circadian rhythms gene Per2 regulates microglial ferroptosis through the PPARα-GPX4 axis in SCI, which indicates that Per2 may be emerging as a potential therapeutic target for SCI treatment.