Ferritinophagy promotes microglia ferroptosis to aggravate neuroinflammation induced by cerebral ischemia-reperfusion injury via activation of the cGAS-STING signaling pathway

Cerebral ischemia-reperfusion injury (CIRI) is a common and serious complication of reperfusion therapy in patients with ischemic stroke (IS). The regulation of microglia-mediated neuroinflammation to control CIRI has garnered considerable attention. The balance of iron metabolism is key to maintaining the physiological functions of microglia. Nuclear Receptor Coactivator 4 (NCOA4)-mediated ferritinophagy, an important pathway in regulating iron metabolism, is a promising intervention target. However, studies on the impacts of ferritinophagy on microglia-mediated neuroinflammation are lacking. This study aimed to identify potential treatments for CIRI-induced neuroinflammation by focusing on ferritinophagy and the specific mechanisms whereby iron metabolism regulates microglia-mediated neuroinflammation. CIRI induced the activation of ferritinophagy in microglia, characterized by the upregulation of NCOA4, downregulation of Ferritin Heavy Chain 1 (FTH1), and increased intracellular iron levels. This activation contributes to increased ferroptosis, oxidative stress, and the release of inflammatory factors. Silencing NCOA4 or application of the ferroptosis-specific inhibitor Ferrostatin-1 (Fer-1) effectively suppressed the CIRI-induced damage in vivo and in vitro. While Fer-1 addition did not inhibit the CIRI-activated ferritinophagy, it did partially reverse the alleviation of NCOA4 depletion-induced neuroinflammation, suggesting that ferroptosis is an essential intermediate step in ferritinophagy-induced neuroinflammatory damage. Furthermore, using IS-related transcriptomic data, the cGAS-STING pathway was identified as a crucial mechanism connecting ferritinophagy and ferroptosis. Specific inhibition of the cGAS-STING pathway reduced ferritinophagy-induced ferroptosis and neuroinflammation. In summary, our results indicated that ferritinophagy activates the cGAS-STING signaling pathway, which promotes the inflammatory response and oxidative stress in microglia in a ferroptosis-dependent manner, thereby exacerbating CIRI-induced neuroinflammation. These findings provide theoretical support for the clinical treatment of CIRI.