Ferroptosis Contributes to Neuronal Death and Functional Outcome After Traumatic Brain Injury* :

Abstract

Traumatic brain injury (TBI) triggers multiple cell death pathways, possibly including ferroptosis – a recently described cell death pathway that results from accumulation of 15-lipoxygenase (15-LOX)-mediated lipid oxidation products, specifically oxidized phosphatidylethanolamine (PE) containing arachidonic (AA) or adrenic (AdA) acid. This study aimed to investigate whether ferroptosis contributed to the pathogenesis of in vitro and in vivo TBI, and whether inhibition of 15-LOX provided neuroprotection. Cell culture study and randomized, controlled animal study. University research laboratory. HT22 neuronal cell line and adult male C57BL/6 mice. HT22 cells were subjected to pharmacologic induction of ferroptosis or mechanical stretch injury with and without administration of inhibitors of ferroptosis. Mice were subjected to sham or controlled cortical impact (CCI) injury. Injured mice were randomized to receive vehicle or baicalein (12/15-LOX inhibitor) at 10–15 min post-injury. Pharmacological inducers of ferroptosis and mechanical stretch injury resulted in cell death that was rescued by prototypical anti-ferroptotic agents including baicalein. Liquid chromatography tandem-mass spectrometry (LC-MS/MS) revealed the abundance of AA/AdA-PE compared to other AA/AdA-containing phospholipids in the brain. CCI resulted in accumulation of oxidized PE, increased expression of 15-LOX and acyl-CoA synthetase long-chain family member 4 (ACSL4; enzyme which generates substrate for the esterification of AA/AdA into PE), and depletion of glutathione in the ipsilateral cortex. Post-injury administration of baicalein attenuated oxidation of AA/AdA-PE, decreased the number of TUNEL positive cells in the hippocampus, and improved spatial memory acquisition vs vehicle. Biomarkers of ferroptotic death were increased after TBI. Baicalein decreased ferroptotic PE oxidation and improved outcome after CCI, suggesting that 15-LOX pathway might be a valuable therapeutic target after TBI.