Inhibition of neuronal ferroptosis in the acute phase of intracerebral hemorrhage shows long-term cerebroprotective effects

Abstract

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke because it has few viable therapeutic options to intervene against primary or second brain injury. Recently, evidence has suggested that ferroptosis, a nonapoptotic form of cell death, is involved in ICH. In this study, we examined whether ICH-induced neuron death is partly ferroptotic in humans and assessed its temporal and spatial characteristics in mice. Furthermore, the ferroptosis inhibitor ferrostatin-1 (Fer-1) was used to examine the role of ferroptosis after ICH. Fold changes in ferroptosis-related gene expression, intracellular iron levels, malondialdehyde (MDA) levels, and both protein levels and cellular localization of cyclooxygenase-2 (COX-2) were measured to monitor ferroptosis. Transmission electron microscopy (TEM) was also performed to examine the ultrastructure of cells after ICH. We found that the expression level of prostaglandin-endoperoxide synthase (PTGS2) was increased in both in vitro and in vivo ICH models; by comparison, expression level of RPL8 was increased in human brain tissue. In mice, iron and MDA levels were significantly increased 3 h after ICH; COX-2 levels were increased at 12 h after ICH and peaked at 3 days after ICH; COX-2 colocalized with NeuN (a neuronal biomarker); and TEM showed that shrunken mitochondria were found at 3 h, 3 days, and 7 days after ICH. Moreover, ICH-induced neurological deficits, memory impairment and brain atrophy were reduced by Fer-1 treatment. Our results demonstrated that neuronal ferroptosis occurs during the acute phase of ICH in brain areas distant from the hematoma and that inhibition of ferroptosis by Fer-1 exerted a long-term cerebroprotective effect.

Keywords: Ferroptosis; Ferrostatin-1; Intracerebral hemorrhage; Neuroprotection; Secondary brain injury.