SS-31 Peptide Protects Brain After Cardiac Arrest by Inhibiting Microglial Damage

Following a cardiac arrest, the brain suffers severe ischemic-reperfusion injury, leading to significant neurological deficits and long-term disability. A critical component of this damage is neuroinflammation, primarily driven by activated microglia (immune cells of the brain). Current therapeutic strategies are limited in their ability to effectively mitigate this complex injury. This study addresses how the peptide SS-31 can modulate harmful microglial responses, specifically ferroptosis and polarization, to improve post-cardiac arrest brain outcomes.

Treatment with SS-31 significantly ameliorated brain injury and improved neurological function in the rat model. The high-dose 3 mg/kg SS-31 group demonstrated a remarkable 45% reduction in neuronal cell death and a 30% improvement in neurological severity scores compared to the saline control group (p<0.001). Specifically, SS-31 effectively inhibited microglial ferroptosis (a form of iron-dependent cell death), evidenced by a 38% decrease in lipid peroxidation and a 25% reduction in iron accumulation within microglial cells. Furthermore, the peptide modulated microglial polarization, shifting them from a detrimental pro-inflammatory M1 phenotype to a protective anti-inflammatory M2 phenotype, with a 2.1-fold decrease in M1 markers and a 1.8-fold increase in M2 markers. These beneficial effects were observed in a dose-dependent manner, with the 3 mg/kg dose yielding the most significant improvements.