Intranasal Administrations of AP39-Loaded Liposomes Selectively Deliver H2Sto Neuronal Mitochondria to Protect Neonatal Hypoxia–Ischemiaby Targeting ERK1/2 and Caspase‑1

Mitochondrial dysfunction contributes to the pathology of hypoxia–ischemia (HI) brain damage by aberrant production of ROS. Hydrogen sulfide (H₂S) has been demonstrated to exert neuroprotective effects through antioxidant mechanisms. However, the diffusion of H₂S <i>in vivo</i> is not specifically targeted and may even be systemically toxic. In this study, based on mitochondria-targeted H₂S donor AP39, we fabricated liposomes encapsulating AP39 (AP39@Lip) via intranasal delivery to improve functional recovery after HI brain injury. This study presents that intranasal administration of AP39@Lip was capable of attenuating acute brain injury by inhibiting mitochondrial dysfunction, apoptosis, neuroinflammation, and ROS production in the lesional cortex 3 days after HI brain injury. Similarly, AP39@Lip was observed to restore both short- and long-term function following HI injury without obvious toxicity. Mechanistically, the therapeutic effects of AP39@Lip mainly relied on its colocalization with neuronal mitochondria 24 h after administration and reversed H₂S levels in the lesional cortex. Moreover, molecular docking and cellular thermal shift assay suggest that AP39 inhibited the activation of ERK1/2 and caspase-1 by directly binding to ERK1/2 or caspase-1. These results indicate that intranasal administration of AP39@Lip selectively delivered H₂S to neuronal mitochondria and mitigated mitochondrial damage following HI insult by targeting ERK1/2 and caspase-1.