Intermittent Hypoxia Preconditioning Protects Against Ischemic Brain Injury in Mice via a PF4-Dependent Paracrine...

Area of Science:

• Neuroscience
• Cardiovascular System
• Cell Biology

Background:

• Intermittent hypoxia (IH) preconditioning enhances brain resilience against ischemic injury.
• The precise mechanisms underlying IH-induced neuroprotection are not fully understood.
• Peripheral paracrine mechanisms are hypothesized to mediate IH-induced neuroprotection.

Purpose of the Study:

• To investigate the role of peripheral paracrine mechanisms in IH-induced neuroprotection.
• To identify circulating mediators responsible for IH-induced neuroprotection.
• To evaluate the therapeutic potential of IH-derived plasma (IHP) and identified mediators for ischemic stroke.

Main Methods:

• Administered IH-derived plasma (IHP) or normoxic plasma to mice before and after stroke models (distal middle cerebral artery occlusion and transient MCAO).
• Assessed infarct volume and neurological deficits as primary outcomes.
• Utilized proteomics to identify candidate mediators, followed by antibody-mediated depletion and recombinant protein supplementation for validation. Examined blood-brain barrier integrity.

Main Results:

• Systemic IHP administration reduced infarct volume and improved sensorimotor function after stroke.
• Poststroke IHP administration provided acute and sustained neuroprotection in transient MCAO models.
• Proteomic analysis identified platelet factor 4 (PF4) as a key IH-upregulated protein; PF4 depletion abolished neuroprotection, while recombinant PF4 conferred protection and preserved blood-brain barrier integrity.

Conclusions:

• Platelet factor 4 (PF4) is identified as a crucial paracrine mediator of IH-induced neuroprotection.
• IHP and PF4-based interventions show therapeutic promise for ischemic stroke.
• Findings support the development of novel treatments targeting PF4 for stroke recovery.