HABP2 Encapsulated by Peripheral Blood-Derived Exosomes Suppresses Astrocyte Autophagy to Exacerbate Neuroinflammatory Injury in Mice with Ischemic Stroke

Exosomes are shown to be involved in the regulation of neuroinflammatory injury. The current study analyzed how peripheral blood-derived exosomes affected hyaluronan-binding protein 2 (HABP2) expression to regulate neuroinflammatory injury after ischemic stroke (IS). An IS animal model was stimulated by middle cerebral artery occlusion (MCAO), followed by injection of lentivirus. Peripheral blood samples were collected from MCAO mice after different treatments. The cerebral infarction volume, astrocyte activation, and neuroinflammation were observed by TTC staining, immunofluorescence, and ELISA, respectively. HABP2 was highly expressed in the brain tissues of MCAO mice. Also, an enhancement of HABP2 was noted in their peripheral blood-derived exosomes, while loss of HABP2 in peripheral blood-derived exosomes promoted the astrocyte autophagy and reduced the release of the inflammatory factors as well as the apoptosis of neuronal cells. PAR1 overexpression reversed the effect of HABP2 loss on autophagy and neuroinflammation in MCAO mice. Additionally, the agonist of the PI3K/AKT/mTOR pathway, SC79, could also reverse the effect of sh-PAR1 on neuroinflammation. Mechanistically, HABP2 enhanced PAR1 to activate the PI3K/AKT/mTOR pathway, thereby suppressing cell autophagy. Overall, HABP2 in peripheral blood-derived exosomes can activate the PAR1/PI3K/AKT/mTOR pathway to reduce autophagy and aggravate neuroinflammatory injury after IS.