Astrocyte-derived exosomes suppress autophagy and ameliorate neuronal damage in experimental ischemic stroke

Abstract

The aim of this study was to investigate the role of astrocyte-derived exosomes (AS-Exo) on neuronal damage in ischemic stroke. We isolated astrocytes from 3- to 4-day-old C57BL/6 mice and astrocytes were identified by GFAP immunostaining. Exosomes were obtained from astrocyte supernatant by overspeed centrifugation. For investigating the effect of AS-Exo on the apoptosis of neurons after oxygen and glucose deprivation (OGD), the exosome labeling and uptake by neurons were observed by confocal laser microscopy, then HT-22 cell vitality and apoptosis were determined by Cell Counting Kit-8 (CCK-8) assay and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, respectively. Tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) in OGD-induced HT-22 was analyzed by Enzyme-linked immunosorbent assay (ELISA). Apoptosis-related protein in HT-22 was analyzed by Western blot. For investigating the effect of AS-Exo on the OGD neurons autophagy, expression of Beclin-1, LC3-I, LC3-II and P62 in OGD-induced HT-22 was analyzed by Western blot. For animal experiments, C57BL/6 mice (6–8 weeks old) models of middle cerebral artery occlusion were used to create permanent focal ischemia. AS-Exo were injected intravenously through the tail vein into ischemic mice at a concentration of 80 μg per 2 ml after 60 min of the ligation operation The results showed that AS-Exo enhanced neurons viability; inhibited OGD-induced apoptosis, inhibited OGD-induced expressions of caspase-3 and Bax and levels of TNF-α, IL-6 and IL-1β in HT-22 cells. Further findings showed AS-Exo inhibited OGD-induced neurons apoptosis via regulating autophagy. AS-Exo ameliorated neuronal damage through regulating autophagy in vivo. Our data indicate that AS-Exo suppress autophagy and ameliorate neuronal damage in experimental ischemic stroke.