BETA-HYDROXYBUTYRATE STIMULATES THE AUTOPHAGY-LYSOSOMAL AXIS IN ASTROCYTES

Astrocytes perform multiple functions, including preservation of neuronal survival under stress conditions, process that critically depend on a functional autophagy–lysosomal axis. Beta-hydroxybutyrate (D-BHB) is a ketone body with reported neuroprotective properties, partly attributed to its ability to modulate autophagy in neurons; however, its effects on astrocyte autophagy and cytoprotection remain poorly understood. Here, we investigated whether D-BHB modulates astrocyte autophagy and lysosomal biogenesis under basal conditions and whether these effects contribute to astrocyte viability under oxygen-glucose deprivation (OGD). Primary astrocytes were exposed to D-BHB, and autophagy-related signaling and flux were assessed by immunoblot, immunofluorescence, and fluorescent reporters. D-BHB increased LC3-II and reduced SQSTM1/p62 levels, and elevated autophagosome number, suggesting enhanced autophagic flux. D-BHB induces phosphorylation of AMPK and ULK1, and the inactivation of mTORC1, promoting autophagy initiation. Pharmacological inhibition of sirtuin activity or the AMPK/ULK1 pathway abated D-BHB-induced autophagy, suggesting this pathway dependence. Additionally, D-BHB promoted TFEB activation, increased LAMP1 abundance and lysosomal number, suggesting enhanced lysosomal biogenesis. Also, D-BHB improved astrocyte survival following OGD, an effect dependent on autophagy initiation and autophagy flux, as protection was abolished by chloroquine and pharmacologic inhibitors of sirtuins and AMPK/ULK1 activity. These findings demonstrate that D-BHB confers astrocyte resistance to metabolic stress through coordinated regulation of the autophagy–lysosomal axis, positioning astrocytes as possible active contributors to the neuroprotective effects of ketone bodies in acute brain injury.
This work was supported by PAPIIT-UNAM IN215825, and SECIHTI 2021-00018-02NACF-19488 and CBF-2025-I-1041.