Neobaicalein Alleviates Retinal Damage via Microglia-Mediated Astrocyte Phenotypic Transformation.

Abstract

Neobaicalein, a natural flavonoid compound, has shown potential therapeutic effects on various neurodegenerative diseases. However, its role and the underlying mechanisms in retinal damage remain largely unexplored. A mouse model of acute ocular hypertension (AOH) was established by raising intraocular pressure to 90&#xa0;mmHg for 60&#xa0;min. To investigate the involvement of Annexin A3 (ANXA3), adeno-associated virus vectors were used for ANXA3 knockdown and overexpression in vivo. In vitro, cytokine cocktail, Neobaicalein and lipopolysaccharides were applied to stimulate primary mouse astrocytes and BV2 and N9 microglial cell lines, respectively. Retinal injury and cellular changes were evaluated by histological analysis, immunofluorescence, ELISA, qPCR, and Western blotting. Neobaicalein treatment (25&#xa0;mg/kg) significantly preserved retinal integrity in AOH mice by increasing the thickness of the inner plexiform layer (p&#x2009;<&#x2009;0.01) and inner nuclear layer (p&#x2009;<&#x2009;0.01), and enhanced RGC survival (BRN3A&#x207a; and RBPMS&#x207a; cells, both p&#x2009;<&#x2009;0.05). It markedly reduced retinal astrocyte activation (GFAP intensity, p&#x2009;<&#x2009;0.001), decreased expression of A1 astrocytic markers (C3, GBP2), and increased A2 markers (S100A10, PTX3). Microglial activation and pro-A1 cytokine secretion were also suppressed. Neobaicalein decreased ANXA3 expression in activated microglia. Importantly, ANXA3 knockdown reproduced key protective effects of Neobaicalein, while its overexpression diminished the efficacy of Neobaicalein in alleviating AOH-induced retinal damage. These findings demonstrated that Neobaicalein confers retinal protection against AOH-induced injury by modulating the microglia-astrocyte axis via ANXA3 inhibition, highlighting a novel mechanism and therapeutic strategy for glaucomatous neurodegeneration.