Targeting glial fibrillary acidic protein in glaucoma: a monoclonal antibody approach to modulate glial reactivity and neuroinflammation for neuroprotection.

Background: Glaucoma is a progressive neurodegenerative disorder that leads to irreversible vision loss, with neuroinflammation recognized as a key factor. Overexpression of glial fibrillary acidic protein (GFAP) is linked to glaucoma pathogenesis and plays a pivotal role in astrocyte-driven neuroinflammation. This study aimed to assess the neuroprotective effects of a monoclonal antibody (mAb) targeting GFAP in glaucoma and to elucidate the underlying mechanisms.

Methods: An ocular hypertension (OHT) glaucoma model was established in female Sprague Dawley rats using episcleral vein occlusion. Three doses of GFAP mAb (2.5, 25, 50 µg) or vehicle were administered via intravitreal injection. Retinal nerve fiber layer (RNFL) thickness and photopic electroretinogram were monitored longitudinally. Retinal ganglion cell (RGC) survival and glial responses were evaluated with immunostaining. Western blot and microarray analyses were performed to investigate molecular and pathway alterations. Additionally, a cobalt chloride (CoCl₂)-induced degenerative R28 cell model was used to validate the protective effects of GFAP mAb in vitro. A bioinformatics re-analysis of a public glaucomatous retina protein dataset was conducted using GSEA, GO, and Cytoscape with GENEMANIA.

Results: OHT resulted in a significant loss of RNFL thickness, PhNR amplitude, and RGC survival, all of which were preserved by GFAP mAb treatment. Retinal astrocyte reactivity was inhibited by GFAPmAb in a dose-dependent manner by suppressing GFAP protein overexpression. Notably, 25 µg GFAP mAb effectively regulated both astrocyte and microglial reactivity, leading to a substantial attenuation of neuroinflammation. Mechanistically, GFAP mAb inhibited the p38 MAPK and NF-κB pathways and the NLRP3/Caspase-1/GSDMD axis. In vitro, GFAP mAb improved R28 cell viability under CoCl₂ exposure while reducing cell death via inhibition of pyroptosis. Bioinformatic re-analysis highlighted gliosis as a prominent pathway in the glaucomatous retina and indicated GFAP and Caspase1 as central nodes in the putative mechanism network modulated by GFAP mAb.

Conclusions: This study demonstrates that GFAP mAb inhibits astrogliosis and glial-glial activation, exerting neuroprotection through the inhibition of inflammation and pyroptosis. The findings suggest that targeting GFAP represents a promising immunotherapeutic strategy for glaucoma treatment.