Single Gene Injection Shields Retinal Cells From Glaucoma Damage

Glaucoma is the leading cause of irreversible blindness worldwide, affecting over 80 million people. Its hallmark is progressive retinal ganglion cell (RGC) death driven not only by elevated intraocular pressure but also by neuroinflammation, cholesterol dysregulation, and mitochondrial dysfunction — none of which are addressed by current pressure-lowering treatments. This study, led by Won-Kyu Ju and colleagues at UC San Diego and published in Molecular Therapy, investigates apolipoprotein A-I binding protein (AIBP) as a novel therapeutic target and demonstrates that AAV-mediated AIBP restoration provides robust neuroprotection in multiple glaucoma models.

The researchers first established translational relevance by showing that AIBP and its downstream cholesterol transporter ABCA1 were significantly downregulated in retinal tissue from human glaucoma patients compared to healthy controls. Simultaneously, Toll-like receptor 4 (TLR4), interleukin-1β (IL-1β), and retinal cholesterol content were all elevated. These findings were replicated in two established mouse glaucoma models — microbead-induced ocular hypertension and the DBA/2J spontaneous glaucoma model — confirming that AIBP deficiency is a conserved feature of glaucomatous neurodegeneration across species.

To test therapeutic restoration, the team delivered AAV2 carrying the AIBP gene via a single intravitreal injection in glaucomatous mice. AAV-AIBP treatment significantly preserved RGC density and retinal nerve fiber layer thickness compared to AAV-control injected animals. Electroretinography and pattern ERG demonstrated meaningful functional recovery, with treated animals showing improved visual response amplitudes. Critically, AAV-AIBP reduced TLR4 protein expression, diminished IL-1β levels, and decreased TLR4 localization to cholesterol-rich lipid rafts — the membrane microdomains that amplify inflammatory signaling. Free cholesterol accumulation in the retina was also significantly attenuated.

A key mechanistic finding involved Müller glia, the primary support cells of the retina. AAV-AIBP promoted greater mitochondrial complexity and improved mitochondrial function in these cells in vivo, assessed through high-resolution electron microscopy and functional assays. In parallel cell culture experiments, recombinant AIBP protein suppressed TLR4 and IL-1β activation and rescued mitochondrial dysfunction in Müller glia subjected to elevated hydrostatic pressure — a standard in vitro glaucoma stress model. These complementary in vivo and in vitro data confirm that AIBP acts through a dual mechanism: resolving cholesterol-driven lipid raft inflammatory signaling and preserving mitochondrial integrity.

To establish the necessity of AIBP, the team performed an RGC-specific AIBP knockdown using AAV-delivered shRNA. Mice with AIBP silenced specifically in RGCs exhibited significantly accelerated RGC loss and worsened visual dysfunction under glaucomatous conditions, confirming that endogenous AIBP is actively neuroprotective rather than merely a correlative marker. Together, these gain- and loss-of-function experiments build a compelling case for AIBP as both a driver of retinal resilience and a druggable target. The study positions a single-injection AAV-AIBP therapy as a clinically translatable neuroprotective strategy for human glaucoma, complementary to existing IOP-lowering interventions.