Long-Acting RXR Agonism Preserves Retinal Function and Modulates Inflammation in Diabetic Retinopathy

Area of Science:

• Ophthalmology
• Endocrinology
• Pharmacology

Background:

• Diabetic retinopathy (DR) is a major cause of vision loss linked to reduced nuclear retinoid X receptor (RXR) activity.
• High glucose levels in retinal explants downregulate RXR, PPAR, and LXR-β, impacting lipid metabolism.
• RXR agonists, like UAB126, can restore nuclear receptor signaling and form RXR/PPAR heterodimers.

Purpose of the Study:

• To evaluate the long-term pharmacokinetic, molecular, and functional effects of UAB126 microparticles (UAB126-MP) in diabetic mouse retinas.
• To assess the therapeutic potential of sustained-release RXR agonism for diabetic retinopathy.

Main Methods:

• A single intravitreal injection of UAB126-MP was administered to db/db mice.
• Pharmacokinetic analysis tracked drug exposure up to 6 months.
• Retinal RXRα expression, electroretinographic responses, photoreceptor function, and inflammatory cell infiltration were analyzed.

Main Results:

• UAB126-MP provided sustained drug exposure for up to 6 months and increased retinal RXRα expression.
• Scotopic and photopic electroretinographic responses were preserved at 2 months, and cone photoreceptor function at 6 months.
• While UAB126-MP reduced retinal macrophage/microglial infiltration and myeloid cell presence, it did not prevent acellular capillaries.

Conclusions:

• RXR agonism, delivered via UAB126-MP, offers durable retinal protection with neuroprotective and anti-inflammatory actions.
• The therapy supports neuronal function and modulates the immune response in the retina.
• UAB126-MP demonstrates potential as a long-acting therapeutic strategy for diabetic retinopathy, primarily through nuclear receptor-mediated pathways.