371 Fractalkine isoforms using gene therapy differentially regulate microglia activation and vascular damage in the diabetic retina

Abstract

OBJECTIVES/GOALS: Retinal inflammation caused by the activation of resident macrophages (microglia) during diabetes exacerbates glial cell dysfunction, resulting in neuronal loss. The goal is to use rAAV gene therapy to deliver neuronal-derived fractalkine (FKN), minimizing inflammation and vascular damage in the diabetic retina. METHODS/STUDY POPULATION: The human microglial receptor (CX3CR1) binds to FKN, a protein that is expressed on neuronal membranes (mFKN), and undergoes constitutive cleavage to release a soluble domain (sFKN). Deficiencies in CX3CR1 or FKN showed increased microglial activation and elevated retinal pathology. To understand the mechanism by which mFKN and sFKN regulate microglia function, recombinant adeno-associated viruses (rAAVs) expressing mFKN or sFKN were delivered to intact retinas during diabetes. Markers of neuronal loss, vascular damage, and inflammation were analyzed. We hypothesize that the administration of rAAV-sFKN but not rAAV-mFKN will prevent vascular and neuronal damage, and improve visual function. RESULTS/ANTICIPATED RESULTS: rAAV-sFKN minimized microglial activation, blood vessel rupture, fibrinogen deposition, and prevented neuronal loss, compared to mice treated with rAAV-mFKN in a mouse model of diabetic retinopathy (DR). rAAV-sFKN treated mice showed improved visual acuity using a two-choice discrimination task through learning-based behavior. rAAV-sFKN treatment correlated with the success rate of the mice finding the reward based on their ability to distinguish visual cues. Future studies will test the effects of rAAV-sFKN and rAAV-mFKN on microglia inflammatory cytokine release, optic nerve damage and synaptic neurotransmission, peripheral immune responses, and transcriptomic changes in microglia during diabetes. DISCUSSION/SIGNIFICANCE: Current therapies for DR are ineffective in restoring vision. rAAVs-sFKN delivery appears to act as a neuroprotective approach in the diabetic retina. sFKN serves as an alternative pathway to implement translational and therapeutic approaches, minimizing pathology and improving visual function.