Abstract
Purpose :
Age-related macular degeneration (AMD) a leading cause of vision loss, and despite extensive research efforts, remains poorly understood. Choroidal vessel outgrowth, the defining feature of neovascular AMD (nAMD), is responsible for about 90% of the vision loss from AMD despite occurring in only about 10% of all AMD cases. We identified GPR143, a GPCR activated by L-DOPA, as a likely component of the profound racial bias of AMD. We determined that nAMD patients given L-DOPA had reduced need for anti-VEGF injection therapy along with improved visual outcomes. The reduction in anti-VEGF was significant, a 52% reduction in necessary anti-VEGF injections to treat nAMD. However, almost ½ of the patients did not respond to L-DOPA and we do not know why. We hypothesize that GPR143 activation reduces angiogenesis by stopping exosome release in response to hypoxia.
Methods :
GRR143 activation by L-DOPA in RPE upregulates PEDF and down regulates both VEGF and extracellular vehicles (EVs) release. We investigated the effect of EVs released under hypoxic (3%) and normoxic (20%) conditions from the porcine RPE (pRPE) cells and human aorta endothelial cells (hAEC) in coculture assays to model choroidal neovascularization in AMD. EVs collected from cells were tested for angiogenic activity using a series of assays, including hAEC proliferation, tube formation, VEGF and PEDF measurements.
Results :
Our results showed that RPE EVs stimulated angiogenesis in hAEC. This stimulation was evident through multiple assays, including increased EVs from HAEC cells in a hypoxic environment compared to normal conditions (P<0.01). We also found significant increase in HAEC number and length of tubules in the hypoxic environment. The effect of EVs was dose-dependent, and we found that L-Dopa decreased the number of pRPE EVs released, resulting in a reduced angiogenic potential in the hAEC.
Conclusions :
We identified the GPR143 activities that may underly the positive effect of L-DOPA on AMD in patients. L-DOPA reduces the EVs released significantly in both pRPE and hAEC, along with reduction of endothelial tube formation in the cocultures. This illustrates on the novel effects of GPR143 signaling and its control of EVs likely related to its positive effects on retinal angiogenesis as part of nAMD therapy with L-DOPA.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.