GPR30-driven fatty acid oxidation targeted by ginsenoside Rd maintains mitochondrial redox homeostasis to restore vascular barrier in diabetic retinopathy

Abstract

Blood-retinal barrier (BRB) breakdown, a pivotal contributor to multiple retinal vascular diseases, manifests as a progressive increase in vascular permeability induced by various pathological stimuli. The functional plasticity of retinal endothelial cells can be intricately shaped by metabolic alteration. However, little is known about the mechanisms through which endothelial metabolic disorders trigger the dissolution of inter-vascular junctions and the selective approaches to targeting metabolic homeostasis. Herein, we identify AMPK-associated fatty acid oxidation (FAO) inhibition as a critical driver of vascular barrier dysfunction via exacerbating redox imbalance. Pharmacological facilitation of FAO by ginsenoside Rd (Rd) suppresses BRB collapse and other secondary retinal damage in diabetic retinopathy (DR). Mechanistically, Rd targets GPR30 to phosphorylate AMPK via the PKA-LKB1-AMPK kinase cascade. The AMPK activation induced by Rd revitalizes hyperglycemia-compromised FAO, and then sustains mitochondrial NADPH regeneration by emphasis on IDH2 at various levels, including substrate supply, transcription, and post-translational modifications. Therefore, Rd alleviates the disruption of BRB integrity driven by mitochondrial oxidative stress, with the vasculoprotection of Rd diminished by GPR30 knockdown and pharmacological attenuation of AMPK. These findings collectively reveal the previously-unanticipated role of endothelial FAO in heightened retinal vascular leakage, and highlight the potential translational application of GPR30 agonism with Rd to mitigate barrier dysfunction, providing a metabolic regulatory therapeutic strategy for DR.