Abstract
Purpose :
Pathological retinal neovascularization (PNV) occurs in proliferative diabetic retinopathy (PDR) and retinopathy of prematurity (ROP) the leading causes of blindness in working age adults and children respectively. Retinal tissue hypoxia is a key driver of PNV that results in uncontrolled vessel sprouting and the formation of immature and leaky blood vessels. Current treatments for PNV involve the use of agents that neutralize or inhibit vascular endothelial growth factor (VEGF). However, these treatments have adverse effects, so exploring new therapeutic targets is crucial. Here we investigated the role of the enzyme histone deacetylase 3 (HDAC3) in pathological retinal angiogenesis.
Methods :
In vivo studies were conducted using C57BL/6J mice pups subjected to oxygen-induced retinopathy (OIR). Retinal tissues were further processed for Western Blotting and immunolabeling. In vitro experiments were conducted using bovine retinal endothelial cells (BRE) subjected to normoxia or oxygen glucose deprivation (OGD) followed by reoxygenation (R). Cells were treated with the HDAC3 inhibitor, RGFP966 (2, 8 μM), or DMSO for control. Endpoints included assays of migration, and tube formation as important steps in new vessel formation. Mitochondria morphology was visualized using MitoTracker dye.
Results :
HDAC3 is upregulated in the OIR retina vessels as measured by Western blotting and immunolabeling. In human DR sections, HDAC3 localized in retina surface vessels. In vitro, HDAC3 was upregulated in BRE after OGD/R and showed a complete nuclear translocation. Treatment of BRE with the HDAC3 inhibitor RGFP966 reduced angiogenesis (cell migration and tube formation) under hypoxic conditions, and also reduced the OGD/R-induced mitochondrial fission without affecting cell viability. Furthermore, RGFP966 treatment suppressed the rate-limiting glycolysis enzyme, hexokinase 2 (HK2). Similar to HDAC3 inhibition, treatment with the HK2 inhibitor, lonidamine (50, 100 µM), suppressed BRE angiogenesis and mitofission.
Conclusions :
Endothelial HDAC3 mediates pathological retinal angiogenesis under hypoxic conditions possibly via HK2 mediated metabolic reprograming to a glycolytic phenotype and suppression of mitochondrial function. Future experiments will further elucidate the underlying mechanisms.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.