Abstract
Purpose :
Ischemia-induced retinopathy is a pathological feature of common visual disorders including diabetic retinopathy (DR). To date, there is no clinically effective treatment that can protect the retinal. Previous reports showed that the enzyme histone deacetylase 3 (HDAC3) is upregulated in retinal neurons and contribute to their apoptosis after traumatic optic neuropathy. In this study, we investigated the pathological role of myeloid HDAC3 in retinal ischemia-reperfusion (IR) injury and macrophage inflammatory response.
Methods :
We subjected myeloid-specific HDAC3 KO mice (M-HDAC3 KO under LysM cre) and floxed controls to IR injury by raising the intraocular pressure for 60 minutes followed by reperfusion. Subsequently, we examined the neurovascular degeneration (n=5-6), vascular leakage (n=6-8), and retinal thickness (n=3-6) after injury using immunolabeling, trypsin digestion, western blotting, and optical coherence tomography respectively. In vitro, macrophages isolated from M-HDAC3 KO or floxed control mice were stimulated with lipopolysaccharide (LPS) to measure their inflammatory response by cytokine production and metabolic reprogramming using Seahorse.
Results :
HDAC3 co-localized with Iba1+ microglia/macrophages in the injured retina at 48 h after IR. M-HDAC3 deletion was neurovascular protective as measured by neuron labeling with NeuN (82.9±4.7% neuronal survival vs 61±8% in injured control, mean±SEM, p<0.05) and number of acellular capillary/mm2 (18.4±3.3 vs 26.7±2.4 in injured control, p<0.05) at days 7 and 14 post-IR. Decreased vascular leakage was observed in injured M-HDAC3 KO retinas compared to their injured controls as measured by albumin extravasation (p<0.05) at day 2. Furthermore, HDAC3 deletion significantly preserved the retinal thickness (98.33±1.5% of sham vs 86.6±2.4% in injured control, p<0.05) at day 14. In vitro, LPS stimulated HDAC3 KO macrophages exhibited a reduced inflammatory response evident by decreased expression of the cytokine, TNF-α (p<0.01), and reduced metabolic programming to the proinflammatory glycolytic phenotype (p<0.05).
Conclusions :
Myeloid-specific HDAC3 deletion is neurovascular protective against retinal IR-injury and dampens the macrophage inflammatory response. Suppression of myeloid HDAC3 may provide a novel therapeutic strategy to mitigate inflammation and associated neurovascular injury in Ischemia-induced retinopathy.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.