Butyrate Inhibits Retinal Neovascularization by regulating HDAC1-Mediated Sp1-HIF1α/VEGF Signaling

Abstract

Purpose : Retinopathy of prematurity (ROP) is a leading cause of childhood blindness. Abnormal retinal neovascularization is a primary characteristic of the disease. Available therapies do not completely ameliorate pathology progression and risk of vision loss. The current study focuses on butyrate and signaling mechanisms mediated thereby as a potential new strategy to prevent and treat ROP. Our preliminary data in premature human infants with ROP reveal a striking reduction in fecal levels of butyrate, a gut microbiome-derived metabolite. This aligns with our observation that oral butyrate supplementation improves retinal neovascularization in a mouse model of ROP. These studies highlight a potential protective role for butyrate in the neonatal retina and its potential as a novel therapeutic strategy. Herein, we investigate the underlying mechanisms for butyrate-mediated regulation of retinal neovascularization.

Methods : We subjected wild-type C57BL/6J mice to the standard OIR (oxygen-induced retinopathy) procedure as per Smith et al. HDAC (Histone deacetylase) expression and activity were then evaluated in retinas collected on postnatal days 12, 14, and 17. Complementary in vitro assays were performed using human retinal endothelial cells (HRECs) to assess the effects of butyrate (1, 2, or 5 mM) on hypoxia (2% oxygen) -induced tube formation, HIF1α (Hypoxia-inducible factor 1-alpha) and VEGF (Vascular endothelial growth factor) protein expression, HDAC activity, and Sp1 acetylation. STRING analysis and immunoprecipitation assays were additionally performed to investigate HDAC1-Sp1 interaction.

Results : OIR mice exhibited elevated HDAC activity in general and a specific increase in HDAC1 expression. Butyrate potently inhibited hypoxia-induced tube formation in HRECs. Mechanistic studies highlight butyrate-induced suppressed HIF1α and VEGF expression via increased H3 acetylation and decreased HDAC activity as mechanisms of key importance to these effects. STRING analysis and immunoprecipitation assays additionally revealed HDAC1 as a potential Sp1 interactor. Butyrate treatment induced Sp1 acetylation, suggesting a regulatory link between HDAC1 and Sp1 in VEGF expression.

Conclusions : Our findings demonstrate that butyrate inhibits retinal angiogenesis by suppressing HDAC1-mediated Sp1-HIF1α/VEGF signaling, suggesting its potential as a therapeutic strategy for ROP.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.