Role and targeting of High Mobility Group Box 1 (HMGB1) in choroidal neovascularization for neovascular age-related macular degeneration

Abstract

Purpose : Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly in the US. Severe vision loss in AMD is largely caused by choroidal neovascularization (CNV), the hallmark of the wet (neovascular) form of AMD. While intravitreal anti-VEGF injection has greatly improved the care of patients with wet AMD, there is a great need for new therapeutic approaches for wet AMD beyond anti-VEGF drugs. HMGB1 is a nuclear and cytoplasmic protein that is secreted by activated immune cells and released by dying cells. In the extracellular environment, HMGB1 acts as a damage-associated molecular pattern molecule and is an important mediator of inflammation and angiogenesis. The objective of this study was to investigate the role of HMGB1 and its utility for the treatment of wet AMD using the mouse model of laser-induced CNV.

Methods : In C57BL/6J wild-type mice, 1 ug of HMGB1-neutralizing Ab was intravitreally injected in both eyes immediately after laser-induced burns. For control, the same amount of IgG₂ was injected in a separate group of mice. For genetic loss of function studies, HMGB1 conditional KO (cKO) mice were used. Cdh5-Cre;Hmgb1^lox/lox (EC-specific), Six3Cre;Hmgb1^lox/lox (Macroglia-specific) mice and their littermate controls (Hmgb1^lox/lox) between the ages of 6 to 9 weeks were subjected to laser-induced CNV. Fundus fluorescein angiography (FFA) was performed at 7 days (D7) after laser to assess CNV leakage. CNV lesion size was assessed at day 7 by choroidal flatmounting and lectin staining, respectively.

Results : In C57BL/6J mice, a single HMGB1-neutralizing antibody injection significantly (p<0.05) reduced fluorescein leakage and CNV lesion size at D7 compared with IgG₂-injected controls. In cKO mice, EC-specific Hmgb1 KO mice exhibited significant reduction (p<0.05) in both fluorescein leakage and CNV lesion size compared with littermate controls. There were no differences in fluorescein leakage or CNV lesion size between macroglia-specific Hmgb1 KO and littermate controls.

Conclusions : These results suggest that HMGB1, especially endothelial cell HMGB1, plays an important role in promoting CNV, and that targeting HMGB1 could represent an additional therapeutic strategy for neovascular AMD.

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