ANGPTL4 Induces Aberrant Lymphatic-Like Remodeling in Proliferative Diabetic Retinopathy

Diabetic retinopathy (DR) is a leading cause of vision loss in working-age adults and often progresses to proliferative diabetic retinopathy (PDR) with irreversible complications. Anti-vascular endothelial growth factor (VEGF) therapy remains the first-line treatment; however, resistance poses a significant challenge, necessitating alternative therapeutic targets. This study explores the role of angiopoietin-like protein 4 (ANGPTL4) in PDR pathogenesis, emphasizing vascular-immune-lymphatic interactions. We found significantly elevated ANGPTL4 and VEGF-C levels in the vitreous humor of patients with PDR, which were not affected by anti-VEGF therapy. In vivo, full-length ANGPTL4 and its C-terminal fragment promoted pathological angiogenesis and lymphatic-like remodeling in diabetic murine retinas, characterized by increased lymphatic vessel endothelial hyaluronan receptor 1, prospero homeobox 1, and VEGF receptor 3 (VEGFR3) expression. Single-cell sequencing further revealed ANGPTL4-driven immune dysregulation, with abnormal infiltration of CD4+ T cells and dendritic cells. Knockdown of ANGPTL4 in mice with oxygen-induced retinopathy alleviated retinal hypoxia, neovascularization, and vascular leakage. Mechanistically, retinal hypoxia markedly increased ANGPTL4 expression levels in the retina, which activated the activator protein-1 (AP-1) transcription factor complex and promoted Cd83 transcription in mouse heart microvascular endothelial cells. Additionally, ANGPTL4 bound to neuropilin-1 (NRP1)/VEGFR3, driving human lymphatic endothelial cell proliferation and lymphatic vessel ingrowth from the optic nerve sheath into the retina, a finding that suggests a novel pathway independent of angiopoietin-Tie signaling. These findings establish ANGPTL4 as a key mediator of immune-vascular interactions in PDR and a potential therapeutic target to address both pathological angiogenesis and lymphatic dysfunction. ARTICLE HIGHLIGHTS: Some patients with proliferative diabetic retinopathy (PDR) have poor responses to anti-vascular endothelial growth factor (anti-VEGF) therapy. This situation highlights the need for additional therapeutic approaches. In proliferative diabetic retinopathy, what is the role of ANGPTL4 that differs from VEGF? We found that ANGPTL4 is elevated in the vitreous humor of patients with PDR who are poorly responsive to anti-VEGF therapy. ANGPTL4, particularly its C-terminal fragment, causes retinal lymphatic-like remodeling in diabetic mice. This study provides novel insights into the complex interplay between immune activation, neovascularization, and lymphatic-like remodeling in PDR. Our findings deepen our understanding of PDR pathophysiology and propose a promising therapeutic target.