ABSTRACT
Neovascularization is a key feature of ischemic retinal diseases and the wet form of age-related macular degeneration (AMD), all leading causes of severe vision loss. Vascular endothelial growth factor (VEGF) inhibitors have transformed the treatment of these disorders. Millions of patients have been treated with these drugs worldwide. However, in real-life clinical settings, many patients do not experience the same degree of benefit observed in clinical trials, in part because they receive fewer anti-VEGF injections. Therefore, there is an urgent need to discover and identify novel long-acting VEGF inhibitors. We hypothesized that binding to heparan-sulfate proteoglycans (HSPG) in the vitreous, and possibly other ocular structures, may be a strategy to promote intraocular retention, ultimately leading to a reduced burden of intravitreal injections. We designed a series of VEGF receptor 1 variants and identified some with strong heparin-binding characteristics and ability to bind to vitreous matrix. Our data indicate that some of our variants have longer duration and greater efficacy in animal models of intraocular neovascularization than current standard of care. Our study represents a systematic attempt to exploit the functional diversity associated with heparin affinity of a VEGF receptor.
Subject(s)
Choroidal Neovascularization/drug therapy , Heparan Sulfate Proteoglycans/pharmacology , Macular Degeneration/drug therapy , Vascular Endothelial Growth Factor Receptor-1/antagonists & inhibitors , Vascular Endothelial Growth Factor Receptor-2/genetics , Angiogenesis Inhibitors/chemistry , Animals , Cell Proliferation/drug effects , Choroidal Neovascularization/genetics , Choroidal Neovascularization/pathology , Crystallography, X-Ray , Endothelial Cells/drug effects , Eye/drug effects , Eye/pathology , Heparan Sulfate Proteoglycans/genetics , Heparan Sulfate Proteoglycans/immunology , Heparin/genetics , Human Umbilical Vein Endothelial Cells , Humans , Immunoglobulin Fc Fragments/genetics , Immunoglobulin Fc Fragments/pharmacology , Immunoglobulin Fc Fragments/ultrastructure , Intravitreal Injections , Macular Degeneration/genetics , Macular Degeneration/pathology , Mice , Protein Isoforms/antagonists & inhibitors , Protein Isoforms/genetics , Vascular Endothelial Growth Factor Receptor-1/genetics , Vascular Endothelial Growth Factor Receptor-1/ultrastructure , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Vitreous Body/drug effectsABSTRACT
The blood vessels in the central nervous system (CNS) have a series of unique properties, termed the blood-brain barrier (BBB), which stringently regulate the entry of molecules into the brain, thus maintaining proper brain homeostasis. We sought to understand whether neuronal activity could regulate BBB properties. Using both chemogenetics and a volitional behavior paradigm, we identified a core set of brain endothelial genes whose expression is regulated by neuronal activity. In particular, neuronal activity regulates BBB efflux transporter expression and function, which is critical for excluding many small lipophilic molecules from the brain parenchyma. Furthermore, we found that neuronal activity regulates the expression of circadian clock genes within brain endothelial cells, which in turn mediate the activity-dependent control of BBB efflux transport. These results have important clinical implications for CNS drug delivery and clearance of CNS waste products, including Aß, and for understanding how neuronal activity can modulate diurnal processes.
