A Novel Humanized Monoclonal Antibody Against the Bioactive Lipid Sphingosine-1-Phosphate Strongly Inhibits Choroidal Neovascularization (CNV) in a Murine Model

Abstract

Purpose:: Lipids have generally been considered to serve a solely structural role as components of cellular membranes. Recently it has been discovered that lipids have the potential to act as mediators of cellular signaling. These lipids are referred to as bioactive lipids. The bioactive lysolipid sphingosine-1-phosphate (S1P) has been implicated as a pro-angiogenic factor in non-ocular disease. We sought to determine if a humanized monoclonal antibody, which binds S1P with high specificity and picomolar affinity, could diminish the angiogenesis observed in the murine laser-induced model of CNV

Methods:: Five, C57BL/6 mice were subjected to laser-induced rupture of Bruch’s membrane (3 burns/eye) and 5.0 µg/eye of the humanized and optimized monoclonal antibody, Sphingozumab, was administered via intravitreal injection on days 0 and 6. Mice were sacrificed 14 days after laser rupture and choroidal flatmounts of the sclera-choroid-RPE complex were stained using R. communis agglutinin I. Digital images were then captured using a laser scanning confocal microscope. CNV volume was calculated using a z-series capture in which the sum of the lesion area throughout the z-series was multiplied by the z thickness (4µm).

Results:: Volumetric quantification of laser induced lesions revealed a 98.5% inhibition of CNV formation at day 14 compared to vehicle (p<0.001)

Conclusions:: The bioactive lysolipid S1P plays an important and previously unrecognized role in CNV formation in this animal model. Binding S1P with a humanized monoclonal antibody virtually eliminated any histologic evidence of CNV formation. Anti-S1P therapy may be a promising new method of treating ocular diseases characterized by pathologic angiogenesis.

Keywords: choroid: neovascularization • age-related macular degeneration • retina