Siponimod as a novel inhibitor of retinal angiogenesis: in vitro and in
vivo evidence of therapeutic efficacy
Abstract
Background and Purpose: S1P receptors control endothelial cell
proliferation, migration, and survival. Evidence of the ability of S1P
receptor modulators to influence multiple endothelial cell functions
suggests their potential use for antiangiogenic effect. The main purpose
of our study was to investigate the potential of siponimod for the
inhibition of ocular angiogenesis in vitro and in vivo. Experimental
Approach: We investigated the effects of siponimod on the metabolic
activity (MTT assay), basal proliferation and growth factor induced
proliferation (BrdU assay), and migration (transwell migration assay) of
human umbilical vein endothelial cells (HUVEC) and retinal microvascular
endothelial cells (HRMEC). The effects of siponimod on HRMEC monolayer
integrity, and barrier function under basal conditions and TNF-α induced
disruption were assessed using the trans-endothelial electrical
resistance (TEER) and FITC-dextran permeability assays. Siponimod’s
effect on TNF-α induced claudin-5 distribution in HRMEC was investigated
using immunofluorescence. Finally, the effect of siponimod on ocular
neovascularization in vivo was assessed using suture-induced corneal
neovascularization in albino rabbits. Key Results: Siponimod did not
affect endothelial cell proliferation or metabolic activity, but
significantly inhibited endothelial cell migration, increased HRMEC
barrier integrity, and reduced TNF-α induced barrier disruption.
Siponimod also protected against TNF-α induced disruption of claudin-5
in HRMEC. These actions are mainly mediated by S1PR1 receptor
modulation. Finally, siponimod prevented the progression of
suture-induced corneal neovascularization in albino rabbits. Conclusion
and Implications: The effects of siponimod on various processes known to
be involved in angiogenesis support its therapeutic potential in
disorders associated with ocular neovascularization.