Essential role of sphingosine 1–phosphate receptor 2 in pathological angiogenesis of the mouse retina
Athanasia Skoura, … , Richard L. Proia, Timothy Hla
Athanasia Skoura, … , Richard L. Proia, Timothy Hla
Published September 4, 2007
Citation Information: J Clin Invest. 2007;117(9):2506-2516. https://doi.org/10.1172/JCI31123.
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Research Article Ophthalmology

Essential role of sphingosine 1–phosphate receptor 2 in pathological angiogenesis of the mouse retina

Abstract

Sphingosine 1–phosphate (S1P), a multifunctional lipid mediator that signals via the S1P family of G protein–coupled receptors (S1PR), regulates vascular maturation, permeability, and angiogenesis. In this study, we explored the role of S1P 2 receptor (S1P2R) in normal vascularization and hypoxia-triggered pathological angiogenesis of the mouse retina. S1P2R is strongly induced in ECs during hypoxic stress. When neonatal mice were subjected to ischemia-driven retinopathy, pathologic neovascularization in the vitreous chamber was suppressed in S1p2–/– mice concomitant with reduction in endothelial gaps and inflammatory cell infiltration. In addition, EC patterning and normal revascularization into the avascular zones of the retina were augmented. Reduced expression of the proinflammatory enzyme cyclooxygenase-2 (COX-2) and increased expression of eNOS were observed in the S1p2–/– mouse retina. S1P2R activation in ECs induced COX-2 expression and suppressed the expression of eNOS. These data identify the S1P2R-driven inflammatory process as an important molecular event in pathological retinal angiogenesis. We propose that antagonism of the S1P2R may be a novel therapeutic approach for the prevention and/or treatment of pathologic ocular neovascularization.

Authors

Athanasia Skoura, Teresa Sanchez, Kevin Claffey, Suzanne M. Mandala, Richard L. Proia, Timothy Hla

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Figure 6

S1P2R regulates in vivo COX-2 expression during hypoxia.

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S1P2R regulates in vivo COX-2 expression during hypoxia. ...
(A) Relative VEGF, Ang-2, Flt1, TNF-α, iNOS, and COX-2 mRNA expression in HT and KO ischemic retinas at P13 (24 hours of hypoxia) as determined by quantitative RT-PCR (n = 3; *P < 0.04). Gene expression was normalized to cyclophilin A expression and expressed as fold induction over the control HT animals. (B) Fold induction of relative COX-2 mRNA expression during the course of hypoxia (n = 3; †P < 0.02). (C) Immunohistochemistry for COX-2 in retina cross sections of WT retinas showed strong expression in the nerve cells and vessels of the INL and GCL. (D) KO retinas displayed lower COX-2 expression in the vessels of the INL (arrowheads) and GCL (arrows). Counterstaining with hematoxylin. Scale bar: 10 μm. (E) Immunoblotting for COX-2, S1P2-V5, and actin expression in HUVECs transduced with AdS1P2-V5 and AdGFP. (F) Induction of promoter activity of the human COX-2 gene. phPES2(–1432/+59) luciferase reporter (0.3 μg) was cotransfected in EOMA cells with pcDNA 3.1 (control, 0.3 μg), pcDNA3.1-S1p2 receptor plasmid (0.3 μg), or pcDNA3.1-S1p1 receptor plasmid (0.3 μg). Cells transfected with phPES2(–1432/+59) luciferase reporter were treated with PMA (positive control, 100 nM). Results from 1 representative experiment are shown (‡P < 0.01, ΧP = 0.43; n = 4).