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 2

S1p2–/– retinas display increased intraretinal vascularization and decreased intravitreal neovascularization during the course of hypoxia.

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S1p2–/– retinas display increased intraretinal vascularization and decr...
(A and E) At P12, vascular obliteration was similar in S1p2+/+ (34.2% ± 2.14%; n = 4), S1p2+/– (31.2% ± 0.9%; n = 3), and S1p2–/– whole mount retinas (31.9% ± 3.6%; n = 2, *P = 0.37) stained for GS-lectin. (B and E) At P14, vascular obliteration was also similar in S1p2+/– (34.19% ± 0.74%; n = 3) and S1p2–/– (32.49% ± 2.4%; n = 6; **P = 0.1) retinas. (C and E) At P16, S1p2+/– retinas developed abnormal buds (arrowhead), and the capillary-free area was 16.6% ± 1.9% (n = 3); S1p2–/– retinas had improved vascular morphology (arrow) and reduced capillary-free area (8.6% ± 1.7%; n = 7; ***P < 0.001). (D and E) At P17, S1p2+/+ (n = 2) and S1p2+/– (n = 11) retinas displayed 13.5% ± 1.3% and 13.15% ± 1.8% vascular obliteration, respectively, and increased neovascularization (arrowhead, inset; scale bar: 100 μm); S1p2–/– retinas (n = 9) showed significantly decreased capillary-free area (2.6% ± 2.9%; #P < 0.0001). Scale bar: 200 μm. (F and G) At P17, PAS and hematoxylin–stained cross section of S1p2+/+ retinas with evident formation of vascular tufts (VT). (H) At P15, the mean number of neovascular nuclei/section for S1p2+/+ and S1p2+/– was 22.5 ± 3.7 (n = 2) and 19.58 ± 2.43 (n = 4), respectively. S1p2–/– retinas showed a decreased number, 11.27 ± 2.16 (n = 4; *P < 0.0025). At P17, the mean number of neovascular nuclei/section for S1p2+/+ and S1p2+/– retinas was 37.6 ± 7.03 (n = 3) and 34.528 ± 6.2 (n = 5), respectively. S1p2–/– retinas displayed a reduced number, 19.62 ± 2.2 (n = 6; #P < 0.001). Scale bar: 100 μm (F) and 10 μm (G). Values represent mean ± SD. HT, heterozygous.