Article

Therapeutic interference with EphrinB2 signalling inhibits oxygen-induced angioproliferative retinopathy

University Eye Hospital, Freiburg, Germany.
Acta ophthalmologica (Impact Factor: 2.51). 09/2009; 89(1):82-90. DOI: 10.1111/j.1755-3768.2009.01609.x
Source: PubMed

ABSTRACT To investigate whether EphrinB2 (EfnB2) or EphB4 influence retinal angiogenesis under physiological or pathological conditions.
Using the mouse model of oxygen-induced proliferative retinopathy (OIR), the expression of EfnB2, EphB4, vascular endothelial growth factor (VEGF), VEGFR1 and VEGFR2 was quantified by quantitative polymerase chain reaction (qPCR) and localized in EfnB2- and EphB4-lacZ mice. Angioproliferative retinopathy was manipulated by intravitreal injection of dimeric EfnB2 and monomeric or dimeric EphB4.
Dimeric EphB4 (EphB4-Fc) and EfnB2 (EfnB2-Fc) enhanced hypoxia-induced angioproliferative retinopathy but not physiological angiogenesis. Monomeric EphB4 (sEphB4) reduced angiogenesis. The messenger RNA (mRNA) level of EfnB2 increased significantly in the hyperoxic phase (P7-P12), while EphB4, VEGF, VEGFR1 and VEGFR2 showed a significant - up to fivefold - increased expression at P14, the start of morphologically visible vasoproliferation caused by relative hypoxia.
The ephrin/Eph system is involved in angioproliferative retinopathy. Stimulation of EphB4 and EfnB2 signalling using EfnB2-Fc and EphB4-Fc, respectively, enhanced hypoxia-induced angiogenesis. In contrast, sEphB4 inhibited hypoxia-induced angiogenesis. Therefore, angiogenesis is enhanced by signalling through both EphB4 (forward) and EfnB2 (reverse). The distinction in the expression kinetics of EphB4 and EfnB2 indicates that they govern two different signalling pathways and are regulated in diverse ways. sEphB4 might be a useful drug for antiangiogenic therapy.

Download full-text

Full-text

Available from: Hellmut Augustin, Jan 10, 2015
1 Follower
 · 
137 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: EphrinB2 ligands and EphB4 receptors are expressed on endothelial cells (EC) of arteries and veins, respectively, and are essential for vascular development. To understand how these molecules regulate retinal neovascularization (NV), we evaluated their expression in a model of oxygen-induced retinopathy (OIR). EphrinB2 and EphB4 were expressed on arterial and venous trunks, respectively, and on a subset of deep capillary vessels. EphB4 expression was reduced following hyperoxia, while ephrinB2 expression remained unaltered. In addition, a subset of EphB4-positive veins regressed in a caspase-3-dependent manner during hyperoxia. Arteriovenous malformations were also observed with loss of arterial-venous boundaries. Finally, both ephrinB2 and EphB4 were expressed on a subset of neovascular tufts following hyperoxia. These data confirm the contribution of ECs from both venous and arterial origins to the development of retinal NV.
    Developmental Dynamics 06/2010; 239(6):1695-707. DOI:10.1002/dvdy.22306 · 2.67 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To characterise the ocular safety profile of sEphB4 and its pharmacokinetics in rabbit eyes. 15 rabbits with single intravitreal injection of sEphB4 in the right eye (1000 μg, 465 μg, 160 μg or 80 μg) and phosphate-buffered saline in the left eye were studied at different time points by monitoring inflammatory changes, intraocular pressure, electroretinogram and histological changes. The dose of 80 μg/eye was injected intravitreally into 21 rabbits, and the fellow eyes were used as controls for sEphB4 ocular pharmacokinetics. sEphB4 concentrations were measured in the vitreous, retina, choroids and plasma using ELISA at the designated time points. The study showed that there was no evidence of intraocular toxicity at any time point with any dose tested. No statistically significant differences were seen in the intraocular pressure, scotopic and photopic ERGs, and histopathology between the control and sEphB4 injected eyes. A pharmacokinetic study demonstrated a vitreous half-life of 4.1 days and 6.3 days in the retina. The mean residence time of the drug was 10.45 days in the retina and 7.95 days in the choroid. It seems that sEphB4 at the concentrations studied did not appear to be toxic to rabbit eyes and may be a longer-acting treatment option to the current therapies for ocular abnormal neovascularisation.
    The British journal of ophthalmology 10/2010; 94(12):1668-73. DOI:10.1136/bjo.2010.182881 · 2.81 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Eph receptor tyrosine kinases and ephrin ligands control many physiological and pathological processes, and molecules interfering with their interaction are useful probes to elucidate their complex biological functions. Moreover, targeting Eph receptors might enable new strategies to inhibit cancer progression and pathological angiogenesis as well as promote nerve regeneration. Because our previous work suggested the importance of the salicylic acid group in antagonistic small molecules targeting Eph receptors, we screened a series of salicylic acid derivatives to identify novel Eph receptor antagonists. This identified a disalicylic acid-furanyl derivative that inhibits ephrin-A5 binding to EphA4 with an IC(50) of 3 μm in ELISAs. This compound, which appears to bind to the ephrin-binding pocket of EphA4, also targets several other Eph receptors. Furthermore, it inhibits EphA2 and EphA4 tyrosine phosphorylation in cells stimulated with ephrin while not affecting phosphorylation of EphB2, which is not a target receptor. In endothelial cells, the disalicylic acid-furanyl derivative inhibits EphA2 phosphorylation in response to TNFα and capillary-like tube formation on Matrigel, two effects that depend on EphA2 interaction with endogenous ephrin-A1. These findings suggest that salicylic acid derivatives could be used as starting points to design new small molecule antagonists of Eph receptors.
    Chemical Biology &amp Drug Design 07/2011; 78(4):667-78. DOI:10.1111/j.1747-0285.2011.01199.x · 2.51 Impact Factor