Abstract
Purpose::
Corneal neovascularization is a vision-threatening condition caused by various ocular pathological conditions. Eph receptors and ephrin ligands are involved in nerve and vessel guidance during development, vascular cell assembly, and angiogenesis. The aim of this study is to evaluate the function of the ephrin ligands and Eph receptors in vitro and in vivo in corneal angiogenesis in a mouse model.
Methods::
The pellet containing bFGF was inserted into wild type mouse. The cornea was excised and immunostained. To evaluate the function of ephrinB1, recombinant ephrinB1-Fc was used in corneal pocket assay and aortic ring assay. Calf pulmonary artery endothelial cells (CPAE) were lysed after stimulation of either ephrinB1-Fc, bFGF or combination of both, then western blot was done to quantify the downstream signaling level of bFGF (JNK, ERK and p38).
Results::
Immunohistochemical studies demonstrated that ephrinB1 and EphB1 were expressed in bFGF-induced vascularized corneas. EphB1 was specifically co-localized with vascular endothelial marker CD31 surrounded by type IV collagen. The ephrinB1 was expressed in corneal resident keratocyte and neutrophil. Recombinant ephrinB1-Fc, which induces EphB receptor activation, enhanced bFGF-induced tube formation in an in vitro aortic ring assay and promoted bFGF-induced corneal angiogenesis in vivo in a corneal pocket assay. Synergistically enhanced and sustained activation of ERK has noted in CPAE cell lines after stimulation of ephrin B1 and bFGF combinations.
Conclusions::
These results suggest that ephrinB1/EphB1 signaling plays a synergistic role in corneal neovascularization. Understanding the mechanism of Eph/ephrin signaling and regulation in angiogenesis may provide a therapeutic intervention for the treatment of not only corneal neovascularization but also angiogenesis-related disorders.
Keywords: cornea: basic science • cornea: stroma and keratocytes • vascular cells