Purpose: To determine ephrinB1, ephrinB2 and EphB1 expression in the optic nerve head (ONH) and retina of glaucomatous monkeys and in human ONH astrocytes.
Methods: Using immunohistochemistry, the localization of ephrinB1, ephrinB2 and EphB1 was determined in the ONH and retina bilaterally of monkeys with monocular laser-induced glaucoma. RT-PCR, Western Blot and immunocytochemistry were used to study ephrinB1, ephrinB2 and EphB1 expression in cultured human ONH astrocytes from glaucomatous and normal donors.
Results: There was an increase in ephrinB1 and EphB1 expression in mild to moderate glaucoma. In the ONH, both ephrinB1 and EphB1 were localized to astrocytes, and EphB1 also localized to lamina cribrosa cells and perivascular cells. In the retina, ephrinB1 localized to Muller cells and astrocytes, and EphB1 was found in retinal ganglion cells. In glaucomatous human ONH astrocytes, ephrinB1 and EphB1 were up-regulated, but barely present in normal donors.
Conclusions: Ephrins are activated in early and moderate glaucoma in the ONH and retina. We postulate that up-regulation of Eph/ephrin pathway may play a protective role by limiting axonal damage and inflammatory cell invasion. Loss of ephrin signaling in advanced glaucoma may explain macrophage activation.
- Retinal Muller cell
- optic nerve head