Therapeutic potential of semaphorin 3E for the treatment of choroidal neovascularization.

PURPOSE We investigated the effects of semaphorin 3E (Sema3E)/PlexinD1 signaling in the development of choroidal neovascularization (CNV) and explored the therapeutic potential of the pathway. METHODS We used a laser-induced CNV model in the mouse. The expression of Sema3E and PlexinD1 was evaluated with immunohistochemistry, real-time RT-PCR, and Western blotting. After the intravitreal injection of Sema3E, the CNV size was measured on immunostained flat mounts. The CNV size was compared between inducible PlexinD1 homozygous mice and heterozygous knockout mice. RESULTS The presence of PlexinD1 was confirmed immunohistochemically in the endothelial cells of CNV. The expression of PlexinD1 mRNA was elevated after laser photocoagulation with its peak expression at day 5 (1.72 times, compared to baseline; P < 0.01). The intravitreal injection of recombinant Sema3E decreased the CNV size (16,320.9 ± 8316.0 μm(2) in the control eyes versus 9487.4 ± 4424.1 μm(2) in the eyes administered 0.1-μg Sema3E, P < 0.01). This inhibitory effect of Sema3E in the formation of CNV was canceled in the inducible PlexinD1 knockout mice (24,920.8 ± 24,684.8 μm(2) in homozygous knockout mice and 13,152.6 ± 7973.0 μm(2) in heterozygous knockout mice, P = 0.014). CONCLUSIONS These results indicate that Sema3E-PlexinD1 signaling is involved in the development of CNV. Stimulation of the pathway has therapeutic potential for CNV. Further studies are needed to evaluate the effects for clinical applications.