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Yujing Bai, Xiaoxin Li; Semaphorin 3A halts the progression of pathologic choroidal neovascularization by down-regulating the SMAD2/3 pathway induced by transforming growth factor beta. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4954.
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Choroidal neovascularization (CNV) is a major cause of visual loss in retinal diseases. Although the exact mechanism for CNV is still unclear, the up-regulation of angiogenic factors, such as vascular endothelium growth factor and transforming growth factor beta (TGFβ), are considered to play major roles in the formation and development of CNV. Semaphorin3A (Sema3A), a chemorepellent guidance molecule, has been shown to be crucial for vascular development. In the present study, we aimed to investigate the effects and possible mechanisms of Sema3A on TGF-β in the progression of pathologic CNV.
ELISA kit was used to verify the vitreous TGFβ level in neovascular AMD patients. Human umbilical vein endothelial cells (HUVECs) were used for the in vitro study, and an laser-induced CNV mouse model was used for the in vivo study. HUVECs were incubated with Sema3A, and cell proliferation, migration, apoptosis, tube formation, and SMAD2/3 signalling pathways studies were measured with Cell Counting Kit-8, Transwell, flow cytometry, Matrigel assays, and western blot. Laser-induced CNV mouse model were injected with Sema3A intravitreously immediately after CNV induction. 14 days after laser surgery, fundus fluorescein angiography were evaluated by Micron IV. In the in vivo study, western blot for SMAD2/3 signaling pathway were also evaluated.
In this study, we first verified that the vitreous TGFβ level in neovascular AMD patients was higher than the control group, and we showed that Sema3A inhibited TGFβ-induced human umbilical vein endothelial cell (HUVEC) proliferation, migration and tube formation. Sema3A also induced TGFβ-stimulated HUVEC apoptosis. In addition, Sema3A inhibited the utilization of TGFβ in vitro. In vivo, TGFβ was increased in the CNV mice model, and an intravitreal injection of TGFβ increased the leakage area for CNV. Sema3A not only inhibited laser-induced CNV formation but also inhibited TGFβ-induced CNV. In the in vitro and in vivo studies, Sema3A inhibited the downstream SMAD2/3 signaling pathway.
These results suggest that Sema3A could be a useful, adjunctive therapeutic strategy for preventing CNV formation and progression.
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