Purpose: An RGD modified endostatin-derived synthetic peptide, named HM-3, is a polypeptide angiogenesis inhibitor previously synthesized in our laboratory. To evaluate the effect and mechanism of HM-3 on laser-induced choroidal neovascularization (CNV) in mice.
Methods: CNV was induced in both eyes of 50 C57BL/6-background mice using laser-induced rupture of Bruch's membrane. After retinal photocoagulation, those mice were randomly divided into 5 groups. Balanced salt solution (for control), HM-3 (10 mg/ml; 20 mg/ml and 40mg/ml) and bevacizumab (25 mg/ml) was administered intravitreally immediately after laser application for each eye (1 μl). Fundus fluorescein angiography (FFA) and fluorescein isothiocyanate (FITC) dextran were performed to observe the choroid vessels and to evaluate vessel leakage by fluorescence intensity at day 7 and 14. Immunohistochemistry and Western blot were used to detect vascular endothelial growth factor (VEGF), IL-6 and extracellular regulated protein kinases (ERK1/2).
Results: FFA and FITC-dextran verified that the mean CNV area was significantly reduced in the eyes with HM-3 (40mg/ml) injection by 47.3% compared with control mice (P<0.01). The reduction of the CNV area in the HM-3 group (10mg/ml, 20mg/ml) and bevacizumab group were 33.1%，41.2% and 39.8%, respectively. Immunohistochemistry detected that VEGF, IL-6 and ERK1/2 mainly expressing in the new fibrovascular tissue. Western blot showed that VEGF and ERK1/2 was highly increased in tissue explants of retinal pigment epithelium (RPE) and choroid in control group. But for tissue explants of RPE and choroid with HM-3 and bevacizumab injection, both the expression of VEGF, IL-6 and ERK1/2 were inhibited.
Conclusions: HM-3 both inhibits newly forming CNV and regresses established CNV. Inhibiting of the inflammatory reaction and angiogenic ability via the ERK1/2 signal may be a useful therapeutic strategy for treating CNV associated with age-related macular degeneration. |
