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H. Tian, Y. Zhou, J. Elison, W. C. Gordon, P. Gjorstrup, N. G. Bazan; Resolvin E1 or a Resolvin E1 Analog Inhibits Vascular Leakage in Experimental Choroidal Neovascularization (CNV). Invest. Ophthalmol. Vis. Sci. 2008;49(13):5414. doi: https://doi.org/.
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Macular degeneration involves immune inflammatory responses that, in the case of the wet form, results in CNV. Since resolvins promote resolution of inflammation leading to tissue repair, we tested RvE1 and an RvE1 analog as potential down-regulators of CNV.
Laser-induced CNV in mice consisted in 4 lesions positioned at 3, 6, 9, and 12 o’clock around the optic nerve. Laser pulses delivered by a green diode Lumenis Novus-Spectra laser mounted on a Topcon slit lamp (SL-D7), was 200 mW of energy, and 100 mS duration, and made a 50 µm diameter burn that produced a bubble as Bruch’s membrane was breached. Resolvins, RX-10001 (RvE1), RX-10008 (RvE1 analog), or vehicle (saline/ethanol) were delivered IP (50 nM stock; 18.7 and 14.3 µg/kg, respectively) on days 1, 2, 4, 6, and 8. At days 7 and 14, images of FITC leakage were obtained from lesions 5 min after IP delivery of FITC. These images were captured and viewed with the Topcon IMAGEnet 2000 LITE digital imaging system, and ranked as strong, moderate, slight, and none by an ophthalmologist. Strong linkage would be considered clinically relevant in humans. Eyes were collected 1 day later and fixed, and retinas removed, leaving a flat-mounted choroid which was labeled with FITC-conjugated Isolectin B4 (specific for endothelial cells). Diameters of choroidal lesions (laser + 15 days) were then plotted.
In controls 75% of the lesions displayed leakage at 7 days, and 56% at day 14. However, RvE1 and RX-10008 showed 7% and 26% leakage, respectively at day 7, and 4% and 6% leakage for these treatments at day 14. The number of "none" leakage was 86% for RvE1 and 72% for the analog, as compared to 15% in controls at day 14. Endothelial cell labeling indicated that choroid lesions were 14 µm and 43 µm in diameter in RvE1 and the RvE1 analog, respectively, as compared to 105 µm in controls.
Reduction in leakage the first week suggests that RvE1 protected by acting on early events, and while the RX-10008 reduced leakage, it was not as efficient by day 7. However, by 14 days, when injury-mediated changes are not involved, the effect of the analog approached that of RvE1. The lesion was reduced 70% with RvE1, but remained unchanged with the analog, while lesions of the controls increased, suggesting that RvE1 may be more efficient than the analog in reducing CNV. Thus, we suggest that RvE1 may be an early counter-regulator of signaling that promotes pathogenic angiogenesis in AMD. The further pharmacological development of RvE1 or RvE1-like analogs for therapeutic purposes in AMD is suggested.
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