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Deeksha Gambhir, Lori Fotheringham, Xing Yu, Haibo Wang, Adriana Vieira de Abreu, M Elizabeth Hartnett; Effect of CCR3 inhibition on retinal health in a murine model of laser-induced choroidal neovascularization (CNV). Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3388.
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© ARVO (1962-2015); The Authors (2016-present)
Evidence supports the C-C chemokine receptor type-3 (CCR3) signaling pathway in neovascular age-related macular degeneration (AMD), but CCR3 expression increases in aged neural retinas raising the question whether inhibition of CCR3 signaling to treat CNV might be deleterious to the neural retinal health. We tested the hypothesis that CCR3 inhibition at a dose that suppressed choroidal neovascularization (CNV) reduces retinal survival using a mouse model of laser-induced CNV.
C57Bl/6 wild-type mice at 6-8 weeks of age were treated with green photocoagulation using the Micron IV delivery system. 4-5 laser spots focused at the retinal pigment epithelium were delivered at 400 mW ,100ms to each eye. Following laser, each animal received bilateral 1 μl intravitreal injections of either the CCR3 inhibitor, SB328437 (CCR3i, Calbiochem, 10 μg/μl), or DMSO control. At days 3 and 7, the laser spots were imaged using the Micron IV Optical Coherence Tomography (OCT) module, and the length and height of CNV lesions were measured in CCR3i and control treated eyes. Eyes harvested at day 7 were processed for 1) lectin-stained choroidal flat mounts measured for CNV volume as pixels of fluorescence summed in 3 um optical sections taken through each lesion or 2) immunohistochemical staining and analysis. Cell death was determined in frozen retinal sections and counted as the number of TUNEL+ cells measured in the CNV lesion or in areas outside CNV lesions. For each group, CCR3i and control, 10 animals were analyzed for flat mounts, OCTs and sections. Student’s t-test or Mann-Whitney U test was used for statistical analysis.
Compared to control, CNV lesion length, but not height, was significantly reduced in the CCR3i group at day 7 (p<0.05) but not at day 3. In the CCR3i group, CNV volumes were approximately half the size of DMSO control (p<0.05) at day 7. Compared with control, TUNEL+ cells were increased significantly in CNV lesions in the CCR3i group (p <0.05). A non-significant increase in TUNEL+ cells was observed in retina outside the CNV lesions of CCR3i compared to control (p-value=0.08).
CCR3 inhibition increased cell death in CNV lesions in association with reduced CNV volumes. These preliminary data suggest that CCR3 inhibition may be safe for CNV treatment but further investigation is indicated.
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