Purpose: To investigate the effect of an intravitreally administered CCR2 antagonist, INCB3344, on a mouse model of choroidal neovascularization (CNV).
Methods: CNV was induced by laser photocoagulation on Day 0 in wild type mice. INCB3344 or vehicle was administered intravitreally immediately after laser application. On Day 14, CNV areas were measured on retinal pigment epithelium (RPE)-choroid flat mounts and histopathologic examination was performed on 7 µm-thick sections. Macrophage infiltration was evaluated by immunohistochemistry on RPE-choroid flat mounts and quantified by flow cytometry on Day 3. Expression of vascular endothelial growth factor (VEGF) protein in RPE-choroid tissue was examined by immunohistochemistry and ELISA, VEGF mRNA in sorted macrophages in RPE-choroid tissue was examine by real-time PCR and expression of phosphorylated extracellular signal-regulated kinase (p-ERK 1/2) in RPE-choroid tissue was measured by Western blot analysis on Day 3. We also evaluated the efficacy of intravitreal INCB3344 to spontaneous CNV detected in Cu, Zn-superoxide dismutase (SOD1) deficient mice. Changes in CNV size were assessed between pre- and 1week post-INCB3344 or vehicle administration in fundus photography and fluorescence angiography (FA).
Results: The mean CNV area in INCB3344-treated mice decreased by 42.4% compared with the vehicle-treated control mice (p<0.001). INCB3344 treatment significantly inhibited macrophage infiltration into the laser-irradiated area (p<0.001), and suppressed the expression of VEGF protein (p = 0.012), VEGF mRNA in infiltrating macrophages (p<0.001) and the phosphorylation of ERK1/2 (p<0.001). The area of spontaneous CNV in Sod1⁻/⁻ mice regressed by 70.35% in INCB3344-treated animals while no change was detected in vehicle-treated control mice (p<0.001).
Conclusions: INCB3344 both inhibits newly forming CNV and regresses established CNV. Controlling inflammation by suppressing macrophage infiltration and angiogenic ability via the CCR-2/MCP-1 signal may be a useful therapeutic strategy for treating CNV associated with age-related macular degeneration.