Choroidal Neovascularization Is Inhibited in Splenic-Denervated or Splenectomized Mice with a Concomitant Decrease in Intraocular Macrophage

PURPOSE: To determine the involvement of sympathetic activity in choroidal neovascularization (CNV) using laser-induced CNV in a mouse model. METHODS: We investigated changes in the proportions of intraocular lymphocytes, granulocytes, and three macrophage subtypes (Ly6C(hi), Ly6C(int), and Ly6C(lo)) after laser injury in mice using flow cytometry, and evaluated CNV lesion size in mice lacking inflammatory cells. Further, we evaluated the lesion size in mice administered the β3 receptor antagonist, splenic-denervated and splenectomized mice. We also assessed changes in the proportions of intraocular macrophages and peripheral blood monocytes in splenic-denervated and splenectomized mice. Lastly, lesion size was compared between splenic-denervated mice with or without adoptive transfer of macrophages following laser injury. After Ly5.1 mice spleen-derived Ly6C(hi) cells were transferred into Ly5.2 mice, the proportions of intraocular Ly5.1(+)Ly6C(hi) cells were compared. RESULTS: In WT mice, the proportion of CD4(+) T cells recruited into the eye increased progressively from day 3 to day 7 after laser injury, whereas, intraocular CD8(+) T cells did not change significantly. Proportions of B220(+) cells, granulocytes, and two subtypes of intraocular macrophages (Ly6C(hi) and Ly6C(lo)) peaked at day 3 following laser injury. In contrast, Ly6C(int/lo)CD64(+) subtype showed a significantly higher percentage at day 7 after laser injury. There were no differences in lesion size between CD4(–/–)or Rag2(–/–)mice and controls, whereas lesion size was significantly reduced in CCR2(−/−) mice and clodronate liposome-treated mice. CNV lesion area was significantly reduced in mice with β3 blocker treatment, splenic-denervated and splenectomized mice compared with controls. Intraocular Ly6C(hi) macrophages were also reduced by splenic denervation or splenectomy. Adoptive transfer of spleen-derived Ly6C(hi) cells increased the lesion size in splenic-denervated mice. Compared with controls, intraocular donor-derived Ly6C(hi) cells recruited into the eye were reduced in splenic-denervated and splenectomized mice. CONCLUSIONS: Although lymphocytes had little effect on CNV formation, Ly6C(hi) macrophages/monocytes exacerbated CNV in mice. Sympathetic activity might contribute to CNV via the recruitment of macrophages to the eye.