β-LGND2, an ERβ selective agonist, inhibits pathologic retinal neovascularization

PURPOSE The goal of our study was to evaluate the in vitro and in vivo anti-angiogenic effects of ERβ selective agonist, β-LGND2, using human retinal microvascular endothelial cell (HRMVEC) cultures and a mouse model for oxygen-induced retinopathy (OIR). METHODS The selectivity of β-LGND2 was determined using binding and transactivation assays. The effects of β-LGND2 on pathologic neovascularization were evaluated in OIR mice by histology and retinal mounts stained with isolectin B4 to quantify aberrant angiogenesis. Gene expression and protein levels were evaluated using Q-PCR, angiogenesis protein array, and Western blotting. A cell death detection ELISA kit was used to evaluate HRMVECs following hypoxic and hyperoxic conditions. In vitro angiogenesis was evaluated by growth factor-induced proliferation, tube formation, and cell migration assays. RESULTS β-LGND2-treated OIR mice had a reduced number of neovascular tufts compared to vehicle-treated animals and a significant amount of normal blood vessel maturation similar to normoxia controls. β-LGND2 inhibited in vitro hypoxia- or hyperoxia-induced cell death and the formation of endothelial tubular structures in an ERβ-specific mechanism. However, β-LGND2 did not inhibit significantly growth factor-induced HRMVEC proliferation and migration. Gene and protein studies revealed that OIR mice treated with β-LGND2 had lower levels of pro-angiogenic factors, like VEGF and HIF1α. CONCLUSIONS β-LGND2 inhibited in vitro and in vivo pathologic neovascularization in the retina in an ERβ-specific mechanism. These results show that β-LGND2, a non-steroidal ERβ selective agonist, could be a useful therapeutic for ocular diseases involving aberrant angiogenesis, like ROP, wet-AMD, and diabetic retinopathy.