Cyclopamine inhibits corneal neovascularization and fibrosis by alleviating inflammatory macrophage recruitment and endothelial cell activation

Purpose: To explore the function of cyclopamine in corneal neovascularization and subsequent fibrosis after cornea alkali-burn injury.

Methods: In vivo, mice cornea were injured by NaOH, and then treated with cyclopamine, clodronate liposomes (CLO-LPS), and vehicle of cyclopamine separately by subconjunctival injections. Clinical features were observed and pathological characteristics were examined. In vitro, M1 macrophages (M1φ) and human umbilical vein endothelial cells (HUVECs) were co-cultured, and the abilities of proliferation, migration, and tube formation of HUVECs were detected under different interventions of M1φ.

Results: Alkali-burn injury induced massive angiogenesis and decreased transparency of the cornea, along with numerous macrophages infiltration and Shh protein expression in the cornea. However, corneal neovascularization, macrophage infiltration, and Shh expression could suppressed by cyclopamine and CLO-LPS significantly. In addition, treatment with cyclopamine also reduced the expression of inflammatory factors (TNF-α, IL-6) and fibrosis factors (VIM, α-SMA). In vitro, M1φ promotes migration and tube formation of HUVECs by secreting Shh protein, which could be inhibited by cyclopamine.

Conclusion: Cyclopamine could suppress inflammation and angiogenesis of alkali-burned cornea, as well as subsequent fibrosis. The study reveals that cyclopamine suppresses corneal neovascularization in a dual mechanism of inhibiting macrophage infiltration and suppressing Shh signaling.

Corneal neovascularization; Cyclopamine; Fibrosis; Macrophage; Sonic hedgehog.