Deletion of the FHL2 gene attenuating neovascularization after corneal injury.

PURPOSE: The four-and-one-half LIM domain-containing protein2 (FHL2) is a member of the four-and-a-half LIM domain-only (FHL) gene family. Although FHL2 is expressed in the cornea, its role in angiogenesis is unclear. The aim of this study was to investigate the role of the FHL2 gene in corneal angiogenesis after chemical injury.

METHODS: FHL2-LacZ knock-in mice were used to trace FHL2 gene expression before and after corneal injury. Corneal angiogenesis between FHL2-null mice and wild-type mice that underwent chemical and mechanical denudation of corneal and limbal epithelium were compared. New growth vessel density was assessed by CD31 staining and was analyzed using image analysis software. Levels of vascular endothelial growth factor (VEGF) and cyclooxygenase (COX)-2 proteins were determined by Western blot assay.

RESULTS: beta-Galactosidase staining of corneal tissue in FHL2-LacZ knock-in mice revealed that FHL2 gene expression is upregulated in the corneal epithelium after corneal injury. Ten days after injury, corneal neovascularization was observed in control and FHL2-null mice. New corneal vessel density was found to be lower in the FHL2-null mice injury group than in the wild-type mice injury group. Western blot analysis showed that VEGF and COX-2 protein levels were higher after chemical injury in FHL2-null mice and wild-type mice. However, the upregulated VEGF protein was significantly lower in the FHL2-null mice than in the wild-type mice.

CONCLUSIONS: The decreased chemical-induced corneal angiogenesis found in the FHL2-null mice in this study indicated that FHL2 protein plays a role in inhibiting inflammatory angiogenesis.