Inhibition of PDGF-BB reduces alkali-induced corneal neovascularization in mice.

ABSTRACT

The aim of the present study was to investigate the role of platelet­derived growth factor (PDGF)­BB/PDGF receptor (R)­ß signaling in an experimental murine corneal neovascularization (CrNV) model. Experimental CrNV was induced by alkali injury. The intra­corneal expression of PDGF­BB was examined using immunohistochemistry. The effect of PDGF­BB on CrNV was evaluated using immunofluorescence staining. The expression levels of PDGFR­ß in human retinal endothelial cells (HRECs) under normal conditions or following cobalt chloride treatment, which induced hypoxic conditions, was assessed using reverse transcription­quantitative PCR. The effect of exogenous treatment of PDGF­BB on the proliferation, migration and tube formation of HRECs under normoxic or hypoxic conditions was evaluated in vitro using Cell Counting Kit­8, wound healing and 3D Matrigel capillary tube formation assays, respectively. The results indicated that the intra­corneal expression levels of the proteins of PDGF­BB and PDGFR­ß were detectable on days 2 and 7 following alkali injury. The treatment with neutralizing anti­PDGF­BB antibody resulted in significant inhibition of CrNV. The intra­corneal expression levels of vascular endothelial growth factor A, matrix metallopeptidase (MMP)­2 and MMP­9 proteins were downregulated, while the expression levels of thrombospondin (TSP)­1, TSP­2, a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)­1 and ADAMTS­2 were upregulated significantly in mice treated with anti­PDGF­BB antibody. The expression levels of PDGFR­ß were upregulated in HRECs under hypoxic conditions compared with those noted under normoxic conditions. Recombinant human PDGF­BB promoted the proliferation, migration and tube formation of HRECs under hypoxic conditions. The data indicated that PDGF­BB/PDGFR­ß signaling was involved in CrNV and that it promoted endothelial cell proliferation, migration and tube formation. The pro­angiogenic effects of this pathway may be mediated via the induction of pro­angiogenic cytokine secretion and the suppression of anti­angiogenic cytokine secretion.