Xanthatin inhibits corneal neovascularization by inhibiting the VEGFR2-mediated STAT3/PI3K/Akt signaling pathway

Alkali burn is one of the main causes of corneal injury. The inflammation and neovascularization caused by alkali burns aggravate corneal damage, resulting in loss of vision. The aim of the present study was to evaluate the efficacy of xanthatin in the treatment of alkali burn-induced inflammation and neovascularization. A CCK-8 assay was used to detect the effects of different concentrations of xanthatin on the proliferation of human umbilical vein endothelial cells (HUVECs). The effects of xanthatin on the migration of HUVECs and the ability of lumen formation were examined using a scratch test and lumen formation assay, respectively. A total of 60 Sprague-Dawley rats were randomly divided into two groups to establish a corneal alkali burn model, and were treated with PBS and xanthatin eye drops four times a day. A slit lamp microscope recorded changes of the cornea at 0, 4, 7, 10 and 14 days, and the inflammatory indices of the cornea and the neovascular area were evaluated. The expression levels of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF) in the cornea under different treatment conditions were detected using immunofluorescence and western blot analysis. In order to investigate the mechanism of xanthatin on the inhibition of inflammation and neovascularization, HUVECs were treated with xanthatin and PBS following VEGF treatment. The subcellular localization of signal transducer and activator of transcription 3 (STAT3) was detected using immunofluorescence. The expression levels of VEGF receptor 2 (VEGFR2), STAT3, phosphoinositide 3-kinase (PI3K) and Akt were detected using western blot analysis. The results revealed that xanthatin inhibited the proliferation of HUVECs in a concentration-dependent manner. The migration ability and lumen-forming ability of the HUVECs were also inhibited by xanthatin. Slit lamp microscopy showed that the inflammatory index and the area of neovascularization in the xanthatin-treated group were significantly reduced, compared with those in the PBS treatment group. The xanthatin treatment group exhibited a lower protein expression level of VEGF and increased protein expression level of PEDF, compared with the PBS treatment group. In the VEGF-treated HUVECs, xanthatin significantly decreased the expression levels of p-VEGFR2, phosphorylated (p-)STAT3, p-PI3K and p-Akt. In conclusion, the present study confirmed that xanthatin inhibited corneal neovascularization and inflammation in the alkali burn model, elucidating the underlying mechanisms involved in its protective effects. Therefore, xanthatin may be a novel drug for the treatment of corneal alkali burn.