Daphnetin Inhibits Corneal Inflammation and Neovascularization on Mouse Model of Corneal Alkali Burn

Abstract

Alkali burns are major contributors to corneal injury. Alkali burn-induced corneal inflammation often causes vision loss due to corneal neovascularization. Daphnetin (DAP) has been studied for the anti-inflammatory and anti-angiogenic properties with encouraging results. Driven by those encouraging results, we sought to explore that the effects of DAP in the treatment of alkali burn-induced corneal inflammation and neovascularization and its mechanism of action. We found that the proliferation, migration, and tube formation effects of VEGF-A were largely attenuated by treatment of HUVECs with DAP. Treatment of DAP significantly suppressed the VEGF-A-induced protein expression of VEGF receptor2 (VEGFR2), as well as the activation of downstream STAT3, AKT and ERK signaling. In the mice cornea alkali burn model, the inflammatory cell infiltrations and neovascularization caused by alkali burn were inhibited by 10 µM DAP eye drops in the cornea. Furthermore, alkali burn-induced corneal expression of VEGF-A, VEGFR2, phosphorylated (p-)STAT3, p-AKT and p-ERK in corneal tissue were largely reduced by DAP. Moreover, the upregulation of inflammatory caused by alkali burn in the pathological process was greatly neutralized by DAP. Mechanistically, the inflammatory response could be alleviated by DAP in the way of inhibiting the expression levels of TLR4, p-NF-κB, NLRP3, ASC, Cleaved-caspase-1 (p20), mature-IL-1β (p17) and N-GSDM. In conclusion, our findings confirmed that the corneal neovascularization and inflammation caused by alkali burn can be inhibited by DAP in vitro and in vivo, elucidating the underlying mechanisms of its protective effects. DAP may have great therapeutic potential for treatment of corneal alkali burn.