The protective effect of Akexotide against ocular bacterial infection in rats

Background: Infectious keratitis, a medical emergency with acute and rapid disease progression may lead to severe visual impairment and even blindness. Herein, an antimicrobial polypeptide from Crassostrea gigas, which the lab named Akexotide (Is or Os), was evaluated for its therapeutic efficacy against keratitis caused by Staphylococcus aureus as well as Escherichia coli infection in rats, respectively. Methods: : Infectious keratitis models were constructed by scratching the ocular surface of rats infected with S. aureus and E.coli , respectively. The two models were treated by giving 100μL 100μM Is drops, respectively. Positive drugs for S. aureus and E. coli infection were cefazolin eye drops and tobramycin eye drops, respectively. For the curative effect, the formation of blood vessels in the fundus was observed by a slit lamp. At the end day, the condition of the injured eye was photographed by cobalt blue light using 5μL of 1% sodium fluorescein. The pathological damage of corneal tissues was done using HE staining, and the expression level of vascular endothelial growth factor (VEGF) was detected by immunohistochemistry. Results: : Akexotide Is alleviated the symptoms of corneal neovascularization as observed by slit lamp and cobalt blue lamp. The activity of S. aureus and E.coli is inhibited by Is to protect corneal epithelial cells and reduce corneal stromal bacterial invasion. It also prevented corneal thickening, as well as inhibited neovascularization by reducing VEGF expression at the cornea. Conclusion: Akexotide Is can effectively inhibit keratitis caused by E.coli as well as S. aureus in rats, as reflected by the inhibition of corneal neovascularization and the reduction of bacterial damage to the cornea.