Effects of Intravitreal Injection of KH902 on the Retinas of Streptozotocin-Induced Diabetic Rats

Yan Luo, Jun Huang, Xiaoyun Chen, Shiqing Li, Wei Xiao, Tao Li, Xialin Liu, Shibo Tang

State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, 510060, P.R. China

Purpose. VEGF plays a crucial role in the pathogenesis of diabetic retinopathy. KH902 is a fusion protein which combines ligand binding elements taken from the extracellular domains of vascular endothelial growth factor (VEGF) receptors 1 and 2 and the Fc portion of IgG1. This study is to investigate the effect of intravitreal injection of KH902 on the retinas of streptozotocin (STZ)-induced diabetic rats.

Methods. Diabetic rats were induced by a single intraperitoneal injection of 65 mg/kg STZ and evenly divided into 3 groups(n=15). The left eyes of diabetic rats in each group were received intravitreal injection of 3ul PBS, 15ug/3ul Avastin or 15ug/3ul KH902 respectively. The left eyes of normal rats in control group(n=15)were also received intravitreal injection of 3ul PBS. 4 weeks after intravitreal injection, the retinal function is measured by electroretinogram. The integrity of blood retinal barrier (BRB) was evaluated by Evans blue and DAPI perfusion. The expression of Flk-1, Akt, p-Akt, ERK, p-ERK, PI3K, Src and p-Src in the retina was assayed by western blot. The localization and distribution of laudin-5 and occludin were analyzed by double immunofluorescent staining of retinal whole mount.

Results. 4 weeks after intravitreal injection of KH902, the diabetic rats had significantly better retinal function, BRB function and the decreasead protein levels of Flk-1, Akt, p-Akt, p-ERK, PI3K and P-Src compared with diabetic rats treated by PBS and Avastin.. Claudin-5 and occludin in the retinas of diabetic rats treated with KH902 showed much smoother, linearer and more uniform distribution on the cell boundaries of endothelial cells of retinal vessels than those of diabetic rats treated by PBS and Avastin.

Conclusions. Intravitreal injection of KH902 could significantly improve the retinal function and inhibit the breakdown of BRB by downregulating the expression of Flk-1, Akt, p-Akt, p-ERK, PI3K and P-Src in the diabetic rats induced by STZ. The data suggest that intravitreal injection of KH902 may be a potential treatment for patients with diabetic retinopathy.