The Inhibitory Effect And Mechanism Of Interleukin-12 On Corneal Neovascularization

Purpose:To investigate if interleukin-12 has inhibitory effect on comeal neovascularization of alkali-burn model as well as its underlying mechanism.Methods:A total of 52 rats were included in this study.Of which,48 were established corneal neovascularization using alkali burns method.The rats were divided into four groups with different intervention as follows:1)Group 1(blank group,n=4)without treatment with alkali burns and eye drops;2)Group 2(control group,n=16)with sterilized saline eye drops;3)Group 3(experimental group,n=16)with interleukin-12 eye drops(2.5u/ml);and 4)Group 4(experimental group,n=16)with interleukin-12 eye drops(5 u/ml).Slit lamp photography was took on day 3,7,10,and 14 post-intervention and the corneal opacity as well as the length and area of corneal neovascularization were analyzed.Eyeballs of rats on the 7th and 14th day were removed for further study.Some of them were subjected to observe the changes of the corneal morphology using HE staining after paraffin embedding(four rats/group).The other rats were used to detect the mRNA and protein expression of IFN-?,CXCL10,and CXCL9 using qPCR and Western-Blot after removing cornea(twelve rats/group).Results:The corneal opacity and edema in the experimental groups were significantly improved since D5 as compared to the control group(P<0.05)but no different change was observed between the two experimental groups.The length of the corneal neovascularization in the experimental groups increased more slowly from D3(P<0.05)and the area of that were smaller on day 7 and day 14 post-intervention compared with the control group(P<0.05).Inter-comparison of the experimental groups identified the area and length of the corneal neovascularization in group 4 was smaller than that in group 3 on day 7(P<0.05)but the difference was not observed on day 14(P>0.05).In histomorphology,the number of neovascularization in the two experimental groups was less than that of the control group on day 7 and day D14.The immunohistochemistry of rat cornea showed that CXCL9,CXCL10 and IFN-y were mainly expressed in the corneal epithelium in each group and there was no significant difference between the experimental group and the control group as well as inter-experimental groups(P>0.05).qPCR and Western-Blot showed that there were significant differences in the expression of gene and protein between the experimental group and the control group under different intervention and different time points.Conclusion:IL-12 has certain inhibitory effect on corneal neovascularization.The effect at high concentration is significantly better than that at low concentration in the early stage,but it is presumed that the effect might be the same in the long term.We assume that the IL-12 may inhibit the development of corneal neovascularization by regulating the expression of IFN-y,CXCL10 and CXCL9.