Investigation Of The Relationship Between IL-18 VEGF And Corneal Neovascularization

PerfaceKeratopathy is one of the common blind ophthalmopathies in our country , which constitutes second among them. Many cytokines and growth factors are in-voloved in tissue repair and control . During the keratopathy healing and repair , they promote fibroblast multiplication and angiogenesis , finally lead to corneal neovascularization ( CNV). CNV severely affects corneal transparency and becomes one of the common causes of keratopathy - induced blindness , which brings a difficult problem to the theraphy of keratitis , keratopathy rejection , corneal chemical injuries and so on . So every country s scholars think it is a focus on studying the mechanism of CNV and interfering its formation. According to many researches , vascular endothelial growth factor (VEGF) may have important effects on CNV . Recently it is found that IL -18 has an inhibitory action that have not still been reported between IL - 18 and angigenesis in the ophthalmology field on tumor angiongenesis . So in the study the expression of IL18 and VEGF are detected in normal corneas and pathological corneas (including vascular corneas and avascular corneas ) by immunohistochemistry ( IHC ) technique and the correlatin analysis are made. Investigating the mechanism of CNV would provide a theory basis for clinical theraphy.Experimental materialsTen cases of normal corneas and thirty - eighty cases of morbid corneas were collected during corneal transplantation in China medical college from Janto Oct 2003. The main reagents and equipments are rabbit polyclonal anti - human IL -18, rabbit polyclnal anti - human VEGF, SABC reagent box, computer collection and analysis system of immunohistochemistry.MethodsThe corneal specimens were conserved in profound hypothermia ice box( -80t ) after anti - freezing and rewarmed in thermostat water bath ( + 40 C ). The next step is to test the expression of IL - 18 and VEGF in group (normal corneas, vascular corneas, avascular corneas) and to analysis the correlation between them.ResultsIn normal corneas, the positive expression pf IL - 18 and VEGF were all presented in corneal epithelis, Bowman's membrane, endothelia. Spearman relationship analysis showed the IL -18 expression levels were negatively correlated with that of VEGF in every group. In vascular corneal specimens, the expression of IL - 18 decreased but that of VEGF increased and stronger expression was presented in the epithelia, stroma, the area of corneal neovascularization, inflammatory cells. The positive staining of IL - 18 in avascular corneal specimens has no statistic difference than in normal corneas, but the stronger expression of VEGF were found.DiscussionTransparent and avascular are important characters in cornea, which are related to compact instruction and inhibitory factors existence.Recently, scholars think that there are many angiogenesis factors and an-giogensis inhibition factors and the stabilization between them would keep corneal transpareat and avascular in cornea. Cornea injury would lead to the balance damage and angiogenesis factors'up -regulation. Finally CNV forms and obvi-ously decreases diminution of vision.This study showed that in normal corneas the basic expression of IL - 18 and VEGF was presented and IL - 18 might inhibit VEGF over - expression in physiological condition. So the expressional balance plays an important role in corneal self - stabilization state. In avascular morbid cornea, the IL - 18 levels decreased slightly, the up - regulated VEGF only took part in the morbid corneal repair but not caused angiogenesis. In vascular cornea, the inhibition action was thorough damaged and VEGF had rapidly high production and promoted endothe-lial cells migration , proliferation and blood vessel effusion. Expression of VEGF increasing led to CNV. From it we see that inhibition relation between IL -18 and VEGF plays an important role which modulates physiological and pathological course in complicated factor net of cornea. The further study which IL -18 inhibits CNV will p...