| ObjectiveCorneal allograft rejective is the most effective treatment for corneal blindness,but corneal graft reaction is the main cause of corneal allograft. Cornealneovascularization(CNV)is one of the most causes of corneal blindness and the high risk factor of corneal graft rejective reaction.Thus,how to prevent and treat corneal graft rejective reaction and corneal neovascularization is the emphasis in the research area of corneal disease.The current study shows that the balance of angiogenic factors and antiangiogenesis factors is broken during inflammation, infection, degeneration and trauma of cornea that stimulate the process of CNV.NO not only is a kind of endogenous vasodilators but an inflammation of the medium.The role of iNOS isoforms in angiogenesis is controversial. So we believe that iNOS is closely related with the occurrence and development of CNV.In addition, NO is considered to indicated immune function in a series of the vivo and vitro test. Thus, iNOS may be involved the process of corneal allograft rejection and neovascularization.MethodsPenetrating keratoplasty(PKP)was proformed orthotopically from 15 wistar rats to 30 SD rat recipients; 18 SD rats were proformed auto penetrating keratoplasty group; control group consist of 3 healthy normal SD rats (6 eyes).5 animals in PKP groups and 2 animals in auto PKP groups were killed respectively at the 1 st day,3rd day,1 st week,2nd week,3rd week and 4th week postoperatively and 3 animals in control group were killed before the end of the experiment. Observe cornea implant with slit lamp microscope everyday after operation and score three indexes,corneal opacity,edema and new vessals. CNV and inflammation were evaluated with HE staining. INOS expression was examined by immunohistochemistry. Immunohistochemistry combined with computerassisted image analysis to average gay density in corneal graft at different times. The average positive rate was enumerated in corneal wound zone(×400 micro.field).Result(1) In PKP groups,the corneal graft showed obvious edema at 1 day. The neovascuariz-ation was observed at the edge of corneal graft at 7 day,and the peak was at 14 day,and the regression from 21 day. The degree of the CNV and rejection was fiercer in experimental group at the same time.(2) The neovascularization and mass inflammatory cell was observed at the slice at 7 day,and the peak was at 14 day,and subsided after 21 days. The degree of the CNV and inflammatory cell was fiercer in experimental group at the same time.(3)The normal rat corneas expressed slightly iNOS in the basis epithelium and stroma. The expression increased notedly in auto PKP and experimental group(P =0.000,0.000,0.000,0.000,0.000,0.000,0.001,0.000,0.000,0.000,0.000, 0.000,0.000,F= 236.453,132.785,144.727,326.412,163.883,53.116,25.868,140.831,123.902,64.913,264.474,378.131). INOS can be expressed mainly in inflammation cells of stroma, corneal epithelium and the newly vessel endothelial cell. The strongest expression of iNOS is at the 14 day. The expression increased notedly in experime-ntal group at the same time(P=0.002.0.025,0.042,0.027,0.034, F=19.91,7.80,6.04.8.64,6.52).ConclusionThe expression of iNOS in corneas after PKP in rat is remarkable and iNOS take an important part in allograft rejection and CNV.
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